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Sample records for hydraulically actuated flexible

  1. Modeling and control of a hydraulically actuated flexible-prismatic link robot

    Energy Technology Data Exchange (ETDEWEB)

    Love, L.; Kress, R.; Jansen, J.

    1996-12-01

    Most of the research related to flexible link manipulators to date has focused on single link, fixed length, single plane of vibration test beds. In addition, actuation has been predominantly based upon electromagnetic motors. Ironically, these elements are rarely found in the existing industrial long reach systems. This manuscript describes a new hydraulically actuated, long reach manipulator with a flexible prismatic link at Oak Ridge National Laboratory (ORNL). Focus is directed towards both modeling and control of hydraulic actuators as well as flexible links that have variable natural frequencies.

  2. Variable stiffness actuator based on fluidic flexible matrix composites and piezoelectric-hydraulic pump

    Science.gov (United States)

    Kim, Gi-Woo; Li, Suyi; Wang, K. W.

    2010-04-01

    Recently, a new biological-inspired fluidic flexible matrix composite (in short, F2MC) concept has been developed for linear/torsional actuation and structural stiffness tailoring. Although the actuation and the variable stiffness features of the F2MC have been successfully demonstrated individually, their combined functions and full potentials were not yet manifested. In addition, the current hydraulic pressurization systems are bulky and heavy, limiting the potential of the F2MC actuator. To address these issues, we synthesize a new variable stiffness actuator concept that can provide both effective actuation and tunable stiffness (dual-mode), incorporating the F2MC with a compact piezoelectric-hydraulic pump (in short, PHP). This dual-mode mechanism will significantly enhance the potential of the F2MC adaptive structures.

  3. Thermally Actuated Hydraulic Pumps

    Science.gov (United States)

    Jones, Jack; Ross, Ronald; Chao, Yi

    2008-01-01

    Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

  4. Smart Tendon Actuated Flexible Actuator

    Directory of Open Access Journals (Sweden)

    Md. Masum Billah

    2015-01-01

    Full Text Available We investigate the kinematic feasibility of a tendon-based flexible parallel platform actuator. Much of the research on tendon-driven Stewart platforms is devoted either to the completely restrained positioning mechanism (CRPM or to one particular type of the incompletely restrained positioning mechanism (IRPM where the external force is provided by the gravitational pull on the platform such as in cable-suspended Stewart platforms. An IRPM-based platform is proposed which uses the external force provided by a compliant member. The compliant central column allows the configuration to achieve n DOFs with n tendons. In particular, this investigation focuses on the angular deflection of the upper platform with respect to the lower platform. The application here is aimed at developing a linkable module that can be connected to one another so as to form a “snake robot” of sorts. Since locomotion takes precedence over positioning in this application, a 3-DOF Stewart platform is adopted. For an arbitrary angular displace of the end-effector, the corresponding length of each tendon can be determined through inverse kinematics. Mathematical singularities are investigated using the traditional analytical method of defining the Jacobian.

  5. Hydraulic involute cam actuator

    Science.gov (United States)

    Love, Lonnie J.; Lind, Randall F.

    2011-11-01

    Mechanical joints are provided in which the angle between a first coupled member and a second coupled member may be varied by mechanical actuators. In some embodiments the angle may be varied around a pivot axis in one plane and in some embodiments the angle may be varied around two pivot axes in two orthogonal planes. The joints typically utilize a cam assembly having two lobes with an involute surface. Actuators are configured to push against the lobes to vary the rotation angle between the first and second coupled member.

  6. Transputer Control of Hydraulic Actuators and Robots

    DEFF Research Database (Denmark)

    Conrad, Finn

    1996-01-01

    Results from a Danish mechatronics research program entitled IMCIA - Intelligent Control and Intelligent Actuators. The objective is development of intelligent actuators for intelligent motion control. A mechatronics test facility with a transputer controlled hydraulic robot suiteable for real...

  7. Transputer Control of Hydraulic Actuators and Robots

    DEFF Research Database (Denmark)

    Conrad, Finn

    1996-01-01

    Results from a Danish mechatronics research program entitled IMCIA - Intelligent Control and Intelligent Actuators. The objective is development of intelligent actuators for intelligent motion control. A mechatronics test facility with a transputer controlled hydraulic robot suiteable for real...

  8. Hydraulic Actuator for Ganged Control Rods

    Science.gov (United States)

    Thompson, D. C.; Robey, R. M.

    1986-01-01

    Hydraulic actuator moves several nuclear-reactor control rods in unison. Electromagnetic pump pushes liquid lithium against ends of control rods, forcing them out of or into nuclear reactor. Color arrows show lithium flow for reactor startup and operation. Flow reversed for shutdown. Conceived for use aboard spacecraft, actuator principle applied to terrestrial hydraulic machinery involving motion of ganged rods.

  9. Singular perturbation approach for control of hydraulically driven flexible manipulator

    Institute of Scientific and Technical Information of China (English)

    LI Guang; WU Min

    2005-01-01

    The hydraulic flexible manipulator system is divided into two parts: flexible arm dynamics and hydraulic servomechanism, a driving Jacobian is derived to connect these two parts. Taking hydraulic actuator force as virtual input, a singular perturbed composite model is formulated and used to design composite controllers for the flexible link, in which the slow subsystem controller dominates the trajectory tracking, and then a fast controller is designed to damp out the vibration of the flexible structure. Moreover, the backstepping technique is applied to regulate the spool position of a hydraulic valve to provide the required force. Simulation results are provided to show the effectiveness of the presented approach.

  10. Hydraulic Actuators with Autonomous Hydraulic Supply for the Mainline Aircrafts

    Directory of Open Access Journals (Sweden)

    I. S. Shumilov

    2014-01-01

    Full Text Available Applied in the aircraft control systems, hydraulic servo actuators with autonomous hydraulic supply, so-called, hydraulic actuators of integrated configuration, i.e. combination of a source of hydraulic power and its load in the single unit, are aimed at increasing control system reliability both owing to elimination of the pipelines connecting the actuator to the hydraulic supply source, and owing to avoidance of influence of other loads failure on the actuator operability. Their purpose is also to raise control system survivability by eliminating the long pipeline communications and their replacing for the electro-conductive power supply system, thus reducing the vulnerability of systems. The main reason for a delayed application of the hydraulic actuators in the cutting-edge aircrafts was that such aircrafts require hydraulic actuators of considerably higher power with considerable heat releases, which caused an unacceptable overheat of the hydraulic actuators. Positive and negative sides of the hydraulic actuators, their alternative options of increased reliability and survivability, local hydraulic systems as an advanced alternative to independent hydraulic actuators are considered.Now to use hydraulic actuators in mainline aircrafts is inexpedient since there are the unfairly large number of the problems reducing, first and last, safety of flights, with no essential weight and operational advantages. Still works to create competitive hydraulic actuators ought to be continued.Application of local hydraulic systems (LHS will allow us to reduce length of pressure head and drain pipelines and mass of pipelines, as well as to raise their general fail-safety and survivability. Application of the LHS principle will allow us to use a majority of steering drive advantages. It is necessary to allocate especially the following:- ease of meeting requirements for the non-local spread of the engine weight;- essentially reducing length and weight of

  11. 14 CFR 33.72 - Hydraulic actuating systems.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic actuating systems. 33.72 Section... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.72 Hydraulic actuating systems. Each hydraulic actuating system must function properly under all conditions in which...

  12. NEW HYDRAULIC ACTUATOR'S POSITION SERVOCONTROL STRATEGY

    Institute of Scientific and Technical Information of China (English)

    KE Zunrong; ZHU Yuquan; LING Xuan

    2007-01-01

    A new hydraulic actuator-hydraulic muscle (HM) is described, and the actuator's features and applications are analyzed, then a position servocontrol system in which HM is main actuator is set up. The mathematical model of the system is built up and several control strategies are discussed. Based on the mathematical model, simulation research and experimental investigation with subsection PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control adopted respectively are carried out, and the results indicate that compared with PID control, neural network self-adaptive PID control and single neuron self-adaptive PID control don't need controlled system's accurate model and have fast response, high control accuracy and strong robustness, they are very suitable for HM position servo control system.

  13. Analysis of Innovative Design of Energy Efficient Hydraulic Actuators

    OpenAIRE

    M Osman Abdalla

    2013-01-01

    Hydraulic cylinder actuators are used extensively in industrial, construction and agricultural works. The small sized outlet ports of the cylinders resist the flow of discharged oil; and as a result the piston motion is slowed down. This causes a lot of heat generation and energy loss within the actuators. The study investigates and analyzes the possibilities of reducing the hydraulic resistance and increasing efficiency of the hydraulic actuator. Conventional hydraulic cylinders are simulate...

  14. Control arrangement for the actuation of hydraulic consumers

    Energy Technology Data Exchange (ETDEWEB)

    Kussel, W.; Dettmers, M.; Weirich, W.

    1988-11-09

    An arrangement for controlling the actuation of hydraulic consumers, by selectively connecting the consumers to hydraulic pressure and return lines; the control arrangement comprising a respective hydraulically operated directional control valve associated with each of the hydraulic consumers, a respective electro-magnetically operated pre-control valve associated with each of the hydraulic directional control valves, and further electro-magnetically operated directional control valve means associated with the pre-control valves, each of the hydraulic consumers being connectible to the hydraulic pressure or return lines via the associated hydraulically operated directional control valve which is actuatable by a hydraulic control line leading from the output of the associated pre-control valve, wherein the inputs of the pre-control valves are connected directly to the hydraulic return line and indirectly, via the further control valve means, to the hydraulic return line or to a hydraulic control pressure line.

  15. Analysis of Innovative Design of Energy Efficient Hydraulic Actuators

    Directory of Open Access Journals (Sweden)

    M Osman Abdalla

    2013-01-01

    Full Text Available Hydraulic cylinder actuators are used extensively in industrial, construction and agricultural works. The small sized outlet ports of the cylinders resist the flow of discharged oil; and as a result the piston motion is slowed down. This causes a lot of heat generation and energy loss within the actuators. The study investigates and analyzes the possibilities of reducing the hydraulic resistance and increasing efficiency of the hydraulic actuator. Conventional hydraulic cylinders are simulated in FLUENT. Results show that the small outlet ports are the sources of energy loss in hydraulic cylinders. A new hydraulic system was proposed as a solution to relieve the hydraulic resistance in the actuators. The proposed system is a four ports hydraulic cylinder fitted with a novel flow control valve. The proposed four ports cylinder was simulated and parameters such as ports sizes, loads and pressures are varied during the simulation. The hydraulic resisting forces, piston speed and mass flow rates are computed. Results show that the hydraulic resistance is significantly reduced in the proposed four ports actuators; and the proposed cylinders run faster than the conventional cylinders and a considerable amount of energyis saved as well.

  16. Electrorheological fluid-actuated flexible platform

    Science.gov (United States)

    Liu, Liyu; Niu, Xize; Wen, Weijia; Sheng, Ping

    2006-04-01

    The design, fabrication, and performance of an electrorheological (ER) fluid-actuated flexible platform integrated on a microfluidic chip are reported in this letter. The digitally regulated ER microvalves control the four diaphragms on which a platform is sustained. With electrical input signals, the platform can perform vibrations at tunable frequencies as well as generate complex leveling modes. The flexible platform can potentially act as a microdamper when its inputs are generated from a sensor, in combination with a feedback control system.

  17. Feasibility of transparent flexible ultrasonic haptic actuator

    Science.gov (United States)

    Akther, Asma; Kafy, Abdullahil; Kim, Hyun Chan; Kim, Jaehwan

    2016-04-01

    Ultrasonic haptics actuator is a device that can create a haptic feedback to user's hand. The modulation of ultrasonic frequency can give different textures to the users. In this study, a feasibility of the ultrasonic haptic actuator made on a flexible piezoelectric substrate is investigated. As the piezoelectric substrate helps to propagate flexural waves, a pair of interdigital transducer (IDT) with reflectors can produce standing waves, which can increase the vibrational displacement of the actuator. A pair of IDT pattern was fabricated on a piezoelectric polymer substrate. A finite element analysis is at first performed to design the actuator. A sinusoidal excitation voltage is applied on IDT electrodes at ultrasonic frequencies and the displacement waveforms are found. The displacement waveforms clearly represent how ultrasonic waves propagate through the piezoelectric substrate.

  18. FLEXIBLE STRUCTURE WITH INTEGRATED SENSOR/ACTUATOR

    DEFF Research Database (Denmark)

    2003-01-01

    A polymer-based flexible structure with integrated sensing/actuator means is presented. Conventionally, silicon has been used as a piezo-resistive material due to its high gauge factor and thereby high sensitivity to strain changes in a sensor. By using the fact that e.g. an SU-8 based polymer...

  19. Adaptive Non-linear Control of Hydraulic Actuator Systems

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Conrad, Finn

    1998-01-01

    Presentation of two new developed adaptive non-liner controllers for hydraulic actuator systems to give stable operation and improved performance.Results from the IMCIA project supported by the Danish Technical Research Council (STVF).......Presentation of two new developed adaptive non-liner controllers for hydraulic actuator systems to give stable operation and improved performance.Results from the IMCIA project supported by the Danish Technical Research Council (STVF)....

  20. Servo-elastic dynamics of a hydraulic actuator pitching a blade with large deflections

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig; Kallesøe, Bjarne Skovmose

    2007-01-01

    This paper deals with the servo-elastic dynamics of a hydraulic pitch actuator acting on a largely bend wind turbine blade. The compressibility of the oil and flexibility of the hoses introduce a dynamic mode in the pitch bearing degree of freedom. This mode may obtain negative damping...... if the proportional gain on the actuator position error is defined too large relative to the viscous forces in the hydraulic system and the total rotational inertia of the pitch bearing degree of freedom. A simple expression for the stability limit of this proportional gain is derived for tuning the gain based...

  1. Hydraulic vs. Electric: A Review of Actuation Systems in Offshore Drilling Equipment

    Directory of Open Access Journals (Sweden)

    Witold Pawlus

    2016-01-01

    Full Text Available This article presents a survey on actuation systems encountered in offshore drilling applications. Specifically, it focuses on giving a comparison of hydraulic and electric drivetrains along with detailed explanations of their advantages and drawbacks. A significant number of industrial case studies is examined in addition to the collection of academic publications, in order to accurately describe the current market situation. Some key directions of research and development required to satisfy increasing demands on powertrains operating offshore are identified. The impact of the literature and application surveys is further strengthened by benchmarking two designs of a full-scale pipe handling machine. Apart from other benefits, the electrically actuated machine reduces the total power consumption by 70% compared to its hydraulically driven counterpart. It is concluded that electric actuation systems, among other advantages, in general offer higher efficiency and flexibility, however, in some specific applications (such as energy accumulation or translational motion control hydraulic powertrains are favorable.

  2. Design of Transputer Controllers for Hydraulic Actuator Systems

    DEFF Research Database (Denmark)

    Conrad, Finn

    1996-01-01

    The paper deals with how transputers can be applied for fast controllers for hydraulic actuator systems. A general transputer-based control systems including a data acquisition transputer subsystem is presented. An application case: development of a mechatronic test facility with a fast hydraulic...

  3. Climbing robot actuated by meso-hydraulic artificial muscles

    Science.gov (United States)

    Bryant, Matthew; Fitzgerald, Jason; Miller, Samuel; Saltzman, Jonah; Kim, Sangkyu; Lin, Yong; Garcia, Ephrahim

    2014-03-01

    This paper presents the design, construction, experimental characterization, and system testing of a legged, wall-climbing robot actuated by meso-scale hydraulic artificial muscles. While small wall-climbing robots have seen increased research attention in recent years, most authors have primarily focused on designs for the gripping and adhesion of the robot to the wall, while using only standard DC servo-motors for actuation. This project seeks to explore and demonstrate a different actuation mechanism that utilizes hydraulic artificial muscles. A four-limb climbing robot platform that includes a full closed-loop hydraulic power and control system, custom hydraulic artificial muscles for actuation, an on-board microcontroller and RF receiver for control, and compliant claws with integrated sensing for gripping a variety of wall surfaces has been constructed and is currently being tested to investigate this actuation method. On-board power consumption data-logging during climbing operation, analysis of the robot kinematics and climbing behavior, and artificial muscle force-displacement characterization are presented to investigate and this actuation method.

  4. Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves

    OpenAIRE

    HUANG, Ye; Liu, Changsheng; Shiongur Bamed

    2014-01-01

    Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under...

  5. Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves

    Directory of Open Access Journals (Sweden)

    Ye HUANG

    2014-09-01

    Full Text Available Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under light loads and wearing of the variable-displacement pump. To overcome these shortcomings, this article designs a closed hydraulic control system in which an AC servo motor drives a quantitative pump that controls a spiral swinging hydraulic cylinder, and analyzes and calculates the structure and parameters of a spiral swinging hydraulic cylinder. The hydraulic system adjusts the servo motor’s speed according to the requirements of the control system, and the motor power matches the power provided to components, thus eliminating the throttling loss of hydraulic circuits. The system is compact, produces a large output force, provides stable transmission, has a quick response, and is suitable as a hydraulic control system of a large butterfly valve.

  6. Nonlinear Model-Based Fault Detection for a Hydraulic Actuator

    NARCIS (Netherlands)

    Van Eykeren, L.; Chu, Q.P.

    2011-01-01

    This paper presents a model-based fault detection algorithm for a specific fault scenario of the ADDSAFE project. The fault considered is the disconnection of a control surface from its hydraulic actuator. Detecting this type of fault as fast as possible helps to operate an aircraft more cost effect

  7. Towards Autonomous Control of Hydraulic Actuator Systems

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Conrad, Finn

    1998-01-01

    Presentation of new developed control algorithms to increase autonomy and intelligence of hydraulic control systems. A refinement of relaytuning method is used to determine the control parameters of a lag/lead controller and a poleplacement controller. Further, a fail-safe function is developed t...

  8. Power management in hydraulically actuated mobile equipment

    DEFF Research Database (Denmark)

    Pedersen, Henrik Clemmensen; Andersen, Torben Ole; Hansen, Michael Rygaard

    2008-01-01

    The focus of the current paper is on the control of hydraulic systems when utilizing the advances that electronic control may bring with regard to power management, prioritized flow sharing and anti-stall, arising from being able to control both pump, valves and engine electronically. A simple mo...

  9. Simulation and control of an electro-hydraulic actuated clutch

    Science.gov (United States)

    Balau, Andreea-Elena; Caruntu, Constantin-Florin; Lazar, Corneliu

    2011-08-01

    The basic function of any type of automotive transmission is to transfer the engine torque to the vehicle with the desired ratio smoothly and efficiently and the most common control devices inside the transmission are clutches and hydraulic pistons. The automatic control of the clutch engagement plays a crucial role in Automatic Manual Transmission (AMT) vehicles, being seen as an increasingly important enabling technology for the automotive industry. It has a major role in automatic gear shifting and traction control for improved safety, drivability and comfort and, at the same time, for fuel economy. In this paper, a model for a wet clutch actuated by an electro-hydraulic valve used by Volkswagen for automatic transmissions is presented. Starting from the developed model, a simulator was implemented in Matlab/Simulink and the model was validated against data obtained from a test-bench provided by Continental Automotive Romania, which includes the Volkswagen wet clutch actuated by the electro-hydraulic valve. Then, a predictive control strategy is applied to the model of the electro-hydraulic actuated clutch with the aims of controlling the clutch piston displacement and decreasing the influence of the network-induced delays on the control performances. The simulation results obtained with the proposed method are compared with the ones obtained with different networked controllers and it is shown that the strategy proposed in this paper can indeed improve the performances of the control system.

  10. Flexible dielectric elastomer actuators for wearable human-machine interfaces

    Science.gov (United States)

    Bolzmacher, Christian; Biggs, James; Srinivasan, Mandayam

    2006-03-01

    Wearable dielectric elastomer actuators have the potential to enable new technologies, such as tactile feedback gloves for virtual reality, and to improve existing devices, such as automatic blood pressure cuffs. They are potentially lighter, quieter, thinner, simpler, and cheaper than pneumatic and hydraulic systems now used to make compliant, actuated interfaces with the human body. Achieving good performance without using a rigid frame to prestrain the actuator is a fundamental challenge in using these actuators on body. To answer this challenge, a new type of fiber-prestrained composite actuator was developed. Equations that facilitate design of the actuator are presented, along with FE analysis, material tests, and experimental results from prototypes. Bending stiffness of the actuator material was found to be comparable to textiles used in clothing, confirming wearability. Two roll-to-roll machines are also presented that permit manufacture of this material in bulk as a modular, compact, prestressed composite that can be cut, stacked, and staggered, in order to build up actuators for a range of desired forces and displacements. The electromechanical properties of single- layered actuators manufactured by this method were measured (N=5). At non-damaging voltages, blocking force ranged from 3,7-5,0 gram per centimeter of actuator width, with linear strains of 20,0-30%. Driving the actuators to breakdown produced maximum force of 8,3-10 gram/cm, and actuation strain in excess 30%. Using this actuator, a prototype tactile display was constructed and demonstrated.

  11. Pneumatic squirming robot based on flexible pneumatic actuator

    Science.gov (United States)

    Yang, Qinghua; Zhang, Libin; Bao, Guanjun; Ruan, Jian

    2005-12-01

    The design of a kind of pneumatic squirming robot is presented. It is based on the use of flexible pneumatic actuator. The flexible pneumatic actuator was made of caoutchouc. Its working principle is described. The structure, working principle, pneumatic and electrical control system of the pneumatic squirming robot are designed. All of the actuator's driving and squirming parts are composed of pneumatic elements. The vacuum osculums, which act as feet, are connected to the flexible pneumatic actuator. When the vacuum pumps operate, vacuum will be produced in the corresponding osculums, which can adsorb on the contacting surface and orient the robot. The actuator, operating under air pressure, drives the robot. By controlling the vacuum pumps and the actuator, straight and bending squirming of this robot can be obtained.

  12. Disturbance observer based position tracking of electro-hydraulic actuator

    Institute of Scientific and Technical Information of China (English)

    国凯; 魏建华; 田启岩

    2015-01-01

    A nonlinear controller based on an extended second-order disturbance observer is presented to track desired position for an electro-hydraulic single-rod actuator in the presence of both external disturbances and parameter uncertainties. The proposed extended second-order disturbance observer deals with not only the external perturbations, but also parameter uncertainties which are commonly regarded as lumped disturbances in previous researches. Besides, the outer position tracking loop is designed with cylinder load pressure as output; and the inner pressure control loop provides the hydraulic actuator the characteristic of a force generator. The stability of the closed-loop system is provided based on Lyapunov theory. The performance of the controller is verified through simulations and experiments. The results demonstrate that the proposed nonlinear position tracking controller, together with the extended second-order disturbance observer, gives an excellent tracking performance in the presence of parameter uncertainties and external disturbance.

  13. PRINCIPLE OF POST-PRODUCTION DESIGN OF HYDRAULIC ACTUATORS

    Directory of Open Access Journals (Sweden)

    A. V. Puzanov

    2015-01-01

    Full Text Available In work the problem of design-technology preparation of production of hydraulic actuators is staticized. The structure and business processes of design and production are analysed. Methods and means of reorganization of project works for the purpose of cutting-down of time of preparation of production are offered. The directions of reorganization of process of design are formulated. The principle of carrying out procedures of design-technology preparation of production of hydraulic actuators with use of ready elements of a production cycle is considered. The scheme of their practical realization at machine-building enterprise is offered. The assessment of growth of efficiency of design-technology preparation of production is given in machine-building enterprise.

  14. A New Type of Hydraulic Actuator Using Electrorheological Fluids

    Science.gov (United States)

    Wendt, Eckhard; Büsing, Klaus W.

    Electrorheological Fluids (ERF) are usually used in semi active damping elements, e.g. shock absorbers or engine mounts because of their continuously controllable shear stress. A totally new field of application may be achieved, if an ERF is used as a hydraulic fluid and not only as a control medium. In this case a fundamental need is the capability to produce a volume flow by using normal hydraulic pumps, e.g. gear pumps. The ERF and the hydraulic components both must have a long lifetime without unusual wear. Bayer AG has developed an ERF based on soft crosslinked PU-particles dispersed in silicone oil. These ERF are characterised by a low basic viscosity, a high ER-effect and a moderate conductivity. Compared with previous ERF where hard inorganic particles were used, the new fluid is not abrasive. It is foremostly this characteristic which gives the possibility of using the ERF in hydraulic systems with high shear rates and high shear stresses. The usage of ERF as hydraulic fluid allows the construction of proportional valves without mechanically driven parts. The control of the pressure drop over the valves is realised directly by an electrical signal. It is possible to realise actuators with very fast response times since the reaction time of ERF is within milliseconds. For demonstration purpose Bayer AG has built an actuator which is controlled by an electrorheological valve-block. The calculation of the dimension of this actuator and the valves will be shown and the realised response time will be demonstrated.

  15. Investigation and Development of the Thermal Preparation System of the Trailbuilder Machinery Hydraulic Actuator

    Science.gov (United States)

    Konev, V.; Polovnikov, E.; Krut, O.; Merdanov, Sh; Zakirzakov, G.

    2017-07-01

    It’s determined that the main part of trailbuilders operated in the North is the technology equipped by the hydraulic actuator. Further development of the northern territories will demand using of various means and ways machinery thermal preparation, and also the machinery of the northern fulfillment. On this basis problems in equipment operation are defined. One of the main is efficiency supplying of a hydraulic actuator. On the basis of the operating conditions’ analysis of trailbuilder hydraulic actuator operation it is determined, that under low negative temperatures the means of thermal preparation are necessary. The existing systems warm up only a hydraulic tank or warming up of the hydro equipment before the machinery operation is carried out under loading with intensive wears. Thus, with the purpose to raise the efficiency of thermal hydraulic actuator, operated far from stationary bases autonomous, energy saving, not expensive in creation and operation systems are necessary. In accordance with the analysis of means and ways of the thermal preparation of the hydraulic actuator and the thermal balance calculations of the (internal) combustion engine the system of the hydraulic actuator heating is offered and is being investigated. It contains a local hydraulic actuator warming up and the system of internal combustion engine heat utilization. Within research operation conditions of the local hydraulic actuator heating are viewed and determined, taking into account constructive changes to the local hydraulic actuator heating. Mathematical modelling of the heat technical process in the modernized hydraulic actuator is considered. As a result temperature changes of the heat-transfer and the hydraulic cylinder in time are determined. To check the theoretical researches and to define dependences on hydraulic actuator warming up, the experimental installation is made. It contains the measuring equipment, a small tank with the heat exchanger of the burnt gases

  16. Design of a hydraulic actuator for active control of rotating machinery

    Science.gov (United States)

    Rashidi, Majid; Dirusso, Eliseo

    1991-01-01

    A hydraulic actuator is described which consists of a pump, a hydraulic servo-valve, and a thin elastic plate which transduces the generated pressure variations into forces acting on a mass which simulates the bearing of a rotor system. An actuator characteristic number is defined to provide a base for an optimum design of force actuators with combined weight, frequency, and force considerations. This characteristic number may also be used to compare hydraulic and electromagnetic force actuators. In tests, this actuator generated 182.3 Newton force at a frequency of 100 Hz and a displacement amplitude of 5.8 x 10 exp -5 meter.

  17. Development of hydraulic brake actuator for active brake control; Active brake seigyoyo yuatsu booster no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Konishi, Y.; Hattori, M. Sugisawa, M.; Nishii, M. [Aisin Seiki Co. Ltd., Aichi (Japan)

    1997-10-01

    Recently, application of active brake control systems of the vehicle are increasing. (Vehicle stability control, Panic brake assist ) We have developed a new hydraulic brake actuator for active brake control systems. New hydraulic brake actuator is composed of the three parts. (Hydraulic booster unit, Power supply unit, Control valve unit) This report describes the construction of the new hydraulic booster unit. 2 refs., 10 figs.

  18. Hydraulic engine valve actuation system including independent feedback control

    Science.gov (United States)

    Marriott, Craig D

    2013-06-04

    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

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

    Directory of Open Access Journals (Sweden)

    J. Fei

    2008-03-01

    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.

  20. Multiplexed hydraulic valve actuation using ionic liquid filled soft channels and Braille displays

    Science.gov (United States)

    Gu, Wei; Chen, Hao; Tung, Yi-Chung; Meiners, Jens-Christian; Takayama, Shuichi

    2007-01-01

    Pneumatic actuation with multilayer soft lithography enables operation of up to thousands of valves in parallel using far fewer control lines. However, it is dependent on macroscopic switches and external pressure sources that require interconnects and limit portability. The authors present a more portable and multiplexed valve actuation strategy that uses a grid of mechanically actuated Braille pins to hydraulically, rather than pneumatically, deform elastic actuation channels that act as valves. Experimental and theoretical analyses show that the key to reliable operation of the hydraulic system is the use of nonvolatile ionic liquids as the hydraulic fluid.

  1. Asymmetric Bellow Flexible Pneumatic Actuator for Miniature Robotic Soft Gripper

    Directory of Open Access Journals (Sweden)

    Ganesha Udupa

    2014-01-01

    Full Text Available The necessity of the soft gripping devices is increasing day-by-day in medical robotics especially when safe, gentle motions and soft touch are necessary. In this paper, a novel asymmetric bellow flexible pneumatic actuator (AFPA has been designed and fabricated to construct a miniaturised soft gripper that could be used to grip small objects. The model of AFPA is designed using solid works and its bending motion is simulated in Abaqus software for optimisation and compared with experimental results. The actuator is fabricated using compression molding process that includes micromachining of the molds. Experiments conducted show the bending characteristics of the actuator at different pressures. The actuator shows excellent bending performance and the eccentricity in its design supports increased bending or curling motion up to a certain extent compared to normal bellows without eccentricity. The effects of profile shape and eccentricity on the actuator performance are analysed and the results are presented.

  2. Vibration control of a flexible structure with electromagnetic actuators

    DEFF Research Database (Denmark)

    Gruzman, Maurício; Santos, Ilmar

    2016-01-01

    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....

  3. Parametric identification of a servo-hydraulic actuator for real-time hybrid simulation

    Science.gov (United States)

    Qian, Yili; Ou, Ge; Maghareh, Amin; Dyke, Shirley J.

    2014-10-01

    In a typical Real-time Hybrid Simulation (RTHS) setup, servo-hydraulic actuators serve as interfaces between the computational and physical substructures. Time delay introduced by actuator dynamics and complex interaction between the actuators and the specimen has detrimental effects on the stability and accuracy of RTHS. Therefore, a good understanding of servo-hydraulic actuator dynamics is a prerequisite for controller design and computational simulation of RTHS. This paper presents an easy-to-use parametric identification procedure for RTHS users to obtain re-useable actuator parameters for a range of payloads. The critical parameters in a linearized servo-hydraulic actuator model are optimally obtained from genetic algorithms (GA) based on experimental data collected from various specimen mass/stiffness combinations loaded to the target actuator. The actuator parameters demonstrate convincing convergence trend in GA. A key feature of this parametric modeling procedure is its re-usability under different testing scenarios, including different specimen mechanical properties and actuator inner-loop control gains. The models match well with experimental results. The benefit of the proposed parametric identification procedure has been demonstrated by (1) designing an H∞ controller with the identified system parameters that significantly improves RTHS performance; and (2) establishing an analysis and computational simulation of a servo-hydraulic system that help researchers interpret system instability and improve design of experiments.

  4. Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems

    Directory of Open Access Journals (Sweden)

    Xavier Arouette

    2010-03-01

    Full Text Available We have developed a hydraulic displacement amplification mechanism (HDAM and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS membranes. The geometry with input and output surfaces having different cross-sectional areas creates amplification. By combining the HDAM with micro-actuators, we can amplify the input displacement generated by the actuators, which is useful for applications requiring large deformation, such as tactile displays. We achieved a mechanism offering up to 18-fold displacement amplification for static actuation and 12-fold for 55 Hz dynamic actuation.

  5. Chapter 2. Mode-switching in Hydraulic Actuator Systems - An Experiment

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Conrad, Finn; Ravn, Anders P.;

    1996-01-01

    Experiments with mode-switching adaptive control of actuators to drive a hydraulic test robot.The research is a cooperation with IT, DTU within the IMCIA Research Programme supported by the Danish Technical Research Council, STVF.......Experiments with mode-switching adaptive control of actuators to drive a hydraulic test robot.The research is a cooperation with IT, DTU within the IMCIA Research Programme supported by the Danish Technical Research Council, STVF....

  6. Knowledge-based Adaptive Tracking Control of Electro-hydraulic Actuator Systems

    DEFF Research Database (Denmark)

    Hansen, Poul Erik

    1997-01-01

    The paper deal with intelligent motion control and electro-hydraulic actuator systems for multiaxis machynes and robots.The research results are from the IMCIA research Programme supported by the Danish Technical Research Council, STVF.......The paper deal with intelligent motion control and electro-hydraulic actuator systems for multiaxis machynes and robots.The research results are from the IMCIA research Programme supported by the Danish Technical Research Council, STVF....

  7. Understanding the Space Shuttle Main Engine Hydraulic Actuation System and Reviewing Its Evolution

    Science.gov (United States)

    McWade, Robert J.; Minor, Robert B.; McNutt, Leslie M.

    2010-01-01

    The complex engine start and thrust control requirements of the Space Shuttle Main Engine (SSME) require unique valve, actuator and control system hardware. The Hydraulic Actuation System (HAS) was designed, developed, and now operates to meet tight engine control requirement limits to assure safe, reliable and correct engine thrust at all times. The actuator is designed to be fail safe and fail operate in the areas where redundancy is important. The HAS has an additional pneumatic operating capability that insures a safe sequential closure of all actuators and propellant valves in the event of the loss of hydraulic system pressure or loss of electrical closed loop control of the actuator. The objective of this paper is to provide a complete description of the actuator s internal operating system, along with its interaction with all SSME system interfaces. Additionally the paper addresses the challenges, problems identified, and corrected, and lessons learned, during the course of the almost 35 years of engine operation.

  8. Understanding the Space Shuttle Main Engine Hydraulic Actuation System and Reviewing Its Evolution

    Science.gov (United States)

    McWade, Robert J.; Minor, Robert B.; McNutt, Leslie M.

    2010-01-01

    The complex engine start and thrust control requirements of the Space Shuttle Main Engine (SSME) require unique valve, actuator and control system hardware. The Hydraulic Actuation System (HAS) was designed, developed, and now operates to meet tight engine control requirement limits to assure safe, reliable and correct engine thrust at all times. The actuator is designed to be fail safe and fail operate in the areas where redundancy is important. The HAS has an additional pneumatic operating capability that insures a safe sequential closure of all actuators and propellant valves in the event of the loss of hydraulic system pressure or loss of electrical closed loop control of the actuator. The objective of this paper is to provide a complete description of the actuator s internal operating system, along with its interaction with all SSME system interfaces. Additionally the paper addresses the challenges, problems identified, and corrected, and lessons learned, during the course of the almost 35 years of engine operation.

  9. A Simple and Robust Sliding Mode Velocity Observer for Moving Coil Actuators in Digital Hydraulic Valves

    DEFF Research Database (Denmark)

    Nørgård, Christian; Schmidt, Lasse; Bech, Michael Møller

    2016-01-01

    This paper focuses on estimating the velocity and position of fast switching digital hydraulic valves actuated by electromagnetic moving coil actuators, based on measurements of the coil current and voltage. The velocity is estimated by a simple first-order sliding mode observer architecture and ...

  10. Hydraulically controlled flexible arm can bend in any direction

    Science.gov (United States)

    Griffin, F. D.

    1966-01-01

    Arm assembly consisting of four flexible tubes controlled by a four-way hydraulic or pneumatic valve can bend in any direction. The flexible arm could be used for probing areas that cannot be reached by ordinary tools, handling hazardous materials, and for graph recording.

  11. Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

    Science.gov (United States)

    Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.

