Sample records for vibration control technology

  1. Performance of active vibration control technology: the ACTEX flight experiments (United States)

    Nye, T. W.; Manning, R. A.; Qassim, K.


    This paper discusses the development and results of two intelligent structures space-flight experiments, each of which could affect architecture designs of future spacecraft. The first, the advanced controls technology experiment I (ACTEX I), is a variable stiffness tripod structure riding as a secondary payload on a classified spacecraft. It has been operating well past its expected life since becoming operational in 1996. Over 60 on-orbit experiments have been run on the ACTEX I flight experiment. These experiments form the basis for in-space controller design problems and for concluding lifetime/reliability data on the active control components. Transfer functions taken during the life of ACTEX I have shown consistent predictability and stability in structural behavior, including consistency with those measurements taken on the ground prior to a three year storage period and the launch event. ACTEX I can change its modal characteristics by employing its dynamic change mechanism that varies preloads in portions of its structure. Active control experiments have demonstrated maximum vibration reductions of 29 dB and 16 dB in the first two variable modes of the system, while operating over a remarkable on-orbit temperature range of -80 °C to 129 °C. The second experiment, ACTEX II, was successfully designed, ground-tested, and integrated on an experimental Department of Defense satellite prior to its loss during a launch vehicle failure in 1995. ACTEX II also had variable modal behavior by virtue of a two-axis gimbal and added challenges of structural flexibility by being a large deployable appendage. Although the loss of ACTEX II did not provide space environment experience, ground testing resulted in space qualifying the hardware and demonstrated 21 dB, 14 dB, and 8 dB reductions in amplitude of the first three primary structural modes. ACTEX II could use either active and/or passive techniques to affect vibration suppression. Both experiments trailblazed

  2. Some problems of control of dynamical conditions of technological vibrating machines (United States)

    Kuznetsov, N. K.; Lapshin, V. L.; Eliseev, A. V.


    The possibility of control of dynamical condition of the shakers that are designed for vibration treatment of parts interacting with granular media is discussed. The aim of this article is to develop the methodological basis of technology of creation of mathematical models of shake tables and the development of principles of formation of vibrational fields, estimation of their parameters and control of the structure vibration fields. Approaches to build mathematical models that take into account unilateral constraints, the relationships between elements, with the vibrating surface are developed. Methods intended to construct mathematical model of linear mechanical oscillation systems are used. Small oscillations about the position of static equilibrium are performed. The original method of correction of vibration fields by introduction of the oscillating system additional ties to the structure are proposed. Additional ties are implemented in the form of a mass-inertial device for changing the inertial parameters of the working body of the vibration table by moving the mass-inertial elements. The concept of monitoring the dynamic state of the vibration table based on the original measuring devices is proposed. Estimation for possible changes in dynamic properties is produced. The article is of interest for specialists in the field of creation of vibration technology machines and equipment.

  3. Model Indepedent Vibration Control


    Yuan, Jing


    A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is

  4. A Review of the Evaluation, Control, and Application Technologies for Drill String Vibrations and Shocks in Oil and Gas Well

    Directory of Open Access Journals (Sweden)

    Guangjian Dong


    Full Text Available Drill string vibrations and shocks (V&S can limit the optimization of drilling performance, which is a key problem for trajectory optimizing, wellbore design, increasing drill tools life, rate of penetration, and intelligent drilling. The directional wells and other special trajectory drilling technologies are often used in deep water, deep well, hard rock, and brittle shale formations. In drilling these complex wells, the cost caused by V&S increases. According to past theories, indoor experiments, and field studies, the relations among ten kinds of V&S, which contain basic forms, response frequency, and amplitude, are summarized and discussed. Two evaluation methods are compared systematically, such as theoretical and measurement methods. Typical vibration measurement tools are investigated and discussed. The control technologies for drill string V&S are divided into passive control, active control, and semiactive control. Key methods for and critical equipment of three control types are compared. Based on the past development, a controlling program of drill string V&S is devised. Application technologies of the drill string V&S are discussed, such as improving the rate of penetration, controlling borehole trajectory, finding source of seismic while drilling, and reducing the friction of drill string. Related discussions and recommendations for evaluating, controlling, and applying the drill string V&S are made.


    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern


    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.


    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern


    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed. The month of June, 2004 was primarily occupied with the writing of the Phase I Final Report, the sole deliverable of Phase I, which will be submitted in the next quarter. Redesign of the laboratory prototype and design of the downhole (Phase II) prototype was

  7. Active vibration control of civil structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, C.; Baker, W.; Fales, J.; Shevitz, D.


    This is a final report of a one year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Active vibration control (AVC) of structural and mechanical systems is one of the rapidly advancing areas of engineering research. The multifaceted nature of AVC covers many disciplines, such as sensors and instrumentation, numerical modeling, experimental mechanics, and advanced power systems. This work encompassed a review of the literature on active control of structures focusing both on active control hardware and on control algorithms, a design of an isolation systems using magneto-rheological fluid-filled (MRF) dampers and numerical simulations to study the enhanced vibration mitigation effects of this technology.

  8. Resonant vibration control of rotating beams

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker


    Rotatingstructures,like e.g.wind turbine blades, may be prone to vibrations associated with particular modes of vibration. It is demonstrated, how this type of vibrations can be reduced by using a collocated sensor–actuator system, governed by a resonant controller. The theory is here demonstrated...... modal connectivity, only very limited modal spill-over is generated. The controller acts by resonance and therefore has only a moderate energy consumption, and successfully reduces modal vibrations at the resonance frequency....


    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern


    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the testing of the rebuilt laboratory prototype and its conversion into a version that will be operable in the drilling tests at TerraTek Laboratories. In addition, formations for use in these tests were designed and constructed, and a test protocol was developed. The change in scope and no-cost extension of Phase II to January, 2006, described in our last report, were approved. The tests are scheduled to be run during the week of January 23, and should be completed before the end of the month.

  10. Actively controlled vibration welding system and method (United States)

    Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An


    A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

  11. Vibration Isolation Technology (VIT) ATD Project (United States)

    Lubomski, Joseph F.; Grodsinsky, Carlos M.; Logsdon, Kirk A.; Rohn, Douglas A.; Ramachandran, N.


    A fundamental advantage for performing material processing and fluid physics experiments in an orbital environment is the reduction in gravity driven phenomena. However, experience with manned spacecraft such as the Space Transportation System (STS) has demonstrated a dynamic acceleration environment far from being characterized as a 'microgravity' platform. Vibrations and transient disturbances from crew motions, thruster firings, rotating machinery etc. can have detrimental effects on many proposed microgravity science experiments. These same disturbances are also to be expected on the future space station. The Microgravity Science and Applications Division (MSAD) of the Office of Life and Microgravity Sciences and Applications (OLMSA), NASA Headquarters recognized the need for addressing this fundamental issue. As a result an Advanced Technology Development (ATD) project was initiated in the area of Vibration Isolation Technology (VIT) to develop methodologies for meeting future microgravity science needs. The objective of the Vibration Isolation Technology ATD project was to provide technology for the isolation of microgravity science experiments by developing methods to maintain a predictable, well defined, well characterized, and reproducible low-gravity environment, consistent with the needs of the microgravity science community. Included implicitly in this objective was the goal of advising the science community and hardware developers of the fundamental need to address the importance of maintaining, and how to maintain, a microgravity environment. This document will summarize the accomplishments of the VIT ATD which is now completed. There were three specific thrusts involved in the ATD effort. An analytical effort was performed at the Marshall Space Flight Center to define the sensitivity of selected experiments to residual and dynamic accelerations. This effort was redirected about half way through the ATD focusing specifically on the sensitivity of


    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern


    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. As a result of the lower than expected performance of the MR damper noted last quarter, several additional tests were conducted. These dealt with possible causes of the lack of dynamic range observed in the testing: additional damping from the oil in the Belleville springs; changes in properties of the MR fluid; and, residual magnetization of the valve components. Of these, only the last was found to be significant. By using a laboratory demagnetization apparatus between runs, a dynamic range of 10:1 was achieved for the damper, more than adequate to produce the needed improvements in drilling. Additional modeling was also performed to identify a method of increasing the magnetic field in the damper. As a result of the above, several changes were made in the design. Additional circuitry was added to demagnetize the valve as the field is lowered. The valve was located to above the Belleville springs to reduce the load placed upon it and offer a greater range of materials for its construction. In addition, to further increase the field strength, the coils were relocated from the mandrel to the outer housing. At the end of the quarter, the redesign was complete and new parts were on order. The project is approximately three months behind schedule at this time.

  13. Simulation studies for multichannel active vibration control (United States)

    Prakash, Shashikala; Balasubramaniam, R.; Praseetha, K. K.


    Traditional approach to vibration control uses passive techniques, which are relatively large, costly and ineffective at low frequencies. Active Vibration Control (AVC) is used to overcome these problems & in AVC additional sources (secondary) are used to cancel vibration from primary source based on the principle of superposition theorem Since the characteristics of the vibration source and environment are time varying, the AVC system must be adaptive. Adaptive systems have the ability to track time varying disturbances and provide optimal control over a much broader range of conditions than conventional fixed control systems. In multi channel AVC vibration fields in large dimensions are controlled & is more complicated. Therefore to actively control low frequency vibrations on large structures, multi channel AVC requires a control system that uses multiple secondary sources to control the vibration field simultaneously at multiple error sensor locations. The error criterion that can be directly measured is the sum of squares of outputs of number of sensors. The adaptive algorithm is designed to minimize this & the algorithm implemented is the "Multiple error LMS algorithm." The best known applications of multiple channel FXLMS algorithm is in real time AVC and system identification. More wider applications are in the control of propeller induced noise in flight cabin interiors. In the present paper the results of simulation studies carried out in MATLAB as well as on TMS320C32 DSP processor will be brought out for a two-channel case.

  14. Model Predictive Vibration Control Efficient Constrained MPC Vibration Control for Lightly Damped Mechanical Structures

    CERN Document Server

    Takács, Gergely


    Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: ·         the implementation of ...

  15. Vibration Control in Periodic Structures

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker


    Within the framework of periodic structures, the calibration of RL shunted piezoelectric inclusions is investigated with respect to maximum damping of a particular wave form. A finite element setting is assumed, with local shunted inclusions inside the unit cell. The effect of the shunts is repre....... The presentation contains dispersion diagrams and vibration amplitude curves for the optimally calibrated RL shunt system in a 1-D periodic structure with local piezoelectric inclusions....

  16. Numerical analysis using state space method for vibration control of ...

    African Journals Online (AJOL)


    Numerical analysis using state space method for vibration control of car seat by employing passive and semi active dampers. Udit S. Kotagi1, G.U. Raju1, V.B. Patil2, Krishnaraja G. Kodancha1*. 1Department of Mechanical Engineering, B.V. Bhoomaraddi College of Engineering & Technology, Hubli, Karnataka, INDIA.

  17. Active vibration control using DEAP actuators (United States)

    Sarban, Rahimullah; Jones, Richard W.


    Dielectric electro-active polymer (DEAP) is a new type of smart material, which has the potential to be used to provide effective actuation for a wide range of applications. The properties of DEAP material place it somewhere between those of piezoceramics and shape memory alloys. Of the range of DEAP-based actuators that have been developed those having a cylindrical configuration are among the most promising. This contribution introduces the use of a tubular type DEAP actuator for active vibration control purposes. Initially the DEAP-based tubular actuator to be used in this study, produced by Danfoss PolyPower A/S, is introduced along with the static and dynamic characteristics. Secondly an electromechanical model of the tubular actuator is briefly reviewed and its ability to model the actuator's hysteresis characteristics for a range of periodic input signals at different frequencies demonstrated. The model will be used to provide hysteresis compensation in future vibration isolation studies. Experimental active vibration control using the actuator is then examined, specifically active vibration isolation of a 250 g mass subject to shaker generated 'ground vibration'. An adaptive feedforward control strategy is used to achieve this. The ability of the tubular actuator to reject both tonal and broadband random vibratory disturbances is then demonstrated.

  18. Resonant vibration control of wind turbine blades

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker


    The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element....... The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes....

  19. Wind Turbine Rotors with Active Vibration Control

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann

    This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...... formulation. The element provides an accurate representation of the eigenfrequencies and whirling modes of the gyroscopic system, and identifies lightly damped edge-wise modes. By adoption of a method for active, collocated resonant vibration of multi-degree-of-freedom systems it is demonstrated...... that these are geometrically well separated. For active vibration control in three-bladed wind turbine rotors the present work presents a resonance-based method for groups of one collective and two whirling modes. The controller is based on the existing resonant format and introduces a dual system targeting the collective...

  20. Internal Temperature Control For Vibration Testers (United States)

    Dean, Richard J.


    Vibration test fixtures with internal thermal-transfer capabilities developed. Made of aluminum for rapid thermal transfer. Small size gives rapid response to changing temperatures, with better thermal control. Setup quicker and internal ducting facilitates access to parts being tested. In addition, internal flows smaller, so less energy consumed in maintaining desired temperature settings.

  1. Optimal control of vibrational transitions of HCl

    Indian Academy of Sciences (India)

    Control of fundamental and overtone transitions of a vibration are studied for the diatomic molecule, HCl. Specifically, the results of the effect of variation of the penalty factor on the physical attributes of the system (i.e., probabilities) and pulse (i.e., amplitudes) considering three different pulse durations for each value of the ...

  2. Downhole Vibration Monitoring and Control System

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern


    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. The key feature of this system is its use of a magnetorheological fluid (MRF) to allow the damping coefficient to be changed extensively, rapidly and reversibly without the use of mechanical valves, but only by the application of a current. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. Much of the effort was devoted to the design and testing of the MRF damper, itself. The principal objectives of Phase II were: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in a drilling laboratory. Phase II concluded on January 31, 2006, and a final report was issued. Work on Phase III of the project began during the first quarter, 2006, with the objectives of building precommercial prototypes, testing them in a drilling laboratory and the field; developing and implementing a commercialization plan. All of these have been accomplished. The Downhole Vibration Monitoring & Control System (DVMCS) prototypes have been successfully proven in testing at the TerraTek drilling facility and at the Rocky Mountain Oilfield Test Center (RMOTC.) Based on the results of these tests, we have signed a definitive development and distribution agreement with Smith, and commercial deployment is underway. This current version of the DVMCS monitors and controls axial vibrations. Due to time and budget constraints of this program, it was not possible to complete a system that would also deal with lateral and torsional (stick-slip) vibrations as originally planned; however, this effort is continuing without DOE

  3. A novel technique for active vibration control, based on optimal ...

    Indian Academy of Sciences (India)

    In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously ...

  4. A novel technique for active vibration control, based on optimal ...

    Indian Academy of Sciences (India)



    Jul 11, 2017 ... Abstract. In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a ...

  5. Comparison of a Vibrating Foam Roller and a Non-vibrating Foam Roller Intervention on Knee Range of Motion and Pressure Pain Threshold: A Randomized Controlled Trial. (United States)

    Cheatham, Scott W; Stull, Kyle R; Kolber, Morey J


    The use of foam rollers to provide soft-tissue massage has become a common intervention among health and fitness professionals. Recently, manufacturers have merged the science of vibration therapy and foam rolling with the development of vibrating foam rollers. To date, no peer reviewed investigations have been published on this technology. The purpose of this study was to compare the effects of a vibrating roller and non-vibrating roller intervention on prone knee flexion passive range of motion (ROM) and pressure pain thresholds (PPT) of the quadriceps musculature. Forty-five recreationally active adults were randomly allocated to one of three groups: vibrating roller, non-vibrating roller, and control. Each roll intervention lasted a total of 2 minutes. The control group did not roll. Dependent variables included prone knee flexion ROM and PPT measures. Statistical analysis included parametric and non-parametric tests to measure changes among groups. The vibrating roller demonstrated the greatest increase in PPT (180kPa, p< 0.001), followed by the non-vibrating roller (112kPa, p< 0.001), and control (61kPa, p<0.001). For knee ROM, the vibrating roller demonstrated the greatest increase in ROM (7 degrees, p< 0.001), followed by the non-vibrating roller (5 degrees, p< 0.001), and control (2 degrees, p<0.001). Between groups, there was significant difference in PPT between the vibrating and non-vibrating roller (p=.03) and vibrating roller and control (p<.001). There was also a significant difference between the non-vibrating roller and control (p<.001). For knee ROM, there was no significant difference between the vibrating and non-vibrating roller (p=.31). A significant difference was found between the vibrating roller and control group (p<.001) and non-vibrating roller and control (p<.001). The results suggest that a vibrating roller may increase an individual's tolerance to pain greater than a non-vibrating roller. This investigation should be considered

  6. Tiltrotor Vibration Reduction Through Higher Harmonic Control (United States)

    Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben


    The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5-scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing IP and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasional on-line recalculations of the system transfer matrix. HHC had only a small (usually beneficial) effect on blade loads but increased pitch link loads by 25%. No degradation in aeroelastic stability was noted for any of the conditions tested.

  7. Higher Harmonic Control for Tiltrotor Vibration Reduction (United States)

    Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben


    The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5- scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing 1P and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasion-al on-line recalculations of the system transfer matrix.

  8. Emerging trends in vibration control of wind turbines: a focus on a dual control strategy. (United States)

    Staino, Andrea; Basu, Biswajit


    The paper discusses some of the recent developments in vibration control strategies for wind turbines, and in this context proposes a new dual control strategy based on the combination and modification of two recently proposed control schemes. Emerging trends in the vibration control of both onshore and offshore wind turbines are presented. Passive, active and semi-active structural vibration control algorithms have been reviewed. Of the existing controllers, two control schemes, active pitch control and active tendon control, have been discussed in detail. The proposed new control scheme is a merger of active tendon control with passive pitch control, and is designed using a Pareto-optimal problem formulation. This combination of controllers is the cornerstone of a dual strategy with the feature of decoupling vibration control from optimal power control as one of its main advantages, in addition to reducing the burden on the pitch demand. This dual control strategy will bring in major benefits to the design of modern wind turbines and is expected to play a significant role in the advancement of offshore wind turbine technologies. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Active Vibration Control of a Flexible Structure Using Piezoceramic Actuators

    Directory of Open Access Journals (Sweden)

    J. Fei


    Full Text Available Considerable attention has been devoted recently to active vibration control using intelligent materials as actuators. This paper presents results on active control schemes for vibration suppression of flexible steel cantilever beam with bonded piezoelectric actuators. The PZT patches are surface bonded near the fixed end of flexible steel cantilever beam. The dynamic model of the flexible steel cantilever beam is derived. Active vibration control methods, strain rate feedback control (SRF, positive position feedback control (PPF are investigated and implemented using xPC Target real-time system. Experimental results demonstrate that the SRF control and PPF control achieve effective vibration suppression results of steel cantilever beam.

  10. Diesel engine torsional vibration control coupling with speed control system (United States)

    Guo, Yibin; Li, Wanyou; Yu, Shuwen; Han, Xiao; Yuan, Yunbo; Wang, Zhipeng; Ma, Xiuzhen


    The coupling problems between shafting torsional vibration and speed control system of diesel engine are very common. Neglecting the coupling problems sometimes lead to serious oscillation and vibration during the operation of engines. For example, during the propulsion shafting operation of a diesel engine, the oscillation of engine speed and the severe vibration of gear box occur which cause the engine is unable to operate. To find the cause of the malfunctions, a simulation model coupling the speed control system with the torsional vibration of deformable shafting is proposed and investigated. In the coupling model, the shafting is simplified to be a deformable one which consists of several inertias and shaft sections and with characteristics of torsional vibration. The results of instantaneous rotation speed from this proposed model agree with the test results very well and are successful in reflecting the real oscillation state of the engine operation. Furthermore, using the proposed model, the speed control parameters can be tuned up to predict the diesel engine a stable and safe running. The results from the tests on the diesel engine with a set of tuned control parameters are consistent with the simulation results very well.

  11. Compact integrated piezoelectric vibration control package (United States)

    Spangler, Ronald L., Jr.; Russo, Farla M.; Palombo, Daniel A.


    Using recent advances in small, surface-mount electronics, coupled with proprietary packaging techniques, ACX has developed the SmartPackTM. The design and realization of this self-contained, active piezoelectric control device are described in this paper. The SmartPack uses a local control architecture, consisting of two parallel, analog, positive position feedback (PPF) filters, along with nearly collocated piezo strain sensors and actuators, to control multiple structural vibration modes. A key issue is the management of waste heat from the power electronics required to drive the piezo actuators. This issue is addressed through thermal/electrical modeling of the packaged amplifier. The effectiveness of the device is demonstrated through multi-mode active damping on a 24 inch square plate.

  12. A new isolator for vibration control (United States)

    Behrooz, Majid; Sutrisno, Joko; Wang, Xiaojie; Fyda, Robert; Fuchs, Alan; Gordaninejad, Faramarz


    This study presents the feasibility of a new variable stiffness and damping isolator (VSDI) in an integrated vibratory system. The integrated system comprised of two VSDIs, a connecting plate and a mass. The proposed VSDI consists of a traditional steel-rubber vibration absorber, as the passive element, and a magneto-rheological elastomer (MRE), with a controllable (or variable) stiffness and damping, as the semi-active element. MREs' stiffness and damping properties can be altered by a magnetic field. Dynamic testing on this integrated system has been performed to investigate the effectiveness of the VSDIs for vibration control. Experimental results show significant shift in natural frequency, when activating the VSDIs. Transmissibility and natural frequency of the integrated system are obtained from properties of single device. The experimental and predicted results show good agreement between the values of the natural frequency of the system at both off and on states. However, system damping predictions are different from experimental results. This might be due to unforeseen effects of pre-stressed MREs and nonlinear material properties.

  13. Intelligent failure-proof control system for structural vibration

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Kazuo [Keio Univ., Yokohama (Japan). Faculty of Science and Technology; Oba, Takahiro [Keio Univ., Tokyo (Japan)


    With progress of technology in recent years, gigantism and complication such as high-rise buildings, nuclear reactors and so on have brought about new problems. Particularly, the safety and the reliability for damages in abnormal situations have become more important. Intelligent control systems which can judge whether the situation is normal or abnormal at real time and cope with these situations suitably are demanded. In this study, Cubic Neural Network (CNN) is adopted, which consists of the controllers possessing cubically some levels of information abstracting. In addition to the usual quantitative control, the qualitative control is used for the abnormal situations. And, by selecting a suitable controller, CNN can cope with the abnormal situation. In order to confirm the effectiveness of this system, the structural vibration control problems with sensory failure and elasto-plastic response are dealt with. As a result of simulations, it was demonstrated that CNN can cope with unexpected abnormal situations which are not considered in learning. (author)

  14. Compact Active Vibration Control System for a Flexible Panel (United States)

    Schiller, Noah H. (Inventor); Cabell, Randolph H. (Inventor); Perey, Daniel F. (Inventor)


    A diamond-shaped actuator for a flexible panel has an inter-digitated electrode (IDE) and a piezoelectric wafer portion positioned therebetween. The IDE and/or the wafer portion are diamond-shaped. Point sensors are positioned with respect to the actuator and measure vibration. The actuator generates and transmits a cancelling force to the panel in response to an output signal from a controller, which is calculated using a signal describing the vibration. A method for controlling vibration in a flexible panel includes connecting a diamond-shaped actuator to the flexible panel, and then connecting a point sensor to each actuator. Vibration is measured via the point sensor. The controller calculates a proportional output voltage signal from the measured vibration, and transmits the output signal to the actuator to substantially cancel the vibration in proximity to each actuator.

  15. Mechanical systems a unified approach to vibrations and controls

    CERN Document Server

    Gans, Roger F


    This essential textbook covers analysis and control of engineering mechanisms, which include almost any apparatus with moving parts used in daily life, from musical instruments to robots. The text  presents both vibrations and controls with considerable breadth and depth using a unified notation. It strikes a nice balance between the analytical and the practical.  This text contains enough material for a two semester sequence, but it can also be used in a single semester course combining the two topics. Mechanical Systems: A Unified Approach to Vibrations and Controls presents a common notation and approach to these closely related areas. Examples from the both vibrations and controls components are integrated throughout this text. This book also: ·         Presents a unified approach to vibrations and controls, including an excellent diagram that simultaneously discusses embedding classical vibrations (mechanical systems) in a discussion of models, inverse models, and open and closed loop control ...

  16. Resonant vibration control of three-bladed wind turbine rotors

    DEFF Research Database (Denmark)

    Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker


    Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...

  17. 'NASA Invention of the Year' Controls Noise and Vibration (United States)


    Developed at NASA's Langley Research Center, the Macro-Fiber Composite (MFC) is designed to control vibration, noise, and deflections in composite structural beams and panels. Smart Material Corporation specializes in the development of piezocomposite components, and licensed the MFC technology from Langley in 2002. To date, Smart Material Corporation has sold MFCs to over 120 customers, including such industry giants as Volkswagen, Toyota, Honda, BMW, General Electric, and the tennis company, HEAD. The company estimates that its customers have filed at least 100 patents for their various unique uses of the technology. In addition, the company's product portfolio has grown to include piezoceramic fibers and fiber composites, piezoceramic actuators and sensors, and test equipment for these products. It also offers a compact, lightweight power system for MFC testing and validation. Consumer applications already on the market include piezoelectric systems as part of audio speakers, phonograph cartridges and microphones, and recreational products requiring vibration control, such as skis, snowboards, baseball bats, hockey sticks, and tennis racquets.

  18. Innovation in Active Vibration Control Strategy of Intelligent Structures

    Directory of Open Access Journals (Sweden)

    A. Moutsopoulou


    Full Text Available Large amplitudes and attenuating vibration periods result in fatigue, instability, and poor structural performance. In light of past approaches in this field, this paper intends to discuss some innovative approaches in vibration control of intelligent structures, particularly in the case of structures with embedded piezoelectric materials. Control strategies are presented, such as the linear quadratic control theory, as well as more advanced theories, such as robust control theory. The paper presents sufficiently a recognizable advance in knowledge of active vibration control in intelligent structures.

  19. Vibration Control via Stiffness Switching of Magnetostrictive Transducers (United States)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.


    This paper presents a computational study of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magnetomechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.25; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping.

  20. Inhibiting multiple mode vibration in controlled flexible systems (United States)

    Hyde, James M.; Chang, Kenneth W.; Seering, Warren P.


    Viewgraphs on inhibiting multiple mode vibration in controlled flexible systems are presented. Topics covered include: input pre-shaping background; developing multiple-mode shapers; Middeck Active Control Experiment (MACE) test article; and tests and results.

  1. Optimal Vibration Control for Tracked Vehicle Suspension Systems

    Directory of Open Access Journals (Sweden)

    Yan-Jun Liang


    Full Text Available Technique of optimal vibration control with exponential decay rate and simulation for vehicle active suspension systems is developed. Mechanical model and dynamic system for a class of tracked vehicle suspension vibration control is established and the corresponding system of state space form is described. In order to prolong the working life of suspension system and improve ride comfort, based on the active suspension vibration control devices and using optimal control approach, an optimal vibration controller with exponential decay rate is designed. Numerical simulations are carried out, and the control effects of the ordinary optimal controller and the proposed controller are compared. Numerical simulation results illustrate the effectiveness of the proposed technique.

  2. Nonlinear vibration with control for flexible and adaptive structures

    CERN Document Server

    Wagg, David


    This book provides a comprehensive discussion of nonlinear multi-modal structural vibration problems, and shows how vibration suppression can be applied to such systems by considering a sample set of relevant control techniques. It covers the basic principles of nonlinear vibrations that occur in flexible and/or adaptive structures, with an emphasis on engineering analysis and relevant control techniques. Understanding nonlinear vibrations is becoming increasingly important in a range of engineering applications, particularly in the design of flexible structures such as aircraft, satellites, bridges, and sports stadia. There is an increasing trend towards lighter structures, with increased slenderness, often made of new composite materials and requiring some form of deployment and/or active vibration control. There are also applications in the areas of robotics, mechatronics, micro electrical mechanical systems, non-destructive testing and related disciplines such as structural health monitoring. Two broader ...

  3. Vibrational Excitation Can Control Tropospheric Chemistry

    National Research Council Canada - National Science Library

    Geoffrey Tyndall


    .... However, on page 1066 of this issue, Glowacki et al. show that a strikingly different product distribution can be obtained in the oxidation of acetylene depending on whether the radicals contain high amounts of internal (vibrational...

  4. Rail Vehicle Vibrations Control Using Parameters Adaptive PID Controller

    Directory of Open Access Journals (Sweden)

    Muzaffer Metin


    Full Text Available In this study, vertical rail vehicle vibrations are controlled by the use of conventional PID and parameters which are adaptive to PID controllers. A parameters adaptive PID controller is designed to improve the passenger comfort by intuitional usage of this method that renews the parameters online and sensitively under variable track inputs. Sinusoidal vertical rail misalignment and measured real rail irregularity are considered as two different disruptive effects of the system. Active vibration control is applied to the system through the secondary suspension. The active suspension application of rail vehicle is examined by using 5-DOF quarter-rail vehicle model by using Manchester benchmark dynamic parameters. The new parameters of adaptive controller are optimized by means of genetic algorithm toolbox of MATLAB. Simulations are performed at maximum urban transportation speed (90 km/h of the rail vehicle with ±5% load changes of rail vehicle body to test the robustness of controllers. As a result, superior performance of parameters of adaptive controller is determined in time and frequency domain.

  5. Vibration mode shape control by prestressing (United States)

    Holnicki-Szulc, Jan; Haftka, Raphael T.


    A procedure is described for reducing vibration at sensitive locations on a structure, by induced distortions. The emphasis is placed on the excitation in a narrow frequency band, so that only a small number of vibration modes contribute to the intensity of the forced response. The procedure is demonstrated on an antenna truss example, showing that, with repeated frequencies, it is very easy to move nodal lines of one of the modes.

  6. Magnetostrictively actuated control flaps for vibration reduction in helicopter rotors

    Energy Technology Data Exchange (ETDEWEB)

    Millott, T.; Friedmann, P.P. [Univ. of California, Los Angeles, CA (United States). Mechanical, Aerospace and Nuclear Engineering Dept.


    High vibration levels can impose constraints on helicopter operations and hinder passenger acceptance. Vibration reduction using blade root pitch control introduces a significant power penalty and may adversely affect the airworthiness of the flight control system. Comparable levels of vibration reduction can be achieved using considerably less power through an actively controlled trailing edge flap mounted on the blade. Such a device would have no effect on helicopter airworthiness since it is controlled by a loop separate from the primary flight control system which utilizes the swashplate. Control flap actuation using the magnetostrictive material Terfenol-D is studied in this paper by designing a minimum weight actuator, subject to a set of actuation and stress constraints. The resulting device is capable of producing vibration reduction in excess of 90% at cruise conditions.

  7. Virtual Shaker Testing: Simulation Technology Improves Vibration Test Performance (United States)

    Ricci, Stefano; Peeters, Bart; Fetter, Rebecca; Boland, Doug; Debille, Jan


    In the field of vibration testing, the interaction between the structure being tested and the instrumentation hardware used to perform the test is a critical issue. This is particularly true when testing massive structures (e.g. satellites), because due to physical design and manufacturing limits, the dynamics of the testing facility often couples with the test specimen one in the frequency range of interest. A further issue in this field is the standard use of a closed loop real-time vibration control scheme, which could potentially shift poles and change damping of the aforementioned coupled system. Virtual shaker testing is a novel approach to deal with these issues. It means performing a simulation which closely represents the real vibration test on the specific facility by taking into account all parameters which might impact the dynamic behavior of the specimen. In this paper, such a virtual shaker testing approach is developed. It consists of the following components: (1) Either a physical-based or an equation-based coupled electro-mechanical lumped parameter shaker model is created. The model parameters are obtained from manufacturer's specifications or by carrying out some dedicated experiments; (2) Existing real-time vibration control algorithm are ported to the virtual simulation environment; and (3) A structural model of the test object is created and after defining proper interface conditions structural modes are computed by means of the well-established Craig-Bampton CMS technique. At this stage, a virtual shaker test has been run, by coupling the three described models (shaker, control loop, structure) in a co-simulation routine. Numerical results have eventually been correlated with experimental ones in order to assess the robustness of the proposed methodology.

  8. Summary of semi-initiative and initiative control automobile engine vibration (United States)

    Qu, Wei; Qu, Zhou


    Engine vibration accounts for around 55% of automobile vibration, separating the engine vibration from transmitting to automobile to the utmost extent is significant for improving NVH performance. Semi-initiative and initiative control of engine vibration is one of the hot spots of technical research in domestic and foreign automobile industry, especially luxury automobiles which adopt this technology to improve amenity and competitiveness. This article refers to a large amount of domestic and foreign related materials, fully introduces the research status of semi-initiative and initiative control suspension of engine vibration suspension and many kinds of structural style, and provides control policy and method of semi-initiative and initiative control suspension system. Compare and analyze the structural style of semi-initiative and initiative control and merits and demerits of current structures of semi-initiative and initiative control of mechanic electrorheological, magnetorheological, electromagnetic actuator, piezoelectric ceramics, electrostriction material, pneumatic actuator etc. Models of power assembly mounting system was classified.Calculation example indicated that reasonable selection of engine mounting system parameters is useful to reduce engine vibration transmission and to increase ride comfort. Finally we brought forward semi-initiative and initiative suspension which might be applied for automobiles, and which has a promising future.

  9. Integrated cable vibration control system using wireless sensors (United States)

    Jeong, Seunghoo; Cho, Soojin; Sim, Sung-Han


    As the number of long-span bridges is increasing worldwide, maintaining their structural integrity and safety become an important issue. Because the stay cable is a critical member in most long-span bridges and vulnerable to wind-induced vibrations, vibration mitigation has been of interest both in academia and practice. While active and semi-active control schemes are known to be quite effective in vibration reduction compared to the passive control, requirements for equipment including data acquisition, control devices, and power supply prevent a widespread adoption in real-world applications. This study develops an integrated system for vibration control of stay-cables using wireless sensors implementing a semi-active control. Arduino, a low-cost single board system, is employed with a MEMS digital accelerometer and a Zigbee wireless communication module to build the wireless sensor. The magneto-rheological (MR) damper is selected as a damping device, controlled by an optimal control algorithm implemented on the Arduino sensing system. The developed integrated system is tested in a laboratory environment using a cable to demonstrate the effectiveness of the proposed system on vibration reduction. The proposed system is shown to reduce the vibration of stay-cables with low operating power effectively.

  10. Active control of noise radiation from vibrating structures

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    The thesis is concerned with the active control of randomly vibrating structures by means of feedback control, with particular emphasis on reducing the sound radiation from such structures. A time domain model of the structural and radiation dynamics of an actively controlled plate has been...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...... developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...

  11. Vibration Control via Stiffness Switching of Magnetostrictive Transducers (United States)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.


    In this paper, a computational study is presented of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magneto-mechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.13; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping. For the cases considered, optimal resistive shunt damping performed considerably better than both voltage- and shunt-controlled stiffness switching.


    Directory of Open Access Journals (Sweden)

    В. Макаренко


    Full Text Available In the article the control system is created, which is able to reduce steady-state vibration response of thinwalled flexible structure in the wide band of low frequencies. It is supposed, that the flexible structure is subject to external harmonic force with variable frequencies, and parameters of that force are available for the usage by the control system. The control system is based on pattern search algorithm and suggestion about the dependence of signal, which is formed by the control system, from the steady-state vibration response of the flexible structure. Developed software allows to use pattern search algorithm as the control system for plate vibration in real-time. The influence on control system operation of signal delay of executive device of compensating path and transition process after the change of control signal parameters is done by the usage of the additional idle time. During idle time the control signal is supported. It has parameters that have taken place before the beginning of idle mode. Step reset option for resuming of search after the long-term steady-state vibration of flexible structure do not derange control system operation, because step change take place only after polling cycle termination. The efficiency of proposed system is illustrated experimentally on the example of clamped plate. Experimental results analysis showed the necessity of multiple compensating devices application for vibration reduction in wide frequency range.

  13. Analysis of Piezoelectric Actuator for Vibration Control of Composite plate (United States)

    Gomaa, Ahmed R.; Hai, Huang


    Vibration analysis is studied numerically in this paper for a simply supported composite plate subjected to external loadings. Vibrations are controlled by using piezoelectric patches. Finite element method (ANSYS) is used for obtaining finite element model of the smart plate structure, a layered composite plate is manufactured experimentally and tested to obtain the structure mechanical properties. Different piezoelectric patch areas and different applied gain voltage effects on vibration attenuation is studied. The numerical solution is compared with the experimental work, a good agreement achieved.

  14. MR Damper Controlled Vibration Absorber for Enhanced Mitigation of Harmonic Vibrations

    Directory of Open Access Journals (Sweden)

    Felix Weber


    Full Text Available This paper describes a semi-active vibration absorber (SVA concept based on a real-time controlled magnetorheological damper (MR-SVA for the enhanced mitigation of structural vibrations due to harmonic disturbing forces. The force of the MR damper is controlled in real-time to generate the frequency and damping controls according to the behaviour of the undamped vibration absorber for the actual frequency of vibration. As stiffness and damping emulations in semi-active actuators are coupled quantities the control is formulated to prioritize the frequency control by the controlled stiffness. The control algorithm is augmented by a stiffness correction method ensuring precise frequency control when the desired control force is constrained by the semi-active restriction and residual force of the MR damper. The force tracking task is solved by a model-based feed forward with feedback correction. The MR-SVA is numerically and experimentally validated for the primary structure with nominal eigenfrequency and when de-tuning of −10%, −5%, +5% and +10% is present. Both validations demonstrate that the MR-SVA improves the vibration reduction in the primary structure by up to 55% compared to the passive tuned mass damper (TMD. Furthermore, it is shown that the MR-SVA with only 80% of tuned mass leads to approximately the same enhanced performance while the associated increased relative motion amplitude of the tuned mass is more than compensated be the reduced dimensions of the mass. Therefore, the MR-SVA is an appropriate solution for the mitigation of tall buildings where the pendulum mass can be up to several thousands of metric tonnes and space for the pendulum damper is limited.

  15. The CFVib Experiment: Control of Fluids in Microgravity with Vibrations (United States)

    Fernandez, J.; Sánchez, P. Salgado; Tinao, I.; Porter, J.; Ezquerro, J. M.


    The Control of Fluids in Microgravity with Vibrations (CFVib) experiment was selected for the 2016 Fly Your Thesis! programme as part of the 65th ESA Parabolic Flight Campaign. The aim of the project is to observe the potentially complex behaviour of vibrated liquids in weightless environments and to investigate the extent to which small-amplitude vibrations can be used to influence and control this behaviour. Piezoelectric materials are used to generate high-frequency vibrations to drive surface waves and large-scale reorientation of the interface. The theory of vibroequilibria, which treats the quasi-stationary surface configurations achieved by this reorientation, was used to predict interesting parameter regimes and interpret fluid behaviour. Here we describe the scientific motivation, objectives, and design of the experiment.

  16. Research of vibration controlling based on programmable logic controller for electrostatic precipitator (United States)

    Zhang, Zisheng; Li, Yanhu; Li, Jiaojiao; Liu, Zhiqiang; Li, Qing


    In order to improve the reliability, stability and automation of electrostatic precipitator, circuits of vibration motor for ESP and vibration control ladder diagram program are investigated using Schneider PLC with high performance and programming software of Twidosoft. Operational results show that after adopting PLC, vibration motor can run automatically; compared with traditional control system of vibration based on single-chip microcomputer, it has higher reliability, better stability and higher dust removal rate, when dust emission concentrations <= 50 mg m-3, providing a new method for vibration controlling of ESP.

  17. Cooperative Control Method of Active and Semiactive Control: New Framework for Vibration Control


    Kazuhiko Hiramoto


    A new control design framework for vibration control, the cooperative control of active and semiactive control, is proposed in the paper. In the cooperative control, a structural system having both of an actuator and a semiactive control device, for example, MR damper and so forth, is defined as the control object. In the proposed control approach, the higher control performance is aimed by the cooperative control between the active control with the actuator and the semiactive control with th...

  18. Passive and Active Vibration Control of Renewable Energy Structures

    DEFF Research Database (Denmark)

    Zhang, Zili

    The present thesis deals with fundamental researches on passive and active vibration control of renewable energy structures, and provides useful models for practical applications. Effective and robust vibration control methods have been explored for mitigating the lightly damped edgewise blade...... solutions for wave energy point absorbers, in order to maximize the mean absorbed power and to deliver more smooth power to the grid. A novel suboptimal causal control law has been established for controlling the motion of the point absorber, and a new type of point absorber has also been proposed...

  19. Development and evaluation of a generic active helicopter vibration controller (United States)

    Davis, M. W.


    A computerized generic active controller is developed, which alleviates helicopter vibration by closed-loop implementation of higher harmonic control (HHC). In the system, the higher harmonic blade pitch is input through a standard helicopter swashplate; for a four-blade helicopter rotor the 4/rev vibration in the rotorcraft is minimized by inducing cyclic pitch motions at 3, 4, and 5/rev in the rotating system. The controller employs the deterministic, cautious, and dual control approaches and two linear system models (local and global), as well as several methods of limiting control. Based on model testing, performed at moderate to high values of forward velocity and rotor thrust, reductions in the rotor test apparatus vibration from 75 to 95 percent are predicted, with HHC pitch amplitudes of less than one degree. Good performance is also noted for short-duration maneuvers.

  20. A Novel Control System Design for Vibrational MEMS Gyroscopes

    Directory of Open Access Journals (Sweden)

    Qing Zheng


    Full Text Available There are two major control problems associated with vibrational MEMS gyroscopes: to control two vibrating axes (or modes of the gyroscope, and to estimate a time-varying rotation rate. This paper demonstrates how a novel active disturbance rejection control addresses these problems in the presence of the mismatch of natural frequencies between two axes, mechanical-thermal noises, Quadrature errors, and parameter variations. A demodulation approach based on the estimated dynamics of the system by an extended state observer is used to estimate the rotation rate. The simulation results on a Z-axis MEMS gyroscope show that the controller is very effective by driving the output of the drive axis to a desired trajectory, forcing the vibration of the sense axis to zero for a force-to-rebalance operation and precisely estimating the rotation rate.

  1. 10th International Conference on Vibration Engineering and Technology of Machinery

    CERN Document Server


    The VETOMAC-X Conference covered a holistic plethora of relevant topics in vibration and engineering technology including condition monitoring, machinery and structural dynamics, rotor dynamics,  experimental techniques, finite element model updating, industrial case studies, vibration control and energy harvesting, and signal processing. These proceedings contain not only all of the nearly one-hundred peer-reviewed presentations from authors representing more than twenty countries, but also include six invited lectures from renowned experts: Professor K. Gupta, Mr W. Hahn, Professor A.W. Lees, Professor John Mottershead, Professor J.S. Rao, and Dr P. Russhard. This work is of interest to researchers and practitioners alike, and is an essential book for most of libraries of higher academic institutes.

  2. Rotor position and vibration control for aerospace flywheel energy storage devices and other vibration based devices (United States)

    Alexander, B. X. S.

    Flywheel energy storage has distinct advantages over conventional energy storage methods such as electrochemical batteries. Because the energy density of a flywheel rotor increases quadratically with its speed, the foremost goal in flywheel design is to achieve sustainable high speeds of the rotor. Many issues exist with the flywheel rotor operation at high and varying speeds. A prominent problem is synchronous rotor vibration, which can drastically limit the sustainable rotor speed. In a set of projects, the novel Active Disturbance Rejection Control (ADRC) is applied to various problems of flywheel rotor operation. These applications include rotor levitation, steady state rotation at high speeds and accelerating operation. Several models such as the lumped mass model and distributed three-mass models have been analyzed. In each of these applications, the ADRC has been extended to cope with disturbance, noise, and control effort optimization; it also has been compared to various industry-standard controllers such as PID and PD/observer, and is proven to be superior. The control performance of the PID controller and the PD/observer currently used at NASA Glenn has been improved by as much as an order of magnitude. Due to the universality of the second order system, the results obtained in the rotor vibration problem can be straightforwardly extended to other vibrational systems, particularly, the MEMS gyroscope. Potential uses of a new nonlinear controller, which inherits the ease of use of the traditional PID, are also discussed.

  3. Performance evaluation on vibration control of MR landing gear

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D Y; Nam, Y J; Park, M K [Graduate School, Pusan National University, Busan 609-735 (Korea, Republic of); Yamane, R [Kokushikan University, 4-28-1 Setagaya, Setagaya-ku, Tokyo 154-8515 (Japan)], E-mail:, E-mail:


    This paper is concerned with the applicability of the developed MR damper to the landing gear system for the attenuating undesired shock and vibration in the landing and taxing phases. First of all, the experimental model of the MR damper is derived based on the results of performance evaluations. Next, a simplified skyhook controller, which is one of the most straightforward, but effective approaches for improving ride comport in vehicles with active suspensions, is formulated. Then, the vibration control performances of the landing gear system using the MR damper are theoretically evaluated in the landing phase of the aircraft. A series of simulation analyses show that the proposed MR damper with the skyhook controller is effective for suppressing undesired vibration of the aircraft body. Finally, the effectiveness of the simulation results are additionally verified via HILS (Hardware-in-the-loop-simulation) method.

  4. Smart helicopter rotors optimization and piezoelectric vibration control

    CERN Document Server

    Ganguli, Ranjan; Viswamurthy, Sathyamangalam Ramanarayanan


    Exploiting the properties of piezoelectric materials to minimize vibration in rotor-blade actuators, this book demonstrates the potential of smart helicopter rotors to achieve the smoothness of ride associated with jet-engined, fixed-wing aircraft. Vibration control is effected using the concepts of trailing-edge flaps and active-twist. The authors’ optimization-based approach shows the advantage of multiple trailing-edge flaps and algorithms for full-authority control of dual trailing-edge-flap actuators are presented. Hysteresis nonlinearity in piezoelectric stack actuators is highlighted and compensated by use of another algorithm. The idea of response surfaces provides for optimal placement of trailing-edge flaps. The concept of active twist involves the employment of piezoelectrically induced shear actuation in rotating beams. Shear is then demonstrated for a thin-walled aerofoil-section rotor blade under feedback-control vibration minimization. Active twist is shown to be significant in reducing vibra...

  5. Modeling of Axial Spring Stiffness in Active Vibration Controlled Drilling

    Directory of Open Access Journals (Sweden)

    Pao William


    Full Text Available During drilling process, substantial amount of vibration and shock are induced to the drill string. Active vibration controlled drilling is introduced to reduce the vibration and increase the efficiency of drilling process. In this system, two main components that determine the damping coefficient are magnetorheological (MR damper and spring assembly. Performance of vibration damping system is depending on the viscosity of MR fluid in the damper and spring constant of spring assembly. One of the key issues that are unclear from the design is the correlation between the axial spring stiffness configuration and the damping force which needs to be tuned actively. There has been lack of studies on how the viscosity of MR fluid on the active vibration damper affects the damping stiffness of the whole system. The objective of the project is to extract the correlations for the viscous damping coefficient, equivalent spring stiffness and power input to the system. Simplified vibration model is thus created using Simulink, together with experimental data fed from APS Technology’s in-house team. Inputs of the simulation such as force exerted, mass of mandrel, spring constant and step time are based on the experimental data and can be adjusted to suit different experiments. By having the model, behavior of the system can be studied and analyzed. From the simulation, it is also observed that the relationship between damping coefficient and power input of the system is linear.

  6. A novel technique for active vibration control, based on optimal tracking control (United States)

    Kheiri Sarabi, Behrouz; Sharma, Manu; Kaur, Damanjeet


    In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously tracking zero references for modes of vibration. To illustrate the technique, a two-degrees of freedom spring-mass-damper system is considered as a test system. The mathematical model of the system is derived and then converted into a state-space model. A linear quadratic tracking control law is then used to make the disturbed system track zero references.

  7. Gel performance in rheology and profile control under low-frequency vibration: coupling application of physical and chemical EOR techniques. (United States)

    Zheng, Li Ming; Pu, Chun Sheng; Liu, Jing; Ma, Bo; Khan, Nasir


    Flowing gel plugging and low-frequency vibration oil extraction technology have been widely applied in low-permeability formation. High probability of overlapping in action spheres of two technologies might lead to poor operating efficiency during gel injection. Study on flowing gel rheological properties under low-frequency vibration was essential, which was carried out indoor with viscosity measurement. Potential dynamic mechanisms were analyzed for the rheological variation. Under low-frequency vibration, gel rheological properties were found to be obviously influenced, with vibration delaying gel cross-linking in induction period, causing a two-stage gel viscosity change in acceleration period, and decreasing gel strength in stable period. Surface of gel system under vibration presented different fluctuating phenomenon from initial harmonic vibrating to heterogeneous fluctuating (droplet separation might appear) to final harmonic vibrating again. Dynamic displacement in unconsolidated sand pack revealed that low-frequency vibration during gel injection might be a measure to achieve deep profile control, with the gel injection depth increased by 65.8 % compared with the vibration-free sample. At last, suggestions for field test were given in the paper to achieve lower injection friction and better gel plugging efficiency.

  8. Adaptive Semiactive Cable Vibration Control: A Frequency Domain Perspective

    Directory of Open Access Journals (Sweden)

    Z. H. Chen


    Full Text Available An adaptive solution to semiactive control of cable vibration is formulated by extending the linear quadratic Gaussian (LQG control from time domain to frequency domain. Frequency shaping is introduced via the frequency dependent weights in the cost function to address the control effectiveness and robustness. The Hilbert-Huang transform (HHT technique is further synthesized for online tuning of the controller gain adaptively to track the cable vibration evolution, which also obviates the iterative optimal gain selection for the trade-off between control performance and energy in the conventional time domain LQG (T-LQG control. The developed adaptive frequency-shaped LQG (AF-LQG control is realized by collocated self-sensing magnetorheological (MR dampers considering the nonlinear damper dynamics for force tracking control. Performance of the AF-LQG control is numerically validated on a bridge cable transversely attached with a self-sensing MR damper. The results demonstrate the adaptivity in gain tuning of the AF-LQG control to target for the dominant cable mode for vibration energy dissipation, as well as its enhanced control efficacy over the optimal passive MR damping control and the T-LQG control for different excitation modes and damper locations.

  9. Technologies for Legionella Control (United States)

    Presentation includes a review of new Office of Water document entitled "Technologies for Legionella Control in Premise Plumbing Systems", and discussion on ORD research projects involving Legionella and disinfection.

  10. Adaptive control of an active seat for occupant vibration reduction (United States)

    Gan, Zengkang; Hillis, Andrew J.; Darling, Jocelyn


    The harmful effects on human performance and health caused by unwanted vibration from vehicle seats are of increasing concern. This paper presents an active seat system to reduce the vibration level transmitted to the seat pan and the occupants' body under low frequency periodic excitation. Firstly, the detail of the mechanical structure is given and the active seat dynamics without external load are characterized by vibration transmissibility and frequency responses under different excitation forces. Owing the nonlinear and time-varying behaviour of the proposed system, a Filtered-x least-mean-square (FXLMS) adaptive control algorithm with on-line Fast-block LMS (FBLMS) identification process is employed to manage the system operation for high vibration cancellation performance. The effectiveness of the active seat system is assessed through real-time experimental tests using different excitation profiles. The system identification results show that an accurate estimation of the secondary path is achieved by using the FBLMS on-line technique. Substantial reduction is found for cancelling periodic vibration containing single and multiple frequencies. Additionally, the robustness and stability of the control system are validated through transient switching frequency tests.

  11. Optimal control of vibrational transitions of HCl

    Indian Academy of Sciences (India)


    1]. Lasers have the advantage of depositing energy in a non-statistical fashion. Shaped femtosecond laser pulses, due to technological advance- ment of lasers, can be employed as a new class of reagents to alter the course ...

  12. VibroCav : Hydrodynamic Vibration and Cavitation Technology

    NARCIS (Netherlands)

    Bakker, T.W.