  12. Flexible Robotic Spine Actuated by Shape Memory Alloy

    OpenAIRE

    2014-01-01

    A flexible robotic spine actuated by shape memory alloy (SMA) can achieve both bending motion and impact absorption, which will allow robots to realize a variety of postures. In this paper, the robotic spine is designed and simplified into a multi-segment dynamic model based on several verified assumptions. The SMA wire is modelled using the Seelecke-Muller-Acenbach theory. An iterative algorithm is developed to address the external forces distributed along the spine and compute the spine’s b...

  13. Flexible Circuits and Soft Actuators by Printing Assembly of Graphene.

    Science.gov (United States)

    Li, Wenbo; Li, Fengyu; Li, Huizeng; Su, Meng; Gao, Meng; Li, Yanan; Su, Dan; Zhang, Xingye; Song, Yanlin

    2016-05-18

    An effective way to improve the electrical conductivity of printed graphene patterns was demonstrated by realizing the assembly of giant graphene oxide sheets during the printing process. The synergetic effect of printing-induced orientation and evaporation-induced interfacial assembly facilitated the formation of laminar-structured patterns. The resulting patterns after chemical reduction showed excellent electrical conductivity in printed graphene electronics. Because of their high conductivity, mechanical flexibility, and advantage in pattern design, printed graphene electrodes were applied in electrical-driven soft actuators, which can realize controllable deformation with low driving voltage. Such achievements will be of great significance for the development of graphene-based flexible and printed electronics.

  14. Smart Material-actuated Flexible Tendon-based Snake Robot

    Directory of Open Access Journals (Sweden)

    Mohiuddin Ahmed

    2016-05-01

    Full Text Available A flexible snake robot has better navigation ability compare with the existing electrical motor-based rigid snake robot, due to its excellent bending capability during navigation inside a narrow maze. This paper discusses the modelling, simulation and experiment of a flexible snake robot. The modelling consists of the kinematic analysis and the dynamic analysis of the snake robot. A platform based on the Incompletely Restrained Positioning Mechanism (IRPM is proposed, which uses the external force provided by a compliant flexible beam in each of the actuators. The compliant central column allows the configuration to achieve three degrees of freedom (3DOFs with three tendons. The proposed flexible snake robot has been built using smart material, such as electroactive polymers (EAPs, which can be activated by applying power to it. Finally, the physical prototype of the snake robot has been built. An experiment has been performed in order to justify the proposed model.

  15. Robust Control of a Hydraulically Actuated Manipulator Using Sliding Mode Control

    DEFF Research Database (Denmark)

    Hansen, Michael Rygaard; Andersen, Torben Ole; Pedersen, Henrik Clemmensen

    2005-01-01

    This paper presents an approach to robust control called sliding mode control (SMC) applied to the a hydraulic servo system (HSS), consisting of a servo valve controlled symmetrical cylinder. The motivation for applying sliding mode control to hydraulically actuated systems is its robustness towa...

  16. Development and Analysis of Flexible Thin Actuator with a Built-in Fluid Pressure Source

    Directory of Open Access Journals (Sweden)

    Senzaki Shinji

    2016-01-01

    Full Text Available A flexible thin actuator using gas-liquid phase-change of a low boiling point liquid that can generate large force was proposed and tested in the previous study. The tested actuator is an envelope-type actuator that is made of laminating plastic sheets, low boiling point liquid and a flexible heater. In this paper, the analytical model of the flexible thin actuator was proposed and tested. The system parameters of the actuator were also identified. As a result, it was confirmed that the proposed analytical model can predict the behaviour of the tested actuator.

  17. Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

    Science.gov (United States)

    Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

    2017-01-01

    Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water. PMID:28145412

  18. Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water

    Science.gov (United States)

    Yuk, Hyunwoo; Lin, Shaoting; Ma, Chu; Takaffoli, Mahdi; Fang, Nicolas X.; Zhao, Xuanhe

    2017-02-01

    Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.

  19. Modelling of Moving Coil Actuators in Fast Switching Valves Suitable for Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller

    2015-01-01

    The efficiency of digital hydraulic machines is strongly dependent on the valve switching time. Recently, fast switching have been achieved by using a direct electromagnetic moving coil actuator as the force producing element in fast switching hydraulic valves suitable for digital hydraulic...... machines. Mathematical models of the valve switching, targeted for design optimisation of the moving coil actuator, are developed. A detailed analytical model is derived and presented and its accuracy is evaluated against transient electromagnetic finite element simulations. The model includes...... an estimation of the eddy currents generated in the actuator yoke upon current rise, as they may have significant influence on the coil current response. The analytical model facilitates fast simulation of the transient actuator response opposed to the transient electro-magnetic finite element model which...

  20. Flexible electrode and its characteristics for micro actuator

    Science.gov (United States)

    Jung, Youngdae; Jeong, Haedo; Jeong, Eunsoo; Park, Hansu; Jo, Namju

    2002-11-01

    Flexible electrode is essential for longitudinal or traverse type of micro-actuator using electrostrictive(ES) polymer. In this paper, two types of flexible electrode using conductive polymer(CP), carbon black composite and polypyrrole(PPy), was developed for a membrane type and unimorph type ES actuator using PU. At first, electrode using carbon black powder mixed with water-dispersed polyurethane was made and its displacement and dynamic characteristics were measured and compared with commercial conductive grease. Water-dispersed PU was produced by modified acetone process, using methylethylketone and acetone as solvent via NCO-terminated prepolymer. PU actuator was manufactured by stacking carbon black electrode(CBE) at both sides of half cured PU film with spin coater. Compared with conductive grease, displacement using carbon black electrode is approximately 60%. It can be thought that CBE has considerably more viscosity and less conductivity than conductive grease. Although PPy can be made from tens of nanometer to tens of micrometer thickness, phase shift occurs between PU film and PPy because of high temperature CVD process. It is estimated that high surface energy and low surface quality disturbs contacts with PU film.

  1. Robust control of a hydraulically driven flexible arm

    Institute of Scientific and Technical Information of China (English)

    Guang LI; Khajepour AMIR

    2004-01-01

    A new robust controller is proposed to regulate both flexural vibrations and rigid body motion of a hydraulically driven flexible arm. The controller combines backstepping control and sliding mode to arrive at a controller capable of dealing with a nonlinear system with uncertainties. The sliding mode technique is used to achieve an asymptotic joint angle and vibration regulation in the presence of payload uncertainty by providing a virtual torque input at the joint while the backstepping technique is used to regulate the spool position of a hydraulic valve to provide the required torque. It is shown that there is no chatter in the hydraulic valve, which results in smoother operation of the system.

  2. Robust Control of a Hydraulically Actuated Manipulator Using Sliding Mode Control

    DEFF Research Database (Denmark)

    Hansen, Michael Rygaard; Andersen, Torben Ole; Pedersen, Henrik Clemmensen

    2005-01-01

    This paper presents an approach to robust control called sliding mode control (SMC) applied to the a hydraulic servo system (HSS), consisting of a servo valve controlled symmetrical cylinder. The motivation for applying sliding mode control to hydraulically actuated systems is its robustness...... towards structured (parametric) and unstructured (unmodeled dynamics) uncertainties. A third-order model of the actuated system is used to develop a sliding mode control which is implemented and tested on a simulation model. To avoid measurement of velocity and acceleration a simple first-order model...... is furthermore used to develop a simple sliding mode control (SSMC). The performance of the two controllers are compared and discussed....

  3. Flexible and stretchable electrodes for dielectric elastomer actuators

    Science.gov (United States)

    Rosset, Samuel; Shea, Herbert R.

    2013-02-01

    Dielectric elastomer actuators (DEAs) are flexible lightweight actuators that can generate strains of over 100 %. They are used in applications ranging from haptic feedback (mm-sized devices), to cm-scale soft robots, to meter-long blimps. DEAs consist of an electrode-elastomer-electrode stack, placed on a frame. Applying a voltage between the electrodes electrostatically compresses the elastomer, which deforms in-plane or out-of plane depending on design. Since the electrodes are bonded to the elastomer, they must reliably sustain repeated very large deformations while remaining conductive, and without significantly adding to the stiffness of the soft elastomer. The electrodes are required for electrostatic actuation, but also enable resistive and capacitive sensing of the strain, leading to self-sensing actuators. This review compares the different technologies used to make compliant electrodes for DEAs in terms of: impact on DEA device performance (speed, efficiency, maximum strain), manufacturability, miniaturization, the integration of self-sensing and self-switching, and compatibility with low-voltage operation. While graphite and carbon black have been the most widely used technique in research environments, alternative methods are emerging which combine compliance, conduction at over 100 % strain with better conductivity and/or ease of patternability, including microfabrication-based approaches for compliant metal thin-films, metal-polymer nano-composites, nanoparticle implantation, and reel-to-reel production of μm-scale patterned thin films on elastomers. Such electrodes are key to miniaturization, low-voltage operation, and widespread commercialization of DEAs.

  4. Optimum Design of a Moving Coil Actuator for Fast-Switching Valves in Digital Hydraulic Pumps and Motors

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Bech, Michael Møller; Johansen, Per

    2015-01-01

    Fast-switching seat valves suitable for digital hydraulic pumps and motors utilize direct electromagnetic actuators, which must exhibit superior transient performance to allow efficient operation of the fluid power pump/motor. A moving coil actuator resulting in a minimum valve switching time.......5 bar at 600 L/min flow rate, enabling efficient operation of digital hydraulic pumps and motors....

  5. 46 CFR 58.25-60 - Non-duplicated hydraulic rudder actuators.

    Science.gov (United States)

    2010-10-01

    ...) (incorporated by reference, see 46 CFR 58.03-1) and be acceptable to the Commanding Officer, Marine Safety Center. Also, the piping for the main gear must comply with 46 CFR 58.25-10(e)(3). ... 46 Shipping 2 2010-10-01 2010-10-01 false Non-duplicated hydraulic rudder actuators....

  6. Modeling and controlling of a flexible hydraulic manipulator

    Institute of Scientific and Technical Information of China (English)

    LI Guang; WU Min

    2005-01-01

    A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the modeling of interaction between hydraulic circuit and flexible manipulator mechanism. Furthermore, a new robust controller based on mentioned above dynamic model was also considered to regulate both flexural vibrations and rigid body motion. The proposed controller combined sliding mode and backstepping techniques to deal with the nonlinear system with uncertainties. The sliding mode control was used to achieve an asymptotic joint angle and vibration regulation by providing a virtual force while the backstepping technique was used to regulate the spool position of a hydraulic valve to provide the required control force. Simulation results are presented to show the stabilizing effect and robustness of this control strategy.

  7. Aircraft Digital Input Controlled Hydraulic Actuation and Control System.

    Science.gov (United States)

    1981-03-01

    unexplained actuator phase shift with speed is thought to be explained by transient " wire drawing " of flow across the active metering lands of the...rotary valve. This " wire drawing " effect occurs at the time of switching of each cylinder pressure between the load and return pressure states. 169 N~o...the afforementioned upward spread of the performance curves. The major factor in this spread in believed to be the, so called, " wire drawing " at the

  8. Rigid-flexible coupling dynamic modeling and investigation of a redundantly actuated parallel manipulator with multiple actuation modes

    Science.gov (United States)

    Liang, Dong; Song, Yimin; Sun, Tao; Jin, Xueying

    2017-09-01

    A systematic dynamic modeling methodology is presented to develop the rigid-flexible coupling dynamic model (RFDM) of an emerging flexible parallel manipulator with multiple actuation modes. By virtue of assumed mode method, the general dynamic model of an arbitrary flexible body with any number of lumped parameters is derived in an explicit closed form, which possesses the modular characteristic. Then the completely dynamic model of system is formulated based on the flexible multi-body dynamics (FMD) theory and the augmented Lagrangian multipliers method. An approach of combining the Udwadia-Kalaba formulation with the hybrid TR-BDF2 numerical algorithm is proposed to address the nonlinear RFDM. Two simulation cases are performed to investigate the dynamic performance of the manipulator with different actuation modes. The results indicate that the redundant actuation modes can effectively attenuate vibration and guarantee higher dynamic performance compared to the traditional non-redundant actuation modes. Finally, a virtual prototype model is developed to demonstrate the validity of the presented RFDM. The systematic methodology proposed in this study can be conveniently extended for the dynamic modeling and controller design of other planar flexible parallel manipulators, especially the emerging ones with multiple actuation modes.

  9. Optimum vibration control of flexible beams by piezo-electric actuators

    Science.gov (United States)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  10. Optimum vibration control of flexible beams by piezo-electric actuators

    Science.gov (United States)

    Baz, A.; Poh, S.; Studer, P.

    1988-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  11. Integrating a piezoelectric actuator with mechanical and hydraulic devices to control camless engines

    Science.gov (United States)

    Mercorelli, Paolo; Werner, Nils

    2016-10-01

    The paper deals with some interdisciplinary aspects and problems concerning the actuation control which occur in the integration of a piezoelectric structure in an aggregate actuator consisting of a piezoelectric, a stroke ratio displacement, a mechanical and a hydraulic part. Problems like compensation of the piezo hysteresis effect, scaling force-position to obtain an adequate displacement of the actuator and finally the control of such a complex aggregate system are considered and solved. Even though this work considers a particular application, the solutions proposed in the paper are quite general. In fact, the considered technical aspects occurring in systems which utilize piezoelectric technologies can be used in a variegated gamma of actuators integrating piezoelectric technologies. A cascade controller is proposed to combine a Feedforward action with an internal and an external PI-Controller. The Feedforward Controller is based on the model of the whole actuator, so particular attention is paid to the model structure. The resulting Feedforward action is an adaptive one to compensate hydraulic pressure faults. Real measurements are shown.

  12. Optimum shape control of flexible beams by piezo-electric actuators

    Science.gov (United States)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the static deformation and shape of flexible beams is examined. An optimum design procedure is presented to enable the selection of the optimal location, thickness and excitation voltage of the piezoelectric actuators in a way that would minimize the deflection of the beam to which these actuators are bonded. Numerical examples are presented to illustrate the application of the developed optimization procedure in minimizing structural deformation of beams using ceramic and polymeric piezoelectric actuators bonded to the beams with a typical bonding agent. The obtained results emphasize the importance of the devised rational produce in designing beam-actuator systems with minimal elastic distortions.

  13. Design and modeling of a hydraulically amplified magnetostrictive actuator for automotive engine mounts

    Science.gov (United States)

    Chakrabarti, Suryarghya; Dapino, Marcelo J.

    2010-04-01

    A model is developed which describes the dynamic response of a Terfenol-D actuator with a hydraulic displacement amplification mechanism for use in active engine mounts. The model includes three main components: magnetic diffusion, Terfenol-D constitutive model, and mechanical actuator model. Eddy current losses are modeled as a one-dimensional magnetic field diffusion problem in cylindrical coordinates. The Jiles-Atherton model is used to describe the magnetization state of the Terfenol-D driver as a function of applied magnetic fields. A quadratic, single-valued model for the magnetostriction dependence on magnetization is utilized which provides an input to the mechanical model describing the system vibrations. Friction at the elastomeric seals is modeled using the LuGre friction model for lubricated contacts. The actuator's dynamic response is quantified in terms of the output displacement in the unloaded condition and force output in the loaded condition. The model is shown to accurately quantify the dynamic behavior of the actuator over the frequency range considered, from near dc to 500 Hz. An order analysis shows that the model also describes the higher harmonic content present in the measured responses. A study on the variation of energy delivered by the actuator with the load stiffness reveals that the actuator delivers the highest energy output near the stiffness match region.

  14. ROBUST CONTROL OF AN ELECTRO-HYDRAULIC PROPORTIONAL SPEED CONTROL SYSTEM WITH A SINGLE-ROD HYDRAULIC ACTUATOR

    Institute of Scientific and Technical Information of China (English)

    Yang Jian; Xu Bing; Yang Huayong

    2005-01-01

    A robust control algorithm is proposed to focus on the non-linearity and parameters'uncertainties of an electro-hydraulic proportional speed control system (EHPSCS) with a single-rod hydraulic actuator. The robust controller proposed does not need to design stable compensator in advance, is simple in design and has large scope of uncertainty applications. The feedback gains of the robust controller proposed are small, so it is easily implemented in engineering applications.Experimental research on the speed control under the different conditions is carried out for an EHPSCS. Experimental results show that the robust controller proposed has better robustness subject to parametric uncertainties, and adaptability of parameters' variation of control system itself and plant parameter variation.

  15. A Strategy Tackling Local Minimum of Direct Search Method in Modeling a Hydraulic Actuator

    Institute of Scientific and Technical Information of China (English)

    刘云山; 陈晓辉

    2013-01-01

    A strategy for attacking the local minimum problem of direct search method is developed for modeling a hydraulic actuator. The Nelder-Mead direct search method is combined with Ordinary Least Squares which can used to optimize the parameters which the model function is in linear with. The model fitting results show that this strategy can reach a solution more close to the global minimum than the Nelder-Mead direct search method used alone.

  16. System and method for controlling engine knock using electro-hydraulic valve actuation

    Science.gov (United States)

    Brennan, Daniel G

    2013-12-10

    A control system for an engine includes a knock control module and a valve control module. The knock control module adjusts a period that one or more of an intake valve and an exhaust valve of a cylinder are open based on engine knock corresponding to the cylinder. The valve control module, based on the adjusted period, controls the one or more of the intake valve and the exhaust valve using one or more hydraulic actuators.

  17. Space Shuttle Main Engine control system. [hydraulic actuator with digital control

    Science.gov (United States)

    Seitz, P. F.; Searle, R. F.

    1973-01-01

    The Space Shuttle Main Engine is a reusable, high-performance rocket engine being developed by the Rocketdyne Div. of Rockwell International to satisfy the operational requirements of the Space Shuttle Orbiter Vehicle. The design incorporates a hydraulically actuated, closed-loop servosystem controlled and monitored by a programmable electronic digital controller. The controller accepts vehicle commands for the various engine operational phases, positions the appropriate valves, monitors the engine for the required performance precisions and conditions, and provides redundancy management.

  18. Unidirectional variable stiffness hydraulic actuator for load-carrying knee exoskeleton

    Directory of Open Access Journals (Sweden)

    Jun Zhu

    2017-01-01

    Full Text Available This article presents the design and experimental testing of a unidirectional variable stiffness hydraulic actuator for load-carrying knee exoskeleton. The proposed actuator is designed for mimicking the high-efficiency passive behavior of biological knee and providing actively assistance in locomotion. The adjustable passive compliance of exoskeletal knee is achieved through a variable ratio lever mechanism with linear elastic element. A compact customized electrohydraulic system is also designed to accommodate application demands. Preliminary experimental results show the prototype has good performances in terms of stiffness regulation and joint torque control. The actuator is also implemented in an exoskeleton knee joint, resulting in anticipant human-like passive compliance behavior.

  19. Modeling and analysis of a meso-hydraulic climbing robot with artificial muscle actuation.

    Science.gov (United States)

    Chapman, Edward M; Jenkins, Tyler E; Bryant, Matthew

    2017-07-10

    This paper presents a fully coupled electro-hydraulic model of a bio-inspired climbing robot actuated by fluidic artificial muscles (FAMs). This analysis expands upon previous FAM literature by considering not only the force and contraction characteristics of the actuator, but the complete hydraulic and electromechanical circuits as well as the dynamics of the climbing robot. This analysis allows modeling of the time-varying applied pressure, electrical current, and actuator contraction for accurate prediction of the robot motion, energy consumption, and mechanical work output. The developed model is first validated against mechanical and electrical data collected from a proof-of-concept prototype robot. The model is then employed to study the system-level sensitivities of the robot locomotion efficiency and average climbing speed to several design and operating parameters. The results of this analysis demonstrate that considering only the transduction efficiency of the FAM actuators is insufficient to maximize the efficiency of the complete robot, and that a holistic approach can lead to significant improvements in performance. © 2017 IOP Publishing Ltd.

  20. Hydraulically actuated hexapod robots design, implementation and control

    CERN Document Server

    Nonami, Kenzo; Irawan, Addie; Daud, Mohd Razali

    2014-01-01

    Legged robots are a promising locomotion system, capable of performing tasks that conventional vehicles cannot. Even more exciting is the fact that this is a rapidly developing field of study for researchers from a variety of disciplines. However, only a few books have been published on the subject of multi-legged robots. The main objective of this book is to describe some of the major control issues concerning walking robots that the authors have faced over the past 10 years. A second objective is to focus especially on very large hydraulically driven hexapod robot locomotion weighing more than 2,000 kg, making this the first specialized book on this topic. The 10 chapters of the book touch on diverse relevant topics such as design aspects, implementation issues, modeling for control, navigation and control, force and impedance control-based walking, fully autonomous walking, walking and working tasks of hexapod robots, and the future of walking robots. The construction machines of the future will very likel...

  1. Position Control of an Over‐Actuated Direct Hydraulic Cylinder Drive

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Grønkjær, Morten; Pedersen, Henrik Clemmensen

    2017-01-01

    This paper considers the analysis and control strategy for a novel direct hydraulic cylinder drive, that is overactuated in the sense that it has more inputs than sensible outputs. Efforts to overcome the inherent loss of energy due to th+rottling in valve driven hydraulic drives are many......, and various approaches have been proposed by research communities as well as the industry. Recently, a so-called Speed-variable Switched Differential Pump was proposed for direct drive of hydraulic differential cylinders. The main idea with this drive is to utilize an electric rotary drive with the shaft...... the ability to bleed off flow from the transmission lines to achieve reasonable pressure levels. This design renders the drive over-actuated as the line pressures and the cylinder piston motion cannot be controlled independently, due to the pressure difference being motion generating. In order to achieve...

  2. Refurbishing technologies of hydraulic actuators applied in mining industry

    Directory of Open Access Journals (Sweden)

    P. Gendarz

    2010-07-01

    Full Text Available Purpose: of this paper: Mainly, future design and manufacturing processes should be oriented to refurbishing and overhaul, such as mining machines, hydraulics, military industry, heavy industry products, etc.. This paper shows method which can improve indirectly profitability also in environment protection area.Design/methodology/approach: Methodology that solves refurbishing and overhaul problem of application, is based on CAD/CAM integration, and predicts possibility to even prepare design for refurbishing. With help of reverse engineering techniques, also exist approach to refurbish elements that has no overhaul documentation prepared before.Findings: Preparation of overhaul documentation for families of constructions, should be computer aided with use of prepared dedicated software. Time need to prepare refurbishing technology, can be considerably reduced.Research limitations/implications: Refurbishing and overhaul in existence cycle of product should have same rights as technology or design processes. Future development of new refurbishing technologies should be prepared in software combined with CAD/CAM modules used in advanced CAE programs.Practical implications: Mining industry after possible initiate refurbishing methods, can extend exploit time of exerted machines. Simultaneously producers of mining machines and equipment, after bringing in design for refurbishing strategy in to production, can enhance economical profits from maintenance and service time prolongation.Originality/value: For last twenty years no development in area of patents were noticed. That came with increase of consumption strategy progressed by produces. Presented method solves issues of materials raise in prices and relatively short time of maintenance and service time period. New workstations in industry can be created with application of the method.

  3. Hydrodynamic analysis, performance assessment, and actuator design of a flexible tail propulsor in an artificial alligator

    Science.gov (United States)

    Philen, Michael; Neu, Wayne

    2011-09-01

    The overall objective of this research is to develop analysis tools for determining actuator requirements and assessing viable actuator technology for design of a flexible tail propulsor in an artificial alligator. A simple hydrodynamic model that includes both reactive and resistive forces along the tail is proposed and the calculated mean thrust agrees well with conventional estimates of drag. Using the hydrodynamic model forces as an input, studies are performed for an alligator ranging in size from 1 cm to 2 m at swimming speeds of 0.3-1.8 body lengths per second containing five antagonistic pairs of actuators distributed along the length of the tail. Several smart materials are considered for the actuation system, and preliminary analysis results indicate that the acrylic electroactive polymer and the flexible matrix composite actuators are potential artificial muscle technologies for the system.

  4. A flexible metallic actuator using reduced graphene oxide as a multifunctional component.

    Science.gov (United States)

    Meng, Junxing; Mu, Jiuke; Hou, Chengyi; Zhang, Qinghong; Li, Yaogang; Wang, Hongzhi

    2017-09-14

    Flexible actuators are widely in demand for many real-life applications. Considering that existing actuators based on polymers, low-dimensional materials and pore-rich materials are mostly limited by slow response rate, high driving voltage and poor stability, we report here a novel metal based flexible actuator which is fabricated simply through partial oxidation and nano-function of copper foil with the assistance of reduced graphene oxide. The obtained asymmetric metallic actuator is (electric-)thermally driven and exhibits fast response rate (∼2 s) and large curvature (2.4 cm(-1)) under a low voltage (∼1 V) with a sustainable operation of up to ∼50 000 cycles. The actuator can also be triggered by infrared irradiation and direct-heating under various conditions including air, water, and vacuum.

  5. Improvement of Flexible Linear Stepping Actuator Driven by Pneumatic Balloons and Brakes

    Directory of Open Access Journals (Sweden)

    Eguchi Yuya

    2016-01-01

    Full Text Available The development of soft actuator for the rehabilitation device and power assisting devices has been required based on aging society. However, a flexible actuator that can generate both larger force and longer displacement has not been developed. It is also difficult to realize a flexible displacement sensor with long stroke while deforming its form according to the actuator’s shape. In the previous study, the flexible actuator with larger force and longer stroke that can adjust its stroke by giving stepping motion using pneumatic balloons and brakes was proposed and tested. However, the slipping of the pneumatic brake prevents the larger generated force. In this paper, the improved pneumatic brake using a pneumatic balloon and a mechanical chuck is described. The fundamental performance of the actuator using the improved brake is also described.

  6. Suitability of Hydraulic Disk Brakes for Passive Actuation of Upper-Extremity Rehabilitation Exoskeleton

    Directory of Open Access Journals (Sweden)

    Arno H. A. Stienen

    2009-01-01

    Full Text Available Passive, energy-dissipating actuators are promising for force-coordination training in stroke rehabilitation, as they are inherently safe and have a high torque-to-weight ratio. The goal of this study is to determine if hydraulic disk brakes are suitable to actuate an upper-extremity exoskeleton, for application in rehabilitation settings. Passive actuation with friction brakes has direct implications for joint control. Braking is always opposite to the movement direction. During standstill, the measured torque is equal to the torque applied by the human. During rotations, it is equal to the brake torque. Actively assisting movement is not possible, nor are energy-requiring virtual environments. The evaluated disk brake has a 20 Nm bandwidth (flat-spectrum, multi-sine of 10 Hz; sufficient for torques required for conventional therapy and simple, passive virtual environments. The maximum static output torque is 120 Nm, sufficient for isometric training of the upper extremity. The minimal impedance is close zero, with only the inertia of the device felt. In conclusion, hydraulic disk brakes are suitable for rehabilitation devices.

  7. Interval Type-2 fuzzy position control of electro-hydraulic actuated robotic excavator

    Institute of Scientific and Technical Information of China (English)

    Hassan Mohammed Yousif; Kothapalli Ganesh

    2012-01-01

    This paper deals with fuzzy intelligent position control of electro-hydraulic activated robotic excavator for the control of boom,arm and bucket axes.Intelligent control systems are required to overcome undesirable stick-slip motion,limit cycles and oscillations.Models of electro-hydraulic servo controlled front end loader excavators are highly nonlinear.The nonlinear model accounts for fluid flow rate of valve,pump hydraulics,and friction forces.The friction forces are modelled by Coulomb,viscous and Stribeck function.Interval Type-2 Fuzzy Logic Controller (IT2FLC) is used to study the time domain position responses of axes in the presence of external applied load.It has the ability to control the position of eachof the three axes with minimum actuator position errors.Models presented are accurate and study the dynamics of the actuator and load.To improve the transient behaviour of the robotic excavator,we eliminated jitter of the bucket movement in the presence of nonlinearities.

  8. Abrasion test of flexible protective materials on hydraulic structures

    Directory of Open Access Journals (Sweden)

    Xin WANG

    2014-01-01

    Full Text Available In this study, several kinds of flexible protective materials sprayed with polyurea elastomers (hereinafter referred to as polyurea elastomer protective material were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.

  9. Dynamics and design of a power unit with a hydraulic piston actuator

    Science.gov (United States)

    Misyurin, S. Yu.; Kreinin, G. V.

    2016-07-01

    The problem of the preselection of parameters of a power unit of a mechatronic complex on the basis of the condition for providing a required control energy has been discussed. The design of the unit is based on analysis of its dynamics under the effect of a special-type test conditional control signal. The specific features of the approach used are a reasonably simplified normalized dynamic model of the unit and the formation of basic similarity criteria. Methods of designing a power unit with a hydraulic piston actuator that operates in point-to-point and oscillatory modes have been considered.

  10. Position Control of an Over‐Actuated Direct Hydraulic Cylinder Drive

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Grønkjær, Morten; Pedersen, Henrik Clemmensen

    2017-01-01

    This paper considers the analysis and control strategy for a novel direct hydraulic cylinder drive, that is overactuated in the sense that it has more inputs than sensible outputs. Efforts to overcome the inherent loss of energy due to th+rottling in valve driven hydraulic drives are many...... the ability to bleed off flow from the transmission lines to achieve reasonable pressure levels. This design renders the drive over-actuated as the line pressures and the cylinder piston motion cannot be controlled independently, due to the pressure difference being motion generating. In order to achieve...... satisfactory performance of this drive, a state coupling analysis is presented along with a control strategy based on state decoupling synthesized from input-output transformations. This includes control schemes for the transformed system. The proposed control strategy is experimentally verified on a drive...

  11. Static deflection control of flexible beams by piezo-electric actuators

    Science.gov (United States)

    Baz, A. M.

    1986-01-01

    This study deals with the utilization of piezo-electric actuators in controlling the static deformation of flexible beams. An optimum design procedure is presented to enable the selection of the optimal location, thickness and excitation voltage of the piezo-electric actuators in a way that would minimize the deflection of the beam to which these actuators are bonded. Numerical examples are presented to illustrate the application of the developed optimization procedure in minimizing the structural deformation of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezo-electric actuators. The results obtained emphasize the importance of the devised rational procedure in designing beam-actuator systems with minimal elastic distortions.

  12. Analysis of actuating mechanics characteristics for a flexible miniature robot system

    Institute of Scientific and Technical Information of China (English)

    Lianzhi YU; Guozheng YAN; Guanying MA; Peng ZAN

    2008-01-01

    Based on the inchworm movement, a minia-ture endoscope inspection robot system with a flexible structure is designed. The system is actuated by a pneumatic rubber actuator with three degrees of free-dom, and it holds its position by air chambers. The actuating mechanics characteristics of the robot are analyzed. An electro-pneumatic pressure system is designed to control the motion of the robot. Results of the calculation and experiments are consistent, and the robot system can move smoothly in a soft tube.

  13. Modeling of a flexible beam actuated by shape memory alloy wires

    Science.gov (United States)

    Shu, Steven G.; Lagoudas, Dimitris C.; Hughes, Declan; Wen, John T.

    1997-06-01

    A thermomechanical model is developed to predict the structural response of a flexible beam with shape memory alloy (SMA) wire actuators. A geometrically nonlinear static analysis is first carried out to investigate the deformed shape of a flexible cantilever beam caused by an externally-attached SMA wire actuated electrically. The actuation force applied by the SMA actuator to the beam is evaluated by solving a coupled problem that combines a thermodynamic constitutive model of SMAs with the heat conduction equation in the SMA and the structural model of the beam. To calculate the temperature history of the SMA actuator for given electrical current input, the heat transfer equation is solved with the electrical resistive heating being modeled as a distributed heat source along the SMA wire. The steps in the formulation are connected together through an iterative scheme that takes into account the static equilibrium of the beam and the constitutive relation of SMAs, thus translating an electrical current history input into beam strain output. The proposed model is used to simulate the experimental results, thus demonstrating the feasibility of using SMA actuators for shape control of active flexible structural systems.

  14. Extended state observer–based fractional order proportional–integral–derivative controller for a novel electro-hydraulic servo system with iso-actuation balancing and positioning

    Directory of Open Access Journals (Sweden)

    Qiang Gao

    2015-12-01

    Full Text Available Aiming at balancing and positioning of a new electro-hydraulic servo system with iso-actuation configuration, an extended state observer–based fractional order proportional–integral–derivative controller is proposed in this study. To meet the lightweight requirements of heavy barrel weapons with large diameters, an electro-hydraulic servo system with a three-chamber hydraulic cylinder is especially designed. In the electro-hydraulic servo system, the balance chamber of the hydraulic cylinder is used to realize active balancing of the unbalanced forces, while the driving chambers consisting of the upper and lower chambers are adopted for barrel positioning and dynamic compensation of external disturbances. Compared with conventional proportional–integral–derivative controllers, the fractional order proportional–integral–derivative possesses another two adjustable parameters by expanding integer order to arbitrary order calculus, resulting in more flexibility and stronger robustness of the control system. To better compensate for strong external disturbances and system nonlinearities, the extended state observer strategy is further introduced to the fractional order proportional–integral–derivative control system. Numerical simulation and bench test indicate that the extended state observer–based fractional order proportional–integral–derivative significantly outperforms proportional–integral–derivative and fractional order proportional–integral–derivative control systems with better control accuracy and higher system robustness, well demonstrating the feasibility and effectiveness of the proposed extended state observer–based fractional order proportional–integral–derivative control strategy.

  15. Development of Compact Flexible Displacement Sensors Using Ultrasonic Sensor for Wearable Actuators

    Directory of Open Access Journals (Sweden)

    Akagi Tetsuya

    2016-01-01

    Full Text Available In position control of wearable actuator such as a rubber artificial muscle, a compact flexible displacement sensor is much attractive and required. In this paper, two types of flexible displacement sensor using the ultrasonic sensor were introduced. One is a built-in displacement sensor for rubber artificial muscle. Another is a sensor that can measure the sliding displacement on a flexible tube for flexible robot. Both sensors use ultrasonic displacement sensors. The construction, operating principle and measuring performance of two sensors were also described.

  16. Internal Leakage Fault Detection and Tolerant Control of Single-Rod Hydraulic Actuators

    Directory of Open Access Journals (Sweden)

    Jianyong Yao

    2014-01-01

    Full Text Available The integration of internal leakage fault detection and tolerant control for single-rod hydraulic actuators is present in this paper. Fault detection is a potential technique to provide efficient condition monitoring and/or preventive maintenance, and fault tolerant control is a critical method to improve the safety and reliability of hydraulic servo systems. Based on quadratic Lyapunov functions, a performance-oriented fault detection method is proposed, which has a simple structure and is prone to implement in practice. The main feature is that, when a prescribed performance index is satisfied (even a slight fault has occurred, there is no fault alarmed; otherwise (i.e., a severe fault has occurred, the fault is detected and then a fault tolerant controller is activated. The proposed tolerant controller, which is based on the parameter adaptive methodology, is also prone to realize, and the learning mechanism is simple since only the internal leakage is considered in parameter adaptation and thus the persistent exciting (PE condition is easily satisfied. After the activation of the fault tolerant controller, the control performance is gradually recovered. Simulation results on a hydraulic servo system with both abrupt and incipient internal leakage fault demonstrate the effectiveness of the proposed fault detection and tolerant control method.

  17. Adaptive Finite-Time Control for a Flexible Hypersonic Vehicle with Actuator Fault

    Directory of Open Access Journals (Sweden)

    Jie Wang

    2013-01-01

    Full Text Available The problem of robust fault-tolerant tracking control is investigated. Simulation on the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV with actuator faults and uncertainties is conducted. In order to guarantee that the velocity and altitude track their desired commands in finite time with the partial loss of actuator effectiveness, an adaptive fault-tolerant control strategy is presented based on practical finite-time sliding mode method. The adaptive update laws are used to estimate the upper bound of uncertainties and the minimum value of actuator efficiency factor. Finally, simulation results show that the proposed control strategy is effective in rejecting uncertainties even in the presence of actuator faults.