    Vibration and cavitation can be generated in many ways and serve many useful purposes. This study describes physical aspects of useful vibration and cavitation for a broad spectrum of applications at atmospheric or elevated pressures. After a review of available devices, hydrodynamic

  13. Vibrating membrane filtration as improved technology for microalgae dewatering. (United States)

    Nurra, Claudia; Clavero, Ester; Salvadó, Joan; Torras, Carles


    The effect of shear-enhanced filtration by vibratory process in microalgae dewatering is presented in this paper. The aim of this research was to investigate the technical performance and improvement of vibrating membrane filtration compared with conventional tangential cross-flow filtration in microalgae concentration. An industrial-scale available commercial set-up was used. Several membrane materials as polyethersulfone, polyacrylonitrile, etc., and mean pore sizes (from 7000Da to 0.2μm) were tested and compared in both filtration set-ups. Experiments were carried-out with Nannochloropsis gaditana and Phaeodactylum tricornutum microalgae. It has been demonstrated that, even if the choice of the membrane depends on its cut-off, its material and the type of microalgae filtrated, dynamic filtration is always the best technology over a conventional one. If with conventional filtration permeability values were in the vicinity of 10L/h/m(2)/bar in steady state phase, with dynamic filtration these values increased to 30L/h/m(2)/bar or more. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Quantum control of vibrational excitations in a heteronuclear ...

    Indian Academy of Sciences (India)


    Quantum control of vibrational excitations in a heteronuclear diatomic molecule. SITANSH SHARMA, PURSHOTAM SHARMA and HARJINDER SINGH* ... electric field is calculated and used for the subsequent quantum dynamics, within the dipole approxima- tion. ... properties of interference of dynamical paths to regulate ...

  15. Quantum control of vibrational excitations in a heteronuclear ...

    Indian Academy of Sciences (India)

    Optimal control theory is applied to obtain infrared laser pulses for selective vibrational excitation in a heteronuclear diatomic molecule. The problem of finding the optimized field is phrased as a maximization of a cost functional which depends on the laser field. A time dependent Gaussian factor is introduced in the field ...

  16. Use of electro-magnetic damping for vibration control

    DEFF Research Database (Denmark)

    Stein, George Juraj; Darula, Radoslav; Sorokin, Sergey


    Vibration of machines is an unwanted phenomenon, and it is usually of interest to eliminate it. There are various means to be used in order to reach the goal, where the utilization of the electromagnet augmented by an external shunt circuit is analyzed in the paper. The magnetic force is used...... to introduce additional electromagnetic damping into vibrating mechanical system. The hysteretic losses and eddy currents are included in the model, to take into account more realistic dynamic behaviour of the system. The mathematical model of the controller is derived using lumped parameter approach...

  17. Vibration control of active structures an introduction

    CERN Document Server

    Preumont, Andre


    This text is an introduction to the dynamics of active structures and to the feedback control of lightly damped flexible structures. The emphasis is placed on basic issues and simple control strategies that work.

  18. A Family of Resonant Vibration Control Formats

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    Resonant control makes use of a controller with a resonance frequency and an equivalent damping ratio. A simple explicit calibration procedure is presented for a family of resonant controllers in which the frequency is tuned to the natural frequency of the targeted mode in such a way that the two...

  19. Optimization procedure to control the coupling of vibration modes in flexible space structures (United States)

    Walsh, Joanne L.


    As spacecraft structural concepts increase in size and flexibility, the vibration frequencies become more closely-spaced. The identification and control of such closely-spaced frequencies present a significant challenge. To validate system identification and control methods prior to actual flight, simpler space structures will be flown. To challenge the above technologies, it will be necessary to design these structures with closely-spaced or coupled vibration modes. Thus, there exists a need to develop a systematic method to design a structure which has closely-spaced vibration frequencies. This paper describes an optimization procedure which is used to design a large flexible structure to have closely-spaced vibration frequencies. The procedure uses a general-purpose finite element analysis program for the vibration and sensitivity analyses and a general-purpose optimization program. Results are presented from two studies. The first study uses a detailed model of a large flexible structure to design a structure with one pair of closely-spaced frequencies. The second study uses a simple equivalent beam model of a large flexible structure to obtain a design with two pairs of closely-spaced frequencies.

  20. Tuning of active vibration controllers for ACTEX by genetic algorithm (United States)

    Kwak, Moon K.; Denoyer, Keith K.


    This paper is concerned with the optimal tuning of digitally programmable analog controllers on the ACTEX-1 smart structures flight experiment. The programmable controllers for each channel include a third order Strain Rate Feedback (SRF) controller, a fifth order SRF controller, a second order Positive Position Feedback (PPF) controller, and a fourth order PPF controller. Optimal manual tuning of several control parameters can be a difficult task even though the closed-loop control characteristics of each controller are well known. Hence, the automatic tuning of individual control parameters using Genetic Algorithms is proposed in this paper. The optimal control parameters of each control law are obtained by imposing a constraint on the closed-loop frequency response functions using the ACTEX mathematical model. The tuned control parameters are then uploaded to the ACTEX electronic control electronics and experiments on the active vibration control are carried out in space. The experimental results on ACTEX will be presented.

  1. A data driven control method for structure vibration suppression (United States)

    Xie, Yangmin; Wang, Chao; Shi, Hang; Shi, Junwei


    High radio-frequency space applications have motivated continuous research on vibration suppression of large space structures both in academia and industry. This paper introduces a novel data driven control method to suppress vibrations of flexible structures and experimentally validates the suppression performance. Unlike model-based control approaches, the data driven control method designs a controller directly from the input-output test data of the structure, without requiring parametric dynamics and hence free of system modeling. It utilizes the discrete frequency response via spectral analysis technique and formulates a non-convex optimization problem to obtain optimized controller parameters with a predefined controller structure. Such approach is then experimentally applied on an end-driving flexible beam-mass structure. The experiment results show that the presented method can achieve competitive disturbance rejections compared to a model-based mixed sensitivity controller under the same design criterion but with much less orders and design efforts, demonstrating the proposed data driven control is an effective approach for vibration suppression of flexible structures.

  2. Semi-active vibration control in cable-stayed bridges under the condition of random wind load (United States)

    Heo, G.; Joonryong, Jeon


    This paper aims at an experimental study on the real-time vibration control of bridge structures using a semi-active vibration control method that has been in the spotlight recently. As structures are becoming larger and larger, structural harmful vibration caused by unspecified external forces such as earthquakes, gusts of wind, and collisions has been brought to attention as an important issue. These harmful vibrations can cause not only user anxiety but also severe structural damage or even complete failure of structures. Therefore, in view of structural safety and economical long-term maintenance, real-time control technology of the harmful structural vibration is urgently required. In this paper, a laboratory-scale model of a cable-stayed bridge was built, and a shear-type MR damper and a semi-active vibration control algorithm (Lyapunov and clipped optimal) were applied for the control of harmful vibration of the model bridge, in real time. On the basis of the test results, each semi-active control algorithm was verified quantitatively.

  3. Stiffness control of magnetorheological gels for adaptive tunable vibration absorber (United States)

    Kim, Hyun Kee; Kim, Hye Shin; Kim, Young-Keun


    In this study, a stiffness feedback control system for magnetorheological (MR) gel—a smart material of variable stiffness—is proposed, toward the design of a tunable vibration absorber that can adaptively tune to a time varying disturbance in real time. A PID controller was designed to track the required stiffness of the MR gel by controlling the magnitude of the target external magnetic field pervading the MR gel. This paper proposes a novel magnetic field generator that could produce a variable magnetic field with low energy consumption. The performance of the MR gel stiffness control was validated through experiments that showed the MR gel absorber system could be automatically tuned from 56 Hz to 67 Hz under a field of 100 mT to minimize the vibration of the primary system.

  4. Actively Controlled Landing Gear for Aircraft Vibration Reduction (United States)

    Horta, Lucas G.; Daugherty, Robert H.; Martinson, Veloria J.


    Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads using actively controlled landing gears. A facility has been developed to test various active landing gear control concepts and their performance. The facility uses a NAVY A6-intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented including modifications to actuate the gear externally and test data is used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  5. ER fluid applications to vibration control devices and an adaptive neural-net controller (United States)

    Morishita, Shin; Ura, Tamaki


    Four applications of electrorheological (ER) fluid to vibration control actuators and an adaptive neural-net control system suitable for the controller of ER actuators are described: a shock absorber system for automobiles, a squeeze film damper bearing for rotational machines, a dynamic damper for multidegree-of-freedom structures, and a vibration isolator. An adaptive neural-net control system composed of a forward model network for structural identification and a controller network is introduced for the control system of these ER actuators. As an example study of intelligent vibration control systems, an experiment was performed in which the ER dynamic damper was attached to a beam structure and controlled by the present neural-net controller so that the vibration in several modes of the beam was reduced with a single dynamic damper.

  6. Fuzzy Semiactive Vibration Control of Structures Using Magnetorheological Elastomer

    Directory of Open Access Journals (Sweden)

    Xuan Bao Nguyen


    Full Text Available In this research, a novel variable stiffness vibration isolator that uses magnetorheological elastomers (MREs accompanied with a fuzzy semiactive vibration control was developed. Firstly, the viscoelastic characteristics of MREs in shear mode were clarified systematically in order to achieve a mathematical basis for the controller development. Secondly, the fuzzy semiactive vibration control with a strategy based on the Lyapunov theory and dynamic characteristic of MREs was proposed for minimizing the movement of the isolator. In the conventional semiactive algorithm, the command applied current of MRE-based isolator is set at either minimum or maximum value which causes high acceleration and jerk peaks periodically, thus leading to the degeneration of the overall system quality. However, the fuzzy semiactive algorithm presented here is able to produce the sufficient applied current and thus viscoelastic force is desirably produced. The effectiveness of the developed isolator was evaluated numerically by MATLAB simulation and experimentally in comparison with the performances of a passive system and a system with on-off type semiactive controller. The results showed that the developed controller was successful in overcoming the disadvantages of conventional on-off semiactive control.

  7. Semi-decentralized Strategies in Structural Vibration Control

    Directory of Open Access Journals (Sweden)

    F. Palacios-Quiñonero


    Full Text Available In this work, the main ideas involved in the design of overlapping and multi-overlapping controllers via the Inclusion Principle are discussed and illustrated in the context of the Structural Vibration Control of tall buildings under seismic excitation. A detailed theoretical background on the Inclusion Principle and the design of overlapping controllers is provided. Overlapping and multi-overlapping LQR controllers are designed for a simplified five-story building model. Numerical simulations are conducted to asses the performance of the proposed semi-decentralized controllers with positive results.

  8. A review on the gun barrel vibrations and control for a main battle tank

    Directory of Open Access Journals (Sweden)

    Tolga Dursun


    Full Text Available Achieving high hitting accuracy for a main battle tank is challenging while the tank is on the move. This can be reached by proper design of a weapon control and gun system. In order to design an effective gun system while the tank is moving, better understanding of the dynamic behavior of the gun system is required. In this study, the dynamic behaviour of a gun system is discussed in this respect. Both experimental and numerical applications for the determination of the dynamic behaviour of a tank gun system are investigated. Methods such as the use of muzzle reference system (MRS and vibration absorbers, and active vibration control technology for the control and the reduction of the muzzle tip deflections are also reviewed. For the existing gun systems without making substantial modifications, MRS could be useful in controlling the deflections of gun barrels with estimation/prediction algorithms. The vibration levels could be cut into half by the use of optimised vibration absorbers for an existing gun. A new gun system with a longer barrel can be as accurate as the one with a short barrel with the appropriate structural modifications.

  9. Adaptive and robust active vibration control methodology and tests

    CERN Document Server

    Landau, Ioan Doré; Castellanos-Silva, Abraham; Constantinescu, Aurelian


    This book approaches the design of active vibration control systems from the perspective of today’s ideas of computer control. It formulates the various design problems encountered in the active management of vibration as control problems and searches for the most appropriate tools to solve them. The experimental validation of the solutions proposed on relevant tests benches is also addressed. To promote the widespread acceptance of these techniques, the presentation eliminates unnecessary theoretical developments (which can be found elsewhere) and focuses on algorithms and their use. The solutions proposed cannot be fully understood and creatively exploited without a clear understanding of the basic concepts and methods, so these are considered in depth. The focus is on enhancing motivations, algorithm presentation and experimental evaluation. MATLAB®routines, Simulink® diagrams and bench-test data are available for download and encourage easy assimilation of the experimental and exemplary material. Thre...

  10. T-S Fuzzy Control of Uncertain Chaotic Vibration

    Directory of Open Access Journals (Sweden)

    Abdelkrim Boukabou


    Full Text Available We present in this paper a novel and unified control approach that combines intelligent fuzzy logic methodology with predictive method for controlling chaotic vibration of a class of uncertain chaotic systems. We first introduce prediction into each subsystem of Takagi Sugeno (T-S fuzzy IF-THEN rules and then present a unified T-S predictive fuzzy model for chaos control. The proposed controller can successfully stabilize the chaos and track the desired targets. The simulation results illustrate its effectiveness.

  11. Active vibration control activities at the LaRC - Present and future (United States)

    Newsom, J. R.


    The NASA Controls-Structures-Interaction (CSI) program is presented with a description of the ground testing element objectives and approach. The goal of the CSI program is to develop and validate the technology required to design, verify and operate space systems in which the structure and the controls interact beneficially to meet the needs of future NASA missions. The operational Mini-Mast ground testbed and some sample active vibration control experimental results are discussed along with a description of the CSI Evolutionary Model testbed presently under development. Initial results indicate that embedded sensors and actuators are effective in controlling a large truss/reflector structure.

  12. Development of seismic technology and reliability based on vibration tests

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Youichi [Nuclear Power Engineering Corp., Tokyo (Japan)


    This paper deals with some of the vibration tests and investigations on the seismic safety of nuclear power plants (NPPs) in Japan. To ensure the reliability of the seismic safety of nuclear power plants, nuclear power plants in Japan have been designed according to the Technical Guidelines for Aseismic Design of Nuclear Power Plants. This guideline has been developed based on technical date base and findings which were obtained from many vibration tests and investigations. Besides the tests for the guideline, proving tests on seismic reliability of operating nuclear power plants equipment and systems have been carried out. In this paper some vibration tests and their evaluation results are presented. They have crucially contributed to develop the guideline. (J.P.N.)

  13. Vibration Performance Comparison Study on Current Fiber Optic Connector Technologies (United States)

    Ott, Melanie N.; Thomes Jr., William J.; LaRocca, Frank V.; Switzer, Robert C.; Chuska, Rick F.; Macmurphy, Shawn L.


    Fiber optic cables are increasingly being used in harsh environments where they are subjected to vibration. Understanding the degradation in performance under these conditions is essential for integration of the fibers into the given application. System constraints oftentimes require fiber optic connectors so subsystems can be removed or assembled as needed. In the present work, various types of fiber optic connectors were monitored in-situ during vibration testing to examine the transient change in optical transmission and the steady-state variation following the event. Inspection of the fiber endfaces and connectors was performed at chosen intervals throughout the testing.

  14. Fabrication of Biocompatible, Vibrational Magnetoelastic Materials for Controlling Cellular Adhesion

    Directory of Open Access Journals (Sweden)

    Rupak M. Rajachar


    Full Text Available This paper describes the functionalization of magnetoelastic (ME materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic field. However, since ME materials are not inherently biocompatible, surface modifications are needed for their implementation in biological settings. Here, the long-term stability of the ME material in an aqueous and biological environment is achieved by chemical-vapor deposition of a conformal Parylene-C layer, and further functionalized by methods of oxygen plasma etching and protein adsorption. In vitro cytotoxicity measurement and characterization of the vibrational behavior of the ME materials showed that Parylene-C coatings of 10 µm or greater could prevent hydrolytic degradation without sacrificing the vibrational behavior of the ME material. This work allows for long-term durability and functionality of ME materials in an aqueous and biological environment and makes the potential use of this technology in monitoring and modulating cellular behavior at the surface of implantable devices feasible.

  15. Development of Approaches to Creation of Active Vibration Control System in Problems of the Dynamics for Granular Media

    Directory of Open Access Journals (Sweden)

    Khomenko Andrei P.


    Full Text Available The article deals with the development of mathematical models and evaluation criteria of the vibration field in the dynamic interactions of the elements of the vibrational technological machines for the processes of vibrational strengthening of long-length parts with help of a steel balls working medium. The study forms a theoretical understanding of the modes of motions of material particles in interaction with a vibrating surface of the working body of the vibration machine. The generalized approach to the assessment of the dynamic quality of the work of vibrating machines in multiple modes of tossing, when the period of free flight of particles is a multiple of the period of the surface oscillations of the working body, is developed in the article. For the correction of vibration field of the working body, the characteristics of dynamic interactions of granular elements of the medium are taken into account using original sensors. The sensors that can detect different particularities of interaction of the granular medium elements at different points of the working body are proposed to evaluate the deviation from a homogeneous and one-dimensional mode of vibration field. Specially developed sensors are able to register interactions between a single granule, a system of granules in filamentous structures, and multipoint interactions of the elements in a close-spaced cylindrical structure. The system of regularization of the structure of vibration fields based on the introduction of motion translation devices is proposed using the multi-point sensor locations on the working body. The article refers to analytical approaches of the theory of vibration displacements. For the experimental data assessment, the methods of statistical analysis are applied. It is shown that the peculiar features of the motion of granular medium registered by the sensors can be used to build active control systems of field vibration.

  16. Active Vibration Control of a Monopile Offshore Structure

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Kirkegaard, Poul Henning; Thesbjerg, L.


    of the fluid velocity relative to the platform, and only this quantity need to be measured, which is easily performed by a flow meter fixed to the platform. The efficiency of the described closed loop control system has been verified by model tests in a wave flume in both regular and irregular wave conditions......In the Danish part of the North Sea monopile platforms with a cylindrical shaft have been used at the exploitation of marginal fields. In the paper a new principle for active vibration control of such structures is suggested. The principle is based on a control of the boundary layer flow around...

  17. [Actuator placement for active sound and vibration control (United States)


    Two refereed journal publications and ten talks given at conferences, seminars, and colloquia resulted from research supported by NASA. They are itemized in this report. The two publications were entitled "Reactive Tabu and Search Sensor Selection in Active Structural Acoustic Control Problems" and "Quelling Cabin Noise in Turboprop Aircraft via Active Control." The conference presentations covered various aspects of actuator placement, including location problems, for active sound and vibration control of cylinders, of commuter jets, of propeller driven or turboprop aircraft, and for quelling aircraft cabin or interior noise.

  18. Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar


    In rotor-blade systems basis as well as parametric vibration modes will appear due to the vibration coupling among flexible rotating blades and hub rigid body motion. Parametric vibration will typically occur when the hub operates at a constant angular velocity. Operating at constant velocity...... the model becomes periodic-variant. In order to reduce basis as well as parametric vibrations by means of active control in such systems a time-variant control strategy has to be adopted. This paper presents a methodology for designing an active controller to reduce vibrations in a coupled rotor......-blade system. The main aim is to control blade as well as hub vibrations in such a system by means of active control with focus on reducing the parametric vibration. A periodic state feedback controller is designed by transforming the system into a linear time-invariant form. Using this a controller...

  19. Composite multi-modal vibration control for a stiffened plate using non-collocated acceleration sensor and piezoelectric actuator (United States)

    Li, Shengquan; Li, Juan; Mo, Yueping; Zhao, Rong


    A novel active method for multi-mode vibration control of an all-clamped stiffened plate (ACSP) is proposed in this paper, using the extended-state-observer (ESO) approach based on non-collocated acceleration sensors and piezoelectric actuators. Considering the estimated capacity of ESO for system state variables, output superposition and control coupling of other modes, external excitation, and model uncertainties simultaneously, a composite control method, i.e., the ESO based vibration control scheme, is employed to ensure the lumped disturbances and uncertainty rejection of the closed-loop system. The phenomenon of phase hysteresis and time delay, caused by non-collocated sensor/actuator pairs, degrades the performance of the control system, even inducing instability. To solve this problem, a simple proportional differential (PD) controller and acceleration feed-forward with an output predictor design produce the control law for each vibration mode. The modal frequencies, phase hysteresis loops and phase lag values due to non-collocated placement of the acceleration sensor and piezoelectric patch actuator are experimentally obtained, and the phase lag is compensated by using the Smith Predictor technology. In order to improve the vibration control performance, the chaos optimization method based on logistic mapping is employed to auto-tune the parameters of the feedback channel. The experimental control system for the ACSP is tested using the dSPACE real-time simulation platform. Experimental results demonstrate that the proposed composite active control algorithm is an effective approach for suppressing multi-modal vibrations.

  20. Magnetic suspension motorized spindle-cutting system dynamics analysis and vibration control review

    Directory of Open Access Journals (Sweden)

    Xiaoli QIAO


    Full Text Available The performance of high-speed spindle directly determines the development of high-end machine tools. The cutting system's dynamic characteristics and vibration control effect are inseparable with the performance of the spindle,which influence each other, synergistic effect together the cutting efficiency, the surface quality of the workpiece and tool life in machining process. So, the review status on magnetic suspension motorized spindle, magnetic suspension bearing-flexible rotor system dynamics modeling theory and status of active control technology of flexible magnetic suspension motorized spindle rotor vibration are studied, and the problems which present in the magnetic suspension flexible motorized spindle rotor systems are refined, and the development trend of magnetic levitation motorized spindle and the application prospect is forecasted.

  1. Lattice Metamaterials with Mechanically Tunable Poisson's Ratio for Vibration Control (United States)

    Chen, Yanyu; Li, Tiantian; Scarpa, Fabrizio; Wang, Lifeng


    Metamaterials with artificially designed architectures are increasingly considered as new paradigmatic material systems with unusual physical properties. Here, we report a class of architected lattice metamaterials with mechanically tunable negative Poisson's ratios and vibration-mitigation capability. The proposed lattice metamaterials are built by replacing regular straight beams with sinusoidally shaped ones, which are highly stretchable under uniaxial tension. Our experimental and numerical results indicate that the proposed lattices exhibit extreme Poisson's-ratio variations between -0.7 and 0.5 over large tensile deformations up to 50%. This large variation of Poisson's-ratio values is attributed to the deformation pattern switching from bending to stretching within the sinusoidally shaped beams. The interplay between the multiscale (ligament and cell) architecture and wave propagation also enables remarkable broadband vibration-mitigation capability of the lattice metamaterials, which can be dynamically tuned by an external mechanical stimulus. The material design strategy provides insights into the development of classes of architected metamaterials with potential applications including energy absorption, tunable acoustics, vibration control, responsive devices, soft robotics, and stretchable electronics.

  2. Adaptive Vibration Control System for MR Damper Faults

    Directory of Open Access Journals (Sweden)

    Juan C. Tudón-Martínez


    Full Text Available Several methods have been proposed to estimate the force of a semiactive damper, particularly of a magnetorheological damper because of its importance in automotive and civil engineering. Usually, all models have been proposed assuming experimental data in nominal operating conditions and some of them are estimated for control purposes. Because dampers are prone to fail, fault estimation is useful to design adaptive vibration controllers to accommodate the malfunction in the suspension system. This paper deals with the diagnosis and estimation of faults in an automotive magnetorheological damper. A robust LPV observer is proposed to estimate the lack of force caused by a damper leakage in a vehicle corner. Once the faulty damper is isolated in the vehicle and the fault is estimated, an Adaptive Vibration Control System is proposed to reduce the fault effect using compensation forces from the remaining healthy dampers. To fulfill the semiactive damper constraints in the fault adaptation, an LPV controller is designed for vehicle comfort and road holding. Simulation results show that the fault observer has good performance with robustness to noise and road disturbances and the proposed AVCS improves the comfort up to 24% with respect to a controlled suspension without fault tolerance features.

  3. Vibrating membrane filtration as improved technology for microalgae dewatering


    Torras, C.; Salvadó, J.; Clavero, E.; C. Nurra


    10.1016/j.biortech.2014.01.115 The effect of shear-enhanced filtration by vibratory process in microalgae dewatering is presented in this paper. The aim of this research was to investigate the technical performance and improvement of vibrating membrane filtration compared with conventional tangential cross-flow filtration in microalgae concentration. An industrial-scale available commercial set-up was used. Several membrane materials as polyethersulfone, polyacrylonitrile, etc., and mean ...

  4. Active vibration control for piezoelectricity cantilever beam: an adaptive feedforward control method (United States)

    Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di


    This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.

  5. An adaptive vibration control method to suppress the vibration of the maglev train caused by track irregularities (United States)

    Zhou, Danfeng; Yu, Peichang; Wang, Lianchun; Li, Jie


    The levitation gap of the urban maglev train is around 8 mm, which puts a rather high requirement on the smoothness of the track. In practice, it is found that the track irregularity may cause stability problems when the maglev train is traveling. In this paper, the dynamic response of the levitation module, which is the basic levitation structure of the urban maglev train, is investigated in the presence of track irregularities. Analyses show that due to the structural configuration of the levitation module, the vibration of the levitation gap may be amplified and "resonances" may be observed under some specified track wavelengths and train speeds; besides, it is found that the gap vibration of the rear levitation unit in a levitation module is more significant than that of the front levitation unit, which agrees well with practice. To suppress the vibration of the rear levitation gap, an adaptive vibration control method is proposed, which utilizes the information of the front levitation unit as a reference. A pair of mirror FIR (finite impulse response) filters are designed and tuned by an adaptive mechanism, and they produce a compensation signal for the rear levitation controller to cancel the disturbance brought by the track irregularity. Simulations under some typical track conditions, including the sinusoidal track profile, random track irregularity, as well as track steps, indicate that the adaptive vibration control scheme can significantly reduce the amplitude of the rear gap vibration, which provides a method to improve the stability and ride comfort of the maglev train.

  6. Jerk Minimization Method for Vibration Control in Buildings (United States)

    Abatan, Ayo O.; Yao, Leummim


    In many vibration minimization control problems for high rise buildings subject to strong earthquake loads, the emphasis has been on a combination of minimizing the displacement, the velocity and the acceleration of the motion of the building. In most cases, the accelerations that are involved are not necessarily large but the change in them (jerk) are abrupt. These changes in magnitude or direction are responsible for most building damage and also create discomfort like motion sickness for inhabitants of these structures because of the element of surprise. We propose a method of minimizing also the jerk which is the sudden change in acceleration or the derivative of the acceleration using classical linear quadratic optimal controls. This was done through the introduction of a quadratic performance index involving the cost due to the jerk; a special change of variable; and using the jerk as a control variable. The values of the optimal control are obtained using the Riccati equation.

  7. Vibration control of a flexible structure with electromagnetic actuators

    DEFF Research Database (Denmark)

    Gruzman, Maurício; Santos, Ilmar


    This work presents the model of a shear-frame-type structure composed of six flexible beams and three rigid masses. Fixed on the ground, outside the structure, two voltage-controlled electromagnetic actuators are used for vibration control. To model the flexible beams, unidimensional finite...... elements were used. Nonlinear equations for the actuator electromagnetic force, noise in the position sensor, time delays for the control signal update and voltage saturation were also considered in the model. For controlling purposes, a discrete linear quadratic regulator combined with a predictive full......-order discrete linear observer was employed. Results of numerical simulations, where the structure is submitted to an impulsive disturbance force and to a harmonic force, show that the oscillations can be significantly reduced with the use of the electromagnetic actuators....

  8. Robust control of novel pendulum-type vibration isolation system (United States)

    Tsai, Meng-Shiun; Sun, Yann-Shuoh; Liu, Chun-Hsieh


    A novel pendulum-type vibration isolation system is proposed consisting of three active cables with embedded piezoelectric actuators and a passive elastomer layer. The dynamic response of the isolation module in the vertical and horizontal directions is modeled using the Lagrangian approach. The validity of the dynamic model is confirmed by comparing the simulation results for the frequency response in the vertical and horizontal directions with the experimental results. An approximate model is proposed to take into account system uncertainties such as payload changes and hysteresis effects. A robust quantitative feedback theory (QFT)-based active controller is then designed to ensure that the active control can achieve a high level of disturbance rejection in the low-frequency range even under variable loading conditions. It is shown that the controller achieves average disturbance rejection of -14 dB in the 2-60 Hz bandwidth range and -35 dB at the resonance frequency. The experimental results confirm that the proposed system achieves a robust vibration isolation performance under the payload in the range of 40-60 kg.


    Directory of Open Access Journals (Sweden)

    Asan Gani


    Full Text Available Active vibration control of the first three modes of a vibrating cantilever beam using collocated piezoelectric sensor and actuator is examined in this paper. To achieve this, a model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded piezoelectric patches that act as sensor, actuator and exciter respectively. A compensated inverse PID controller has been designed and developed to damp first three modes of vibration. Controllers have been designed for each mode and these are later combined in parallel to damp any of the three modes. Individual controller gives better reduction in sensor output for the second and third modes while the combined controller performs better for the first mode. Simulation studies are carried out using MATLAB. These results are compared and verified experimentally and the real-time implementation is carried out with xPC-target toolbox in MATLAB

  10. Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

    NARCIS (Netherlands)

    Berkhoff, Arthur P.; Wesselink, J.M.


    Model errors in multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. In this paper, a combination of high-authority control(HAC)and low-authority control (LAC)is considered for improved

  11. Active Vibration Control of a Monopile Offshore Structure

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Kirkegaard, Poul Henning; Thesbjerg, L.


    coefficient should be obtained in order to have a relatively small excitation on the cylinder. The drag coefficient can be controlled if the separation points of the boundary layers can be controlled. It is proposed to control the separation points by blowing compressed air out of the holes in the cylinder....... If the natura1 separation points of the boundary layers are rejected by blowing air out of the holes the drag coefficient will increase while it will decrease if it is possible to attach the boundary layer. The results from the experimental test have shown that it is possible to increase the drag coefficient...... with a factor 1.5-2 by blowing air out of the holes in a cylinder vibrating in a stationary water flow....

  12. Passive vibration control: a structure-immittance approach (United States)

    Zhang, Sara Ying; Jiang, Jason Zheng; Neild, Simon A.


    Linear passive vibration absorbers, such as tuned mass dampers, often contain springs, dampers and masses, although recently there has been a growing trend to employ or supplement the mass elements with inerters. When considering possible configurations with these elements broadly, two approaches are normally used: one structure-based and one immittance-based. Both approaches have their advantages and disadvantages. In this paper, a new approach is proposed: the structure-immittance approach. Using this approach, a full set of possible series-parallel networks with predetermined numbers of each element type can be represented by structural immittances, obtained via a proposed general formulation process. Using the structural immittances, both the ability to investigate a class of absorber possibilities together (advantage of the immittance-based approach), and the ability to control the complexity, topology and element values in resulting absorber configurations (advantages of the structure-based approach) are provided at the same time. The advantages of the proposed approach are demonstrated through two case studies on building vibration suppression and automotive suspension design, respectively.

  13. Lead-Lag Control for Helicopter Vibration and Noise Reduction (United States)

    Gandhi, Farhan


    As a helicopter transitions from hover to forward flight, the main rotor blades experience an asymmetry in flow field around the azimuth, with the blade section tangential velocities increasing on the advancing side and decreasing on the retreating side. To compensate for the reduced dynamic pressure on the retreating side, the blade pitch angles over this part of the rotor disk are increased. Eventually, a high enough forward speed is attained to produce compressibility effects on the advancing side of the rotor disk and stall on the retreating side. The onset of these two phenomena drastically increases the rotor vibratory loads and power requirements, thereby effectively establishing a limit on the maximum achievable forward speed. The alleviation of compressibility and stall (and the associated decrease in vibratory loads and power) would potentially result in an increased maximum forward speed. In the past, several methods have been examined and implemented to reduce the vibratory hub loads. Some of these methods are aimed specifically at alleviating vibration at very high flight speeds and increasing the maximum flight speed, while others focus on vibration reduction within the conventional flight envelope. Among the later are several types passive as well as active schemes. Passive schemes include a variety of vibration absorbers such as mechanical springs, pendulums, and bifilar absorbers. These mechanism are easy to design and maintain, but incur significant weight and drag penalties. Among the popular active control schemes in consideration are Higher Harmonic Control (HHC) and Individual Blade Control (IBC). HHC uses a conventional swash plate to generate a multi-cyclic pitch input to the blade. This requires actuators capable of sufficiently high power and bandwidth, increasing the cost and weight of the aircraft. IBC places actuators in the rotating reference frame, requiring the use of slip rings capable of transferring enough power to the actuators

  14. Control of noise and structural vibration a MATLAB-based approach

    CERN Document Server

    Mao, Qibo


    Control of Noise and Structural Vibration presents a MATLAB®-based approach to solving the problems of undesirable noise generation and transmission by structures and of undesirable vibration within structures in response to environmental or operational forces. The fundamentals of acoustics, vibration and coupling between vibrating structures and the sound fields they generate are introduced including a discussion of the finite element method for vibration analysis. Following this, the treatment of sound and vibration control begins, illustrated by example systems such as beams, plates and double plate structures. Sensor and actuator placement is explained as is the idea of modal sensor–actuators. The design of appropriate feedback systems includes consideration of basic stability criteria and robust active structural acoustic control. Single and multi-mode positive position feedback (PPF) control systems are also described in the context of loudspeaker–duct model with non-collocated loudspeaker–microp...

  15. Effect of vibration on muscle strength imbalance in lower extremity using multi-control whole body vibration platform. (United States)

    Yu, Chang Ho; Seo, Shin Bae; Kang, Seung Rok; Kim, Kyung; Kwon, Tae Kyu


    This study shows the improvement of muscle activity and muscle strength imbalance in the lower extremities through independent exercise loads in vibration platform. Twenty females of age 20 participated in this study. The subjects were divided into WBV group, with more than 10% of muscle strength imbalance between left and right the lower extremities, and control group, with less than 10% of muscle strength imbalance between left and right the lower extremities. As the prior experiment showed, different exercise postures provide different muscular activities. As a result, the highest muscular activity was found to be in the low squat posture. Therefore, the LS posture was selected for the exercise in this experiment. Vibration intensities were applied to dominant muscle and non-dominant muscle, and the vibration frequency was fixed at 25Hz for the WBV group. The control group was asked to perform the same exercise as the WBV group, without stimulated vibration. This exercise was conducted for a total of 4 weeks. As a result, the WBV group which showed an average deviation of 16% before the experiment, tended to decrease approximately to 5%. In this study, vibration exercise using load deviation is shown to be effective in improving the muscle strength imbalance.

  16. Low-frequency vibration control of floating slab tracks using dynamic vibration absorbers (United States)

    Zhu, Shengyang; Yang, Jizhong; Yan, Hua; Zhang, Longqing; Cai, Chengbiao


    This study aims to effectively and robustly suppress the low-frequency vibrations of floating slab tracks (FSTs) using dynamic vibration absorbers (DVAs). First, the optimal locations where the DVAs are attached are determined by modal analysis with a finite element model of the FST. Further, by identifying the equivalent mass of the concerned modes, the optimal stiffness and damping coefficient of each DVA are obtained to minimise the resonant vibration amplitudes based on fixed-point theory. Finally, a three-dimensional coupled dynamic model of a metro vehicle and the FST with the DVAs is developed based on the nonlinear Hertzian contact theory and the modified Kalker linear creep theory. The track irregularities are included and generated by means of a time-frequency transformation technique. The effect of the DVAs on the vibration absorption of the FST subjected to the vehicle dynamic loads is evaluated with the help of the insertion loss in one-third octave frequency bands. The sensitivities of the mass ratio of DVAs and the damping ratio of steel-springs under the floating slab are discussed as well, which provided engineers with the DVA's adjustable room for vibration mitigation. The numerical results show that the proposed DVAs could effectively suppress low-frequency vibrations of the FST when tuned correctly and attached properly. The insertion loss due to the attachment of DVAs increases as the mass ratio increases, whereas it decreases with the increase in the damping ratio of steel-springs.

  17. Vibration reduction for vision systems on board unmanned aerial vehicles using a neuro-fuzzy controller


    Marichal, N.; Tomas-Rodriguez, M.; Hernandez, A.; Castillo, S; Campoy, P.


    In this paper, an intelligent control approach based on neuro-fuzzy systems performance is presented, with the objective of counteracting the vibrations that affect the low-cost vision platform onboard an unmanned aerial system of rotating nature. A scaled dynamical model of a helicopter is used to simulate vibrations on its fuselage. The impact of these vibrations on the low-cost vision system will be assessed and an intelligent control approach will be derived in order to reduce its detrime...

  18. A new fuzzy sliding mode controller for vibration control systems using integrated-structure smart dampers (United States)

    Dzung Nguyen, Sy; Kim, Wanho; Park, Jhinha; Choi, Seung-Bok


    Vibration control systems using smart dampers (SmDs) such as magnetorheological and electrorheological dampers (MRD and ERD), which are classified as the integrated structure-SmD control systems (ISSmDCSs), have been actively researched and widely used. This work proposes a new controller for a class of ISSmDCSs in which high accuracy of SmD models as well as increment of control ability to deal with uncertainty and time delay are to be expected. In order to achieve this goal, two formualtion steps are required; a non-parametric SmD model based on an adaptive neuro-fuzzy inference system (ANFIS) and a novel fuzzy sliding mode controller (FSMC) which can weaken the model error of the ISSmDCSs and hence provide enhanced vibration control performances. As for the formulation of the proposed controller, first, an ANFIS controller is desgned to identify SmDs using the improved control algorithm named improved establishing neuro-fuzzy system (establishing neuro-fuzzy system). Second, a new control law for the FSMC is designed via Lyapunov stability analysis. An application to a semi-active MRD vehicle suspension system is then undertaken to illustrate and evaluate the effectiveness of the proposed control method. It is demonstrated through an experimental realization that the FSMC proposed in this work shows superior vibration control performance of the vehicle suspension compared to other surveyed controller which have similar structures to the FSMC, such as fuzzy logic and sliding mode control.

  19. Position and vibration control of flexible space robots (United States)

    Lim, Seungchul

    This dissertation is concerned with the position and vibration control of flexible articulated space robots consisting of a rigid platform, two flexible arms, and a rigid end-effector carrying a payload, all components being serially connected through revolute joints. The mission is to carry a payload over a prescribed trajectory in the inertial space, while suppressing the elastic vibration of the arms and the rigid-body perturbations. The equations of motion governing the robot dynamics are derived by means of Lagrangian mechanics and they include actuator dynamics. Based on the assumption that the elastic deformations and the rigid-body perturbations are small relative to the nominal trajectory-following rigid-body motions, a perturbation approach is adopted to separate the equations into nonlinear rigid-body equations and linear perturbation equations. The nominal trajectory is planned to conserve the limited actuator resources and keep the platform attitude stationary, by eliminating the inherent kinematic redundancy of the manipulator. By assuming perfect sensing, i.e., all the states are completely accessible, two kinds of controls are designed in discrete time. First, a feedforward control is designed to minimize the persistent disturbance resulting from the nominal motions. Next, a feedback control is synthesized based on the Linear Quadratic Regulator (LQR) theory with a prescribed degree of stability to make the system stable and further enhance the disturbance-rejection performances. These controls are subsequently applied to the case in which only the sensor outputs are available, and they are noisy. A finite number of sensors is assumed. A Kalman filter is designed to estimate the state on the assumption of zero-mean Gaussian white plant and measurement noise. In the real situation, controls are applied to the original plant rather than the linearized model, so that the Linear Quadratic Gaussian (LQG) control combined with robustness recovery methods

  20. Active vibration control using state space LQG and internal model control methods

    DEFF Research Database (Denmark)

    Mørkholt, Jakob; Elliott, S.J.


    Two ways of designing discrete time robust H2-controllers for feedback broadband active vibration control are compared through computer simulations. The methods are based on different models of disturbance and plant transfer functions, but yield controllers with identical properties. Two simple...... ways of introducing robustness into the H2-design are compared, and finally an efficient way of designing a practical IIR-controller is proposed....

  1. Vibrations control of light rail transportation vehicle via PID type fuzzy controller using parameters adaptive method


    METİN, Muzaffer; GÜÇLÜ, Rahmi


    In this study, a conventional PID type fuzzy controller and parameter adaptive fuzzy controller are designed to control vibrations actively of a light rail transport vehicle which modeled as 6 degree-of-freedom system and compared performances of these two controllers. Rail vehicle model consists of a passenger seat and its suspension system, vehicle body, bogie, primary and secondary suspensions and wheels. The similarity between mathematical model and real system is shown by compar...

  2. Research on signal demodulation technology of Mach-Zehnder optical fiber sensor vibration system (United States)

    Liu, Juncheng; Cheng, Pengshen; Hu, Tong


    Mach-Zehnder (M-Z) interferometer is frequently used in optical fiber vibration system. And signal demodulation technology plays an important role in the signal processing of M-Z optical fiber vibration system. In order to accurately get the phase information of the vibration signals, the signal demodulation technique based on M-Z interference principle is studied. In this paper, by analyzing the principles of 3 × 3 fiber coupler homodyne demodulation method and phase-generating carrier (PGC) technology, the advantages and disadvantages of the two demodulation methods for different vibration signal are presented. Then the method of judging signal strength is proposed. The correlation between the demodulation effects and strength of the perturbation signals is analyzed. Finally, the simulation experiments are carried out to compare the demodulation effects of the two demodulation methods, the results demonstrate that PGC demodulation technology has great advantages in weak signals, and the 3 × 3 fiber coupler is more suitable for strong signals.

  3. Reliability-based optimization of an active vibration controller using evolutionary algorithms (United States)

    Saraygord Afshari, Sajad; Pourtakdoust, Seid H.


    Many modern industrialized systems such as aircrafts, rotating turbines, satellite booms, etc. cannot perform their desired tasks accurately if their uninhibited structural vibrations are not controlled properly. Structural health monitoring and online reliability calculations are emerging new means to handle system imposed uncertainties. As stochastic forcing are unavoidable, in most engineering systems, it is often needed to take them into the account for the control design process. In this research, smart material technology is utilized for structural health monitoring and control in order to keep the system in a reliable performance range. In this regard, a reliability-based cost function is assigned for both controller gain optimization as well as sensor placement. The proposed scheme is implemented and verified for a wing section. Comparison of results for the frequency responses is considered to show potential applicability of the presented technique.

  4. A Randomized Controlled Trial of Whole Body Vibration Exposure on Markers of Bone Turnover in Postmenopausal Women (United States)

    Turner, Sarah; Torode, Margaret; Climstein, Mike; Naughton, Geraldine; Greene, David; Baker, Michael K.; Fiatarone Singh, Maria A.


    Purpose. To examine the effects of two doses of low-frequency (12 Hz), low-magnitude (0.3 g), whole body vibration on markers of bone formation and resorption in postmenopausal women. Methods. Women were recruited and randomized into a sham vibration control group, one time per week vibration group (1×/week), or three times per week vibration group (3×/week). Vibration exposure consisted of 20 minutes of intermittent vibration for the 1×/week and 3×/week groups, and sham vibration (vibration group but not in the 1×/wk vibration group compared with sham control (P vibration 3×/week for eight weeks in postmenopausal women results in a significant reduction in NTx/Cr, a marker of bone resorption, when compared with sham vibration exposure. PMID:21772975

  5. Adaptive PI control strategy for flat permanent magnet linear synchronous motor vibration suppression (United States)

    Meng, Fanwei; Liu, Chengying; Li, Zhijun; Wang, Liping


    Due to low damping ratio, flat permanent magnet linear synchronous motor's vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of K p and T i on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor's motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature

  6. Vibration control using a variable coil-based friction damper (United States)

    Amjadian, Mohsen; Agrawal, Anil K.


    This paper is focused on the analytical model, design, and simulation of a variable coil-based friction damper (VCBFD) for vibration control of structures. The proposed VCBFD is composed of a soft ferromagnetic plate, made of a linear magnetic material, and two identical thick rectangular air-core coils connected in parallel, each one attached to the plate through a friction pad. The friction force is provided by a normal force produced through an attractive electromagnetic interaction between the air-core coils (ACs) and the soft ferromagnetic plate when sliding relative to each other. The magnitude of the normal force in the damper is varied by a semi-active controller that controls the command current passing through the ACs. To demonstrate the efficiency of the proposed VCBFD and its semi-active controller, it has been implemented on a two-degree-of-freedom (2DOF) base-isolated model subjected to the acceleration components of three records of strong earthquakes. The results show that the performance of the proposed VCBFD in its passive-on mode is overshadowed by the undesirable effects of stick-slip motion. However, the damper in its semi-active mode is more successful in not only reducing the displacement of the base-floor but also avoiding stick-slip motion, due to acting completely in its sliding phase.

  7. Active vibration and noise control of vibro-acoustic system by using PID controller (United States)

    Li, Yunlong; Wang, Xiaojun; Huang, Ren; Qiu, Zhiping


    Active control simulation of the acoustic and vibration response of a vibro-acoustic cavity of an airplane based on a PID controller is presented. A full numerical vibro-acoustic model is developed by using an Eulerian model, which is a coupled model based on the finite element formulation. The reduced order model, which is used to design the closed-loop control system, is obtained by the combination of modal expansion and variable substitution. Some physical experiments are made to validate and update the full-order and the reduced-order numerical models. Optimization of the actuator placement is employed in order to get an effective closed-loop control system. For the controller design, an iterative method is used to determine the optimal parameters of the PID controller. The process is illustrated by the design of an active noise and vibration control system for a cavity structure. The numerical and experimental results show that a PID-based active control system can effectively suppress the noise inside the cavity using a sound pressure signal as the controller input. It is also possible to control the noise by suppressing the vibration of the structure using the structural displacement signal as the controller input. For an airplane cavity structure, considering the issue of space-saving, the latter is more suitable.

  8. Active Control of Panel Vibrations Induced by a Boundary Layer Flow (United States)

    Chow, Pao-Liu


    In recent years, active and passive control of sound and vibration in aeroelastic structures have received a great deal of attention due to many potential applications to aerospace and other industries. There exists a great deal of research work done in this area. Recent advances in the control of sound and vibration can be found in the several conference proceedings. In this report we will summarize our research findings supported by the NASA grant NAG-1-1175. The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to study the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. The vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings will be presented in the next three sections. In Section II we shall describe our results on the boundary control of nonlinear panel vibration, with or without flow excitation. Section III is concerned with active control of the vibration and sound radiation from a nonlinear elastic panel. A detailed description of our work on the parametric vibrational control of nonlinear elastic panel will be presented in Section IV. This paper will be submitted to the Journal

  9. Control concepts for an active vibration isolation system

    NARCIS (Netherlands)

    Kerber, F.; Hurlebaus, S.; Beadle, B. M.; Stobener, U.


    In the fields of high-resolution metrology and manufacturing, effective anti-vibration measures are required to obtain precise and repeatable results. This is particularly true when the amplitudes of ambient vibration and the dimensions of the investigated or manufactured structure are comparable,

  10. Active structural elements within a general vibration control framework

    NARCIS (Netherlands)

    Holterman, J.; de Vries, Theodorus J.A.; Isermann, R.


    High-precision machines typically suffer from small but annoying vibrations. As the most appropriate solution to a particular vibration problem is not always obvious, it may be convenient to cast the problem in a more general framework. This framework may then be used for frequency response

  11. Control of Rotor-Blade Coupled Vibrations Using Shaft-Based Actuation

    DEFF Research Database (Denmark)

    Christensen, Rene H.; Santos, Ilmar


    When implementing active control into bladed rotating machines aiming at reducing blade vibrations, it can be shown that blade as well as rotor vibrations can in fact be controlled by the use of only shaft-based actuation. Thus the blades have to be deliberately mistuned. This paper investigates...... of modal controllability and observability converge toward steady levels as the degree of mistuning is increased. Finally, experimental control results are presented to prove the theoretical conclusions and to show the feasibility of controlling rotor and blade vibrations by means of shaft-based actuation...

  12. Piezoelectric actuators in the active vibration control system of journal bearings (United States)

    Tůma, J.; Šimek, J.; Mahdal, M.; Pawlenka, M.; Wagnerova, R.


    The advantage of journal hydrodynamic bearings is high radial load capacity and operation at high speeds. The disadvantage is the excitation of vibrations, called an oil whirl, after crossing a certain threshold of the rotational speed. The mentioned vibrations can be suppressed using the system of the active vibration control with piezoactuators which move the bearing bushing. The motion of the bearing bushing is controlled by a feedback controller, which responds to the change in position of the bearing journal which is sensed by a pair of capacitive sensors. Two stacked linear piezoactuators are used to actuate the position of the bearing journal. This new bearing enables not only to damp vibrations but also serves to maintain the desired bearing journal position with an accuracy of micrometers. The paper will focus on the effect of active vibration control on the performance characteristics of the journal bearing.

  13. Advances in structural vibration control application of magneto-rheological visco-elastomer

    Directory of Open Access Journals (Sweden)

    Zuguang Ying


    Full Text Available Magneto-rheological visco-elastomer (MRVE as a new smart material developed in recent years has several significant advantages over magneto-rheological liquid. The adjustability of structural dynamics to random environmental excitations is required in vibration control. MRVE can supply considerably adjustable damping and stiffness for structures, and the adjustment of dynamic properties is achieved only by applied magnetic fields with changeless structure design. Increasing researches on MRVE dynamic properties, modeling, and vibration control application are presented. Recent advances in MRVE dynamic properties and structural vibration control application including composite structural vibration mitigation under uniform magnetic fields, vibration response characteristics improvement through harmonic parameter distribution, and optimal bounded parametric control design based on the dynamical programming principle are reviewed. Relevant main methods and results introduced are beneficial to understanding and researches on MRVE application and development.

  14. Active automotive engine vibration isolation using feedback control (United States)

    Olsson, Claes


    Large frequency band feedback active automotive engine vibration isolation is considered. A MIMO (multi-input multi-output) controller design for an active engine suspension system has been performed making use of a virtual development environment for design, analysis, and co-simulation based closed-loop verification. Utilising relevant control object dynamic modelling, this design strategy provides a powerful opportunity to deal with various plant dynamics, such as structural flexibility and nonlinear characteristics where the main objective is to approach the actual physical characteristics for design and verification in early design phases where no prototypes are yet physically available. H2 loop shaping technique proves to be powerful when achieving the desired frequency dependent loop gain while ensuring closed-loop stability. However, to achieve closed-loop stability two kinds of nonlinearities have to be taken into account. Those are nonlinear material characteristics of the engine mounts and large angular engine displacements. It is demonstrated how the adopted design strategy facilitates the investigation of the latter nonlinearity's impact on closed-loop characteristics. To deal with the nonlinearities, gain scheduling has been used.

  15. Active vibration control of a single-stage spur gearbox (United States)

    Dogruer, C. U.; Pirsoltan, Abbas K.


    The dynamic transmission error between driving and driven gears of a gear mechanism with torsional mode is induced by periodic time-varying mesh stiffness. In this study, to minimize the adverse effect of this time-varying mesh stiffness, a nonlinear controller which adjusts the torque acting on the driving gear is proposed. The basic approach is to modulate the input torque such that it compensates the periodic change in mesh stiffness. It is assumed that gears are assembled with high precision and gearbox is analyzed by a finite element software to calculate the mesh stiffness curve. Thus, change in the mesh stiffness, which is inherently nonlinear, can be predicted and canceled by a feed-forward loop. Then, remaining linear dynamics is controlled by pole placement techniques. Under these premises, it is claimed that any acceleration and velocity profile of the input shaft can be tracked accurately. Thereby, dynamic transmission error is kept to a minimum possible value and a spur gearbox, which does not emit much noise and vibration, is designed.

  16. Vibration control of rotor-bearing system by controlled squeeze-film damper bearings (United States)

    He, Erming; Gu, Jialiu


    A new vibration control scheme for rotor-bearing systems is presented which offers many advantages over the scheme proposed by Gu (1990). Due to the nonlinear state feedback, closed-loop control becomes possible. Thus control can be readily adjusted in accordance with transient state information. Optimal structure parameters are determined by the optimal control law. The control force is applied on line; by merely adjusting CSFDB structure parameters, control forces can be applied to the system. The feasibility of the present design is confirmed by simulation, which is performed for a flexible Jeffcott rotor elastically supported at both ends on identical CSFDBs.

  17. Vibration Control of Buildings Using Magnetorheological Damper: A New Control Algorithm

    Directory of Open Access Journals (Sweden)

    Aly Mousaad Aly


    Full Text Available This paper presents vibration control of a building model under earthquake loads. A magnetorheological (MR damper is placed in the building between the first floor and ground for seismic response reduction. A new control algorithm to command the MR damper is proposed. The approach is inspired by a quasi-bang-bang controller; however, the proposed technique gives weights to control commands in a fashion that is similar to a fuzzy logic controller. Several control algorithms including decentralized bang-bang controller, Lyapunov controller, modulated homogeneous friction controller, maximum energy dissipation controller, and clipped-optimal controller are used for comparison. The new controller achieved the best reduction in maximum interstory drifts and maximum absolute accelerations over all the control algorithms presented. This reveals that the proposed controller with the MR damper is promising and may provide the best protection to the building and its contents.

  18. The Comparative Study of Vibration Control of Flexible Structure Using Smart Materials

    Directory of Open Access Journals (Sweden)

    Juntao Fei


    Full Text Available Considerable attention has been devoted to active vibration control using intelligent materials as PZT actuators. This paper presents results on active control schemes for vibration suppression of flexible steel cantilever beam with bonded piezoelectric actuators. The PZT patches are surface bonded near the fixed end of flexible steel cantilever beam. The dynamic model of the flexible steel cantilever beam is derived. Active vibration control methods: optimal PID control, strain rate feedback control (SRF, and positive position feedback control (PPF are investigated and implemented using xPC Target real-time system. Experimental results demonstrate that the SRF and PPF controls have better performance in suppressing the vibration of cantilever steel beam than the optimal PID control.

  19. Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy (United States)

    Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping


    It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

  20. Active Vibration Control of the Smart Plate Using Artificial Neural Network Controller

    Directory of Open Access Journals (Sweden)



    Full Text Available The active vibration control (AVC of a rectangular plate with single input and single output approach is investigated using artificial neural network. The cantilever plate of finite length, breadth, and thickness having piezoelectric patches as sensors/actuators fixed at the upper and lower surface of the metal plate is considered for examination. The finite element model of the cantilever plate is utilized to formulate the whole strategy. The compact RIO and MATLAB simulation software are exercised to get the appropriate results. The cantilever plate is subjected to impulse input and uniform white noise disturbance. The neural network is trained offline and tuned with LQR controller. The various training algorithms to tune the neural network are exercised. The best efficient algorithm is finally considered to tune the neural network controller designed for active vibration control of the smart plate.

  1. Introduction of quartz vibrating beam accelerometer technology providing capability for low cost, fully digital navigation (United States)

    Holdren, F. V.; Norling, B. L.

    The proprietary 'Accelerex' vibrating-beam accelerometer is based on a specialized dual-tine quartz crystal resonator whose vibrating beam crystal employs two slender beams in a double-ended tuning fork-resembling geometry. This configuration furnishes perfect resonator dynamic balance, thereby obviating coupling and energy loss to the connecting structure. The slender beams of the crystal change frequency as a function of force in a way resembling the strings of a musical instrument. The Tactical Grade Accelerex system is optimized for low-cost tactical navigation and flight-control applications.

  2. Incorporating a disturbance observer with direct velocity feedback for control of human-induced vibrations (United States)

    Nyawako, Donald; Reynolds, Paul; Hudson, Emma


    Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.

  3. Emerging Engine Control Technologies

    DEFF Research Database (Denmark)

    Hendricks, Elbert; Chevalier, Alain


    In earlier work published by the author and co-authors, a dynamic model called a Mean Value Engine Model (MVEM) was developed. This model is physically based and is intended mainly for control applications. It is especially well suited to embedded model applications in engine controllers, susch...... as nonlinear observer based air/fuel ratio and advanced idle speed control. After a brief review of this model, it will be compared with other similar models which can be found in the literature. The attempt will be made to point out the differences between the new modified MVEM and those developed elsewhere...

  4. Active Vibration Control of a Railway Vehicle Carbody Using Piezoelectric Elements (United States)

    Molatefi, Habibollah; Ayoubi, Pejman; Mozafari, Hozhabr


    In recent years and according to modern transportation development, rail vehicles are manufactured lighter to achieve higher speed and lower transportation costs. On the other hand, weight reduction of rail vehicles leads to increase the structural vibration. In this study, Active Vibration Control of a rail vehicle using piezoelectric elements is investigated. The optimal control employed as the control approach regard to the first two modes of vibration. A simplified Car body structure is modeled in Matlab using the finite element theory by considering six DOF beam element and then the Eigen functions and mode shapes are derived. The surface roughness of different classes of rail tracks have been obtained using random vibration theory and applied to the secondary suspension as the excitation of the structure; Then piezoelectric mounted where the greatest moments were captured. The effectiveness of Piezoelectric in structural vibrations attenuation of car body is demonstrated through the state space equations and its effect on modal coefficient.

  5. Vibration Control of Novel Passive Multi-joints Rotational Friction Dampers

    DEFF Research Database (Denmark)

    Mualla, Imad H.; Koss, Holger


    This work presents a novel passive friction damper for vibration control of structures. The device is designed to dissipate input energy and protect buildings, especially large and tall buildings from structural and non-structural damage during moderate and severe vibration caused by earthquakes...

  6. Active Lubrication for Reducing Wear and Vibration: A combination of Fluid Power Control and Tribology

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar


    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through ori...

  7. Analysis and control of the vibration of doubly fed wind turbine (United States)

    Yu, Manye; Lin, Ying


    The fault phenomena of the violent vibration of certain doubly-fed wind turbine were researched comprehensively, and the dynamic characteristics, load and fault conditions of the system were discussed. Firstly, the structural dynamics analysis of wind turbine is made, and the dynamics mold is built. Secondly, the vibration testing of wind turbine is done with the German test and analysis systems BBM. Thirdly, signal should be analyzed and dealt with. Based on the experiment, spectrum analysis of the motor dynamic balance can be made by using signal processing toolbox of MATLAB software, and the analysis conclusions show that the vibration of wind turbine is caused by dynamic imbalance. The results show that integrating mechanical system dynamics theory with advanced test technology can solve the vibration problem more successfully, which is important in vibration diagnosis of mechanical equipment.

  8. Balanced calibration of resonant shunt circuits for piezoelectric vibration control

    DEFF Research Database (Denmark)

    Høgsberg, Jan; Krenk, Steen


    Shunting of piezoelectric transducers and suitable electric circuits constitutes an effective passive approach to resonant vibration damping of structures. Most common design concepts for resonant resistor-inductor (RL) shunt circuits rely on either maximization of the attainable modal damping...

  9. Damping of Torsional Beam Vibrations by Control of Warping Displacement

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Hoffmeyer, David; Ejlersen, Christian


    Supplemental damping of torsional beam vibrations is considered by viscous bimoments acting on the axial warping displacement at the beam supports. The concept is illustrated by solving the governing eigenvalue problem for various support configurations with the applied bimoments represented...

  10. Effect of Vibration on Pain Response to Heel Lance: A Pilot Randomized Control Trial. (United States)

    McGinnis, Kate; Murray, Eileen; Cherven, Brooke; McCracken, Courtney; Travers, Curtis


    Applied mechanical vibration in pediatric and adult populations has been shown to be an effective analgesic for acute and chronic pain, including needle pain. Studies among the neonatal population are lacking. According to the Gate Control Theory, it is expected that applied mechanical vibration will have a summative effect with standard nonpharmacologic pain control strategies, reducing behavioral and physiologic pain responses to heel lancing. To determine the safety and efficacy of mechanical vibration for relief of heel lance pain among neonates. In this parallel design randomized controlled trial, eligible enrolled term or term-corrected neonates (n = 56) in a level IV neonatal intensive care unit were randomized to receive either sucrose and swaddling or sucrose, swaddling, and vibration for heel lance analgesia. Vibration was applied using a handheld battery-powered vibrator (Norco MiniVibrator, Hz = 92) to the lateral aspect of the lower leg along the sural dermatome throughout the heel lance procedure. Neonatal Pain, Agitation, and Sedation Scale (N-PASS) scores, heart rate, and oxygen saturations were collected at defined intervals surrounding heel lancing. Infants in the vibration group (n = 30) had significantly lower N-PASS scores and more stable heart rates during heel stick (P = .006, P = .037) and 2 minutes after heel lance (P = .002, P = .016) than those in the nonvibration group. There were no adverse behavioral or physiologic responses to applied vibration in the sample. Applied mechanical vibration is a safe and effective method for managing heel lance pain. This pilot study suggests that mechanical vibration warrants further exploration as a nonpharmacologic pain management tool among the neonatal population.

  11. Reduction of the radiating sound of a submerged finite cylindrical shell structure by active vibration control. (United States)

    Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok


    In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  12. Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Seung-Bok Choi


    Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  13. Fiber optic vibration sensor for high-power electric machines realized using 3D printing technology (United States)

    Igrec, Bojan; Bosiljevac, Marko; Sipus, Zvonimir; Babic, Dubravko; Rudan, Smiljko


    The objective of this work was to demonstrate a lightweight and inexpensive fiber-optic vibration sensor, built using 3D printing technology, for high-power electric machines and similar applications. The working principle is based on modulating the light intensity using a blade attached to a bendable membrane. The sensor prototype was manufactured using PolyJet Matrix technology with DM 8515 Grey 35 Polymer. The sensor shows linear response, expected bandwidth (< 150 Hz), and from our measurements we estimated the damping ratio for used polymer to be ζ ≍ 0.019. The developed prototype is simple to assemble, adjust, calibrate and repair.

  14. Vibration Control of a Semiactive Vehicle Suspension System Based on Extended State Observer Techniques

    Directory of Open Access Journals (Sweden)

    Ze Zhang


    Full Text Available A feedback control method based on an extended state observer (ESO method is implemented to vibration reduction in a typical semiactive suspension (SAS system using a magnetorheological (MR damper as actuator. By considering the dynamic equations of the SAS system and the MR damper model, an active disturbance rejection control (ADRC is designed based on the ESO. Numerical simulation and real-time experiments are carried out with similar vibration disturbances. Both the simulation and experimental results illustrate the effectiveness of the proposed controller in vibration suppression for a SAS system.

  15. Vibration reduction on a nonlinear flexible structure through resonant control and disturbance estimator (United States)

    Cazzulani, Gabriele; Resta, Ferruccio; Ripamonti, Francesco


    Large mechanical structures are often affected by high level vibrations due to their flexibility. These vibrations can reduce the system performances and lifetime and the use of active vibration control strategies becomes very attractive. In this paper a combination of resonant control and a disturbance estimator is proposed. This solution is able to improve the system performances during the transient motion and also to reject the disturbance forces acting on the system. Both control logics are based on a modal approach, since it allows to describe the structure dynamics considering only few degrees of freedom.

  16. Active vibrations and noise control for turboprop application research program activities (United States)

    Paonessa, A.; Concilio, A.; Lecce, Leonardo V.


    The objectives of this work include the following: (1) development of active noise control techniques to alleviate inefficiencies and drawbacks of passive noise control approach especially at low frequencies; (2) reduction of structurally radiated noise applying external forces to the vibrating structure by means of force actuators made of piezoelectric material; and (3) reduction of fuselage vibration levels in propeller driven aircraft by means of distributed piezoelectric actuators that are actively controlled.

  17. Active Vibration Control of Plate Partly Treated with ACLD Using Hybrid Control

    Directory of Open Access Journals (Sweden)

    Dongdong Zhang


    Full Text Available A finite element model of plate partly treated with ACLD treatments is developed based on the constitutive equations of elastic, piezoelectric, viscoelastic materials and Hamilton’s principle. The Golla-Hughes-Mctavish (GHM method is employed to describe the frequency-dependent characteristics of viscoelastic material (VEM. A model reduction is completed by using iterative dynamic condensation and balance model reduction method to design an effective control system. The emphasis is concerned on hybrid (combined feedback/feedforward control system to attenuate the vibration of plates with ACLD treatments. The optimal linear quadratic Gaussian (LQG controller is considered as a feedback channel and the adaptive filtered-reference LMS (FxLMS controller is used as a feedforward channel. They can be utilized individually or in a hybrid way to suppress the vibration of plate/ACLD system. The results show that the hybrid controller which combines feedback/feedforward together can reduce the displacement amplitude of plate/ACLD system subjected to a complicated disturbance substantially without requiring more control effort. Furthermore, the hybrid controller has more rapid and stable convergence rate than the adaptive feedforward FxLMS controller. Meanwhile, perfect robustness to phase error of the cancellation path in feedforward controller and the weight matrices in feedback LQG controller is demonstrated in proposed hybrid controller. Therefore, its application in structural engineering can be highly appreciated.

  18. Hybrid Vibration Control under Broadband Excitation and Variable Temperature Using Viscoelastic Neutralizer and Adaptive Feedforward Approach

    Directory of Open Access Journals (Sweden)

    João C. O. Marra


    Full Text Available Vibratory phenomena have always surrounded human life. The need for more knowledge and domain of such phenomena increases more and more, especially in the modern society where the human-machine integration becomes closer day after day. In that context, this work deals with the development and practical implementation of a hybrid (passive-active/adaptive vibration control system over a metallic beam excited by a broadband signal and under variable temperature, between 5 and 35°C. Since temperature variations affect directly and considerably the performance of the passive control system, composed of a viscoelastic dynamic vibration neutralizer (also called a viscoelastic dynamic vibration absorber, the associative strategy of using an active-adaptive vibration control system (based on a feedforward approach with the use of the FXLMS algorithm working together with the passive one has shown to be a good option to compensate the neutralizer loss of performance and generally maintain the extended overall level of vibration control. As an additional gain, the association of both vibration control systems (passive and active-adaptive has improved the attenuation of vibration levels. Some key steps matured over years of research on this experimental setup are presented in this paper.

  19. A new compound control method for sine-on-random mixed vibration test (United States)

    Zhang, Buyun; Wang, Ruochen; Zeng, Falin


    Vibration environmental test (VET) is one of the important and effective methods to provide supports for the strength design, reliability and durability test of mechanical products. A new separation control strategy was proposed to apply in multiple-input multiple-output (MIMO) sine on random (SOR) mixed mode vibration test, which is the advanced and intensive test type of VET. As the key problem of the strategy, correlation integral method was applied to separate the mixed signals which included random and sinusoidal components. The feedback control formula of MIMO linear random vibration system was systematically deduced in frequency domain, and Jacobi control algorithm was proposed in view of the elements, such as self-spectrum, coherence, and phase of power spectral density (PSD) matrix. Based on the excessive correction of excitation in sine vibration test, compression factor was introduced to reduce the excitation correction, avoiding the destruction to vibration table or other devices. The two methods were synthesized to be applied in MIMO SOR vibration test system. In the final, verification test system with the vibration of a cantilever beam as the control object was established to verify the reliability and effectiveness of the methods proposed in the paper. The test results show that the exceeding values can be controlled in the tolerance range of references accurately, and the method can supply theory and application supports for mechanical engineering.

  20. A fractional-order controller for vibration suppression of uncertain structures. (United States)

    Aghababa, Mohammad Pourmahmood


    The problem of active control of vibration structures has attracted much attention over the past decades. A general description of the control problem of vibration systems is to design an active controller to suppress the vibrations of the system induced by external disturbances such as an earthquake. In this paper, a novel fractional-order sliding mode control is introduced to attenuate the vibrations of structures with uncertainties and disturbances. After establishing a stable fractional sliding surface, a sliding mode control law is proposed. Then, the global asymptotic stability of the closed-loop system is analytically proved using fractional Lyapunov stability theorem. Finally, the robustness and applicability of the technique are verified using two examples, including a three degree of freedom structure and a two-story shear building. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Effect of nonlinearity of connecting dampers on vibration control of connected building structures

    Directory of Open Access Journals (Sweden)

    Masatoshi eKasagi


    Full Text Available The connection of two building structures with dampers is one of effective vibration control systems. In this vibration control system, both buildings have to possess different vibration properties in order to provide a higher vibration reduction performance. In addition to such condition of different vibration properties of both buildings, the connecting dampers also play an important role in the vibration control mechanism. In this paper, the effect of nonlinearity of connecting dampers on the vibration control of connected building structures is investigated in detail. A high-damping rubber damper and an oil damper with and without relief mechanism are treated. It is shown that, while the high-damping rubber damper is effective in a rather small deformation level, the linear oil damper is effective in a relatively large deformation level. It is further shown that, while the oil dampers reduce the response in the same phase as the case without dampers, the high-damping rubber dampers change the phase. The merit is that the high-damping rubber can reduce the damper deformation and keep the sufficient space between both buildings. This can mitigate the risk of building pounding.

  2. Self-Tuning Vibration Control of a Rotational Flexible Timoshenko Arm Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Minoru Sasaki


    Full Text Available A self-tuning vibration control of a rotational flexible arm using neural networks is presented. To the self-tuning control system, the control scheme consists of gain tuning neural networks and a variable-gain feedback controller. The neural networks are trained so as to make the root moment zero. In the process, the neural networks learn the optimal gain of the feedback controller. The feedback controller is designed based on Lyapunov's direct method. The feedback control of the vibration of the flexible system is derived by considering the time rate of change of the total energy of the system. This approach has the advantage over the conventional methods in the respect that it allows one to deal directly with the system's partial differential equations without resorting to approximations. Numerical and experimental results for the vibration control of a rotational flexible arm are discussed. It verifies that the proposed control system is effective at controlling flexible dynamical systems.

  3. Optimal Placement of Piezoelectric Plates to Control Multimode Vibrations of a Beam

    Directory of Open Access Journals (Sweden)

    Fabio Botta


    Full Text Available Damping of vibrations is often required to improve both the performance and the integrity of engineering structures, for example, gas turbine blades. In this paper, we explore the possibility of using piezoelectric plates to control the multimode vibrations of a cantilever beam. To develop an effective control strategy and optimize the placement of the active piezoelectric elements in terms of vibrations amplitude reduction, a procedure has been developed and a new analytical solution has been proposed. The results obtained have been corroborated by comparison with the results from a multiphysics finite elements package (COMSOL, results available in the literature, and experimental investigations carried out by the authors.

  4. Piezoelectric Tailoring with Enhanced Electromechanical Coupling for Concurrent Vibration Control of Mistuned Periodic Structures

    National Research Council Canada - National Science Library

    Wang, Kon-Well


    The objective of this research is to advance the state of the art of vibration control of mistuned periodic structures utilizing the electromechanical coupling and damping characteristics of piezoelectric networking...

  5. Methodology for Analysing Controllability and Observability of Bladed Disc Coupled Vibrations

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar


    and observability of bladed discs. The aim is to determine where to locate actuators and sensors in order to be capable of controlling and monitoring both disc lateral and blade vibrations. The analysis methodology is based on the time-variant modal analysis. A numerical example of the methodogy is provided....... A tuned rotating bladed disc is analysed. The analysis shows that blade actuators and sensors are inevitable in order to control and monitor the vibrations. Moreover, it shows that the controllability and observability depends very strongly on the rotational speed.......Many bladed rotating machines such as helicopters, turbines and compressors are susceptible to blade faults due to vibration problems. Typically, blade vibrations in this kind of machines are suppressed by using passive mechanical components. However, when passive control techniques...

  6. Vibration Reduction Methods and Techniques for Rotorcraft Utilizing On-Blade Active Control Project (United States)

    National Aeronautics and Space Administration — Rotor blades adapted for vibration control have the added benefit of extended blade and rotor life, as well as improved passenger comfort. Approaches that have been...

  7. Spherical tuned liquid damper for vibration control in wind turbines

    DEFF Research Database (Denmark)

    Chen, Jun-Ling; Georgakis, Christos T.


    A tuned liquid damper (TLD), which consisted of two-layer hemispherical containers, partially filled with water, was investigated as a cost-effective method to reduce the wind-induced vibration of wind turbines. A 1/20 scaled test model was designed to investigate its performance on the shaking...... table. Three groups of equivalent ground accelerations were inputted to simulate the wind-induced dynamic response under different load cases. The influence of rotors and nacelle was assumed to be a concentrated tip mass. A series of free and forced vibration experiments were performed on the shaking...

  8. Control of Chaos in Rate-Dependent Friction-Induced Vibration Using Adaptive Sliding Mode Control and Impulse Damper

    Directory of Open Access Journals (Sweden)

    Ehsan Maani Miandoab


    Full Text Available Two different control methods, namely, adaptive sliding mode control and impulse damper, are used to control the chaotic vibration of a block on a belt system due to the rate-dependent friction. In the first method, using the sliding mode control technique and based on the Lyapunov stability theory, a sliding surface is determined, and an adaptive control law is established which stabilizes the chaotic response of the system. In the second control method, the vibration of this system is controlled by an impulse damper. In this method, an impulsive force is applied to the system by expanding and contracting the PZT stack according to efficient control law. Numerical simulations demonstrate the effectiveness of both methods in controlling the chaotic vibration of the system. It is shown that the settling time of the controlled system using impulse damper is less than that one controlled by adaptive sliding mode control; however, it needs more control effort.

  9. Feed-forward control of gear mesh vibration using piezoelectric actuators (United States)

    Montague, Gerald T.; Kascak, Albert F.; Palazzolo, Alan; Manchala, Daniel; Thomas, Erwin


    This paper presents a novel means for suppressing gear mesh-related vibrations. The key components in this approach are piezoelectric actuators and a high-frequency, analog feed-forward controller. Test results are presented and show up to a 70-percent reduction in gear mesh acceleration and vibration control up to 4500 Hz. The principle of the approach is explained by an analysis of a harmonically excited, general linear vibratory system.

  10. Acute effect of whole body vibration on postural control in congenitally blind subjects: a preliminary evidence. (United States)

    di Cagno, Alessandra; Giombini, Arrigo; Iuliano, Enzo; Moffa, Stefano; Caliandro, Tiziana; Parisi, Attilio; Borrione, Paolo; Calcagno, Giuseppe; Fiorilli, Giovanni


    The purpose of this study was to investigate the acute effects of whole body vibration at optimal frequency, on postural control in blind subjects. Twenty-four participants, 12 congenital blind males (Experimental Group), and 12 non-disabled males with no visual impairment (Control Groups) were recruited. The area of the ellipse and the total distance of the center of pressure displacements, as postural control parameters, were evaluated at baseline (T0), immediately after the vibration (T1), after 10 min (T10) and after 20 min (T20). Whole body vibration protocol consisted into 5 sets of 1 min for each vibration, with 1 min rest between each set on a vibrating platform. The total distance of center of pressure showed a significant difference (p static balance were found after an acute bout of whole body vibration at optimal frequency in blind subjects and, consequently, whole body vibration may be considered as a safe application in individuals who are blind.

  11. Real-Time Performance of Mechatronic PZT Module Using Active Vibration Feedback Control. (United States)

    Aggogeri, Francesco; Borboni, Alberto; Merlo, Angelo; Pellegrini, Nicola; Ricatto, Raffaele


    This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment and adjust to alterations in the environment. In particular, an innovative smart actuator has been designed and developed to satisfy machining requirements during active vibration control. This study presents the mechatronic model based on the kinematic and dynamic analysis of the AVC device. To ensure a real time performance, a H2-LQG controller has been developed and validated by simulations involving a machine tool, PZT actuator and controller models. The Hardware in the Loop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests has been performed to validate the AVC module on a commercial machine tool. The feasibility of the real time vibration damping is demonstrated and the simulation accuracy is evaluated.

  12. Vibration control of an elastic strip by a singular force

    Indian Academy of Sciences (India)

    MS received 10 September 2008; revised 27 August 2009; accepted 17 December. 2009. Abstract. Vibration characteristics of an elastic plate in the shape of an infinite strip are changed by applying a lateral concentrated force to the plate. The homo- geneous, isotropic, elastic plate is infinite in the x-direction and the sides ...

  13. Vibration control of an elastic strip by a singular force

    Indian Academy of Sciences (India)

    Vibration characteristics of an elastic plate in the shape of an infinite strip are changed by applying a lateral concentrated force to the plate. The homogeneous, isotropic, elastic plate is infinite in the -direction and the sides are simply supported. The size of the force is changed in proportion to the displacement measured at ...

  14. Actuator Control of Edgewise Vibrations in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Staino, A.; Basu, B.; Nielsen, Søren R.K.


    Edgewise vibrations with low aerodynamic damping are of particular concern in modern multi-megawatt wind turbines, as large amplitude cyclic oscillations may significantly shorten the life-time of wind turbine components, and even lead to structural damages or failures. In this paper, a new blade ...

  15. Semiactive Vibration Control of a Wind Turbine Tower using an MR Damper

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Poulsen, B. L.


    For fatigue vibration reduction modern wind turbines are installed with different kind of passive systems such as a tuned mass damper or a tuned liquid damper. However, passive control systems are limited because they cannot adapt to broadbanded loading conditions, i.e. they perform well...... or semiactive system for reducing the fatigue will be more optimal than a passive control system. This paper presents a numerically and experimentally investigation of semiactive vibration control of wind turbine tower vibrations by using a magnetorheological (MR) fluid damper. Numerical simulations as well...... as experimental laboratory results indicate that the MR damper approach is superior to a traditional tuned mass damper for reducing the vibration of wind turbine towers....

  16. Adaptive inverse control for rotorcraft vibration reduction. Ph.D. Thesis (United States)

    Jacklin, S. A.


    The Least Mean Square (LMS) algorithm is extended to solve the multiple-input, multiple-output problem of alleviating N/Rev helicopter fuselage vibration by means of adaptive inverse control. A frequency domain locally linear model is used to represent the transfer matrix relating the high harmonic pitch control inputs to the harmonic vibration outputs to be controlled. By using the inverse matrix as the controller gain matrix, an adaptive inverse regulator is formed to alleviate the N/Rev vibration. The stability and rate of convergence properties of the extended LMS algorithm are discussed. It is shown that the stability ranges for the elements of the stability gain matrix are directly related to the eigenvalues of the vibration signal information matrix for the learning phase, but not for the control phase. The overall conclusion is that the LMS adaptive inverse control method can form a robust vibration control system, but will require some tuning of the input sensor gains, the stability gain matrix, and the amount of control relaxation to be used. The learning curve of the controller during the learning phase is shown to be quantitatively close to that predicted by averaging the learning curves of the normal modes. It is shown that the best selections of the stability gain matrix elements and the amount of control relaxation is basically a compromise between slow, stable convergence and fast convergence with increased possibility of unstable identification.

  17. Vibration Study of Fork-lift Truck Based on the Virtual Prototype Technology

    Directory of Open Access Journals (Sweden)

    YANG Mingliang


    Full Text Available The forklift truck is one of important equipments of the modern logistics system. As the forklift truck is running, the driver seat and steering wheel of a certain type of fork-lift truck vibrate strongly, virtual prototyping technology and multi-body dynamics are used to make simulation of dynamic performance of fork-lift truck in this paper, and then the test result is compared with time course load that obtained from frame junction with the annex. We should repeatedly modify the simulation model based on test results, which is consistent with the actual results. Based on this model, so we put forward measures for improving design: Firstly, the axis of rotation of oval steering axle is implied; Secondly, the overhead guard is connected with the frame by the rubber cushion blocks at four different locations; Thirdly, the engine is fixed on the frame by the rubber cushion blocks (shock mount in two different position. The improved simulation and experimental verification are carried out under the same conditions, and the results show that the fundamental frequency of seat of the improved fork-lift truck and vibration energy are lower. The result proves the practical value of this method in the research of the vibration characteristics of complete engineering machine.

  18. Control model for dampening hand vibrations using information of internal and external coordinates. (United States)

    Togo, Shunta; Kagawa, Takahiro; Uno, Yoji


    In the present study, we investigate a control mechanism that dampens hand vibrations. Here, we propose a control method with two components to suppress hand vibrations. The first is a passive suppression method that lowers the joint stiffness to passively dampen the hand vibrations. The second is an active suppression method that adjusts an equilibrium point based on skyhook control to actively dampen the hand vibrations. In a simulation experiment, we applied these two methods to dampen hand vibrations during the shoulder's horizontal oscillation. We also conducted a measurement experiment wherein a subject's shoulder was sinusoidally oscillated by a platform that generated horizontal oscillations. The results of the measurement experiments showed that the jerk of each part of the arm in a task using a cup filled with water was smaller than the shoulder jerk and that in a task with a cup filled with stones was larger than the shoulder jerk. Moreover, the amplitude of the hand trajectory in both horizontal and vertical directions was smaller in a task using a cup filled with water than in a task using a cup filled with stones. The results of the measurement experiments were accurately reproduced by the active suppression method based on skyhook control. These results suggest that humans dampen hand vibrations by controlling the equilibrium point through the information of the external workspace and the internal body state rather than by lowering joint stiffness only by using internal information.

  19. Control model for dampening hand vibrations using information of internal and external coordinates.

    Directory of Open Access Journals (Sweden)

    Shunta Togo

    Full Text Available In the present study, we investigate a control mechanism that dampens hand vibrations. Here, we propose a control method with two components to suppress hand vibrations. The first is a passive suppression method that lowers the joint stiffness to passively dampen the hand vibrations. The second is an active suppression method that adjusts an equilibrium point based on skyhook control to actively dampen the hand vibrations. In a simulation experiment, we applied these two methods to dampen hand vibrations during the shoulder's horizontal oscillation. We also conducted a measurement experiment wherein a subject's shoulder was sinusoidally oscillated by a platform that generated horizontal oscillations. The results of the measurement experiments showed that the jerk of each part of the arm in a task using a cup filled with water was smaller than the shoulder jerk and that in a task with a cup filled with stones was larger than the shoulder jerk. Moreover, the amplitude of the hand trajectory in both horizontal and vertical directions was smaller in a task using a cup filled with water than in a task using a cup filled with stones. The results of the measurement experiments were accurately reproduced by the active suppression method based on skyhook control. These results suggest that humans dampen hand vibrations by controlling the equilibrium point through the information of the external workspace and the internal body state rather than by lowering joint stiffness only by using internal information.

  20. Flight Control of Biomimetic Air Vehicles Using Vibrational Control and Averaging (United States)

    Tahmasian, Sevak; Woolsey, Craig A.


    A combination of vibrational inputs and state feedback is applied to control the flight of a biomimetic air vehicle. First, a control strategy is developed for longitudinal flight, using a quasi-steady aerodynamic model and neglecting wing inertial effects. Vertical and forward motion is controlled by modulating the wings' stroke and feather angles, respectively. Stabilizing control parameter values are determined using the time-averaged dynamic model. Simulations of a system resembling a hawkmoth show that the proposed controller can overcome modeling error associated with the wing inertia and small parameter uncertainties when following a prescribed trajectory. After introducing the approach through an application to longitudinal flight, the control strategy is extended to address flight in three-dimensional space.

  1. Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm


    -dependent response to the IR fields is due to the anharmonicity of the potential. A subsequent ultraviolet laser pulse in resonance at the outer turning point of the vibrational motion can then dissociate the oscillating molecules, all with the same orientation, leading to spatial control of the photofragment......Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...

  2. Feedback Controller Stabilizing Vibrations of a Flexible Cable Related to an Overhead Crane

    Directory of Open Access Journals (Sweden)

    Abdelhadi Elharfi


    Full Text Available The problem of stabilizing vibrations of flexible cable related to an overhead crane is considered. The cable vibrations are described by a hyperbolic partial differential equation (HPDE with an update boundary condition. We provide in this paper a systematic way to derive a boundary feedback law which restores in a closed form the cable vibrations to the desired zero equilibrium. Such a control law is explicitly constructed in terms of the solution of an appropriate kernel PDE. The pursued approach combines the “backstepping method” and “semigroup theory”.

  3. Active vibration control of ring-stiffened cylindrical shell structure using macro fiber composite actuators. (United States)

    Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok


    Vibration control performance of the ring-stiffened cylindrical shell structure is experimentally evaluated in this work. In order to achieve high control performance, advanced flexible piezoelectric actuator whose commercial name is Macro-Fiber Composite (MFC) is adapted to the shell structure. Governing equation is derived by finite element method and dynamic characteristics are investigated from the modal analysis results. Ring-stiffened cylindrical shell structure is then manufactured and modal test is conducted to verify modal analysis results. An optimal controller is designed and experimentally realized to the proposed shell structure system. Vibration control performance is experimentally evaluated in time domain and verified by simulated control results.

  4. Study on antilock brake system with elastic membrane vibration generated by controlled solenoid excitation (United States)

    Wibowo, Zakaria, Lambang, Lullus; Triyono, Muhayat, Nurul


    The most effective chassis control system for improving vehicle safety during severe braking is anti-lock braking system (ABS). Antilock effect can be gained by vibrate the pad brake at 7 to 20 cycle per second. The aim of this study is to design a new method of antilock braking system with membrane elastic vibrated by solenoid. The influence of the pressure fluctuations of brake fluid is investigated. Vibration data is collected using a small portable accelerometer-slam stick. The experiment results that the vibration of brake pad caused by controlled solenoid excitation at 10 Hz is obtained by our new method. The result of measurements can be altered by varying brake fluid pressure.

  5. Study on antilock brake system with elastic membrane vibration generated by controlled solenoid excitation

    Energy Technology Data Exchange (ETDEWEB)

    Wibowo,, E-mail:; Zakaria,, E-mail:; Lambang, Lullus, E-mail:; Triyono,, E-mail:; Muhayat, Nurul, E-mail: [Mechanical Engineering Department, Sebelas Maret University, Surakarta 57128 (Indonesia)


    The most effective chassis control system for improving vehicle safety during severe braking is anti-lock braking system (ABS). Antilock effect can be gained by vibrate the pad brake at 7 to 20 cycle per second. The aim of this study is to design a new method of antilock braking system with membrane elastic vibrated by solenoid. The influence of the pressure fluctuations of brake fluid is investigated. Vibration data is collected using a small portable accelerometer-slam stick. The experiment results that the vibration of brake pad caused by controlled solenoid excitation at 10 Hz is obtained by our new method. The result of measurements can be altered by varying brake fluid pressure.

  6. Vibration control of uncertain multiple launch rocket system using radial basis function neural network (United States)

    Li, Bo; Rui, Xiaoting


    Poor dispersion characteristics of rockets due to the vibration of Multiple Launch Rocket System (MLRS) have always restricted the MLRS development for several decades. Vibration control is a key technique to improve the dispersion characteristics of rockets. For a mechanical system such as MLRS, the major difficulty in designing an appropriate control strategy that can achieve the desired vibration control performance is to guarantee the robustness and stability of the control system under the occurrence of uncertainties and nonlinearities. To approach this problem, a computed torque controller integrated with a radial basis function neural network is proposed to achieve the high-precision vibration control for MLRS. In this paper, the vibration response of a computed torque controlled MLRS is described. The azimuth and elevation mechanisms of the MLRS are driven by permanent magnet synchronous motors and supposed to be rigid. First, the dynamic model of motor-mechanism coupling system is established using Lagrange method and field-oriented control theory. Then, in order to deal with the nonlinearities, a computed torque controller is designed to control the vibration of the MLRS when it is firing a salvo of rockets. Furthermore, to compensate for the lumped uncertainty due to parametric variations and un-modeled dynamics in the design of the computed torque controller, a radial basis function neural network estimator is developed to adapt the uncertainty based on Lyapunov stability theory. Finally, the simulated results demonstrate the effectiveness of the proposed control system and show that the proposed controller is robust with regard to the uncertainty.


    Directory of Open Access Journals (Sweden)

    Roberd Saragih


    Full Text Available This paper is concerned with the vibration and position control of a single link flexible manipulator. Robot link manipulators are widely used in various industrial applications. It is desirable to build light weight flexible manipulators. Light flexible manipulators have a variety of applications, most significantly in space exploration,manufacturing automation, construction, mining, and hazardous operation. Timoshenko beam theory is used to derive mathematical model of a flexible manipulator. The dynamic equations of motion are obtained using the Lagrange's formulation of dynamics.The H∞ controller is designed for vibration and position control of the system. Simulations are presented and show that vibration and position control of a single flexible link can be controlled with the designed H∞ controller.

  8. Comparative analysis and exprimental results of advanced control strategies for vibration suppression in aircraft wings (United States)

    Birs, Isabela R.; Folea, Silviu; Copot, Dana; Prodan, Ovidiu; Muresan, Cristina-I.


    The smart beam is widely used as a means of studying the dynamics and active vibration suppression possibilities in aircraft wings. The advantages obtained through this approach are numerous, among them being aircraft stability and manoeuvrability, turbulence immunity, passenger safety and reduced fatigue damage. The paper presents the tuning of two controllers: Linear Quadratic Regulator and Fractional Order Proportional Derivative controller. The active vibration control methods were tested on a smart beam, vibrations being mitigated through piezoelectric patches. The obtained experimental results are compared in terms of settling time and control effort, experimentally proving that both types of controllers can be successfully used to reduce oscillations. The analysis in this paper provides for a necessary premise regarding the tuning of a fractional order enhanced Linear Quadratic Regulator, by combining the advantages of both control strategies.

  9. Vibrationally mediated control of single-electron transmission in weakly coupled molecule-metal junctions

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob


    We propose a mechanism which allows one to control the transmission of single electrons through a molecular junction. The principle utilizes the emergence of transmission sidebands when molecular vibrational modes are coupled to the electronic state mediating the transmission. We will show that i....... As an example we perform a density-functional theory analysis of a benzene molecule between two Au(111) contacts and show that exciting a particular vibrational mode can give rise to transmission of a single electron....

  10. Closed-Loop Input Shaping Control of Vibration in Flexible Structures via Adaptive Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Ming-Chang Pai


    Full Text Available Input shaping technique is widely used in reducing or eliminating residual vibration of flexible structures. The exact elimination of the residual vibration via input shaping technique depends on the amplitudes and instants of impulse application. However, systems always have parameter uncertainties which can lead to performance degradation. In this paper, a closed-loop input shaping control scheme is developed for uncertain flexible structures. The algorithm is based on input shaping control and adaptive sliding mode control. The proposed scheme does not need a priori knowledge of upper bounds on the norm of the uncertainties, but estimates them by using the adaptation technique. This scheme guarantees closed-loop system stability, and yields good performance and robustness in the presence of parameter uncertainties and external disturbances as well. Furthermore, it is shown that increasing the robustness to parameter uncertainties does not lengthen the duration of the impulse sequence. Simulation results demonstrate the efficacy of the proposed closed-loop input shaping control scheme.

  11. IIR filtering based adaptive active vibration control methodology with online secondary path modeling using PZT actuators (United States)

    Boz, Utku; Basdogan, Ipek


    Structural vibrations is a major cause for noise problems, discomfort and mechanical failures in aerospace, automotive and marine systems, which are mainly composed of plate-like structures. In order to reduce structural vibrations on these structures, active vibration control (AVC) is an effective approach. Adaptive filtering methodologies are preferred in AVC due to their ability to adjust themselves for varying dynamics of the structure during the operation. The filtered-X LMS (FXLMS) algorithm is a simple adaptive filtering algorithm widely implemented in active control applications. Proper implementation of FXLMS requires availability of a reference signal to mimic the disturbance and model of the dynamics between the control actuator and the error sensor, namely the secondary path. However, the controller output could interfere with the reference signal and the secondary path dynamics may change during the operation. This interference problem can be resolved by using an infinite impulse response (IIR) filter which considers feedback of the one or more previous control signals to the controller output and the changing secondary path dynamics can be updated using an online modeling technique. In this paper, IIR filtering based filtered-U LMS (FULMS) controller is combined with online secondary path modeling algorithm to suppress the vibrations of a plate-like structure. The results are validated through numerical and experimental studies. The results show that the FULMS with online secondary path modeling approach has more vibration rejection capabilities with higher convergence rate than the FXLMS counterpart.

  12. Positioning and Microvibration Control by Electromagnets of an Air Spring Vibration Isolation System (United States)

    Watanabe, Katsuhide; Cui, Weimin; Haga, Takahide; Kanemitsu, Yoichi; Yano, Kenichi


    Active positioning and microvibration control has been attempted by electromagnets equipped in a bellows-type, air-spring vibration isolation system. Performance tests have been carried out to study the effects. The main components of the system's isolation table were four electromagnetic actuators and controllers. The vibration isolation table was also equipped with six acceleration sensors for detecting microvibration of the table. The electromagnetic actuators were equipped with bellows-type air springs for passive support of the weight of the item placed on the table, with electromagnets for active positioning, as well as for microvibration control, and relative displacement sensors. The controller constituted a relative feedback system for positioning control and an absolute feedback system for vibration isolation control. In the performance test, a 1,490 kg load (net weight of 1,820 kg) was placed on the vibration isolation table, and both the positioning and microvibration control were carried out electromagnetically. Test results revealed that the vibration transmission was reduced by 95%.

  13. Control of forced vibrations of mechanical structures by an electromagnetic controller with a permanent magnet

    DEFF Research Database (Denmark)

    Stein, George Juraj; Darula, Radoslav; Sorokin, Sergey


    A theoretical analysis of an electromagnetic vibration controller is presented. The analyzed device consists of a pot-type iron core with a coil and a permanent magnet as a source of constant magnetic flux. The magnetic circuit is closed by a yoke, excited by an external harmonic mechanical force....... The so generated magnetic flux variation induces alternating voltage in the electric circuit, which is dissipated in a shunt resistor. The induced current driven through the coil generates magnetic force, which damps the excitation force and changes the damped natural frequency of the oscillatory system...

  14. Adaptive vibration control using synchronous demodulation with machine tool controller motor commutation (United States)

    Hopkins, David James [Livermore, CA


    A control system and method for actively reducing vibration in a spindle housing caused by unbalance forces on a rotating spindle, by measuring the force-induced spindle-housing motion, determining control signals based on synchronous demodulation, and provide compensation for the measured displacement to cancel or otherwise reduce or attenuate the vibration. In particular, the synchronous demodulation technique is performed to recover a measured spindle housing displacement signal related only to the rotation of a machine tool spindle, and consequently rejects measured displacement not related to spindle motion or synchronous to a cycle of revolution. Furthermore, the controller actuates at least one voice-coil (VC) motor, to cancel the original force-induced motion, and adapts the magnitude of voice coil signal until this measured displacement signal is brought to a null. In order to adjust the signal to a null, it must have the correct phase relative to the spindle angle. The feedback phase signal is used to adjust a common (to both outputs) commutation offset register (offset relative to spindle encoder angle) to force the feedback phase signal output to a null. Once both of these feedback signals are null, the system is compensating properly for the spindle-induced motion.

  15. Avoiding the Health Hazard of People from Construction Vehicles: A Strategy for Controlling the Vibration of a Wheel Loader. (United States)

    Chi, Feng; Zhou, Jun; Zhang, Qi; Wang, Yong; Huang, Panling


    The vibration control of a construction vehicle must be carried out in order to meet the aims of sustainable environmental development and to avoid the potential human health hazards. In this paper, based on market feedback, the driver seat vibration of a type of wheel loader in the left and right direction, is found to be significant over a certain speed range. In order to find abnormal vibration components, the order tracking technique (OTT) and transmission path analysis (TPA) were used to analyze the vibration sources of the wheel loader. Through this analysis, it can be seen that the abnormal vibration comes from the interaction between the tire tread and the road, and this is because the vibration was amplified by the cab mount, which was eventually transmitted to the cab seat. Finally, the seat vibration amplitudes were decreased by up to 50.8%, after implementing the vibration reduction strategy.

  16. Identification for Active Vibration Control of Flexible Structure Based on Prony Algorithm

    Directory of Open Access Journals (Sweden)

    Xianjun Sheng


    Full Text Available Flexible structures have been widely used in many fields due to the advantages of light quality, small damping, and strong flexibility. However, flexible structures exhibit the vibration in the process of manipulation, which reduces the pointing precision of the system and causes fatigue of the machine. So, this paper focuses on the identification method for active vibration control of flexible structure. The modal parameters and transfer function of the system are identified from the step response signal based on Prony algorithm, while the vibration is attenuated by using the input shaping technique designed according to the parameters identified from the Prony algorithm. Eventually, the proposed approach is applied to the most common flexible structure, a piezoelectric cantilever beam actuated by Macro Fiber Composite (MFC. The experimental results demonstrate that the Prony algorithm is very effective and accurate on the dynamic modeling of flexible structure and input shaper could significantly reduce the vibration and improve the response speed of system.

  17. A concept for semi-active vibration control with a serial-stiffness-switch system (United States)

    Min, Chaoqing; Dahlmann, Martin; Sattel, Thomas


    This work deals with a new semi-active vibration control concept with a serial-stiffness-switch system (SSSS), which can be seen as one and a half degree-of-freedom system. The proposed switched system is mainly composed of two serial elements, each of which consists of one spring and one switch in parallel with each other. This mechanical structure benefits from a specified switching law based on the zero crossing of velocity in order to realize vibration reduction. In contrast with conventional ways, the new system is capable of harvesting vibration energy as potential energy stored in springs, and then applies it to vibration reduction. In this paper, the concept is characterized, simulated, evaluated, and proven to be able to improve the system response. The equivalent stiffness and natural frequency of the switched system are mathematically formulated and verified.

  18. Development of a Self-Powered Magnetorheological Damper System for Cable Vibration Control

    Directory of Open Access Journals (Sweden)

    Zhihao Wang


    Full Text Available A new self-powered magnetorheological (MR damper control system was developed to mitigate cable vibration. The power source of the MR damper is directly harvested from vibration energy through a rotary permanent magnet direct current (DC generator. The generator itself can also serve as an electromagnetic damper. The proposed smart passive system also incorporates a roller chain and sprocket, transforming the linear motion of the cable into the rotational motion of the DC generator. The vibration mitigation performance of the presented self-powered MR damper system was evaluated by model tests with a 21.6 m long cable. A series of free vibration tests of the cable with a passively operated MR damper with constant voltage, an electromagnetic damper alone, and a self-powered MR damper system were performed. Finally, the vibration control mechanisms of the self-powered MR damper system were investigated. The experimental results indicate that the supplemental modal damping ratios of the cable in the first four modes can be significantly enhanced by the self-powered MR damper system, demonstrating the feasibility and effectiveness of the new smart passive system. The results also show that both the self-powered MR damper and the generator are quite similar to a combination of a traditional linear viscous damper and a negative stiffness device, and the negative stiffness can enhance the mitigation efficiency against cable vibration.

  19. Semi-active on-off damping control of a dynamic vibration absorber using Coriolis force (United States)

    La, Viet Duc


    A passive dynamic vibration absorber (DVA) moving along a pendulum can cause the nonlinear Coriolis damping to reduce the pendulum swing. This paper proposes a simple semi-active on-off damping controller to improve the passive Coriolis DVA. The aim of the on-off damping control is to amplify the DVA resonance motion to increase the energy dissipated. Moreover, the paper finds the analytical solution of the harmonic vibration of semi-active controlled system. The accuracy of the analytical formulas and the superior performance of the semi-active DVA are verified by numerical simulations.

  20. Reduction of Structural Vibrations by Passive and Semiactively Controlled Friction Dampers

    Directory of Open Access Journals (Sweden)

    L. Gaul


    Full Text Available Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines, and increasing structure durability. Besides optimization of the mechanical design or various types of passive damping treatments, active structural vibration control concepts are efficient means to reduce unwanted vibrations. In this contribution, two different semiactive control concepts for vibration reduction are proposed that adapt to the normal force of attached friction dampers. Thereby, semiactive control concepts generally possess the advantage over active control in that the closed loop is intrinsically stable and that less energy is required for the actuation than in active control. In the chosen experimental implementation, a piezoelectric stack actuator is used to apply adjustable normal forces between a structure and an attached friction damper. Simulation and experimental results of a benchmark structure with passive and semiactively controlled friction dampers are compared for stationary narrowband excitation. For simulations of the control performance, transient simulations must be employed to predict the achieved vibration damping. It is well known that transient simulation of systems with friction and normal contact requires excessive computational power due to the nonlinear constitutive laws and the high contact stiffnesses involved. However, commercial finite-element codes do not allow simulating feedback control in a general way. As a remedy, a special simulation framework is developed which allows efficiently modeling interfaces with friction and normal contact by appropriate constitutive laws which are implemented by contact elements in a finite-element model. Furthermore, special model reduction techniques using a substructuring approach are employed for faster simulation.

  1. Active vibration control of Flexible Joint Manipulator using Input Shaping and Adaptive Parameter Auto Disturbance Rejection Controller (United States)

    Li, W. P.; Luo, B.; Huang, H.


    This paper presents a vibration control strategy for a two-link Flexible Joint Manipulator (FJM) with a Hexapod Active Manipulator (HAM). A dynamic model of the multi-body, rigid-flexible system composed of an FJM, a HAM and a spacecraft was built. A hybrid controller was proposed by combining the Input Shaping (IS) technique with an Adaptive-Parameter Auto Disturbance Rejection Controller (APADRC). The controller was used to suppress the vibration caused by external disturbances and input motions. Parameters of the APADRC were adaptively adjusted to ensure the characteristic of the closed loop system to be a given reference system, even if the configuration of the manipulator significantly changes during motion. Because precise parameters of the flexible manipulator are not required in the IS system, the operation of the controller was sufficiently robust to accommodate uncertainties in system parameters. Simulations results verified the effectiveness of the HAM scheme and controller in the vibration suppression of FJM during operation.

  2. High accuracy position adjustment and vibration isolation actuator with the controlled ferrofluid (United States)

    Wu, Shuai; Li, Chunfang; Zhao, Xiangyu; Jiao, Zongxia


    An actuator for microposition adjustment and vibration isolation using the controlled ferrofluid is reported in this letter. The proposed actuator levitates on the ferrofluid which is affected by the combined dynamic magnetic field which is formed by coupling a permanent magnetic field with a controlled electromagnetic field. A controlled electromagnetic field is superposed on the permanent magnetic field in order to change the shape of the ferrofluid to ultimately move the actuator. The experimental results indicate that the proposed actuator can adjust the position with high accuracy and has a good dynamic performance. The proposed actuator can bear over 2 N loads, and the positioning accuracy is within 0.1 μ m. The stroke of the actuator is about of ±30 μ m with no load, and the stroke increases to ±75 μ m at 2 N load. Its dynamic band with -3 dB amplitude attenuation and -90° phase is over 40 Hz. In addition, the displacement has a very good linear relationship with the input current. The results also demonstrate that the actuator can isolate vibration in a wide frequency range, as the low frequency vibration can be compensated by the active motion control, while the high frequency vibration can be attenuated by the elasticity and damping effects of the ferrofluid. Consequently, the proposed actuator has a significant potential for applications where the high accuracy micro-position adjustment and vibration isolation are needed.

  3. Semiactive Vibration Control Using a Magnetorheological Damper and a Magnetorheological Elastomer Based on the Bouc-Wen Model

    Directory of Open Access Journals (Sweden)

    Wei Zhu


    Full Text Available A vibration control system is put forward using a magnetorheological damper (MRD and a magnetorheological elastomer (MRE connected in series. In order to model the hysteresis of the MRD, a Bouc-Wen model and a corresponding parameter identification method are developed for the MRD. The experimental results validate the proposed Bouc-Wen model that can predict the hysteretic behavior of the MRD accurately. The role of the MRE is illustrated by an example of a single degree-of-freedom system. A semiactive vibration control strategy of the proposed vibration control system is proposed. To validate this new approach, experiments are conducted and the results highlight significantly improved vibration reduction effect of the proposed vibration control system than the vibration control system only using the MRD.

  4. Stochastic resonance whole body vibration reduces musculoskeletal pain: A randomized controlled trial. (United States)

    Elfering, Achim; Thomann, Jan; Schade, Volker; Radlinger, Lorenz


    To examined the effects of stochastic resonance whole-body vibration training on musculoskeletal pain in young healthy individuals. Participants were 43 undergraduate students of a Swiss University. The study was designed as a randomized controlled trial (RCT) with randomized group allocation. The RCT consisted of two groups each given 12 training sessions during four weeks with either 5 Hz- Training frequency (training condition) or 1.5 Hz Training frequency (control condition). Outcome was current musculoskeletal pain assessed in the evening on each day during the four week training period. Multilevel regression analysis showed musculoskeletal pain was significantly decreased in the training condition whereas there was no change in the control condition (B = -0.023, SE = 0.010, P = 0.021). Decrease in current musculoskeletal pain over four weeks was linear. Stochastic resonance whole-body vibration reduced musculoskeletal pain in young healthy individuals. Stochastic resonance vibration and not any other exercise component within training caused pain reduction.