  18. Biomimetic flexible plate actuators are faster and more efficient with a passive attachment

    Science.gov (United States)

    Yeh, Peter D.; Alexeev, Alexander

    2016-12-01

    Using three-dimensional computer simulations, we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency. The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric macro fiber composite (MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.

  19. Internally-actuated flexible fins swim faster and more efficiently with a passive attachment

    Science.gov (United States)

    Yeh, Peter; Alexeev, Alexander

    2016-11-01

    Using three dimensional computer simulations, we probe biomimetic free swimming of an internally-actuated flexible plate in the regime near the first natural frequency. The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric MFC bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.

  20. A Novel Implementation of a Flexible Robotic Fin Actuated by Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Qin Yan; Lei Wang; Bo Liu; Jie Yang; Shiwu Zhang

    2012-01-01

    In this paper,study of a novel flexible robotic-fin actuated by Shape Memory Alloy (SMA) is presented.The developed robotic fin is capable of implementing various 3-Dimensional (3D) motions,which plays an important role in robot propulsion and maneuverability.Firstly,the morphological and mechanics parameters of a real pectoral fin from a carp are investigated.Secondly,a detailed design of the flexible pectoral fin driven by SMA is presented according to the previous morphological and mechanics analyses.Thirdly,a simplified theoretical model on the SMA fin plate is derived.The thermodynamics of the SMA plate and the relationship between curvature and phase transformation are analyzed.Finally,several simulations and model experiments are conducted according to the previous analyses.The results of the experiments are useful for the control of the robotic fin.The experimental results reveal that the SMA actuated fin ray has a good actuating performance.

  1. Recurrent-neural-network-based identification of a cascade hydraulic actuator for closed-loop automotive power transmission control

    Energy Technology Data Exchange (ETDEWEB)

    You, Seung Han [Hyundai Motor Company, Seoul (Korea, Republic of); Hahn, Jin Oh [University of Alberta, Edmonton (Canada)

    2012-05-15

    By virtue of its ease of operation compared with its conventional manual counterpart, automatic transmissions are commonly used as automotive power transmission control system in today's passenger cars. In accordance with this trend, research efforts on closed-loop automatic transmission controls have been extensively carried out to improve ride quality and fuel economy. State-of-the-art power transmission control algorithms may have limitations in performance because they rely on the steady-state characteristics of the hydraulic actuator rather than fully exploit its dynamic characteristics. Since the ultimate viability of closed-loop power transmission control is dominated by precise pressure control at the level of hydraulic actuator, closed-loop control can potentially attain superior efficacy in case the hydraulic actuator can be easily incorporated into model-based observer/controller design. In this paper, we propose to use a recurrent neural network (RNN) to establish a nonlinear empirical model of a cascade hydraulic actuator in a passenger car automatic transmission, which has potential to be easily incorporated in designing observers and controllers. Experimental analysis is performed to grasp key system characteristics, based on which a nonlinear system identification procedure is carried out. Extensive experimental validation of the established model suggests that it has superb one-step-ahead prediction capability over appropriate frequency range, making it an attractive approach for model-based observer/controller design applications in automotive systems.

  2. Design of a Magnetostrictive-Hydraulic Actuator Considering Nonlinear System Dynamics and Fluid-Structure Coupling

    Science.gov (United States)

    Larson, John Philip

    Smart material electro-hydraulic actuators (EHAs) utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of certain smart materials into large motions of a hydraulic cylinder. Although the concept has been demonstrated in previously, the operating frequency of smart material EHA systems has been limited to a small fraction of the available bandwidth of the driver materials. The focus of this work is to characterize and model the mechanical performance of a magnetostrictive EHA considering key system components: rectification valves, smart material driver, and fluid-system components, leading to an improved actuator design relative to prior work. The one-way valves were modeled using 3-D finite element analysis, and their behavior was characterized experimentally by static and dynamic experimental measurement. Taking into account the effect of the fluid and mechanical conditions applied to the valves within the pump, the dynamic response of the valve was quantified and applied to determine rectification bandwidth of different valve configurations. A novel miniature reed valve, designed for a frequency response above 10~kHz, was fabricated and tested within a magnetostrictive EHA. The nonlinear response of the magnetostrictive driver, including saturation and hysteresis effects, was modeled using the Jiles-Atherton approach to calculate the magnetization and the resulting magnetostriction based on the applied field calculated within the rod from Maxwell's equations. The dynamic pressure response of the fluid system components (pumping chamber, hydraulic cylinder, and connecting passages) was measured over a range of input frequencies. For the magnetostrictive EHA tested, the peak performance frequency was found to be limited by the fluid resonances within the system. A lumped-parameter modeling approach was applied to model the overall behavior of a magnetostrictive EHA, incorporating models for the reed valve response

  3. A Study on the Air Vent Valve of the Hydraulic Servo Actuator for Steam Control of Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Bum; Lee, Jong Jik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2016-06-15

    To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

  4. Roll maneuvering of flexible aircraft with distributed-parameter actuation via modal synthesis

    Science.gov (United States)

    Oz, Hayrani; Khot, Narendra S.

    1999-06-01

    The focus is on obtaining and identifying optimal distributed- parameter-control equivalent actuation profiles for desired roll maneuvers by a modal synthesis approach. The solution for distributed-parameter-control of an aeroelastic system is developed by synthesis of modal-state-space controllers designed via the globally power optimal Independent Modal- Space Control (IMSC) technique. The desired maneuver (set- point) control performance is achieved by a modal-performance- output synthesis (MPOS) approach. The MPOS approach requires that each independent modal controller be allocated a desired portion of the total desired output performance. In view of this, a modal performance-output allocation optimization problem is also defined, which minimizes a hybrid measure of control power and elastic strain energy of the structure during aeroelastic control. Insight to distributed-parameter- control equivalent actuation solutions are sought by considering the aeroservoelastic interactions among vehicle motion, aerodynamics, structural flexibility and control actuators from the perspective of work-energy, control power, and control loading requirements. The modal synthesis approach is illustrated for a flight vehicle wing design to achieve a 90 deg/sec roll-rate in a Mach 2 flight condition at altitude (20000 ft) via distributed-parameter equivalent actuation. The preliminary results indicate that such a roll-rate maneuver can be accomplished via distributed-parameter actuation with feasible levels of control power, work-energy, and control loadings through eliciting favorable aeroservoelastic interactions.

  5. The smart Peano fluidic muscle: a low profile flexible orthosis actuator that feels pain

    Science.gov (United States)

    Veale, Allan J.; Anderson, Iain A.; Xie, Shane Q.

    2015-03-01

    Robotic orthoses have the potential to provide effective rehabilitation while overcoming the availability and cost constraints of therapists. These orthoses must be characterized by the naturally safe, reliable, and controlled motion of a human therapist's muscles. Such characteristics are only possible in the natural kingdom through the pain sensing realized by the interaction of an intelligent nervous system and muscles' embedded sensing organs. McKibben fluidic muscles or pneumatic muscle actuators (PMAs) are a popular orthosis actuator because of their inherent compliance, high force, and muscle-like load-displacement characteristics. However, the circular cross-section of PMA increases their profile. PMA are also notoriously unreliable and difficult to control, lacking the intelligent pain sensing systems of their biological muscle counterparts. Here the Peano fluidic muscle, a new low profile yet high-force soft actuator is introduced. This muscle is smart, featuring bioinspired embedded pressure and soft capacitive strain sensors. Given this pressure and strain feedback, experimental validation shows that a lumped parameter model based on the muscle geometry and material parameters can be used to predict its force for quasistatic motion with an average error of 10 - 15N. Combining this with a force threshold pain sensing algorithm sets a precedent for flexible orthosis actuation that uses embedded sensors to prevent damage to the actuator and its environment.

  6. Motion and vibration control of a slewing flexible structure by SMA actuators and parameter sensitivity analysis

    Science.gov (United States)

    Janzen, F. C.; Tusset, A. M.; Piccirillo, V.; Balthazar, J. M.; Brasil, R. M. L. R. F.

    2015-11-01

    This work presents two approaches to the problem of vibration and positioning control of a flexible structural beam driven by a DC motor. The position is controlled by the current applied to the DC motor armature. A Shape Memory Alloy (SMA) actuator controls vibrations of the flexible structural beam. The State Dependent Riccati Equation (SDRE) technique is used to provide a control action which uses sub-optimal control and system local stability search. The robustness of these two controllers is tested by sensitivity analysis to parametric uncertainties. Numerical simulations results are presented to demonstrate the effectiveness of the proposed control strategy.

  7. A fuzzy robust control scheme for vibration suppression of a nonlinear electromagnetic-actuated flexible system

    Science.gov (United States)

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

    2017-03-01

    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.

  8. 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

    2003-01-01

    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.

  9. Effects of Geometrical Clearances, Supports Friction, and Wear Rings on Hydraulic Actuators Bending Behavior

    Directory of Open Access Journals (Sweden)

    Sergio Baragetti

    2016-01-01

    Full Text Available Hydraulic actuators are commonly adopted in machines and structures to provide translating forces with significant magnitudes. Although their application dates back to the industrial revolution, their bending behavior under compression is typically addressed by simple Euler’s instability analysis on the rod, neglecting effects such as the cylinder inertia and stiffness, the presence of contact elements in the cylinder-rod junction and on the piston, geometrical misalignments and imperfections, and friction moments at the support. Such simplifications lead to unjustified reduced critical load calculations on the component. In the present paper, a complete mathematical formulation, which accounts for such effects, is presented and validated against experimental data. A numerical sensitivity analysis is conducted, to assess the contributions of initial rectilinear imperfections, wear rings stiffness and dimension, and supports friction on the actuator’s limit buckling load and bending behavior under compression. Results are presented, including the effect of the cited parameters on the buckling load, providing a reliable tool for the mechanical designer. In particular, an optimum position for the wear ring distance is found. Moreover, increased wear ring stiffness and reduced imperfections increase the buckling load and reduce the bending stresses before the critical load.

  10. Evaluation of a dynamic armrest for hydraulic-actuation controller use.

    Science.gov (United States)

    Murphy, T; Oliver, M L

    2011-07-01

    The efficacy of a newly designed dynamic armrest was evaluated during joystick operation of a typical North American hydraulic-actuation joystick. The dynamic design was evaluated against a stationary armrest condition as well as no armrest condition. Electromyography (EMG) and subjective measurements were used to make the evaluation. The dynamic armrest, which mimics the natural pendulation of a joystick operator's arm in the forward and backward directions, was shown to significantly decrease the muscular activation in the upper trapezius, posterior deltoid, and anterior deltoid (p ≤ 0.01) over a stationary armrest. A questionnaire revealed that subjects significantly (p = 0.01) preferred the dynamic armrest design over either a standard armrest or no armrest with 17 of 21 operators preferring the dynamic armrest. Ratings from the questionnaire indicated that subjects felt that the dynamic armrest required less effort, was more comfortable, and was more effective than either of the other two armrest conditions. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  11. Morphing nacelle inlet lip with pneumatic actuators and a flexible nano composite sandwich panel

    Science.gov (United States)

    Gulsine Ozdemir, Nazli; Scarpa, Fabrizio; Craciun, Monica; Remillat, Chrystel; Lira, Cristian; Jagessur, Yogesh; Da Rocha-Schmidt, Luiz

    2015-12-01

    We present a hybrid pneumatic/flexible sandwich structure with thermoplastic (TP) nanocomposite skins to enable the morphing of a nacelle inlet lip. The design consists of pneumatic inflatables as actuators and a flexible sandwich panel that morphs under variable pressure combinations to adapt different flight conditions and save fuel. The sandwich panel forms the outer layer of the nacelle inlet lip. It is lightweight, compliant and impact resistant with no discontinuities, and consists of graphene-doped thermoplastic polyurethane (G/TPU) skins that are supported by an aluminium Flex-core honeycomb in the middle, with near zero in-plane Poisson’s ratio behaviour. A test rig for a reduced-scale demonstrator was designed and built to test the prototype of morphing nacelle with custom-made pneumatic actuators. The output force and the deflections of the experimental demonstrator are verified with the internal pressures of the actuators varying from 0 to 0.41 MPa. The results show the feasibility and promise of the hybrid inflatable/nanocomposite sandwich panel for morphing nacelle airframes.

  12. Optimal vibration control and co-design of very flexible actuated structures

    Science.gov (United States)

    Maraniello, S.; Palacios, R.

    2016-09-01

    The single shooting method is applied to the optimal control and combined structural and control design (co-design) of very flexible beams. The objective is to assess feasibility, advantages and limitations of an integrated design approach when dealing with actuated structures exhibiting large oscillations and, more generally, strongly nonlinear couplings. A gradient based approach is proposed for the large design space defined by both the optimal control and co-design problems. Numerical studies are presented for the case of a very flexible actuated pendulum with large rigid-body motion. The impact of local (B-splines) and global (discrete sines) set of basis functions is investigated for increasing levels of actuation authority, showing the importance of the time-frequency resolution of the parametrisation on the convergence properties and outcome quality of the process. Locking between control and structural disciplines around specific design points is found, thus highlighting the disadvantage of a sequential design approach. Simultaneous designing of control law and structure is seen, instead, to explore efficiently larger regions of the design space.

  13. Apu/hydraulic/actuator Subsystem Computer Simulation. Space Shuttle Engineering and Operation Support, Engineering Systems Analysis. [for the space shuttle

    Science.gov (United States)

    1975-01-01

    Major developments are examined which have taken place to date in the analysis of the power and energy demands on the APU/Hydraulic/Actuator Subsystem for space shuttle during the entry-to-touchdown (not including rollout) flight regime. These developments are given in the form of two subroutines which were written for use with the Space Shuttle Functional Simulator. The first subroutine calculates the power and energy demand on each of the three hydraulic systems due to control surface (inboard/outboard elevons, rudder, speedbrake, and body flap) activity. The second subroutine incorporates the R. I. priority rate limiting logic which limits control surface deflection rates as a function of the number of failed hydraulic. Typical results of this analysis are included, and listings of the subroutines are presented in appendicies.

  14. Vibration Control of Manipulators with Flexible Nonprismatic Links Using Piezoelectric Actuators and Sensors

    Directory of Open Access Journals (Sweden)

    Valdecir Bottega

    2009-01-01

    robotic manipulator using simultaneously motor torques and piezoelectric actuators. The dynamic model of the flexible manipulator is obtained in a closed form through the Lagrange equations. The control uses the motor torques for the joints tracking control and also to reduce the low-frequency vibration induced in the manipulator links. The stability of this control is guaranteed by the Lyapunov stability theory. Piezoelectric actuators and sensors are added for controlling vibrations with frequencies beyond the reach of motor torque control. The naturals frequencies are calculated by the finite element method, and the approximated eigenfunctions are interpolated by polynomials. Three eigenfunctions are used for the dynamics of the arm, while only two are used for the control. Numerical experiments on Matlab/Simulink are used to verify the efficiency of the control model.

  15. A COMPUTATIONAL STUDY OF THE ACTUATION SPEED OF THE HYDRAULIC CYLINDER UNDER DIFFERENT PORTS’ SIZES AND CONFIGURATIONS

    Directory of Open Access Journals (Sweden)

    M. O. ABDALLA

    2015-02-01

    Full Text Available The discharged oil from hydraulic cylinder, during its operation, is highly restricted by the small sized outlets. As a result, a back pressure builds up and the piston motion, therefore, is slowed down; the system pump has to do additional work to overcome this hydraulic resistance so as to preserve the required speed. In this study the possibility of improvement of the actuation speed of the hydraulic cylinders was investigated and analysed. Both a four-port cylinder and a resized-ports cylinder were proposed as fast cylinders. FLUENT 6.3 was used for the simulation of the oil flow field of the hydraulic cylinders. Results showed that relation between discharge flow and the outlets diameters is best described by a power law having coefficients partially depending on the system pressure. It had also shown that for any given total outlet area, the actuation speed of the single outlet cylinders is always higher than that of the double outlets cylinders. In one case where the total outlet area is 3.93E-05m2, the actuation speed of the single outlet cylinder is 21% higher than that of the double outlets cylinder; whereas, when doubling the total outlet area the different is reduced to just 6% . Resizing the outlet for small ports was more efficient than using multi-outlets; while for a large ports it shows no significant difference to use either one outlet port or multi-outlets. Both the solutions of resizing or ports addition need special valve to be fit to the cylinder so that the cylinder could be effectively operated under the control of the proportional valve.

  16. Simultaneous Investigation of Flexibility and Plasma Actuation Effects on the Aerodynamic Characteristics of an Oscillating Airfoil

    Directory of Open Access Journals (Sweden)

    Arash Mahboubi Doust

    2016-01-01

    Full Text Available In this work, a numerical study of two dimensional laminar incompressible flow around the flexible oscillating NACA0012 airfoil is performed using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping is considered. Reynolds number for these motions is assumed fixed at 12000. One of the important issues that must be considered in designing air structures, in particular the aircraft wing, is the interaction between the air and the elastic aircraft wings that is known as the Aeroelastic phenomenon. For this purpose, the effect of airfoil flexibility and flow induced vibration in these motion types is investigated and compared with the case of rigid airfoil. It is observed that the flexibility in both types of motions causes improvement of the thrust which is boosted with increasing the frequency. Contrary to thrust, the significant improvement of lift is only achievable in high frequencies. It was also found that the effect of flexibility on the flapping motion is higher than the pitching motion. For flow control on the airfoil, Dielectric Barrier Discharge plasma actuator is used in the trailing edge of a flexible airfoil, and its effect on the flexible airfoil is also investigated.

  17. Effect of stiffness and movement speed on selected dynamic torque characteristics of hydraulic-actuation joystick controls for heavy vehicles.

    Science.gov (United States)

    Oliver, Michele; Rogers, Robert; Rickards, Jeremy; Tingley, Maureen; Biden, Edmund

    2006-02-22

    The purpose of this work was to quantify the effects of joystick stiffness and movement speed on the dynamic torque characteristics of hydraulic-actuation joystick controls, as found in off-road vehicles, as one of the initial steps towards the development of a joystick design protocol. Using a previously developed mathematical model in which a hydraulic-actuation joystick is assumed to rotate about two axes where the rotation origin is a universal joint, the dynamic torque characteristics incurred by an operator were predicted. Utilizing a laboratory mock-up of an excavator cab environment, three actuation torque characteristics (peak torque, angular impulse and deceleration at the hard endpoint) were quantified for nine unskilled joystick operators during the use of a commonly used North American hydraulic-actuation joystick. The six different experimental conditions included combinations of three joystick stiffnesses and two movement speeds. The highest instantaneous input torque over the course of the joystick movement (not including the hard endpoint) was evaluated using the peak torque value. Angular impulse provided an indication of the sustained exposure to force. The third indicator, deceleration at the hard endpoint, was included to provide a description of impact loading on the hand as the joystick came to a sudden stop. The most important result of this work is that the dynamic torque characteristics incurred during hydraulic-actuation joystick use are substantial. While the peak torque values were not very different between the fast and slow motion conditions, the high decelerations even for slow movements observed at maximum excursion of the joystick indicate that the dynamics do matter. On the basis of deceleration at the hard endpoint and peak torque, the joystick movements that require the highest values for a combination of torque variables are the side-to-side ones. This suggests that less stiff balance and return springs should be considered for

  18. Improving actuation efficiency through variable recruitment hydraulic McKibben muscles: modeling, orderly recruitment control, and experiments.

    Science.gov (United States)

    Meller, Michael; Chipka, Jordan; Volkov, Alexander; Bryant, Matthew; Garcia, Ephrahim

    2016-11-03

    Hydraulic control systems have become increasingly popular as the means of actuation for human-scale legged robots and assistive devices. One of the biggest limitations to these systems is their run time untethered from a power source. One way to increase endurance is by improving actuation efficiency. We investigate reducing servovalve throttling losses by using a selective recruitment artificial muscle bundle comprised of three motor units. Each motor unit is made up of a pair of hydraulic McKibben muscles connected to one servovalve. The pressure and recruitment state of the artificial muscle bundle can be adjusted to match the load in an efficient manner, much like the firing rate and total number of recruited motor units is adjusted in skeletal muscle. A volume-based effective initial braid angle is used in the model of each recruitment level. This semi-empirical model is utilized to predict the efficiency gains of the proposed variable recruitment actuation scheme versus a throttling-only approach. A real-time orderly recruitment controller with pressure-based thresholds is developed. This controller is used to experimentally validate the model-predicted efficiency gains of recruitment on a robot arm. The results show that utilizing variable recruitment allows for much higher efficiencies over a broader operating envelope.

  19. Numerical and Experimental Modal Control of Flexible Rotor Using Electromagnetic Actuator

    Directory of Open Access Journals (Sweden)

    Edson Hideki Koroishi

    2014-01-01

    Full Text Available The present work is dedicated to active modal control applied to flexible rotors. The effectiveness of the corresponding techniques for controlling a flexible rotor is tested numerically and experimentally. Two different approaches are used to determine the appropriate controllers. The first uses the linear quadratic regulator and the second approach is the fuzzy modal control. This paper is focused on the electromagnetic actuator, which in this case is part of a hybrid bearing. Due to numerical reasons it was necessary to reduce the size of the model of the rotating system so that the design of the controllers and estimator could be performed. The role of the Kalman estimator in the present contribution is to estimate the modal states of the system and to determine the displacement of the rotor at the position of the hybrid bearing. Finally, numerical and experimental results demonstrate the success of the methodology conveyed.

  20. Trajectory tracking and vibration control in a space frame flexible structure with a PZT stack actuator

    Science.gov (United States)

    Garcia-Perez, Oscar A.; Silva-Navarro, G.; Peza-Solís, J. F.; Trujillo-Franco, L. G.

    2015-04-01

    This work deals with the robust asymptotic output tracking control problem of the tip position of a space frame flexible structure, mounted on a rigid revolute servomechanism actuated and controlled with a dc motor. The structure is also affected by undesirable vibrations due to excitation of its first lateral vibration modes and possible variations of the tip mass. The overall flexible structure is modeled by using finite element methods and this is validated via experimental modal analysis techniques. The tip position of the structure is estimated from acceleration and strain gauge measurements. The asymptotic output tracking problem is formulated and solved by means of Passivity-Based and Sliding-Mode Control techniques, applied to the dc motor coupled to the rigid part of the structure, and those undesirable vibrations are simultaneously attenuated by an active vibration control using Positive Position Feedback control schemes implemented on a PZT stack actuator properly located into the mechanical structure. The investigation also addresses the trajectory tracking problem of fast motions, with harmonic excitations close to the first vibration modes of the structure. The overall dynamic performance is evaluated and validated by numerical and experimental results.

  1. Modelling of Moving Coil Actuators in Fast Switching Valves Suitable for Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller

    2015-01-01

    an estimation of the eddy currents generated in the actuator yoke upon current rise, as they may have significant influence on the coil current response. The analytical model facilitates fast simulation of the transient actuator response opposed to the transient electro-magnetic finite element model which...

  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

    2014-01-01

    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. Intelligent Hydraulic Actuator and Exp-based Modelling of Losses in Pumps and .

    DEFF Research Database (Denmark)

    Zhang, Muzhi

    A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed.......A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed....

  4. Hydraulics.

    Science.gov (United States)

    Decker, Robert L.; Kirby, Klane

    This curriculum guide contains a course in hydraulics to train entry-level workers for automotive mechanics and other fields that utilize hydraulics. The module contains 14 instructional units that cover the following topics: (1) introduction to hydraulics; (2) fundamentals of hydraulics; (3) reservoirs; (4) lines, fittings, and couplers; (5)…

  5. Intelligent Hydraulic Actuator and Exp-based Modelling of Losses in Pumps and .

    DEFF Research Database (Denmark)

    Zhang, Muzhi

    A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed....

  6. Softened and flexible biodegradable poly(lactic acid) and its electromechanical properties for actuator application.

    Science.gov (United States)

    Thummarungsan, Natlita; Pattavarakorn, Datchanee; Sirivat, Anuvat

    2016-12-01

    Poly (lactic acid) (PLA) is a biodegradable polymer with high stiffness presenting a limitation for using in actuator applications. Adding a plasticizer is one way to solve this problem to enhance flexibility and improve electromechanical properties of pristine PLA. In this work, the PLA films were prepared via a simple solvent casting method. The influences of plasticizer type and electric field strength on electromechanical behavior of PLA films were investigated by the melt rheometer and bending measurement. For the PLA films filled with dibutyl phthalate (DBP), the storage modulus, G', immediately increased towards its steady state and rapidly recovered to its original value with and without electric field, respectively, which can be referred to a reversible system. On the other hand, the PLA film with Tween 20 processed the highest ∆G׳/G׳0 of 1.34 due to the available amount of polarized groups. In the bending measurement, the dielectrophoresis forces of plasticized PLA films were found to increase with increasing electric field where the deflections occurred towards anode side as the polarized groups generated negative charges. The DBP_PLA1.5D film exhibited the greatest bending and dielectrophoresis force. Thus, the biodegradable PLA along with DBP combine to have a great potential towards actuator application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Experimental Parametric Identification of a Flexible Beam Using Piezoelectric Sensors and Actuators

    Directory of Open Access Journals (Sweden)

    Sajad Saraygord Afshari

    2014-01-01

    Full Text Available Experimental system identification of a flexible beam based on sweep square excitation is studied. For the purpose of nonparametric identification, an excitation signal is conducted to evaluate the frequency response of the system. The experiment is designed to excite the beam using a piezo actuator, in a way to raise the chance of exciting first three natural modes. In order to find the best linear representation of the real system, two different identification methods are applied. First, autoregressive moving average eXogenous method is employed to identify the transfer function of the beam. Then, the identification is carried out using the subspace identification method to obtain the state space model. A comparison is made between different orders of prediction and the best chosen models of the two identification methods are compared with each other to select the most accurate linear system. Furthermore, as the identified model has to fulfill the controllability and observability conditions, the amenable system is achieved after some order reductions. Two reduction methods called minimum truncation and maximum DC gains matching are utilized to find the most effective reduced order. The outcome of this study will bring in the best linear representation of the beam coupled with piezoelectric sensors/actuators.

  8. A Flight Dynamics Model for a Multi-Actuated Flexible Rocket Vehicle

    Science.gov (United States)

    Orr, Jeb S.

    2011-01-01

    A comprehensive set of motion equations for a multi-actuated flight vehicle is presented. The dynamics are derived from a vector approach that generalizes the classical linear perturbation equations for flexible launch vehicles into a coupled three-dimensional model. The effects of nozzle and aerosurface inertial coupling, sloshing propellant, and elasticity are incorporated without restrictions on the position, orientation, or number of model elements. The present formulation is well suited to matrix implementation for large-scale linear stability and sensitivity analysis and is also shown to be extensible to nonlinear time-domain simulation through the application of a special form of Lagrange s equations in quasi-coordinates. The model is validated through frequency-domain response comparison with a high-fidelity planar implementation.

  9. Hydraulic manipulator research at ORNL

    Energy Technology Data Exchange (ETDEWEB)

    Kress, R.L.; Jansen, J.F. [Oak Ridge National Lab., TN (United States); Love, L.J. [Oak Ridge Inst. for Science and Education, TN (United States)

    1997-03-01

    Recently, task requirements have dictated that manipulator payload capacity increase to accommodate greater payloads, greater manipulator length, and larger environmental interaction forces. General tasks such as waste storage tank cleanup and facility dismantlement and decommissioning require manipulator life capacities in the range of hundreds of pounds rather than tens of pounds. To meet the increased payload capacities demanded by present-day tasks, manipulator designers have turned once again to hydraulics as a means of actuation. In order to successfully design, build, and deploy a new hydraulic manipulator (or subsystem), sophisticated modeling, analysis, and control experiments are usually needed. Oak Ridge National Laboratory (ORNL) has a history of projects that incorporate hydraulics technology, including mobile robots, teleoperated manipulators, and full-scale construction equipment. In addition, to support the development and deployment of new hydraulic manipulators, ORNL has outfitted a significant experimental laboratory and has developed the software capability for research into hydraulic manipulators, hydraulic actuators, hydraulic systems, modeling of hydraulic systems, and hydraulic controls. The purpose of this article is to describe the past hydraulic manipulator developments and current hydraulic manipulator research capabilities at ORNL. Included are example experimental results from ORNL`s flexible/prismatic test stand.

  10. Development of a flexible and bendable vibrotactile actuator based on wave-shaped poly(vinyl chloride)/acetyl tributyl citrate gels for wearable electronic devices

    Science.gov (United States)

    Park, Won-Hyeong; Bae, Jin Woo; Shin, Eun-Jae; Kim, Sang-Youn

    2016-11-01

    The paradigm of consumer electronic devices is being shifted from rigid hand-held devices to flexible/wearable devices in search of benefits such as enhanced usability and portability, excellent wear characteristics, and more functions in less space. However, the fundamental incompatibility of flexible/wearable devices and a rigid actuator brought forth a new issue obstructing commercialization of flexible/wearable devices. In this paper, we propose a new wave-shaped eco-friendly PVC gel, and a new flexible and bendable vibrotactile actuator that could easily be applied to wearable electronic devices. We explain the vibration mechanism of the proposed vibrotactile actuator and investigate its influence on the content of plasticizer for the performance of the proposed actuator. An experiment for measuring vibrational amplitude was conducted over a wide frequency range. The experiment clearly showed that the proposed vibrotactile actuator could create a variety of haptic sensations in wearable devices.

  11. Parametric adaptive estimation and backstepping control of electro-hydraulic actuator with decayed memory filter.

    Science.gov (United States)

    Guo, Qing; Sun, Ping; Yin, Jing-Min; Yu, Tian; Jiang, Dan

    2016-05-01

    Some unknown parameter estimation of electro-hydraulic system (EHS) should be considered in hydraulic controller design due to many parameter uncertainties in practice. In this study, a parametric adaptive backstepping control method is proposed to improve the dynamic behavior of EHS under parametric uncertainties and unknown disturbance (i.e., hydraulic parameters and external load). The unknown parameters of EHS model are estimated by the parametric adaptive estimation law. Then the recursive backstepping controller is designed by Lyapunov technique to realize the displacement control of EHS. To avoid explosion of virtual control in traditional backstepping, a decayed memory filter is presented to re-estimate the virtual control and the dynamic external load. The effectiveness of the proposed controller has been demonstrated by comparison with the controller without adaptive and filter estimation. The comparative experimental results in critical working conditions indicate the proposed approach can achieve better dynamic performance on the motion control of Two-DOF robotic arm.

  12. A New Type of Hydraulic Muscle

    Directory of Open Access Journals (Sweden)

    Nitai Drimer

    2016-01-01

    Full Text Available This paper presents the invention and development of a new fundamental type of hydraulic actuator, aimed at delivering better actuation efficiency. This actuator is a flexible tube, composed of two different materials, which deflects while applying inner pressure. This concept is simple to produce, and allows adaptation of the deflected shape by the design parameters (radius, wall thickness, geometry, etc.. Among other applications, it is mostly suitable for the activation of fins of nature-like marine robots. Theoretical formulation, production of prototypes and actuation experiments are presented, as well as material hysteresis research and an application example.

  13. Effect of joystick stiffness, movement speed and movement direction on joystick and upper limb kinematics when using hydraulic-actuation joystick controls in heavy vehicles.

    Science.gov (United States)

    Oliver, M; Tingley, M; Rogers, R; Rickards, J; Biden, E

    2007-06-01

    Despite the widespread use of hydraulic-actuation joysticks in mobile North American construction, mining and forestry vehicles, the biomechanical effects that joysticks have on their human operators has not been studied extensively. Using nine unskilled joystick operators and a laboratory mock-up with a commonly used North American heavy off-road equipment hydraulic-actuation joystick and operator seat, the purpose of this work was to quantify and compare the effects of three hydraulic-actuation joystick stiffnesses and two movement speeds on upper limb and joystick kinematics as one of the initial steps towards the development of a hydraulic-actuation joystick design protocol. In addition to providing a detailed description of the kinematics of a constrained occupational task, coupled with the corresponding effects of the task on operator upper limb kinematics, results from principal component analysis and ANOVA procedures revealed a number of differences in joystick and upper limb angle ranges and movement curve shapes resulting from the various joystick stiffness-speed combinations tested. For the most part, these joystick motion alterations were caused by small, insignificant changes in one or more upper limb joint angles. The two exceptions occurred for forward movements of the joystick; the fast speed - light stiffness condition movement pattern shape change was caused primarily by an alteration of the elbow flexion-extension movement pattern. Similarly, the fast speed - normal stiffness condition movement curve shape perturbation - was caused principally by a combination of significant movement curve shape alterations to elbow flexion-extension, external-internal shoulder rotation and flexion-extension of the shoulder. The finding that joystick stiffness and speed alterations affect joystick and upper limb kinematics minimally indicates that the joystick design approach of modelling the joystick and operator upper limb as a closed linkage system should be

  14. Analysing the Hydraulic Actuator-based Knee Unit Kinematics and Correlating the Numerical Results and Walking Human Knee Joint Behavior

    Directory of Open Access Journals (Sweden)

    K. A. Trukhanov

    2014-01-01

    Full Text Available State-of-the-art machinery development enables people with lost lower limb to continue their previous life despite a loss. International companies dealing with this area pursue a minimization of human behaviour problems because of amputation. Researches to create an optimal design of the artificial knee joint are under way.The work task was to define analytical relationships of changing kinematic parameters of the human walking on the flat surface such as an angle of the knee joint, knee point (moment, definition of reduced knee actuator (A load, as well as to compare obtained results with experimental data.As an A in created design, the article proposes to use a controlled shock absorber based on the hydraulic cylinder.A knee unit is a kinematic two-tier mechanism. One of the mechanism links performs rotational motion, and the other is rotation-translational to provide a rotation of the first one.When studying the hydraulic actuator device dynamics, as a generalized coordinate a coordinate of the piston x (or ρ position is chosen while in the study of link movements an angle β is preferable.Experimental data are obtained for a human with the body weight of 57.6 kg walking on the flat surface to estimate a value of the knee joint angle, speed, acceleration, torque, and capacity in the knee joint and are taken from the published works of foreign authors.A trigonometric approximation was used for fitting the experimental data. The resulting dependence of the reduced load on the stock of A is necessary to perform the synthesis of A. The criterion for linear mechanisms mentioned in the D.N. Popov’s work is advisable to use as a possible criterion for optimization of A.The results obtained are as follows:1. Kinematics linkage mechanism is described using relationships for dependencies of its geometrical parameters, namely a cylinder piston stroke x (or ρ and a links angle β.2. Obtained polynomials of kinematic relationships allow a synthesis of

  15. Flexible parallel implicit modelling of coupled thermal-hydraulic-mechanical processes in fractured rocks

    Science.gov (United States)

    Cacace, Mauro; Jacquey, Antoine B.

    2017-09-01

    Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracture-solid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment) which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton-Raphson or by free Jacobian inexact Newton-Krylow schemes) on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres) and temporal scales (from minutes to hundreds of years).

  16. Vacuum-actuated percutaneous insertion/implantation tool for flexible neural probes and interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, Heeral; Bennett, William J.; Pannu, Satinderpall S.; Tooker, Angela C.

    2017-03-07

    A flexible device insertion tool including an elongated stiffener with one or more suction ports, and a vacuum connector for interfacing the stiffener to a vacuum source, for attaching the flexible device such as a flexible neural probe to the stiffener during insertion by a suction force exerted through the suction ports to, and to release the flexible device by removing the suction force.

  17. Graphene-polydimethylsiloxane/chromium bilayer-based flexible, reversible, and large bendable photomechanical actuators

    Science.gov (United States)

    Leeladhar; Raturi, Parul; Kumar, Ajeet; Singh, J. P.