  5. Tuned rolling-ball dampers for vibration control in wind turbines

    DEFF Research Database (Denmark)

    Chen, Junling; Georgakis, Christos T.


    With wind turbines growing in size and cost, it is necessary to reduce their dynamic responses and improve their fatigue lifetime. A passive tuned-mass damper (TMD) is a very efficient solution for vibration control in structures subjected to wind excitations. In this study, a tuned rolling......-ball damper characterized by single or multiple steel balls rolling in a spherical container is proposed to be mounted on the top of wind turbines to reduce the wind-induced vibration. A 1/20 scale shaking table model was developed to evaluate the control effectiveness of the damper. The wind-induced dynamic...... responses of the test model with and without TMD were obtained from the shaking table tests. The test results indicated that the rolling-ball dampers could effectively suppress the wind-induced vibration of wind turbines. The damper with three balls in one container had better control effectiveness than...

  6. Application of Time Delay Consideration on Bridge Vibration Control Method with Active Tendons

    Directory of Open Access Journals (Sweden)

    Lezin Seba MINSILI


    Full Text Available For many years bridge structures have been designed or constructed as passive structures that rely on their mass and solidity to resist external forces, while being incapable of adapting to the dynamics of an ever-changing environment. When the rigidity assumption is not met in particular for high-rise structures like bridge towers, a proper dynamic model should be established and conclusions made on the differential vibration of the tower when it is investigated out of the bridge system. The present work outlines a vibration control method by tendons on the tower of cable supported structures considering time delay effects, based on the discrete-time Linearization of the Feedback Gain Matrix. The efficiency of this vibration control method first proposed on the design process of a local bridge in Cameroon, is more compatible to the control of civil structures and is of great interest in accordance with simulation results.

  7. Resonant passive–active vibration absorber with integrated force feedback control

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Brodersen, Mark Laier; Krenk, Steen


    A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the d...

  8. A unified control strategy for the active reduction of sound and vibration

    NARCIS (Netherlands)

    Doelman, N.J.


    The generalized minimum variance (GMV) control strategy is proposed as an effective strategy for active sound and vibration control systems. The GMV strategy is shown to unify well-known adaptive filtering approaches based on LMS-type algorithms and purely feedback strategies as used in other types

  9. Stochastic resonance whole-body vibration improves postural control in health care professionals: a worksite randomized controlled trial. (United States)

    Elfering, Achim; Schade, Volker; Stoecklin, Lukas; Baur, Simone; Burger, Christian; Radlinger, Lorenz


    Slip, trip, and fall injuries are frequent among health care workers. Stochastic resonance whole-body vibration training was tested to improve postural control. Participants included 124 employees of a Swiss university hospital. The randomized controlled trial included an experimental group given 8 weeks of training and a control group with no intervention. In both groups, postural control was assessed as mediolateral sway on a force plate before and after the 8-week trial. Mediolateral sway was significantly decreased by stochastic resonance whole-body vibration training in the experimental group but not in the control group that received no training (p resonance whole-body vibration training is an option in the primary prevention of balance-related injury at work. Copyright 2014, SLACK Incorporated.

  10. Quantum control spectroscopy of vibrational modes: Comparison of control scenarios for ground and excited states in {beta}-carotene

    Energy Technology Data Exchange (ETDEWEB)

    Hauer, Juergen; Buckup, Tiago [Fachbereich Chemie, Physikalische Chemie, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse, D-35043 Marburg (Germany); Motzkus, Marcus [Fachbereich Chemie, Physikalische Chemie, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse, D-35043 Marburg (Germany)], E-mail:


    Quantum control spectroscopy (QCS) is used as a tool to study, address selectively and enhance vibrational wavepacket motion in large solvated molecules. By contrasting the application of Fourier-limited and phase-modulated excitation on different electronic states, the interplay between the controllability of vibrational coherence and electronic resonance is revealed. We contrast control on electronic ground and excited state by introducing an additional pump beam prior to a DFWM-sequence (Pump-DFWM). Via phase modulation of this initial pump pulse, coherent control is extended to structural evolution on the vibrationally hot ground state (hot-S{sub 0}) and lowest lying excited state (S{sub 1}) of {beta}-carotene. In an open loop setup, the control scenarios for these different electronic states are compared in their effectiveness and mechanism.

  11. Vibration effect and control of In-Wheel Switched Reluctance Motor for electric vehicle (United States)

    Sun, Wei; Li, Yinong; Huang, Jingying; Zhang, Nong


    The Switched Reluctance Motor (SRM) processes favorable driving capacity and great application potential in In-Wheel Motor (IWM) Electric Vehicle (EV). However vibration and noise problems are always the disadvantages of SRM. This paper investigates the vibration and noise issues and corresponding control methodology for the IWM application of SRM. By utilizing the analytical Fourier fitting method, a convenience method for modeling In-Wheel Switched Reluctance Motor (IW SRM) is proposed and the characteristics of the unbalanced residual lateral force related to vibration excitation are analyzed. Then the dynamic negative effect of IW SRM on vehicle is analyzed with a quarter driving and vibration vehicle model. It is found that the vertical shock occurs under the vehicle starting condition and high frequency force excitation exists under the constant speed condition. To address these issues, corresponding control methods are proposed, modified and compared. The proposed combined vibration feedback control of current chopping with PWM can effectively reduce the SRM residual force and ensure the required vehicle speed, though some slight low frequency forces are induced.

  12. Active vibration control testing of the SPICES program: final demonstration article (United States)

    Dunne, James P.; Jacobs, Jack H.


    The Synthesis and Processing of Intelligent Cost Effective Structures (SPICES) Program is a partnership program sponsored by the Advanced Research Projects Agency. The mission of the program is to develop cost effective material processing and synthesis technologies to enable new products employing active vibration suppression and control devices to be brought to market. The two year program came to fruition in 1995 through the fabrication of the final smart components and testing of an active plate combined with two trapezoidal rails, forming an active mount. Testing of the SPICES combined active mount took place at McDonnell Douglas facilities in St. Louis, MO, in October-December 1995. Approximately 15 dB reduction in overall response of a motor mounted on the active structure was achieved. Further details and results of the SPICES combined active mount demonstration testing are outlined. Results of numerous damping and control strategies that were developed and employed in the testing are presented, as well as aspects of the design and fabrication of the SPICES active mount components.

  13. Microencapsulation of a hydrophilic model molecule through vibration nozzle and emulsion phase inversion technologies. (United States)

    Dorati, Rossella; Genta, Ida; Modena, Tiziana; Conti, Bice


    The goal of the present work was to evaluate and discuss vibration nozzle microencapsulation (VNM) technology combined to lyophilization, for the microencapsulation of a hydrophilic model molecule into a hydrophilic polymer. Fluorescein-loaded alginate microparticles prepared by VNM and emulsion phase inversion microencapsulation (EPIM) were lyophilized. Morphology, particle size distribution, lyophilized microspheres stability upon rehydration, drug loading and in vitro release were evaluated. Well-formed microspheres were obtained by the VNM technique, with higher yields of production (93.3-100%) and smaller particle size (d50138.10-158.00) than the EPIM microspheres. Rehydration upon lyophilization occurred in 30 min maintaining microsphere physical integrity. Fluorescein release was always faster from the microspheres obtained by VNM (364 h) than from those obtained by EPIM (504 h). The results suggest that VNM is a simple, easy to be scaled-up process suitable for the microencapsulation hydrophilic drugs.

  14. Vibration reduction in helicopters using active control of structural response (ACSR) with improved aerodynamic modeling (United States)

    Cribbs, Richard Clay

    This dissertation describes the development of a coupled rotor/flexible fuselage aeroelastic response model including rotor/fuselage aerodynamic interactions. This model is used to investigate fuselage vibrations and their suppression using active control of structural response (ACSR). The fuselage, modeled by a three dimensional structural dynamic finite element model, is combined with a flexible, four-bladed, hingeless rotor. Each rotor blade is structurally modeled as an isotropic Euler-Bernoulli beam with coupled flap-lag-torsional dynamics assuming moderate deflections. A free wake model is incorporated into the aeroelastic response model and is validated against previous studies. Two and three dimensional sources model the fuselage aerodynamics. Direct aerodynamic influences of the rotor and wake on the fuselage are calculated by integrating pressures over the surface of the fuselage. The fuselage distorts the wake and influences the air velocities at the rotor which alters the aerodynamic loading. This produces fully coupled rotor/fuselage aerodynamic interactions. The influence of the aerodynamic refinements on vibrations is studied in detail. Results indicate that a free wake model and the inclusion of fuselage aerodynamic effects on the rotor and wake are necessary for vibration prediction at all forward speeds. The direct influence of rotor and wake aerodynamics on the fuselage plays a minor role in vibrations. Accelerations with the improved aerodynamic model are significantly greater than uniform inflow results. The influence of vertical separation between the rotor and fuselage on vibrations is also studied. An ACSR control algorithm is developed that preferentially reduces accelerations at selected airframe locations of importance. Vibration reduction studies are carried out using this improved control algorithm and a basic algorithm studied previously at UCLA. Both ACSR methods markedly reduce acceleration amplitudes with no impact on the rotor

  15. Wireless sensing and vibration control with increased redundancy and robustness design. (United States)

    Li, Peng; Li, Luyu; Song, Gangbing; Yu, Yan


    Control systems with long distance sensor and actuator wiring have the problem of high system cost and increased sensor noise. Wireless sensor network (WSN)-based control systems are an alternative solution involving lower setup and maintenance costs and reduced sensor noise. However, WSN-based control systems also encounter problems such as possible data loss, irregular sampling periods (due to the uncertainty of the wireless channel), and the possibility of sensor breakdown (due to the increased complexity of the overall control system). In this paper, a wireless microcontroller-based control system is designed and implemented to wirelessly perform vibration control. The wireless microcontroller-based system is quite different from regular control systems due to its limited speed and computational power. Hardware, software, and control algorithm design are described in detail to demonstrate this prototype. Model and system state compensation is used in the wireless control system to solve the problems of data loss and sensor breakdown. A positive position feedback controller is used as the control law for the task of active vibration suppression. Both wired and wireless controllers are implemented. The results show that the WSN-based control system can be successfully used to suppress the vibration and produces resilient results in the presence of sensor failure.

  16. Vibration Control of Double-Beam System with Multiple Smart Damping Members


    Dominik Pisarski; Tomasz Szmidt; Czesław I. Bajer; Bartłomiej Dyniewicz; Jacek M. Bajkowski


    A control method to stabilize vibration of a double cantilever system with a set of smart damping blocks is designed and numerically evaluated. The externally controlled magnetorheological sheared elastomer damping block is considered, but other smart materials can be used as well. The robust bang-bang control law for stabilization the bilinear system is elaborated. The key feature of the closed loop controller is the efficiency for different types of initial excitement. By employing the fini...

  17. Space Station Displays and Controls Technology Evolution (United States)

    Blackburn, Greg C.


    Viewgraphs on space station displays and controls technology evolution are presented. Topics covered include: a historical perspective; major development objectives; current development activities; key technology areas; and technology evolution issues.

  18. Control Application of Piezoelectric Materials to Aeroelastic Self-Excited Vibrations

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rashidifar


    Full Text Available A method for application of piezoelectric materials to aeroelasticity of turbomachinery blades is presented. The governing differential equations of an overhung beam are established. The induced voltage in attached piezoelectric sensors due to the strain of the beam is calculated. In aeroelastic self-excited vibrations, the aerodynamic generalized force of a specified mode can be described as a linear function of the generalized coordinate and its derivatives. This simplifies the closed loop system designed for vibration control of the corresponding structure. On the other hand, there is an industrial interest in measurement of displacement, velocity, acceleration, or a contribution of them for machinery condition monitoring. Considering this criterion in quadratic optimal control systems, a special style of performance index is configured. Utilizing the current relations in an aeroelastic case with proper attachment of piezoelectric elements can provide higher margin of instability and lead to lower vibration magnitude.

  19. Semi-active vibration absorber based on real-time controlled MR damper (United States)

    Weber, F.


    A semi-active vibration absorber with real-time controlled magnetorheological damper (MR-SVA) for the mitigation of harmonic structural vibrations is presented. The MR damper force targets to realize the frequency and damping adaptations to the actual structural frequency according to the principle of the undamped vibration absorber. The relative motion constraint of the MR-SVA is taken into account by an adaptive nonlinear control of the internal damping of the MR-SVA. The MR-SVA is numerically and experimentally validated for harmonic excitation of the primary structure when the natural frequency of the passive mass spring system of the MR-SVA is correctly tuned to the targeted structural resonance frequency and when de-tuning is present. The results demonstrate that the MR-SVA outperforms the passive TMD at structural resonance frequency by at least 12.4% and up to 60.0%.

  20. Analytical design and evaluation of an active control system for helicopter vibration reduction and gust response alleviation (United States)

    Taylor, R. B.; Zwicke, P. E.; Gold, P.; Miao, W.


    An analytical study was conducted to define the basic configuration of an active control system for helicopter vibration and gust response alleviation. The study culminated in a control system design which has two separate systems: narrow band loop for vibration reduction and wider band loop for gust response alleviation. The narrow band vibration loop utilizes the standard swashplate control configuration to input controller for the vibration loop is based on adaptive optimal control theory and is designed to adapt to any flight condition including maneuvers and transients. The prime characteristics of the vibration control system is its real time capability. The gust alleviation control system studied consists of optimal sampled data feedback gains together with an optimal one-step-ahead prediction. The prediction permits the estimation of the gust disturbance which can then be used to minimize the gust effects on the helicopter.

  1. SKA CSP controls: technological challenges (United States)

    Baffa, C.; Giani, E.; Vrcic, S.; Vela Nuñez, M.


    The Square Kilometer Array (SKA) project is an international effort to build the world's largest radio telescope, with eventually over a square kilometer of collecting area. For SKA Phase 1, Australia will host the low-frequency instrument with more than 500 stations, each containing around 250 individual antennas, whilst South Africa will host an array of close to 200 dishes. The scale of the SKA represents a huge leap forward in both engineering and research and development towards building and delivering a unique instrument, with the detailed design and preparation now well under way. As one of the largest scientific endeavors in history, the SKA will brings together close to 100 organizations from 20 countries. Every aspect of the design and development of such a large and complex instrument requires state-of-the-art technology and innovative approach. This poster (or paper) addresses some aspects of the SKA monitor and control system, and in particular describes the development and test results of the CSP Local Monitoring and Control prototype. At the SKA workshop held in April 2015, the SKA monitor and control community has chosen TANGO Control System as a framework, for the implementation of the SKA monitor and control. This decision will have a large impact on Monitor an Control development of SKA. As work is on the way to incorporate TANGO Control System in SKA is in progress, we started to development a prototype for the SKA Central Signal Processor to mitigate the associated risks. In particular we now have developed a uniform class schema proposal for the sub-Element systems of the SKA-CSP.

  2. A fuzzy robust control scheme for vibration suppression of a nonlinear electromagnetic-actuated flexible system (United States)

    Tavakolpour-Saleh, A. R.; Haddad, M. A.


    In this paper, a novel robust vibration control scheme, namely, one degree-of-freedom fuzzy active force control (1DOF-FAFC) is applied to a nonlinear electromagnetic-actuated flexible plate system. First, the flexible plate with clamped-free-clamped-free (CFCF) boundary conditions is modeled and simulated. Then, the validity of the simulation platform is evaluated through experiment. A nonlinear electromagnetic actuator is developed and experimentally modeled through a parametric system identification scheme. Next, the obtained nonlinear model of the actuator is applied to the simulation platform and performance of the proposed control technique in suppressing unwanted vibrations is investigated via simulation. A fuzzy controller is applied to the robust 1DOF control scheme to tune the controller gain using acceleration feedback. Consequently, an intelligent self-tuning vibration control strategy based on an inexpensive acceleration sensor is proposed in the paper. Furthermore, it is demonstrated that the proposed acceleration-based control technique owns the benefits of the conventional velocity feedback controllers. Finally, an experimental rig is developed to investigate the effectiveness of the 1DOF-FAFC scheme. It is found that the first, second, and third resonant modes of the flexible system are attenuated up to 74%, 81%, and 90% respectively through which the effectiveness of the proposed control scheme is affirmed.

  3. Robust and fast schemes in broadband active noise and vibration control

    NARCIS (Netherlands)

    Fraanje, P.R.


    This thesis presents robust and fast active control algorithms for the suppression of broadband noise and vibration disturbances. Noise disturbances, e.g., generated by engines in airplanes and cars or by air ow, can be reduced by means of passive or active methods.

  4. Early vibration assisted physiotherapy in toddlers with cerebral palsy - a randomized controlled pilot trial

    NARCIS (Netherlands)

    Stark, C.; Herkenrath, P.; Hollmann, H.; Waltz, S.; Becker, I.; Hoebing, L.; Semler, O.; Hoyer-Kuhn, H.; Duran, I.; Hero, B.; Hadders-Algra, M.; Schoenau, E.

    OBJECTIVES: to investigate feasibility, safety and efficacy of home-based side-alternating whole body vibration (sWBV) to improve motor function in toddlers with cerebral palsy (CP). METHODS: Randomized controlled trial including 24 toddlers with CP (mean age 19 months (SD±3.1); 13 boys).

  5. Wind-Tunnel Tests of a Bridge Model with Active Vibration Control

    DEFF Research Database (Denmark)

    Hansen, H. I.; Thoft-Christensen, Palle; Mendes, P. A.

    The application of active control systems to reduce wind vibrations in bridges is a new area of research. This paper presents the results that were obtained on a set of wind tunnel tests of a bridge model equipped with active movable flaps. Based on the monitored position and motion of the deck...

  6. Influence of controlling vibrations on heat transfer in floating zone crystal growth* (United States)

    Fedyushkin, A. I.

    The crystal growth processes of monocrystals are strongly vibrational sensitive systems and in particular it concerns to a floating zone method as presence of a free surface and two fronts of crystallization and melting that aggravate it The given work is devoted to numerical investigations of the influence of controlling vibrations on heat transfer during crystal growth by floating zone technique Normal and weightless environment conditions are considered Mathematical simulation is performed on the numerical solutions of basis unsteady Navier-Stokes equations for incompressible fluid flows and energy equation 2D axisymmetric geometry was used in model Marangoni convection and radiation condition on the curvature free surface were taken in account The calculations of the shape of a free surface of a liquid zone and influences on it of a corner of wetting force of weight and size of factor of a superficial tension are carried out The simulations of convective heat transfer for real curvature free surface of a liquid zone with and without the taking into account of the following factors parameters of radiation rotations natural and Marangoni convection and vibrations are carried out The given calculations are carried out for semiconductors melts with Prandtl number Pr 1 and for oxides Pr 1 The influence of vibrations of a crystal on melt flow and on the wide of dynamic and thermal boundary layers at melt-crystal interface is studied The action of vibrations on an enhancement of heat fluxes at the melt crystal interface is shown

  7. An adaptive left-right eigenvector evolution algorithm for vibration isolation control (United States)

    Wu, T. Y.


    The purpose of this research is to investigate the feasibility of utilizing an adaptive left and right eigenvector evolution (ALREE) algorithm for active vibration isolation. As depicted in the previous paper presented by Wu and Wang (2008 Smart Mater. Struct. 17 015048), the structural vibration behavior depends on both the disturbance rejection capability and mode shape distributions, which correspond to the left and right eigenvector distributions of the system, respectively. In this paper, a novel adaptive evolution algorithm is developed for finding the optimal combination of left-right eigenvectors of the vibration isolator, which is an improvement over the simultaneous left-right eigenvector assignment (SLREA) method proposed by Wu and Wang (2008 Smart Mater. Struct. 17 015048). The isolation performance index used in the proposed algorithm is defined by combining the orthogonality index of left eigenvectors and the modal energy ratio index of right eigenvectors. Through the proposed ALREE algorithm, both the left and right eigenvectors evolve such that the isolation performance index decreases, and therefore one can find the optimal combination of left-right eigenvectors of the closed-loop system for vibration isolation purposes. The optimal combination of left-right eigenvectors is then synthesized to determine the feedback gain matrix of the closed-loop system. The result of the active isolation control shows that the proposed method can be utilized to improve the vibration isolation performance compared with the previous approaches.

  8. Prediction and Control of Cutting Tool Vibration in Cnc Lathe with Anova and Ann

    Directory of Open Access Journals (Sweden)

    S. S. Abuthakeer


    Full Text Available Machining is a complex process in which many variables can deleterious the desired results. Among them, cutting tool vibration is the most critical phenomenon which influences dimensional precision of the components machined, functional behavior of the machine tools and life of the cutting tool. In a machining operation, the cutting tool vibrations are mainly influenced by cutting parameters like cutting speed, depth of cut and tool feed rate. In this work, the cutting tool vibrations are controlled using a damping pad made of Neoprene. Experiments were conducted in a CNC lathe where the tool holder is supported with and without damping pad. The cutting tool vibration signals were collected through a data acquisition system supported by LabVIEW software. To increase the buoyancy and reliability of the experiments, a full factorial experimental design was used. Experimental data collected were tested with analysis of variance (ANOVA to understand the influences of the cutting parameters. Empirical models have been developed using analysis of variance (ANOVA. Experimental studies and data analysis have been performed to validate the proposed damping system. Multilayer perceptron neural network model has been constructed with feed forward back-propagation algorithm using the acquired data. On the completion of the experimental test ANN is used to validate the results obtained and also to predict the behavior of the system under any cutting condition within the operating range. The onsite tests show that the proposed system reduces the vibration of cutting tool to a greater extend.

  9. Optimal and robust feedback controller estimation for a vibrating plate

    NARCIS (Netherlands)

    Fraanje, P.R.; Verhaegen, M.; Doelman, N.J.; Berkhoff, A.


    This paper presents a method to estimate the H2 optimal and a robust feedback controller by means of Subspace Model Identification using the internal model control (IMC) approach. Using IMC an equivalent feed forward control problem is obtained, which is solved by the Causal Wiener filter for the H2

  10. A feedback control system for vibration of magnetostrictive plate subjected to follower force using sinusoidal shear

    Directory of Open Access Journals (Sweden)

    A. Ghorbanpour Arani


    Full Text Available In this research, the vibrational behavior of magnetostrictive plate (MsP as a smart component is studied. The plate is subjected to an external follower force and a magnetic field in which the vibration response of MsP has been investigated for both loading combinations. The velocity feedback gain parameter is evaluated to study the effect of magnetic field which is generated by the coil. Sinusoidal shear deformation theory is utilized due to its accuracy of polynomial function with respect to other plate theories. Equations of motion are derived using Hamilton’s principle and solved by differential quadrature method (DQM considering general boundary conditions. The effects of aspect ratio, thickness ratio, follower force and velocity feedback gain are investigated on the frequency response of MsP. Results indicate that magneto-mechanical coupling in MsM helps to control vibrational behaviors of systems such as electro-hydraulic actuator, wireless linear Motors and sensors.

  11. Vibration Isolation and Trajectory Following Control of a Cable Suspended Stewart Platform

    Directory of Open Access Journals (Sweden)

    Xuechao Duan


    Full Text Available To achieve high-quality vibration isolation and trajectory following control of a cable driven parallel robot based Stewart platform in the five hundred meter aperture spherical radio telescope (FAST design, the integrated dynamic model of the Stewart platform including the electric cylinder is established in this paper, the globally feedback linearization of the dynamic model is implemented based on the control law partitioning approach. To overcome the disadvantages of the external disturbance on the base and unmodeled flexibility of the mechanism, a PID (Proportional-Derivative-Integral controller with base acceleration feedforward is designed in the operational space of the Stewart platform. Experiments of the vibration isolation and trajectory following control of the cable suspended Stewart platform with presence of the base disturbance is carried out. The experimental results show that the presented control scheme has the advantage of stable dynamics, high accuracy and strong robustness.

  12. A Novel Adaptive PID Controller with Application to Vibration Control of a Semi-Active Vehicle Seat Suspension

    Directory of Open Access Journals (Sweden)

    Do Xuan Phu


    Full Text Available This work proposes a novel adaptive hybrid controller based on the sliding mode controller and H-infinity control technique, and its effectiveness is verified by implementing it in vibration control of a vehicle seat suspension featuring a magneto-rheological damper. As a first step, a sliding surface of the sliding mode controller is established and used as a bridge to formulate the proposed controller. In this process, two matrices such as Hurwitz constants matrix are used as components of the sliding surface and H-infinity technique are adopted to achieve robust stability. Secondly, a fuzzy logic model based on the interval type 2 fuzzy model which is featured by online clustering is established and integrated to take account for external disturbances. Subsequently, a new adaptive hybrid controller is formulated with a solid proof of the robust stability. Then, the effectiveness is demonstrated by implementing the proposed hybrid controller on the vibration control of a vehicle seat suspension associated with a controllable damper. Vibration control performances are evaluated on bump and random road profiles by presenting both displacement and acceleration on the seat and the driver positions. In addition, a comparative study between the proposed and one of existing controllers is undertaken to highlight some benefits of the hybrid adaptive controller developed in this work.

  13. Analysis and testing of an integrated semi-active seat suspension for both longitudinal and vertical vibration control (United States)

    Bai, Xian-Xu; Jiang, Peng; Pan, Hui; Qian, Li-Jun


    An integrated semi-active seat suspension for both longitudinal and vertical vibration control is analyzed and tested in this paper. The seat suspension consists of a switching mechanism transforming both longitudinal and vertical motions into a rotary motion and a real-time damping-controllable system-a rotary magnetorheological (MR) damper working in pure shear mode and its corresponding control system. The switching mechanism employs the parallelogram frames as a motion guide which keeps the seat moving longitudinally and vertically. At the same time, both longitudinal and vertical motions are transformed into a reciprocating rotary motion that is transmitted to the rotary MR damper after an amplification by a gear mechanism. Both the longitudinal and vertical vibrations can be attenuated in real time through controlling the damping force (or torque) of the rotary MR damper. The mathematical model of the seat suspension system is established, simulated, and analyzed. The experimental test based on the test rig in Hefei University of Technology is implemented, and the results of simulation and experimental test are compared and analyzed.

  14. Effect of Space Vehicle Structure Vibration on Control Moment Gyroscope Dynamics (United States)

    Dobrinskaya, Tatiana


    Control Moment Gyroscopes (CMGs) are used for non-propulsive attitude control of satellites and space stations, including the International Space Station (ISS). CMGs could be essential for future long duration space missions due to the fact that they help to save propellant. CMGs were successfully tested on the ground for many years, and have been successfully used on satellites. However, operations have shown that the CMG service life on the ISS is significantly shorter than predicted. Since the dynamic environment of the ISS differs greatly from the nominal environment of satellites, it was important to analyze how operations specific to the station (dockings and undockings, huge solar array motion, crew exercising, robotic operations, etc) can affect the CMG performance. This task became even more important since the first CMG failure onboard the ISS. The CMG failure resulted in the limitation of the attitude control capabilities, more propellant consumption, and additional operational issues. Therefore, the goal of this work was to find out how the vibrations of a space vehicle structure, caused by a variety of onboard operations, can affect the CMG dynamics and performance. The equations of CMG motion were derived and analyzed for the case when the gyro foundation can vibrate in any direction. The analysis was performed for unbalanced CMG gimbals to match the CMG configuration on ISS. The analysis showed that vehicle structure vibrations can amplify and significantly change the CMG motion if the gyro gimbals are unbalanced in flight. The resonance frequencies were found. It was shown that the resonance effect depends on the magnitude of gimbal imbalance, on the direction of a structure vibration, and on gimbal bearing friction. Computer modeling results of CMG dynamics affected by the external vibration are presented. The results can explain some of the CMG vibration telemetry observed on ISS. This work shows that balancing the CMG gimbals decreases the effect

  15. Adaptive Gain Scheduled Semiactive Vibration Control Using a Neural Network

    Directory of Open Access Journals (Sweden)

    Kazuhiko Hiramoto


    Full Text Available We propose an adaptive gain scheduled semiactive control method using an artificial neural network for structural systems subject to earthquake disturbance. In order to design a semiactive control system with high control performance against earthquakes with different time and/or frequency properties, multiple semiactive control laws with high performance for each of multiple earthquake disturbances are scheduled with an adaptive manner. Each semiactive control law to be scheduled is designed based on the output emulation approach that has been proposed by the authors. As the adaptive gain scheduling mechanism, we introduce an artificial neural network (ANN. Input signals of the ANN are the measured earthquake disturbance itself, for example, the acceleration, velocity, and displacement. The output of the ANN is the parameter for the scheduling of multiple semiactive control laws each of which has been optimized for a single disturbance. Parameters such as weight and bias in the ANN are optimized by the genetic algorithm (GA. The proposed design method is applied to semiactive control design of a base-isolated building with a semiactive damper. With simulation study, the proposed adaptive gain scheduling method realizes control performance exceeding single semiactive control optimizing the average of the control performance subject to various earthquake disturbances.

  16. Regular physical activity reduces the effects of Achilles tendon vibration on postural control for older women. (United States)

    Maitre, J; Serres, I; Lhuisset, L; Bois, J; Gasnier, Y; Paillard, T


    The aim was to determine in what extent physical activity influences postural control when visual, vestibular, and/or proprioceptive systems are disrupted. Two groups of healthy older women: an active group (74.0 ± 3.8 years) who practiced physical activities and a sedentary group (74.7 ± 6.3 years) who did not, underwent 12 postural conditions consisted in altering information emanating from sensory systems by means of sensory manipulations (i.e., eyes closed, cervical collar, tendon vibration, electromyostimulation, galvanic vestibular stimulation, foam surface). The center of foot pressure velocity was recorded on a force platform. Results indicate that the sensory manipulations altered postural control. The sedentary group was more disturbed than the active group by the use of tendon vibration. There was no clear difference between the two groups in the other conditions. This study suggests that the practice of physical activities is beneficial as a means of limiting the effects of tendon vibration on postural control through a better use of the not manipulated sensory systems and/or a more efficient reweighting to proprioceptive information from regions unaffected by the tendon vibration. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Controlling vibrational cooling with zero-width resonances: An adiabatic Floquet approach (United States)

    Leclerc, Arnaud; Viennot, David; Jolicard, Georges; Lefebvre, Roland; Atabek, Osman


    In molecular photodissociation, some specific combinations of laser parameters (wavelength and intensity) lead to unexpected zero-width resonances (ZWRs) with, in principle, infinite lifetimes. Their potential to induce basic quenching mechanisms has recently been devised in the laser control of vibrational cooling through filtration strategies [O. Atabek et al., Phys. Rev. A 87, 031403(R) (2013), 10.1103/PhysRevA.87.031403]. A full quantum adiabatic control theory based on the adiabatic Floquet Hamiltonian is developed to show how a laser pulse could be envelope-shaped and frequency-chirped so as to protect a given initial vibrational state against dissociation, taking advantage of its continuous transport on the corresponding ZWR all along the pulse duration. As compared with previous control scenarios that actually suffered from nonadiabatic contamination, drastically different and much more efficient filtration goals are achieved. A semiclassical analysis helps us to find and interpret a complete map of ZWRs in the laser parameter plane. In addition, the choice of a given ZWR path, among the complete series identified by the semiclassical approach, turns out to be crucial for the cooling scheme, targeting a single vibrational state population left at the end of the pulse, while all others have almost completely decayed. The illustrative example, which has the potential to be transposed to other diatomics, is Na2 prepared by photoassociation in vibrationally hot but translationally and rotationally cold states.

  18. Development of flow separation control system to reduce the vibration of wind turbine blades (United States)

    Kim, Ho-Young; Kim, Ho-Hyun; Han, Jong-Seob; Han, Jae-Hung


    The size of wind turbine blade has been continuously increased. Large-scale wind turbine blades induce loud noise, vibration; and maintenance difficulty is also increased. It causes the eventual increases of the cost of energy. The vibration of wind turbine blade is caused by several reasons such as a blade rotation, tower shadow, wind shear, and flow separation of a wind turbine blade. This wind speed variation changes in local angle of attack of the blades and create the vibration. The variation of local angle of attack influences the lift coefficient and causes the large change of the lift. In this study, we focus on the lift coefficient control using a flow control device to reduce the vibration. DU35-A15 airfoil was employed as baseline model. A plasma actuator was installed to generate the upwind jet in order to control the lift coefficient. Wind tunnel experiment was performed to demonstrate of the performance of the plasma actuator. The results show the plasma actuator can induce the flow separation compared with the baseline model. In addition, the actuator can delay the flow separation depending on the input AC frequency with the same actuator configuration.

  19. Vibration control of a flexible structure with electromagnetic actuators

    DEFF Research Database (Denmark)

    Gruzman, Maurício; Santos, Ilmar


    elements were used. Nonlinear equations for the actuator electromagnetic force, noise in the position sensor, time delays for the control signal update and voltage saturation were also considered in the model. For controlling purposes, a discrete linear quadratic regulator combined with a predictive full...

  20. Finite element based model predictive control for active vibration suppression of a one-link flexible manipulator. (United States)

    Dubay, Rickey; Hassan, Marwan; Li, Chunying; Charest, Meaghan


    This paper presents a unique approach for active vibration control of a one-link flexible manipulator. The method combines a finite element model of the manipulator and an advanced model predictive controller to suppress vibration at its tip. This hybrid methodology improves significantly over the standard application of a predictive controller for vibration control. The finite element model used in place of standard modelling in the control algorithm provides a more accurate prediction of dynamic behavior, resulting in enhanced control. Closed loop control experiments were performed using the flexible manipulator, instrumented with strain gauges and piezoelectric actuators. In all instances, experimental and simulation results demonstrate that the finite element based predictive controller provides improved active vibration suppression in comparison with using a standard predictive control strategy. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Research on the Random Shock Vibration Test Based on the Filter-X LMS Adaptive Inverse Control Algorithm

    Directory of Open Access Journals (Sweden)

    Wang Wei


    Full Text Available The related theory and algorithm of adaptive inverse control were presented through the research which pointed out the adaptive inverse control strategy could effectively eliminate the noise influence on the system control. Proposed using a frequency domain filter-X LMS adaptive inverse control algorithm, and the control algorithm was applied to the two-exciter hydraulic vibration test system of random shock vibration control process and summarized the process of the adaptive inverse control strategies in the realization of the random shock vibration test. The self-closed-loop and field test show that using the frequency-domain filter-X LMS adaptive inverse control algorithm can realize high precision control of random shock vibration test.

  2. Vibration control for a rigid-flexible manipulator with full state constraints via Barrier Lyapunov Function (United States)

    Cao, Fangfei; Liu, Jinkun


    Considering full state constraints, this paper designs a boundary controller for a two-link rigid-flexible manipulator via Barrier Lyapunov Function. The dynamic model of the two-link rigid-flexible manipulator is described by coupled ordinary differential equations- partial differential equations (ODEs-PDEs). Based on the original model without neglecting the high-frequency modes, boundary controller is proposed to regulate the joint positions and eliminate the elastic vibration simultaneously. To ensure that the full state constraints which include position, speed and vibration constraints are not transgressed, a Barrier Lyapunov Function is employed in the proposed controller. The asymptotic stability of the closed-loop system is rigorously proved by the LaSalle's Invariance Principle. Simulations are given to verify the effectiveness of the proposed controller with state constraints.

  3. Novel controller design demonstration for vibration alleviation of helicopter rotor blades (United States)

    Ulker, Fatma Demet; Nitzsche, Fred


    This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor sys- tems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-delity aeroelastic simulations. To validate the con- troller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations.

  4. Adaptive Model Predictive Vibration Control of a Cantilever Beam with Real-Time Parameter Estimation

    Directory of Open Access Journals (Sweden)

    Gergely Takács


    Full Text Available This paper presents an adaptive-predictive vibration control system using extended Kalman filtering for the joint estimation of system states and model parameters. A fixed-free cantilever beam equipped with piezoceramic actuators serves as a test platform to validate the proposed control strategy. Deflection readings taken at the end of the beam have been used to reconstruct the position and velocity information for a second-order state-space model. In addition to the states, the dynamic system has been augmented by the unknown model parameters: stiffness, damping constant, and a voltage/force conversion constant, characterizing the actuating effect of the piezoceramic transducers. The states and parameters of this augmented system have been estimated in real time, using the hybrid extended Kalman filter. The estimated model parameters have been applied to define the continuous state-space model of the vibrating system, which in turn is discretized for the predictive controller. The model predictive control algorithm generates state predictions and dual-mode quadratic cost prediction matrices based on the updated discrete state-space models. The resulting cost function is then minimized using quadratic programming to find the sequence of optimal but constrained control inputs. The proposed active vibration control system is implemented and evaluated experimentally to investigate the viability of the control method.

  5. Robust tracking control for linear vibrating mechanical systems

    Directory of Open Access Journals (Sweden)

    Francisco Beltrán-Carbajal


    Full Text Available Se propone un enfoque de control novedoso para seguimiento por realimentación de la salida para sistemas mecánicos vibratorios del tipo masa-resorte-amortiguador lineales sub-actuados. La metodología de diseño de control que se presenta considera robustez con respecto de dinámicas no modeladas y fuerzas externas. El esquema de control propuesto solamente requiere mediciones de la variable de la salida de posición. Se utiliza compensación integral del error de seguimiento de manera apropiada para evitar la estimación en tiempo real de las perturbaciones. Resultado analíticos y numéricos muestran la efectividad del esquema de control activo de vibración para atenuación de vibraciones resonantes y caóticas afectando la respuesta de la variable de salida.

  6. The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients (United States)

    Abboud, Jacques; Nougarou, François; Normand, Martin C.


    Introduction Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. Methods Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). Results Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. Conclusions Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle

  7. The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients.

    Directory of Open Access Journals (Sweden)

    Jean-Alexandre Boucher

    Full Text Available Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP. This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control.Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE, variable error (VE as well as absolute error (AE in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG.Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm. Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm and AE (13.71 ± 3.45 Nm mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm and AE (16.29 ± 2.82 Nm mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores.Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration

  8. The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients. (United States)

    Boucher, Jean-Alexandre; Abboud, Jacques; Nougarou, François; Normand, Martin C; Descarreaux, Martin


    Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation

  9. Improved Object Detection Using a Robotic Sensing Antenna with Vibration Damping Control. (United States)

    Feliu-Batlle, Vicente; Feliu-Talegon, Daniel; Castillo-Berrio, Claudia Fernanda


    Some insects or mammals use antennae or whiskers to detect by the sense of touch obstacles or recognize objects in environments in which other senses like vision cannot work. Artificial flexible antennae can be used in robotics to mimic this sense of touch in these recognition tasks. We have designed and built a two-degree of freedom (2DOF) flexible antenna sensor device to perform robot navigation tasks. This device is composed of a flexible beam, two servomotors that drive the beam and a load cell sensor that detects the contact of the beam with an object. It is found that the efficiency of such a device strongly depends on the speed and accuracy achieved by the antenna positioning system. These issues are severely impaired by the vibrations that appear in the antenna during its movement. However, these antennae are usually moved without taking care of these undesired vibrations. This article proposes a new closed-loop control schema that cancels vibrations and improves the free movements of the antenna. Moreover, algorithms to estimate the 3D beam position and the instant and point of contact with an object are proposed. Experiments are reported that illustrate the efficiency of these proposed algorithms and the improvements achieved in object detection tasks using a control system that cancels beam vibrations.

  10. Jerk Control for Vibration Suppression of an Uncertain Mechanical Transfer System with a Flexible Beam (United States)

    Miura, Takahiro; Ikeda, Masao; Hoshijima, Kohta

    High productivity is commonly required in manufacturing processes. For this purpose, we need to run machines at high speed. However, high-speed motion usually generates vibration in positioning and then makes the settling time long. For this reason, various control strategies have been proposed for high-speed motion and vibration suppression at the same time. In this paper, we deal with a mechanical transfer system with a loading beam, which is widely used in manufacturing processes. We represent the system as composed of three rigid bodies, that is, a driving unit, a hand, and a work. The driving unit and the hand are connected by an elastic link, and slide on a smooth floor. The work is loaded on a flexible beam which is connected rigidly to the hand. When the driving unit moves on the floor, the work is vibrated not only in the translational motion but also in the bending motion because of the flexibility of the beam. Under polytopic uncertainties of the stiffness and damping parameters in the link and the beam, we apply the idea of jerk reduction control to the hand for vibration suppression of the work and shortening the settling time in positioning. We show the effectiveness of jerk reduction of the hand by numerical simulations for a finite element model.

  11. Vibration reduction in helicopter rotors using an active control surface located on the blade (United States)

    Millott, T. A.; Friedmann, P. P.


    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  12. The use of hybrid automata for fault-tolerant vibration control for parametric failures (United States)

    Byreddy, Chakradhar; Frampton, Kenneth D.; Yongmin, Kim


    The purpose of this work is to make use of hybrid automata for vibration control reconfiguration under system failures. Fault detection and isolation (FDI) filters are used to monitor an active vibration control system. When system failures occur (specifically parametric faults) the FDI filters detect and identify the specific failure. In this work we are specifically interested in parametric faults such as changes in system physical parameters; however this approach works equally well with additive faults such as sensor or actuator failures. The FDI filter output is used to drive a hybrid automaton, which selects the appropriate controller and FDI filter from a library. The hybrid automata also implements switching between controllers and filters in order to maintain optimal performance under faulty operating conditions. The biggest challenge in developing this system is managing the switching and in maintaining stability during the discontinuous switches. Therefore, in addition to vibration control, the stability associated with switching compensators and FDI filters is studied. Furthermore, the performance of two types of FDI filters is compared: filters based on parameter estimation methods and so called "Beard-Jones" filters. Finally, these simulations help in understanding the use of hybrid automata for fault-tolerant control.

  13. Finite Element Analysis and Vibration Control of a Deep Composite Cylindrical Shell Using MFC Actuators

    Directory of Open Access Journals (Sweden)

    Gangolu Vijay Kumar


    Full Text Available A four-node composite facet-shell element is developed, accounting for electromechanical coupling of Macrofiber Composite (MFC and conventional PZT patches. Further a warping correction is included in order to capture correctly the induced strain of conformable MFC, surface bonded on a cylindrical shell. The element performance to model the relations between in-plane electric field to normal strains is examined with the help of experiment and ANSYS analysis. In ANSYS, a simple modeling scheme is proposed for MFC using a parallel capacitors concept. The independent modal space control technique has been revisited to address the control of combination resonances through a selective modal space control scheme, where two or more modes can be combined to form the vibrating system or plant in modal domain. The developed control schemes are implemented in a digital processor using DS1104 and the closed-loop vibration control experiments are conducted on a CFRP shell structure. The influence of directionally induced actuation of MFC actuators on elastic couplings of composite shell is studied theoretically and is subsequently demonstrated in experiments. MFC actuators provide the much needed optimization domain for achieving the vibration control of combination resonances of elastically coupled deep-shell structure.

  14. Effects of aerobic exercise and whole body vibration on glycaemia control in type 2 diabetic males. (United States)

    Behboudi, Lale; Azarbayjani, Mohammad-Ali; Aghaalinejad, Hamid; Salavati, Mahyar


    Aerobic exercise has been identified as the main treatment for type 2 diabetic patients. Such an exercise, however, is usually repined by some of patients who suffer from lack of stamina. Therefore, whole body vibration has recently been introduced as a passive intervention. The present study aimed at comparing how aerobic exercise and whole body vibration affect glycaemia control in type 2 diabetic males. Thirty diabetic males were divided into three groups, namely aerobic exercise (AE), whole body vibration (WBV), and control. Aerobic exercise schedule consisted of three walking sessions a week, each for 30-60 minutes and in 60-70% of maximum stock heartbeat. Vibration exercise was composed of 8-12-min stand-up and semi-squat positioning in frequency of 30 Hz and amplitude of 2 mm. Concentrations of fasting glycosylated hemoglobin, fasting glucose, and insulin were measured in the beginning of the trial, after the fourth week, and after the eighth week. After 8 weeks of exercise, no significant difference was detected in concentrations of fasting glycosylated hemoglobin and insulin between the groups (P=0.83, P=0.12). There were no significant differences in any of the variables between AE and WBV (P>0.05). But a more significant decrease in fasting glucose was observed in exercise groups (AE and WBV) compared with control group (P=0.02). The present study showed that AE and WBV identically stimulate metabolic system. Thus, it can be concluded that type 2 diabetic patients lacking stamina for aerobic exercise can opt for vibration exercise as an effective substitute.

  15. Quantum coherent control of the vibrational dynamics of a ...

    Indian Academy of Sciences (India)


    Feb 12, 2014 ... We simulate adaptive feedback control to coherently shape a femtosecond infrared laser pulse by means of a 4f-spatial light modulator in order to selectively excite the rovibrational modes of a polyatomic molecule. We preferentially populate an arbitrarily chosen upper rovibrational level by only employing ...

  16. Wireless Sensor Network for Helicopter Rotor Blade Vibration Monitoring: Requirements Definition and Technological Aspects

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Das, Kallol; Loendersloot, Richard; Tinga, Tiedo; Havinga, Paul J.M.; Basu, Biswajit

    The main rotor accounts for the largest vibration source for a helicopter fuselage and its components. However, accurate blade monitoring has been limited due to the practical restrictions on instrumenting rotating blades. The use of Wireless Sensor Networks (WSNs) for real time vibration monitoring

  17. Experimental Verifications of Vibration Suppression for a Smart Cantilever Beam with a Modified Velocity Feedback Controller

    Directory of Open Access Journals (Sweden)

    Ting Zhang


    Full Text Available This paper presents various experimental verifications for the theoretical analysis results of vibration suppression to a smart flexible beam bonded with a piezoelectric actuator by a velocity feedback controller and an extended state observer (ESO. During the state feedback control (SFC design process for the smart flexible beam with the pole placement theory, in the state feedback gain matrix, the velocity feedback gain is much more than the displacement feedback gain. For the difference between the velocity feedback gain and the displacement feedback gain, a modified velocity feedback controller is applied based on a dynamical model with the Hamilton principle to the smart beam. In addition, the feedback velocity is attained with the extended state observer and the displacement is acquired by the foil gauge on the root of the smart flexible beam. The control voltage is calculated by the designed velocity feedback gain multiplied by the feedback velocity. Through some experiment verifications for simulation results, it is indicated that the suppressed amplitude of free vibration is up to 62.13% while the attenuated magnitude of its velocity is up to 61.31%. Therefore, it is demonstrated that the modified velocity feedback control with the extended state observer is feasible to reduce free vibration.

  18. Smart panel with time-varying shunted piezoelectric patch absorbers for broadband vibration control (United States)

    Casagrande, D.; Gardonio, P.; Zilletti, M.


    This paper presents a simulation study concerning the low and mid frequencies control of flexural vibration in a lightly damped thin plate equipped with five time-varying shunted piezoelectric patch absorbers. The panel is excited by a rain-on-the-roof broad frequency band stationary disturbance. The absorbers are composed by piezoelectric patches connected to time-varying RL shunt circuits. Discrete or continuous variations over time of the shunts are implemented in such a way as to either switch, between given values, or sweep, within certain ranges, the natural frequency and damping factor of the electro-mechanical absorbers to control either the resonant response of targeted flexural modes of the plate with natural frequency comprised between 30 Hz and 1 kHz or to control the resonant responses of all flexural modes with natural frequencies comprised between 30 Hz and 1 kHz. The proposed system is firstly presented; then, the vibration control effects produced by a single patch and by the array of five patches implementing the switching and sweeping shunts are investigated. Both time-varying operation modes produce significant vibration control effects, with reductions of the resonance peaks of the target resonances or target frequency band up to 12 dB. The piezoelectric patch absorbers with sweeping shunts offer an interesting practical solution since they are operated blindly, thus they do not require a system identification during installation and effectively work without on line tuning also on systems whose response may vary substantially in time.

  19. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber (United States)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei


    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  20. The use of Classical Rolling Pendulum Bearings (CRPB for vibration control of stay-cables

    Directory of Open Access Journals (Sweden)

    Papastergiou Georgia


    Full Text Available Cables are efficient structural elements that are used in cable-stayed bridges, suspension bridges and other cable structures. A significant problem which arose from the praxis is the cables’ rain-wind induced vibrations as these cables are subjected to environmental excitations. Rain-wind induced stay-cable vibrations may occur at different cable eigenfrequencies. Large amplitude Rain-Wind-Induced-Vibrations (RWIV of stay cables are a challenging problem in the design of cable-stayed bridges. Several methods, including aerodynamic or structural means, have been investigated in order to control the vibrations of bridge’s stay-cables. The present research focuses on the effectiveness of a movable anchorage system with a Classical Rolling Pendulum Bearing (CRPB device. An analytical model of cable-damper system is developed based on the taut string representation of the cable. The gathered integral-differential equations are solved through the use of the Lagrange transformation. . Finally, a case study with realistic geometrical parameters is also presented to establish the validity of the proposed system.

  1. Diagnosis and control of machine induced noise and vibration in steel construction

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei Yu; Wang, Wei Hui [National Taiwan Ocean University, Keelung (China)


    Most high-rise buildings constructed of steel or steel reinforced concrete have to install various vital equipment. Among these equipment machinery noise is especially annoying for accommodation close to them. In attempting to control the machine-induced structure-borne noise and vibration, the methodology by employing mobility functions to identify the dominant frequency band of vibrational power flow transmission and to assess the isolation effectiveness of isolators is established. The proposed method of diagnosis procedure is applied to the structure-borne vibration power flow transmission for a steel construction parking tower. After proper check and replacement of the isolators of the power unit platform of the mechanical parking tower, the improvement results in a substantial structure-borne noise reduction of 16 dB(NC). The unique parts of the paper include the establishment of the relation of mobility functions with respect to four-pole parameters for a coupled machine/mount/foundation system. Also expressions to represent the vibrational input power, the output power and the transmitted power in relation to mobility functions are clarified

  2. Improving Delay-Margin of Noncollocated Vibration Control of Piezo-Actuated Flexible Beams via a Fractional-Order Controller

    Directory of Open Access Journals (Sweden)

    Teerawat Sangpet


    Full Text Available Noncollocated control of flexible structures results in nonminimum-phase systems because the separation between the actuator and the sensor creates an input-output delay. The delay can deteriorate stability of closed-loop systems. This paper presents a simple approach to improve the delay-margin of the noncollocated vibration control of piezo-actuated flexible beams using a fractional-order controller. Results of real life experiments illustrate efficiency of the controller and show that the fractional-order controller has better stability robustness than the integer-order controller.

  3. Optimal location of piezoelectric patches for active vibration control (United States)

    Labanie, Mohammad F.; Ali, J. S. Mohamed; Shaik Dawood, M. S. I.


    This paper focuses on finding the optimal location for a piezoelectric patch for minimizing the settling time of an excited isotropic and orthotropic plate. COMSOL Multiphysics has been used to design and model the plate with PID controller. Classical Optimization tool called Parametric Sweep has been used to achieve the objective of the experiment. Five different stacking sequences were used in the study of orthotropic plate. The results obtained by the FEA software indicated that by placing the piezoelectric patches at the optimal location, the settling time of a plate can decrease by 40% compared to placing it at the centre of the fixed end.

  4. Theoretical and Numerical Experiences on a Test Rig for Active Vibration Control of Mechanical Systems with Moving Constraints

    Directory of Open Access Journals (Sweden)

    M. Rinchi


    Full Text Available Active control of vibrations in mechanical systems has recently benefited of the remarkable development of robust control techniques. These control techniques are able to guarantee performances in spite of unavoidable modeling errors. They have been successfully codified and implemented for vibrating structures whose uncertain parameters could be assumed to be time-invariant. Unfortunately a wide class of mechanical systems, such as machine tools with carriage motion realized by a ball-screw, are characterized by time varying modal parameters. The focus of this paper is on modeling and controlling the vibrations of such systems. A test rig for active vibration control is presented. An analytical model of the test rig is synthesized starting by design data. Through experimental modal analysis, parametric identification and updating procedures, the model has been refined and a control system has been synthesized.