    2017-09-01

    We demonstrate the fabrication of highly versatile photomechanical actuators based on graphene-polymer/metal bilayers that offers fast, low-cost fabrication, large deflection, reversible actuation under zero applied pre-strain, and wavelength-selective response. The photomechanical actuator consists of a graphene nanoplatelet (GNP)-polydimethylsiloxane (PDMS) nanocomposite with a thin chromium metal coating of 35 nm thickness on the backside of the structure. The photomechanical response of the GNP-PDMS/Cr photomechanical actuator was measured by recording the variation of the bending angle upon infrared (IR) light illumination. The bending in the bilayer actuator is caused by the generation of thermal stress due to the large mismatch (the ratio being 1/20) of the thermal expansion coefficient between the two layers as a result of IR absorption by GNPs and a subsequent increase in the local temperature. The maximum bending angle was found to be about 40 degrees with a corresponding large deflection value of about 6-7 mm within 6 s for IR illumination with an intensity of 550 mW cm-2. The corresponding actuation response and relaxation times were about 1 and 3 s, respectively. The GNP-PDMS/Cr bilayer combination when integrated with the standard surface micromachining technique of micro-electromechanical system fabrication can find useful applications in the realization of micro soft-robotics, controlled drug delivery, and light-driven micro switches i.e. micro-optomechanical systems.

  18. Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

    Science.gov (United States)

    Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

  19. Simultaneous Piezoelectric Actuator and Sensor Placement Optimization and Control Design of Manipulators with Flexible Links Using SDRE Method

    Directory of Open Access Journals (Sweden)

    Alexandre Molter

    2010-01-01

    Full Text Available This paper presents a control design for flexible manipulators using piezoelectric actuators bonded on nonprismatic links. The dynamic model of the manipulator is obtained in a closed form through the Lagrange equations. Each link is discretized using finite element modal formulation based on Euler-Bernoulli beam theory. The control uses the motor torques and piezoelectric actuators for controlling vibrations. An optimization problem with genetic algorithm (GA is formulated for the location and size of the piezoelectric actuator and sensor on the links. The natural frequencies and mode shapes are computed by the finite element method, and the irregular beam geometry is approximated by piecewise prismatic elements. The State-Dependent Riccati Equation (SDRE technique is used to derive a suboptimal controller for a robot control problem. A state-dependent equation is solved at each new point obtained for the variables from the problem, along the trajectory to obtain a nonlinear feedback controller. Numerical tests verify the efficiency of the proposed optimization and control design.

  20. Adaptive Robust Sliding Mode Vibration Control of a Flexible Beam Using Piezoceramic Sensor and Actuator: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Ruo Lin Wang

    2014-01-01

    Full Text Available This paper presents an experimental study of an adaptive robust sliding mode control scheme based on the Lyapunov’s direct method for active vibration control of a flexible beam using PZT (lead zirconate titanate sensor and actuator. PZT, a type of piezoceramic material, has the advantages of high reliability, high bandwidth, and solid state actuation and is adopted here in forms of surface-bond patches for vibration control. Two adaptive robust sliding mode controllers for vibration suppression are designed: one uses a discontinuous bang-bang robust compensator and the other uses a smooth compensator with a hyperbolic tangent function. Both controllers guarantee asymptotic stability, as proved by the Lyapunov’s direct method. Experimental results verified the effectiveness and the robustness of both adaptive sliding mode controllers. However, from the experimental results, the bang-bang robust compensator causes small-magnitude chattering because of the discontinuous switching actions. With the smooth compensator, vibration is quickly suppressed and no chattering is induced. Furthermore, the robustness of the controllers is successfully demonstrated with ensured effectiveness in vibration control when masses are added to the flexible beam.

  1. Study on rubber gas actuators driven by the Hydrogen Storage Alloy for in-pipe inspection mobile robots with flexible structure and on an application

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Toshio; Hosokai, Hidemi (Science Univ. of Tokyo (Japan). Faculty of Engineering); Uemura, Masahiro

    1989-06-01

    This paper deals with rubber actuators using Hydrogen Storage Alloy for an in-pipe inspection robot, which has the capability of moving inside pipelines with two inches diameter. Since in-pipe inspection robots require flexible mechanisms for going through complicated construction of pipeline networks, the actuators which are light in weight and flexible must first be developed rather than using conventional actuators. For this purpose, rubber actuators with both stretching and shrinking characteristics are shown here for the application of such a robot. The proposed robot uses these actuators with six degrees of freedom, so that it has more flexibility and adaptability in motion: it can move in the inch worm mode through pipelines and has adaptability to the change of pipe diameters and also of passing over the L-joints and T-joints of pipelines. The method of activating the robot is proposed as the robot dock method, thus the robot actuators can initially be activated by hydrogen gas. The control method is also shown with an example of the T-joint movement. (author).

  2. A Study on Piezoelectric Actuators and Sensors for Vibration Control of Flexible Space Structures

    Science.gov (United States)

    1993-09-23

    design successful stabilizing control laws. Once again, the nearly co-located sensor/actuator system makes it possible to build a stabilizing set of... stabilizing control laws used in this thesis, in combination with optimal performance requirements 36 RBZRBZNCZB 1. Newman, Scott M., Active Damping Control of

  3. Decentralized harmonic active vibration control of a flexible plate using piezoelectric actuator-sensor pairs.

    Science.gov (United States)

    Baudry, Matthieu; Micheau, Philippe; Berry, Alain

    2006-01-01

    We have investigated decentralized active control of periodic panel vibration using multiple pairs combining PZT actuators and PVDF sensors distributed on the panel. By contrast with centralized MIMO controllers used to actively control the vibrations or the sound radiation of extended structures, decentralized control using independent local control loops only requires identification of the diagonal terms in the plant matrix. However, it is difficult to a priori predict the global stability of such decentralized control. In this study, the general situation of noncollocated actuator-sensor pairs was considered. Frequency domain gradient and Newton-Raphson adaptation of decentralized control were analyzed, both in terms of performance and stability conditions. The stability conditions are especially derived in terms of the adaptation coefficient and a control effort weighting coefficient. Simulations and experimental results are presented in the case of a simply supported panel with four PZT-PVDF pairs distributed on it. Decentralized vibration control is shown to be highly dependent on the frequency, but can be as effective as a fully centralized control even when the plant matrix is not diagonal-dominant or is not strictly positive real (not dissipative).

  4. Vibration control of flexible spacecraft actuated by piezoceramics via variable structure strategy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presented a hybrid control scheme to vibration reduction of flexible spacecraft during rotational maneuver by using variable structure output feedback control(VSOFC)and piezoelectric materials. The control configuration included the attitude controller based on VSOFC method and vibration attenuator designed by constant-gain negative velocity feedback control. The attitude controller consisted of a linear feedback term and a discontinuous feedback term. With the presence of this attitude controller, an additional flexible control system acting on the flexible parts can be designed for vibration control. Compared with conventional proportional-derivative(PD)control, the developed control scheme guarantees not only the stability of the closed-loop system, but also yields better performance and robustness in the presence of parametric uncertainties and external disturbance. Simulation results are presented for the spacecraft model to show the effectiveness of the proposed control techniques.

  5. Flexible bacterial cellulose / permalloy nanocomposite xerogel sheets – Size scalable magnetic actuator-cum-electrical conductor

    Directory of Open Access Journals (Sweden)

    V. Thiruvengadam

    2017-03-01

    Full Text Available Permalloy nanoparticles containing bacterial cellulose hydrogel obtained after reduction was compressed into a xerogel flexible sheet by hot pressing at 60 ° C at different pressures. The permalloy nanoparticles with an ordered structure have a bimodal size distribution centered around 25 nm and 190 nm. The smaller nanoparticles are superparamagnetic while the larger particles are ferromagnetic at room temperature. The sheets have a room temperature magnetisation of 20 emug-1 and a coercivity of 32 Oe. The electrical conductivity of the flexible sheets increases with hot pressing pressure from 7 Scm-1 to 40 Scm-1 at room temperature.

  6. On the placement of actuators and sensors for flexible structures with closely spaced modes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

  7. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    Science.gov (United States)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  8. Simultaneous Investigation of Flexibility and Plasma Actuation Effects on the Aerodynamic Characteristics of an Oscillating Airfoil

    OpenAIRE

    Arash Mahboubi Doust; Abas Ramiar; Morteza Dardel

    2016-01-01

    In this work, a numerical study of two dimensional laminar incompressible flow around the flexible oscillating NACA0012 airfoil is performed using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping is considered. Reynolds number for these motions is assumed fixed at 12000. One of the important issues that must be considered in designing air structures, in particular the aircraft wing, is the interaction between the air and the elastic aircraft wings that i...

  9. Modelling and Simulation of Mobile Hydraulic Crane with Telescopic Arm

    DEFF Research Database (Denmark)

    Nielsen, Brian; Pedersen, Henrik Clemmensen; Andersen, Torben Ole

    2005-01-01

    paper a model of a loader crane with a flexible telescopic arm is presented, which may be used for evaluating control strategies. The telescopic arm is operated by four actuators connected hydraulically by a parallel circuit. The operating sequences of the individual actuators is therefore...... not controllable, but depends on the flow from the common control valve, flow resistances between the actuators and friction. The presented model incorporates structural flexibility of the telescopic arm and is capable of describing the dynamic behaviour of both the hydraulic and the mechanical system, including...... the relative movement of the individual mechanical bodies in the telescopic arm. The model is verified through comparisons between simulated and measured results for various operating conditions....

  10. Adaptive fuzzy tracking control for a constrained flexible air-breathing hypersonic vehicle based on actuator compensation

    Directory of Open Access Journals (Sweden)

    Peng Fei Wang

    2016-10-01

    Full Text Available The design of an adaptive fuzzy tracking control for a flexible air-breathing hypersonic vehicle with actuator constraints is discussed. Based on functional decomposition methodology, velocity and altitude controllers are designed. Fuzzy logic systems are applied to approximate the lumped uncertainty of each subsystem of air-breathing hypersonic vehicle model. Every controllers contain only one adaptive parameter that needs to be updated online with a minimal-learning-parameter scheme. The back-stepping design is not demanded by converting the altitude subsystem into the normal output-feedback formulation, which predigests the design of a controller. The special contribution is that novel auxiliary systems are developed to compensate both the tracking errors and desired control laws, based on which the explored controller can still provide effective tracking of velocity and altitude commands when the inputs are saturated. Finally, reference trajectory tracking simulation shows the effectiveness of the proposed method in its application to air-breathing hypersonic vehicle control.

  11. Hydraulic manipulator design, analysis, and control at Oak Ridge National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Kress, R.L.; Jansen, J.F. [Oak Ridge National Lab., TN (United States). Robotics and Process Systems Div.; Love, L.J. [Oak Ridge Inst. for Science and Education, TN (United States); Basher, A.M.H. [South Carolina State Univ., Orangeburg, SC (United States)

    1996-09-01

    To meet the increased payload capacities demanded by present-day tasks, manipulator designers have turned to hydraulics as a means of actuation. Hydraulics have always been the actuator of choice when designing heavy-life construction and mining equipment such as bulldozers, backhoes, and tunneling devices. In order to successfully design, build, and deploy a new hydraulic manipulator (or subsystem) sophisticated modeling, analysis, and control experiments are usually needed. To support the development and deployment of new hydraulic manipulators Oak Ridge National Laboratory (ORNL) has outfitted a significant experimental laboratory and has developed the software capability for research into hydraulic manipulators, hydraulic actuators, hydraulic systems, modeling of hydraulic systems, and hydraulic controls. The hydraulics laboratory at ORNL has three different manipulators. First is a 6-Degree-of-Freedom (6-DoF), multi-planer, teleoperated, flexible controls test bed used for the development of waste tank clean-up manipulator controls, thermal studies, system characterization, and manipulator tracking. Finally, is a human amplifier test bed used for the development of an entire new class of teleoperated systems. To compliment the hardware in the hydraulics laboratory, ORNL has developed a hydraulics simulation capability including a custom package to model the hydraulic systems and manipulators for performance studies and control development. This paper outlines the history of hydraulic manipulator developments at ORNL, describes the hydraulics laboratory, discusses the use of the equipment within the laboratory, and presents some of the initial results from experiments and modeling associated with these hydraulic manipulators. Included are some of the results from the development of the human amplifier/de-amplifier concepts, the characterization of the thermal sensitivity of hydraulic systems, and end-point tracking accuracy studies. Experimental and analytical

  12. Flexible Zinc-Tin Oxide Thin Film Transistors Operating at 1 kV for Integrated Switching of Dielectric Elastomer Actuators Arrays.

    Science.gov (United States)

    Marette, Alexis; Poulin, Alexandre; Besse, Nadine; Rosset, Samuel; Briand, Danick; Shea, Herbert

    2017-08-01

    Flexible high-voltage thin-film transistors (HVTFTs) operating at more than 1 kV are integrated with compliant dielectric elastomer actuators (DEA) to create a flexible array of 16 independent actuators. To allow for high-voltage operation, the HVTFT implements a zinc-tin oxide channel, a thick dielectric stack, and an offset gate. At a source-drain bias of 1 kV, the HVTFT has a 20 µA on-current at a gate voltage bias of 30 V. Their electrical characteristics enable the switching of DEAs which require drive voltages of over 1 kV, making control of an array simpler in comparison to the use of external high-voltage switching. These HVTFTs are integrated in a flexible haptic display consisting of a 4 × 4 matrix of DEAs and HVTFTs. Using a single 1.4 kV supply, each DEA is independently switched by its associated HVTFT, requiring only a 30 V gate voltage for full DEA deflection. The 4 × 4 display operates well even when bent to a 5 mm radius of curvature. By enabling DEA switching at low voltages, flexible metal-oxide HVTFTs enable complex flexible systems with dozens to hundreds of independent DEAs for applications in haptics, Braille displays, and soft robotics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Soft and flexible PEDOT/PSS films for applications to soft actuators

    Science.gov (United States)

    Li, Yuechen; Tanigawa, Ryo; Okuzaki, Hidenori

    2014-07-01

    Stretchable and highly conductive PEDOT/PSS/Xyl films were prepared by casting an aqueous dispersion of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) as colloidal gel particles containing xylitol (Xyl) and subsequent heating. The electrical conductivity of the PEDOT/PSS/Xyl film containing 50 wt% of xylitol significantly increased from 115 S cm-1 to 407 S cm-1 by heating at 140 °C in air for 1 h. It was found that the xylitol had two functions as (i) a plasticizer to weaken hydrogen bonds between PSS of colloidal particles by replacing with that between xylitol and PSS and (ii) the additional capability of increasing the mobility of charge carriers between the colloidal particles. The transparent ionic liquid/polyurethane (IL/PU) gels were fabricated by dissolving thermoplastic polyurethane and ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. By increasing the IL content from 0 wt% to 70 wt%, both ionic conductivity and electric-double-layer capacitance under an electric field increased, while Young’s modulus, strength and elongation at break decreased. The IL/PU/PEDOT/PSS/Xyl composites were fabricated by sandwiching the IL/PU gel between two soft and flexible PEDOT/PSS/Xyl films. Upon application of 2 V, the IL/PU/PEDOT/PSS/Xyl composite (IL = 70%) showed quick and intensive bending toward anode, where the bending displacement at 0.1 Hz attained 2.9 mm, corresponding to the strain of 0.15%, and still worked at frequencies higher than 50 Hz.

  14. Fabrication of a Miniature Paper-Based Electroosmotic Actuator

    Directory of Open Access Journals (Sweden)

    Deepa Sritharan

    2016-11-01

    Full Text Available A voltage-controlled hydraulic actuator is presented that employs electroosmotic fluid flow (EOF in paper microchannels within an elastomeric structure. The microfluidic device was fabricated using a new benchtop lamination process. Flexible embedded electrodes were formed from a conductive carbon-silicone composite. The pores in the layer of paper placed between the electrodes served as the microchannels for EOF, and the pumping fluid was propylene carbonate. A sealed fluid-filled chamber was formed by film-casting silicone to lay an actuating membrane over the pumping liquid. Hydraulic force generated by EOF caused the membrane to bulge by hundreds of micrometers within fractions of a second. Potential applications of these actuators include soft robots and biomedical devices.

  15. A hydrogel actuator with flexible folding deformation and shape programming via using sodium carboxymethyl cellulose and acrylic acid.

    Science.gov (United States)

    Wu, Shuiping; Yu, Feng; Dong, Hua; Cao, Xiaodong

    2017-10-01

    Hydrogel actuator is an intelligent material, which can work as artificial muscle. However, most present hydrogel actuators, due to the inferior mechanical property and uncontrolled folding property, have always resulted in slipping off or the failure of grasping an object with specific shape and required weight. In order to solve this problem, here a tough hydrogel actuator with programmable folding deformation has been prepared by combining the "selective implanting method" and "ionic coordination". The shape and folding angle (from 0 to 180 (o)) of hydrogel actuator can be precisely controlled by altering the location and size of the implanting parts that seems like the joints of finger. The ionic coordination is not only the force to trigger the folding of hydrogel, but also utilized to reinforce the mechanical property. We believed the superior mechanical and shape-programmable property can endow the hydrogel actuator with great application prospect in soft machine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Water Hydraulic Systems

    DEFF Research Database (Denmark)

    Conrad, Finn

    2005-01-01

    The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on......-going research projects on fluid power and mechatronics based on tap water hydraulic servovalves and linear servo actuators and rotary vane actuators for motion control and power transmission. Development and design a novel water hydraulic rotary vane actuator for robot manipulators. Proposed mathematical...... modelling, control and simulation of a water hydraulic rotary vane actuator applied to power and control a two-links manipulator and evaluate performance. The results include engineering design and test of the proposed simulation models compared with IHA Tampere University’s presentation of research...

  17. Integrated high pressure microhydraulic actuation and control for surgical instruments.

    Science.gov (United States)

    Moers, A J M; De Volder, M F L; Reynaerts, D

    2012-08-01

    To reduce the surgical trauma to the patient, minimally invasive surgery is gaining considerable importance since the eighties. More recently, robot assisted minimally invasive surgery was introduced to enhance the surgeon's performance in these procedures. This resulted in an intensive research on the design, fabrication and control of surgical robots over the last decades. A new development in the field of surgical tool manipulators is presented in this article: a flexible manipulator with distributed degrees of freedom powered by microhydraulic actuators. The tool consists of successive flexible segments, each with two bending degrees of freedom. To actuate these compliant segments, dedicated fluidic actuators are incorporated, together with compact hydraulic valves which control the actuator motion. Especially the development of microvalves for this application was challenging, and are the main focus of this paper. The valves distribute the hydraulic power from one common high pressure supply to a series of artificial muscle actuators. Tests show that the angular stroke of the each segment of this medical instrument is 90°.

  18. Flexibility.

    Science.gov (United States)

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  19. Wrist Rehabilitation Device Driven by Pneumatic Flexible Actuator%基于气动柔性驱动器的手腕运动康复装置

    Institute of Scientific and Technical Information of China (English)

    黄磊; 孙中圣; 刘源峰

    2016-01-01

    The several shortcomings exist in the traditional wrist rehabilitation training devices, such as lack of flexibility, complexi structure,high cost and so on. In order to solve the troubles above,this paper designs a wearable wrist rehabilitation device with the flexible pneumatic actuator which can be bended. And it briefly describes the design and manufacturing of this actuator and this de ̄vice. The experiment result shows that the wrist can be driven by the rehabilitation device to do the rehabilitation training very wel,and it is flexible in its movement process.%针对传统的手腕康复训练器存在柔性不足,结构复杂,成本高昂等问题,基于一种可产生弯曲变形的气动柔性驱动器,设计出一种手腕运动康复装置。阐述了气动柔性驱动器和手腕康复装置的设计与制作方法,实验结果表明该手腕康复装置能有效地驱动手腕做运动康复训练,并具有很好的柔性。

  20. Attitude and vibration control of a satellite containing flexible solar arrays by using reaction wheels, and piezoelectric transducers as sensors and actuators

    Science.gov (United States)

    da Fonseca, Ijar M.; Rade, Domingos A.; Goes, Luiz C. S.; de Paula Sales, Thiago

    2017-10-01

    The primary purpose of this paper is to provide insight into control-structure interaction for satellites comprising flexible appendages and internal moving components. The physical model considered herein aiming to attend such purpose is a rigid-flexible satellite consisting of a rigid platform containing two rotating flexible solar panels. The solar panels rotation is assumed to be in a sun-synchronous configuration mode. The panels contain surface-bonded piezoelectric patches that can be used either as sensors for the elastic displacements or as actuators to counteract the vibration motion. It is assumed that in the normal mode operation the satellite platform points towards the Earth while the solar arrays rotate so as to follow the Sun. The vehicle moves in a low Earth polar orbit. The technique used to obtain the mathematical model combines the Lagrangian formulation with the Finite Elements Method used to describe the dynamics of the solar panel. The gravity-gradient torque as well as the torque due to the interaction of the Earth magnetic field and the satellite internal residual magnetic moment is included as environmental perturbations. The actuators are three reaction wheels for attitude control and piezoelectric actuators to control the flexible motion of the solar arrays. Computer simulations are performed using the MATLAB® software package. The following on-orbit satellite operating configurations are object of analysis: i) Satellite pointing towards the Earth (Earth acquisition maneuver) by considering the initial conditions in the elastic displacement equal to zero, aiming the assessment of the flexible modes excitation by the referred maneuver; ii) the satellite pointing towards the Earth with the assumption of an initial condition different from zero for the flexible motion such that the attitude alterations are checked against the elastic motion disturbance; and iii) attitude acquisition accomplished by taking into account initial conditions

  1. High Performance Flexible Actuator of Urchin-Like ZnO Nanostructure/Polyvinylenefluoride Hybrid Thin Film with Graphene Electrodes for Acoustic Generator and Analyzer.

    Science.gov (United States)

    Cheong, Oug Jae; Lee, James S; Kim, Jae Hyun; Jang, Jyongsik

    2016-05-01

    A bass frequency response enhanced flexible polyvinylidene fluoride (PVDF) based thin film acoustic actuator is successfully fabricated. High concentrations of various zinc oxide (ZnO) is embedded in PVDF matrix, enhancing the β phase content and the dielectric property of the composite thin film. ZnO acts as a nucleation agent for the crystallization of PVDF. A chemical vapor deposition grown graphene is used as electrodes, enabling high electron mobility for the distortion free acoustic signals. The frequency response of the fabricated acoustic actuator is studied as a function of the film thickness and filler content. The optimized film has a thickness of 80 μm with 30 wt% filler content and shows 72% and 42% frequency response enhancement in bass and midrange compared to the commercial PVDF, respectively. Also, the total harmonic distortion decreases to 82% and 74% in the bass and midrange regions, respectively. Furthermore, the composite film shows a promising potential for microphone applications. Most of all, it is demonstrated that acoustic actuator performance is strongly influenced by degree of PVDF crystalline.

  2. Demonstration of Vibrational Braille Code Display Using Large Displacement Micro-Electro-Mechanical Systems Actuators

    Science.gov (United States)

    Watanabe, Junpei; Ishikawa, Hiroaki; Arouette, Xavier; Matsumoto, Yasuaki; Miki, Norihisa

    2012-06-01

    In this paper, we present a vibrational Braille code display with large-displacement micro-electro-mechanical systems (MEMS) actuator arrays. Tactile receptors are more sensitive to vibrational stimuli than to static ones. Therefore, when each cell of the Braille code vibrates at optimal frequencies, subjects can recognize the codes more efficiently. We fabricated a vibrational Braille code display that used actuators consisting of piezoelectric actuators and a hydraulic displacement amplification mechanism (HDAM) as cells. The HDAM that encapsulated incompressible liquids in microchambers with two flexible polymer membranes could amplify the displacement of the MEMS actuator. We investigated the voltage required for subjects to recognize Braille codes when each cell, i.e., the large-displacement MEMS actuator, vibrated at various frequencies. Lower voltages were required at vibration frequencies higher than 50 Hz than at vibration frequencies lower than 50 Hz, which verified that the proposed vibrational Braille code display is efficient by successfully exploiting the characteristics of human tactile receptors.

  3. Rotary actuators for plastic valves

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, M. [Georg Fischer Piping Systems Ltd, Schaffhausen (Switzerland)

    2004-07-01

    Flexibility and modularity plus a high level of quality are the defining characteristics of this new generation of actuators from Georg Fischer. In conjunction with the new 546 ball valve, the PA 11/PA 21 pneumatic actuators and the EA 11/EA 21 electric actuators form an optimally co-ordinated system. (orig.)

  4. Positioning magnetorheological actuator

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailov, Valery; Bazinenkov, Alexey; Akimov, Igor [Bauman Moscow State Technical University, 2-nd Baumanskaia st. 5, MT-11, 105005, Moscow (Russian Federation); Borin, Dmitry [Technische Universitaet Dresden, Chair of Magnetofluiddynamics, 01062, Dresden (Germany)], E-mail: mikhailov@bmstu.ru

    2009-02-01

    In this work we consider a construction of a positioning magnetorheological actuator based on bellow units, as well as dynamical model, which include such elements as a magnetically hysteresis, pressure loses in hydraulic system, nonlinearity of rheological behaviour of working fluid. Two operating modes of positioning actuator are taken into account and transients are presented. Dynamical modelling shows possibility for the improvement of a real control system and ensure of submicron precision of positioning with millisecond time of response.

  5. Modeling, fabrication and plasma actuator coupling of flexible pressure sensors for flow separation detection and control in aeronautical applications

    Science.gov (United States)

    Francioso, L.; De Pascali, C.; Pescini, E.; De Giorgi, M. G.; Siciliano, P.

    2016-06-01

    Preventing the flow separation could enhance the performance of propulsion systems and future civil aircraft. To this end, a fast detection of boundary layer separation is mandatory for a sustainable and successful application of active flow control devices, such as plasma actuators. The present work reports on the design, fabrication and functional tests of low-cost capacitive pressure sensors coupled with dielectric barrier discharge (DBD) plasma actuators to detect and then control flow separation. Finite element method (FEM) simulations were used to obtain information on the deflection and the stress distribution in different-shaped floating membranes. The sensor sensitivity as a function of the pressure load was also calculated by experimental tests. The results of the calibration of different capacitive pressure sensors are reported in this work, together with functional tests in a wind tunnel equipped with a curved wall plate on which a DBD plasma actuator was mounted to control the flow separation. The flow behavior was experimentally investigated by particle image velocimetry (PIV) measurements. Statistical and spectral analysis, applied to the output signals of the pressure sensor placed downstream of the profile leading edge, demonstrated that the sensor is able to discriminate different ionic wind velocity and turbulence conditions. The sensor sensitivity in the 0-100 Pa range was experimentally measured and it ranged between 0.0030 and 0.0046 pF Pa-1 for the best devices.

  6. R & D on hydraulic rotary actuator based on virtual prototype technology%虚拟样机技术在摆动液压缸中的应用

    Institute of Scientific and Technical Information of China (English)

    赵先琼; 陈智洪; 刘义伦

    2014-01-01

    虚拟样机技术是一项新兴的产品开发技术,可以有效增强产品品质、缩短产品开发周期、降低产品生产成本。设计好摆动液压缸的虚拟样机,根据摆动液压缸的关键部件“双级渐开线螺旋副”,研究了螺旋角β、输入液压力 P和输出扭矩T 三者之间的关系。通过比对虚拟样机仿真和物理样机实验,得出输入液压力 P和输出扭矩T 为线性正比关系,提高系统液压力 P,相应得到增大的扭矩 T ;通过比较3个螺旋角系列螺旋齿轮组成的渐开线螺旋副输出扭矩 T与导程l之间的关系,在没有齿轮变位的情况下,螺旋齿轮的螺旋角β应尽可能的设计在45°附近,在输入液压力P一定的情况下,优先考虑增大径向尺寸,以增大输出扭矩 T。%Virtual prototype technology is a new method in R&D ,w hich can effectively improve the product quality ,decrease the new product developing time and reduce the production cost .A virtual prototype of rotary actuator is built up for simulation .According to double involute-spiral-pairs ,w hich are the key parts of the hydraulic rotary actuator ,a research is done on the relationship between input pressure and output torque .After simulation and experiment ,it’s found that system pressure and output torque is in a positive linear programming . And another experiment is carried out on the relationship between different helix angles and output torques under same pressure .Through three series simulations within helix angles of 30° ,45° and 60° ,it’s found that we’d better design a helix gear in around 45° helix angle without any gear modification ,so that we can get a optimized output torque .If a bigger output torque is wanted without higher pressure ,the initial way is to increase the gear radial dimension .

  7. Hydraulic Arm Modeling via Matlab SimHydraulics

    OpenAIRE

    Věchet, Stanislav; Krejsa, Jiří

    2009-01-01

    System modeling is a vital tool for cost reduction and design process speed up in most engineering fields. The paper is focused on modeling of hydraulic arm as a part of intelligent prosthesis project, in the form of 2DOF open kinematic chain. The arm model combines mechanical, hydraulic and electric subsystems and uses Matlab as modeling tool. SimMechanics Matlab extension is used for mechanical part modeling, SimHydraulics toolbox is used for modeling of hydraulic circuit used for actuating...

  8. Electrodynamic actuators for rocket engine valves

    Science.gov (United States)

    Fiet, O.; Doshi, D.

    1972-01-01

    Actuators, employed in acoustic loudspeakers, operate liquid rocket engine valves by replacing light paper cones with flexible metal diaphragms. Comparative analysis indicates better response time than solenoid actuators, and improved service life and reliability.

  9. Intelligent Control of a Novel Hydraulic Forging Manipulator

    Directory of Open Access Journals (Sweden)

    J. Wang

    2011-01-01

    Full Text Available The increased demand for large-size forgings has led to developments and innovations of heavy-duty forging manipulators. Besides the huge carrying capacity, some robot features such as force perception, delicacy and flexibility, forging manipulators should also possess. The aim of the work is to develop a heavy-duty forging manipulator with robot features by means of combination of methods in mechanical, hydraulic, and control field. In this paper, through kinematic analysis of a novel forging manipulator, control strategy of the manipulator is proposed considering the function and motion of forging manipulators. Hybrid pressure/position control of hydraulic actuators in forging manipulator is realized. The feasibility of the control method has been verified by the experiments on a real prototype of the novel hydraulic forging manipulator in our institute. The intelligent control of the forging manipulator is performed with programmable logic controller which is suitable for industrial applications.

  10. 无凸轮轴发动机电液驱动配气机构阻尼孔优化设计%Optimization of Orifices on Electro-hydraulic Control Camless Valve Actuator

    Institute of Scientific and Technical Information of China (English)

    谷艳华; 胡乃硕; 高峰军; 李华; 王有坤; 郭英男

    2012-01-01

    The optimized design of orifices in the electro-hydraulic control valve actuator will affect the response and the impact of valve in the camless engine, and thus affect all aspects performance of engine. The mathematical model of the orifices in the valve actuator was designed, and the effects of the orifice ' s diameter to the velocity during opening and landing were analyzed. The model of the camless electro-hydraulic valve actuator was built by using AMESim, the analysis of the influence to the diameter and related position of the valve orifices was done, the results showed that the orifice diameter decreased or the related position of damping chamber orifice increased resulted in the delay of opening time, and the orifice diameter decreased or the related position of main line orifice decreased resulted in the delay of closing time. The parameters of orifices diameter and position were optimized, and the demand of the valve was met by the optimized parameters through the experiments.%无凸轮轴发动机电液驱动配气机构中节流阀阻尼孔的优化设计直接影响气门运动及时响应性能和气门落座冲击性能,进而影响发动机性能.建立了配气机构中节流阀阻尼孔的数学模型,并利用该模型研究了阻尼孔直径对气门开启和落座的影响.使用AMESim搭建了配气机构的仿真模型,研究阻尼孔孔径和相对位置对气门运动的影响.结果表明,阻尼孔直径减小或者阻尼腔阻尼孔相对位置上升会使气门延迟开启;阻尼孔直径减小或者主油路阻尼孔相对位置下降会使气门延迟关闭.优化了阻尼孔孔径和位置参数,试验表明阻尼孔优化设计结果满足发动机对配气机构中气门运动的要求.

  11. 液压驱动仿生多足机器人单腿设计与试验%Design and experiment of single leg of hydraulically actuated bionic multi-legged robot

    Institute of Scientific and Technical Information of China (English)

    陈志伟; 金波; 朱世强; 黄翰林; 陈刚

    2016-01-01

    In order to study the influence of the end-effector’s high speed contact with ground on the robot system when the hydraulically actuated multi-legged robot walks in a dynamic gait and realize its control as well, a single leg prototype of the bio-inspired hydraulically actuated multi-legged robot is developed. The robotic leg's structure is designed on the basis of research and analysis of the skeletons of the large dogs' hind limbs. The hip and knee cylinder layout are designed from the principle of rotating guide bar mechanism and swing guide bar mechanism, respectively. The torque of robotic leg's joint on stance phase is calculated on the basis of former biologists’ research results and the planned joint trajectory of dynamic trotting gait on stance phase. The former biologists have already researched the dynamic gait of large dogs and separately measured the ground reaction forces on individual limb of trotting dogs using a series of four force platforms; the dynamic trotting gait trajectory with a speed of 2.5 m/s is planned as composite cycloid foot trajectory on flight phase with the same body height on stance. And the composite cycloid’s foot trajectory is planned with the specifications: the stride length is 1 m, the stride height is 0.05 m, the period is 4 s, and the duty cycle is 50%. Based on the above bionic design, the mechanical parameters of the robotic single leg are determined: the length of thigh and shank is 0.35 m, the hip joint angle range is [-50°, 70°], the knee joint angle range is [-140°, -20°], the diameter of the cylinder piston is 0.02 m, the diameter of piston rod is 0.01 m, and the stroke length of the piston rod is 0.1 m. The virtual prototype of robotic single leg is designed via the three-dimensional modeling software Solidworks according to the design parameters. Furthermore, the feasibility of the parameters of the designed mechanical structure and hydraulic actuator is verified based on the dynamic vertical hopping

  12. Water Hydraulic Systems

    DEFF Research Database (Denmark)

    Conrad, Finn

    2005-01-01

    The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on-going...

  13. Experimental verification of a large flexible manipulator

    Science.gov (United States)

    Lee, Jac Won; Huggins, James D.; Book, Wayne J.

    1988-01-01

    A large experimental lightweight manipulator would be useful for material handling, for welding, or for ultrasonic inspection of a large structure, such as an airframe. The flexible parallel link mechanism is designed for high rigidity without increasing weight. This constrained system is analyzed by singular value decomposition of the constraint Jacobian matrix. A verification of the modeling using the assumed mode method is presented. Eigenvalues and eigenvectors of the linearized model are compared to the measured system natural frequencies and their associated mode shapes. The modeling results for large motions are compared to the time response data from the experiments. The hydraulic actuator is verified.

  14. Motion Analysis and Control of a Single Leg of Hydraulically Actuated Quadruped Robots during Vertical Hopping%液压驱动四足机器人单腿竖直跳跃运动分析与控制

    Institute of Scientific and Technical Information of China (English)

    张雪峰; 秦现生; 冯华山; 谭小群; 李军; 杨雪宝

    2013-01-01

    针对非结构化环境下四足机器人高速高机动性要求,提出一种液压驱动单腿结构模式.面向竖直跳跃运动,建立液压驱动结构模式下单腿二阶段运动学模型和三阶段动力学模型;进行竖直跳跃运动状态分析、单腿整机质心以1.5 m/s速度瞬时起跳的竖直跳跃运动逆解和仿真;并对竖直跳跃运动过程中地面冲击对机体结构的影响、髋关节和膝关节液压缸动作特性和输出力特性及液压设计等进行讨论.同时,考虑单腿竖直跳跃的周期性,应用液压偏置单腿动力学模型,采用PD迭代学习控制算法进行关节轨迹跟踪控制.仿真结果表明轨迹跟踪迅速收敛且鲁棒性好,为后续样机研究提供设计和控制依据.%To address the requirements of high speed and mobility for quadruped robots under unstructured environments, a structure model of hydraulically actuated single leg is proposed. For vertical hopping, a two-phase kinematic model and a three-phase dynamic model of a single leg are established under the structure model. After that, the state analysis on the vertical hopping is conducted, and the inverse kinematics solution and the simulation of the hopping are also implemented for a single leg mass-center's instant vertical hopping with 1.5 m/s. Then, the ground impact on the body structure, the operation characteristics and the output force of the hip joint and knee joint's hydraulic cylinder, as well as the hydraulic system design during vertical hopping are discussed. Meanwhile, taking the periodicity of vertical hopping of a single leg into consideration, a PD (proportional-derivative) iterative learning control algorithm is applied to joint trajectory tracking, based on single leg's dynamic model with hydraulic offset. The simulation results indicate that rapid and robust convergence is achieved in trajectory tracking using the presented model, which offers the design and control references for the succeeding

  15. Cylindrical Piezoelectric Fiber Composite Actuators

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  16. Design and test of a micro-displacement actuator based on giant magnetostrictive material

    Science.gov (United States)

    Shao, Liang; Yang, Dehua; Yang, Bintang; Chen, Kunxin

    2009-07-01

    To meet the performance requirements of co-focusing and co-phasing of segmented mirror active optics (SMAO) in modern astronomical telescope, micro-displacement actuators with nanometer resolution and millimeter stroke are necessary. The design and test of a micro-displacement actuator based on giant magnetostrictive material is present in this paper. The actuator's main components, such as giant magnetostrictive drive core, displacement pantograph mechanism and output guide mechanism, are discussed in detailed. The giant magnetostrictive drive mechanism generally may offer nanometer resolution and micron stroke. A displacement/stroke pantograph mechanism is designed with absolutely sealed flexible hydraulic structure (ASFHS) to enlarge the stroke. In addition, a secondary giant magnetostrictive drive mechanism is integrated to serve final resolution of final displacement output. In view of flexure exhibiting excellent mechanical properties free of friction, clearance and lubrication, a flexure guide mechanism with the capacity of excellent lateral load is designed to fulfill linear displacement output steadily. The sub-systems like the giant magnetostrictive drive core and displacement pantograph mechanism have been tested before integration of the whole actuator. The final test of the actuator is carried out with dual frequency laser interferometer at lab. Besides, to meet technical requirements of future extremely large telescope, further development issues mainly related to application practice of the actuator is discussed at the end.

  17. Electric Hydrostatic Actuation - modular building blocks for industrial applications

    OpenAIRE

    Helbig, Achim; Boes, Christoph

    2016-01-01

    Electro Hydrostatic Actuators (EHA) are emerging as a viable option for industrial machine builders as the design combines the best of both electro-mechanical and electro-hydraulic technologies. The EHA is a highly integrated, compact alternative to traditional hydraulic solutions. Automation engineers moving toward electro-mechanical actuation in pursuit of energy efficiency and environmental cleanliness, will find an EHA an attractive option for high force density actuators. This paper will...

  18. Neural network-based adaptive optimal control of a robot hydraulic actuator%机器人液压驱动器神经网络自适应最优控制

    Institute of Scientific and Technical Information of China (English)

    孙广彬; 王宏

    2015-01-01

    In order to effectively control the hydraulic nonlinear systems, a radial basis function (RBF) neural network‐based optimal control applied to the robot hydraulic actuator was presented. First, the hydraulic servo system was modeled based on the physics of the plant. Second, the Kalman filter was applied to estimate the internal state of the system with continuously changing magnitude and frequency of input signal. The model parameters were calculated and grouped for RBF neural net‐work training. Third, with the average of each group of parameters as nominal point, the RBF neural network was used to learn the rules how feedback gains changes with system parameters. Finally, the trained neural network was used to predict the feedback gains on line based on the parameter estimate of Kalman Filter and the trained adaptive controller. The proposed controller was validated by experi‐ment with setting time and tracking error to be 1/2 and 1/3 of the conventional linear quadratic requla‐tor controller, respectively.%为了有效地控制液压非线性系统,提出基于RB F神经网络的自适应最优控制系统,应用于机器人液压驱动器。首先,建立了液压系统的动力学模型;然后,输入幅值和频率连续变化的信号,应用卡尔曼滤波器估计液压系统状态,进而计算出模型参数,对模型参数进行分组用于训练RB F神经网络;接着,对不同组参数求平均作为参考点,用RB F神经网络学习最优控制器反馈增益随系统参数的变化规律;最后,训练完成的神经网络根据卡尔曼滤波器参数估计值在线预测并调节控制器增益。经实验验证,该控制系统调节时间和跟踪误差仅为普通线性二次型最优控制器的1/2和1/3左右。

  19. Testing of improved polyimide actuator rod seals at high temperature and under vacuum conditions for use in advanced aircraft hydraulic systems

    Science.gov (United States)

    Sellereite, B. K.; Waterman, A. W.; Nelson, W. G.

    1974-01-01

    Polyimide second-stage rod seals were evaluated to determine their suitability for applications in space station environments. The 6.35-cm (2.5-in.)K-section seal was verified for thermal cycling operation between room temperature and 478 K (400 F) and for operation in a 133 micron PA(0.000001 mm Hg) vacuum environment. The test seal completed the scheduled 96 thermal cycles and 1438 hr in vacuum with external rod seal leakage well within the maximum allowable of two drops per 25 actuation cycles. At program completion, the seals showed no signs of structural degradation. Posttest inspection showed the seals retained a snug fit against the shaft and housing walls, indicating additional wear life capability. Evaluation of a molecular flow section during vacuum testing, to inhibit fluid loss through vaporization, showed it to be beneficial with MIL-H-5606, a petroleum-base fluid, in comparison with MIL-H-83282, a synthetic hydrocarbon-base fluid.

  20. An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology

    OpenAIRE

    Guojun Liu; Yanyan Zhang; Jianfang Liu; Jianqiao Li; Chunxiu Tang; Tengfei Wang; Xuhao Yang

    2016-01-01

    An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT) actuation and electrorheological fluids (ERFs) control technology is presented. The actuator consists of actuation unit (PZT stack pump), fluid control unit (ERFs valve), and execution unit (hydraulic actuator). In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type) of the volume c...

  1. Study on Flexible Cantilever Beam Vibration Control System Based on Piezoelectric Self-sensing Actuator%压电自感知柔性悬臂梁振动控制系统研究

    Institute of Scientific and Technical Information of China (English)

    缑新科; 李大鹏

    2011-01-01

    将压电悬臂梁系统离散化的状态空间方程作为预测模型,设计了预测函数控制器.采用电桥电路法分离出压电自感知执行器的感知信号,经过预测函数控制器处理后输出的控制信号作用于自感知执行器,产生相应的执行力来抑制悬臂梁的振动,从而达到振动控制的目的.仿真结果表明,所设计的振动控制系统对柔性悬臂梁振动抑制是非常有效的.%Regarding the discrete state-space equation as prediction model,the paper designs the predictive functional controller. The sense signal of piezoelectric self-sensing actuator is separated by the bridge circuit. After processing the sense signal with the predictive functional controller, the control signal is outputted to control piezoelectric self-sensing actuator. The stress is produced from the self-sensing actuator to control the flexible cantilever beam vibration. The simulation results show the designed system is very efficient for vibration suppression.

  2. Shape-Memory-Alloy Actuator For Flight Controls

    Science.gov (United States)

    Barret, Chris

    1995-01-01

    Report proposes use of shape-memory-alloy actuators, instead of hydraulic actuators, for aerodynamic flight-control surfaces. Actuator made of shape-memory alloy converts thermal energy into mechanical work by changing shape as it makes transitions between martensitic and austenitic crystalline phase states of alloy. Because both hot exhaust gases and cryogenic propellant liquids available aboard launch rockets, shape-memory-alloy actuators exceptionally suited for use aboard such rockets.

  3. Microprocessor controlled proof-mass actuator

    Science.gov (United States)

    Horner, Garnett C.

    1987-01-01

    The objective of the microprocessor controlled proof-mass actuator is to develop the capability to mount a small programmable device on laboratory models. This capability will allow research in the active control of flexible structures. The approach in developing the actuator will be to mount all components as a single unit. All sensors, electronic and control devices will be mounted with the actuator. The goal for the force output capability of the actuator will be one pound force. The programmable force actuator developed has approximately a one pound force capability over the usable frequency range, which is above 2 Hz.

  4. Closed-Loop Signal Shaping Attitude Maneuvering Control for Flexible Spacecraft Subject to Actuator Saturation%控制受限柔性航天器姿态机动内闭环成形控制

    Institute of Scientific and Technical Information of China (English)

    孔宪仁; 杨正贤; 董晓光; 廖俊

    2011-01-01

    The problem of attitude maneuvering control of flexible spacecraft subject to actuator saturation is dealt with in this paper. To satisfy pointing requirement and simultaneously suppress vibration, a feedhack controller combined with closed-loop signal shaping is designed. The closed-loop aignal shaping partially delayed, is located within the feedback loop to reduce the residual vibration. This type of control architecture can be used advantageously to reject sensor disturbances and discontinuoua nonlinearities such as actuator saturation. Physical experiment results demonstrate that the proposed approach can significantly reduce the vibration of the flexible appendages during the fast angle maneuver subject to actuator saturation; the results also show that the presented control algorithm has the advantages of simplicity and efficiency for practical on-board computer operation.%针对柔性航天器带有执行机构饱和的姿态控制问题,提出了一种将反馈控制与内闭环信号成形相结合的控制方法.将成形器作用于系统内闭环回路中,通过人为引人控制延时达到抑制振动的目的,避免敏感器扰动、执行机构饱和等非线性影响控制器振动抑制效果.全物理实验结果表明,在反作用飞轮存在控制力矩饱和的情况下,该方法不仅使航天器快速地、平稳地完成高精度姿态机动,而且显著地减少了柔性结构的弹性振动,具有算法简单、易于在轨实时计算的优点.

  5. Remotely Adjustable Hydraulic Pump

    Science.gov (United States)

    Kouns, H. H.; Gardner, L. D.

    1987-01-01

    Outlet pressure adjusted to match varying loads. Electrohydraulic servo has positioned sleeve in leftmost position, adjusting outlet pressure to maximum value. Sleeve in equilibrium position, with control land covering control port. For lowest pressure setting, sleeve shifted toward right by increased pressure on sleeve shoulder from servovalve. Pump used in aircraft and robots, where hydraulic actuators repeatedly turned on and off, changing pump load frequently and over wide range.

  6. Integrated hydraulic cooler and return rail in camless cylinder head

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, Craig D [Clawson, MI; Neal, Timothy L [Ortonville, MI; Swain, Jeff L [Flushing, MI; Raimao, Miguel A [Colorado Springs, CO

    2011-12-13

    An engine assembly may include a cylinder head defining an engine coolant reservoir, a pressurized fluid supply, a valve actuation assembly, and a hydraulic fluid reservoir. The valve actuation assembly may be in fluid communication with the pressurized fluid supply and may include a valve member displaceable by a force applied by the pressurized fluid supply. The hydraulic fluid reservoir may be in fluid communication with the valve actuation assembly and in a heat exchange relation to the engine coolant reservoir.

  7. Series Elastic Actuators for legged robots

    Science.gov (United States)

    Pratt, Jerry E.; Krupp, Benjamin T.

    2004-09-01

    Series Elastic Actuators provide many benefits in force control of robots in unconstrained environments. These benefits include high force fidelity, extremely low impedance, low friction, and good force control bandwidth. Series Elastic Actuators employ a novel mechanical design architecture which goes against the common machine design principal of "stiffer is better." A compliant element is placed between the gear train and driven load to intentionally reduce the stiffness of the actuator. A position sensor measures the deflection, and the force output is accurately calculated using Hooke"s Law (F=Kx). A control loop then servos the actuator to the desired output force. The resulting actuator has inherent shock tolerance, high force fidelity and extremely low impedance. These characteristics are desirable in many applications including legged robots, exoskeletons for human performance amplification, robotic arms, haptic interfaces, and adaptive suspensions. We describe several variations of Series Elastic Actuators that have been developed using both electric and hydraulic components.

  8. Dynamic Effects of Embedded Macro-Fiber Composite Actuators on Ultra-Light Flexible Structures of Repeated Pattern- a Homogenization Approach

    Directory of Open Access Journals (Sweden)

    A. Salehian

    2012-01-01

    Full Text Available Motivated by deployable satellite technology, this article presents a homogenization model of an inflatable, rigidized lattice structure with distributed macro-fiber composite (MFC actuation. The model is based upon a general expression for the strain and kinetic energy of a fundamental repeated element of the structure. These expressions are reduced in order and expressed in terms of the strain and displacement components of an equivalent one-dimensional vibration model. The resulting model is used to analyze changes in the structural natural frequencies introduced by the local effects of the added macro-fiber composite actuators for several configurations. A finite element solution is used as a comparison for the homogenization model, and the two are shown to be in good agreement, although the latter requires significantly less computational effort.

  9. NEW PRECISION PIEZOELECTRIC STEP ACTUATOR

    Institute of Scientific and Technical Information of China (English)

    LIU Jianfang; YANG Zhigang; FAN Zunqiang; CHENG Guangming

    2006-01-01

    A new precision piezoelectric actuator is proposed to improve its drive capabilities. The actuator is based on the piezoelectric technology. It adopts the principle of bionics and works with a new method of stator initiative anchoring/loosen and a distortion structure of double-side thin flexible hinge. It solves the problem of anchoring/loosen, frequency, journey, resolution and velocity. The experiment shows that the new linear piezoelectric actuator works with high frequency (100 Hz), high speed (502 μm/s), large travel (>10 mm), high resolution (0.05 μm) and high load (100 N). This kind of new piezoelectric actuator will be applied for large travel and high resolution driving device, optics engineering, precision positioning and some micromanipulation field.

  10. FLUTTER SUPPRESSION USING DISTRIBUTEDPIEZOELECTRIC ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A piezoelectric actuator has the benefits of flexibility of its position, without time lag and wide bandpass characteristics. The early results of the wind tunnel flutter suppression test using the piezoeletric actuator were presented in Ref.[1]. A rigid rectangular wing model is constrained by a plunge spring and a pitch spring, and a pair of piezoelectric actuators is bonded on both sides of the plunge spring so as to carry out the active control. Refs.[2,3] reported two flutter suppression wind tunnel tests where the distributed piezoelectric actuators were used. In Ref.[2] low speed wind tunnel tests were conducted with aluminum and composite plate-like rectangular models fully covered by piezoelectric actuators. Flutter speed is increased by 11%. In Ref.[3] a composite plate-like swept back model with piezoceramic actuators bonded on the inboard surface was tested in a transonic wind tunnel and a 12% increment of flutter dynamic pressure was achieved.  In the present investigation, an aluminum plate-like rectangular model with inboard bonded piezoceramic actuators is adopted. Active flutter suppression control law has been designed. A series of analyses and ground tests and, finally, low-speed wind tunnel tests with the active control system opened and closed are conducted. Reasonable results have been obtained.

  11. Aerodynamic Optimization for Distributed Electro Mechanical Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Traditional hydraulic actuation and control surface layout both limit span wise control of lift distribution, and require large volume within wing cross-section,...

  12. Optimization of Moving Coil Actuators for Digital Displacement Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Bech, Michael Møller; Roemer, Daniel Beck;

    2016-01-01

    This paper focuses on deriving an optimal moving coil actuator design, used as force pro-ducing element in hydraulic on/off valves for Digital Displacement machines. Different moving coil actuator geometry topologies (permanent magnet placement and magnetiza-tion direction) are optimized...... for actuating annular seat valves in a digital displacement machine. The optimization objectives are to the minimize the actuator power, the valve flow losses and the height of the actuator. Evaluation of the objective function involves static finite element simulation and simulation of an entire operation...

  13. 基于螺旋理论的冗余液压驱动四足机器人运动学分析%Kinematic analysis of redundant hydraulic actuated quadruped robot based on screw theory

    Institute of Scientific and Technical Information of China (English)

    庄未; 黄用华

    2011-01-01

    Research on quadruped robot is mostly made based on the same bend directions of four legs. For redundant quadruped robot, its two forelegs and rear legs become symmetry flections in steady poses. For studying a leg motion and the body motion of hydraulic actuated redundant quadruped robot, kinematic model of quadruped robot was established based on screw theory in this paper, which includes inverse kinematics solution of a single leg and forward solution of the parallel body. Then, the angle ranges of coax joints and knee joints of two rear legs were designed according to the walking plan of robot. Furthermore, the joint variables of two forelegs and the poses of the body were obtained by the mathematical model. Finally, the body posture in a walking plan was compared by MATLAB calculation and ADAMS simulation, and the kinematics model was validated.%四足机器人的各种研究大多基于四条腿弯曲方向一致展开的.对于液压驱动且具有冗余度的四足机器人,静止姿态下,其前面两条腿与后面两条腿成对称弯曲状.为了研究这种机器人单腿运动和躯体运动状态,文中建立了基于螺旋理论的液压驱动四足机器人运动学模型,包括给出了单腿串联运动学逆解和躯体并联运动学正解.然后根据机器人行走过程设计出后面两条腿的髋关节与膝关节摆幅角度,通过建立的运动学模型,得到前面两条腿的关节变量及躯体姿态.最后通过MATLAB数值仿真和ADAMS虚拟样机实验,对机器人在一种行走方案下的躯体运动姿态进行仿真对比,验证了所建运动学模型的可靠性.

  14. Low-power microfluidic electro-hydraulic pump (EHP).

    Science.gov (United States)

    Lui, Clarissa; Stelick, Scott; Cady, Nathaniel; Batt, Carl

    2010-01-07

    Low-power electrolysis-based microfluidic pumps utilizing the principle of hydraulics, integrated with microfluidic channels in polydimethylsiloxane (PDMS) substrates, are presented. The electro-hydraulic pumps (EHPs), consisting of electrolytic, hydraulic and fluidic chambers, were investigated using two types of electrodes: stainless steel for larger volumes and annealed gold electrodes for smaller-scale devices. Using a hydraulic fluid chamber and a thin flexible PDMS membrane, this novel prototype successfully separates the reagent fluid from the electrolytic fluid, which is particularly important for biological and chemical applications. The hydraulic advantage of the EHP device arises from the precise control of flow rate by changing the electrolytic pressure generated, independent of the volume of the reagent chamber, mimicking the function of a hydraulic press. Since the reservoirs are pre-filled with reagents and sealed prior to testing, external fluid coupling is minimized. The stainless steel electrode EHPs were manufactured with varying chamber volume ratios (1 : 1 to 1 : 3) as a proof-of-concept, and exhibited flow rates of 1.25 to 30 microl/min with electrolysis-based actuation at 2.5 to 10 V(DC). The miniaturized gold electrode EHPs were manufactured with 3 mm diameters and 1 : 1 chamber volume ratios, and produced flow rates of 1.24 to 7.00 microl/min at 2.5 to 10 V(AC), with a higher maximum sustained pressure of 343 KPa, suggesting greater device robustness using methods compatible with microfabrication. The proposed technology is low-cost, low-power and disposable, with a high level of reproducibility, allowing for ease of fabrication and integration into existing microfluidic lab-on-a-chip and analysis systems.

  15. A system look at electromechanical actuation for primary flight control

    NARCIS (Netherlands)

    Lomonova, E.A.

    1997-01-01

    An overview is presented of the emergence of the ALL Electric flight control system (FCS) or power-by-wire (PBW) concept. The concept of fly-by-power refers to the actuator using electrical rather than hydraulic power. The development of the primary flight control Electromechanical Actuators (EMAs)

  16. A system look at electromechanical actuation for primary flight control

    NARCIS (Netherlands)

    Lomonova, E.A.

    1997-01-01

    An overview is presented of the emergence of the ALL Electric flight control system (FCS) or power-by-wire (PBW) concept. The concept of fly-by-power refers to the actuator using electrical rather than hydraulic power. The development of the primary flight control Electromechanical Actuators (EMAs)

  17. Study on Characteristics of Hydraulic Servo System for Force Control of Hydraulic Robots

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo-gon; Han, Changsoo [Hanyang University, Seoul (Korea, Republic of); Lee, Jong-won [Korea University of Science and Technology, Seoul (Korea, Republic of); Park, Sangdeok [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)

    2015-02-15

    Because a hydraulic actuator has high power and force densities, this allows the weight of the robot's limbs to be reduced. This allows for good dynamic characteristics and high energy efficiency. Thus, hydraulic actuators are used in some exoskeleton robots and quadrupedal robots that require high torque. Force control is useful for robot compliance with a user or environment. However, force control of a hydraulic robot is difficult because a hydraulic servo system is highly nonlinear from a control perspective. In this study, a nonlinear model was used to develop a simulation program for a hydraulic servo system consisting of a servo valve, transmission lines, and a cylinder. The problems and considerations with regard to the force control performance for a hydraulic servo system were investigated. A force control method using the nonlinear model was proposed, and its effect was evaluated with the simulation program.

  18. Fast-acting valve actuator

    Science.gov (United States)

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  19. Grinding efficiency improvement of hydraulic cylinders parts for mining equipment

    National Research Council Canada - National Science Library

    Aleksandr Korotkov; Vitaliy Korotkov; Leonid Mametyev; Lidia Korotkova; Tatiana Terjaeva

    2017-01-01

    The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms...

  20. Characterization and Testing of an Electrorheological Fluid Valve for Control of ERF Actuators

    OpenAIRE

    Quang-Anh Nguyen; Steven Jens Jorgensen; Joseph Ho; Luis Sentis

    2015-01-01

    Previous studies of electrorheological fluids (ERFs) were motivated by brake, clutch, damping, haptic and resistive applications, but never motivated towards developing an ERF based-hydraulic rotary actuator. One design to make such an actuator is to use ERF-based valves. To fully understand the performance of such an actuator, it is imperative to study ERF valves. For this reason, this paper presents a summary of design considerations for creating ERF-based actuators, an ERF-based valve desi...

  1. Light Actuation of Liquid in Optofluidics

    Institute of Scientific and Technical Information of China (English)

    WAN Jing; LIANG Zhong-cheng

    2008-01-01

    Optofluidics is the integration of optics and microfluidics(so-called lab on the chip). Wherein the actuation of liquid is a key technic. In a variety of methods for controlling microscale liquid, the light actuation is particularly interesting. The light actuation offers a novel way to control the flow of fluids for biomedical and biotechnological applications, etc.. The complexity and cost of devices sometimes may be greatly reduced by using complete optical control and may be more flexible in operation than other methods. However the light actuation of liquid is a burgeoning field as well as optofluidics. There is lots of work to do. Here we systematically describe four mechanisms for the light actuation of liquid based on the following points: optoelectrowetting, photothermal effect, radiation pressure, photosensitive substance.

  2. Hydraulic structures

    CERN Document Server

    Chen, Sheng-Hong

    2015-01-01

    This book discusses in detail the planning, design, construction and management of hydraulic structures, covering dams, spillways, tunnels, cut slopes, sluices, water intake and measuring works, ship locks and lifts, as well as fish ways. Particular attention is paid to considerations concerning the environment, hydrology, geology and materials etc. in the planning and design of hydraulic projects. It also considers the type selection, profile configuration, stress/stability calibration and engineering countermeasures, flood releasing arrangements and scouring protection, operation and maintenance etc. for a variety of specific hydraulic structures. The book is primarily intended for engineers, undergraduate and graduate students in the field of civil and hydraulic engineering who are faced with the challenges of extending our understanding of hydraulic structures ranging from traditional to groundbreaking, as well as designing, constructing and managing safe, durable hydraulic structures that are economical ...

  3. Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator

    Science.gov (United States)

    Lin, F. N.; Moore, W. I.; Lundy, F. E.

    1981-01-01

    Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.

  4. HYDRAULIC SERVO

    Science.gov (United States)

    Wiegand, D.E.

    1962-05-01

    A hydraulic servo is designed in which a small pressure difference produced at two orifices by an electrically operated flapper arm in a constantly flowing hydraulic loop is hydraulically amplified by two constant flow pumps, two additional orifices, and three unconnected ball pistons. Two of the pistons are of one size and operate against the additional orifices, and the third piston is of a different size and operates between and against the first two pistons. (AEC)

  5. Elastomeric actuator devices for magnetic resonance imaging

    Science.gov (United States)

    Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

    2008-01-01

    The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

  6. FEEDBACK LINEARISATION APPLIED ON A HYDRAULIC

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Hansen, Michael Rygaard; Pedersen, Henrik C.;

    2005-01-01

    Generally most hydraulic systems are intrensically non-linear, why applying linear control techniques typically results in conservatively dimensioned controllers to obtain stable performance. Non-linear control techniques have the potential of overcoming these problems, and in this paper the focus...... is on developing and applying several different feedback linearisation (FL) controllers to the individual servo actuators in a hydraulically driven servo robot to evaluate and compare their possiblities and limitations. This is done based on both simulation and experimental results....

  7. A solenoid-based active hydraulic engine mount: modelling, analysis, and verification

    OpenAIRE

    Hosseini, Ali

    2010-01-01

    The focus of this thesis is on the design, modelling, identification, simulation, and experimental verification of a low-cost solenoid-based active hydraulic engine mount. To build an active engine mount, a commercial On-Off solenoid is modified to be used as an actuator and it is embedded inside a hydraulic engine mount. The hydraulic engine mount is modelled and tested, solenoid actuator is modelled and identified, and finally the models were integrated to obtain the analytical model of the...

  8. Intelligent controller of a flexible hybrid robot machine for ITER assembly and maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Al-saedi, Mazin I., E-mail: mazin.al-saedi@lut.fi; Wu, Huapeng; Handroos, Heikki

    2014-10-15

    Highlights: • Studying flexible multibody dynamic of hybrid parallel robot. • Investigating fuzzy-PD controller to control a hybrid flexible hydraulically driven robot. • Investigating ANFIS-PD controller to control a hybrid flexible robot. Compare to traditional PID this method gives better performance. • Using the equilibrium of reaction forces between the parallel and serial parts of hybrid robot to control the serial part hydraulically driven. - Abstract: The assembly and maintenance of International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is highly challenging since the tasks performed by the robot involve welding, material handling, and machine cutting from inside the VV. To fulfill the tasks in ITER application, this paper presents a hybrid redundant manipulator with four DOFs provided by serial kinematic axes and six DOFs by parallel mechanism. Thus, in machining, to achieve greater end-effector trajectory tracking accuracy for surface quality, a robust control of the actuators for the flexible link has to be deduced. In this paper, the intelligent control of a hydraulically driven parallel robot part based on the dynamic model and two control schemes have been investigated: (1) fuzzy-PID self tuning controller composed of the conventional PID control and with fuzzy logic; (2) adaptive neuro-fuzzy inference system-PID (ANFIS-PID) self tuning of the gains of the PID controller, which are implemented independently to control each hydraulic cylinder of the parallel robot based on rod position predictions. The obtained results of the fuzzy-PID and ANFIS-PID self tuning controller can reduce more tracking errors than the conventional PID controller. Subsequently, the serial component of the hybrid robot can be analyzed using the equilibrium of reaction forces at the universal joint connections of the hexa-element. To achieve precise positional control of the end effector for maximum precision machining, the hydraulic cylinder should

  9. Basic hydraulics

    CERN Document Server

    Smith, P D

    1982-01-01

    BASIC Hydraulics aims to help students both to become proficient in the BASIC programming language by actually using the language in an important field of engineering and to use computing as a means of mastering the subject of hydraulics. The book begins with a summary of the technique of computing in BASIC together with comments and listing of the main commands and statements. Subsequent chapters introduce the fundamental concepts and appropriate governing equations. Topics covered include principles of fluid mechanics; flow in pipes, pipe networks and open channels; hydraulic machinery;

  10. SMA actuators for morphing wings

    Science.gov (United States)

    Brailovski, V.; Terriault, P.; Georges, T.; Coutu, D.

    An experimental morphing laminar wing was developed to prove the feasibility of aircraft fuel consumption reduction through enhancement of the laminar flow regime over the wing extrados. The morphing wing prototype designed for subsonic cruise flight conditions (Mach 0.2 … 0.3; angle of attack - 1 … +2∘), combines three principal subsystems: (1) flexible extrados, (2) rigid intrados and (3) an actuator group located inside the wing box. The morphing capability of the wing relies on controlled deformation of the wing extrados under the action of shape memory alloys (SMA) actuators. A coupled fluid-structure model of the morphing wing was used to evaluate its mechanical and aerodynamic performances in different flight conditions. A 0.5 m chord and 1 m span prototype of the morphing wing was tested in a subsonic wind tunnel. In this work, SMA actuators for morphing wings were modeled using a coupled thermo-mechanical finite element model and they were windtunnel validated. If the thermo-mechanical model of SMA actuators presented in this work is coupled with the previously developed structureaerodynamic model of the morphing wing, it could serve for the optimization of the entire morphing wing system.

  11. Pressure control valve using proportional electro-magnetic solenoid actuator

    Energy Technology Data Exchange (ETDEWEB)

    Yun, So Nam; Ham, Young Bog; Park, Pyoung Won [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2006-10-15

    This paper presents an experimental characteristics of electro-hydraulic proportional pressure control valve. In this study, poppet and valve body which are assembled into the proportional solenoid were designed and manufactured. The constant force characteristics of proportional solenoid actuator in the control region should be independent of the plunger position in order to be used to control the valve position in the fluid flow control system. The stroke-force characteristics of the proportional solenoid actuator is determined by the shape (or parameters) of the control cone. In this paper, steady state and transient characteristics of the solenoid actuator for electro-hydraulic proportional valve are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attraction force in the control region independently on the stroke position. The effects of the parameters such as control cone length, thickness and taper length are also discussed.

  12. Hydraulic Structures

    Data.gov (United States)

    Department of Homeland Security — This table is required whenever hydraulic structures are shown in the flood profile. It is also required if levees are shown on the FIRM, channels containing the...

  13. Closed Loop Controlled ER-Actuator

    Science.gov (United States)

    Wolff, C.

    The results of the investigation regarding the suitability of ERF when applied in hydraulics have shown so far that constructing electrorheological flow resistors for the control of pressure and volume flow is possible in principle. One of the main advantages when using the ER-technology in hydraulic systems can be seen in the high reaction rate of the ER-effect. The investigations presented in this article document the dynamic qualities of ER-fluids by means of a practical exploitation for the control of a cylinder actuator. Due to the particular possibilities for design of ER-control resistors a compact cylinder has resulted which differs considerably from traditional cylinder actuators in its construction and dynamic behaviour.

  14. Mechatronic Hydraulic Drive with Regulator, Based on Artificial Neural Network

    Science.gov (United States)

    Burennikov, Y.; Kozlov, L.; Pyliavets, V.; Piontkevych, O.

    2017-06-01

    Mechatronic hydraulic drives, based on variable pump, proportional hydraulics and controllers find wide application in technological machines and testing equipment. Mechatronic hydraulic drives provide necessary parameters of actuating elements motion with the possibility of their correction in case of external loads change. This enables to improve the quality of working operations, increase the capacity of machines. The scheme of mechatronic hydraulic drive, based on the pump, hydraulic cylinder, proportional valve with electrohydraulic control and programmable controller is suggested. Algorithm for the control of mechatronic hydraulic drive to provide necessary pressure change law in hydraulic cylinder is developed. For the realization of control algorithm in the controller artificial neural networks are used. Mathematical model of mechatronic hydraulic drive, enabling to create the training base for adjustment of artificial neural networks of the regulator is developed.

  15. Balanced Placement Of Vibration Sensors And Actuators

    Science.gov (United States)

    Gawronski, Wodek

    1996-01-01

    Mathematical approach that involves Hankel singular values leads to method for estimation of optimal placement of relatively few vibration sensors and actuators in multivariable flexible structure. Approach extends and complements previous developments regarding approximate decomposition, to Hankel singular values, of singular values of controllability and observability grammian matrices of multivariable flexible structure. Mathematical constructs also described in "Designing An Approximately Balanced LQG Compensator" (NPO-19000).

  16. Sensors and actuators inherent in biological species

    Science.gov (United States)

    Taya, Minoru; Stahlberg, Rainer; Li, Fanghong; Zhao, Ying Joyce

    2007-04-01

    This paper addresses examples of sensing and active mechanisms inherent in some biological species where both plants and animals cases are discussed: mechanosensors and actuators in Venus Fly Trap and cucumber tendrils, chemosensors in insects, two cases of interactions between different kingdoms, (i) cotton plant smart defense system and (ii) bird-of-paradise flower and hamming bird interaction. All these cases lead us to recognize how energy-efficient and flexible the biological sensors and actuators are. This review reveals the importance of integration of sensing and actuation functions into an autonomous system if we make biomimetic design of a set of new autonomous systems which can sense and actuate under a number of different stimuli and threats.

  17. Novel precision piezoelectric step rotary actuator

    Institute of Scientific and Technical Information of China (English)

    LIU Jianfang; YANG Zhigang; ZHAO Hongwei; CHENG Guangming

    2007-01-01

    A novel piezoelectric (PZT) precision step rotary actuator was developed on the basis of PZT technology.It adopts the principle of bionics and works with an inside anchoring/loosening of the stator and a distortion structure of the uniformly distributed thin flexible hinge to solve problems such as ineffective anchoring/loosening,low step rotary frequency,small travel,poor resolution,low speed and unsteady output.The developed actuator is characterized by high frequency (30 Hz),high speed (380 μrad/s),large travel (>270°),high resolution (1 μrad/step),and work stability.It greatly improves the ability to drive the existing PZT step rotary actuator.The new actuator can be applied in the field of micromanipulation and precision engineering,including precision driving and positioning and optics engineering.

  18. Active Damping Using Distributed Anisotropic Actuators

    Science.gov (United States)

    Schiller, Noah H.; Cabell, Randolph H.; Quinones, Juan D.; Wier, Nathan C.

    2010-01-01

    A helicopter structure experiences substantial high-frequency mechanical excitation from powertrain components such as gearboxes and drive shafts. The resulting structure-borne vibration excites the windows which then radiate sound into the passenger cabin. In many cases the radiated sound power can be reduced by adding damping. This can be accomplished using passive or active approaches. Passive treatments such as constrained layer damping tend to reduce window transparency. Therefore this paper focuses on an active approach utilizing compact decentralized control units distributed around the perimeter of the window. Each control unit consists of a triangularly shaped piezoelectric actuator, a miniature accelerometer, and analog electronics. Earlier work has shown that this type of system can increase damping up to approximately 1 kHz. However at higher frequencies the mismatch between the distributed actuator and the point sensor caused control spillover. This paper describes new anisotropic actuators that can be used to improve the bandwidth of the control system. The anisotropic actuators are composed of piezoelectric material sandwiched between interdigitated electrodes, which enables the application of the electric field in a preferred in-plane direction. When shaped correctly the anisotropic actuators outperform traditional isotropic actuators by reducing the mismatch between the distributed actuator and point sensor at high frequencies. Testing performed on a Plexiglas panel, representative of a helicopter window, shows that the control units can increase damping at low frequencies. However high frequency performance was still limited due to the flexible boundary conditions present on the test structure.

  19. Electro Hydraulic Hitch Control

    DEFF Research Database (Denmark)

    Hansen, M. R.; Andersen, T. O.; Nielsen, B.

    2003-01-01

    system for agricultural applications and driving for transportation. During tranport phases, the lack of suspension causes the vehicle to bounce and pitch, and makes it difficalt to control. Many systems have been proposed to cope with the oscillatory behavior, and different solutions exist. Common......This paper present and discusses R&D results on electro hydraulic hitch control for off-road vehicle, in particular active damping of oscillation occuring on tractors. The research deals with analysis and control of the oscillations occuring on tractors which are design without any susspection...... for most of the systems are that they operate on the hydrailc actuators generally providing the motive forces for moving the implement and/or attachment, typically a plough. The basic idea and physical working principle are to use the implement, moveable relative to the vehicle, as a damper mass. The paper...