  5. Recent Technology Advances in Distributed Engine Control (United States)

    Culley, Dennis


    This presentation provides an overview of the work performed at NASA Glenn Research Center in distributed engine control technology. This is control system hardware technology that overcomes engine system constraints by modularizing control hardware and integrating the components over communication networks.

  6. Minimum variance control for mitigation of vibrations in adaptive optics systems. (United States)

    Escárate, Pedro; Carvajal, Rodrigo; Close, Laird; Males, Jared; Morzinski, Katie; Agüero, Juan C


    In this paper, we address the design of a minimum variance controller (MVC) for the mitigation of vibrations in modern telescope adaptive optics (AO) systems. It is widely accepted that a main source of non-turbulent perturbations is the mechanical resonance induced by the wind or the instrumentation systems, such as fans and cooling pumps. To adequately mitigate vibrations, the application of frequency-based controllers has been considered in the past decade. In this work, we express the system model in terms of the tracking of a zero-input signal via the MVC. We show that the MVC is an equivalent representation of the linear quadratic Gaussian (LQG) controller for the AO system. We also show that by developing the MVC, we can obtain different expressions, in terms of transfer functions, that offer insights into the behavior and expected performance of the controller in the frequency domain. In addition, we analyze the impact of the accuracy of the system and perturbations model on the mitigation of vibrations.

  7. Experimental Active Vibration Control in Truss Structures Considering Uncertainties in System Parameters

    Directory of Open Access Journals (Sweden)

    Douglas Domingues Bueno


    Full Text Available This paper deals with the study of algorithms for robust active vibration control in flexible structures considering uncertainties in system parameters. It became an area of enormous interest, mainly due to the countless demands of optimal performance in mechanical systems as aircraft, aerospace, and automotive structures. An important and difficult problem for designing active vibration control is to get a representative dynamic model. Generally, this model can be obtained using finite element method (FEM or an identification method using experimental data. Actuators and sensors may affect the dynamics properties of the structure, for instance, electromechanical coupling of piezoelectric material must be considered in FEM formulation for flexible and lightly damping structure. The nonlinearities and uncertainties involved in these structures make it a difficult task, mainly for complex structures as spatial truss structures. On the other hand, by using an identification method, it is possible to obtain the dynamic model represented through a state space realization considering this coupling. This paper proposes an experimental methodology for vibration control in a 3D truss structure using PZT wafer stacks and a robust control algorithm solved by linear matrix inequalities.

  8. Piezoelectric actuator models for active sound and vibration control of cylinders (United States)

    Lester, Harold C.; Lefebvre, Sylvie


    Analytical models for piezoelectric actuators, adapted from flat plate concepts, are developed for noise and vibration control applications associated with vibrating circular cylinders. The loadings applied to the cylinder by the piezoelectric actuators for the bending and in-plane force models are approximated by line moment and line force distributions, respectively, acting on the perimeter of the actuator patch area. Coupling between the cylinder and interior acoustic cavity is examined by studying the modal spectra, particularly for the low-order cylinder modes that couple efficiently with the cavity at low frequencies. Within the scope of this study, the in-plane force model produced a more favorable distribution of low-order modes, necessary for efficient interior noise control, than did the bending model.

  9. Active Vibration Control in a Rotor System by an Active Suspension with Linear Actuators

    Directory of Open Access Journals (Sweden)

    M. Arias-Montiel


    Full Text Available In this paper the problem of modeling, analysis and unbalance response control of a rotor system with two disks in an asymmetrical configuration is treated. The Finite Element Method (FEM is used to get the system model including the gyroscopic effects and then, the obtained model is experimentally validated. Rotordynamic analysis is carried out using the finite element model obtaining the Campbell diagram, the natural frequencies and the critical speeds of the rotor system. An asymptotic observer is designed to estimate the full state vector which is used to synthesize a Linear Quadratic Regulator (LQR to reduce the vibration amplitudes when the system passes through the first critical speed. Some numerical simulations are carried out to verify the closed-loop system behavior. The active vibration control scheme is experimentally validated using an active suspension with electromechanical linear actuators, obtaining significant reductions in the resonant peak.

  10. A New Framework For Helicopter Vibration Suppression; Time-Periodic System Identification and Controller Design (United States)

    Ulker, Fatma Demet

    In forward flight, helicopter rotor blades function within a highly complex aerodynamic environment that includes both near-blade and far-blade aerodynamic phenomena. These aerodynamic phenomena cause fluctuating aerodynamic loads on the rotor blades. These loads when coupled with the dynamic characteristics and elastic motion of the blade create excessive amount of vibration. These vibrations degrade helicopter performance, passenger comfort and contributes to high cost maintenance problems. In an effort to suppress helicopter vibration, recent studies have developed active control strategies using active pitch links, flaps, twist actuation and higher harmonic control of the swash plate. In active helicopter vibration control, designing a controller in a computationally efficient way requires accurate reduced-order models of complex helicopter aeroelasticity. In previous studies, controllers were designed using aeroelastic models that were obtained by coupling independently reduced aerodynamic and structural dynamic models. Unfortunately, these controllers could not satisfy stability and performance criteria when implemented in high-fidelity computer simulations or real-time experiments. In this thesis, we present a novel approach that provides accurate time-periodic reduced-order models and time-periodic H2 and H infinity controllers that satisfy the stability and performance criteria. Computational efficiency and the necessity of using the approach were validated by implementing an actively controlled flap strategy. In this proposed approach, the reduced-order models were directly identified from high-fidelity coupled aeroelastic analysis by using the time-periodic subspace identification method. Time-periodic H2 and Hinfinity controllers that update the control actuation at every time step were designed. The control synthesis problem was solved using Linear Matrix Inequality and periodic Riccati Equation based formulations, for which an in-house periodic

  11. A New Vibration Measurement Procedure for On-Line Quality Control of Electronic Devices

    Directory of Open Access Journals (Sweden)

    Gian Marco Revel


    Full Text Available In this paper the problem of experimentally testing the mechanical reliability of electronic components for quality control is approached. In general, many tests are performed on electronic devices (personal computers, power supply units, lamps, etc., according to the relevant international standards (IEC, in order to verify their resistance to shock and vibrations, but these are mainly “go no-go” experiments, performed on few samples taken from the production batches.

  12. Control strategies applied for reducing the vibration and torque ripple of a special Switched Reluctance Motor


    Correa, D. A. P.; Silva, W. M. da; Nabeta, S. I.; Chabu, I. E.


    Despite its robustness the Switched Reluctance Motors (SRMs) present some inconvenient drawbacks as a major torque ripple, vibration and acoustic noise when compared to other types of motors. These characteristics are usually related to factors such as the salient poles in the stator and in the rotor, the switched feeding and the control strategy imposed by the electronic converter. In this paper a Special Switched Reluctance Motor for fractional horsepower and high speed hand tool was studie...

  13. Recentering Shape Memory Alloy Passive Damper for Structural Vibration Control

    Directory of Open Access Journals (Sweden)

    Hui Qian


    Full Text Available This paper presents a preliminary study on the evaluation of an innovative energy dissipation system with shape memory alloys (SMAs for structural seismic protection. A recentering shape memory alloy damper (RSMAD, in which superelastic nitinol wires are utilized as energy dissipation components, is proposed. Improved constitutive equations based on Graesser and Cozzarelli model are proposed for superelastic nitinol wires used in the damper. Cyclic tensile-compressive tests on the damper with various prestrain under different loading frequencies and displacement amplitudes were conducted. The results show that the hysteretic behaviors of the damper can be modified to best fit the needs for passive structural control applications by adjusting the pretension of the nitinol wires, and the damper performance is not sensitive to frequencies greater than 0.5 Hz. To assess the effectiveness of the dampers for structural seismic protection, nonlinear time history analysis on a ten-story steel frame with and without the dampers subjected to representative earthquake ground motions was performed. The simulation results indicate that superelastic SMA dampers are effective in mitigating the structural response of building structures subjected to strong earthquakes.

  14. Earthquake Vibration Control of Structures using Tuned Liquid Dampers: Experimental Studies

    Directory of Open Access Journals (Sweden)

    Pradipta Banerji


    Full Text Available Earlier studies have shown conclusively that a Tuned Liquid Damper (TLD is effective for controlling vibrations in structures subjected to narrow-banded wind excitations. A recent numerical study has shown that if the design parameters of a TLD are properly set, this device could also be very effective for controlling structural vibration to broad-banded earthquake excitations. Here the results of a reasonably comprehensive set of experiments are presented to investigate the overall effectiveness of TLDs and the specific effect of TLD parameters (depth and mass ratios for earthquake vibration control of structures. Effects of various earthquake ground motions parameters such as amplitude, frequency content, duration of excitation etc. are also evaluated. It is shown that there is good agreement between the numerical simulation and experimental results. This experimental study conclusively shows that a properly designed TLD reduces structural response to broad-band earthquake excitations. It is also observed that effectiveness of TLD increases with increase in mass ratio, depth ratio and amplitude of ground motion.

  15. Vibration Control of Flexible Mode for a Beam-Type Substrate Transport Robot

    Directory of Open Access Journals (Sweden)

    Cheol Hoon Park


    Full Text Available Beam-type substrate transport robots are widely used to handle substrates, especially in the solar cell manufacturing process. To reduce the takt time and increase productivity, accurate position control becomes increasingly important as the size of the substrate increases. However, the vibration caused by the flexible forks in beam-type robots interferes with accurate positioning, which results in long takt times in the manufacturing process. To minimize the vibration and transport substrates on the fork as fast as possible, the trajectories should be prevented from exciting the flexible modes of the forks. For this purpose, a fifth-order polynomial trajectory generator and input shaping were incorporated into the controller of the beam-type robot in this study. The flexible modes of the forks were identified by measuring the frequency response function (FRF, and the input shaping was designed so as not to excite the flexible modes. The controller was implemented by using MATLAB/xPC Target. In this paper, the design procedure of input shaping and its effectiveness for vibration attenuation in both “no load” and “load” cases is presented.

  16. Active Vibration Control of a Nonlinear Beam with Self- and External Excitations

    Directory of Open Access Journals (Sweden)

    J. Warminski


    Full Text Available An application of the nonlinear saturation control (NSC algorithm for a self-excited strongly nonlinear beam structure driven by an external force is presented in the paper. The mathematical model accounts for an Euler-Bernoulli beam with nonlinear curvature, reduced to first mode oscillations. It is assumed that the beam vibrates in the presence of a harmonic excitation close to the first natural frequency of the beam, and additionally the beam is self-excited by fluid flow, which is modelled by a nonlinear Rayleigh term for self-excitation. The self- and externally excited vibrations have been reduced by the application of an active, saturation-based controller. The approximate analytical solutions for a full structure have been found by the multiple time scales method, up to the first-order approximation. The analytical solutions have been compared with numerical results obtained from direct integration of the ordinary differential equations of motion. Finally, the influence of a negative damping term and the controller's parameters for effective vibrations suppression are presented.

  17. Ultrafast Control of the electronic phase of a manganite viamode-selective vibrational excitation

    Energy Technology Data Exchange (ETDEWEB)

    Rini, Matteo; Tobey, Ra' anan I.; Dean, Nicky; Tokura, Yoshinori; Schoenlein, Robert W.; Cavalleri, Andrea


    Controlling a phase of matter by coherently manipulatingspecific vibrational modes has long been an attractive (yet elusive) goalfor ultrafast science. Solids with strongly correlated electrons, inwhich even subtle crystallographic distortions can result in colossalchanges of the electronic and magnetic properties, could be directedbetween competing phases by such selective vibrational excitation. Inthis way, the dynamics of the electronic ground state of the systembecome accessible, and new insight into the underlying physics might begained. Here we report the ultrafast switching of the electronic phase ofa magnetoresistive manganite via direct excitation of a phonon mode at 71meV (17 THz). A prompt, five-order-of-magnitude drop in resistivity isobserved, associated with a non-equilibrium transition from the stableinsulating phase to a metastable metallic phase. In contrast withlight-induced, and current-driven phase transitions, the vibrationallydriven bandgap collapse observed here is not related to hot-carrierinjection and is uniquely attributed to a large-amplitude Mn-Odistortion. This corresponds to a perturbation of theperovskite-structure tolerance factor, which in turn controls theelectronic bandwidth via inter-site orbital overlap. Phase control bycoherent manipulation of selected metal--oxygen phonons should findextensive application in other complex solids--notably in copper oxidesuperconductors, in which the role of Cu-O vibrations on the electronicproperties is currently controversial.

  18. Adaptive active control of structural vibration by minimisation of total supplied power

    DEFF Research Database (Denmark)

    Henriksen, Eigil


    Active control of vibration by minimisation of total supplied power is an attractive approach from a theoretical point of view. In this practical study of the method two secondary sources were applied to control the sinusoidal excitation of an aluminium beam from a single primary source....... The control algorithm was able to reduce the total supplied source power in a frequency band ranging from 50 to 500 Hz. The algorithm is surprisingly insensitive to measurement errors. However, very precise estimates of the power from the individual sources are required to quantify the total supplied power....

  19. The control of drilling vibrations: A coupled PDE-ODE modeling approach

    Directory of Open Access Journals (Sweden)

    Saldivar Belem


    Full Text Available The main purpose of this contribution is the control of both torsional and axial vibrations occurring along a rotary oilwell drilling system. The model considered consists of a wave equation coupled to an ordinary differential equation (ODE through a nonlinear function describing the rock-bit interaction. We propose a systematic method to design feedback controllers guaranteeing ultimate boundedness of the system trajectories and leading consequently to the suppression of harmful dynamics. The proposal of a Lyapunov-Krasovskii functional provides stability conditions stated in terms of the solution of a set of linear and bilinear matrix inequalities (LMIs, BMIs. Numerical simulations illustrate the efficiency of the obtained control laws.

  20. Whole-body vibration versus proprioceptive training on postural control in post-menopausal osteopenic women. (United States)

    Stolzenberg, Nils; Belavý, Daniel L; Rawer, Rainer; Felsenberg, Dieter


    To prevent falls in the elderly, especially those with low bone density, is it necessary to maintain muscle coordination and balance. The aim of this study was to examine the effect of classical balance training (BAL) and whole-body vibration training (VIB) on postural control in post-menopausal women with low bone density. Sixty-eight subjects began the study and 57 completed the nine-month intervention program. All subjects performed resistive exercise and were randomized to either the BAL- (N=31) or VIB-group (N=26). The BAL-group performed progressive balance and coordination training and the VIB-group underwent, in total, four minutes of vibration (depending on exercise; 24-26Hz and 4-8mm range) on the Galileo Fitness. Every month, the performance of a single leg stance task on a standard unstable surface (Posturomed) was tested. At baseline and end of the study only, single leg stance, Romberg-stance, semi-tandem-stance and tandem-stance were tested on a ground reaction force platform (Leonardo). The velocity of movement on the Posturomed improved by 28.3 (36.1%) (p<0.001) in the VIB-group and 18.5 (31.5%) (p<0.001) in the BAL-group by the end of the nine-month intervention period, but no differences were seen between the two groups (p=0.45). Balance tests performed on the Leonardo device did not show any significantly different responses between the two groups after nine months (p≥0.09). Strength training combined with either proprioceptive training or whole-body vibration was associated with improvements in some, but not all, measures of postural control in post-menopausal women with low bone density. The current study could not provide evidence for a significantly different impact of whole-body vibration or balance training on postural control. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Novel railway-subgrade vibration monitoring technology using phase-sensitive OTDR (United States)

    Wang, Zhaoyong; Lu, Bin; Zheng, Hanrong; Ye, Qing; Pan, Zhengqing; Cai, Haiwen; Qu, Ronghui; Fang, Zujie; Zhao, Howell


    High-speed railway is being developed rapidly; its safety, including infrastructure and train operation, is vital. This paper presents a railway-subgrade vibration monitoring scheme based on phase-sensitive OTDR for railway safety. The subgrade vibration is detected and rebuilt. Multi-dimension comprehensive analysis (MDCA) is proposed to identify the running train signals and illegal constructions along railway. To our best knowledge, it is the first time that a railway-subgrade vibration monitoring scheme is proposed. This scheme is proved effective by field tests for real-time train tracking and activities monitoring along railway. It provides a new passive distributed way for all-weather railway-subgrade vibration monitoring.

  2. Torsional Vibration in the National Wind Technology Center’s 2.5-Megawatt Dynamometer

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha [National Renewable Energy Lab. (NREL), Golden, CO (United States); Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wallen, Robb [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed and generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.

  3. Design and experiment of controlled bistable vortex induced vibration energy harvesting systems operating in chaotic regions (United States)

    Huynh, B. H.; Tjahjowidodo, T.; Zhong, Z.-W.; Wang, Y.; Srikanth, N.


    Vortex induced vibration based energy harvesting systems have gained interests in these recent years due to its potential as a low water current energy source. However, the effectiveness of the system is limited only at a certain water current due to the resonance principle that governs the concept. In order to extend the working range, a bistable spring to support the structure is introduced on the system. The improvement on the performance is essentially dependent on the bistable gap as one of the main parameters of the nonlinear spring. A sufficiently large bistable gap will result in a significant performance improvement. Unfortunately, a large bistable gap might also increase a chance of chaotic responses, which in turn will result in diminutive harvested power. To mitigate the problem, an appropriate control structure is required to stabilize the chaotic vibrations of a VIV energy converter with the bistable supporting structure. Based on the nature of the double-well potential energy in a bistable spring, the ideal control structure will attempt to drive the responses to inter-well periodic vibrations in order to maximize the harvested power. In this paper, the OGY control algorithm is designed and implemented to the system. The control strategy is selected since it requires only a small perturbation in a structural parameter to execute the control effort, thus, minimum power is needed to drive the control input. Facilitated by a wake oscillator model, the bistable VIV system is modelled as a 4-dimensional autonomous continuous-time dynamical system. To implement the controller strategy, the system is discretized at a period estimated from the subspace hyperplane intersecting to the chaotic trajectory, whereas the fixed points that correspond to the desired periodic orbits are estimated by the recurrence method. Simultaneously, the Jacobian and sensitivity matrices are estimated by the least square regression method. Based on the defined fixed point and the

  4. Active Vibration Control of a Large Flexible Manipulator by Inertial Force and Joint Torque. Ph.D. Thesis (United States)

    Lee, Soo Han


    The efficiency and positional accuracy of a lightweight flexible manipulator are limited by its flexural vibrations, which last after a gross motion is completed. The vibration delays subsequent operations. In the proposed work, the vibration is suppressed by inertial force of a small arm in addition to the joint actuators and passive damping treatment. The proposed approach is: (1) Dynamic modeling of a combined system, a large flexible manipulator and a small arm, (2) Determination of optimal sensor location and controller algorithm, and (3) Verification of the fitness of model and the performance of controller.

  5. An overview of smoke control technology (United States)

    Klote, John H.


    Considerable advances in smoke control technology have taken place in the last few decades. However, smoke control is just beginning to take its proper place as a fire protection tool. This paper provides an overview of this technology including discussions of the fundamental principles, stairwell pressurization, zone smoke control, elevator smoke control, system activation, and acceptance testing. In addition, the problems of smoke purging are addressed.

  6. Mathematical Modelling and Parameter Identification of an Electro-Magneto-Mechanical Actuator for Vibration Control

    DEFF Research Database (Denmark)

    Darula, Radoslav; Stein, George Juraj; Kallesøe, Carsten Skovmose


    Electromechanical systems for vibration control exhibit complex non-linear behaviour. Therefore advanced mathematical tools and appropriate simplifications are required for their modelling. To properly understand the dynamics of such a non-linear system, it is necessary to identify the parameters...... of the electromagnetic circuit in its various operational regimes. The parametric identification supplements mathematical derivations. The analyzed mechanical system is essentially a Single Degree-Of-Freedom (SDOF) oscillatory system augmented by magnetic force influence. The additional magnetic force is generated...... by an electromagnet with armature. The electromagnet is energized by a constant voltage source. The SDOF system is excited by a harmonic force causing vibration of the armature. Due to the reluctance variation of the air gap of the magnetic circuit alternating voltage is generated across the coil terminals...

  7. Human hand-transmitted vibration measurements on pedestrian controlled tractor operators by a laser scanning vibrometer. (United States)

    Deboli, R; Miccoli, G; Rossi, G L


    A first application of a new measurement technique to detect vibration transmitted to the human body in working conditions is presented. The technique is based on the use of a laser scanning vibrometer. It was previously developed, analysed and tested using laboratory test benches with electrodynamical exciters, and comparisons with traditional measurement techniques based on accelerometers were made. First, results of tests performed using a real machine generating vibration are illustrated. The machine used is a pedestrian-controlled tractor working in a fixed position. Reference measurements by using the accelerometer have been simultaneously performed while scanning the hand surface by the laser-based measurement system. Results achieved by means of both measurement techniques have been processed, analysed, compared and used to calculate transmissibility maps of the hands of three subjects.

  8. Vibration Control of a Flexible Rotor Using Shape Memory Alloy Wires

    DEFF Research Database (Denmark)

    Alves, Marco Túlio Santana; Enemark, Søren; Steffen Jr, Valdar


    In the present contribution, a theoretical model of a test rig containing a flexible rotor is simulated considering pseudoelastic SMA (Shape Memory Alloy) wires connected to a bearing in order to dissipate energy and consequently reduce vibration. SMAs have characteristics of shape memory...... of rotor and SMA wires are coupled. The chosen constitutive model that governs the SMA behaviour is a modified version of the model by Brinson for the one-dimensional case. Both transient and steady-state tests arenumerically simulated. The first one, a run-up test, is performed only at room temperature....... In the second, the unbalancedrotor runs at the first critical speed and two cases are considered: i) room temperature; ii) time-varying temperature.The results from these evaluations show that SMA can be an interesting alternative for vibration control in rotating machinery....

  9. Simulating Displacement and Velocity Signals by Piezoelectric Sensor in Vibration Control Applications

    Directory of Open Access Journals (Sweden)

    G. J. Sheu


    Full Text Available Intelligent structures with built-in piezoelectric sensor and actuator that can actively change their physical geometry and/or properties have been known preferable in vibration control. However, it is often arguable to determine if measurement of piezoelectric sensor is strain rate, displacement, or velocity signal. This paper presents a neural sensor design to simulate the sensor dynamics. An artificial neural network with error backpropagation algorithm is developed such that the embedded and attached piezoelectric sensor can faithfully measure the displacement and velocity without any signal conditioning circuitry. Experimental verification shows that the neural sensor is effective to vibration suppression of a smart structure by embedded sensor/actuator and a building structure by surface-attached piezoelectric sensor and active mass damper.

  10. Design and Implementation of a Digital Controller for a Vibration Isolation and Vernier Pointing System (United States)

    Neff, Daniel J.; Britcher, Colin P.


    This paper discusses the recommissioning of the Annular Suspension and Pointing System (ASPS), originally developed in the mid 1970's for pointing and vibration isolation of space experiments. The hardware was developed for NASA Langley Research Center by Sperry Flight Systems (now Honeywell Satellite Systems), was delivered to NASA in 1983. Recently, the hardware was loaned to Old Dominion University (ODU). The ASPS includes coarse gimbal assemblies and a Vernier Pointing Assembly (VPA) that utilize magnetic suspension to provide noncontacting vibration isolation and vernier pointing of the payload. The VPA is the main focus of this research. At ODU, the system has been modified such that it can now be operated in a l-g environment without a gravity offload. Suspension of the annular iron rotor in five degrees-of-freedom has been achieved with the use of modern switching power amplifiers and a digital controller implemented on a 486-class PC.

  11. Optimal Vibration Control for Half-Car Suspension on In-Vehicle Networks in Delta Domain

    Directory of Open Access Journals (Sweden)

    Jing Lei


    Full Text Available The paper explores the optimal vibration control design problem for a half-car suspension working on in-vehicle networks in delta domain. First, the original suspension system with ECU-actuator delay and sensor-ECU delay is modeled. By using delta operators, the original system is transformed into an associated sampled-data system with time delays in delta domain. After model transformation, the sampled-data system equation is reduced to one without actuator delays and convenient to calculate the states with nonintegral time delay. Therefore, the sampled-data optimal vibration control law can be easily obtained deriving from a Riccati equation and a Stein equation of delta domain. The feedforward control term and the control memory terms designed in the control law ensure the compensation for the effects produced by disturbance and actuator delay, respectively. Moreover, an observer is constructed to implement the physical realizability of the feedforward term and solve the immeasurability problem of some state variables. A half-car suspension model with delays is applied to simulate the responses through the designed controller. Simulation results illustrate the effectiveness of the proposed controller and the simplicity of the designing approach.

  12. High-damping-performance magnetorheological material for passive or active vibration control (United States)

    Liu, Taixiang; Yang, Ke; Yan, Hongwei; Yuan, Xiaodong; Xu, Yangguang


    Optical assembly and alignment system plays a crucial role for the construction of high-power or high-energy laser facility, which attempts to ignite fusion reaction and go further to make fusion energy usable. In the optical assembly and alignment system, the vibration control is a key problem needs to be well handled and a material with higher damping performance is much desirable. Recently, a new kind of smart magneto-sensitive polymeric composite material, named magnetorheological plastomer (MRP), was synthesized and reported as a high-performance magnetorheological material and this material has a magneto-enhanced high-damping performance. The MRP behaves usually in an intermediate state between fluid-like magnetorheological fluid and solid-like magnetorheological elastomer. The state of MRP, as well as the damping performance of MRP, can be tuned by adjusting the ratio of hard segments and soft segments, which are ingredients to synthesize the polymeric matrix. In this work, a series of MRP are prepared by dispersing micron-sized, magneto-sensitive carbonyl iron powders with related additives into polyurethane-based, magnetically insensitive matrix. It is found that the damping performance of MRP depends much on magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. Especially, the damping capacity of MRP can be tuned in a large range by adjusting external magnetic field. It is promising that the MRP will have much application in passive and active vibration control, such as vibration reduction in optical assembly and alignment system, vibration isolation or absorption in vehicle suspension system, etc.

  13. Investigation of an energy harvesting MR damper in a vibration control system (United States)

    Sapiński, Bogdan; Rosół, Maciej; Węgrzynowski, Marcin


    In this paper the authors investigate the performance of an energy harvesting MR damper (EH-MRD) employed in a semi-active vibration control system (SVCS) and used in a single DOF mechanical structure configuration. Main components of the newly proposed SCVS include the MR damper and an electromagnetic vibration energy harvester based on the Faraday’s law (EVEH) that converts vibration energy into electrical energy and delivers electrical power supplying the MR damper. The main objective of the study is to indicate that the SVCS, controlled by the specially designed embedded system, is feasible and presents good performance at the present stage of the research. The work describes investigation the unique features of the EH-MRD, i.e. its self-powering and self-sensing capabilities. Two cases were considered and the testing was done accordingly. In the case 1, only the self-powered capability was investigated. It was found out that harvested energy is sufficient to power the EH-MRD damper and to adjust it to structural vibration. The results confirmed the adequacy of the SVCS and demonstrated a significant reduction of the resonance peak. In the case 2, both the self-powering and self-sensing capabilities were investigated. Due to the self-sensing capability, the SCVS does not require any sensor. It appeared that thus harvested energy is sufficient to power the EH-MRD and enables self-sensing action since the signal of voltage induced by EVEH agrees with the relative velocity signal across the device. Similar to case 1, the resonance peak is significantly reduced.

  14. The Effects of Tai Chi Chuan Combined with Vibration Training on Balance Control and Lower Extremity Muscle Power (United States)

    Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang


    The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key points Eight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population. The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism. Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other

  15. The effects of tai chi chuan combined with vibration training on balance control and lower extremity muscle power. (United States)

    Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang


    The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key pointsEight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population.The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism.Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other.

  16. A stator flux oriented current vector control of a sensorless 6/4 SRM for reduction of acoustic noise and vibration

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Tzu-Shien [Department of Electrical Engineering, Ming Chi University of Technology, 84 Gungjuan Road, Taishan, Taipei 24301 (China); Liang, Jin-Wei [Department of Mechanical Engineering, Ming Chi University of Technology (China)


    In this paper, a stator flux oriented current vector control of a sensorless three-phase 6/4 switched reluctance motor without position sensors is presented. Space current vector control technology based on torque angle estimation was used to reduce the acoustic noise and vibration of the motor drive system. The power converter for the 6/4 switched reluctance motor is three-phase full bridge inverter. The experimental results show that the maximum level of acoustic noises and vibration are 73 dB and 8 dB; m/s/s, respectively, and the steady speed error of the drive system is less than 0.1% operated at the rated load when the drive system was operated below 1500 rpm. In addition, the transient speed performance is also satisfactory. (author)

  17. Acidic emissions control technology and costs

    Energy Technology Data Exchange (ETDEWEB)

    Emmel, T.E.; Waddell, J.T.; Adams, R.C. (Radian Corp. (US))


    This book describes acidic emissions control technology and costs. The objectives are: to identify and characterize stationary combustion and industrial sources of directly emitted acidic materials in the United States; to evaluate the feasibility of control technologies for these sources; and to estimate the costs of applying these control technologies. This book gives results of estimates, using a model plant approach, of costs for retrofitting selected acidic emission control systems to utility and industrial boilers, Claus sulfur recovery plants, catalytic cracking units, primary copper smelters, coke oven plants, primary aluminum smelters, and municipal solid waste incinerators.

  18. Model-free fuzzy control of a magnetorheological elastomer vibration isolation system: analysis and experimental evaluation (United States)

    Fu, Jie; Li, Peidong; Wang, Yuan; Liao, Guanyao; Yu, Miao


    This paper addresses the problem of micro-vibration control of a precision vibration isolation system with a magnetorheological elastomer (MRE) isolator and fuzzy control strategy. Firstly, a polyurethane matrix MRE isolator working in the shear-compression mixed mode is introduced. The dynamic characteristic is experimentally tested, and the range of the frequency shift and the model parameters of the MRE isolator are obtained from experimental results. Secondly, a new semi-active control law is proposed, which uses isolation structure displacement and relative displacement between the isolation structure and base as the inputs. Considering the nonlinearity of the MRE isolator and the excitation uncertainty of an isolation system, the designed semi-active fuzzy logic controller (FLC) is independent of a system model and is robust. Finally, the numerical simulations and experiments are conducted to evaluate the performance of the FLC with single-frequency and multiple-frequency excitation, respectively, and the experimental results show that the acceleration transmissibility is reduced by 54.04% at most, which verifies the effectiveness of the designed semi-active FLC. Moreover, the advantages of the approach are demonstrated in comparison to the passive control and ON-OFF control.

  19. Vibration Control of Double-Beam System with Multiple Smart Damping Members

    Directory of Open Access Journals (Sweden)

    Dominik Pisarski


    Full Text Available A control method to stabilize vibration of a double cantilever system with a set of smart damping blocks is designed and numerically evaluated. The externally controlled magnetorheological sheared elastomer damping block is considered, but other smart materials can be used as well. The robust bang-bang control law for stabilization the bilinear system is elaborated. The key feature of the closed loop controller is the efficiency for different types of initial excitement. By employing the finite element model, the performance of the controller is validated for strong wind blow load and concentrated impact excitement of the particular point of one of the beams. For each of the excitations, the closed loop control outperforms the optimal passive damping case by over 27% for the considered energy metric.

  20. Reduced plantar sole sensitivity induces balance control modifications to compensate ankle tendon vibration and vision deprivation. (United States)

    Billot, Maxime; Handrigan, Grant A; Simoneau, Martin; Teasdale, Normand


    The aim of this study was to investigate if sensory reweighting occurred to control balance when the sensitivity of the plantar sole is reduced using cooling. To address this question, visual information was manipulated and/or ankle proprioception was altered by Achilles tendon vibration. It was expected that Achilles tendon vibration and vision deprivation would induce greater center of pressure (CoP) excursions and/or increase of electromyographic (EMG) activity of the ankle muscles (triceps surea and tibialis anterior) with than without cooling of the plantar sole. To verify these hypotheses, the CoP and EMG activity of the ankle muscles were simultaneously recorded during quiet standing trials of 30s before and after feet cooling procedure. Results showed that plantar sole sensitivity alteration did not lead to larger CoP excursions even during Achilles tendon vibration in absence of vision. This could be explained by an increase in the EMG activity of the triceps surae after the cooling procedure without modification of tibialis anterior EMG activity. This study suggests that to compensate alteration in plantar sole sensitivity, the central nervous system increased the muscular activity of the triceps surae to limit CoP excursions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Mastoid vibration affects dynamic postural control during gait in healthy older adults (United States)

    Chien, Jung Hung; Mukherjee, Mukul; Kent, Jenny; Stergiou, Nicholas


    Vestibular disorders are difficult to diagnose early due to the lack of a systematic assessment. Our previous work has developed a reliable experimental design and the result shows promising results that vestibular sensory input while walking could be affected through mastoid vibration (MV) and changes are in the direction of motion. In the present paper, we wanted to extend this work to older adults and investigate how manipulating sensory input through mastoid vibration (MV) could affect dynamic postural control during walking. Three levels of MV (none, unilateral, and bilateral) applied via vibrating elements placed on the mastoid processes were combined with the Locomotor Sensory Organization Test (LSOT) paradigm to challenge the visual and somatosensory systems. We hypothesized that the MV would affect sway variability during walking in older adults. Our results revealed that MV significantly not only increased the amount of sway variability but also decreased the temporal structure of sway variability only in anterior-posterior direction. Importantly, the bilateral MV stimulation generally produced larger effects than the unilateral. This is an important finding that confirmed our experimental design and the results produced could guide a more reliable screening of vestibular system deterioration.

  2. Simulations and Experiments on Vibration Control of Aerospace Thin-Walled Parts via Preload

    Directory of Open Access Journals (Sweden)

    Qiong Wu


    Full Text Available Thin-walled parts primarily comprise the entire piece of rough machining, and the material removal rate can surpass 95%. Numerous components with thin-walled structures are preferred in the aerospace industry for their light weight, high strength, and other advantages. In aerospace thin-walled workpiece machining processes and practical applications, they are excited by the vibration. The preload changing the modal stiffness of the part is found and this change causes continuous changes in the natural frequency. Researching on the influence of pretightening force on dynamic characteristics of thin-walled components is highly significant for controlling vibration. In this study, the typical aviation thin-walled part is the research object. Finite element numerical simulation and experimental verification are employed to analyze the dynamic characteristics of 7075 aluminum alloy thin-walled plates under different preloads for exploring the relationship between natural frequency and preload. The relationship is validated by comparative results. Both the simulation and experimental results show that the natural frequencies of plates increase following the augmentation of the preload. Thus, this research introduces the method where vibration of aerospace thin-walled parts is reduced by preload. For practical engineering application, a program showing the relationship between natural frequency and preload is written using Visual Basic language.

  3. Application of system concept in vibration and noise reduction

    Directory of Open Access Journals (Sweden)

    SHENG Meiping


    Full Text Available Although certain vibration and noise control technologies are maturing, such as vibration absorption, vibration isolation, sound absorption and sound insulation, and new methods for specific frequency bands or special environments have been proposed unceasingly, there is still no guarantee that practical effective vibration and noise reduction can be obtained. An important constraint for vibration and noise reduction is the lack of a system concept, and the integrity and relevance of such practical systems as ship structure have not obtained enough attention. We have tried to use the system engineering theory in guiding vibration and noise reduction, and have already achieved certain effects. Based on the system concept, the noise control of a petroleum pipeline production workshop has been completed satisfactorily, and the abnormal noise source identification of an airplane has been accomplished successfully. We want to share our experience and suggestions to promote the popularization of the system engineering theory in vibration and noise control.

  4. Seismic Vibration Control of 3D Steel Frames with Irregular Plans Using Eccentrically Placed MR Dampers

    Directory of Open Access Journals (Sweden)

    Yuwen Hu


    Full Text Available There has been a significant increase in attention toward designing smart structures and vibration control of structures in recent decades, and numerous methods and algorithms have been developed and experimentally investigated. However, the majority of these studies used the shear frame models to represent structures. Since the simplified models do not reflect the realistic behavior of those structures with irregularity in plan and elevation, the traditional methods for designing an optimal control that guarantees a desirable performance is impossible. In this study, the behavior of a 10-story irregular steel frame building is investigated with and without controlling systems. Two pairs of eccentrically placed MR dampers on each story are used in order to mitigate the coupled translational–torsional vibration. The controlling forces are determined using active, passive-off, passive-on, and clipped optimal controls based on the linear quadratic regulator (LQR algorithm. The results demonstrate that using pairs of magneto-rheological (MR dampers with an appropriate distance on lower story levels significantly reduces the inter-story drifts for the corner columns, as well as the roof displacements and accelerations.

  5. Vibration Control by a Shear Type Semi-active Damper Using Magnetorheological Grease (United States)

    Shiraishi, Toshihiko; Misaki, Hirotaka


    This paper describes semi-active vibration control by a controllable damper with high reliability and wide dynamic range using magnetorheological (MR) grease. Some types of cylindrical controllable dampers based on pressure difference between chambers in the dampers using “MR fluid”, whose rheological properties can be varied by applying a magnetic field, have been reported as a semi-active device. However, there are some challenging issues of them. One is to improve dispersion stability. The particles dispersed in MR fluid would make sedimentation after a period. Another is to expand dynamic range. Since cylindrical dampers require sealing elements because of pressure difference in the dampers, the dynamic range between the maximum and minimum damping force according to a magnetic field is reduced. In this study, a controllable damper using the MR effect was proposed and its performance was experimentally verified to improve the dispersion stability by using “MR grease”, which includes grease as the carrier of magnetic particles, and to expand the dynamic range by adopting a shear type structure not requiring sealing elements. Furthermore, semiactive vibration control experiments by the MR grease damper using a simple algorithm based on the skyhook damper scheme were conducted and its performance was investigated.

  6. Adaptive filtering and feed-forward control for suppression of vibration and jitter (United States)

    Anderson, Eric H.; Blankinship, Ross L.; Fowler, Leslie P.; Glaese, Roger M.; Janzen, Paul C.


    This paper describes the use of adaptive filtering to control vibration and optical jitter. Adaptive filtering is a class of signal processing techniques developed over the last several decades and applied since to applications ranging from communications to image processing. Basic concepts in adaptive filtering and feedforward control are reviewed. A series of examples in vibration, motion and jitter control, including cryocoolers, ground-based active optics systems, flight motion simulators, wind turbines and airborne optical beam control systems, illustrates the effectiveness of the adaptive methods. These applications make use of information and signals that originate from system disturbances and minimize the correlations between disturbance information and error and performance measures. The examples incorporate a variety of disturbance types including periodic, multi-tonal, broadband stationary and non-stationary. Control effectiveness with slowly-varying narrowband disturbances originating from cryocoolers can be extraordinary, reaching 60 dB of reduction or rejection. In other cases, performance improvements are only 30-50%, but such reductions effectively complement feedback servo performance in many applications.

  7. Thermal Effects on Vibration and Control of Piezocomposite Kirchhoff Plate Modeled by Finite Elements Method

    Directory of Open Access Journals (Sweden)

    M. Sanbi


    Full Text Available Theoretical and numerical results of the modeling of a smart plate are presented for optimal active vibration control. The smart plate consists of a rectangular aluminum piezocomposite plate modeled in cantilever configuration with surface bonded thermopiezoelectric patches. The patches are symmetrically bonded on top and bottom surfaces. A generic thermopiezoelastic theory for piezocomposite plate is derived, using linear thermopiezoelastic theory and Kirchhoff assumptions. Finite element equations for the thermopiezoelastic medium are obtained by using the linear constitutive equations in Hamilton’s principle together with the finite element approximations. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG-Kalman filter is applied. By using this model, the study first gives the influences of the actuator/sensor pair placement and size on the response of the smart plate. Second, the effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. It is shown that the effectiveness of the control is not affected by the applied thermal gradient and can be applied with or without this gradient at any time of plate vibrations.

  8. MIMO active vibration control of magnetically suspended flywheels for satellite IPAC service (United States)

    Park, Junyoung

    Theory and simulation results have demonstrated that four, variable speed flywheels could potentially provide the energy storage and attitude control functions of existing batteries and control moment gyros (CMGs) on a satellite. Past modeling and control algorithms were based on the assumption of rigidity in the flywheel's bearings and the satellite structure. This dissertation provides simulation results and theory which eliminates this assumption utilizing control algorithms for active vibration control (AVC), flywheel shaft levitation and integrated power transfer and attitude control (IPAC) that are effective even with low stiffness active magnetic bearings (AMB), and flexible satellite appendages. The flywheel AVC and levitation tasks are provided by a multi input multi output (MIMO) control law that enhances stability by reducing the dependence of the forward and backward gyroscopic poles with changes in flywheel speed. The control law is shown to be effective even for (1) Large polar to transverse inertia ratios which increases the stored energy density while causing the poles to become more speed dependent and, (2) Low bandwidth controllers shaped to suppress high frequency noise. These two main tasks could be successfully achieved by MIMO (Gyroscopic) control algorithm, which is unique approach. The vibration control mass (VCM) is designed to reduce the vibrations of flexible appendages of the satellite. During IPAC maneuver, the oscillation of flywheel spin speeds, torque motions and satellite appendages are significantly reduced compared without VCM. Several different properties are demonstrated to obtain optimal VCM. Notch, band-pass and low-pass filters are implemented in the AMB system to reduce and cancel high frequency, dynamic bearing forces and motor torques due to flywheel mass imbalance. The transmitted forces and torques to satellite are considerably decreased in the present of both notch and band-pass filter stages. Successful IPAC simulation

  9. Active control of sound transmission/radiation from elastic plates by vibration inputs. I - Analysis (United States)

    Fuller, C. R.


    Active control of sound radiation from vibrating plates by oscillating forces applied directly to the structure is analytically studied. The model consists of a plane acoustic wave incident on a clamped elastic circular thin plate. Control is achieved by point forces, and quadratic optimization is used to calculate the optimal control gains necessary to minimize a cost function proportional to the radiated acoustic power (the transmitted field). The results show that global attenuation of broadband radiated sound levels for low to mid-range frequencies can be achieved with one or two control forces, irrespective of whether the system is on or off resonance. The efficiency of the control strategy is demonstrated to be related to the nature of the coupling between the plate modes of response and the radiated field.

  10. Reduction of Helicopter BVI Noise, Vibration, and Power Consumption Through Individual Blade Control (United States)

    Jacklin, Stephen A.; Blaas, Achim; Teves, Dietrich; Kube, Roland; Warmbrodt, William (Technical Monitor)


    A wind tunnel test was conducted with a full-scale BO 105 helicopter rotor to evaluate the potential of open-loop individual blade control (IBC) to improve rotor performance, to reduce blade vortex interaction (BVI) noise, and to alleviate helicopter vibrations. The wind tunnel test was an international collaborative effort between NASA/U.S. Army AFDD, ZF Luftfahrttechnik, Eurocopter Deutschland, and the German Aerospace Laboratory (DLR) and was conducted under the auspices of the U.S./German MOU on Rotorcraft Aeromechanics. In this test the normal blade pitch links of the rotor were replaced by servo-actuators so that the pitch of each blade could be controlled independently of the other blades. The specially designed servoactuators and IBC control system were designed and manufactured by ZF Luftfahrttechnik, GmbH. The wind tunnel test was conducted in the 40- by 80-Foot Wind Tunnel at the NASA Ames Research Center. An extensive amount of measurement information was acquired for each IBC data point. These data include rotor performance, static and dynamic hub forces and moments, rotor loads, control loads, inboard and outboard blade pitch motion, and BVI noise data. The data indicated very significant (80 percent) simultaneous reductions in both BVI noise and hub vibrations could be obtained using multi-harmonic input at the critical descent (terminal approach) condition. The data also showed that performance improvements of up to 7 percent could be obtained using 2P input at high-speed forward flight conditions.

  11. Torsional Vibration Semiactive Control of Drivetrain Based on Magnetorheological Fluid Dual Mass Flywheel

    Directory of Open Access Journals (Sweden)

    Qing-hua Zu


    Full Text Available The damping characteristics of the traditional dual mass flywheel (DMF cannot be changed and can only meet one of the damping requirements. Given that the traditional DMF cannot avoid the resonance interval in start/stop conditions, it tends to generate high-resonance amplitude, which reduces the lifetime of a vehicle’s parts and leads to vehicle vibration and noise. The problems associated with the traditional DMF can be solved through the magnetorheological fluid dual mass flywheel (MRF-DMF, which was designed in this study with adjustable damping performance under different conditions. The MRF-DMF is designed based on the rheological behavior of the magnetorheological fluid (MRF, which can be changed by magnetic field strength. The damping torque of the MRF-DMF, which is generated by the MRF effect, is derived in detail. Thus, the cosimulation between the drivetrain model built in AMESim and the control system model developed in Simulink is conducted. The controller of MRF-DMF is developed, after which the torsional vibration control test of drivetrain is carried out. The cosimulation and test results indicate that MRF-DMF with the controller effectively isolates torque fluctuation of the engine in the driving condition and exhibits high performance in suppressing the resonance amplitude in the start/stop conditions.

  12. An Experimental Validated Control Strategy of Maglev Vehicle-Bridge Self-Excited Vibration

    Directory of Open Access Journals (Sweden)

    Lianchun Wang


    Full Text Available This study discusses an experimentally validated control strategy of maglev vehicle-bridge vibration, which degrades the stability of the suspension control, deteriorates the ride comfort, and limits the cost of the magnetic levitation system. First, a comparison between the current-loop and magnetic flux feedback is carried out and a minimum model including flexible bridge and electromagnetic levitation system is proposed. Then, advantages and disadvantages of the traditional feedback architecture with the displacement feedback of electromagnet yE and bridge yB in pairs are explored. The results indicate that removing the feedback of the bridge’s displacement yB from the pairs (yE − yB measured by the eddy-current sensor is beneficial for the passivity of the levitation system and the control of the self-excited vibration. In this situation, the signal acquisition of the electromagnet’s displacement yE is discussed for the engineering application. Finally, to validate the effectiveness of the aforementioned control strategy, numerical validations are carried out and the experimental data are provided and analyzed.

  13. Vibration, buckling and smart control of microtubules using piezoelectric nanoshells under electric voltage in thermal environment

    Energy Technology Data Exchange (ETDEWEB)

    Farajpour, A., E-mail:; Rastgoo, A.; Mohammadi, M.


    Piezoelectric nanomaterials such as zinc oxide (ZnO) are of low toxicity and have many biomedical applications including optical imaging, drug delivery, biosensing and harvesting biomechanical energy using hybrid nanogenerators. In this paper, the vibration, buckling and smart control of microtubules (MTs) embedded in an elastic medium in thermal environment using a piezoelectric nanoshell (PNS) are investigated. The MT and PNS are considered to be coupled by a filament network. The PNS is subjected to thermal loads and an external electric voltage which operates to control the mechanical behavior of the MT. Using the nonlocal continuum mechanics, the governing differential equations are derived. An exact solution is presented for simply supported boundary conditions. The differential quadrature method is also used to solve the governing equations for other boundary conditions. A detailed parametric study is conducted to investigate the effects of the elastic constants of surrounding medium and internal filament matrix, scale coefficient, electric voltage, the radius-to-thickness ratio of PNSs and temperature change on the smart control of MTs. It is found that the applied electric voltage can be used as an effective controlling parameter for the vibration and buckling of MTs.

  14. Vibration, buckling and smart control of microtubules using piezoelectric nanoshells under electric voltage in thermal environment (United States)

    Farajpour, A.; Rastgoo, A.; Mohammadi, M.


    Piezoelectric nanomaterials such as zinc oxide (ZnO) are of low toxicity and have many biomedical applications including optical imaging, drug delivery, biosensing and harvesting biomechanical energy using hybrid nanogenerators. In this paper, the vibration, buckling and smart control of microtubules (MTs) embedded in an elastic medium in thermal environment using a piezoelectric nanoshell (PNS) are investigated. The MT and PNS are considered to be coupled by a filament network. The PNS is subjected to thermal loads and an external electric voltage which operates to control the mechanical behavior of the MT. Using the nonlocal continuum mechanics, the governing differential equations are derived. An exact solution is presented for simply supported boundary conditions. The differential quadrature method is also used to solve the governing equations for other boundary conditions. A detailed parametric study is conducted to investigate the effects of the elastic constants of surrounding medium and internal filament matrix, scale coefficient, electric voltage, the radius-to-thickness ratio of PNSs and temperature change on the smart control of MTs. It is found that the applied electric voltage can be used as an effective controlling parameter for the vibration and buckling of MTs.

  15. Active Vibration Control of a Microactuator for the Hard Disk Drive Using Self-Sensing Actuation

    Directory of Open Access Journals (Sweden)

    Minoru Sasaki


    Full Text Available This paper presents the self-sensing control of a microactuator for hard disk drives. The microactuator uses a PZT actuator pair installed on the suspension assembly. The self-sensing microactuator forms a combined sensing and actuation mechanism. Direct velocity feedback and positive position feedback are used in this paper. Our experimental results show that both strategies are effective in suppressing vibrational modes and successfully demonstrate the feasibility of using a self-sensing actuator on an HDD suspension assembly.

  16. Uncertainty modeling in vibration, control and fuzzy analysis of structural systems

    CERN Document Server

    Halder, Achintya; Ayyub, Bilal M


    This book gives an overview of the current state of uncertainty modeling in vibration, control, and fuzzy analysis of structural and mechanical systems. It is a coherent compendium written by leading experts and offers the reader a sampling of exciting research areas in several fast-growing branches in this field. Uncertainty modeling and analysis are becoming an integral part of system definition and modeling in many fields. The book consists of ten chapters that report the work of researchers, scientists and engineers on theoretical developments and diversified applications in engineering sy

  17. Vibration control of a flexible rotor on variable parameter squeeze film damper (United States)

    Wang, Chuanfa; Zhang, Azhou; Huang, Taiping


    In this paper, the effectiveness of VPSFD (Variable Parameter Squeeze Film Damper) parameter change on control of resonant amplitude of a simple rotor system, which has one disk at the center of the span on one squirrel-cage elastic bearing with VPSFD, is investigated. On the basis of steady state tests, the vibration suppression of the rotor through the first two critical speeds has been done. The results show that the first two resonant amplitudes will be greatly decreased and the rotor system will run smoothly through the first two critical speeds.

  18. Dynamics and Control of Lateral Tower Vibrations in Offshore Wind Turbines by Means of Active Generator Torque

    Directory of Open Access Journals (Sweden)

    Zili Zhang


    Full Text Available Lateral tower vibrations of offshore wind turbines are normally lightly damped, and large amplitude vibrations induced by wind and wave loads in this direction may significantly shorten the fatigue life of the tower. This paper proposes the modeling and control of lateral tower vibrations in offshore wind turbines using active generator torque. To implement the active control algorithm, both the mechanical and power electronic aspects have been taken into consideration. A 13-degrees-of-freedom aeroelastic wind turbine model with generator and pitch controllers is derived using the Euler–Lagrangian approach. The model displays important features of wind turbines, such as mixed moving frame and fixed frame-defined degrees-of-freedom, couplings of the tower-blade-drivetrain vibrations, as well as aerodynamic damping present in different modes of motions. The load transfer mechanisms from the drivetrain and the generator to the nacelle are derived, and the interaction between the generator torque and the lateral tower vibration are presented in a generalized manner. A three-dimensional rotational sampled turbulence field is generated and applied to the rotor, and the tower is excited by a first order wave load in the lateral direction. Next, a simple active control algorithm is proposed based on active generator torques with feedback from the measured lateral tower vibrations. A full-scale power converter configuration with a cascaded loop control structure is also introduced to produce the feedback control torque in real time. Numerical simulations have been carried out using data calibrated to the referential 5-MW NREL (National Renewable Energy Laboratory offshore wind turbine. Cases of drivetrains with a gearbox and direct drive to the generator are considered using the same time series for the wave and turbulence loadings. Results show that by using active generator torque control, lateral tower vibrations can be significantly mitigated for


    Discussed are acid rain control options available to the electric utility industry. They include coal switching, flue gas desulfurization, and such emerging lower cost technologies as Limestone Injection Multistage Burners (LIMB) and Advanced Silicate (ADVACATE), both developed ...