  20. Biomimetic actuator and sensor for robot hand

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Baekchul; Chung, Jinah; Cho, Hanjoung; Shin, Seunghoon; Lee, Hyoungsuk; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Jachoon [Sungkyunkwan Univ., Seoul (Korea, Republic of)

    2012-12-15

    To manufacture a robot hand that essentially mimics the functions of a human hand, it is necessary to develop flexible actuators and sensors. In this study, we propose the design, manufacture, and performance verification of flexible actuators and sensors based on Electro Active Polymer (EAP). EAP is fabricated as a type of film, and it moves with changes in the voltage because of contraction and expansion in the polymer film. Furthermore, if a force is applied to an EAP film, its thickness and effective area change, and therefore, the capacitance also changes. By using this mechanism, we produce capacitive actuators and sensors. In this study, we propose an EAP based capacitive sensor and evaluate its use as a robot hand sensor.

  1. Bio-Inspired Flexible Cellular Actuating Systems

    Science.gov (United States)

    2013-11-21

    Volterra transform v(t, y) = w(t, y)− ∫ y L k(y, x)w(t, x)dx (12) and the v-dynamics vtt −bvtyy − avyy = Mv − bpvt − apv, v(t, L) = 0, p > 0. (13) Note...L− y)2 − (L− x)2))√ p((L− y)2 − (L− x)2) . (17) Proof: We can derive expressions for vtt and vyy from (12) vtt = wtt − ∫ y L k(y, x)wtt (x)dx = bwty y

  2. Control of an electro-hydrostatic actuation system for the nose landing gear of an "all electric aircraft"

    OpenAIRE

    Greissner, Carsten; Carl, Udo

    2004-01-01

    The EU research Project Power Optimised Aircraft (POA) investigates the approach to replace primary hydraulic supply by extended electric power systems towards a More or All Electric Aircraft. This contribution presents an electrically powered actuation system for nose landing gears using an EHA (electrohydrostatic actuator) approach. One motor pump unit supplies door and gear actuation as well as the steering system. Different control strategies for the individual actuators are introduced. T...

  3. Application of Advanced Electromagnetic Arrays to High Efficiency, High Bandwidth, Redundant Linear Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There is a need to develop electromechanical actuators to improve performance beyond that of hydraulic devices currently being used in numerous aerospace and...

  4. Worthy test programmes and developments of smart electromechanical actuators

    Science.gov (United States)

    Annaz, Fawaz Yahya

    2007-02-01

    Early aircraft flight control systems were totally manually operated, that is, the force required to move flight control surfaces was generated by the pilot and transmitted by cables and rods. As aerodynamics and airframe technology developed and speeds increased, the forces required to move control surfaces increased, as did the number of surfaces. In order to provide the extra power required, hydraulic technology was introduced. To date, the common element in the development of flight control systems has been, mainly, restricted to this type of technology. This is because of its proven reliability and the lack of alternative technologies. However, the technology to build electromechanically actuated primary flight control systems is now available. Motors developing the required power at the required frequencies are now possible (with the use of high energy permanent magnetic materials and compact high speed electronic circuits). It is this particular development which may make the concept of an 'all electric aircraft' realizable in the near future. The purpose of the all electric aircraft concept is the consolidation of all secondary power systems into electric power. The elimination of hydraulic and pneumatic secondary power systems will improve maintainability, flight readiness and use of energy. This paper will present the development of multi-lane smart electric actuators and offer an insight into other subsequent fields of study. The key areas of study may be categorized as follows. State of the art hydraulic actuators. Electromechanical actuator system test programmes. Development of electromechanical actuators. Modelling of electromechanical actuators.

  5. Photostrictive actuators for photonic control of shallow spherical shells

    Science.gov (United States)

    Shih, Hui-Ru; Tzou, Horn-Sen

    2007-10-01

    Photostrictive materials, exhibiting light-induced strain, are of interest for the future generation of wireless remote control photo-actuators. Photostrictive actuators are expected to be used as the driving component in optically controlled flexible structures. In this paper, the photonic control of flexible spherical shells using discrete photostrictive actuators is investigated. This paper presents a coupled opto-piezothermoelastic shell theory that incorporates photovoltaic, pyroelectric and piezoelectric effects, and has the capability to predict the response of a spherical shell driven by the photostrictive actuators. In this study, the effects of actuator location as well as membrane and bending components on the control action have been analyzed. The results obtained indicate that the control forces are mode and location dependent. Analysis also shows that the membrane control action is much more significant than the bending control action.

  6. Improvement of energy storage motor control circuit of hydraulic actuator in high-voltage circuit breakers%高压断路器液压操动机构储能电机控制回路改进

    Institute of Scientific and Technical Information of China (English)

    张全民; 赵玉柱

    2011-01-01

    高压断路器液压操动机构的常见故障是储能电机频繁启动。通过合理地设计储能电机的控制回路,减少了液压机构频繁启动的现象。%The fault of the mechanism of High voltage circuit-breaker is motor of storaging power high frequency starup.That rationally design control circuit of hydraulic mechanism reduce the fault that motor of storaging power high frequency starup.

  7. Electromagnetic rotational actuation.

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  8. Model of magnetostrictive actuator

    Institute of Scientific and Technical Information of China (English)

    LI Lin; ZHANG Yuan-yuan

    2005-01-01

    The hysteresis of the magnetostrictive actuator was studied. A mathematical model of the hysteresis loop was obtained on the basis of experiment. This model depends on the frequency and the amplitude of the alternating current inputted to the magnetostrictive actuator. Based on the model, the effect of hysteresis on dynamic output of the magnetostrictive actuator was investigated. Then how to consider hysteresis and establish a dynamic model of a magnetostrictive actuator system is discussed when a practical system was designed and applied.

  9. Extended DNA Tile Actuators

    DEFF Research Database (Denmark)

    Kristiansen, Martin; Kryger, Mille; Zhang, Zhao

    2012-01-01

    A dynamic linear DNA tile actuator is expanded to three new structures of higher complexity. The original DNA actuator was constructed from a central roller strand which hybridizes with two piston strands by forming two half-crossover junctions. A linear expansion of the actuator is obtained...

  10. Nonlinear, Adaptive and Fault-tolerant Control for Electro-hydraulic Servo Systems

    DEFF Research Database (Denmark)

    Choux, Martin

    Fluid power systems have been in use since 1795 with the rst hydraulic press patented by Joseph Bramah and today form the basis of many industries. Electro hydraulic servo systems are uid power systems controlled in closed-loop. They transform reference input signals into a set of movements...... in hydraulic actuators (cylinders or motors) by the means of hydraulic uid under pressure. With the development of computing power and control techniques during the last few decades, they are used increasingly in many industrial elds which require high actuation forces within limited space. However, despite...... numerous attractive properties, hydraulic systems are always subject to potential leakages in their components, friction variation in their hydraulic actuators and deciency in their sensors. These violations of normal behaviour reduce the system performances and can lead to system failure...

  11. Effective Actuation: High Bandwidth Actuators and Actuator Scaling Laws

    Science.gov (United States)

    2007-11-02

    piezo elements mounted on structural members and devices that exhibited aeroacoustic resonance. The former type of actuator ( piezo ) was considered...Raman and Kibens (Raman et al. 2000). These experiments involved high-frequency forcing applied to low-speed flows using wedge piezo actuators and... Subharmonic Interaction and Wall Influence," AIAA- 86-1047, May, 1986. Davis, S. A., 2000, "The manipulation of large and small flow structures in single and

  12. Power analysis in flexible automation

    Science.gov (United States)

    Titus, Nathan A.

    1992-12-01

    The performance of an automation or robotic device can be measured in terms of its power efficiency. Screw theory is used to mathematically define the task instantaneously with two screws. The task wrench defines the effect of the device on its environment, and the task twist describes the motion of the device. The tasks can be separated into three task types: kinetic, manipulative, and reactive. Efficiency metrics are developed for each task type. The output power is strictly a function of the task screws, while device input power is shown to be a function of the task, the device Jacobian, and the actuator type. Expressions for input power are developed for two common types of actuators, DC servometers and hydraulic actuators. Simple examples are used to illustrate how power analysis can be used for task/workspace planning, actuator selection, device configuration design, and redundancy resolution.

  13. Compact Active Vibration Control System for a Flexible Panel

    Science.gov (United States)

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

    2014-01-01

    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.

  14. A magnetorheological actuation system: test and model

    Science.gov (United States)

    John, Shaju; Chaudhuri, Anirban; Wereley, Norman M.

    2008-04-01

    Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data.

  15. Disposable Fluidic Actuators for Miniature In-Vivo Surgical Robotics.

    Science.gov (United States)

    Pourghodrat, Abolfazl; Nelson, Carl A

    2017-03-01

    Fusion of robotics and minimally invasive surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems to miniature in-vivo robotics. However, with miniaturization of electric-motor-driven surgical robots, there comes a trade-off between the size of the robot and its capability. Slow actuation, low load capacity, sterilization difficulties, leaking electricity and transferring produced heat to tissues, and high cost are among the key limitations of the use of electric motors in in-vivo applications. Fluid power in the form of hydraulics or pneumatics has a long history in driving many industrial devices and could be exploited to circumvent these limitations. High power density and good compatibility with the in-vivo environment are the key advantages of fluid power over electric motors when it comes to in-vivo applications. However, fabrication of hydraulic/pneumatic actuators within the desired size and pressure range required for in-vivo surgical robotic applications poses new challenges. Sealing these types of miniature actuators at operating pressures requires obtaining very fine surface finishes which is difficult and costly. The research described here presents design, fabrication, and testing of a hydraulic/pneumatic double-acting cylinder, a limited-motion vane motor, and a balloon-actuated laparoscopic grasper. These actuators are small, seal-less, easy to fabricate, disposable, and inexpensive, thus ideal for single-use in-vivo applications. To demonstrate the ability of these actuators to drive robotic joints, they were modified and integrated in a robotic arm. The design and testing of this surgical robotic arm are presented to validate the concept of fluid-power actuators for in-vivo applications.

  16. Point-actuated aperture antenna development

    Science.gov (United States)

    Angelino, Marc; Washington, Gregory N.

    2001-08-01

    Consistent changes in both commercial and military satellite needs have created the need for antennas with additional flexibility. Military surveillance may require the ability to focus the radiation pattern to increase the bandwidth or resolution in a certain area. Commercial satellites may need to change coverage area to meet evolving consumer needs or to compensate for adverse weather or atmospheric conditions. Recent studies on active antennas have shown that the far field radiation pattern can be changed by altering the shape of the sub reflector. In this research, we control the antenna far field radiation pattern by controlling the shape of the sub reflector using numerous point actuators placed perpendicular to the reflector surface. The PZT stack coupled with a stick-slip mechanism give the point actuators used in this design an advantage over similar studies using PZT bimorph or PVDF actuators to generate the actuation force in that the displacement can be maintained without the continuous application of voltage. An electromechanical model is used to describe the motion of the stack, and the stick slip mechanism is modeled similar to power screw-type actuators. A combined finite element/electromagnetic analysis code is used to determine the desired shape of the reflector, and the corresponding actuator displacements. The final shape of the reflector is verified using stereo photogrammetry.

  17. Fabrication and reliable implementation of an ionic polymer-metal composite (IPMC) biaxial bending actuator

    Science.gov (United States)

    Lee, Gil-Yong; Choi, Jung-Oh; Kim, Myeungseon; Ahn, Sung-Hoon

    2011-10-01

    Ionic polymer-metal composites (IPMCs) are one of the most popular types of electro-active polymer actuator, due to their low electric driving potential, large deformation range, and light weight. IPMCs have been used as actuators or sensors in many areas of biomedical and robotic engineering. In this research, IPMCs were studied as a biaxial bending actuator capable of smart and flexible motion. We designed and fabricated this bending actuator and implemented it to have a reliable actuating motion using a systematic approach. The resulting device was bar shaped with a square cross section and had four insulated electrodes on its surface. By applying different voltages to these four electrodes, a biaxial bending motion can be induced. To construct this actuator, several fabrication processes were considered. We modified the Nafion stacking method, and established a complete sequence of actuator fabrication processes. Using these processes, we were able to fabricate an IPMC biaxial bending actuator with both high actuating force and high flexibility. Several experiments were conducted to investigate and verify the performance of the actuator. The IPMC actuator system was modeled from experimentally measured data, and using this actuator model, a closed-loop proportional integral (PI) controller was designed. Reference position tracking performances of open-loop and closed-loop systems were compared. Finally, circular motion tracking performances of the actuator tip were tested under different rotation frequencies and radii of a reference trajectory circle.

  18. Failure of cargo aileron’s actuator

    Directory of Open Access Journals (Sweden)

    G. Zucca

    2014-10-01

    Full Text Available During a ferry flight, in a standard operation condition and at cruising level, a military cargo experienced a double hydraulic system failure due to a structural damage of the dual booster actuator. The booster actuator is the main component in mechanism of aileron’s deflection. The crew was able to arrange an emergency landing thanks to the spare oil onboard: load specialists refilled the hydraulic reservoirs. Due to safety concerns and in order to prevent the possibility of other similar incidents, a technical investigation took place. The study aimed to carry out the analysis of root causes of the actuator failure. The Booster actuator is composed mainly by the piston rod and its aluminum external case (AA7049. The assembly has two bronze caps on both ends. These are fixed in position by means of two retainers. At one end of the actuator case is placed a trunnion: a cylindrical protrusion used as a pivoting point on the aircraft. The fracture was located at one end of the case, on the trunnion side, in correspondence to the cap and over the retainer. One of the two fracture surfaces was found separated to the case and with the cap entangled inside. The fracture surfaces of the external case indicated fatigue crack growth followed by ductile separation. The failure analysis was performed by means of optical, metallographic, digital and electronic microscopy. The collected evidences showed a multiple initiation fracture mechanism. Moreover, 3D scanner reconstruction and numerical simulation demonstrated that dimensional non conformances and thermal loads caused an abnormal stress concentration. Stress concentration was located along the case assy outer surface where the fatigue crack originated. The progressive rupture mechanism grew under cyclical axial load due to the normal operations. Recommendations were issued in order to improve dimensional controls and assembly procedures during production and overhaul activities.

  19. Architecture Optimization of More Electric Aircraft Actuation System

    Institute of Scientific and Technical Information of China (English)

    QI Haitao; FU Yongling; QI Xiaoye; LANG Yan

    2011-01-01

    The optional types of power source and actuator in the aircraft are more and more diverse due to fast development in more electric technology,which makes the combinations of different power sources and actuators become extremely complex in the architecture optimization process of airborne actuation system.The traditional “trial and error” method cannot satisfy the design demands.In this paper,firstly,the composition of more electric aircraft(MEA) flight control actuation system(FCAS) is introduced,and the possible architecture quantity is calculated.Secondly,the evaluation criteria of FCAS architecture with respect to safe reliability,weight and efficiency are proposed,and the evaluation criteria values are calculated in the case that each control surface adopts the same actuator configuration.Finally,the optimization results of MEA FCAS architecture are obtained by applying genetic algorithm(GA).Compared to the traditional actuation system architecture,which only adopts servo valve controlled hydraulic actuators,the weight of the optimized more electric actuation system architecture can be reduced by 6%,and the efficiency can be improved by 30% based on the safe reliability requirements.

  20. Series elastic actuators

    Science.gov (United States)

    Williamson, Matthew M.

    1995-01-01

    This thesis presents the design, construction, control and evaluation of a novel for controlled actuator. Traditional force controlled actuators are designed from the premise that 'Stiffer is better'. This approach gives a high bandwidth system, prone to problems of contact instability, noise, and low power density. The actuator presented in this thesis is designed from the premise that 'Stiffness isn't everything'. The actuator, which incorporates a series elastic element, trades off achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. This thesis reviews related work in robot force control, presents theoretical descriptions of the control and expected performance from a series elastic actuator, and describes the design of a test actuator constructed to gather performance data. Finally the performance of the system is evaluated by comparing the performance data to theoretical predictions.

  1. MEMS fluidic actuator

    Science.gov (United States)

    Kholwadwala, Deepesh K.; Johnston, Gabriel A.; Rohrer, Brandon R.; Galambos, Paul C.; Okandan, Murat

    2007-07-24

    The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

  2. Copper Planar Microcoils Applied to Magnetic Actuation

    CERN Document Server

    Moulin, J; Martincic, E; Dufour-Gergam, E

    2008-01-01

    Recent advances in microtechnology allow realization of planar microcoils. These components are integrated in MEMS as magnetic sensor or actuator. In the latter case, it is necessary to maximize the effective magnetic field which is proportional to the current passing through the copper track and depends on the distance to the generation microcoil. The aim of this work was to determine the optimal microcoil design configuration for magnetic field generation. The results were applied to magnetic actuation, taking into account technological constraints. In particular, we have considered different realistic configurations that involve a magnetically actuated device coupled to a microcoil. Calculations by a semi-analytical method using Matlab software were validated by experimental measurements. The copper planar microcoils are fabricated by U.V. micromoulding on different substrates: flexible polymer (Kapton) and silicate on silicon. They are constituted by a spiral-like continuous track. Their total surface is ...

  3. Magnetic actuators and sensors

    CERN Document Server

    Brauer, John R

    2014-01-01

    An accessible, comprehensive guide on magnetic actuators and sensors, this fully updated second edition of Magnetic Actuators and Sensors includes the latest advances, numerous worked calculations, illustrations, and real-life applications. Covering magnetics, actuators, sensors, and systems, with updates of new technologies and techniques, this exemplary learning tool emphasizes computer-aided design techniques, especially magnetic finite element analysis, commonly used by today's engineers. Detailed calculations, numerous illustrations, and discussions of discrepancies make this text an inva

  4. Remote switch actuator

    Science.gov (United States)

    Haas, Edwin Gerard; Beauman, Ronald; Palo, Jr., Stefan

    2013-01-29

    The invention provides a device and method for actuating electrical switches remotely. The device is removably attached to the switch and is actuated through the transfer of a user's force. The user is able to remain physically removed from the switch site obviating need for protective equipment. The device and method allow rapid, safe actuation of high-voltage or high-current carrying electrical switches or circuit breakers.

  5. Plug & Play Control of Hydraulic Networks

    DEFF Research Database (Denmark)

    Jensen, Tom Nørgaard

    2012-01-01

    Process Control research program, which the work presented here is a part of. An industrial case study involving a large-scale hydraulic network with non-linear dynamics is studied. The hydraulic network underlies a district heating system, which provides heating water to a number of end-users in a city...... structure has the additional benefit that structural changes such as the addition or removal of end-users are easily implementable. In this work, the problem of controlling the pressure drop at the end-users to a constant reference value is considered. This is done by the use of pumps located both...... are considered. Some of the work considers control actions which are constrained to non-negative values only. This is due to the fact that the actuators in this type of system typically consist of centrifugal pumps which are only able to deliver non-negative actuation. Other parts of the work consider control...

  6. Actuator environmental stability

    Science.gov (United States)

    Yoshikawa, Shoko; Farrell, Michael

    2000-06-01

    Various configurations of piezoelectric high strain actuators are available in the market. The influence of humidity at high temperature is not well documented, even though it is an important consideration for actuator performance. This paper describes the testing and results of two different families of actuators; QuickPack products and multilayer actuators, tested under two environments; room temperature low humidity and elevated temperature and humidity (80°C/80%RH). A constant DC load was applied to the QP10N andand QP10Ni products in free condition, while positive only AC field was applied to multilayer actuators, under pre-stressed condition. High field IR was used as the main tool to determine the health of QuickPack products, whereas, in-situ displacement was measured to monitor the health of multilayer actuators. As expected, in both families of actuators, it was shown that the actuator life is significantly reduced when specimens are exposed to humidity at elevated temperature. Improvement of the humidity barrier, thus less moisture penetration, even when electrodes do not contain silver, is expected to prolong life of actuators.

  7. Electrostatically Driven Nanoballoon Actuator.

    Science.gov (United States)

    Barzegar, Hamid Reza; Yan, Aiming; Coh, Sinisa; Gracia-Espino, Eduardo; Dunn, Gabriel; Wågberg, Thomas; Louie, Steven G; Cohen, Marvin L; Zettl, Alex

    2016-11-09

    We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

  8. RESEARCH OF THE DYNAMIC CHARACTERISTICS ON A NEW HYDRAULIC SYSTEM OF ELECTRO-HYDRAULIC HAMMER

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new typed hydraulic system of electro-hydraulic hammer is researched and developed.By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed. The experimental research which is emphasized on the blowing stroke is also performed. It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working. Especially it possesses better dynamic characteristics.

  9. Development of Heavy-Duty and High-Precision Hydraulic Manipulator for Inspection, Maintenance and Decommission of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Uk; Seo, Yong-chil; Jung, Kyung Min; Kim, Chang-hoi; Choi, Byung-seon; Moon, Jei-kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Robotic manipulators have been used for inspection, maintenance and decommission of nuclear power plants because nuclear power plants have high radiation and human workers cannot easily access the plants. And also, to inspecting, maintaining and decommissioning nuclear power plants require various manipulators. Only one manipulator cannot response to many required tasks. The existing manipulators that was used at nuclear power plants can only operate only focused specific task and cannot be used at several tasks. The actuators used at manipulators are varied and many companies sell actuators depending on power, torque and speed. However, the commercial product is not standardized. Therefore, the development of manipulator is time consuming and expensive. The essential item of a manipulator is an actuator module. If actuator module is standardized, it’s easier to develop a manipulator and also maintain a manipulator. Recently, manipulator having high-radiation, high-duty and high-precision is necessary to inspection, maintain and decommissioning of nuclear power plants. Hydraulic actuator has been used to development high-duty manipulator. But control performance of a hydraulic actuator is not better than that of an electric actuator so that hydraulic manipulator cannot easily satisfy the required precision. In this paper, we developed high-duty and high-precision actuator modules and hydraulic manipulator using the developed actuator modules. The developed hydraulic manipulator have a payload of 250kg and a precision of ±1mm. Four modularized hydraulic actuator modules were developed for inspection, maintenance and decommission. Using the developed actuator modules, the manipulator for decommissioning is easily developed. And also, various manipulators having different kinematic structure for specific tasks will be easily developed by using hydraulic modules.

  10. Improving energy efficiency in robot limbs through hydraulic dangle

    Science.gov (United States)

    Whitman, Julian S.; Meller, Mike; Garcia, Ephrahim

    2015-03-01

    Animals often allow their limbs to swing passively under their own inertia. For example, about 40% of a human walking gait consists of the primarily passive swing phase. Current hydraulic robots employ traditional actuation methods in which fluid power is expended for all limb movements, even when passive dynamics could be utilized. "Dangle" is the ability to allow a hydraulic actuator to freely sway in response to external loads, in which both sides of the actuator are disconnected from pressure and connected to the tank. Dangle offers the opportunity for efficiency gains by enabling the use of momentum, gravity, and external loads to move a limb without expending fluid power. To demonstrate these efficiency gains, this paper presents an experiment that compares the fluid power consumed to actuate a two degree of freedom hydraulic leg following a human walking gait cycle trajectory in both a traditional manner and utilizing dangle. It was shown that the use of dangle can decrease fluid power consumption by 20% by utilizing pendular dynamics during the swing phase. At speeds higher than the free dangling rate, more power must be used to maintain the desired trajectory due to damping inherent in the configuration. The use of dangle as a power saving method when driving hydraulic limbs could increase operation time for untethered hydraulic walking robots.

  11. Polymer-based actuators for virtual reality devices

    Science.gov (United States)

    Bolzmacher, Christian; Hafez, Moustapha; Benali Khoudja, Mohamed; Bernardoni, Paul; Dubowsky, Steven

    2004-07-01

    Virtual Reality (VR) is gaining more importance in our society. For many years, VR has been limited to the entertainment applications. Today, practical applications such as training and prototyping find a promising future in VR. Therefore there is an increasing demand for low-cost, lightweight haptic devices in virtual reality (VR) environment. Electroactive polymers seem to be a potential actuation technology that could satisfy these requirements. Dielectric polymers developed the past few years have shown large displacements (more than 300%). This feature makes them quite interesting for integration in haptic devices due to their muscle-like behaviour. Polymer actuators are flexible and lightweight as compared to traditional actuators. Using stacks with several layers of elatomeric film increase the force without limiting the output displacement. The paper discusses some design methods for a linear dielectric polymer actuator for VR devices. Experimental results of the actuator performance is presented.

  12. Curved Piezoelectric Actuators for Stretching Optical Fibers

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.

  13. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

  14. Pneumatically actuated hand tool

    NARCIS (Netherlands)

    Cool, J.C.; Rijnsaardt, K.A.

    1996-01-01

    Abstract of NL 9401195 (A) Pneumatically actuated hand tool for carrying out a mechanical operation, provided with an exchangeable gas cartridge in which the gas which is required for pneumatic actuation is stored. More particularly, the hand tool is provided with at least one pneumatic motor, at

  15. Sensors and actuators, Twente

    NARCIS (Netherlands)

    Bergveld, P.

    1989-01-01

    This paper describes the organization and the research programme of the Sensor and Actuator (S&A) Research Unit of the University of Twente, Enschede, the Netherlands. It includes short descriptions of all present projects concerning: micromachined mechanical sensors and actuators, optical sensors,

  16. Electrorheological fluid-actuated microfluidic pump

    Science.gov (United States)

    Liu, Liyu; Chen, Xiaoqing; Niu, Xize; Wen, Weijia; Sheng, Ping

    2006-08-01

    The authors report the design and implementation of an electrorheological (ER) fluid-actuated microfluidic pump, with programmable digital control. Our microfluidic pump has a multilayered structure fabricated on polydimethylsiloxane by soft-lithographic technique. The ER microfluidic pump exhibits good performance at high pumping frequencies and uniform liquid flow characteristics. It can be easily integrated with other microfluidic components. The programmable control also gives the device flexibility in its operations.

  17. Conjugated Polymers as Actuators: Modes of Actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  18. Conjugated polymers as actuators: modes of actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2007-01-01

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  19. Active Vibration Suppression of a 3-DOF Flexible Parallel Manipulator Using Efficient Modal Control

    OpenAIRE

    Quan Zhang; Jiamei Jin; Jianhui Zhang; Chunsheng Zhao

    2014-01-01

    This paper addresses the dynamic modeling and efficient modal control of a planar parallel manipulator (PPM) with three flexible linkages actuated by linear ultrasonic motors (LUSM). To achieve active vibration control, multiple lead zirconate titanate (PZT) transducers are mounted on the flexible links as vibration sensors and actuators. Based on Lagrange’s equations, the dynamic model of the flexible links is derived with the dynamics of PZT actuators incorporated. Using the assumed mode me...

  20. Hydraulic Yaw System

    DEFF Research Database (Denmark)

    Stubkier, Søren; Pedersen, Henrik C.; Mørkholt, M.

    As wind turbines increase in size, combined with increased lifetime demands, new methods for load reduction needs to be examined. One method is to make the yaw system of the turbine soft/flexible and hereby dampen the loads to the system, which is the focus of the current paper. By utilizing...... the HAWC2 aeroelastic code and an extended model of the NREL 5MW turbine combined with a simplified linear model of the turbine, the parameters of the soft yaw system are optimized to reduce loading in critical components. Results shows that a significant reduction in fatigue and extreme loads to the yaw...... system and rotor shaft when utilizing the soft yaw drive concept compared to the original stiff yaw system. The physical demands of the hydraulic yaw system are furthermore examined for a life time of 20 years. Based on the extrapolated loads, the duty cycles show that it is possible to construct...

  1. An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology

    Science.gov (United States)

    Liu, Guojun; Zhang, Yanyan; Liu, Jianfang; Li, Jianqiao; Tang, Chunxiu; Wang, Tengfei; Yang, Xuhao

    2016-01-01

    An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT) actuation and electrorheological fluids (ERFs) control technology is presented. The actuator consists of actuation unit (PZT stack pump), fluid control unit (ERFs valve), and execution unit (hydraulic actuator). In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type) of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator. PMID:27022234

  2. An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology.

    Science.gov (United States)

    Liu, Guojun; Zhang, Yanyan; Liu, Jianfang; Li, Jianqiao; Tang, Chunxiu; Wang, Tengfei; Yang, Xuhao

    2016-01-01

    An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT) actuation and electrorheological fluids (ERFs) control technology is presented. The actuator consists of actuation unit (PZT stack pump), fluid control unit (ERFs valve), and execution unit (hydraulic actuator). In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type) of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

  3. An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology

    Directory of Open Access Journals (Sweden)

    Guojun Liu

    2016-01-01

    Full Text Available An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT actuation and electrorheological fluids (ERFs control technology is presented. The actuator consists of actuation unit (PZT stack pump, fluid control unit (ERFs valve, and execution unit (hydraulic actuator. In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

  4. Cryogenic Piezoelectric Actuator

    Science.gov (United States)

    Jiang, Xiaoning; Cook, William B.; Hackenberger, Wesley S.

    2009-01-01

    In this paper, PMN-PT single crystal piezoelectric stack actuators and flextensional actuators were designed, prototyped and characterized for space optics applications. Single crystal stack actuators with footprint of 10 mm x10 mm and the height of 50 mm were assembled using 10 mm x10mm x0.15mm PMN-PT plates. These actuators showed stroke > 65 - 85 microns at 150 V at room temperature, and > 30 microns stroke at 77 K. Flextensional actuators with dimension of 10mm x 5 mm x 7.6 mm showed stroke of >50 microns at room temperature at driving voltage of 150 V. A flextensional stack actuator with dimension of 10 mm x 5 mm x 47 mm showed stroke of approx. 285 microns at 150 V at room temperature and > 100 microns at 77K under driving of 150 V should be expected. The large cryogenic stroke and high precision of these actuators are promising for cryogenic optics applications.

  5. Design of a smart bidirectional actuator for space operation

    Science.gov (United States)

    Saggin, Bortolino; Scaccabarozzi, Diego; Tarbini, Marco; Magni, Marianna; Biffi, Carlo Alberto; Tuissi, Ausonio

    2017-03-01

    A common need for space borne instruments, satellites and planetary exploration payloads is the usage of compact, light and low power actuators. In the recent years, this need has been partially solved by the development of customized solutions with an increasing usage of smart materials. A linear bidirectional actuator based on shape memory alloy technology is presented in this work. The device has been conceived to lock the double-pendulum scanning mechanism of a miniaturized Fourier transform spectrometer for planetary observation. The mechanism class is that of pin pullers, with the pin locking the movable components of the spectrometer during launch and landing phases. The proposed mechanism, differently from available off-the-shelf devices, allows multiple actuations without the need of manual resetting. Moreover, the device requires to be powered only to change its status. An appealing feature of the adopted concept is that the actuation is intrinsically shock-less, a key requirement for deployment of devices sensitive to mechanical vibration and shocks. All these characteristics, in addition to the design flexibility of the proposed concept in terms of achievable forces and strokes, make the designed actuator promising for many different applications, from space to ground. The designed bidirectional actuator provides 0.6 mm stroke and a 50 N preload but it represents just an example of implementation for the proposed concept. Structural design of the functional elastic components and SMA alloy characterization have guided the actuator development. A mockup of the actuator has been manufactured and the predicted performances preliminary validated.

  6. Electrothermal Actuators for SiO2 Photonic MEMS

    Directory of Open Access Journals (Sweden)

    Tjitte-Jelte Peters

    2016-11-01

    Full Text Available This paper describes the design, fabrication and characterization of electrothermal bimorph actuators consisting of polysilicon on top of thick (>10 μ m silicon dioxide beams. This material platform enables the integration of actuators with photonic waveguides, producing mechanically-flexible photonic waveguide structures that are positionable. These structures are explored as part of a novel concept for highly automated, sub-micrometer precision chip-to-chip alignment. In order to prevent residual stress-induced fracturing that is associated with the release of thick oxide structures from a silicon substrate, a special reinforcement method is applied to create suspended silicon dioxide beam structures. The characterization includes measurements of the post-release deformation (i.e., without actuation, as well as the deflection resulting from quasi-static and dynamic actuation. The post-release deformation reveals a curvature, resulting in the free ends of 800 μ m long silicon dioxide beams with 5 μ m-thick polysilicon to be situated approximately 80 μ m above the chip surface. Bimorph actuators that are 800 μ m in length produce an out-of-plane deflection of approximately 11 μ m at 60 mW dissipated power, corresponding to an estimated 240 ∘ C actuator temperature. The delivered actuation force of the 800 μ m-long bimorph actuators having 5 μ m-thick polysilicon is calculated to be approximately 750 μN at 120 mW .

  7. Propulsive performance of an under-actuated robotic ribbon fin.

    Science.gov (United States)

    Liu, Hanlin; Curet, Oscar M

    2017-06-02

    Many aquatic animals propelled by elongated undulatory fins can perform complex maneuvers and swim with high efficiency at low speeds. In this propulsion, one or multiple waves travel along an elastic fin composed of flexible rays. In this study, we explore the potential benefits or disadvantages of passive fin motion based on the coupling of fluid-structure interactions and elasto-mechanical responses of the undulatory fin. The motivation is to understand how an under-actuated undulating fin can modify its active and passive fin motion to effectively control the hydrodynamic force and propulsive efficiency. We study the kinematics and propulsive performance of an under-actuated ribbon fin using a robotic device. During two experimental sets for fully-actuated fin and under-actuated fin respectively, we measured fin kinematics, surge forces and power consumption. Our results show that under-actuated fin can generate smaller thrust but consume less power comparing to a fully-actuated counterpart. The thrust generated by an under-actuated fin scales similarly to a fully-actuated fin-linear with the enclosed area and quadratic with the relative velocity. Power consumption scales with cube of lateral tangential velocity. Furthermore, we find that the under-actuated fin can keep the same propulsive efficiency as the fully-actuated fin at low relative velocities. This finding has profound implications to both natural swimmers and underwater vehicles using undulating fin-based propulsion, as it suggests that they can potentially exploit passive fin motion without decrementing propulsive efficiency. For underwater vehicles with undulatory fins, an under-actuated design can greatly simplify the mechanical design and control complexity of a versatile propulsion system.

  8. System Topology Optimization - An Approach to System Design of Electro-Hydraulic-Mechanical Systems

    DEFF Research Database (Denmark)

    Andersen, T. O.; Hansen, M. R.; Conrad, Finn

    2003-01-01

    design the procedure attempts to find the optimal topology and the related parameters. The topology considerations comprise the type of hydraulic pump, the employment of knee linkages or not as well as the type of hydraulic actuators. The design variables also include the signals to the proportional......The current paper presents an approach to system design of combined electro-hydraulic-mechanical systems. The approach is based on the concurrent handling of the topology as well as the design parameters of the mechanical, hydraulic and controller sub- systems, respectively. Based on an initial...... valve in a number of predefined load cases as well as the hydraulic and mechanical parameters....

  9. Active control of structural vibration by piezoelectric stack actuators

    Institute of Scientific and Technical Information of China (English)

    NIU Jun-chuan; ZHAO Guo-qun; HU Xia-xia

    2005-01-01

    This paper presents a general analytical model of flexible isolation system for application to the installation of high-speed machines and lightweight structures. Piezoelectric stack actuators are employed in the model to achieve vibration control of flexible structures, and dynamic characteristics are also investigated. Mobility technique is used to derive the governing equations of the system. The power flow transmitted into the foundation is solved and considered as a cost function to achieve optimal control of vibration isolation. Some numerical simulations revealed that the analytical model is effective as piezoelectric stack actuators can achieve substantial vibration attenuation by selecting proper value of the input voltage.

  10. Pressure regulation in nonlinear hydraulic networks by positive controls

    NARCIS (Netherlands)

    De Persis, Claudio; Skovmose Kallesøe, Carsten

    2009-01-01

    We report on our investigation of an industrial case study of a system distributed over a network, namely a large-scale hydraulic network which underlies a district heating system. The network comprises an arbitrarily large number of end-users and actuators distributed along the network. After intro

  11. Low duty-cycle pulsed power actuation applications

    Science.gov (United States)

    Merryman, Stephen A.; Owens, W. Todd

    1995-01-01

    Electrical actuator systems are being pursued as alternatives to hydraulic systems to reduce maintenance time, weight, and costs while increasing reliability. Additionally, safety and environmental hazards associated with the hydraulic fluids can be eliminated. For most actuation systems, the actuation process is typically pulsed with high peak power requirements but with relatively modest average power levels. For example, the peak power requirements for the shuttle solid rocket booster actuators are approximately 40 kW for one or two seconds, but the average power over the 130 second burn time is on the order of 7 kW. The power-time requirements for electrical actuators are characteristic of pulsed power technologies where the source can be sized for the average power levels while providing the capability to achieve the peak requirements. Among the options for the power source are battery systems, capacitor systems or battery-capacitor hybrid systems. Battery technologies are energy dense but deficient in power density; capacitor technologies are power dense but limited by energy density. The battery-capacitor hybrid system uses the battery to supply the average power and the capacitor to meet the peak demands. In this research effort, Chemical Double Layer (CDL) capacitor technology is being applied in the design and development of power sources for electrical actuators. CDL capacitors have many properties that make them well-suited for actuator applications. They have the highest demonstrated energy density for capacitive storage (about a factor of 5-10 less than NiCd batteries), have power densities 50 times greater than NiCd batteries, are capable of 500,000 charge-discharge cycles, can be charged at extremely high rates, and have non-explosive failure modes. Thus, CDL capacitors exhibit a combination of desirable battery and capacitor characteristics. Specifically, electrode technology patented by Auburn University is being used in the development of CDL

  12. Magnetically Actuated Seal

    Science.gov (United States)

    Pinera, Alex

    2013-01-01

    This invention is a magnetically actuated seal in which either a single electromagnet, or multiple electromagnets, are used to control the seal's position. This system can either be an open/ close type of system or an actively controlled system.

  13. Magnetically Actuated Seal Project

    Data.gov (United States)

    National Aeronautics and Space Administration — FTT proposes development of a magnetically actuated dynamic seal. Dynamic seals are used throughout the turbopump in high-performance, pump-fed, liquid rocket...

  14. Muscle Motion Solenoid Actuator

    Science.gov (United States)

    Obata, Shuji

    It is one of our dreams to mechanically recover the lost body for damaged humans. Realistic humanoid robots composed of such machines require muscle motion actuators controlled by all pulling actions. Particularly, antagonistic pairs of bi-articular muscles are very important in animal's motions. A system of actuators is proposed using the electromagnetic force of the solenoids with the abilities of the stroke length over 10 cm and the strength about 20 N, which are needed to move the real human arm. The devised actuators are based on developments of recent modern electro-magnetic materials, where old time materials can not give such possibility. Composite actuators are controlled by a high ability computer and software making genuine motions.

  15. Tendon Driven Finger Actuation System

    Science.gov (United States)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); hide

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  16. Modeling and Investigation of Electromechanical Valve Train Actuator at simulated Pressure conditions

    DEFF Research Database (Denmark)

    Habib, Tufail

    2012-01-01

    In an electromechanical valve actuated engine, the valves are driven by solenoid-type actuators and cam-shaft is eliminated. Control of each valve provides flexibility in valve timings over all engine conditions and achieves the benefits of variable valve timing(VVT). This paper is about investig...

  17. Actuation of polypyrrole nanowires

    Science.gov (United States)

    Lee, Alexander S.; Peteu, Serban F.; Ly, James V.; Requicha, Aristides A. G.; Thompson, Mark E.; Zhou, Chongwu

    2008-04-01

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 µm, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  18. Compact electrostatic comb actuator

    Science.gov (United States)

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  19. Actuation of polypyrrole nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Alexander S; Peteu, Serban F; Ly, James V; Requicha, Aristides A G; Thompson, Mark E; Zhou Chongwu [Laboratory for Molecular Robotics, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: requicha@usc.edu

    2008-04-23

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 {mu}m, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  20. Actuation of polypyrrole nanowires.

    Science.gov (United States)

    Lee, Alexander S; Peteu, Serban F; Ly, James V; Requicha, Aristides A G; Thompson, Mark E; Zhou, Chongwu

    2008-04-23

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 µm, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  1. Movable MEMS Devices on Flexible Silicon

    KAUST Repository

    Ahmed, Sally

    2013-05-05

    Flexible electronics have gained great attention recently. Applications such as flexible displays, artificial skin and health monitoring devices are a few examples of this technology. Looking closely at the components of these devices, although MEMS actuators and sensors can play critical role to extend the application areas of flexible electronics, fabricating movable MEMS devices on flexible substrates is highly challenging. Therefore, this thesis reports a process for fabricating free standing and movable MEMS devices on flexible silicon substrates; MEMS flexure thermal actuators have been fabricated to illustrate the viability of the process. Flexure thermal actuators consist of two arms: a thin hot arm and a wide cold arm separated by a small air gap; the arms are anchored to the substrate from one end and connected to each other from the other end. The actuator design has been modified by adding etch holes in the anchors to suit the process of releasing a thin layer of silicon from the bulk silicon substrate. Selecting materials that are compatible with the release process was challenging. Moreover, difficulties were faced in the fabrication process development; for example, the structural layer of the devices was partially etched during silicon release although it was protected by aluminum oxide which is not attacked by the releasing gas . Furthermore, the thin arm of the thermal actuator was thinned during the fabrication process but optimizing the patterning and etching steps of the structural layer successfully solved this problem. Simulation was carried out to compare the performance of the original and the modified designs for the thermal actuators and to study stress and temperature distribution across a device. A fabricated thermal actuator with a 250 μm long hot arm and a 225 μm long cold arm separated by a 3 μm gap produced a deflection of 3 μm before silicon release, however, the fabrication process must be optimized to obtain fully functioning

  2. Adaptive Strategies for Controls of Flexible Arms. Ph.D. Thesis

    Science.gov (United States)

    Yuan, Bau-San

    1989-01-01

    An adaptive controller for a modern manipulator has been designed based on asymptotical stability via the Lyapunov criterion with the output error between the system and a reference model used as the actuating control signal. Computer simulations were carried out to test the design. The combination of the adaptive controller and a system vibration and mode shape estimator show that the flexible arm should move along a pre-defined trajectory with high-speed motion and fast vibration setting time. An existing computer-controlled prototype two link manipulator, RALF (Robotic Arm, Large Flexible), with a parallel mechanism driven by hydraulic actuators was used to verify the mathematical analysis. The experimental results illustrate that assumed modes found from finite element techniques can be used to derive the equations of motion with acceptable accuracy. The robust adaptive (modal) control is implemented to compensate for unmodelled modes and nonlinearities and is compared with the joint feedback control in additional experiments. Preliminary results show promise for the experimental control algorithm.

  3. Development of ICPF Actuated Underwater Microrobots

    Institute of Scientific and Technical Information of China (English)

    Xiuo-Fen Ye; Bao-Feng Gao; Shu-Xiang Guo; Li-Quan Wang

    2006-01-01

    It is our target to develop underwater microrobots for medical and industrial applications. This kind of underwater microrobots should have the characteristics of flexibility, good response and safety. Its structure should be simple and it can be driven by low voltage and produces no pollution or noise. The low actuating voltage and quick bending responses of Ionic Conducting Polymer Film (ICPF) are considered very useful and attractive for constructing various types of actuators and sensors. In this paper, we will first study the characteristics of the ICPF actuator used in underwater microrobot to realize swimming and walking. Then, we propose a new prototype model of underwater swimming microrobot utilizing only one piece of ICPF as the servo actuator. Through theoretic analysis, the motion mechanism of the microrobot is illustrated. It can swim forward and vertically. The relationships between moving speed and signal voltage amplitude and signal frequency is obtained after experimental study. Lastly, we present a novel underwater crab-like walking microrobot named crabliker-1. It has eight legs, and each leg is made up of two pieces of ICPF. Three sample processes of the octopod gait are proposed with a new analyzing method. The experimental results indicate that the crab-like underwater microrobot can perform transverse and rotation movement when the legs of the crab collaborate.

  4. Carbon nanotube and graphene-based bioinspired electrochemical actuators.

    Science.gov (United States)

    Kong, Lirong; Chen, Wei

    2014-02-01

    Bio-inspired actuation materials, also called artificial muscles, have attracted great attention in recent decades for their potential application in intelligent robots, biomedical devices, and micro-electro-mechanical systems. Among them, ionic polymer metal composite (IPMC) actuator has been intensively studied for their impressive high-strain under low voltage stimulation and air-working capability. A typical IPMC actuator is composed of one ion-conductive electrolyte membrane laminated by two electron-conductive metal electrode membranes, which can bend back and forth due to the electrode expansion and contraction induced by ion motion under alternating applied voltage. As its actuation performance is mainly dominated by electrochemical and electromechanical process of the electrode layer, the electrode material and structure become to be more crucial to higher performance. The recent discovery of one dimensional carbon nanotube and two dimensional graphene has created a revolution in functional nanomaterials. Their unique structures render them intriguing electrical and mechanical properties, which makes them ideal flexible electrode materials for IPMC actuators in stead of conventional metal electrodes. Currently although the detailed effect caused by those carbon nanomaterial electrodes is not very clear, the presented outstanding actuation performance gives us tremendous motivation to meet the challenge in understanding the mechanism and thus developing more advanced actuator materials. Therefore, in this review IPMC actuators prepared with different kinds of carbon nanomaterials based electrodes or electrolytes are addressed. Key parameters which may generate important influence on actuation process are discussed in order to shed light on possible future research and application of the novel carbon nanomateials based bio-inspired electrochemical actuators.

  5. Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

    Science.gov (United States)

    Yoon, K. J.; Park, K. H.; Lee, S. K.; Goo, N. S.; Park, H. C.

    2004-06-01

    This paper describes an analytical design model for a layered piezo-composite unimorph actuator and its numerical and experimental verification using a LIPCA (lightweight piezo-composite curved actuator) that is lighter than other conventional piezo-composite type actuators. The LIPCA is composed of top fiber composite layers with high modulus and low CTE (coefficient of thermal expansion), a middle PZT ceramic wafer, and base layers with low modulus and high CTE. The advantages of the LIPCA design are to replace the heavy metal layer of THUNDER by lightweight fiber-reinforced plastic layers without compromising the generation of high force and large displacement and to have design flexibility by selecting the fiber direction and the number of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use a resin prepreg system. A piezo-actuation model for a laminate with piezo-electric material layers and fiber composite layers is proposed to predict the curvature and residual stress of the LIPCA. To predict the actuation displacement of the LIPCA with curvature, a finite element analysis method using the proposed piezo-actuation model is introduced. The predicted deformations are in good agreement with the experimental ones.

  6. High-pressure microhydraulic actuator

    Science.gov (United States)

    Mosier, Bruce P [San Francisco, CA; Crocker, Robert W [Fremont, CA; Patel, Kamlesh D [Dublin, CA

    2008-06-10

    Electrokinetic ("EK") pumps convert electric to mechanical work when an electric field exerts a body force on ions in the Debye layer of a fluid in a packed bed, which then viscously drags the fluid. Porous silica and polymer monoliths (2.5-mm O.D., and 6-mm to 10-mm length) having a narrow pore size distribution have been developed that are capable of large pressure gradients (250-500 psi/mm) when large electric fields (1000-1500 V/cm) are applied. Flowrates up to 200 .mu.L/min and delivery pressures up to 1200 psi have been demonstrated. Forces up to 5 lb-force at 0.5 mm/s (12 mW) have been demonstrated with a battery-powered DC-DC converter. Hydraulic power of 17 mW (900 psi@ 180 uL/min) has been demonstrated with wall-powered high voltage supplies. The force and stroke delivered by an actuator utilizing an EK pump are shown to exceed the output of solenoids, stepper motors, and DC motors of similar size, despite the low thermodynamic efficiency.

  7. Behavior of ionic conducting IPN actuators in simulated space conditions

    Science.gov (United States)

    Fannir, Adelyne; Plesse, Cédric; Nguyen, Giao T. M.; Laurent, Elisabeth; Cadiergues, Laurent; Vidal, Frédéric

    2016-04-01

    The presentation focuses on the performances of flexible all-polymer electroactive actuators under space-hazardous environmental factors in laboratory conditions. These bending actuators are based on high molecular weight nitrile butadiene rubber (NBR), poly(ethylene oxide) (PEO) derivative and poly(3,4-ethylenedioxithiophene) (PEDOT). The electroactive PEDOT is embedded within the PEO/NBR membrane which is subsequently swollen with an ionic liquid as electrolyte. Actuators have been submitted to thermal cycling test between -25 to 60°C under vacuum (2.4 10-8 mbar) and to ionizing Gamma radiations at a level of 210 rad/h during 100 h. Actuators have been characterized before and after space environmental condition ageing. In particular, the viscoelasticity properties and mechanical resistance of the materials have been determined by dynamic mechanical analysis and tensile tests. The evolution of the actuation properties as the strain and the output force have been characterized as well. The long-term vacuuming, the freezing temperature and the Gamma radiations do not affect significantly the thermomechanical properties of conducting IPNs actuators. Only a slight decrease on actuation performances has been observed.

  8. Tethered actuator for vibration control of space structures

    Science.gov (United States)

    Fujii, H. A.; Sugimoto, Y.; Watanabe, T.; Kusagaya, T.

    2015-12-01

    Effectiveness of a micro-tension actuator for vibration control of such flexible space structures as the tethered space solar power satellites is experimentally studied on the ground. A flexible leverage is employed as the micro-tension actuator in order to control the microtension of tether. The flexible leverage is connected through a tether to the flexible beam as an experimental model of the flexible solar panel with the low first modal frequency of order 1 Hz. The nonlinearity of the flexible tether is taken into account for the vibration control since the tether becomes ineffective when it slacks, i.e., when it is tension-free. The feedback controller is designed by means of the Mission Function control algorithm. Flexural rigidity of the flexible leverage plays an important role in the vibration suppression and is studied experimentally to shed light on the effectiveness of the leverages with five different kinds of rigidity. The experimental results show not only the effect of the flexural rigidity of the flexible leverage on the control performance of the vibration suppression but also the importance of selection of the rigidity to control the vibration of tethered flexible space structures through the microtension of tethers in space.

  9. Energy efficient fluid powered linear actuator with variable area

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Randall F.; Love, Lonnie J.

    2016-09-13

    Hydraulic actuation systems having variable displacements and energy recovery capabilities include cylinders with pistons disposed inside of barrels. When operating in energy consuming modes, high speed valves pressurize extension chambers or retraction chambers to provide enough force to meet or counteract an opposite load force. When operating in energy recovery modes, high speed valves return a working fluid from extension chambers or retraction chambers, which are pressurized by a load, to an accumulator for later use.

  10. Grasp Assist Device with Shared Tendon Actuator Assembly

    Science.gov (United States)

    Ihrke, Chris A. (Inventor); Bergelin, Bryan J. (Inventor); Bridgwater, Lyndon (Inventor)

    2015-01-01

    A grasp assist device includes a glove with first and second tendon-driven fingers, a tendon, and a sleeve with a shared tendon actuator assembly. Tendon ends are connected to the respective first and second fingers. The actuator assembly includes a drive assembly having a drive axis and a tendon hook. The tendon hook, which defines an arcuate surface slot, is linearly translatable along the drive axis via the drive assembly, e.g., a servo motor thereof. The flexible tendon is routed through the surface slot such that the surface slot divides the flexible tendon into two portions each terminating in a respective one of the first and second ends. The drive assembly may include a ball screw and nut. An end cap of the actuator assembly may define two channels through which the respective tendon portions pass. The servo motor may be positioned off-axis with respect to the drive axis.

  11. Robot Arm with Tendon Connector Plate and Linear Actuator

    Science.gov (United States)

    Ihrke, Chris A. (Inventor); Diftler, Myron A. (Inventor); Bridgwater, Lyndon (Inventor); Nguyen, Vienny (Inventor); Millerman, Alexander (Inventor)

    2014-01-01

    A robotic system includes a tendon-driven end effector, a linear actuator, a flexible tendon, and a plate assembly. The linear actuator assembly has a servo motor and a drive mechanism, the latter of which translates linearly with respect to a drive axis of the servo motor in response to output torque from the servo motor. The tendon connects to the end effector and drive mechanism. The plate assembly is disposed between the linear actuator assembly and the tendon-driven end effector and includes first and second plates. The first plate has a first side that defines a boss with a center opening. The second plate defines an accurate through-slot having tendon guide channels. The first plate defines a through passage for the tendon between the center opening and a second side of the first plate. A looped end of the flexible tendon is received within the tendon guide channels.

  12. Digital Actuator Technology

    Energy Technology Data Exchange (ETDEWEB)

    Ken Thomas; Ted Quinn; Jerry Mauck; Richard Bockhorst

    2014-09-01

    There are significant developments underway in new types of actuators for power plant active components. Many of these make use of digital technology to provide a wide array of benefits in performance of the actuators and in reduced burden to maintain them. These new product offerings have gained considerable acceptance in use in process plants. In addition, they have been used in conventional power generation very successfully. This technology has been proven to deliver the benefits promised and substantiate the claims of improved performance. The nuclear industry has been reluctant to incorporate digital actuator technology into nuclear plant designs due to concerns due to a number of concerns. These could be summarized as cost, regulatory uncertainty, and a certain comfort factor with legacy analog technology. The replacement opportunity for these types of components represents a decision point for whether to invest in more modern technology that would provide superior operational and maintenance benefits. Yet, the application of digital technology has been problematic for the nuclear industry, due to qualification and regulatory issues. With some notable exceptions, the result has been a continuing reluctance to undertake the risks and uncertainties of implementing digital actuator technology when replacement opportunities present themselves. Rather, utilities would typically prefer to accept the performance limitations of the legacy analog actuator technologies to avoid impacts to project costs and schedules. The purpose of this report is to demonstrate that the benefits of digital actuator technology can be significant in terms of plant performance and that it is worthwhile to address the barriers currently holding back the widespread development and use of this technology. It addresses two important objectives in pursuit of the beneficial use of digital actuator technology for nuclear power plants: 1. To demonstrate the benefits of digital actuator

  13. Force Control Strategies in Hydraulically Actuated Legged Robots

    Directory of Open Access Journals (Sweden)

    Hector Montes

    2016-03-01

    Full Text Available In this contribution, several strategies of force control have been proposed to be implemented and evaluated in ROBOCLIMBER, a quadruped robot of large dimensions. A first group of strategies proposed in this paper is based on impedance control, which is intended to adapt the foot-ground contact forces according to the experimentally specified damping ratio and the undamped natural frequency. A second control strategy of interest for many practical cases is called the parallel force/position control, which has one inner loop position control and two external control loops, one of force and another of position. A third group of control strategies is the posture stabilization for ROBOCLIMBER using the feedback of the ZMP calculation and the position of its legs. Finally, a control strategy for the control of a quasi-static gait using ZMP feedback is proposed and tested by simulation.

  14. Discrete Learning Control with Application to Hydraulic Actuators

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Pedersen, Henrik Clemmensen; Hansen, Michael R.

    2015-01-01

    In this paper the robustness of a class of learning control algorithms to state disturbances, output noise, and errors in initial conditions is studied. We present a simple learning algorithm and exhibit, via a concise proof, bounds on the asymptotic trajectory errors for the learned input and th...

  15. Flexible Structural-Health-Monitoring Sheets

    Science.gov (United States)

    Qing, Xinlin; Kuo, Fuo

    2008-01-01

    A generic design for a type of flexible structural-health-monitoring sheet with multiple sensor/actuator types and a method of manufacturing such sheets has been developed. A sheet of this type contains an array of sensing and/or actuation elements, associated wires, and any other associated circuit elements incorporated into various flexible layers on a thin, flexible substrate. The sheet can be affixed to a structure so that the array of sensing and/or actuation elements can be used to analyze the structure in accordance with structural-health-monitoring techniques. Alternatively, the sheet can be designed to be incorporated into the body of the structure, especially if the structure is made of a composite material. Customarily, structural-health monitoring is accomplished by use of sensors and actuators arrayed at various locations on a structure. In contrast, a sheet of the present type can contain an entire sensor/actuator array, making it unnecessary to install each sensor and actuator individually on or in a structure. Sensors of different types such as piezoelectric and fiber-optic can be embedded in the sheet to form a hybrid sensor network. Similarly, the traces for electric communication can be deposited on one or two layers as required, and an entirely separate layer can be employed to shield the sensor elements and traces.

  16. Controllability and observability for flexible spacecraft

    Science.gov (United States)

    Hughes, P. C.; Skelton, R. E.

    1979-01-01

    Current interest in extended sensing and actuation for the control of flexible spacecraft has led to the use of modern multivariable control theory and the associated concepts of controllability and observability. This paper shows how to evaluate these properties on a mode-by-mode basis for flexible spacecraft control analysis. Relatively simple criteria are derived which indicate the degree of controllability (observability) of each mode in simple literal terms. These criteria provide physical insight and practical guidance on the type, number, and positioning of sensors and actuators. The results are interpreted for force and torque actuators, and for attitude and deformation measurements. To illustrate these ideas, sample controllability and observability 'surfaces' are presented for the Purdue generic flexible spacecraft model.

  17. Continuous compliance compensation of position-dependent flexible structures

    NARCIS (Netherlands)

    Kontaras, Nikolaos; Heertjes, Marcel; Zwart, Hans

    2016-01-01

    The implementation of lightweight high-performance motion systems in lithography and other applications imposes lower requirements on actuators, amplifiers, and cooling. However, the decreased stiffness of lightweight designs increases the effect of structural flexibilities especially when the point

  18. Flexible Flatfoot

    Science.gov (United States)

    ... this page. Please enable Javascript in your browser. Flexible Flatfoot What Is Flatfoot? Flatfoot is often a ... may develop as a result of a flatfoot. Flexible Flatfoot Flexible flatfoot is one of the most ...

  19. Magnetic Actuators and Sensors

    Science.gov (United States)

    Brauer, John R.

    2005-12-01

    Magnetic actuators and sensors are needed to enable computer and manual control of motion. Magnetic actuators allow a small electrical signal to move small or large objects. To sense the amount of motion, magnetic sensors are frequently used. This book provides the most up-to-date coverage of topics important to modern engineers, both electrical and mechanical. The author includes the latest findings and design techniques from computer models. The latest software tools are used.

  20. Actuator concepts and mechatronics

    Science.gov (United States)

    Gilbert, Michael G.; Horner, Garnett C.

    1998-06-01

    Mechatronic design implies the consideration of integrated mechanical, electrical, and local control characteristics in electromechanical device design. In this paper, mechatronic development of actuation device concepts for active aircraft aerodynamic flow control are presented and discussed. The devices are intended to be embedded in aircraft aerodynamic surfaces to provide zero-net-momentum jets or additional flow-vorticity to control boundary layers and flow- separation. Two synthetic jet device prototypes and one vorticity-on-demand prototype currently in development are described in the paper. The aspects of actuation materials, design approaches to generating jets and vorticity, and the integration of miniaturized electronics are stressed.

  1. Fault tolerant linear actuator

    Science.gov (United States)

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  2. 柔性航天器姿控执行机构微振动集中隔离与分散隔离对比研究%Comparison of concentrated and distributed isolations of micro vibrations in flexible spacecraft attitude actuators

    Institute of Scientific and Technical Information of China (English)

    李静; 庞岩; 冯咬齐; 刘磊

    2016-01-01

    The attitude stability of flexible spacecrafts is reduced because of micro vibrations resulting from rotating attitude control actuators. In this paper, the concentrated vibration isolation and the distributed vibration isolation are studied in the context of high stability pointing. At first, the attitude dynamics model for the flexible spacecraft containing vibration isolators is established. Then, the performances of the passive concentrated vibration isolation and the distributed vibration isolation for the attitude actuators are compared by using the simulation method. It is indicated that by using high-stiffness isolators, the concentrated vibration isolation has a similar performance as the distributed vibration isolation in the satellite maneuvering processes. Using the low-stiffness isolators, the concentrated vibration isolation loses stability more easily than the distributed vibration isolation. The concentrated and distributed vibration isolations have similar performances for attitude stabilizing with both the high-stiffness or the low-stiffness isolators.%姿控执行机构高速旋转诱发的微振动会降低柔性航天器姿态稳定度.为实现高稳指向,文章研究了姿控执行机构的集中隔振与分散隔振技术.首先建立包含隔振器的柔性航天器姿态动力学模型;然后仿真研究航天器在作大角度机动和稳定控制两种工况下,姿控执行机构的两种隔振方案的性能,并进行了对比分析.研究结果表明:航天器进行大角度机动时,对于高刚度隔振器,两种隔振均具有稳定性,并且指向控制性能相似;对于低刚度隔振器,集中隔振较分散隔振容易失稳;在稳定控制工况下,对于高刚度隔振器和低刚度隔振器,两种隔振性能基本一致.

  3. Design of a power-asymmetric actuator for a transtibial prosthesis.

    Science.gov (United States)

    Bartlett, Harrison L; Lawson, Brian E; Goldfarb, Michael

    2017-07-01

    This paper presents the design and characterization of a power-asymmetric actuator for a transtibial prosthesis. The device is designed to provide the combination of: 1) joint locking, 2) high power dissipation, and 3) low power generation. This actuator functionality allows for a prosthesis to be designed with minimal mass and power consumption relative to a fully-powered robotic prosthesis while maintaining much of the functionality necessary for activities of daily living. The actuator achieves these design characteristics while maintaining a small form factor by leveraging a combination of electromechanical and hydraulic components. The design of the actuator is described herein, and results of an experimental characterization are provided that indicate that the actuator is capable of providing the functional capabilities required of an ankle prosthesis in a compact and lightweight package.

  4. HYDRAULICS, LOUISA COUNTY, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydraulic analysis for estimating flood stages for a flood insurance study. It...

  5. Hydraulic Hybrid Vehicles

    Science.gov (United States)

    EPA and the United Parcel Service (UPS) have developed a hydraulic hybrid delivery vehicle to explore and demonstrate the environmental benefits of the hydraulic hybrid for urban pick-up and delivery fleets.

  6. Nonmagnetic driver for piezoelectric actuators

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh

    2014-01-01

    Piezoelectric actuator drive aims to enable reliable motor performance in strong magnetic fields for magnetic res- onance imaging and computed tomography treatment tables. There are technical limitations in operation of these motors and drive systems related to magnetic interference. Piezoelectric...... actuators. Therefore, piezoelectric transformer-based power converters are used for driving piezoelectric actuator drive motor in the presence of high electromagnetic field....

  7. Overview on permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Permanent magnetic actuator (PMA), as a new electronic actuator of vacuum circuit breakers, certainly will be used to replace the traditional mechanical actuator. It has such advantages as simple structure, high reliability, free maintenance, and so on. This paper summarizes the development, structure, magnetic analysis, character analysis, and control strategy of PMA, and also predicts the future trend of PMA development

  8. Pneumatic Artificial Muscle Actuation and Modeling

    Science.gov (United States)

    Leephakpreeda, Thananchai; Wickramatunge, Kanchana C.

    2009-10-01

    A Pneumatic Artificial Muscle (PAM) yields a natural muscle-like actuator with a high force to weight ratio, a soft and flexible structure, and adaptable compliance for a humanoid robot, rehabilitation and prosthetic appliances to the disabled, etc. To obtain optimum design and usage, the mechanical behavior of the PAM need to be understood. In this study, observations of experimental results reveal an empirical model for relations of physical variables, contraction and air pressure within the PAM, as compared to mechanical characteristics, such as stiffness or/and pulling forces of the PAM available now in market.

  9. Towards a digital sound reconstruction MEMS device: Characterization of a single PZT based piezoelectric actuator

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2015-04-01

    In this paper we report the fabrication and characterization of a single piezoelectric actuator for digital sound reconstruction. This work is the first step towards the implementation of a true digital micro-loudspeaker by means of an array of acoustic actuators. These actuators consist of a flexible membrane fabricated using polyimide, which is actuated using a Lead-Zirconate-Titanate (PZT) piezoelectric ceramic layer working in the d31 actuation mode. The dimensions of the membrane are of 1mm diameter and 4μm in thickness, which is capable of being symmetrically actuated in both upward and downward directions, due to the back etch step releasing the membrane. Our electrical characterization shows an improvement in the polarization of the piezoelectric material after its final etch patterning step, and our mechanical characterization shows the natural modes of resonance of the stacked membrane. © 2015 IEEE.

  10. Double-section curvature tunable functional actuator with micromachined buckle and grid wire for electricity delivery

    Science.gov (United States)

    Feng, Guo-Hua; Hou, Sheng-You

    2015-09-01

    This paper presents an ionic polymer metal composite (IPMC)-driven tentacle-like biocompatible flexible actuator with double-section curvature tunability. This actuator, possessing an embedded electrical transmission ability that mimics skeletal muscle nerves in the human body, affords versatile device functions. Novel micromachined copper buckles and grid wires are fabricated and their superiority in electricity delivery and driving the IPMC component with less flexural rigidity is demonstrated. In addition, soft conductive wires realized on a polydimethylsiloxane structure function as electrical signal transmitters. A light-emitting diode integrated with the developed actuator offers directional guiding light ability while the actuator performs a snake-like motion. The electrical conductivity and Young’s modulus of the key actuator components are investigated, and flexural rigidity and dynamic behavior analyses of the actuator under electrical manipulation are elaborated.

  11. Design and dynamic evaluation for a linear ultrasonic stage using the thin-disc structure actuator.

    Science.gov (United States)

    Wen, Fuhliang; Yen, C-Y

    2007-12-01

    The design of a novel, single-axis ultrasonic actuating stage has been proposed. It consists of a movable plate, an edge-driving ultrasonic actuator as an actuating device, and a magnetic Magi encoder as a position sensor. The stage is impelled using a friction-contact mechanism by the ultrasonic actuator with long distance movement. Very high actuating and braking abilities are obtained. The stable and precise positioning control of the stage was achieved by using a neural-fuzzy controller. This simple and inexpensive structure of the single-axis stage demonstrates that the mechanical design of ultrasonic actuating concept could be done flexibly according to the requirements for various applications.

  12. Electromechanical flight control actuator

    Science.gov (United States)

    1979-01-01

    The feasibility of using an electromechanical actuator (EMA) as the primary flight control equipment in aerospace flight is examined. The EMA motor design is presented utilizing improved permanent magnet materials. The necessary equipment to complete a single channel EMA using the single channel power electronics breadboard is reported. The design and development of an improved rotor position sensor/tachometer is investigated.

  13. Airplane Actuation Trade Study

    Science.gov (United States)

    1983-01-01

    the electrical subsystem it is anticipated that 270 HVDC will not always be the most efficient power source. Lighting, instrumentation, avionics...sizing considerations all motor loads such as surface control actuators, fuel pumps, ECS fans and pumps, etc., are regarded as powered by 270 HVDC . All

  14. Shape Memory Alloy Actuator

    Science.gov (United States)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  15. A Magnetic Bead Actuator

    NARCIS (Netherlands)

    Derks, R.; Prins, M.W.J.; Wimberger-Friedl, R.

    2006-01-01

    Actuation principles of superparamagnetic beads applicable on biosensing (at single beads and chain orderning) are studied in this report. This research can be used to develop new techniques that are able to accelerate bio-assays. An experimental setup containing a sub-microliter fluid volume

  16. Piezoelectric actuator renaissance

    Science.gov (United States)

    Uchino, Kenji

    2015-03-01

    This paper resumes the content of the invited talk of the author, read at the occasion of the International Workshop on Relaxor Ferroelectrics, IWRF 14, held on October 12-16, 2014 in Stirin, Czech Republic. It reviews the recent advances in materials, designing concepts, and new applications of piezoelectric actuators, as well as the future perspectives of this area.

  17. Valve and Manifold considerations for Efficient Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Nørgård, Christian; Bech, Michael Møller;

    2016-01-01

    This paper seeks to shed light on the topic of design and sizing of switching valves and connecting manifolds found in large digital hydraulic motors, also known commercially as Digital Displacement Motors. These motors promise very high operation efficiencies with broad operation ranges, which set...... valves when considering also the manifold flow losses. A global optimization is conducted by use of the generalized differential evolution 3 algorithm, where the valve diameters, valve stroke lengths, actuator force capabilities and actuator timing signals are used as design variables. The results...

  18. Dynamic modeling of brushless dc motors for aerospace actuation

    Science.gov (United States)

    Demerdash, N. A.; Nehl, T. W.

    1980-11-01

    A discrete time model for simulation of the dynamics of samarium cobalt-type permanent magnet brushless dc machines is presented. The simulation model includes modeling of the interaction between these machines and their attached power conditioners. These are transistorized conditioner units. This model is part of an overall discrete-time analysis of the dynamic performance of electromechanical actuators, which was conducted as part of prototype development of such actuators studied and built for NASA-Johnson Space Center as a prospective alternative to hydraulic actuators presently used in shuttle orbiter applications. The resulting numerical simulations of the various machine and power conditioner current and voltage waveforms gave excellent correlation to the actual waveforms collected from actual hardware experimental testing. These results, numerical and experimental, are presented here for machine motoring, regeneration and dynamic braking modes. Application of the resulting model to the determination of machine current and torque profiles during closed-loop actuator operation were also analyzed and the results are given here. These results are given in light of an overall view of the actuator system components. The applicability of this method of analysis to design optimization and trouble-shooting in such prototype development is also discussed in light of the results at hand.

  19. Dynamic modeling of brushless dc motors for aerospace actuation

    Science.gov (United States)

    Demerdash, N. A.; Nehl, T. W.

    1980-01-01

    A discrete time model for simulation of the dynamics of samarium cobalt-type permanent magnet brushless dc machines is presented. The simulation model includes modeling of the interaction between these machines and their attached power conditioners. These are transistorized conditioner units. This model is part of an overall discrete-time analysis of the dynamic performance of electromechanical actuators, which was conducted as part of prototype development of such actuators studied and built for NASA-Johnson Space Center as a prospective alternative to hydraulic actuators presently used in shuttle orbiter applications. The resulting numerical simulations of the various machine and power conditioner current and voltage waveforms gave excellent correlation to the actual waveforms collected from actual hardware experimental testing. These results, numerical and experimental, are presented here for machine motoring, regeneration and dynamic braking modes. Application of the resulting model to the determination of machine current and torque profiles during closed-loop actuator operation were also analyzed and the results are given here. These results are given in light of an overall view of the actuator system components. The applicability of this method of analysis to design optimization and trouble-shooting in such prototype development is also discussed in light of the results at hand.

  20. A low order adaptive control scheme for hydraulic servo systems

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Pedersen, Henrik Clemmensen; Bech, Michael Møller;

    2015-01-01

    This paper deals with high-performance position control of hydraulics servo systems in general. The hydraulic servo system used is a two link robotic manipulator actuated by two hydraulic servo cylinders. A non-linear model of the hydraulic system and a Newton-Euler based model of the mechanical...... system were constructed and linearized. Controllers are implemented and tested on the manipulator. Pressure feedback was found to greatly improve system stability margins. Passive gain feedforward shows improved tracking performance for small changes in load pressure. For large changes in load pressure......, active gain feedforward shows a slightly improved performance. Computed-Torque Control shows better performance, but requires a well described system for best performance. A novel Adaptive Inverse Dynamics Controller was tested and the performance was found to be similar to that of Computed...

  1. Flexible supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Shan Shi; Chengjun Xu; Cheng Yang; Jia Li; Hongda Du; Baohua Li; Feiyu Kang

    2013-01-01

    Flexible supercapacitors show a great potential for applications in wearable,miniaturized,portable,largescale transparent and flexible consumer electronics due to their significant,inherent advantages,such as being flexible,lightweight,low cost and environmentally friendly in comparison with the current energy storage devices.In this report,recent progress on flexible supercapacitors,flexible electrodes and electrolytes is reviewed.In addition,the future challenges and opportunities are discussed.