  20. Site-specific weed control technologies

    DEFF Research Database (Denmark)

    Christensen, Svend; Søgaard, Henning Tangen; Kudsk, Per


    Site-specific weed control technologies are defined as machinery or equipment embedded with technologies that detect weeds growing in a crop and, taking into account predefined factors such as economics, takes action to maximise the chances of successfully controlling them. In the article, we...... describe the basic parts of site specific weed control technologies, comprising of weed sensing systems, weed management models and precision weed control implements. A review of state-of-the-art technologies shows that several weed sensing systems and precision implements have been developed over the last...... two decades, though barriers prevent their breakthrough. Most important among these is the lack of a truly robust weed recognition method, owing to mutual shading among plants and limitations in the capacity of highly accurate spraying and weeding apparatuses.   Another barrier is the lack...


    Directory of Open Access Journals (Sweden)

    Pao-Hung Chung


    Full Text Available The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV, a Tai Chi Chuan group (TCC or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods.

  2. Good vibrations. [Hydraulic turbines

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, P.


    The latest developments in the Voith Turbine Control and Automation System (VTLS), which couples digital control technology to hydropower plant equipment, are described. Prominent among these is the vibration diagnostics module for hydraulic turbines. It provides machine-specific diagnostic logic for a vibration monitoring and analysis system. Of the two other VTLS modules described, the operation module optimizes the control of a power plant with three or more turbines by considering the individual properties of each in turn, recommending which should be run, and how, in order to partition the load for a required power output. The cavitation module is a diagnostic system which enables the limits of operation of the turbines to be extended to bands just outside those determined by cavitation calculations. (3 figures). (UK)

  3. Vibration control of a cylindrical shell with concurrent active piezoelectric patches and passive cardboard liner (United States)

    Plattenburg, Joseph; Dreyer, Jason T.; Singh, Rajendra


    This article extends a recent publication [MSSP (2016), 176-196] by developing a Rayleigh-Ritz model of a thin cylindrical shell to predict its response subject to concurrent active and passive damping treatments. These take the form of piezoelectric patches and a distributed cardboard liner, since the effects of such combined treatments are yet to be investigated. Furthermore, prior literature typically considers only the ;bimorph; active patch configuration (with patches on the inner and outer shell surfaces), which is not feasible with an interior passive liner treatment. Therefore, a novel configuration-termed as ;unimorph;-is proposed and included in the model. Experiments are performed on a shell with active patches (under harmonic excitation from 200 to 2000 Hz) in both the bimorph and unimorph configurations to provide evidence for the analytical model predictions. The proposed model is then employed to assess competing control system designs by examining local vs. global control schemes as well as considering several alternate active patch locations, both with and without the passive damping. Non-dimensional performance metrics are devised to facilitate comparisons of vibration attenuation among different designs. Finally, insertion loss values are measured under single-frequency excitation to evaluate several vibration control designs, and to compare the effects of alternate damping treatments.

  4. Shape and vibration control of active laminated plates for RF and optical applications (United States)

    Punhani, Amitesh; Washington, Gregory N.


    Active shape and vibration control of large structures have long been desired for many practical applications. PVDF being one of the most suitable materials for these applications due to its strong piezoelectric properties and availability in thin sheets has been the focal point of most researchers in this area. Most of the research has been done to find an open loop solution, which would be able to shape the structure as per the desired requirements in an ideal atmosphere. Unmodeled dynamics and external disturbances prevent the open loop (no feedback) solution from achieving the desired shape. This research develops a dynamic model of a laminated plate consisting of two layers of PVDF film joined with a layer of epoxy. The orthotropic properties of PVDF have been modeled and the epoxy layer is considered to be isotropic. A general control model is developed, which would work for most boundary conditions and developed for a simply supported beam with patch actuators. The methodology is then extended for a simply supported laminated plate. This model could be used for real time dynamic disturbance rejection and shape and vibration control of the structure.

  5. Vibration control of buildings by using partial floor loads as multiple tuned mass

    Directory of Open Access Journals (Sweden)

    Tharwat A. Sakr


    Full Text Available Tuned mass dampers (TMDs are considered as the most common control devices used for protecting high-rise buildings from vibrations. Because of their simplicity and efficiency, they have found wide practical applications in high-rise buildings around the world. This paper proposes an innovative technique for using partial floor loads as multiple TMDs at limited number of floors. This technique eliminates complications resulting from the addition of huge masses required for response control and maintains the mass of the original structure without any added loads. The effects of using partial loads of limited floors starting from the top as TMDs on the vibration response of buildings to wind and earthquakes are investigated. The effects of applying the proposed technique to buildings with different heights and characteristics are also investigated. A parametric study is carried out to illustrate how the behavior of a building is affected by the number of stories and the portion of the floor utilized as TMDs. Results indicate the effectiveness of the proposed control technique in enhancing the drift, acceleration, and force response of buildings to wind and earthquakes. The response of buildings to wind and earthquakes was observed to be more enhanced by increasing the story-mass ratios and the number of floor utilized as TMDs.

  6. Electronic control/display interface technology (United States)

    Parrish, R. V.; Busquets, A. M.; Murray, R. F.; Hatfield, J. J.


    An effort to produce a representative workstation for the Space Station Data Management Test Bed that provides man/machine interface design options for consolidating, automating, and integrating the space station work station, and hardware/software technology demonstrations of space station applications is discussed. The workstation will emphasize the technologies of advanced graphics engines, advanced display/control medias, image management techniques, multifunction controls, and video disk utilizations.

  7. Technology innovations and experience curves for nitrogen oxides control technologies

    Energy Technology Data Exchange (ETDEWEB)

    Sonia Yeh; Edward S. Rubin; Margaret R. Taylor; David A. Hounshell [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Laboratory, Office of Research and Development,


    This paper reviews the regulatory history for nitrogen oxides (NOx) pollutant emissions from stationary sources, primarily in coal-fired power plants. Nitrogen dioxide (NO{sub 2}) is one of the six criteria pollutants regulated by the 1970 Clean Air Act where National Ambient Air Quality Standards were established to protect public health and welfare. Patent data are used to show that in the cases of Japan, Germany, and the United States, innovations in NOx control technologies did not occur until stringent government regulations were in place, thus 'forcing' innovation. It is demonstrated that reductions in the capital and operation and maintenance (O&M) costs of new generations of high-efficiency NOx control technologies, selective catalytic reduction (SCR), are consistently associated with the increasing adoption of the control technology: the so-called learning-by-doing phenomena. The results show that as cumulative world coal-fired SCR capacity doubles, capital costs decline to {approximately} 86% and O&M costs to 58% of their original values. The observed changes in SCR technology reflect the impact of technological advance as well as other factors, such as market competition and economies of scale. 38 refs., 10 figs., 3 tabs.

  8. Vibration reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade (United States)

    Millott, T. A.; Friedmann, P. P.


    This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

  9. Optimal semi-active vibration absorber for harmonic excitation based on controlled semi-active damper (United States)

    Weber, F.


    The semi-active vibration absorber (SVA) based on controlled semi-active damper is formulated to realize the behaviour of the passive undamped vibration absorber tuned to the actual harmonic disturbing frequency. It is shown that the controlled stiffness force, which is emulated by the semi-active damper to realize the precise real-time frequency tuning of the SVA, is unpreventably combined with the generation of undesirable damping in the semi-active damper whereby the SVA does not behave as targeted. The semi-active stiffness force is therefore optimized for minimum primary structure response. The results point out that the optimal semi-active stiffness force reduces the undesirable energy dissipation in the SVA at the expenses of slight imprecise frequency tuning. Based on these findings, a real-time applicable suboptimal SVA is formulated that also takes the relative motion constraint of real mass dampers into account. The results demonstrate that the performance of the suboptimal SVA is closer to that of the active solution than that of the passive mass damper.

  10. Wind-Induced Vibration Control of Dalian International Trade Mansion by Tuned Liquid Dampers

    Directory of Open Access Journals (Sweden)

    Hong-Nan Li


    Full Text Available This paper focuses on the wind-induced vibration control of the Dalian international trade mansion (DITM by using the tuned liquid dampers (TLDs. To avoid the intensive computationally demanding problem caused by tens of thousand of degrees of freedom (DOF of the structure in the numerical analysis, the three-dimension finite element model of the DITM is first simplified to the equivalent series multi-DOF system. The wind loading is subsequently simulated by the Davenport model according to the structural environmental condition where the actual samples of wind speed are measured. Following that, the shallow- and deep-water wave theories are applied to model the liquid sloshing inside TLDs, the tank sizing, and required water depth, and numbers of TLDs are given according to the numerical results of different cases. Comparisons between uncontrolled and controlled displacement and acceleration responses of the DITM under wind forces show that the designed shallow tank has higher efficiency than the deep one, which can effectively reduce the structural response amplitudes and enhance the comfortableness of the mansion. The preliminary TLD design procedure presented in this paper could be applied as a reference to the analysis and design of the wind-induced vibration for high-rise buildings using the TLD.

  11. Can Internal Conversion BE Controlled by Mode-Specific Vibrational Excitation in Polyatomic Molecules (United States)

    Portnov, Alexander; Epshtein, Michael; Bar, Ilana


    Nonadiabatic processes, dominated by dynamic passage of reactive fluxes through conical intersections (CIs) are considered to be appealing means for manipulating reaction paths. One approach that is considered to be effective in controlling the course of dissociation processes is the selective excitation of vibrational modes containing a considerable component of motion. Here, we have chosen to study the predissociation of the model test molecule, methylamine and its deuterated isotopologues, excited to well-characterized quantum states on the first excited electronic state, S_{1}, by following the N-H(D) bond fission dynamics through sensitive H(D) photofragment probing. The branching ratios between slow and fast H(D) photofragments, the internal energies of their counter radical photofragments and the anisotropy parameters for fast H photofragments, confirm correlated anomalies for predissociation initiated from specific rovibronic states, reflecting the existence of a dynamic resonance in each molecule. This resonance strongly depends on the energy of the initially excited rovibronic states, the evolving vibrational mode on the repulsive S_{1} part during N-H(D) bond elongation, and the manipulated passage through the CI that leads to radicals excited with C-N-H(D) bending and preferential perpendicular bond breaking, relative to the photolyzing laser polarization, in molecules containing the NH_{2} group. The indicated resonance plays an important role in the bifurcation dynamics at the CI and can be foreseen to exist in other photoinitiated processes and to control their outcome.

  12. Integration Design and Optimization Control of a Dynamic Vibration Absorber for Electric Wheels with In-Wheel Motor

    Directory of Open Access Journals (Sweden)

    Mingchun Liu


    Full Text Available This paper presents an integration design scheme and an optimization control strategy for electric wheels to suppress the in-wheel vibration and improve vehicle ride comfort. The in-wheel motor is considered as a dynamic vibration absorber (DVA, which is isolated from the unsprung mass by using a spring and a damper. The proposed DVA system is applicable for both the inner-rotor motor and outer-rotor motor. Parameters of the DVA system are optimized for the typical conditions, by using the particle swarm optimization (PSO algorithm, to achieve an acceptable vibration performance. Further, the DVA actuator force is controlled by using the alterable-domain-based fuzzy control method, to adaptively suppress the wheel vibration and reduce the wallop acting on the in-wheel motor (IWM as well. In addition, a suspension actuator force is also controlled, by using the linear quadratic regulator (LQR method, to enhance the suspension performance and meanwhile improve vehicle ride comfort. Simulation results demonstrate that the proposed DVA system effectively suppresses the wheel vibration and simultaneously reduces the wallop acting on the IWM. Also, the alterable-domain-based fuzzy control method performs better than the conventional ones, and the LQR-based suspension exhibits excellent performance in vehicle ride comfort.

  13. Structural Health Monitoring Using Wireless Technologies: An Ambient Vibration Test on the Adolphe Bridge, Luxembourg City

    Directory of Open Access Journals (Sweden)

    Adrien Oth


    Full Text Available Major threats to bridges primarily consist of the aging of the structural elements, earthquake-induced shaking and standing waves generated by windstorms. The necessity of information on the state of health of structures in real-time, allowing for timely warnings in the case of damaging events, requires structural health monitoring (SHM systems that allow the risks of these threats to be mitigated. Here we present the results of a short-duration experiment carried out with low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of a strategic civil infrastructure, the Adolphe Bridge in Luxembourg City. The Adolphe Bridge is a masonry arch construction dating from 1903 and will undergo major renovation works in the upcoming years. Our experiment shows that a network of these wireless sensing units is well suited to monitor the vibration characteristics of such a historical arch bridge and hence represents a low-cost and efficient solution for SHM.

  14. Self-tuning pressure-feedback control by pole placement for vibration reduction of excavator with independent metering fluid power system (United States)

    Ding, Ruqi; Xu, Bing; Zhang, Junhui; Cheng, Min


    Independent metering control systems are promising fluid power technologies compared with traditional valve controlled systems. By breaking the mechanical coupling between the inlet and outlet, the meter-out valve can open as large as possible to reduce energy consumptions. However, the lack of damping in outlet causes stronger vibrations. To address the problem, the paper designs a hybrid control method combining dynamic pressure-feedback and active damping control. The innovation resides in the optimization of damping by introducing pressure feedback to make trade-offs between high stability and fast response. To achieve this goal, the dynamic response pertaining to the control parameters consisting of feedback gain and cut-off frequency, are analyzed via pole-zero locations. Accordingly, these parameters are tuned online in terms of guaranteed dominant pole placement such that the optimal damping can be accurately captured under a considerable variation of operating conditions. The experiment is deployed in a mini-excavator. The results pertaining to different control parameters confirm the theoretical expectations via pole-zero locations. By using proposed self-tuning controller, the vibrations are almost eliminated after only one overshoot for different operation conditions. The overshoots are also reduced with less decrease of the response time. In addition, the energy-saving capability of independent metering system is still not affected by the improvement of controllability.

  15. Robust vibration control at critical resonant modes using indirect-driven self-sensing actuation in mechatronic systems. (United States)

    Hong, Fan; Pang, Chee Khiang


    This paper presents an improved indirect-driven self-sensing actuation circuit for robust vibration control of piezoelectrically-actuated flexible structures in mechatronic systems. The circuit acts as a high-pass filter and provides better self-sensing strain signals with wider sensing bandwidth and higher signal-to-noise ratio. An adaptive non-model-based control is used to compensate for the structural vibrations using the strain signals from the circuit. The proposed scheme is implemented in a PZT-actuated suspension of a commercial dual-stage hard disk drive. Experimental results show improvements of 50% and 75% in the vibration suppression at 5.4kHz and 21kHz respectively, compared to the conventional PI control. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Hemispheric specificity for proprioception: Postural control of standing following right or left hemisphere damage during ankle tendon vibration. (United States)

    Duclos, Noémie C; Maynard, Luc; Abbas, Djawad; Mesure, Serge


    Right brain damage (RBD) following stroke often causes significant postural instability. In standing (without vision), patients with RBD are more unstable than those with left brain damage (LBD). We hypothesised that this postural instability would relate to the cortical integration of proprioceptive afferents. The aim of this study was to use tendon vibration to investigate whether these changes were specific to the paretic or non-paretic limbs. 14 LBD, 12 RBD patients and 20 healthy subjects were included. Displacement of the Centre of Pressure (CoP) was recorded during quiet standing, then during 3 vibration conditions (80 Hz - 20s): paretic limb, non-paretic limb (left and right limbs for control subjects) and bilateral. Vibration was applied separately to the peroneal and Achilles tendons. Mean antero-posterior position of the CoP, variability and velocity were calculated before (4s), during and after (24s) vibration. For all parameters, the strongest perturbation was during Achilles vibrations. The Achilles non-paretic condition induced a larger backward displacement than the Achilles paretic condition. This condition caused specific behaviour on the velocity: the LBD group was perturbed at the onset of the vibrations, but gradually recovered their stability; the RBD group was significantly perturbed thereafter. After bilateral Achilles vibration, RBD patients required the most time to restore initial posture. The reduction in use of information from the paretic limb may be a central strategy to deal with risk-of-fall situations such as during Achilles vibration. The postural behaviour is profoundly altered by lesions of the right hemisphere when proprioception is perturbed. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Active vibration control for a smart panel with enhanced acoustic performances (United States)

    Ripamonti, Francesco; Baro, Simone; Molgora, Manuel


    The spread of smart structures has recorded a significant increase during the last decades. Nowadays these solutions are applied in various fields such as aerospace, automotive and civil constructions. This kind of structures was born in the past in order to cope with the high vibrations that every lightweight structure has to face. In order to reduce weight designers usually decide to use very thin and lightweight structures. In the automotive field, for example, a reduced fuel consumption is obtained employing lightweight materials. However, in general a worsening of the vibroacoustic comfort is obtained with undesired vibrations that can be really annoying for passengers and dangerous for the structure itself. This work presents an innovative smart plate that is able to actively vary its dynamic properties, by means of an IMSC control logic, in order to improve the acoustic performances. An investigation about the system response in the high frequency range allowed to assess the behavior in terms of absorption, reflection coefficient and transmission loss.

  18. Vibration control of a class of semiactive suspension system using neural network and backstepping techniques (United States)

    Zapateiro, M.; Luo, N.; Karimi, H. R.; Vehí, J.


    In this paper, we address the problem of designing the semiactive controller for a class of vehicle suspension system that employs a magnetorheological (MR) damper as the actuator. As the first step, an adequate model of the MR damper must be developed. Most of the models found in literature are based on the mechanical behavior of the device, with the Bingham and Bouc-Wen models being the most popular ones. These models can estimate the damping force of the device taking the control voltage and velocity inputs as variables. However, the inverse model, i.e., the model that computes the control variable (generally the voltage) is even more difficult to find due to the numerical complexity that implies the inverse of the nonlinear forward model. In our case, we develop a neural network being able to estimate the control voltage input to the MR damper, which is necessary for producing the optimal force predicted by the controller so as to reduce the vibrations. The controller is designed following the standard backstepping technique. The performance of the control system is evaluated by means of simulations in MATLAB/Simulink.

  19. Observer Based Optimal Vibration Control of a Full Aircraft System Having Active Landing Gears and Biodynamic Pilot Model

    Directory of Open Access Journals (Sweden)

    Hakan Yazici


    Full Text Available This paper deals with the design of an observed based optimal state feedback controller having pole location constraints for an active vibration mitigation problem of an aircraft system. An eleven-degree-of-freedom detailed full aircraft mathematical model having active landing gears and a seated pilot body is developed to control and analyze aircraft vibrations caused by runway excitation, when the aircraft is taxiing. Ground induced vibration can contribute to the reduction of pilot’s capability to control the aircraft and cause the safety problem before take-off and after landing. Since the state variables of the pilot body are not available for measurement in practice, an observed based optimal controller is designed via Linear Matrix Inequalities (LMIs approach. In addition, classical LQR controller is designed to investigate effectiveness of the proposed controller. The system is then simulated against the bump and random runway excitation. The simulation results demonstrate that the proposed controller provides significant improvements in reducing vibration amplitudes of aircraft fuselage and pilot’s head and maintains the safety requirements in terms of suspension stroke and tire deflection.

  20. Research on Spillover Effects for Vibration Control of Piezoelectric Smart Structures by ANSYS

    Directory of Open Access Journals (Sweden)

    Xingjian Dong


    Full Text Available To control vibration of a piezoelectric smart structure, a controller is usually designed based on a reduced order model (ROM of the system. When such a ROM based controller operates in closed loop with the actual structure, spillover phenomenon occurs because the unmodeled dynamics, which are not included in ROM, will be excited. In this paper, a new approach aiming at investigating spillover effects in ANSYS software is presented. By using the ANSYS parametric design language (APDL, the ROM based controller is integrated into finite element model to provide an accurate representation of what will happen when the controller is connected to the real plant. Therefore, the issues of spillover effects can be addressed in the closed loop simulation. Numerical examples are presented for investigating spillover effects of a cantilever piezoelectric plate subjected to various types of loading. The importance of considering spillover effects in closed loop simulation of piezoelectric smart structures is demonstrated. Moreover, the present study may provide an efficient method especially beneficial for preliminary design of piezoelectric smart structure to evaluate the performance of candidate control laws in finite element environment considering spillover effects.

  1. Bioelectrical activity of the pelvic floor muscles during synchronous whole-body vibration--a randomized controlled study. (United States)

    Stania, Magdalena; Chmielewska, Daria; Kwaśna, Krystyna; Smykla, Agnieszka; Taradaj, Jakub; Juras, Grzegorz


    More and more frequently stress urinary incontinence affects young healthy women. Hence, early implementation of effective preventive strategies in nulliparous continent women is essential, including pelvic floor muscle training. An initial evaluation based on the bioelectrical activity of the pelvic floor muscles (PFM) during whole-body vibration (WBV) would help to devise the best individualized training for prevention of stress urinary incontinence in woman. We hypothesized that synchronous WBV enhances bioelectrical activity of the PFM which depends on vibration frequency and peak-to-peak vibration displacement. The sample consisted of 36 nulliparous continent women randomly allocated to three comparative groups. Group I and II subjects participated in synchronous whole-body vibrations on a vibration platform; the frequency and peak-to-peak displacement of vibration were set individually for each group. Control participants performed exercises similar to those used in the study groups but without the concurrent application of vibrations. Pelvic floor surface electromyography (sEMG) activity was recorded using a vaginal probe during three experimental trials limited to 30s, 60s and 90 s. The mean amplitude and variability of the signal were normalized to the Maximal Voluntary Contraction - MVC. Friedman's two-way ANOVA revealed a statistically significant difference in the mean normalized amplitudes (%MVC) of the sEMG signal from the PFM during 60s- and 90 s-trials between the group exposed to high-intensity WBV and control participants (p pelvic floor muscle fatigue. The trial was registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12615000966594); registration date: 15/09/2015.

  2. Optimum Tuning of a Gyroscopic Vibration Absorber Using Coupled Gyroscopes for Vibration Control of a Vertical Cantilever Beam

    Directory of Open Access Journals (Sweden)

    F. Ünker


    Full Text Available This paper deals with the investigation of optimum values of the stiffness and damping which connect two gyroscopic systems formed by two rotors mounted in gimbal assuming negligible masses for the spring, damper, and gimbal support. These coupled gyroscopes use two gyroscopic flywheels, spinning in opposing directions to have reverse precessions to eliminate the forces due to the torque existing in the torsional spring and the damper between gyroscopes. The system is mounted on a vertical cantilever with the purpose of studying the horizontal and vertical vibrations. The equation of motion of the compound system (gyro-beam system is introduced and solved to find the response measured on the primary system. This is fundamental to design, in some way, the dynamic absorber or neutralizer. On the other hand, the effect of the angular velocities of the gyroscopes are studied, and it is shown that the angular velocity (spin velocity of a gyroscope has a significant effect on the behavior of the dynamic motion. Correctness of the analytical results is verified by numerical simulations. The comparison with the results from the derivation of the corresponding frequency equations shows that the optimized stiffness and damping values are very accurate.

  3. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  4. Semi-active damping with negative stiffness for multi-mode cable vibration mitigation: approximate collocated control solution (United States)

    Weber, F.; Distl, H.


    This paper derives an approximate collocated control solution for the mitigation of multi-mode cable vibration by semi-active damping with negative stiffness based on the control force characteristics of clipped linear quadratic regulator (LQR). The control parameters are derived from optimal modal viscous damping and corrected in order to guarantee that both the equivalent viscous damping coefficient and the equivalent stiffness coefficient of the semi-active cable damper force are equal to their desired counterparts. The collocated control solution with corrected control parameters is numerically validated by free decay tests of the first four cable modes and combinations of these modes. The results of the single-harmonic tests demonstrate that the novel approach yields 1.86 times more cable damping than optimal modal viscous damping and 1.87 to 2.33 times more damping compared to a passive oil damper whose viscous damper coefficient is optimally tuned to the targeted mode range of the first four modes. The improvement in case of the multi-harmonic vibration tests, i.e. when modes 1 and 3 and modes 2 and 4 are vibrating at the same time, is between 1.55 and 3.81. The results also show that these improvements are obtained almost independent of the cable anti-node amplitude. Thus, the proposed approximate real-time applicable collocated semi-active control solution which can be realized by magnetorheological dampers represents a promising tool for the efficient mitigation of stay cable vibrations.

  5. Vibration control in semi-active suspension of the experimental off-road vehicle using information about suspension deflection

    Directory of Open Access Journals (Sweden)

    Kasprzyk Jerzy


    Full Text Available The efficiency of vibration control in an automotive semi-active suspension system depends on the quality of information from sensors installed in the vehicle, including information about deflection of the suspension system. The control algorithm for vibration attenuation of the body takes into account its velocity as well as the relative velocity of the suspension. In this paper it is proposed to use the Linear Variable Differential Transformer (LVDT unit to measure the suspension deflection and then to estimate its relative velocity. This approach is compared with a typical solution implemented in such applications, where the relative velocity is calculated by processing signals acquired from accelerometers placed on the body and on the chassis. The experiments performed for an experimental All-Terrain Vehicle (ATV confirm that using LVDT units allows for improving ride comfort by better vibration attenuation of the body.

  6. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part I: Theory

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar


    actuators fixed directly in the blades. However, due to the impracticability and problems by fixing actuators in the rotating blades, it is for practical application of great interest to study whether the vibrations can be controlled using shaft-based actuators, i.e. electro-magnetic bearings......This is the first paper in a two-part study on active rotor-blade vibration control. Blade faults are a major problem in bladed machines, such as turbines and compressors. Moreover, increasing demands for higher efficiency, lower weight and higher speed imply that blades become even more...... susceptible to vibrational problems. Passive damping methods, such as frictional damping, are typically used for this kind of machines, working very well at the specific design conditions. However, when the running conditions exceed the design specification, then passive damping devices become inefficient...

  7. Controllable parametric excitation effect on linear and nonlinear vibrational resonances in the dynamics of a buckled beam (United States)

    Djomo Mbong, T. L. M.; Siewe Siewe, M.; Tchawoua, C.


    In this study, the effect of a controllable parametric excitation on both linear and nonlinear vibrational resonances on the dynamic of a buckled beam excited by a combination of uncontrollable low- and high-frequency periodic forces are investigated. First of all, the beam dynamic is assumed to be constrained by two periodic and independent ambient solicitations, such as wind and earthquake. An axial load of the beam represented by a periodic and parametric excitation is used to control the vibrational resonance phenomenon, induced by the presence of the two external excitations. Approximate analytical expressions for the linear response and the high-frequency force amplitude at which linear vibrational resonance occurs are obtained. An analytical expression of the amplitude of the nonlinear response at the superharmonic equal to the double of the low-frequency, is obtained. For all these expressions, we show the effect of the parametric excitation. We compare all the obtained results with the ones of the case where, the parametric force is absent. It is shown that, the presence of the parametric excitation permit the suppression of both linear and nonlinear vibrational resonances. Moreover, the vibration amplitudes of the buckled beam are significantly reduced, around certain threshold values for the amplitude and the frequency of the parametric excitation.

  8. Experiment on vibration control of a two-link flexible manipulator using an input shaper and adaptive positive position feedback

    Directory of Open Access Journals (Sweden)

    ZhongYi Chu


    Full Text Available This article presents a novel approach for actively suppressing the vibration within a two-link flexible manipulator to adapt the variation in the model parameters, which is composed of an input shaper and multimode adaptive positive position feedback. Input shaper is applied to shape the command to avoid the flexible vibration in the manoeuvre motion, and the residual vibration can be suppressed by a piezo actuator with the adaptive positive position feedback approach. To demonstrate the approach, two sets of piezoelectric actuator/stain gauge sensor pairs are bonded to the surface of the two-link flexible manipulator; slewing of the flexible link induces vibrations in the link that persist long after the motors stop moving. Vibration suppression is achieved through a combined scheme of input shaper–based motor motion control and an adaptive positive position feedback–based piezo actuator controller. Experimental results show the effectiveness of the proposed approach and its suitability for implementation in an existing robot.

  9. Application of Energy Finite Element Method in Active Vibration Control of Piezoelectric Intelligent Beam

    Directory of Open Access Journals (Sweden)

    Jinhua Xie


    Full Text Available Based on the transmission and equilibrium relationship of vibration energy in beam-like structures, the Galerkin weighted residual method was applied to equation discretization. An equivalent transformation of feedback element was suggested to develop the Energy Finite Element model of a composite piezoelectric cantilever beam driven by harmonic excitation on lateral direction, with both systems with and without time delay being studied and the power input estimation of harmonic excitation was discussed for the resolution of Energy Finite Element function. Then the energy density solutions of the piezoelectric coupling beam through Energy Finite Element Method (EFEM and classical wave theory were compared to verify the EFEM model, which presented a good accordance. Further investigation was undertaken about the influence of control parameters including the feedback gain and arrangement of piezoelectric patches on characteristics of system energy density distribution.

  10. Vibration control of a cable-stayed bridge using electromagnetic induction based sensor integrated MR dampers

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sang Won [University of Western Ontario, London (Canada); Koo, Jeong Hoi [Miami University, Oxford (United States); Jo, Ji Seong [POSCO, Seongnam (Korea, Republic of)


    This paper presents a novel electromagnetic induction (EMI) system integrated in magneto rheological (MR) dampers: The added EMI system converts reciprocal motions of MR damper into electiral energy (electromotive force or emf) according to the Faraday's law of electromagnetic induction. Maximum energy dissipation algorithm (MEDA) is employed to regulate the MR dampers because it strives to simplify a complex design process by employing the Lyapunov's direct approach. The emf signal, produced from the EMI, provides the necessary measurement information (i.e., realtive velocity across the damper) for the MEDA controller. Thus, the EMI acts as a sensor in the proposed MR-EMI system. In order to evaluate the performance and robustness of the MR-EMI sensor system with the MEDA control, this study performed an extensive simulation study using the first generation benchmark cable-stayed bridge. Moreover, it compared the performance and the robustness of proposed system with those of Clipped-Optimal Control (COC) and Sliding Mode Control (SMC), which were previously studied for the benchmark cable-stayed bridge. The results show that the MR-EMI system reduced the vibrations of the bridge structure more than those of COC and SMC and show more robust performance than that of SMC. These results suggest that EMIs can be used cost-effective sensing devices for MR damper control systems without compromising the performance of them.

  11. Experiments on Optimal Vibration Control of a Flexible Beam Containing Piezoelectric Sensors and Actuators

    Directory of Open Access Journals (Sweden)

    Gustavo L.C.M. Abreu


    Full Text Available In this paper, a digital regulator is designed and experimentally implemented for a flexible beam type structure containing piezoelectric sensors and actuators by using optimal control design techniques. The controller consists of a linear quadratic regulator with a state estimator, namely a Kalman observer. The structure is a cantilever beam containing a set of sensor/actuator PVDF/PZT ceramic piezoelectric patches bonded to the beam surface at the optimal location obtained for the first three vibration modes. The equations of motion of the beam are developed by using the assumed modes technique for flexible structures in infinite-dimensional models. This paper uses a method of minimizing the effect of the removed higher order modes on the low frequency dynamics of the truncated model by adding a zero frequency term to the low order model of the system. A measure of the controllability and observability of the system based on the modal cost function for flexible structures containing piezoelectric elements (intelligent structures is used. The observability and controllability measures are determined especially to guide the placement of sensors and actuators, respectively. The experimental and numerical transfer functions are adjusted by using an optimization procedure. Experimental results illustrate the optimal control design of a cantilever beam structure.

  12. Design of a new adaptive fuzzy controller and its application to vibration control of a vehicle seat installed with an MR damper (United States)

    Phu, Do Xuan; Shin, Do Kyun; Choi, Seung-Bok


    This paper presents a new adaptive fuzzy controller featuring a combination of two different control methodologies: H infinity control technique and sliding mode control. It is known that both controllers are powerful in terms of high performance and robust stability. However, both control methods require an accurate dynamic model to design a state variable based controller in order to maintain their advantages. Thus, in this work a fuzzy control method which does not require an accurate dynamic model is adopted and two control methodologies are integrated to maintain the advantages even in an uncertain environment of the dynamic system. After a brief explanation of the interval type 2 fuzzy logic, a new adaptive fuzzy controller associated with the H infinity control and sliding mode control is formulated on the basis of Lyapunov stability theory. Subsequently, the formulated controller is applied to vibration control of a vehicle seat equipped with magnetorheological fluid damper (MR damper in short). An experimental setup for realization of the proposed controller is established and vibration control performances such as acceleration at the driver’s seat are evaluated. In addition, in order to demonstrate the effectiveness of the proposed controller, a comparative work with two existing controllers is undertaken. It is shown through simulation and experiment that the proposed controller can provide much better vibration control performance than the two existing controllers.

  13. Vibration Control of Structures using Vibro-Impact Nonlinear Energy Sinks

    Directory of Open Access Journals (Sweden)

    M. Ahmadi


    Full Text Available Using Vibro-Impact Nonlinear Energy Sinks (VI NESs is one of the novel strategies to control structural vibrations and mitigate their seismic response. In this system, a mass is tuned on the structure floor, so that it has a specific distance from an inelastic constraint connected to the floor mass. In case of structure stimulation, the displaced VI NES mass collides with the  inelastic constraint and upon impacts, energy is dissipated. In the present work, VI NES is studied when its parameters, including clearance and stiffness ratio, are simultaneously optimized. Harmony search as a recent meta-heuristic algorithm is efficiently specialized and utilized for the aforementioned continuous optimization problem. The optimized attached VI NES is thus shown to be capable of interacting with the primary structure over a wide range of frequencies. The resulting controlled response is then investigated, in a variety of low and medium rise steel moment frames, via nonlinear dynamic time history analyses. Capability of the VI NES to dissipate siesmic input energy of earthquakes and their capabilitiy in reducing response of srtructures effectively, through vibro-impacts between the energy sink’s mass and the floor mass, is discussed by extracting several performance indices and the corresponding Fourier spectra. Results of the numerical simulations done on some structural model examples reveal that the optimized VI NES has caused successive redistribution of energy from low-frequency high-amplitude vibration modes to high-frequency low-amplitude modes, bringing about the desired attenuation of the structural responses.

  14. Active controls technology to maximize structural efficiency (United States)

    Hoy, J. M.; Arnold, J. M.


    The implication of the dependence on active controls technology during the design phase of transport structures is considered. Critical loading conditions are discussed along with probable ways of alleviating these loads. Why fatigue requirements may be critical and can only be partially alleviated is explained. The significance of certain flutter suppression system criteria is examined.

  15. Technological Improvements for Digital Fire Control Systems (United States)


    Final Technical Status Report For DOTC-12-01-INIT061 Technological Improvements for Digital Fire Control Systems Reporting Period: 30 Sep...Processes 100% 6 Quarterly Technical and Business Status Report 100% 7 Component design development for gun components not funded 8 Materials Dev

  16. Investigations of an Accelerometer-based Disturbance Feedforward Control for Vibration Suppression in Adaptive Optics of Large Telescopes (United States)

    Glück, Martin; Pott, Jörg-Uwe; Sawodny, Oliver


    Adaptive Optics (AO) systems in large telescopes do not only correct atmospheric phase disturbances, but they also telescope structure vibrations induced by wind or telescope motions. Often the additional wavefront error due to mirror vibrations can dominate the disturbance power and contribute significantly to the total tip-tilt Zernike mode error budget. Presently, these vibrations are compensated for by common feedback control laws. However, when observing faint natural guide stars (NGS) at reduced control bandwidth, high-frequency vibrations (>5 Hz) cannot be fully compensated for by feedback control. In this paper, we present an additional accelerometer-based disturbance feedforward control (DFF), which is independent of the NGS wavefront sensor exposure time to enlarge the “effective servo bandwidth”. The DFF is studied in a realistic AO end-to-end simulation and compared with commonly used suppression concepts. For the observation in the faint (>13 mag) NGS regime, we obtain a Strehl ratio by a factor of two to four larger in comparison with a classical feedback control. The simulation realism is verified with real measurement data from the Large Binocular Telescope (LBT); the application for on-sky testing at the LBT and an implementation at the E-ELT in the MICADO instrument is discussed.

  17. Parameter optimization of an inerter-based isolator for passive vibration control of Michelangelo's Rondanini Pietà (United States)

    Siami, A.; Karimi, H. R.; Cigada, A.; Zappa, E.; Sabbioni, E.


    Preserving cultural heritage against earthquake and ambient vibrations can be an attractive topic in the field of vibration control. This paper proposes a passive vibration isolator methodology based on inerters for improving the performance of the isolation system of the famous statue of Michelangelo Buonarroti Pietà Rondanini. More specifically, a five-degree-of-freedom (5DOF) model of the statue and the anti-seismic and anti-vibration base is presented and experimentally validated. The parameters of this model are tuned according to the experimental tests performed on the assembly of the isolator and the structure. Then, the developed model is used to investigate the impact of actuation devices such as tuned mass-damper (TMD) and tuned mass-damper-inerter (TMDI) in vibration reduction of the structure. The effect of implementation of TMDI on the 5DOF model is shown based on physical limitations of the system parameters. Simulation results are provided to illustrate effectiveness of the passive element of TMDI in reduction of the vibration transmitted to the statue in vertical direction. Moreover, the optimal design parameters of the passive system such as frequency and damping coefficient will be calculated using two different performance indexes. The obtained optimal parameters have been evaluated by using two different optimization algorithms: the sequential quadratic programming method and the Firefly algorithm. The results prove significant reduction in the transmitted vibration to the structure in the presence of the proposed tuned TMDI, without imposing a large amount of mass or modification to the structure of the isolator.

  18. Topological material layout in plates for vibration suppression and wave propagation control

    DEFF Research Database (Denmark)

    Larsen, Anders Astrup; Laksafoss, B.; Jensen, Jakob Søndergaard


    plate theory coupled with analytical sensitivity analysis using the adjoint method and an iterative design update procedure based on a mathematical programming tool. We demonstrate the capability of the method by designing bi-material plates that, when subjected to harmonic excitation, either......We propose a topological material layout method to design elastic plates with optimized properties for vibration suppression and guided transport of vibration energy. The gradient-based optimization algorithm is based on a finite element model of the plate vibrations obtained using the Mindlin...... effectively suppress the overall vibration level or alternatively transport energy in predefined paths in the plates, including the realization of a ring wave device....

  19. Assessment of control technology for stationary sources. Volume II: control technology data tables. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Minicucci, D.; Herther, M.; Babb, L.; Kuby, W.


    This report, the Control Technology Data Tables, is the second volume of the three-volume final report for the contract. It presents in tabular format, qualitative descriptions of control options for the various sources and quantitative information on control technology cost, efficiency, reliability, energy consumption, other environmental impacts and application status. Also included is a code list which classifies the stationary sources examined by industry, process, and emission source.

  20. Whole body vibration exercise for chronic low back pain: study protocol for a single-blind randomized controlled trial (United States)


    Background Low back pain affects approximately 80% of people at some stage in their lives. Exercise therapy is the most widely used nonsurgical intervention for low back pain in practice guidelines. Whole body vibration exercise is becoming increasingly popular for relieving musculoskeletal pain and improving health-related quality of life. However, the efficacy of whole body vibration exercise for low back pain is not without dispute. This study aims to estimate the effect of whole body vibration exercise for chronic low back pain. Methods/Design We will conduct a prospective, single-blind, randomized controlled trial of 120 patients with chronic low back pain. Patients will be randomly assigned into an intervention group and a control group. The intervention group will participate in whole body vibration exercise twice a week for 3 months. The control group will receive general exercise twice a week for 3 months. Primary outcome measures will be the visual analog scale for pain, the Oswestry Disability Index and adverse events. The secondary outcome measures will include muscle strength and endurance of spine, trunk proprioception, transversus abdominis activation capacity, and quality of life. We will conduct intention-to-treat analysis if any participants withdraw from the trial. Discussion Important features of this study include the randomization procedures, single-blind, large sample size, and a standardized protocol for whole body vibration in chronic low back pain. This study aims to determine whether whole body vibration exercise produces more beneficial effects than general exercise for chronic low back pain. Therefore, our results will be useful for patients with chronic low back pain as well as for medical staff and health-care decision makers. Trial registration Chinese Clinical Trial Registry: ChiCTR-TRC-13003708. PMID:24693945

  1. Vibration control of a semi-active railway vehicle suspension with magneto-rheological dampers

    Directory of Open Access Journals (Sweden)

    Jong-Seok Oh


    Full Text Available This article presents vibration control performances of a semi-active railway vehicle suspension system using a magneto-rheological damper tested on the roller rig. In order to evaluate control performances, a mathematical railway vehicle model with 15 degrees of freedom is first derived to represent the lateral, yaw and roll motions of the car body, bogie frame, and wheel set, respectively. Based on the formulated model, the design parameters of magneto-rheological damper are determined to undertake a compatible comparison with dynamic performances of conventional (existing passive railway vehicle suspension system. The designed magneto-rheological damper is manufactured and its field-dependent damping force characteristics are experimentally evaluated. Subsequently, in order to enhance the ride quality of a railway vehicle suspension equipped with magneto-rheological damper, a skyhook controller associated with an extended Kalman filter is designed in a state space representation. The railway suspension system incorporated with the car body and two bogies is then experimentally set up on the roller rig in order to evaluate the ride quality. It is demonstrated from experimental realization of the controller that the ride quality of the suspension system with magneto-rheological damper can be significantly enhanced compared with the existing passive suspension system.

  2. Vibration control for the parametrically excited van der Pol oscillator by nonlocal feedback

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, Attilio [Via Alfredo Casella 3, 00013 Mentana, Rome (Italy)


    A nonlocal feedback is used for the control of nonlinear vibrations in a parametrically excited van der Pol oscillator. A nonlocal control force is introduced in order to obtain a third-order nonlinear differential equation (jerk dynamics). Using the asymptotic perturbation method, two slow flow equations on the amplitude and phase of the response are obtained, and subsequently the performance of the control strategy is investigated. Parametric excitation-response and frequency-response curves are shown. Uncontrolled and controlled systems are compared, and the appropriate choices of the feedback gains for reducing the amplitude peak of the response are found. Energy considerations are used in order to study the existence and characteristics of limit cycles of the slow flow equations. A limit cycle corresponds to a two-period modulated motion for the van der Pol oscillator. To exclude the possibility of quasi-periodic motion and to reduce the amplitude peak of the parametric resonance, appropriate choices of the feedback gains are found. Numerical simulation confirms the validity of the new method.

  3. Semi-Active Control of Three-Dimensional Vibrations of an Inclined Sag Cable with Magnetorheological Dampers

    DEFF Research Database (Denmark)

    Zhou, Q.; Nielsen, Søren R.K.; Qu, W. L.


    Three-dimensional semi-active vibration control of an inclined sag cable with discrete magnetorheological (MR) dampers is investigated in this paper using the finite difference method (FDM). A modified Dahl model is used to describe the dynamic property of MR damper. The nonlinear equations of mo...

  4. Evaluation of an occupational health intervention programme on whole-body vibration in forklift truck drivers: a controlled trial

    NARCIS (Netherlands)

    Hulshof, C. T. J.; Verbeek, J. H. A. M.; Braam, I. T. J.; Bovenzi, M.; van Dijk, F. J. H.


    OBJECTIVES: To evaluate process and outcome of a multifaceted occupational health intervention programme on whole-body vibration (WBV) in forklift truck drivers. METHODS: An experimental pretest/post-test control group study design. The authors trained occupational health services (OHS) in the

  5. GOES-R Active Vibration Damping Controller Design, Implementation, and On-Orbit Performance (United States)

    Clapp, Brian R.; Weigl, Harald J.; Goodzeit, Neil E.; Carter, Delano R.; Rood, Timothy J.


    GOES-R series spacecraft feature a number of flexible appendages with modal frequencies below 3.0 Hz which, if excited by spacecraft disturbances, can be sources of undesirable jitter perturbing spacecraft pointing. In order to meet GOES-R pointing stability requirements, the spacecraft flight software implements an Active Vibration Damping (AVD) rate control law which acts in parallel with the nadir point attitude control law. The AVD controller commands spacecraft reaction wheel actuators based upon Inertial Measurement Unit (IMU) inputs to provide additional damping for spacecraft structural modes below 3.0 Hz which vary with solar wing angle. A GOES-R spacecraft dynamics and attitude control system identified model is constructed from pseudo-random reaction wheel torque commands and IMU angular rate response measurements occurring over a single orbit during spacecraft post-deployment activities. The identified Fourier model is computed on the ground, uplinked to the spacecraft flight computer, and the AVD controller filter coefficients are periodically computed on-board from the Fourier model. Consequently, the AVD controller formulation is based not upon pre-launch simulation model estimates but upon on-orbit nadir point attitude control and time-varying spacecraft dynamics. GOES-R high-fidelity time domain simulation results herein demonstrate the accuracy of the AVD identified Fourier model relative to the pre-launch spacecraft dynamics and control truth model. The AVD controller on-board the GOES-16 spacecraft achieves more than a ten-fold increase in structural mode damping of the fundamental solar wing mode while maintaining controller stability margins and ensuring that the nadir point attitude control bandwidth does not fall below 0.02 Hz. On-orbit GOES-16 spacecraft appendage modal frequencies and damping ratios are quantified based upon the AVD system identification, and the increase in modal damping provided by the AVD controller for each structural

  6. Closed-loop control of vibrational population in CO{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Wells, E; Jochim, Bethany; Gregerson, Neal; Averin, R [Department of Physics, Augustana College, Sioux Falls, SD 57197 (United States); McKenna, J; Sayler, A M; Zohrabi, M; Carnes, K D; Ben-Itzhak, I, E-mail: eric.wells@augie.ed [J R Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)


    An adaptive closed-loop feedback system is used to determine the optimal pulse shapes for manipulating the branching ratio of CO{sup 2+} following ionization by an intense laser pulse. For this target, selecting between the CO{sup 2+} and C{sup +} + O{sup +} final states requires control of the vibrational population distribution in the transient CO{sup 2+}. The ability to both suppress and enhance CO{sup 2+} relative to C{sup +} + O{sup +} is observed, with shaped pulses surpassing a transform-limited pulse by factors of about 10 for suppression and 2 for enhancement. When optimizing small channels, such as non-dissociative CO{sup 2+}, we demonstrate that a feedback signal obtained via a pulse counting technique is more robust than the more typical current mode signal collection. Furthermore, we demonstrate how the pulse counting technique allows control of a coincidence channel, specifically C{sup +} + O{sup +}, by using logical electronic gates. Using these coincidence signals allows more specific final states to be incorporated into closed-loop control.

  7. Bringing (Century-Old) Technology into the Classroom, Part II: Teaching Vibrations and Waves, Electricity and Magnetism, and Optics with Antiques (United States)

    Jewett, John W., Jr.


    This is the second in a series of two articles on using antique devices to teach introductory physics. As mentioned in the first article, students can more clearly see the physics required for the operation of antique devices than for modern-day technological devices. This article further discusses antiques used to teach vibrations and waves,…

  8. Femtochemistry in the electronic ground state: Dynamic Stark control of vibrational dynamics

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Thomas, Esben Folger; Henriksen, Niels Engholm


    We study the interplay of vibrational and rotational excitation in a diatomic molecule due to the non-resonant dynamic Stark effect. With a fixed peak intensity, optimal Gaussian pulse durations for maximizing vibrational or rotational transitions are obtained analytically and confirmed numerically...

  9. Active vibration control for underwater signature reduction of a navy ship

    NARCIS (Netherlands)

    Basten, T.G.H.; Berkhoff, Arthur P.; Vermeulen, Ruud


    Dutch navy ships are designed and built to have a low underwater signature. For low frequencies however, tonal vibrations of a gearbox can occur, which might lead to increased acoustic signatures. These vibrations are hard to reduce by passive means. To investigate the possibilities of active

  10. Vibration control in forge hammers. [by shock wave damping in foundation platform (United States)

    Moise, F.; Lazarescu, C.


    Special measures are discussed for calculating, designing and executing a forge hammer foundation, so that the vibrations that occur during its working will not be transmitted to neighboring machinery, workrooms and offices. These vibrations are harmful to the workers near the forge hammer.

  11. Dynamics and genetic fuzzy neural network vibration control design of a smart flexible four-bar linkage mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Rong Bao, E-mail:; Rui Xiaoting [Nanjing University of Science and Technology, Institute of Launch Dynamics (China); Tao Ling [Chinese Academy of Sciences (ASIPP), Institute of Plasma Physics (China)


    In this paper, a dynamic modeling method and an active vibration control scheme for a smart flexible four-bar linkage mechanism featuring piezoelectric actuators and strain gauge sensors are presented. The dynamics of this smart mechanism is described by the Discrete Time Transfer Matrix Method of Multibody System (MS-DTTMM). Then a nonlinear fuzzy neural network control is employed to suppress the vibration of this smart mechanism. For improving the dynamic performance of the fuzzy neural network, a genetic algorithm based on the MS-DTTMM is designed offline to tune the initial parameters of the fuzzy neural network. The MS-DTTMM avoids the global dynamics equations of the system, which results in the matrices involved are always very small, so the computational efficiency of the dynamic analysis and control system optimization can be greatly improved. Formulations of the method as well as a numerical simulation are given to demonstrate the proposed dynamic method and control scheme.

  12. Vibration Pattern Imager (VPI): A control and data acquisition system for scanning laser vibrometers (United States)

    Rizzi, Stephen A.; Brown, Donald E.; Shaffer, Thomas A.


    The Vibration Pattern Imager (VPI) system was designed to control and acquire data from scanning laser vibrometer sensors. The PC computer based system uses a digital signal processing (DSP) board and an analog I/O board to control the sensor and to process the data. The VPI system was originally developed for use with the Ometron VPI Sensor, but can be readily adapted to any commercially available sensor which provides an analog output signal and requires analog inputs for control of mirror positioning. The sensor itself is not part of the VPI system. A graphical interface program, which runs on a PC under the MS-DOS operating system, functions in an interactive mode and communicates with the DSP and I/O boards in a user-friendly fashion through the aid of pop-up menus. Two types of data may be acquired with the VPI system: single point or 'full field.' In the single point mode, time series data is sampled by the A/D converter on the I/O board (at a user-defined sampling rate for a selectable number of samples) and is stored by the PC. The position of the measuring point (adjusted by mirrors in the sensor) is controlled via a mouse input. The mouse input is translated to output voltages by the D/A converter on the I/O board to control the mirror servos. In the 'full field' mode, the measurement point is moved over a user-selectable rectangular area. The time series data is sampled by the A/D converter on the I/O board (at a user-defined sampling rate for a selectable number of samples) and converted to a root-mean-square (rms) value by the DSP board. The rms 'full field' velocity distribution is then uploaded for display and storage on the PC.

  13. The future for weed control and technology. (United States)

    Shaner, Dale L; Beckie, Hugh J


    This review is both a retrospective (what have we missed?) and prospective (where are we going?) examination of weed control and technology, particularly as it applies to herbicide-resistant weed management (RWM). Major obstacles to RWM are discussed, including lack of diversity in weed management, unwillingness of many weed researchers to conduct real integrated weed management research or growers to accept recommendations, influence or role of agrichemical marketing and governmental policy and lack of multidisciplinary research. We then look ahead to new technologies that are needed for future weed control in general and RWM in particular, in areas such as non-chemical and chemical weed management, novel herbicides, site-specific weed management, drones for monitoring large areas, wider application of 'omics' and simulation model development. Finally, we discuss implementation strategies for integrated weed management to achieve RWM, development of RWM for developing countries, a new classification of herbicides based on mode of metabolism to facilitate greater stewardship and greater global exchange of information to focus efforts on areas that maximize progress in weed control and RWM. There is little doubt that new or emerging technologies will provide novel tools for RMW in the future, but will they arrive in time? © 2013 Her Majesty the Queen in Right of Canada Pest Management Science © 2013 Society of Chemical Industry.


    Directory of Open Access Journals (Sweden)

    Atta Oveisi


    Full Text Available The lack of robustness of the mechanical systems due to the unmodeled dynamics and the external disturbances withholds the performance and optimality of the structures. In this paper, this deficiency is obviated in order to reach the desired robust stability and performance on smart structures. For this purpose a multi-objective robust control strategy is proposed for vibration suppression of a clamped-free smart beam with piezoelectric actuator and vibrometer sensor in an LMI framework which is capable of handling weighted exogenous input signals and provides desired pole placement and robust performance at the same time. An accurate model of a homogeneous beam is derived by means of the finite element modal analysis. Then a low order modal system is considered as the nominal model and remaining modes are left as the multiplicative unstructured uncertainty. Next, a robust controller with a regional pole placement constraint is designed based on the augmented plant composed of the nominal model and its accompanied uncertainty by solving a convex optimization problem. Finally, the robustness of the uncertain closed-loop model and the effect of performance index weights on the system output are investigated both in simulation and practice.

  15. Coupled rotor-fuselage vibration reduction with multiple frequency blade pitch control (United States)

    Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.


    A nonlinear coupled rotor/flexible fuselage analysis has been developed and used to study the effects of higher harmonic blade pitch control on the vibratory hub loads and fuselage acceleration levels. Previous results, obtained with this model have shown that conventional higher harmonic control (HHC) inputs aimed at hub shear reduction cause an increase in the fuselage accelerations and vice-versa. It was also found that for simultaneous reduction of hub shears and fuselage accelerations, a pitch input representing a combination of two higher harmonic components of different frequencies was needed. Subsequently, it was found that this input could not be implemented through a conventional swashplate. This paper corrects a mistake originally made in the representation of the multiple frequency pitch input and shows that such a pitch input can be only implemented in the rotating reference frame. A rigorous mathematical solution is found, for the pitch input in the rotating reference frame, which produces simultaneous reduction of hub shears and fuselage acceleration. New insight on vibration reduction in coupled rotor/fuselage systems is obtained from the sensitivity of hub shears to the frequency and amplitude of the open loop HHC signal in the rotating reference frame. Finally the role of fuselage flexibility in this class of problems is determined.

  16. Monitoring and control of vibrations due to blasting in Sumapaz tunnel, granting Bogotá-Girardot

    Directory of Open Access Journals (Sweden)

    Luis Humberto Pinto-Morales


    Full Text Available This article discusses the most relevant topics of the subject of vibration of the ground, from its generation and monitoring to the control of their effects. We emphasize on the use and interpretation of the dynamic data field, since the theoretical methods and testing laboratory at times are not sufficient to solve applied geotechnical problems; for example, in the case of the assessment of the impact of the blasting in the Sumapaz tunnel, Boquerón area, department of Cundinamarca, Colombia. The work is the result of studies carried out by company I.GEOSOTMINE LTDA., in coordination with the Research Group INGEOFISICA of Universidad Pedagógica y Tecnológica de Colombia, on the exploration of the subsoil, aimed at the monitoring and control of blasting caused by explosive and micro-trepidation, in several Colombian regions.

  17. Passive Vibration Control of a Semi-Submersible Floating Offshore Wind Turbine

    Directory of Open Access Journals (Sweden)

    Chao Li


    Full Text Available Floating offshore wind turbines have the potential to commercially convert the vast wind resource in deep-water area. Compared with fixed-bottom wind turbines, motions of the floating foundation complicate vibrations and loads of the wind turbine in offshore environment. To alleviate the responses of the wind turbine, this study investigates the use of fore–aft tuned mass damper (TMD in nacelle/tower for passive control of a semi-submersible offshore wind turbine. A simplified structural model, considering the degree-of-freedom of platform pitch and surge, tower tilt and TMD translation, is proposed in the light of motion features of semi-submersible platform. After identifying ten unknown parameters, the correctness of the deterministic model is validated by pitch free decay responses. The mass, stiffness and damping of TMD are optimized using both method of exhaustion and genetic algorithm to avoid local minimum. Six optimized TMD devices are evaluated under three kinds of realistic environment conditions. The control effectiveness is assessed by the extreme and fatigue response reduction ratios. It is found that the high stiffness TMDs that directly dissipate the energy of tower oscillation exhibit an overall stable performance. Similar to the spar-type foundation, the TMDs in the nacelle/tower are capable of extending the service life of floating wind turbines.

  18. Comprehensive aeroelastic analysis of helicopter rotor with trailing-edge flap for primary control and vibration control (United States)

    Shen, Jinwei

    A comprehensive aeroelastic analytical model of helicopter rotors with trailing-edge flaps for primary and vibration controls has been developed. The derivation of system equations is based on Hamilton principles, and implemented with finite element method in space and time. The blade element consists of fifteen degrees of freedom representing blade flap, lag, torsional, and axial deformations. Three aerodynamic models of flapped airfoils were implemented in the present analysis, the unsteady Hariharan-Leishman model for trailing-edge flaps without aerodynamic balance, a quasi-steady Theodorsen theory for an aerodynamic balanced trailing-edge flap, and table lookup based on wind tunnel test data. The trailing-edge flap deflections may be modeled as a degree of freedom so that the actuator dynamics can be captured properly. The coupled trim procedures for swashplateless rotor are solved in either wind tunnel trim or free flight condition. A multicyclic controller is also implemented to calculate the flap control inputs for minimization of vibratory rotor hub loads. The coupled blade equations of motion are linearized by using small perturbations about a steady trimmed solution. The aeroelastic stability characteristics of trailing-edge flap rotors is then determined from an eigenanalysis of the homogeneous equations using Floquet method. The correlation studies of a typical bearingless rotor and an ultralight teetering rotor are respectively based on wind tunnel test data and simulations of another comprehensive analysis (CAMRAD II). Overall, good correlations are obtained. Parametric study identifies that the effect of actuator dynamics cannot be neglected, especially for a torsionally soft smart actuator system. Aeroelastic stability characteristics of a trailing-edge flap rotor system are shown to be sensitive to flap aerodynamic and mass balances. Key parameters of trailing-edge flap system for primary rotor control are identified as blade pitch index angle

  19. Vibration control of a ship engine system using high-load magnetorheological mounts associated with a new indirect fuzzy sliding mode controller (United States)

    Phu, Do Xuan; Choi, Seung-Bok


    In this work, a new high-load magnetorheological (MR) fluid mount system is devised and applied to control vibration in a ship engine. In the investigation of vibration-control performance, a new modified indirect fuzzy sliding mode controller is formulated and realized. The design of the proposed MR mount is based on the flow mode of MR fluid, and it includes two separated coils for generating a magnetic field. An optimization process is carried out to achieve maximal damping force under certain design constraints, such as the allowable height of the mount. As an actuating smart fluid, a new plate-like iron-particle-based MR fluid is used, instead of the conventional spherical iron-particle-based MR fluid. After evaluating the field-dependent yield stress of the MR fluid, the field-dependent damping force required to control unwanted vibration in the ship engine is determined. Subsequently, an appropriate-sized MR mount is manufactured and its damping characteristics are evaluated. After confirming the sufficient damping force level of the manufactured MR mount, a medium-sized ship engine mount system consisting of eight MR mounts is established, and its dynamic governing equations are derived. A new modified indirect fuzzy sliding mode controller is then formulated and applied to the engine mount system. The displacement and velocity responses show that the unwanted vibrations of the ship engine system can be effectively controlled in both the axial and radial directions by applying the proposed control methodology.

  20. Integrated Vehicle Ground Vibration Testing in Support of NASA Launch Vehicle Loads and Controls Analysis (United States)

    Tuma, Margaret L.; Davis, Susan R.; Askins, Bruce R.; Salyer, Blaine H.


    The National Aeronautics and Space Administration (NASA) Ares Projects Office (APO) is continuing to make progress toward the final design of the Ares I crew launch vehicle and Ares V cargo launch vehicle. Ares I and V will form the space launch capabilities necessary to fulfill NASA's exploration strategy of sending human beings to the Moon, Mars, and beyond. As with all new space vehicles there will be a number of tests to ensure the design can be Human Rated. One of these is the Integrated Vehicle Ground Vibration Test (IVGVT) that will be measuring responses of the Ares I as a system. All structural systems possess a basic set of physical characteristics unique to that system. These unique characteristics include items such as mass distribution, frequency and damping. When specified, they allow engineers to understand and predict how a structural system like the Ares I launch vehicle behaves under given loading conditions. These physical properties of launch vehicles may be predicted by analysis or measured through certain types of tests. Generally, these properties are predicted by analysis during the design phase of a launch vehicle and then verified through testing before the vehicle is Human Rated. The IVGVT is intended to measure by test the fundamental dynamic characteristics of Ares I during various phases of operational/flight. This testing includes excitations of the vehicle in lateral, longitudinal, and torsional directions at vehicle configurations representing different trajectory points. During the series of tests, properties such as natural frequencies, mode shapes, and transfer functions are measured directly. These data will then be used to calibrate loads and Guidance, Navigation, and Controls (GN&C) analysis models for verifying analyses of Ares I. NASA launch vehicles from Saturn to Shuttle have undergone Ground Vibration Tests (GVTs) leading to successful launch vehicles. A GVT was not performed on the unmanned Delta III. This vehicle was

  1. Report on design and technical standard planning of vibration controlling structure on the buildings, in the Tokai Reprocessing Facility, Power Reactor and Nuclear Fuel Development Corporation

    Energy Technology Data Exchange (ETDEWEB)

    Uryu, Mitsuru; Terada, Shuji; Shinohara, Takaharu; Yamazaki, Toshihiko; Nakayama, Kazuhiko [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works; Kondo, Toshinari; Hosoya, Hisashi


    The Tokai reprocessing facility buildings are constituted by a lower foundation, vibration controlling layers, and upper structure. At the vibration controlling layer, a laminated rubber aiming support of the building load and extension of the eigenfrequency and a damper aiming absorption of earthquake energy are provided. Of course, the facility buildings are directly supported at the arenaceous shale (Taga Layer) of the Miocene in the Neogene confirmed to the stablest ground, as well the buildings with high vibration resistant importance in Japan. This report shows that when the vibration controlling structure is adopted for the reprocessing facility buildings where such high vibration resistance is required, reduction of input acceleration for equipments and pipings can be achieved and the earthquake resistant safety can also be maintained with sufficient tolerance and reliability. (G.K.)

  2. Hand-arm vibration syndrome. A double-blind case-control study with a new esthesiometer. (United States)

    Chatterjee, D S


    This double-blind case-control study on hand-arm vibration syndrome was sponsored by the Society of Occupation Medicine Golden Jubilee Travelling Scholarship Committee in 1987. It involved collaborative work between the author and the Department of Clinical Neurosciences, Institute of Occupational Health, Helsinki, Finland. The procedure consisted of administration of a questionnaire, clinical examination of subjects in the study group and depth-sense esthesiometry for all subjects including the controls. Of 34 subjects admitted to the study, 14 out of 15 patients were positively diagnosed as suffering from the syndrome and one out of 19 in the control group had a false positive result. The study showed that the new esthesiometer, although not totally objective, could be regarded as an effective tool for the diagnosis of hand-arm vibration syndrome in clinical and field studies.

  3. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part II: Experiment

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar


    mistuning, can easily be generated by substitution or rearranging the blades. Six sets of electro-magnetic actuators are applied to the system in order to control the blades as well as the rotor vibrations. Four sets of actuators are mounted in the rotating disc acting directly onto each one of the blades......This is the second paper in a two-part study on active rotor-blade vibration control. This part presents an experimental contribution into the work of active controller design for rotor-blade systems. The primary aim is to give an experimental validation and show the applicability...... of the theoretical results presented in part 1 of the study. A test rig of a coupled rotor-blade system, where blades flexible motion is coupled to rotor lateral motion, is build for the experimental research. The rig is build by four flexible blades radially attached onto a rotating rigid disc and shaft. The rigid...

  4. Vibration Control on Multilayer Cable Moving through the Crossover Zones on Mine Hoist

    National Research Council Canada - National Science Library

    Peng, Xia; Gong, Xian-sheng; Liu, Jin-jun


      Mine hoist is an important piece of equipment in mine hoist systems, and we achieve deep mine hoist through the multilayer winding, but the cable always undergoes severe shock and vibration during...

  5. Development of an Anti-Vibration Controller for Magnetic Bearing Cooling Systems Project (United States)

    National Aeronautics and Space Administration — This proposal outlines a program to develop a vibration-free reverse-Brayton cycle cooling system using specially-tuned magnetic bearings. Such a system is critical...

  6. Identification for Active Vibration Control of Flexible Structure Based on Prony Algorithm

    National Research Council Canada - National Science Library

    Sheng, Xianjun; Kong, Yuanli; Zhang, Fengyun; Yang, Rui


    .... The modal parameters and transfer function of the system are identified from the step response signal based on Prony algorithm, while the vibration is attenuated by using the input shaping technique...

  7. Early vibration assisted physiotherapy in toddlers with cerebral palsy - a randomized controlled pilot trial. (United States)

    Stark, C; Herkenrath, P; Hollmann, H; Waltz, S; Becker, I; Hoebing, L; Semler, O; Hoyer-Kuhn, H; Duran, I; Hero, B; Hadders-Algra, M; Schoenau, E


    to investigate feasibility, safety and efficacy of home-based side-alternating whole body vibration (sWBV) to improve motor function in toddlers with cerebral palsy (CP). Randomized controlled trial including 24 toddlers with CP (mean age 19 months (SD±3.1); 13 boys). 14 weeks sWBV with ten 9-minute sessions weekly (non-individualized). Group A started with sWBV, followed by 14 weeks without; in group B this order was reversed. Feasibility (≥70% adherence) and adverse events were recorded; efficacy evaluated with the Gross Motor Function Measure (GMFM-66), Pediatric Evaluation of Disability Inventory (PEDI), at baseline (T0), 14 (T1) and 28 weeks (T2). Developmental change between T0 and T1 was similar in both groups; change scores in group A and B: GMFM-66 2.4 (SD±2.1) and 3.3 (SD±2.9) (p=0.412); PEDI mobility 8.4 (SD±6.6) and 3.5 (SD±9.2) (p=0.148), respectively. In two children muscle tone increased post-sWBV. 24 children received between 67 and 140 sWBV sessions, rate of completed sessions ranged from 48 to 100% and no dropouts were observed. A 14-week home-based sWBV intervention was feasible and safe in toddlers with CP, but was not associated with improvement in gross motor function.

  8. Vibration Analysis and Models of Adjacent Structures Controlled by Magnetorheological Dampers

    Directory of Open Access Journals (Sweden)

    Michela Basili


    Full Text Available This paper deals with the vibration analysis of adjacent structures controlled by a magnetorheological (MR damper and with the discussion of a numerical procedure for identification and definition of a reliable finite element model. The paper describes an extensive experimental campaign investigating the dynamic response, through shaking table tests, of a tridimensional four-story structure and a two-story structure connected by an MR device. Several base excitations and intensity levels are considered. The structures were tested in nonconnected and connected configuration, with the MR damper operating in passive or semiactive mode. Moreover, the paper illustrates a procedure for the structural identification and the definition of a reliable numerical model valid for adjacent structures connected by MR dampers. The procedure is applied in the original nonconnected configuration, which represents a linear system, and then in the connected configuration, which represents a nonlinear system due to the MR damper. In the end, the updated finite element model is reliable and suitable for all the considered configurations and the mass, damping, and stiffness matrices are derived. The experimental and numerical responses are compared and the results confirm the effectiveness of the identification procedure and the validation of the finite element model.

  9. Phase-coexisting patterns, horizontal segregation, and controlled convection in vertically vibrated binary granular mixtures (United States)

    Ansari, Istafaul Haque; Rivas, Nicolas; Alam, Meheboob


    We report patterns consisting of coexistence of synchronous and asynchronous states [for example, a granular gas co-existing with (i) bouncing bed, (ii) undulatory subharmonic waves, and (iii) Leidenfrost-like states] in experiments on vertically vibrated binary granular mixtures in a Hele-Shaw cell. Most experiments have been carried out with equimolar binary mixtures of glass and steel balls of same diameter by varying the total layer height (F ) for a range of shaking acceleration (Γ ). All patterns as well as the related phase diagram in the (Γ ,F ) plane have been reproduced via molecular dynamics simulations of the same system. The segregation of heavier and lighter particles along the horizontal direction is shown to be the progenitor of such phase-coexisting patterns as confirmed in both experiment and simulation. At strong shaking we uncover a partial convection state in which a pair of convection rolls is found to coexist with a Leidenfrost-like state. The crucial role of the relative number density of two species on controlling the buoyancy-driven granular convection is demonstrated. The onset of horizontal segregation can be explained in terms of an anisotropic diffusion tensor.

  10. Vibration and Damping Analysis of Composite Fiber Reinforced Wind Blade with Viscoelastic Damping Control

    Directory of Open Access Journals (Sweden)

    Tai-Hong Cheng


    Full Text Available Composite materials are increasingly used in wind blade because of their superior mechanical properties such as high strength-to-weight and stiffness-to-weight ratio. This paper presents vibration and damping analysis of fiberreinforced composite wind turbine blade with viscoelastic damping treatment. The finite element method based on full layerwise displacement theory was employed to analyze the damping, natural frequency, and modal loss factor of composite shell structure. The lamination angle was considered in mathematical modeling. The curved geometry, transverse shear, and normal strains were exactly considered in present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The frequency response functions of curved composite shell structure and wind blade were calculated. The results show that the damping ratio of viscoelastic layer is found to be very sensitive to determination of magnitude of composite structures. The frequency response functions with variety of thickness of damping layer were investigated. Moreover, the natural frequency, modal loss factor, and mode shapes of composite fiber reinforced wind blade with viscoelastic damping control were calculated.

  11. Mastoid vibration affects dynamic postural control during gait in healthy older adults


    Jung Hung Chien; Mukul Mukherjee; Jenny Kent; Nicholas Stergiou


    Vestibular disorders are difficult to diagnose early due to the lack of a systematic assessment. Our previous work has developed a reliable experimental design and the result shows promising results that vestibular sensory input while walking could be affected through mastoid vibration (MV) and changes are in the direction of motion. In the present paper, we wanted to extend this work to older adults and investigate how manipulating sensory input through mastoid vibration (MV) could affect dy...

  12. Higher harmonic control analysis for vibration reduction of helicopter rotor systems (United States)

    Nguyen, Khanh Q.


    An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor

  13. Divison of Environmental Control Technology program, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Mott, William E.


    This report covers Division of Environmental Control Technology projects in progress during FY 1978, within the Office of the Assistant Secretary for Environment, Department of Energy. It is the second in a planned series of annual reports. The Division of Environmental Control Technology (ECT) continues to support the Assistant Secretary for Environment (EV) in discharging two primary responsibilities: (1) under the Environmental Engineering (EE) Program, the independent overview and assessment of environmental control aspects of both the U.S. Department of Energy's (DOE) research, development, and demonstration (RD and D) programs and the Nation's energy policies, and (2) under the Decontamination and Decommissioning Program, the reduction of potential environmental hazards at the radioactively contaminated sites that are presently owned or were formerly used by the Government. This report presents a short summary of objectives, approach, progress and results, future plans, and a reference bibliography for each research, development, or assessment project within the program areas described above.

  14. Feedback-controlled lubrication for reducing the lateral vibration of flexible rotors supported by tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar


    The feedback-controlled lubrication regime, based on a model-free designed proportional–derivative controller, is experimentally investigated in a flexible rotor mounted on an actively-lubricated tilting-pad journal bearing. With such a lubrication regime, both the resulting pressure distribution...... over the pads and hence the bearing dynamic properties are dynamically modified. The control strategy is focused on reducing the lateral vibrations of the system around its operational equilibrium within a wide frequency range. To synthesize the proportional–derivative controller gains, an objective...

  15. Coherent control of flexural vibrations in dual-nanoweb fibers using phase-modulated two-frequency light (United States)

    Koehler, J. R.; Noskov, R. E.; Sukhorukov, A. A.; Novoa, D.; Russell, P. St. J.


    Coherent control of the resonant response in spatially extended optomechanical structures is complicated by the fact that the optical drive is affected by the backaction from the generated phonons. Here we report an approach to coherent control based on stimulated Raman-like scattering, in which the optical pressure can remain unaffected by the induced vibrations even in the regime of strong optomechanical interactions. We demonstrate experimentally coherent control of flexural vibrations simultaneously along the whole length of a dual-nanoweb fiber, by imprinting steps in the relative phase between the components of a two-frequency pump signal, the beat frequency being chosen to match a flexural resonance. Furthermore, sequential switching of the relative phase at time intervals shorter than the lifetime of the vibrations reduces their amplitude to a constant value that is fully adjustable by tuning the phase modulation depth and switching rate. The results may trigger new developments in silicon photonics, since such coherent control uniquely decouples the amplitude of optomechanical oscillations from power-dependent thermal effects and nonlinear optical loss.

  16. Vibration perception threshold in relation to postural control and fall risk assessment in elderly. (United States)

    de Mettelinge, Tine Roman; Calders, Patrick; Palmans, Tanneke; Vanden Bossche, Luc; Van Den Noortgate, Nele; Cambier, Dirk


    This study investigates (i) the potential discriminative role of a clinical measure of peripheral neuropathy (PN) in assessing postural performance and fall risk and (ii) whether the integration of a simple screening vibration perception threshold (VPT) for PN in any physical (fall risk) assessment among elderly should be recommended, even if they do not suffer from DM. One hundred and ninety-five elderly were entered in a four-group model: DM with PN (D+; n = 75), DM without PN (D-; n = 28), non-diabetic elderly with idiopathic PN (C+; n = 31) and non-diabetic elderly without PN (C-; n = 61). Posturographic sway parameters were captured during different static balance conditions (AMTI AccuGait, Watertown, MA). VPT, fall data, Mini-Mental State Examination and Clock Drawing Test were registered. Two-factor repeated-measures ANOVA was used to compare between groups and across balance conditions. The groups with PN demonstrated a strikingly comparable, though bigger sway, and a higher prospective fall incidence than their peers without PN. The indication of PN, irrespective of its cause, interferes with postural control and fall incidence. The integration of a simple screening for PN (like bio-thesiometry) in any fall risk assessment among elderly is highly recommended. Implications for Rehabilitation The indication of peripheral neuropathy (PN), irrespective of its cause, interferes with postural control and fall incidence. Therefore, the integration of a simple screening for PN (like bio-thesiometry) in any fall risk assessment among elderly is highly recommended. It might be useful to integrate somatosensory stimulation in rehabilitation programs designed for fall prevention.

  17. Efficacy of Whole-Body Vibration Board Training on Strength in Athletes After Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Study. (United States)

    Costantino, Cosimo; Bertuletti, Silvia; Romiti, Davide


    To evaluate whether an 8-week whole-body vibration training program may improve recovery of knee flexion/extension muscular strength in athletes after arthroscopic anterior cruciate ligament (ACL) reconstruction. Randomized controlled trial. Single outpatient rehabilitation center. Thirty-eight female volleyball/basketball players (aged between 20 and 30), randomized into 2 treatment groups. During a standardized six-month rehabilitation program, from week 13 to week 20 after surgery, the whole-body vibration group (n = 19) and the control group (n = 19) performed additional static knee flexor/extensor exercises on a vibration platform. For the whole-body vibration group, the vibration platform was set to 2.5 mm of amplitude and 26 Hz of frequency. The control group followed the same whole-body vibration board training with no vibrations. All patients were evaluated using an isokinetic strength test with a Biodex dynamometer at the beginning and at the end of the additional treatment protocol. The parameters tested were the peak torque and the maximum power of knee flexor and extensor muscles performing strength and endurance tests. No vibration-related side effects were observed. Improvements were noticed in both groups, but increase in knee muscle isokinetic strength values was statistically significant in the whole-body vibration group when compared with the control group (differences in extension: peak torque 11.316/10.263 N·m and maximum power 13.684/11.211 W; flexion: peak torque 9.632/11.105 N·m and maximum power 10.158/9.474 W; P < 0.001). When combined with a standardized rehabilitation program, whole-body vibration may increase muscular strength and be an effective additional treatment option in the rehabilitation of athletes after ACL arthroscopic reconstruction.

  18. Adaptive wing and flow control technology (United States)

    Stanewsky, E.


    The development of the boundary layer and the interaction of the boundary layer with the outer “inviscid” flow field, exacerbated at high speed by the occurrence of shock waves, essentially determine the performance boundaries of high-speed flight. Furthermore, flight and freestream conditions may change considerably during an aircraft mission while the aircraft itself is only designed for multiple but fixed design points thus impairing overall performance. Consequently, flow and boundary layer control and adaptive wing technology may have revolutionary new benefits for take-off, landing and cruise operating conditions for many aircraft by enabling real-time effective geometry optimization relative to the flight conditions. In this paper we will consider various conventional and novel means of boundary layer and flow control applied to moderate-to-large aspect ratio wings, delta wings and bodies with the specific objectives of drag reduction, lift enhancement, separation suppression and the improvement of air-vehicle control effectiveness. In addition, adaptive wing concepts of varying complexity and corresponding aerodynamic performance gains will be discussed, also giving some examples of possible structural realizations. Furthermore, penalties associated with the implementation of control and adaptation mechanisms into actual aircraft will be addressed. Note that the present contribution is rather application oriented.

  19. Control technology in supply systems. Regelungstechnik in der Versorgungstechnik

    Energy Technology Data Exchange (ETDEWEB)

    Bach, H.; Baumgarth, S.; Forsch, K.; Reeker, J.; Krinninger, H.; Ruosch, E.; Schaefer, A.; Schiele, J.; Schroeder, H.; Treusch, W.


    The textbook presents the theoretical fundamentals and practical examples of control technology in supply systems. Practical examples of the fields of heating, air conditioning, and gas supply are presented in detail. The book comprises the following chapters: 1. Introduction to control technology; 2. steady state and time behaviour of control loop elements; 3. controlled systems; 4. control equipment; 5. control elements; 6. closed loops; 7. preset control; 8. meshed control loops; 9. digital control technology; 10. central control systems for supply systems of buildings; 11. examples of supply systems control.

  20. Effectiveness of Stationary Humans and Tuned Mass Dampers in Controlling Floor vibrations

    DEFF Research Database (Denmark)

    Pedersen, Lars


    damper) so as to ensure compliance with requirements related to human tolerance to vertical vibrations. However, the paper demonstrates that stationary humans themselves can provide a significant passive damping source due to dynamic interaction between the masses of the stationary humans...... a dynamic excitation generated by humans in motion. The vibration levels are compared with those expected if the else wise empty structures were fitted with a tuned mass damper so as to illustrate the effectiveness of the crowd in mitigating floor vibrations. Since a stationary crowd of people changes...... the dynamic characteristics of the floor which they occupy, the effectiveness of a potential tuned mass damper installation would also be influenced by the crowd's presence, and the paper quantifies the changes in damper effectiveness introduced in this way. From the results presented in the paper is would...

  1. Active Tuned Mass Dampers for Control of In-Plane Vibrations of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Fitzgerald, B.; Basu, Biswajit; Nielsen, Søren R.K.


    This paper investigates the use of active tuned mass dampers (ATMDs) for the mitigation of in-plane vibrations in rotating wind turbine blades. The rotating wind turbine blades with tower interaction represent time-varying dynamical systems with periodically varying mass, stiffness, and damping...... for this purpose, which considers the structural dynamics of the system and the interaction between in-plane and out-of-plane vibrations. Also, the interaction between the blades and the tower including the tuned mass dampers is considered. The wind turbine with tuned mass dampers was subjected to gravity...

  2. Controlling the partial coalescence of a droplet on a vertically vibrated bath. (United States)

    Gilet, T; Vandewalle, N; Dorbolo, S


    A method is proposed to stop the cascade of partial coalescences of a droplet laid on a liquid bath. The strategy consists of vibrating the bath in the vertical direction in order to keep small droplets bouncing. Since large droplets are not able to bounce, they partially coalesce until they reach a critical size. The system behaves as a low pass filter: droplets smaller than the critical size are selected. This size has been investigated as a function of the acceleration and the frequency of the bath vibration. Results suggest that the limit size for bouncing is related to the first mode of the droplet deformation.

  3. Multiple-source multiple-harmonic active vibration control of variable section cylindrical structures: A numerical study (United States)

    Liu, Jinxin; Chen, Xuefeng; Gao, Jiawei; Zhang, Xingwu


    Air vehicles, space vehicles and underwater vehicles, the cabins of which can be viewed as variable section cylindrical structures, have multiple rotational vibration sources (e.g., engines, propellers, compressors and motors), making the spectrum of noise multiple-harmonic. The suppression of such noise has been a focus of interests in the field of active vibration control (AVC). In this paper, a multiple-source multiple-harmonic (MSMH) active vibration suppression algorithm with feed-forward structure is proposed based on reference amplitude rectification and conjugate gradient method (CGM). An AVC simulation scheme called finite element model in-loop simulation (FEMILS) is also proposed for rapid algorithm verification. Numerical studies of AVC are conducted on a variable section cylindrical structure based on the proposed MSMH algorithm and FEMILS scheme. It can be seen from the numerical studies that: (1) the proposed MSMH algorithm can individually suppress each component of the multiple-harmonic noise with an unified and improved convergence rate; (2) the FEMILS scheme is convenient and straightforward for multiple-source simulations with an acceptable loop time. Moreover, the simulations have similar procedure to real-life control and can be easily extended to physical model platform.

  4. How exciton-vibrational coherences control charge separation in the photosystem II reaction center

    NARCIS (Netherlands)

    Novoderezhkin, V.I.; Romero Mesa, E.; van Grondelle, R.


    In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary

  5. Edgewise vibration control of wind turbine blades using roller and liquid dampers

    DEFF Research Database (Denmark)

    Zhang, Zili; Nielsen, Søren R.K.


    suppressing edgewise vibrations. The roller dampers are more volumetrically efficient due to the higher mass density of the steel comparing with the liquid. On the other hand, TLCDs have their advantage that it is easier to specify the optimum damping of the damper by changing the opening ratio of the orifice...


    Rizzi, S. A.


    The Vibration Pattern Imager (VPI) system was designed to control and acquire data from laser vibrometer sensors. The PC computer based system uses a digital signal processing (DSP) board and an analog I/O board to control the sensor and to process the data. The VPI system was originally developed for use with the Ometron VPI Sensor (Ometron Limited, Kelvin House, Worsley Bridge Road, London, SE26 5BX, England), but can be readily adapted to any commercially available sensor which provides an analog output signal and requires analog inputs for control of mirror positioning. VPI's graphical user interface allows the operation of the program to be controlled interactively through keyboard and mouse-selected menu options. The main menu controls all functions for setup, data acquisition, display, file operations, and exiting the program. Two types of data may be acquired with the VPI system: single point or "full field". In the single point mode, time series data is sampled by the A/D converter on the I/O board at a user-defined rate for the selected number of samples. The position of the measuring point, adjusted by mirrors in the sensor, is controlled via a mouse input. In the "full field" mode, the measurement point is moved over a user-selected rectangular area with up to 256 positions in both x and y directions. The time series data is sampled by the A/D converter on the I/O board and converted to a root-mean-square (rms) value by the DSP board. The rms "full field" velocity distribution is then uploaded for display and storage. VPI is written in C language and Texas Instruments' TMS320C30 assembly language for IBM PC series and compatible computers running MS-DOS. The program requires 640K of RAM for execution, and a hard disk with 10Mb or more of disk space is recommended. The program also requires a mouse, a VGA graphics display, a Four Channel analog I/O board (Spectrum Signal Processing, Inc.; Westborough, MA), a break-out box and a Spirit-30 board (Sonitech


    Directory of Open Access Journals (Sweden)


    Full Text Available The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The

  8. Control concept for piezo-based actuator-sensor-units for uniaxial vibration damping in machine tools


    Neugebauer, Reimund; Pagel, K.; Bucht, A; Wittstock, V.; Pappe, A.


    Additional piezo-based components in drive trains can significantly improve the dynamic behaviour of machine tools. In this article we present a piezo-based actuator-sensor-unit that is able to reduce uniaxial vibrations in ball screw driven feed axis of machine tools. A complex model of a feed axis including ASU was developed to design a controller. The control concept is based on the direct velocity feedback. A modular test bench was designed, assembled and investigated to verify the ASU's ...

  9. Lessons Learned on the Application of Vibration Absorbers for Enhanced Cannon Stabilization

    Directory of Open Access Journals (Sweden)

    Eric Kathe


    Full Text Available This paper will summarize the successful application of muzzle-end vibration absorbers to reduce cannon vibration. This technology constitutes a weapons stabilization approach that focuses on passive mechanical structural modification of the cannon, rather than relying upon an external control law to actively cancel vibrations. Challenges encountered during field testing, non-ideal behavior, and performance evaluation using digital signal processing will be highlighted.

  10. Viability Analysis of Waste Tires as Material for Rail Vibration and Noise Control in Modern Tram Track Systems

    Directory of Open Access Journals (Sweden)

    Caiyou Zhao


    Full Text Available This research study focused on the effect of using damping chamber elements made from waste tires on railway noise reduction. First, the energy absorption characteristics of damping chamber elements with various gradation combinations and compaction indices were measured in the laboratory using compression testing. The laboratory compression results demonstrated that the optimal gradation combination of damping chamber elements is as follows: the content of fine rubber particles is 10%, the content of coarse granules is 90%, and the optimal compaction index is 0.98. Next, the findings from the laboratory compression-test studies were used to produce damping chamber elements that were applied to a full-scale modern track model in the laboratory. The measurements of the dynamic properties indicated that the damping chamber elements could significantly reduce the vibration levels of the rail head. Finally, the damping chamber elements, which had been proven effective through laboratory dynamic tests, were widely applied to test rail sections in the field. The field tests demonstrated that damping chamber elements can significantly increase the track vibration decay rate in the frequency range of 200–10000 Hz. Therefore, damping chamber elements made from waste tires are able to control rail vibration and noise in modern tram track systems.

  11. Vibration control of a flexible transmission shaft by means of a squeeze-film damper: An experimental investigation (United States)

    Roberts, J. B.; Kaya, F.


    The effectiveness of a sealed squeeze-film damper, as a means of suppressing the vibration response of a rotating flexible power transmission shaft, has been studied experimentally. With the damper at an intermediate span position, comparisons have been made between the measured vibration response and corresponding theoretical predictions. At low speeds, up to a speed just beyond the first critical speed, the results indicated that the squeeze-film damper behaved linearly, with a frequency independent damping coefficient. This coefficient was found to be about four times the value predicted from conventional short-bearing lubrication theory. At higher rotational speeds there was evidence that the damping coefficient tended to increase with increasing rotational speed and complex non-linear behaviour was observed when the speed was about three times the first critical speed. Althouth quantitative prediction of the experimental rotor-bearing system response could not be obtained, at high rotational speeds, it was evident that the squeeze-film device could very adequately control the vibration response over a wide speed range, covering the first three critical speeds.

  12. A New Fuzzy Sliding Mode Controller with a Disturbance Estimator for Robust Vibration Control of a Semi-Active Vehicle Suspension System

    Directory of Open Access Journals (Sweden)

    Byung-Keun Song


    Full Text Available This paper presents a new fuzzy sliding mode controller (FSMC to improve control performances in the presence of uncertainties related to model errors and external disturbance (UAD. As a first step, an adaptive control law is designed using Lyapunov stability analysis. The control law can update control parameters of the FSMC with a disturbance estimator (DE in which the closed-loop stability and finite-time convergence of tracking error are guaranteed. A solution for estimating the compensative quantity of the impact of UAD on a control system and a set of solutions are then presented in order to avoid the singular cases of the fuzzy-based function approximation, increase convergence ability, and reduce the calculating cost. Subsequently, the effectiveness of the proposed controller is verified through the investigation of vibration control performances of a semi-active vehicle suspension system featuring a magnetorheological damper (MRD. It is shown that the proposed controller can provide better control ability of vibration control with lower consumed power compared with two existing fuzzy sliding mode controllers.

  13. Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects. (United States)

    Rice, David A; McNair, Peter J; Lewis, Gwyn N


    A consequence of knee joint osteoarthritis (OA) is an inability to fully activate the quadriceps muscles, a problem termed arthrogenic muscle inhibition (AMI). AMI leads to marked quadriceps weakness that impairs physical function and may hasten disease progression. The purpose of the present study was to determine whether γ-loop dysfunction contributes to AMI in people with knee joint OA. Fifteen subjects with knee joint OA and 15 controls with no history of knee joint pathology participated in this study. Quadriceps and hamstrings peak isometric torque (Nm) and electromyography (EMG) amplitude were collected before and after 20 minutes of 50 Hz vibration applied to the infrapatellar tendon. Between-group differences in pre-vibration torque were analysed using a one-way analysis of covariance, with age, gender and body mass (kg) as the covariates. If the γ-loop is intact, vibration should decrease torque and EMG levels in the target muscle; if dysfunctional, then torque and EMG levels should not change following vibration. One-sample t tests were thus undertaken to analyse whether percentage changes in torque and EMG differed from zero after vibration in each group. In addition, analyses of covariance were utilised to analyse between-group differences in the percentage changes in torque and EMG following vibration. Pre-vibration quadriceps torque was significantly lower in the OA group compared with the control group (P = 0.005). Following tendon vibration, quadriceps torque (P 0.299). Hamstrings torque and EMG amplitude were unchanged in both groups (all P > 0.204). The vibration-induced changes in quadriceps torque and EMG were significantly different between the OA and control groups (all P torque or EMG (all P > 0.554). γ-loop dysfunction may contribute to AMI in individuals with knee joint OA, partially explaining the marked quadriceps weakness and atrophy that is often observed in this population.

  14. Wireless communication technology for modular mechatronic controllers

    CSIR Research Space (South Africa)

    Bright, G


    Full Text Available to modular architecture. Communication technology allows for the systematic integration of mechatronics sub-systems in order to achieve complex integrated mechatronics system which would be difficult to achieve without the use of information technology (IT...

  15. Division of Environmental Control Technology program, 1977

    Energy Technology Data Exchange (ETDEWEB)



    Environmental engineering programs are reviewed for the following technologies; coal; petroleum and gas; oil shale; solar; geothermal and energy conservation; nuclear energy; and decontamination and decommissioning. Separate abstracts were prepared for each technology. (MHR)

  16. 40 CFR 725.422 - Physical containment and control technologies. (United States)


    ... technologies. 725.422 Section 725.422 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Exemptions for New Microorganisms § 725.422 Physical containment and control technologies. The manufacturer must meet all of the following criteria for physical containment and control technologies for any...

  17. Helicopter gust alleviation, attitude stabilization, and vibration alleviation using individual-blade-control through a conventional swash plate (United States)

    Ham, N. D.


    The novel active control system presented for helicopter rotor aerodynamic and aeroelastic problems involves the individual control of each blade in the rotating frame over a wide range of frequencies (up to the sixth harmonic of rotor speed). This Individual Blade Control (IBC) system controls blade pitch by means of broadband electrohydraulic actuators attached to the swash plate (in the case of three blades) or individually to each blade, using acceleratometer signals to furnish control commands to the actuators. Attention is given to IBC's application to blade lag, flapping, and bending dynamics. It is shown that gust alleviation, attitude stabilization, vibration alleviation, and air/ground resonance suppression, are all achievable with a conventional helicopter swash plate.

  18. Adaptive simultaneous motion and vibration control for a multi flexible-link mechanism with uncertain general harmonic disturbance (United States)

    Wang, Ji; Pi, Yangjun; Hu, Yumei; Zhu, Zhencai; Zeng, Lingbin


    In this paper, a new motion and vibration synthesized control system-a linear quadratic regulator/strain rate feedback controller (LQR/SRF) with adaptive disturbance attenuation is presented for a multi flexible-link mechanism subjected to uncertain harmonic disturbances with arbitrary frequencies and unknown magnitudes. In the proposed controller, nodal strain rates are introduced into the model of the multi flexible-link mechanism, based upon which a synthesized LQR controller where both rigid-body motion and elastic deformation are considered is designed. The uncertain harmonic disturbances would be canceled in the feedback loop by its approximated value which is computed online via an adaptive update law. Asymptotic stability of the closed-loop system is proved by the Lyapunov analysis. The effectiveness of the proposed controller is shown via simulation.

  19. Feedback-Controlled Lubrication for Reducing the Lateral Vibration of Flexible Rotors supported by Tilting-Pad Journal Bearings

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar


    In this work, the feedback-controlled lubrication regime, based on a model-free designed proportional-derivative (PD) controller, is studied and experimentally tested in a flexible rotor mounted on an actively-lubricated tilting-pad journal bearing (active TPJB). With such a lubrication regime......, both the resulting pressure distribution over the pads and hence the bearing dynamic properties are dynamically modified. The control strategy is focused on reducing the system lateral vibration around its operational equilibrium position in a wide frequency range. For this purpose, servovalves...... are used as actuators and the flexible rotor lateral movements as feedback control signals. To synthesise the PD controller gains an objective function is optimized in the stabilizing gain domain and then chosen from a subdomain imposed by the servovalves restrictions. The D-decomposition approach expanded...

  20. Influence of vibration modes on control system stabilization for space shuttle type vehicles (United States)

    Greiner, H. G.


    An investigation was made to determine the feasibility of using conventional autopilot techniques to stabilize the vibration modes at the liftoff flight condition for two space shuttle configurations. One configuration is called the dual flyback vehicle in which both the orbiter and booster vehicles have wings and complete flyback capability. The other configuration is called the solid motor vehicle win which the orbiter only has flyback. The results of the linear stability analyses for each of the vehicles are summarized.

  1. Recent developments in radiation field control technology

    Energy Technology Data Exchange (ETDEWEB)

    Wood, C.J. [Electric Power Research Institute, Palo Alto, CA (United States)


    The U.S. nuclear power industry has been remarkably successful in reducing worker radiation exposures over the past ten years. There has been over a fourfold reduction in the person-rem incurred for each MW.year of electric power generated: from 1.8 in 1980, to only 0.39 person-rems in 1991 and 1992. Preliminary data for 1993 are even lower: approximately 0.37 person-rem.MW.year. Despite this substantial improvement, challenges for the industry remain. Individual exposure limits have been tightened in ICRP 60 and there will be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts with be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts will be required to meet the industry goals for 1995. Reducing out-of-core radiation fields offer the best chance of continuing the downward trend in exposures. To assist utilities select the most economic technology for their specific plants, EPRI has published a manual capturing worldwide operating experience with radiation-field control techniques (TR-100265). No one method will suffice, but implementing suitable combinations from this collection will enable utilities to achieve their exposure goals. Radiation reduction is generally cost-effective: outages are shorter, manpower requirements are reduced and work quality is improved. Despite the up front costs, the benefits over the following 1-3 years typically outweigh the expenses.

  2. Controlling electron energy distributions for plasma technologies (United States)

    Kushner, Mark


    The basic function of low temperature plasmas in society benefiting technologies is to channel power into specific modes of atoms and molecules to excite desired states or produce specified radicals. This functionality ultimately depends on the ability to craft an electron energy distribution (EED) to match cross sections. Given electric fields, frequencies, gas mixtures and pressures, predicting EEDs and excitation rates can in large part be reliably done. The inverse problem, specifying the conditions that produce a given EED, is less well understood. Early strategies to craft EEDs include adjusting gas mixtures, such as the rare gas-Hg mixtures in fluorescent lamps, and externally sustained discharges, such as electron-beam sustained plasmas for molecular lasers. More recent strategies include spiker-sustainer circuitry which produces desired EEDs in non-self-sustained plasmas; and adjusting frequency in capacitively coupled plasmas. In this talk, past strategies for customizing EEDs in low pressure plasmas will be reviewed and prospects for improved control of plasma kinetics will be discussed using results from 2-dimensional computer models.

  3. A Review of Hybrid Fiber-Optic Distributed Simultaneous Vibration and Temperature Sensing Technology and Its Geophysical Applications

    Directory of Open Access Journals (Sweden)

    Khalid Miah


    Full Text Available Distributed sensing systems can transform an optical fiber cable into an array of sensors, allowing users to detect and monitor multiple physical parameters such as temperature, vibration and strain with fine spatial and temporal resolution over a long distance. Fiber-optic distributed acoustic sensing (DAS and distributed temperature sensing (DTS systems have been developed for various applications with varied spatial resolution, and spectral and sensing range. Rayleigh scattering-based phase optical time domain reflectometry (OTDR for vibration and Raman/Brillouin scattering-based OTDR for temperature and strain measurements have been developed over the past two decades. The key challenge has been to find a methodology that would enable the physical parameters to be determined at any point along the sensing fiber with high sensitivity and spatial resolution, yet within acceptable frequency range for dynamic vibration, and temperature detection. There are many applications, especially in geophysical and mining engineering where simultaneous measurements of vibration and temperature are essential. In this article, recent developments of different hybrid systems for simultaneous vibration, temperature and strain measurements are analyzed based on their operation principles and performance. Then, challenges and limitations of the systems are highlighted for geophysical applications.


    The Environmental Technology Verification report discusses the technology and performance of the Xonon Cool Combustion System manufactured by Catalytica Energy Systems, Inc., formerly Catalytica Combustion Systems, Inc., to control NOx emissions from gas turbines that operate wit...

  5. Vibration Isolation for Parallel Hydraulic Hybrid Vehicles

    Directory of Open Access Journals (Sweden)

    The M. Nguyen


    Full Text Available In recent decades, several types of hybrid vehicles have been developed in order to improve the fuel economy and to reduce the pollution. Hybrid electric vehicles (HEV have shown a significant improvement in fuel efficiency for small and medium-sized passenger vehicles and SUVs. HEV has several limitations when applied to heavy vehicles; one is that larger vehicles demand more power, which requires significantly larger battery capacities. As an alternative solution, hydraulic hybrid technology has been found effective for heavy duty vehicle because of its high power density. The mechanical batteries used in hydraulic hybrid vehicles (HHV can be charged and discharged remarkably faster than chemical batteries. This feature is essential for heavy vehicle hybridization. One of the main problems that should be solved for the successful commercialization of HHV is the excessive noise and vibration involving with the hydraulic systems. This study focuses on using magnetorheological (MR technology to reduce the noise and vibration transmissibility from the hydraulic system to the vehicle body. In order to study the noise and vibration of HHV, a hydraulic hybrid subsystem in parallel design is analyzed. This research shows that the MR elements play an important role in reducing the transmitted noise and vibration to the vehicle body. Additionally, locations and orientations of the isolation system also affect the efficiency of the noise and vibration mitigation. In simulations, a skyhook control algorithm is used to achieve the highest possible effectiveness of the MR isolation system.

  6. Life Cycle Cost Evaluation of Noise and Vibration Control Methods at Urban Railway Turnouts

    Directory of Open Access Journals (Sweden)

    Rodrigo Tavares de Freitas


    Full Text Available A focus of the railway industry over the past decades has been to research, find and develop methods to mitigate noise and vibration resulting from wheel/rail contact along track infrastructure. This resulted in a wide range of abatement measures that are available for today’s engineers. The suitability of each method must be analysed through budget and timeframe limitations, which includes building, maintenance and inspection costs and time allocation, while also aiming at delivering other benefits, such as environmental impact and durability of infrastructure. There are several situations that need noise and vibration mitigation methods, but each design allocates different priorities on a case-by-case basis. Traditionally, the disturbance caused by railways to the community are generated by wheel/rail contact sound radiation that is expressed in different ways, depending on the movement of the rolling stock and track alignment, such as rolling noise, impact noise and curve noise. More specifically, in special trackworks such as turnouts (or called “switches and crossings”, there are two types of noise that can often be observed: impact noise and screeching noise. With respect to the screeching (or flanging, its mitigation methods are usually associated with curve lubrications. In contrast, the impact noise emerges from the sound made by the rolling stock moving through joints and discontinuities (i.e., gaps, resulting in various noise abatement features to minimise such noise impact. Life cycle analysis is therefore vital for cost efficiency benchmarking of the mitigation methods. The evaluation is based on available data from open literature and the total costs were estimated from valid industry reports to maintain coherency. A 50-year period for a life cycle analysis is chosen for this study. As for the general parameters, an area with a high density of people is considered to estimate the values for a community with very strict limits

  7. Parameter Identification of Long Stroke and Short Stroke MR Damper for its Use in Semi-Active Vibration Control (United States)

    Bharathi Priya, C.; Gopalakrishnan, N.


    Magnetorheological (MR) dampers are devices that can be used for structural vibration reduction under seismic excitation. These devices are used in semi-active control which require less power compared to active devices and offer high reliability compared to passive devices. Despite the advantages of MR damper, use of these dampers in an effective way in a structure is highly challenging and a precise modelling is required as these dampers are highly non-linear. Among the parametric models available, Bouc-Wen model is widely used because of its effective modelling of the hysteretic force-velocity curve of MR damper. The parameters of Bouc-Wen model are damper dependent and hence need to be identified before utilising the damper for further simulation studies. In this work, the parametric identification of Bouc-Wen model for commercially available long stroke and short stroke MR damper (RD 8040-1 and RD 8041-1) is done. For this, experimental characterization of the dampers are carried out using hydraulic actuators mounted on a self-restraining frame. The damper is driven harmonically in the testing setup at various combinations of frequency, amplitude, current and displacement. Using the experimental characterization, parameters of Bouc-Wen model are identified by Levenberg-Marquardt optimization Algorithm (LMA). The identified parameters are validated by comparing with the experimental results. The identified parameters are believed to be worthwhile for the use of these MR dampers in further studies of real-time semi-active vibration control of structures.

  8. Simple Non-regenerative Deceleration Control of Permanent Magnetic Synchronous Motor for Vibration Control in Drum-type Washer/Dryer (United States)

    Tomigashi, Yoshio; Okonogi, Akira; Kishimoto, Keiji

    Drum-type washer/dryers are becoming more common in Japan, but the vibration created by unequally distributed clothes is a significant problem in this type of machine. We have developed a vibration control that prevents this imbalance by re-arranging the balancer fluid on the opposite side of the heavier distribution when there is unequal distribution. The drum, which has a large inertia, must be decelerated rapidly to enable the balancer fluid to shift. When a permanent magnetic synchronous motor is decelerated using an inverter, the machine's energy is converted into electrical energy, which regenerates the power supply. A control method has been developed that adjusts the input power of the motor to zero, thereby eliminating the need for a discharge circuit. However, it is not easy to achieve this method with an inexpensive microcomputer. In this paper, a practical braking method in which energy does not regenerate the power supply is examined. First, a simple method in which non-regenerative braking is possible with low input power is proposed, even though the input power is not zero. The effectiveness of this non-regenerative deceleration control is verified by theoretical numerical analysis and by an experiment. The borderline of the voltage vector for the non-generative braking is affected by dead time, and the experimental results differ from the theoretically calculated results. However, it is experimentally confirmed that the proposed non-regenerative deceleration control can be achieved by correcting the impressed voltage vector based on experimental results. Finally, this control is applied to the vibration control of the drum-type washer/dryer, and it is confirmed that the balancer fluid moves as designed.

  9. Alternative control technologies: Technologies de contrôle non conventionnelles

    National Research Council Canada - National Science Library

    Hudgins, Bernard


    .... Through different chapters, the various human factors issues related to the introduction of alternative control technologies into military cockpits are reviewed, in conjunction with more technical...

  10. A Robust Vibration Control of a Magnetorheological Damper Based Railway Suspension Using a Novel Adaptive Type 2 Fuzzy Sliding Mode Controller

    Directory of Open Access Journals (Sweden)

    Sy Dung Nguyen


    Full Text Available This work proposes a novel adaptive type 2 fuzzy sliding controller (AT2FC for vibration control of magnetorheological damper- (MRD- based railway suspensions subjected to uncertainty and disturbance (UAD. The AT2FC is constituted of four main parts. The first one is a sliding mode controller (SMC for specifying the main damping force supporting the suspension. This controller is designed via Lyapunov stability theory. The second one is an interpolation model based on an interval type 2 fuzzy logic system for determination of optimal parameters of the SMC. The third one is a nonlinear UAD observer to compensate for external disturbances. The fourth one is an inverse MRD model (T2F-I-MRD for specifying the input current. In the operating process, an adaptively optimal structure deriving from the SMC is created (called the Ad-op-SMC to adapt to the real status. Working as an actuator, the input current for MRD is then determined by the T2F-I-MRD to generate the required damping force which is estimated by the Ad-op-SMC and the nonlinear observer. It is shown that the obtained survey results reflect the AT2FC’s excellent vibration control performance compared with the other controllers.

  11. Active vibration control of a ring-stiffened cylindrical shell in contact with unbounded external fluid and subjected to harmonic disturbance by piezoelectric sensor and actuator (United States)

    Kwak, Moon K.; Yang, Dong-Ho


    This paper is concerned with the suppression of vibrations and radiated sound of a ring-stiffened circular cylindrical shell in contact with unbounded external fluid by means of piezoelectric sensors and actuators. The dynamic model of a circular cylindrical shell based on the Sanders shell theory was considered together with a ring stiffener model. The mass and stiffness matrices for a ring stiffener were newly derived in this study and added to the mass and stiffness matrices of the cylindrical shell, respectively. The fluid-added mass matrix, which was derived by using the baffled shell theory, was also added to the mass matrix. Finally, the equations representing the piezoelectric sensor measurement and piezoelectric actuation complete the theoretical model for the addressed problem. The natural vibration characteristics of the ring-stiffened cylindrical shell both in air and in water were investigated both theoretically and experimentally. The theoretical predictions were in good agreement with the experimental results. An active vibration controller which can cope with a harmonic disturbance was designed by considering the modified higher harmonic control, which is, in fact, a band rejection filter. An active vibration control experiment on the submerged cylindrical shell was carried out in a water tank and the digital control system was used. The experimental results showed that both vibrations and radiation sound of the submerged cylindrical shell were suppressed by a pair of piezoelectric sensor and actuator.

  12. Children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia: A randomized controlled trial. (United States)

    Bagherian, Ali; Sheikhfathollahi, Mahmood


    Topical anesthesia has been widely advocated as an important component of atraumatic administration of intraoral local anesthesia. The aim of this study was to use direct observation of children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia. Forty-eight children participated in this randomized controlled clinical trial. They received two separate inferior alveolar nerve block or primary maxillary molar infiltration injections on contralateral sides of the jaws by both cotton-roll vibration (a combination of topical anesthesia gel, cotton roll, and vibration for physical distraction) and control (routine topical anesthesia) methods. Behavioral pain reactions of children were measured according to the author-developed face, head, foot, hand, trunk, and cry (FHFHTC) scale, resulting in total scores between 0 and 18. The total scores on the FHFHTC scale ranged between 0-5 and 0-10 in the cotton-roll vibration and control methods, respectively. The mean ± standard deviation values of total scores on FHFHTC scale were lower in the cotton-roll vibration method (1.21 ± 1.38) than in control method (2.44 ± 2.18), and this was statistically significant (P anesthesia in reducing behavioral pain reactions in children during local anesthesia administration.

  13. Advanced Instrumentation, Information, and Control Systems Technologies Technical Program Plan

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Hallbert


    Reliable instrumentation, information, and control (II&C) systems technologies are essential to ensuring safe and efficient operation of the U.S. light water reactor (LWR) fleet. These technologies affect every aspect of nuclear power plant (NPP) and balance-of-plant operations. In 1997, the National Research Council conducted a study concerning the challenges involved in modernization of digital instrumentation and control systems in NPPs. Their findings identified the need for new II&C technology integration.

  14. Good vibrations? Vibrotactile self-stimulation reveals anticipation of body-related action effects in motor control. (United States)

    Pfister, Roland; Janczyk, Markus; Gressmann, Marcel; Fournier, Lisa R; Kunde, Wilfried


    Previous research suggests that motor actions are intentionally generated by recollecting their sensory consequences. Whereas this has been shown to apply to visual or auditory consequences in the environment, surprisingly little is known about the contribution of immediate, body-related consequences, such as proprioceptive and tactile reafferences. Here, we report evidence for a contribution of vibrotactile reafferences to action selection by using a response-effect compatibility paradigm. More precisely, anticipating actions to cause spatially incompatible vibrations delayed responding to a small but reliable degree. Whereas this observation suggests functional equivalence of body-related and environment-related reafferences to action control, the future application of the described experimental procedure might reveal functional peculiarities of specific types of sensory consequences in action control.

  15. Dynamic Responses and Vibration Control of the Transmission Tower-Line System: A State-of-the-Art Review (United States)

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping


    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

  16. Dynamic responses and vibration control of the transmission tower-line system: a state-of-the-art review. (United States)

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping


    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers.

  17. Case-control study of low-back pain referred for magnetic resonance imaging, with special focus on whole-body vibration. (United States)

    Palmer, Keith T; Harris, Clare E; Harris, E Claire; Griffin, Michael J; Bennett, James; Reading, Isabel; Sampson, Madelaine; Coggon, David


    This study investigated risk factors for low-back pain among patients referred for magnetic resonance imaging (MRI), with special focus on whole-body vibration. A case-control approach was used. The study population comprised working-aged persons from a catchment area for radiology services. The cases were those in a consecutive series referred for a lumbar MRI because of low-back pain. The controls were age- and gender-matched persons X-rayed for other reasons. Altogether, 252 cases and 820 controls were studied, including 185 professional drivers. The participants were questioned about physical factors loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about low-back pain. Exposure to whole-body vibration was assessed by six measures, including weekly duration of professional driving, hours driven in one period, and current root mean square A(8). Associations with whole-body vibration were examined with adjustment for age, gender, and other potential confounders. Strong associations were found with poor mental health and belief in work as a causal factor for low-back pain, and with occupational sitting for > or =3 hours while not driving. Associations were also found for taller stature, consulting propensity, body mass index, smoking history, fear-avoidance beliefs, frequent twisting, low decision latitude, and low support at work. However, the associations with the six metrics of whole-body vibration were weak and not statistically significant, and no exposure-response relationships were found. Little evidence of a risk from professional driving or whole-body vibration was found. Drivers were substantially less heavily exposed to whole-body vibration than in some earlier surveys. Nonetheless, it seems that, at the population level, whole-body vibration is not an important cause of low-back pain among those referred for MRI.

  18. Numerical and Experimental Characterizations of Damping Properties of SMAs Composite for Vibration Control Systems (United States)

    Biffi, Carlo Alberto; Bassani, P.; Tuissi, A.; Carnevale, M.; Lecis, N.; LoConte, A.; Previtali, B.


    Shape memory alloys (SMAs) are very interesting smart materials not only for their shape memory and superelastic effects but also because of their significant intrinsic damping capacity. The latter is exhibited upon martensitic transformations and especially in martensitic state. The combination of these SMA properties with the mechanical and the lightweight of fiberglass-reinforced polymer (FGRP) is a promising solution for manufacturing of innovative composites for vibration suppression in structural applications. CuZnAl sheets, after laser patterning, were embedded in a laminated composite between a thick FGRP core and two thin outer layers with the aim of maximizing the damping capacity of the beam for passive vibration suppression. The selected SMA Cu66Zn24Al10 at.% was prepared by vacuum induction melting; the ingot was subsequently hot-and-cold rolled down to 0.2 mm thickness tape. The choice of a copper alloy is related to some advantages in comparison with NiTiCu SMA alloys, which was tested for the similar presented application in a previous study: lower cost, higher storage modulus and consequently higher damping properties in martensitic state. The patterning of the SMA sheets was performed by means of a pulsed fiber laser. After the laser processing, the SMA sheets were heat treated to obtain the desired martensitic state at room temperature. The transformation temperatures were measured by differential scanning calorimetry (DSC). The damping properties were determined, at room temperature, on full-scale sheet, using a universal testing machine (MTS), with cyclic tensile tests at different deformation amplitudes. Damping properties were also determined as a function of the temperature on miniature samples with a dynamical mechanical analyzer (DMA). Numerical modeling of the laminated composite, done with finite element method analysis and modal strain energy approaches, was performed to estimate the corresponding total damping capacity and then

  19. The aircraft energy efficiency active controls technology program (United States)

    Hood, R. V., Jr.


    Broad outlines of the NASA Aircraft Energy Efficiency Program for expediting the application of active controls technology to civil transport aircraft are presented. Advances in propulsion and airframe technology to cut down on fuel consumption and fuel costs, a program for an energy-efficient transport, and integrated analysis and design technology in aerodynamics, structures, and active controls are envisaged. Fault-tolerant computer systems and fault-tolerant flight control system architectures are under study. Contracts with leading manufacturers for research and development work on wing-tip extensions and winglets for the B-747, a wing load alleviation system, elastic mode suppression, maneuver-load control, and gust alleviation are mentioned.

  20. Survey of multi-function display and control technology (United States)

    Spiger, R. J.; Farrell, R. J.; Tonkin, M. H.


    The NASA orbiter spacecraft incorporates a complex array of systems, displays and controls. The incorporation of discrete dedicated controls into a multi-function display and control system (MFDCS) offers the potential for savings in weight, power, panel space and crew training time. The technology applicable to the development of a MFDCS for orbiter application is surveyed. Technology thought to be applicable presently or in the next five years is highlighted. Areas discussed include display media, data handling and processing, controls and operator interactions and the human factors considerations which are involved in a MFDCS design. Several examples of applicable MFDCS technology are described.

  1. High force vibration testing with wide frequency range (United States)

    Romero, Edward F.; Jepsen, Richard A.; Gregory, Danny Lynn


    A shaker assembly for vibration testing includes first and second shakers, where the first shaker includes a piezo-electric material for generating vibration. A support structure permits a test object to be supported for vibration of the test object by both shakers. An input permits an external vibration controller to control vibration of the shakers.

  2. Application of Vortex Induced Vibration Energy Generation Technologies to the Offshore Oil and Gas Platform: The Preliminary Study


    M. A. Zahari; S. S. Dol


    The global demand for continuous and eco-friendly renewable energy as alternative to fossils fuels is large and ever growing in nowadays. This paper will focus on capability of Vortex Induced Vibration (VIV) phenomenon in generating alternative energy for offshore platform application. In order to maximize the potential of energy generation, the effects of lock in phenomenon and different geometries of cylinder were studied in this project. VIV is the motion induced on bl...

  3. Ultrasonic metal welding with a vibration source using longitudinal and torsional vibration transducers (United States)

    Asami, Takuya; Tamada, Yosuke; Higuchi, Yusuke; Miura, Hikaru


    Conventional ultrasonic metal welding for joining dissimilar metals uses a linear vibration locus, although this method suffers from problems such as low overall weld strength. Our previous studies have shown that ultrasonic welding with a planar vibration locus improves the weld strength. However, the vibration source in our previous studies had problems in longitudinal-torsional vibration controllability and small welding tip. Therefore, the study of the optimal shape of the vibration locus was difficult. Furthermore, improvement of weld strength cannot be expected. We have developed a new ultrasonic vibration source that can control the longitudinal-torsional vibration and can connect to a large welding tip. In this study, we clarified the longitudinal-torsional vibration controllability of the developed ultrasonic vibration source. Moreover, we clarified that using the planar locus of the developed vibration source produced a higher weld strength than our previous studies, and clarified the optimal shape of the vibration locus.

  4. Study protocol: the effect of whole body vibration on acute unilateral unstable lateral ankle sprain- a biphasic randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Baumbach Sebastian Felix


    Full Text Available Abstract Background Ankle sprains often result in ankle instability, which is most likely caused by damage to passive structures and neuromuscular impairment. Whole body vibration (WBV is a neuromuscular training method improving those impaired neurologic parameters. The aim of this study is to compare the current gold standard functional treatment to functional treatment plus WBV in patients with acute unilateral unstable inversion ankle sprains. Methods/Design 60 patients, aged 18–40 years, presenting with an isolated, unilateral, acute unstable inversion ankle sprain will be included in this bicentric, biphasic, randomized controlled trial. Samples will be randomized by envelope drawing. All patients will be allowed early mobilization and pain-dependent weight bearing, limited functional immobilization by orthosis, PRICE, NSARDs as well as home and supervised physiotherapy. Supervised physical therapy will take place twice a week, for 30 minutes for a period of 6 weeks, following a standardized intervention protocol. During supervised physical therapy, the intervention group will perform exercises similar to those of the control group, on a side-alternating sinusoidal vibration platform. Two time-dependent primary outcome parameters will be assessed: short-term outcome after six weeks will be postural control quantified by the sway index; mid-term outcome after one year will be assessed by subjective instability, defined by the presence of giving-way attacks. Secondary outcome parameters include: return to pre-injury level of activities, residual pain, recurrence, objective instability, energy/coordination, Foot and Ankle Disability Index and EQ 5D. Discussion This is the first trial investigating the effects of WBV in patients with acute soft tissue injury. Inversion ankle sprains often result in ankle instability, which is most likely due to damage of neurological structures. Due to its unique, frequency dependent, influence on various

  5. Controlling technology costs as integrated networks expand. (United States)

    Halverson, K


    The expansion of integrated healthcare networks is changing the way radiology technology should be acquired and maintained. Some significant effects are that utilization will decline with managed care; the radiology department is now a cost center, not a source of revenue; and integrated networks find themselves with redundant technology and excess radiology equipment. While hospitals shoulder additional financial risk associated with managed care, responsibility for finding solutions to new problems falls to the radiology administrator. Administrators can take the following steps to effectively reduce expense and risk: Understand current usage. Eliminate redundancies. Prioritize modalities. Find new financing opportunities. Lease equipment. Purchase reconditioned equipment. Redeploy assets instead of buying new. Radiology administrators who view these problems as a challenging puzzle will naturally explore creative options. They will provide the greatest flexibility and best position for their department's contributions to the hospital's overall strategic goals.

  6. Locus of Control and Technology Adoption in Developing Country Agriculture

    DEFF Research Database (Denmark)

    Abay, Kibrom Araya; Blalock, Garrick; Berhane, Guush


    adoption decisions, including use of chemical fertilizers, improved seeds, and irrigation. We show that individuals with an internal locus of control have higher propensity of adopting agricultural technologies. We observe these empirical regularities in both datasets, and for both revealed measures......We investigate the implication of farmers’ locus of control on their technology adoption decisions. Our empirical analysis is based on two longitudinal surveys and hypothetical choice exercises conducted on Ethiopian farmers. We find that locus of control significantly predicts farmers’ technology...... of farmers’ technology adoption decisions as well as farmers’ hypothetical demand for agricultural technology. The results hold even in a more conservative fixed effects estimation approach, assuming locus of control as time-variant and dynamic behavioral trait. These findings provide behavioral...

  7. Noise-control needs in the developing energy technologies

    Energy Technology Data Exchange (ETDEWEB)

    Keast, D.N.


    The noise characteristics of existing energy conversion technologies, e.g., from obtaining and processing fossil fuels to power plants operations, and of developing energy technologies (wind, geothermal sources, solar energy or fusion systems) are discussed in terms of the effects of noise on humans, animals, structures, and equipment and methods for noise control. Regulations for noise control are described. Recommendations are made for further research on noise control and noise effects. (LCL)

  8. Optimization of Sensing and Feedback Control for Vibration/Flutter of Rotating Disk by PZT Actuators via Air Coupled Pressure

    Directory of Open Access Journals (Sweden)

    Bingfeng Ju


    Full Text Available In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin’s discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

  9. Damage Control Technology - A Literature Review (United States)


    achieved. Options for smoke control on board ships have been reviewed126. Two series of tests127-128 have been completed that address the incorporation... Smoke Control Onboard Ships”, NRL Memorandum Report NRL/MR/6180--02-8612 of March 25, 2002. 127. Yadon, J.T., Havlovick, B.J., Farley, J.P. and Williams

  10. LNG fire and vapor control system technologies

    Energy Technology Data Exchange (ETDEWEB)

    Konzek, G.J.; Yasutake, K.M.; Franklin, A.L.


    This report provides a review of fire and vapor control practices used in the liquefied natural gas (LNG) industry. Specific objectives of this effort were to summarize the state-of-the-art of LNG fire and vapor control; define representative LNG facilities and their associated fire and vapor control systems; and develop an approach for a quantitative effectiveness evaluation of LNG fire and vapor control systems. In this report a brief summary of LNG physical properties is given. This is followed by a discussion of basic fire and vapor control design philosophy and detailed reviews of fire and vapor control practices. The operating characteristics and typical applications and application limitations of leak detectors, fire detectors, dikes, coatings, closed circuit television, communication systems, dry chemicals, water, high expansion foam, carbon dioxide and halogenated hydrocarbons are described. Summary descriptions of a representative LNG peakshaving facility and import terminal are included in this report together with typical fire and vapor control systems and their locations in these types of facilities. This state-of-the-art review identifies large differences in the application of fire and vapor control systems throughout the LNG industry.

  11. MFDC - technological improvement in resistance welding controls

    Energy Technology Data Exchange (ETDEWEB)

    Somani, A.K.; Naga Bhaskar, V.; Chandramouli, J.; Rameshwara Rao, A. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)


    Among the various Resistance Welding operations carried out in the production line of a fuel bundle end plug welding is the most critical operation. Welding controllers play a very vital role in obtaining consistent weld quality by regulating and controlling the weld current. Conventional mains synchronized welding controllers are at best capable of controlling the weld current at a maximum speed of the mains frequency. In view of the very short welding durations involved in the various stages of a fuel bundle fabrication, a need was felt for superior welding controllers. Medium Frequency Welding Controllers offer a solution to these limitations in addition to offering other advantages. Medium Frequency power sources offer precise welding current control as they regulate and correct the welding current faster, typically twenty times faster when operated at 1000Hz. An MFDC was employed on one of the welding machines and its performance was studied. This paper discusses about the various advantages of MFDCs with other controllers employed at NFC to end plug welding operation. (author)

  12. Mercury emissions control technologies for mixed waste thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Roberts, D.; Broderick, T. [ADA Technologies, Englewood, CO (United States)


    EPA has identified wet scrubbing at low mercury feedrates, as well as carbon adsorption via carbon injection into the offgas or via flow through fixed carbon beds, as control technologies that can be used to meet the proposed Maximum Achievable Control Technology (MACT) rule limit for mercury emissions from hazardous waste incinerators. DOE is currently funding demonstrations of gold amalgamation that may also control mercury to the desired levels. Performance data from a variety of sources was reviewed to determine ranges of achievable mercury control. Preliminary costs were estimated for using these technologies to control mercury emissions from mixed waste incineration. Mercury emissions control for mixed waste incineration may need to be more efficient than for incineration of other hazardous wastes because of higher mercury concentrations in some mixed waste streams. However, mercury control performance data for wet scrubbing and carbon adsorption is highly variable. More information is needed to demonstrate control efficiencies that are achievable under various design and operating conditions for wet scrubbing, carbon adsorption, and gold amalgamation technologies. Given certain assumptions made in this study, capital costs, operating costs, and lifecycle costs for carbon injection, carbon beds, and gold amalgamation generally vary for different assumed mercury feedrates and for different offgas flowrates. Assuming that these technologies can in fact provide the necessary mercury control performance, each of these technologies may be less costly than the others for certain mercury feedrates and the offgas flowrates.

  13. Hazards Control Department annual technology review, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, R.V.; Anderson, K.J. (eds.)


    This document describes some of the research performed in the LLNL Hazards Control Department from October 1986 to September 1987. The sections in the Annual report cover scientific concerns in the areas of Health Physics, Industrial Hygiene, Industrial Safety, Aerosol Science, Resource Management, Dosimetry and Radiation Physics, Criticality Safety, and Fire Science. For a broader overview of the types of work performed in the Hazards Control Department, we have also compiled a selection of abstracts of recent publications by Hazards Control employees. Individual reports are processed separately for the data base.

  14. Vibration Excitation and Control of a Pedestrian Walkway by Individuals and Crowds

    Directory of Open Access Journals (Sweden)

    James Mark William Brownjohn


    Full Text Available As part of a continuing study on effects of humans on loading and dynamic response of footbridges, a steel frame walkway has been the subject of studies on the effects of multiple pedestrians with respect to loading and response mitigation. Following finite element modeling and experimental modal analysis to identify the low frequency vibration modes likely to be excited by normal walking, the variation of response with pedestrian density and of system damping and natural frequency with occupancy by stationary pedestrians were both studied. The potentially mitigating effect of stationary occupants is still not well understood and the study included direct measurement of damping forces and absorbed energy using a force plate. The various tests showed that energy dissipation measured directly was consistent with the observed change in damping, that vertical and lateral response both varied approximately with square root of number of pedestrians, and that the simple model of a human as a single mass-spring-damper system may need to be refined to fit observed changes in modal parameters with a crowd of humans present. Modal parameter changes with moving pedestrians were small compared to those with stationary pedestrians indicating that within limits, modal parameters for the empty structure could be used in analysis.

  15. Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations. (United States)

    Manley, Michael E; Abernathy, Douglas L; Sahul, Raffi; Parshall, Daniel E; Lynn, Jeffrey W; Christianson, Andrew D; Stonaha, Paul J; Specht, Eliot D; Budai, John D


    Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 - x)[Pb(Mg1/3Nb2/3)O3] - xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening.

  16. Control means of the aerodynamic vibration occured in Parallel of PC cable-stayed bridge; PC shachokyo heiretsu keburu no taifu seishin taisaku to sono koka

    Energy Technology Data Exchange (ETDEWEB)

    Sato, H. [Public Works Research Inst., Tsukuba (Japan); Takeda, T.; Mukai, H. [Kajima Corp., Tokyo (Japan); Oikawa, K. [SE Corp., Tokyo (Japan)


    In recent years, the techniques for the typical PC bridges shown in the title have been considerably developed in Japan. However, occurrence of characteristic vibrations of the parallel cables even at relatively low wind speeds are observed in many cases, for which an effective control means is inevitably required. In this report, an investigation of tests on effectiveness of 4 kinds of vibration control means carried out in a wind tunnel and its results are described. In the test, an elastic model of 3-dimension was used for 5 test cases including a case without any control means, and each case was explained and examined in detail. It was revealed that for a damping system, a considerably large damping effect was necessary to restraint the wake galloping, and the cable distance selected to be 1.5 times smaller or 6 times larger than the cable diameter was effective, and while vibration control wires were effective, the adjustment of the cable vibration frequency was ineffective. It was also pointed out that a further verification would be necessary for the latter 2 control systems as no enough experience was yet accumulated in the actual service. 13 refs., 16 figs., 6 tabs.

  17. Simulation Study on Train-Induced Vibration Control of a Long-Span Steel Truss Girder Bridge by Tuned Mass Dampers

    Directory of Open Access Journals (Sweden)

    Hao Wang


    Full Text Available Train-induced vibration of steel truss bridges is one of the key issues in bridge engineering. This paper talks about the application of tuned mass damper (TMD on the vibration control of a steel truss bridge subjected to dynamic train loads. The Nanjing Yangtze River Bridge (NYRB is taken as the research object and a recorded typical train load is included in this study. With dynamic finite element (FE method, the real-time dynamic responses of NYRB are analyzed based on a simplified train-bridge time-varying system. Thereinto, two cases including single train moving at one side and two trains moving oppositely are specifically investigated. According to the dynamic characteristics and dynamic responses of NYRB, the fourth vertical bending mode is selected as the control target and the parameter sensitivity analysis on vibration control efficiency with TMD is conducted. Using the first-order optimization method, the optimal parameters of TMD are then acquired with the control efficiency of TMD, the static displacement of Midspan, expenditure of TMDs, and manufacture difficulty of the damper considered. Results obtained in this study can provide references for the vibration control of steel truss bridges.

  18. [A new program-controlled telemetry technology for pacemakers]. (United States)

    Wang, Yu; Huang, Xin-ming; Fang, Zu-xinag


    This thesis is about a new technology of program-controlled telemetry for pacemakers. The system utilizes digital logic circuit design, and the program-controlled part uses single chip to control for display and debug. PWM and reflectance telemetry may improve the preciseness and correctness of signal transmission, and reduce the power consumption of pacemakers and prolong the lifetime.

  19. Economics of selected water control technologies and their ...

    African Journals Online (AJOL)

    Marginal value products of farm inputs are found to be positive but their magnitudes differ by type of control structures, crop type, agro-ecology and regions. The net present values of all water control structures are positive. There is a favorable precondition for sustainable adoption of these controls technologies and ...

  20. Elastic optical networks architectures, technologies, and control

    CERN Document Server

    Velasco, Luis


    This book addresses challenges and potential solutions surrounding the dramatic yearly increases in bandwidth demand. The editors discuss the predicament surrounding current growth, which is predicted to continue because of the proliferation of disruptive, high bandwidth applications like video and cloud applications. They also discuss that in addition to growth, traffic will become much more dynamic, both in time and direction. The contributors show how large changes in traffic magnitude during a 24-hour period can be observed, as day-time business users have very different demands to evening-time residential customers, and how this plays into addressing future challenges. In addition, they discuss potential solutions for the issues surrounding situations where multiple content and cloud service providers offer competing services, causing the traffic direction to become more dynamic. The contributors discuss that although the WDM transponder technology can be upgraded to 100Gb/s in the short to medium term, ...

  1. Target-Controlled Infusion : A Mature Technology

    NARCIS (Netherlands)

    Absalom, Anthony R.; Glen, John (Iain) B.; Zwart, Gerrit J. C.; Schnider, Thomas W.; Struys, Michel M. R. F.

    Target-controlled infusions (TCIs) have been used in research and clinical practice for >2 decades. Nonapproved TCI software systems have been used during the conduct of almost 600 peer-reviewed published studies involving large numbers of patients. The first-generation pumps were first approved in

  2. Systematic approach to balanced control technology management

    Directory of Open Access Journals (Sweden)

    I. N. Vorobjev


    Full Text Available Articulated understanding of important systemic controls that exist in the modern world. Identify and describe the key success factors of a balanced management of organizational change. Proposed register of compliance balanced scorecard target values and objectives of balanced management of industrial organizations.

  3. Numerical simulation of intelligent compaction technology for construction quality control. (United States)


    Intelligent compaction (IC) technique is a fast-developing technology for compaction quality control and acceptance. Proof rolling using the intelligent compaction rollers after completing compaction can eectively identify : the weak spots and sig...

  4. Ethylene Production Maximum Achievable Control Technology (MACT) Compliance Manual (United States)

    This July 2006 document is intended to help owners and operators of ethylene processes understand and comply with EPA's maximum achievable control technology standards promulgated on July 12, 2002, as amended on April 13, 2005 and April 20, 2006.


    Directory of Open Access Journals (Sweden)

    A. E. Nikiforov


    Full Text Available The modern technologies of the enterprise control help to make the process of taking decisions more correct and reasonable, promote better understanding of real situations and appropriate response to them.

  6. Applications of aerospace technology in industry, a technology transfer profile: Contamination control (United States)


    The strong influence NASA-sponsored research has had on the development of solutions to difficult contamination problems is considered. The contamination control field is comprised of an industrial base, supplying the tools of control; a user base, adopting control techniques; and a technical base, expanding the concepts of control. Both formal and informal mechanisms used by NASA to communicate a variety of technical advances are reviewed and certain examples of the expansion of the user base through technology transfer are given. Issues related to transfer of NASA-generated contamination control technology are emphasized.

  7. Effectiveness of an Occupational Health Intervention Program to Reduce Whole Body Vibration Exposure: An Evaluation Study With a Controlled Pretest-Post-test Design

    NARCIS (Netherlands)

    Tiemessen, Ivo J. H.; Hulshof, Carel T. J.; Frings-Dresen, Monique H. W.


    Background An effective intervention program aiming to reduce whole body vibration (WBV) exposure at work will reduce the number of low back complaints in the near future. Methods An evaluation study with a controlled pretest-post-test design. Nine companies and 126 drivers were included in the

  8. International Conference on Systems, Control and Information Technologies 2016

    CERN Document Server

    Kaliczyńska, Małgorzata


    This book presents the proceedings of the International Conference on Systems, Control and Information Technologies 2016. It includes research findings from leading experts in the fields connected with INDUSTRY 4.0 and its implementation, especially: intelligent systems, advanced control, information technologies, industrial automation, robotics, intelligent sensors, metrology and new materials. Each chapter offers an analysis of a specific technical problem followed by a numerical analysis and simulation as well as the implementation for the solution of a real-world problem.

  9. Review of fluid and control technology of hydraulic wind turbines (United States)

    Cai, Maolin; Wang, Yixuan; Jiao, Zongxia; Shi, Yan


    This study examines the development of the fluid and control technology of hydraulic wind turbines. The current state of hydraulic wind turbines as a new technology is described, and its basic fluid model and typical control method are expounded by comparing various study results. Finally, the advantages of hydraulic wind turbines are enumerated. Hydraulic wind turbines are expected to become the main development direction of wind turbines.

  10. Effect of whole-body vibration on neuromuscular performance and body composition for females 65 years and older: a randomized-controlled trial. (United States)

    von Stengel, S; Kemmler, W; Engelke, K; Kalender, W A


    We examined whether the effect of multipurpose exercise can be enhanced by whole-body vibration (WBV). One hundred and fifty-one post-menopausal women (68.5 ± 3.1 years) were randomly assigned to three groups: (1) a training group (TG); (2) training including vibration (VTG); and (3) a wellness control group (CG). TG and VTG performed the same training program twice weekly (60 min), consisting of aerobic and strength exercises, with the only difference that leg strength exercises (15 min) were performed with (VTG) or without (TG) vibration. CG performed a low-intensity "wellness" program. At baseline and after 18 months, body composition was determined using dual-X-ray-absorptiometry. Maximum isometric strength was determined for the legs and the trunk region. Leg power was measured by countermovement jumps using a force-measuring plate. In the TG lean body mass, total body fat, and abdominal fat were favorably affected, but no additive effects were generated by the vibration stimulus. However, concerning muscle strength and power, there was a tendency in favor of the VTG. Only vibration training resulted in a significant increase of leg and trunk flexion strength compared with CG. In summary, WBV embedded in a multipurpose exercise program showed minor additive effects on body composition and neuromuscular performance. © 2010 John Wiley & Sons A/S.

  11. Analysis of a Battery Management System (BMS Control Strategy for Vibration Aged Nickel Manganese Cobalt Oxide (NMC Lithium-Ion 18650 Battery Cells

    Directory of Open Access Journals (Sweden)

    Thomas Bruen


    Full Text Available Electric vehicle (EV manufacturers are using cylindrical format cells as part of the vehicle’s rechargeable energy storage system (RESS. In a recent study focused at determining the ageing behavior of 2.2 Ah Nickel Manganese Cobalt Oxide (NMC Lithium-Ion 18650 battery cells, significant increases in the ohmic resistance (RO were observed post vibration testing. Typically a reduction in capacity was also noted. The vibration was representative of an automotive service life of 100,000 miles of European and North American customer operation. This paper presents a study which defines the effect that the change in electrical properties of vibration aged 18650 NMC cells can have on the control strategy employed by the battery management system (BMS of a hybrid electric vehicle (HEV. It also proposes various cell balancing strategies to manage these changes in electrical properties. Subsequently this study recommends that EV manufacturers conduct vibration testing as part of their cell selection and development activities so that electrical ageing characteristics associated with road induced vibration phenomena are incorporated to ensure effective BMS and RESS performance throughout the life of the vehicle.

  12. Siemens: Smart Technologies for Large Control Systems

    CERN Multimedia

    CERN. Geneva; BAKANY, Elisabeth


    The CERN Large Hadron Collider (LHC) is known to be one of the most complex scientific machines ever built by mankind. Its correct functioning relies on the integration of a multitude of interdependent industrial control systems, which provide different and essential services to run and protect the accelerators and experiments. These systems have to deal with several millions of data points (e.g. sensors, actuators, configuration parameters, etc…) which need to be acquired, processed, archived and analysed. Since more than 20 years, CERN and Siemens have developed a strong collaboration to deal with the challenges for these large systems. The presentation will cover the current work on the SCADA (Supervisory Control and Data Acquisition) systems and Data Analytics Frameworks.

  13. A Survey of Aircraft Integrated Control Technology. (United States)


    Airlines, Library Qantas Airways Limited Ansett Airlines of Australia, Library Hawker de Havilland Aust Pty Ltd, Victoria, Library Hawker de Havilland Aust...inherent control performance limitations imposed by the nature of the physical plant, and 4) lack of attention to the effects of uncertainty in the...Its disadvantages are a limited resolution in both range and angle and glint. It has good long range capability and is adaptable to detection of moving

  14. Technology research for digital flight control (United States)

    Carestia, R. A.


    The use of advanced digital systems for flight control and guidance for a specific mission is investigated. The research areas include advanced electronic system architectures, tests with the global positioning system (GPS) in a helicopter, and advanced integrated systems concept for rotorcraft. Emphasis is on a search and rescue mission, differential global positioning systems to provide a data base of performance information for navigation, and a study to determine the present usage and trends of microcomputers and microcomputer components in the avionics industries.

  15. Gun control : military technology aids production

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, L.


    The GasGun is a radial fracturing technology based on propellants used in large-bore guns during the Second World War. The patented GasGun is a military-grade propellant that is compatible with pen and cased hole completions. The device consists of perforated progressive-burning grains. The gun generates high-pressure gas at rates fast enough to create multiple fractures radiating between 10 to 50 feet from the wellbore. The device is conveyed to the formation in a high-strength, hollow steel carrier under a fluid column of between 300 to 8000 feet. A minimum 100 metre cushion of fluid is then placed above the gun. Gas exits the carrier and goes into the wellbore where it enters all perforating tunnels and creates radial fractures. Operators who have used the gun claim that it is both easy to use and cost-effective. It was concluded that the gun can offer significant savings when compared with traditional hydraulic fracturing treatments. 2 figs.

  16. Development of Plant Control Diagnosis Technology and Increasing Its Applications (United States)

    Kugemoto, Hidekazu; Yoshimura, Satoshi; Hashizume, Satoru; Kageyama, Takashi; Yamamoto, Toru

    A plant control diagnosis technology was developed to improve the performance of plant-wide control and maintain high productivity of plants. The control performance diagnosis system containing this technology picks out the poor performance loop, analyzes the cause, and outputs the result on the Web page. Meanwhile, the PID tuning tool is used to tune extracted loops from the control performance diagnosis system. It has an advantage of tuning safely without process changes. These systems are powerful tools to do Kaizen (continuous improvement efforts) step by step, coordinating with the operator. This paper describes a practical technique regarding the diagnosis system and its industrial applications.

  17. Freezing vibrational energy flow: a fitness function for interchangeable computational and experimental control. (United States)

    Weidinger, D; Engel, M F; Gruebele, M


    We develop a fitness functional for freezing molecular energy flow that relies only on experimental observables. The functional allows us to implement a modular control algorithm where simulation data and experimental data can be used interchangeably. This interchangeability could be useful as a spectroscopic tool and for reactive control because the controllability of the experimental system and its model can be compared directly. The fitness functional performs as well as functionals based on complete knowledge of the wave function. We compare our simulation results with an analytical theory of control, and find good agreement between the simulated and predicted times over which the system can be controlled.

  18. Automatic process control in anaerobic digestion technology: A critical review. (United States)

    Nguyen, Duc; Gadhamshetty, Venkataramana; Nitayavardhana, Saoharit; Khanal, Samir Kumar


    Anaerobic digestion (AD) is a mature technology that relies upon a synergistic effort of a diverse group of microbial communities for metabolizing diverse organic substrates. However, AD is highly sensitive to process disturbances, and thus it is advantageous to use online monitoring and process control techniques to efficiently operate AD process. A range of electrochemical, chromatographic and spectroscopic devices can be deployed for on-line monitoring and control of the AD process. While complexity of the control strategy ranges from a feedback control to advanced control systems, there are some debates on implementation of advanced instrumentations or advanced control strategies. Centralized AD plants could be the answer for the applications of progressive automatic control field. This article provides a critical overview of the available automatic control technologies that can be implemented in AD processes at different scales. Copyright © 2015 Elsevier Ltd. All rights reserved.


    Energy Technology Data Exchange (ETDEWEB)

    B.S. Turk; T. Merkel; A. Lopez-Ortiz; R.P. Gupta; J.W. Portzer; G.N. Krishnan; B.D. Freeman; G.K. Fleming


    The overall objective of this project is to develop technologies for cleaning/conditioning the syngas from an integrated gasification combined cycle (IGCC) system to meet the tolerance limits for contaminants such as H{sub 2}S, COS, NH{sub 3}, HCN, HCl, and alkali for fuel cell and chemical production applications. RTI's approach is to develop a modular system that (1) removes reduced sulfur species to sub-ppm levels using a hybrid process consisting of a polymer membrane and a regenerable ZnO-coated monolith or a mixed metal oxide sorbent; (2) removes hydrogen chloride vapors to sub-ppm levels using an inexpensive, high-surface area material; and (3) removes NH{sub 3} with acidic adsorbents. RTI is working with MEDAL, Inc., and North Carolina State University (NCSU) to develop polymer membrane technology for bulk removal of H{sub 2}S from syngas. These membranes are being engineered to remove the acid gas components (H{sub 2}S, CO{sub 2}, NH{sub 3}, and H{sub 2}O) from syngas by focusing on the ''solubility selectivity'' of the novel polymer compositions. The desirable components of the syngas (H{sub 2} and CO) are maintained at high-pressure conditions as a non-permeate stream while the impurities are transported across the membrane to the low pressure side. RTI tested commercially available and novel materials from MEDAL using a high-temperature, high-pressure (HTHP) permeation apparatus. H{sub 2}S/H{sub 2} selectivities >30 were achieved, although there was a strong negative dependence with temperature. MEDAL believes that all the polymer compositions tested so far can be prepared as hollow fiber membrane modules using the existing manufacturing technology. For fuel cell and chemical applications, additional sulfur removal (beyond that achievable with the membranes) is required. To overcome limitations of conventional ZnO pellets, RTI is testing a monolith with a thin coating of high surface area zinc-oxide based materials

  20. Lateral vibration control of a flexible overcritical rotor via an active gas bearing – Theoretical and experimental comparisons

    DEFF Research Database (Denmark)

    Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar


    The lack of damping of radial gas bearings leads to high vibration levels of a rotor supported by this type of bearing when crossing resonant areas. This is even more relevant for flexible rotors, as studied in this work. In order to reduce these high vibration levels, an active gas bearing is pr...

  1. Monitoring vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Tiryaki, B. [Hacettepe University (Turkey). Dept. of Mining Engineering


    The paper examines the prediction and optimisation of machine vibrations in longwall shearers. Underground studies were carried out at the Middle Anatolian Lignite Mine, between 1993 and 1997. Several shearer drums with different pick lacing arrangements were designed and tested on double-ended ranging longwall shearers employed at the mine. A computer program called the Vibration Analysis Program (VAP) was developed for analysing machine vibrations in longwall shearers. Shearer drums that were tested underground, as well as some provided by leading manufacturers, were analyzed using these programs. The results of the experiments and computer analyses are given in the article. 4 refs., 9 figs.

  2. Integrated Tools for Future Distributed Engine Control Technologies (United States)

    Culley, Dennis; Thomas, Randy; Saus, Joseph


    Turbine engines are highly complex mechanical systems that are becoming increasingly dependent on control technologies to achieve system performance and safety metrics. However, the contribution of controls to these measurable system objectives is difficult to quantify due to a lack of tools capable of informing the decision makers. This shortcoming hinders technology insertion in the engine design process. NASA Glenn Research Center is developing a Hardware-inthe- Loop (HIL) platform and analysis tool set that will serve as a focal point for new control technologies, especially those related to the hardware development and integration of distributed engine control. The HIL platform is intended to enable rapid and detailed evaluation of new engine control applications, from conceptual design through hardware development, in order to quantify their impact on engine systems. This paper discusses the complex interactions of the control system, within the context of the larger engine system, and how new control technologies are changing that paradigm. The conceptual design of the new HIL platform is then described as a primary tool to address those interactions and how it will help feed the insertion of new technologies into future engine systems.

  3. Experiments on active control of vibrational power flow using piezoceramic actuators and sensors (United States)

    Gibbs, Gary P.; Fuller, Chris R.


    The active control of flexural power flow in both semiinfinite and finite elastic beams is experimentally investigated. The experimental results demonstrate that piezoceramic transducers when used in conjunction with an adaptive least mean squares controller, can effectively control flexural power flow in thin beam systems. The piezoceramic transducers offer distinct size and weight advantages over conventional transducers. The experiments also demonstrate the use of an axial scanning laser vibrometer to determine out of plane velocity and power flow.

  4. Control at a distance as self-control: the renewal of the myth of control through technology


    Dambrin, Claire


    This paper draws on socio-institutional research on accounting technology. It underlines the ability of one type of accounting technology (performance measurement technology) to be a base for control at a distance since this technology links together discourse and calculation.

  5. Local distributed estimation. [for flexible spacecraft vibration mode optimal feedback control (United States)

    Schaechter, D. B.


    Based on partial differential equations of motion the closed form solution for the optimal estimation of a spatially continuous state vector is derived, using a continuously distributed sensor. Local control is shown to be the feedback that minimizes a quadratic performance index of sensor and process disturbances. A detailed example of the control of a string in tension is presented.

  6. Vibration Attenuation of Magnetorheological Landing Gear System with Human Simulated Intelligent Control

    Directory of Open Access Journals (Sweden)

    X. M. Dong


    Full Text Available Due to the short duration of impulsive impact of an aircraft during touchdown, a traditional landing gear can only achieve limited performance. In this study, a magnetorheological (MR absorber is incorporated into a landing gear system; an intelligent control algorithm, a human simulated intelligent control (HSIC, is proposed to adaptively tune the MR absorber. First, a two degree-of-freedom (DOF dynamic model of a landing gear system featuring an MR absorber is constructed. The control model of an MR damper is also developed. After analyzing the impact characteristic during touchdown, an HSIC is then formulated. A genetic algorithm is adopted to optimize the control parameters of HSIC. Finally, a numerical simulation is performed to validate the proposed damper and the controller considering the varieties of sink velocities and sprung masses. The simulations under different scenarios show that the landing gear system based on the MR absorber can greatly reduce the peak impact load of sprung mass within the stroke. The biggest improvement of the proposed controller is over 40% compared to that of skyhook controller. Furthermore, HSIC exhibits better adaptive ability and strong robustness than skyhook controller under various payloads and sink velocities.

  7. Non-resonant dynamic stark control of vibrational motion with optimized laser pulses

    DEFF Research Database (Denmark)

    Thomas, Esben Folger; Henriksen, Niels Engholm


    The term dynamic Stark control (DSC) has been used to describe methods of quantum control related to the dynamic Stark effect, i.e., a time-dependent distortion of energy levels. Here, we employ analytical models that present clear and concise interpretations of the principles behind DSC. Within ...

  8. A Study of Deadbeat Terminal Control for High Speed Low Vibration Robots (United States)


    34Mutivariable Dead-Beat Control," Automatica. Vol. 13, 1977, pp. 185-188. 6. F. Kucera , "The Structure and Properties of Time-Optimal Discrete Linear...Vol. AC-29, No. 1, Jan . 1984, pp. 77-79. 10. G. Klein, "The Structure and Freedom in Selecting Deadbeat Controllers," 11. Y. Takahashi, M. Rabins, and

  9. Nonlinear dynamics and control strategies: On a energy harvester vibrating system with a linear form to non-ideal motor torquet

    Directory of Open Access Journals (Sweden)

    de Pontes B. R.


    Full Text Available In this paper, we deal with the research of a vibrating model of an energy harvester device, including the nonlinearities in the model of the piezoelectric coupling and the non-ideal excitation. We show, using numerical simulations, in the analysis of the dynamic responses, that the harvested power is influenced by non-linear vibrations of the structure. Chaotic behavior was also observed, causing of the loss of energy throughout the simulation time. Using a perturbation technique, we find an approximate analytical solution for the non-ideal system. Then, we apply both two control techniques, to keep the considered system, into a stable condition. Both the State Dependent Ricatti Equation (SDRE control as the feedback control by changing the energy of the oscillator, were efficient in controlling of the considered non-ideal system.

  10. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar


    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... with experiment, and simulations show the feasibility of controlling shaft vibration through this active device....

  11. Evaluation of an occupational health intervention programme on whole‐body vibration in forklift truck drivers: a controlled trial (United States)

    Hulshof, C T J; Verbeek, J H A M; Braam, I T J; Bovenzi, M; van Dijk, F J H


    Objectives To evaluate process and outcome of a multifaceted occupational health intervention programme on whole‐body vibration (WBV) in forklift truck drivers. Methods An experimental pretest/post‐test control group study design. The authors trained occupational health services (OHS) in the experimental group in the use of the programme. OHS in the control group were asked to deliver care as usual. In total, 15 OHS, 32 OHS professionals, 26 companies, and 260 forklift drivers were involved. Post‐test measurements were carried out one year after the start of the programme. Results Baseline data before the start of the programme showed no difference between experimental and control group. Results of the outcome evaluation indicate a slight, although not statistically significant, reduction of WBV exposure in the experimental group (p = 0.06). Process evaluation revealed a positive influence on company policy toward WBV, attitude and intended behaviour of forklift drivers, and a trend towards an increase in knowledge of OHS professionals and company managers. The number of observed control measures with a major impact (levelling of surface and reduction of speed) was rather low. In those cases where control measures had been taken, there was a significant reduction in WBV exposure. This limited effect of the programme might be caused by the short period of follow up and the dropout of participants. The feasibility and the usefulness of the programme within the OHS setting were rated good by the participants. Conclusions This programme to decrease WBV exposure was partially effective. Significant effects on intermediate objectives were observed. More research on the effectiveness of intervention in the field of WBV is needed. PMID:16551762

  12. Evaluation of an occupational health intervention programme on whole-body vibration in forklift truck drivers: a controlled trial. (United States)

    Hulshof, C T J; Verbeek, J H A M; Braam, I T J; Bovenzi, M; van Dijk, F J H


    To evaluate process and outcome of a multifaceted occupational health intervention programme on whole-body vibration (WBV) in forklift truck drivers. An experimental pretest/post-test control group study design. The authors trained occupational health services (OHS) in the experimental group in the use of the programme. OHS in the control group were asked to deliver care as usual. In total, 15 OHS, 32 OHS professionals, 26 companies, and 260 forklift drivers were involved. Post-test measurements were carried out one year after the start of the programme. Baseline data before the start of the programme showed no difference between experimental and control group. Results of the outcome evaluation indicate a slight, although not statistically significant, reduction of WBV exposure in the experimental group (p = 0.06). Process evaluation revealed a positive influence on company policy toward WBV, attitude and intended behaviour of forklift drivers, and a trend towards an increase in knowledge of OHS professionals and company managers. The number of observed control measures with a major impact (levelling of surface and reduction of speed) was rather low. In those cases where control measures had been taken, there was a significant reduction in WBV exposure. This limited effect of the programme might be caused by the short period of follow up and the dropout of participants. The feasibility and the usefulness of the programme within the OHS setting were rated good by the participants. This programme to decrease WBV exposure was partially effective. Significant effects on intermediate objectives were observed. More research on the effectiveness of intervention in the field of WBV is needed.

  13. The impact of new technologies on shipboard command and control


    Oats, Trey D.; Erickson, Matthew C.


    Approved for public release, distribution is unlimited An investigation of how fuel cells, an integrated power system, and directed energy weapons will affect the shipboard command and control process. The focus is on the implementation of the new technologies onboard near-term and far-term destroyer variants and the resulting changes to the command and control process. Ensign, United States Naval Reserve

  14. Distributed automatic control of technological processes in conditions of weightlessness (United States)

    Kukhtenko, A. I.; Merkulov, V. I.; Samoylenko, Y. I.; Ladikov-Royev, Y. P.


    Some problems associated with the automatic control of liquid metal and plasma systems under conditions of weightlessness are examined, with particular reference to the problem of stability of liquid equilibrium configurations. The theoretical fundamentals of automatic control of processes in electrically conducting continuous media are outlined, and means of using electromagnetic fields for simulating technological processes in a space environment are discussed.

  15. Pseudoscience in Instructional Technology: The Case of Learner Control Research. (United States)

    Reeves, Thomas C.

    Scientific research that is conducted without the structure of a supporting scientific paradigm should be labeled pseudoscience in that such research is deceptive or false science. It is argued that much of the research in educational technology is pseudoscience, with the focus on learner control research. Learner control is the design feature of…

  16. A Randomized Controlled Pilot Study to Investigate the Effect of Whole-Body Vibration on Lower-Extremity Fatigue. (United States)

    Ansari, Noureddin Nakhostin; Naghdi, Soofia; Karimi-Zarchi, Hadi; Fakhari, Zahra; Hasson, Scott


    Whole-body vibration (WBV) is a type of weight-bearing exercise used in the field of sport and rehabilitation. There is no study on the effects of WBV on muscle recovery after a fatiguing activity. To determine the effects of a single WBV session on lower-extremity fatigue. Randomized controlled pilot study. University Physiotherapy Clinic. A total of 13 healthy young men volunteered to participate in this study. Subjects were randomly assigned into the WBV group (n = 7, mean age: 21 y) or control group (CG; n = 6, mean age: 20 y). Subjects in the WBV group participated in a single-session WBV (30 Hz, amplitude 4 mm, 2 min) after lower-extremity fatigue. Peak force of quadriceps muscle, single leg hop test, and Y-test were measured before inducing muscle fatigue (T0), immediately after completing the fatigue protocol (T1), after WBV (T2), and 15 min following the application of WBV (T3). The same method was applied in the CG while the WBV machine was turned off. Repeated-measure ANOVA revealed no significant differences between groups in any of the outcomes. The findings indicated that WBV was not effective in the recovery of lower-extremity fatigue in healthy young men.

  17. Advances in control system technology for aerospace applications

    CERN Document Server


    This book is devoted to Control System Technology applied to aerospace and covers the four disciplines Cognitive Engineering, Computer Science, Operations Research, and Servo-Mechanisms. This edited book follows a workshop held at the Georgia Institute of Technology in June 2012, where the today's most important aerospace challenges, including aerospace autonomy, safety-critical embedded software engineering, and modern air transportation were discussed over the course of two days of intense interactions among leading aerospace engineers and scientists. Its content provide a snapshot of today's aerospace control research and its future, including Autonomy in space applications, Control in space applications, Autonomy in aeronautical applications, Air transportation, and Safety-critical software engineering.

  18. INL Control System Situational Awareness Technology Annual Report 2012

    Energy Technology Data Exchange (ETDEWEB)

    Gordon Rueff; Bryce Wheeler; Todd Vollmer; Tim McJunkin; Robert Erbes


    The overall goal of this project is to develop an interoperable set of tools to provide a comprehensive, consistent implementation of cyber security and overall situational awareness of control and sensor network implementations. The operation and interoperability of these tools will fill voids in current technological offerings and address issues that remain an impediment to the security of control systems. This report provides an FY 2012 update on the Sophia, Mesh Mapper, Intelligent Cyber Sensor, and Data Fusion projects with respect to the year-two tasks and annual reporting requirements of the INL Control System Situational Awareness Technology report (July 2010).

  19. Vibration Analysis and Control of Flexible Beam by Using Smart Damping Structures (United States)

    Chen, Q.; Levy, C.


    The temperature effects on frequency, loss factor and control of a flexible beam with a constrained viscoelastic layer and shape memory alloy layer (SMA) are discussed. It is shown that the temperature in the SMA (actuation) layer is very important in the determination of frequency and loss factor of such a structure. The effects of damping layer shear modulus and damping layer height as affected by the temperature are also discussed. As temperature plays such an important role, it is, therefore, imperative to evaluate temperature effects on the control of the system as well. Results with and without active control are discussed.

  20. Vibrational Diver (United States)

    Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef


    The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.