  2. Advancements in Actuated Musical Instruments

    DEFF Research Database (Denmark)

    Overholt, Daniel; Berdahl, Edgar; Hamilton, Robert

    2011-01-01

    This article presents recent developments in actuated musical instruments created by the authors, who also describe an ecosystemic model of actuated performance activities that blur traditional boundaries between the physical and virtual elements of musical interfaces. Actuated musical instrument...... that these instruments enable. We look at some of the conceptual and perceptual issues introduced by actuated musical instruments, and finally we propose some directions in which such research may be headed in the future.......This article presents recent developments in actuated musical instruments created by the authors, who also describe an ecosystemic model of actuated performance activities that blur traditional boundaries between the physical and virtual elements of musical interfaces. Actuated musical instruments...... are physical instruments that have been endowed with virtual qualities controlled by a computer in real-time but which are nevertheless tangible. These instruments provide intuitive and engaging new forms of interaction. They are different from traditional (acoustic) and fully automated (robotic) instruments...

  3. Design and Evaluation of a Direct Drive Valve Actuated by Piezostack Actuator

    Directory of Open Access Journals (Sweden)

    Juncheol Jeon

    2013-01-01

    Full Text Available This paper presents performance characteristics of a new type of direct drive valve (DDV system driven by a piezostack actuator. The flexible beam mechanism is employed to amplify the output displacement from the piezostack actuator. After describing the operational principle of the proposed piezo DDV system, the governing equation of the whole piezo DDV system is then obtained by integrating the equations of the valve components. Based on the proposed model, significant structural components of the piezo DDV system are designed in order to achieve operational requirements (operating frequency: over 100 Hz; flow rate: 20 liter/Min.. An optimal design method is proposed for obtaining the geometry of the flexible beam mechanism by considering spool displacement, required operating frequency, and available space of the valve. After deciding the specific geometric dimensions of the piezo DDV system, a PID control algorithm is designed to enforce the spool position to the desired position trajectories by activating the piezostack actuator. Characteristics and control performances of the proposed piezo DDV system are evaluated using the MATLAB Simulink.

  4. Macro Fiber Piezocomposite Actuator Poling Study

    Science.gov (United States)

    Werlink, Rudy J.; Bryant, Robert G.; Manos, Dennis

    2002-01-01

    The performance and advantages of Piezocomposite Actuators are to provide a low cost, in-situ actuator/sensor that is flexible, low profile and high strain per volt performance in the same plane of poled voltage. This paper extends reported data for the performance of these Macrofiber Composite (MFC) Actuators to include 4 progressively narrower Intedigitized electrode configurations with several line widths and spacing ratios. Data is reported for max free strain, average strain per applied volt, poling (alignment of the electric dipoles of the PZT ceramic) voltage vs. strain and capacitance, time to poling voltage 95% saturation. The output strain per volt progressively increases as electrode spacing decreases, with saturation occurring at lower poling voltages. The narrowest spacing ratio becomes prone to voltage breakdown or short circuits limiting the spacing width with current fabrication methods. The capacitance generally increases with increasing poling voltage level but has high sensitivity to factors such as temperature, moisture and time from poling which limit its usefulness as a simple indicator. The total time of applied poling voltage to saturate or fully line up the dipoles in the piezoceramic was generally on the order of 5-20 seconds. Less sensitivity to poling due to the applied rate of voltage increase over a 25 to 500 volt/second rate range was observed.

  5. Shape-memory-actuated compliant control surface

    Science.gov (United States)

    Maclean, Brian J.; Carpenter, Bernie F.; Draper, Jerry L.; Misra, Mohan S.

    1993-09-01

    Advanced submarine stern configurations require a variety of control surfaces to actively manage aftbody boundary layer flow, vorticity, propulsor inflow and intrapropulsor flow, as well as vehicle attitude. Two necessary attributes of advanced control surface designs include (1) integrated actuation to provide placement flexibility at remote locations with minimal structural interfacing and control interconnects, and (2) improved lift efficiency and flow using variable or adaptive camber control. To demonstrate these attributes, a shape memory alloy (SMA) actuated compliant control fin (CCF) with a planform area of 620 sq. cm was developed for evaluation as rudder and sternplane appendages on a radio control submarine model at velocities up to 5.1 m/s (Reynolds No. approximately equals 1,000,000) and up to 0.2 Hz full cycle actuation. A completely fixed root design was developed to reduce turbulence at the hull/fine interface, with compliant deformation of the foil to improve flow characteristics over the baseline full-flying and trailing-edge-flap designs.

  6. RECURSIVE DYNAMICS AND REAL TIME SIMULATION OF UNDER-ACTUATED FLEXIBLE SPACE ROBOTS SYSTEM%欠驱动空间柔性机器人动力学建模与实时仿真

    Institute of Scientific and Technical Information of China (English)

    田富洋; 吴洪涛; 王冉冉; 李法德

    2012-01-01

    In order to improve the modeling efficiency for the computational dynamics of the open loop flexible robot, the generalized hybrid recursive dynamics base on the Spatial Operator Algebra (SOA) theory was presented. The generalized flexible robot was described in according to the type of the joint (active or passive). The generalized articulated inertia-matrix, the residual forces and the generalized acceleration and torque were computed through twice tip-to-base recursion and once base-to-tip recursion. At last the O(n) hybrid dynamics was gained. Then the real time solver for the differential-algebra equation was studied based on the linear multi-step method in this paper. Simulations results show that the dynamic modeling and fast integration techniques proposed in this paper are very useful.%研究了在轨服务欠驱动空间柔性机器人的广义递推高效动力学算法.根据系统中铰的驱动情况分别对铰链定义为主动铰和被动铰,通过判断铰链的类型分别按照两次从系统的顶端到基座的顺序、一次从基座到顶端的顺序进行了系统铰接体惯量的递推、系统冗余力的递推和广义加速度和广义主动力的递推.通过上述3种方式的递推过程建立了空间机器人广义递推动力学模型,实现了高效率0∽)次的计算效率.然后采用线性多步积分算法,对所建立的微分一代数方程进行了快速的数值求解.最后通过软件编制仿真验证了本研究内容的正确性和高效性.

  7. A study on the effect of surface topography on the actuation performance of stacked-rolled dielectric electro active polymer actuator

    Science.gov (United States)

    Sait, Usha; Muthuswamy, Sreekumar

    2016-05-01

    Dielectric electro active polymer (DEAP) is a suitable actuator material that finds wide applications in the field of robotics and medical areas. This material is highly controllable, flexible, and capable of developing large strain. The influence of geometrical behavior becomes critical when the material is used as miniaturized actuation devices in robotic applications. The present work focuses on the effect of surface topography on the performance of flat (single sheet) and stacked-rolled DEAP actuators. The non-active areas in the form of elliptical spots that affect the performance of the actuator are identified using scanning electron microscope (SEM) and energy dissipated X-ray (EDX) experiments. Performance of DEAP actuation is critically evaluated, compared, and presented with analytical and experimental results.

  8. Aircraft Hydraulic System Leakage Detection and Servicing Recommendations Method

    Science.gov (United States)

    2014-10-02

    accumulators, filters, and consumers, that include all the actuators connected to the hydraulic power such as flight controls , brake and landing...Conference, October 4-8 Calgary, Alberta, Canada. Merrit, H. E., (1967), Hydraulic Control Systems. New York: John Willey & Sons. Vianna, W. O. L...2008), Modelagem e Análise do Sistema Hidráulico de uma Aeronave Comercial Regional. M.Sc. Thesis. Instituto Tecnológico de Aeronáutica, São José

  9. Experimental evaluation of control strategies for hydraulic servo robot

    DEFF Research Database (Denmark)

    Bech, Michael Møller; Andersen, Torben Ole; Pedersen, Henrik C.

    2013-01-01

    In this paper different linear and non-linear controllers applied to a hydraulically driven servo robot are evaluated and validated. The task is to make the actuators of the manipulator track a position reference with minimum error. Hydraulic systems are intrinsically non-linear and using linear...... control techniques typically results in conservatively dimensioned controllers to obtain stable performance. Non-linear control techniques have the potential of overcoming these problems and in this paper the focus is on applying simple nonlinear robust and adaptive controllers feasible for implementation...... in industrial servo drives. The different controllers are compared and evaluated from simulation and experimental results....

  10. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  11. Design optimization of harvester head and actuation system of forest harvester

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Hansen, Michael R.; Mouritsen, Ole Ø.

    2005-01-01

    This paper is on the analysis and subsequent efficiency optimization of a forrest harvester. As basis for the optimization the existing machine has undergone substantial experimental testing with a view to determine the loading that the harvester head is subjected to and also the corresponding ef...... efficiency of the hydraulic actuation system during a typical working cycle....

  12. Scissor thrust valve actuator

    Science.gov (United States)

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  13. Active Polymer Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2010-01-01

    Full Text Available Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a wormlike motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.

  14. Dissolution actuated sample container

    Science.gov (United States)

    Nance, Thomas A.; McCoy, Frank T.

    2013-03-26

    A sample collection vial and process of using a vial is provided. The sample collection vial has an opening secured by a dissolvable plug. When dissolved, liquids may enter into the interior of the collection vial passing along one or more edges of a dissolvable blocking member. As the blocking member is dissolved, a spring actuated closure is directed towards the opening of the vial which, when engaged, secures the vial contents against loss or contamination.

  15. Active Polymer Gel Actuators

    OpenAIRE

    Shuji Hashimoto; Ryo Yoshida; Yusuke Hara; Shingo Maeda

    2010-01-01

    Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of he...

  16. Shape memory alloy actuator

    Science.gov (United States)

    Varma, Venugopal K.

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  17. Experimental Validation of Mathematical Framework for Fast Switching Valves used in Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller;

    2015-01-01

    A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based...... on an elaborate optimization method the valve is designed to maximize the efficiency of a digital hydraulic motor targeted to a wind turbine transmission system. The optimisation method comprises a mathematical framework which predicts a valve switching time of approximately 1 ms with a peak actuator input power...

  18. FRF based position controller design through system identification for A hydraulic cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Hyoung Kyu; Kim, Dong Hwan [Dept. of Mechanical Design and Robot Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of); Park, Jong Won [Reliability Assessment Center, Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2015-11-15

    In this study, we have focused on the design of a controller and an operating program for the operation of the hydraulic actuators used in a shaker. To control the motion of the shaker accurately, the position of each hydraulic cylinder should be controlled precisely even under an uncertain environment. For this purpose, we have suggested a control algorithm using an FRF (frequency response function) based control which senses the behavior of the actuator in advance, calculates a transfer function through the system identification method, and provides the final control input. The experimental results on the performance of this system were compared with that of a simple PID control algorithm.

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

    OpenAIRE

    Juntao Fei; Yunmei Fang; Chunyan Yan

    2010-01-01

    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...

  20. Control method and system for hydraulic machines employing a dynamic joint motion model

    Science.gov (United States)

    Danko, George

    2011-11-22

    A control method and system for controlling a hydraulically actuated mechanical arm to perform a task, the mechanical arm optionally being a hydraulically actuated excavator arm. The method can include determining a dynamic model of the motion of the hydraulic arm for each hydraulic arm link by relating the input signal vector for each respective link to the output signal vector for the same link. Also the method can include determining an error signal for each link as the weighted sum of the differences between a measured position and a reference position and between the time derivatives of the measured position and the time derivatives of the reference position for each respective link. The weights used in the determination of the error signal can be determined from the constant coefficients of the dynamic model. The error signal can be applied in a closed negative feedback control loop to diminish or eliminate the error signal for each respective link.

  1. Compact, Low-Force, Low-Noise Linear Actuator

    Science.gov (United States)

    Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph

    2012-01-01

    Actuators are critical to all the robotic and manipulation mechanisms that are used in current and future NASA missions, and are also needed for many other industrial, aeronautical, and space activities. There are many types of actuators that were designed to operate as linear or rotary motors, but there is still a need for low-force, low-noise linear actuators for specialized applications, and the disclosed mechanism addresses this need. A simpler implementation of a rotary actuator was developed where the end effector controls the motion of a brush for cleaning a thermal sensor. The mechanism uses a SMA (shape-memory alloy) wire for low force, and low noise. The linear implementation of the actuator incorporates a set of springs and mechanical hard-stops for resetting and fault tolerance to mechanical resistance. The actuator can be designed to work in a pull or push mode, or both. Depending on the volume envelope criteria, the actuator can be configured for scaling its volume down to 4x2x1 cu cm. The actuator design has an inherent fault tolerance to mechanical resistance. The actuator has the flexibility of being designed for both linear and rotary motion. A specific configuration was designed and analyzed where fault-tolerant features have been implemented. In this configuration, an externally applied force larger than the design force does not damage the active components of the actuator. The actuator housing can be configured and produced using cost-effective methods such as injection molding, or alternatively, its components can be mounted directly on a small circuit board. The actuator is driven by a SMA -NiTi as a primary active element, and it requires energy on the order of 20 Ws(J) per cycle. Electrical connections to points A and B are used to apply electrical power in the resistive NiTi wire, causing a phase change that contracts the wire on the order of 5%. The actuation period is of the order of a second for generating the stroke, and 4 to 10

  2. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    Science.gov (United States)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  3. System and method for controlling hydraulic pressure in electro-hydraulic valve actuation systems

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, Daniel G; Marriott, Craig D; Cowgill, Joel; Wiles, Matthew A; Patton, Kenneth James

    2014-09-23

    A control system for an engine includes a first lift control module and a second lift control module. The first lift control module increases lift of M valves of the engine to a predetermined valve lift during a period before disabling or re-enabling N valves of the engine. The second lift control module decreases the lift of the M valves to a desired valve lift during a period after enabling or re-enabling the N valves of the engine, wherein N and M are integers greater than or equal to one.

  4. Strategic flexibility

    OpenAIRE

    Kim, KiHyung

    2014-01-01

    A flexible system is defined as one that can change the entity's stance, capability or status reacting to a change of the entity's environment. Flexibility has gathered the attention of academic researchers and industry practitioners as an efficient approach to cope with today's volatile environment. As the environments become more unpredictable and volatile, it is imperative for a flexible system to respond quickly to a change in its circumstance. How much flexibility is embedded into the sy...

  5. Self-Latching Piezocomposite Actuator

    Science.gov (United States)

    Wilkie, William K. (Inventor); Bryant, Robert G. (Inventor); Lynch, Christopher S. (Inventor)

    2017-01-01

    A self-latching piezocomposite actuator includes a plurality of shape memory ceramic fibers. The actuator can be latched by applying an electrical field to the shape memory ceramic fibers. The actuator remains in a latched state/shape after the electrical field is no longer present. A reverse polarity electric field may be applied to reset the actuator to its unlatched state/shape. Applied electric fields may be utilized to provide a plurality of latch states between the latched and unlatched states of the actuator. The self-latching piezocomposite actuator can be used for active/adaptive airfoils having variable camber, trim tabs, active/deformable engine inlets, adaptive or adjustable vortex generators, active optical components such as mirrors that change shapes, and other morphing structures.

  6. Flexible Ablators

    Science.gov (United States)

    Stackpoole, Margaret M. (Inventor); Ghandehari, Ehson M. (Inventor); Thornton, Jeremy J. (Inventor); Covington, Melmoth Alan (Inventor)

    2017-01-01

    A low-density article comprising a flexible substrate and a pyrolizable material impregnated therein, methods of preparing, and devices using the article are disclosed. The pyrolizable material pyrolizes above 350 C and does not flow at temperatures below the pyrolysis temperature. The low-density article remains flexible after impregnation and continues to remain flexible when the pyrolizable material is fully pyrolized.

  7. Muscular MEMS—the engineering of liquid crystal elastomer actuators

    Science.gov (United States)

    Petsch, S.; Khatri, B.; Schuhladen, S.; Köbele, L.; Rix, R.; Zentel, R.; Zappe, H.

    2016-08-01

    A new class of soft-matter actuator, the liquid crystal elastomer (LCE), shows promise for application in a wide variety of mechanical microsystems. Frequently referred to as an ‘artificial muscle’, this family of materials exhibits large actuation stroke and generates considerable force, in a compact form which may easily be combined with the structures and devices commonly used in microsystems and MEMS. We show here how standard microfabrication techniques may be used to integrate LCEs into mechanical microsystems and present an in-depth analysis of their mechanical and actuation properties. Using an example from micro-optics and optical MEMS, we demonstrate that their performance and flexibility allows realization of entirely new types of tunable optical functionality.

  8. Design and control of hybrid actuation lower limb exoskeleton

    Directory of Open Access Journals (Sweden)

    Hipolito Aguilar-Sierra

    2015-06-01

    Full Text Available In this article, two types of actuators are applied for a lower limb exoskeleton. They are DC motors with the harmonic drive and the pneumatic artificial muscles. This combination takes advantages of both the harmonic drive and the pneumatic artificial muscle. It provides both high accuracy position control and high ratio of strength and weight. The shortcomings of the two actuators are overcome by the hybrid actuation, for example, low control accuracy and modeling difficult of pneumatic artificial muscle, compactness, and structural flexibility of DC motors. The design and modeling processes are discussed to show the proposed exoskeleton can increase the strength of human lower limbs. Experiments and analysis of the exoskeleton are given to evaluate the effectiveness of the design and modeling.

  9. Development of soft robots using dielectric elastomer actuators

    Science.gov (United States)

    Godaba, Hareesh; Wang, Yuzhe; Cao, Jiawei; Zhu, Jian

    2016-04-01

    Soft robots are gaining in popularity due to their unique attributes such as low weight, compliance, flexibility and diverse range in motion types. This paper illustrates soft robots and actuators which are developed using dielectric elastomer. These developments include a jellyfish robot, a worm like robot and artificial muscle actuators for jaw movement in a robotic skull. The jellyfish robot which employs a bulged dielectric elastomer membrane has been demonstrated too generate thrust and buoyant forces and can move effectively in water. The artificial muscle for jaw movement employs a pure shear configuration and has been shown to closely mimic the jaw motion while chewing or singing a song. Thee inchworm robot, powered by dielectric elastomer actuator can demonstrate stable movement in one-direction.

  10. Fault-tolerant rotary actuator

    Science.gov (United States)

    Tesar, Delbert

    2006-10-17

    A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

  11. Balancing of Rigid and Flexible Rotors

    Science.gov (United States)

    1986-01-01

    converters Turbine wheels Turbinas (steam, gas , hydraulic), high speed > 10,000 rpm Turbines (steam, gas , hydraulic), medium speed 1000-10,000 rpm...MOUNTED ON CASINGD AI GA - + SIGNALS PROCESSED BY TRACKING FILTERS AND TIME-AVERAGED TO IDENTIFY PRINCIPAL FREQUENCY COMPONENTS Fig. 1.10, Noncontactlng...balanrcng of gas -turbine engines; by Little [121, whose thesis on flexible-rotor balancing contains selected refer- ences on this subject; and by Kendig

  12. A Hydraulic Blowdown Servo System For Launch Vehicle

    Science.gov (United States)

    Chen, Anping; Deng, Tao

    2016-07-01

    This paper introduced a hydraulic blowdown servo system developed for a solid launch vehicle of the family of Chinese Long March Vehicles. It's the thrust vector control (TVC) system for the first stage. This system is a cold gas blowdown hydraulic servo system and consist of gas vessel, hydraulic reservoir, servo actuator, digital control unit (DCU), electric explosion valve, and pressure regulator etc. A brief description of the main assemblies and characteristics follows. a) Gas vessel is a resin/carbon fiber composite over wrapped pressure vessel with a titanium liner, The volume of the vessel is about 30 liters. b) Hydraulic reservoir is a titanium alloy piston type reservoir with a magnetostrictive sensor as the fluid level indicator. The volume of the reservoir is about 30 liters. c) Servo actuator is a equal area linear piston actuator with a 2-stage low null leakage servo valve and a linear variable differential transducer (LVDT) feedback the piston position, Its stall force is about 120kN. d) Digital control unit (DCU) is a compact digital controller based on digital signal processor (DSP), and deployed dual redundant 1553B digital busses to communicate with the on board computer. e) Electric explosion valve is a normally closed valve to confine the high pressure helium gas. f) Pressure regulator is a spring-loaded poppet pressure valve, and regulates the gas pressure from about 60MPa to about 24MPa. g) The whole system is mounted in the aft skirt of the vehicle. h) This system delivers approximately 40kW hydraulic power, by contrast, the total mass is less than 190kg. the power mass ratio is about 0.21. Have finished the development and the system test. Bench and motor static firing tests verified that all of the performances have met the design requirements. This servo system is complaint to use of the solid launch vehicle.

  13. Flexible Software for Flexible Scheduling

    Science.gov (United States)

    Economou, Frossie; Jenness, Tim; Tilanus, Remo P. J.; Hirst, Paul; Adamson, Andy J.; Rippa, Mathew; Delorey, Kynan K.; Isaak, Kate G.

    The JAC Observation Management Project (OMP) provides software for the James Clerk Maxwell (JCMT) and the United Kingdom Infrared (UKIRT) telescopes that manages the life-cycle of flexibly scheduled observations. Its aim is to increase observatory efficiency under flexible (queue) scheduled observing, without depriving the principal investigator (PI) of the flexibility associated with classical scheduling.

  14. Robotic Arm Actuated by Electroactie Polymers

    Science.gov (United States)

    Bar-Cohen, Y.; Xue, T.; Shaninpoor, M.; Simpson, J. O.; Smith, J.

    1998-01-01

    Actuators are used for many planetary and space applications. To meet the NASA goal to reduce the actuators size, mass, cost and power consumption, electroactie polymers (EAP) are being developed to induce large bending and longitudinal actuation strains.

  15. Piezoelectric actuated gimbal

    Science.gov (United States)

    Tschaggeny, Charles W.; Jones, Warren F.; Bamberg, Eberhard

    2011-09-13

    A gimbal is described and which includes a fixed base member defining an axis of rotation; a second member concentrically oriented relative to the axis of rotation; a linear actuator oriented in immediate, adjoining force transmitting relation relative to the base member or to the second member, and which applies force along a linear axis which is tangential to the axis of rotation so as to cause the second member to rotate coaxially relative to the fixed base member; and an object of interest mounted to the second member such that the object of interest is selectively moved relative to the base member about the axis of rotation.

  16. Pneumatically actuated micropipetting device

    Science.gov (United States)

    Szita, Nicolas; Buser, Rudolf A.

    1998-03-01

    We have realized a valveless micropipetting device with an integrated sensor which can aspirate and dispense liquid volumes without any valves, hence without any reflow or dead volume. With an external pneumatic actuation, we have demonstrated aspirating and dispensing from 190nl of 6 (mu) l of water. Measurements showed a standard deviation of down to 1 percent. An integrated capacitive sensor will allow monitoring of the pressure throughout the pipetting process and detect malfunctions, e.g. clotting of the pipetting tip. It is our intention to use this demonstrated precise aspiration mechanism in combination with a micromachined reaction chamber and a miniaturized optical analysis system.

  17. Reversible Self-Actuated Thermo-Responsive Pore Membrane

    Science.gov (United States)

    Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P.

    2016-12-01

    Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of pore actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated pore membrane that achieves opening and closing of pores. The reversible, self-actuated thermo-responsive pore membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional pore array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that pore opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the pore structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive pore membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.

  18. Reversible Self-Actuated Thermo-Responsive Pore Membrane.

    Science.gov (United States)

    Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P

    2016-12-19

    Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of pore actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated pore membrane that achieves opening and closing of pores. The reversible, self-actuated thermo-responsive pore membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional pore array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that pore opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the pore structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive pore membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.

  19. Ultra-compliant liquid metal electrodes with in-plane self-healing capability for dielectric elastomer actuators

    Science.gov (United States)

    Liu, Yang; Gao, Meng; Mei, Shengfu; Han, Yanting; Liu, Jing

    2013-08-01

    The method of directly printing liquid metal films as highly conductive and super compliant electrodes for dielectric elastomer actuator (DEA) was proposed and experimentally demonstrated with working mechanisms interpreted. Such soft electrodes enable DE film to approach its maximum strain and stress at relatively low voltages. Further, its unique capability of achieving two-dimensional in-plane self-healing by merely actuating the DEA was disclosed, which would allow actuators more tolerant to fault and resilient to abusive environments. This high performance actuator has important value in a wide spectrum of situations ranging from artificial muscle, flexible electronics to smart clothing etc.

  20. Large displacement bi-directional out-of-plane Lorentz actuator array for surface manipulation

    Science.gov (United States)

    Park, Byoungyoul; Afsharipour, Elnaz; Chrusch, Dwayne; Shafai, Cyrus; Andersen, David; Burley, Greg

    2017-08-01

    This paper presents a large displacement out-of-plane Lorentz actuator array for surface manipulation. Actuators are formed from single crystal silicon flexible serpentine springs on either side of a rigid crossbar containing a narrow contact pillar. A rigid mounting rail system was employed to enable a 5  ×  5 array, which offers scalability of the array size. Analytical and finite element models were used to optimize actuator design. Individual actuators were tested to show linear deflection response of  ±150 µm motion, using a  ±14.7 mA current in the presence of a 0.48 T magnetic field. This actuator array is suitable for various 2D surface modification applications due to its large deformation with low current and temperature of operation, and narrow contact area to a target surface.

  1. Study on Optimal Placement of Piezoelectric Actuators for a Whole Spacecraft Vibration Isolator

    Directory of Open Access Journals (Sweden)

    Liu Fang

    2012-04-01

    Full Text Available Position of actuators plays an important role in active vibration control, which affects not only the performance of vibration control but also the stability of the whole system, especially for flexible structures. In this paper, dynamic sensitivity analysis method was used to derive an optimization criterion for Piezoelectric Stack Actuator (PSA, this criterion was only related to the dynamic characteristics of the structure itself and the features of disturbances, but was not affected by initial conditions and control methods. Then by using this criterion, optimal placement of the piezoelectric actuator of a Whole-Spacecraft Vibration Isolator (WSVI was studied, and vibration control effect of random position and optimal position was compared; simulation results verified the validity of the criteria, and showed that the optimized location of actuator could greatly enhance the actuation efficiency and vibration control effect.

  2. Serpentine Geometry Plasma Actuators for Flow Control

    Science.gov (United States)

    2013-08-23

    electrical power is supplied to them. As a method of introducing perturbations for low speed flow control, dielectric barrier discharge ( DBD ) actuators...SERPENTINE GEOMETRY DBD ACTUATORS DBD actuators are devices consisting of two asymmetri- cally placed actuators separated by a dielectric material and exposed...parameters can be found in Table I. The effects of plasma actuation are FIG. 1. (a) Schematic of DBD plasma actuator and the generated body force. (b

  3. Placement optimization of actuators and sensors for gyroelastic body

    Directory of Open Access Journals (Sweden)

    Quan Hu

    2015-03-01

    Full Text Available Gyroelastic body refers to a flexible structure with a distribution of stored angular momentum provided by fly wheels or control moment gyroscopes. The angular momentum devices can exert active torques to the structure for vibration suppression or shape control. This article mainly focuses on the placement optimization issue of the actuators and sensors on the gyroelastic body. The control moment gyroscopes and angular rate sensors are adopted as actuators and sensors, respectively. The equations of motion of the gyroelastic body incorporating the detailed actuator dynamics are linearized to a loosely coupled state-space model. Two optimization approaches are developed for both constrained and unconstrained gyroelastic bodies. The first is based on the controllability and observability matrices of the system. It is only applicable to the collocated actuator and sensor pairs. The second criterion is formulated from the concept of controllable and observable subspaces. It is capable of handling the cases of both collocated and noncollocated actuator and sensor pairs. The illustrative examples of a cantilevered beam and an unconstrained plate demonstrate the clear physical meaning and rationality of the two proposed methods.

  4. Analytical and experimental investigation of flutter suppression by piezoelectric actuation

    Science.gov (United States)

    Heeg, Jennifer

    1993-01-01

    The objective of this research was to analytically and experimentally study the capabilities of piezoelectric plate actuators for suppressing flutter. Piezoelectric materials are characterized by their ability to produce voltage when subjected to a mechanical strain. The converse piezoelectric effect can be utilized to actuate a structure by applying a voltage. For this investigation, a two-degree-of-freedom wind tunnel model was designed, analyzed, and tested. The model consisted of a rigid wing and a flexible mount system that permitted a translational and a rotational degree of freedom. The model was designed such that flutter was encountered within the testing envelope of the wind tunnel. Actuators made of piezoelectric material were affixed to leaf springs of the mount system. Command signals, applied to the piezoelectric actuators, exerted control over the damping and stiffness properties. A mathematical aeroservoelastic model was constructed by using finite element methods, laminated plate theory, and aeroelastic analysis tools. Plant characteristics were determined from this model and verified by open loop experimental tests. A flutter suppression control law was designed and implemented on a digital control computer. Closed loop flutter testing was conducted. The experimental results represent the first time that adaptive materials have been used to actively suppress flutter. They demonstrate that small, carefully placed actuating plates can be used effectively to control aeroelastic response.

  5. Soft Pneumatic Bending Actuator with Integrated Carbon Nanotube Displacement Sensor

    Directory of Open Access Journals (Sweden)

    Tim Giffney

    2016-02-01

    Full Text Available The excellent compliance and large range of motion of soft actuators controlled by fluid pressure has lead to strong interest in applying devices of this type for biomimetic and human-robot interaction applications. However, in contrast to soft actuators fabricated from stretchable silicone materials, conventional technologies for position sensing are typically rigid or bulky and are not ideal for integration into soft robotic devices. Therefore, in order to facilitate the use of soft pneumatic actuators in applications where position sensing or closed loop control is required, a soft pneumatic bending actuator with an integrated carbon nanotube position sensor has been developed. The integrated carbon nanotube position sensor presented in this work is flexible and well suited to measuring the large displacements frequently encountered in soft robotics. The sensor is produced by a simple soft lithography process during the fabrication of the soft pneumatic actuator, with a greater than 30% resistance change between the relaxed state and the maximum displacement position. It is anticipated that integrated resistive position sensors using a similar design will be useful in a wide range of soft robotic systems.

  6. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  7. IT-Tools Concept for Simulation and Design of Water Hydraulic Mechatronic Test Facilities for Motion Control and Operation in Environmentally Sensitive Application Areas

    DEFF Research Database (Denmark)

    Conrad, Finn; Pobedza, J.; Sobczyk, A.

    2004-01-01

    This paper presents a proposed IT-Tools concept for modeling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The designed test rigs have tap water hydraulic components of the Danfoss Nessie® product family and equipped...

  8. Handbook of hydraulic fluid technology

    CERN Document Server

    Totten, George E

    2011-01-01

    ""The Handbook of Hydraulic Fluid Technology"" serves as the foremost resource for designing hydraulic systems and for selecting hydraulic fluids used in engineering applications. Featuring new illustrations, data tables, as well as practical examples, this second edition is updated with essential information on the latest hydraulic fluids and testing methods. The detailed text facilitates unparalleled understanding of the total hydraulic system, including important hardware, fluid properties, and hydraulic lubricants. Written by worldwide experts, the book also offers a rigorous overview of h

  9. Electromagnetic actuation in MEMS switches

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de; Mátéfi-Tempfli, Mária; Chemnitz, Steffen

    . Electromagnetic actuation is a very promising approach to operate such MEMS and Power MEMS devices, due to the long range, reproducible and strong forces generated by this method, among other advantages. However, the use of electromagnetic actuation in such devices requires the use of thick magnetic films, which...

  10. Polypyrrole Actuators for Tremor Suppression

    DEFF Research Database (Denmark)

    Skaarup, Steen; Mogensen, Naja; Bay, Lasse

    2003-01-01

    exemplify 'soft actuator' technology that may be especially suitable for use in conjunction with human limbs. The electrochemical and mechanical properties of polypyrrole dodecyl benzene sulphonate actuator films have been studied with this application in mind. The results show that the time constants...

  11. Rotary actuator for space applications

    Science.gov (United States)

    Andión, J. A.; Burgui, C.; Migliorero, G.

    2005-07-01

    SENER is developing a rotary actuator for space applications. The activity, partially funded under ESA GSTP contract, aims at the design, development and performance testing of an innovative rotary actuator concept for space applications. An engineering model has been manufactured and has been tested to demonstrate the compliance with the requirements specification.

  12. Bi-stable optical actuator

    Science.gov (United States)

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  13. Hybrid active vibration control of rotorbearing systems using piezoelectric actuators

    Science.gov (United States)

    Palazzolo, A. B.; Jagannathan, S.; Kascak, A. F.; Montague, G. T.; Kiraly, L. J.

    1993-01-01

    The vibrations of a flexible rotor are controlled using piezoelectric actuators. The controller includes active analog components and a hybrid interface with a digital computer. The computer utilizes a grid search algorithm to select feedback gains that minimize a vibration norm at a specific operating speed. These gains are then downloaded as active stillnesses and dampings with a linear fit throughout the operating speed range to obtain a very effective vibration control.

  14. Discrete piezoelectric sensors and actuators for active control of two-dimensional spacecraft components

    Science.gov (United States)

    Bayer, Janice I.; Varadan, V. V.; Varadan, V. K.

    1991-01-01

    This paper describes research into the use of discrete piezoelectric sensors and actuators for active modal control of flexible two-dimensional structures such as might be used as components for spacecraft. A dynamic coupling term is defined between the sensor/actuator and the structure in terms of structural model shapes, location and piezoelectric behavior. The relative size of the coupling term determines sensor/actuator placement. Results are shown for a clamped square plate and for a large antenna. An experiment was performed on a thin foot-square plate clamped on all sides. Sizable vibration control was achieved for first, second/third (degenerate) and fourth modes.

  15. Forgiveness Flexibility

    Directory of Open Access Journals (Sweden)

    Tuğba Seda Çolak

    2016-01-01

    Full Text Available Forgiveness flexibility is the skill to minimize the negative effect of an event by using cognitive, affective and behavioral skills while taking a stand at the end of an injurious process. A number of studies were conducted to test the flexibility of the structure of forgiveness. The theoretical structure, structural validity and the confirmatory factor analysis supported the theoretical structure of forgiveness flexibility. The criterion validity evaluated in similar manners was found high. Forgiveness flexibility designed as a three dimensional structure and its sub-dimensions was confirmed theoretically as the recognition of forgivenessand the internalization of forgiveness through insight and its practice.

  16. Evaluation of Linear and Non-Linear Control Schemes Applied to a Hydraulic Servo System

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Hansen, Michael Rygaard; Pedersen, Henrik Clemmensen

    2005-01-01

    Due to the innovation of low-cost electronics such as sensors, microcontrollers etc., the focus on highperformance motion control is increasing. This work focuses on position control of single-input single-output hydraulic servo-systems in general. A hydraulically actuated robotic manipulator...... is used as test facility acting as load for the hydraulic servo system. An experimentally verified non-linear model of the complete system has been developed and used to design a series of both linear and non-linear control schemes. The controllers from each category are compared with respect to design...

  17. Powered orthosis and attachable power-assist device with Hydraulic Bilateral Servo System.

    Science.gov (United States)

    Ohnishi, Kengo; Saito, Yukio; Oshima, Toru; Higashihara, Takanori

    2013-01-01

    This paper discusses the developments and control strategies of exoskeleton-type robot systems for the application of an upper limb powered orthosis and an attachable power-assist device for care-givers. Hydraulic Bilateral Servo System, which consist of a computer controlled motor, parallel connected hydraulic actuators, position sensors, and pressure sensors, are installed in the system to derive the joint motion of the exoskeleton arm. The types of hydraulic component structure and the control strategy are discussed in relation to the design philosophy and target joints motions.

  18. DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations.

  19. Conflicting flexibility

    NARCIS (Netherlands)

    De Jong, P.; Schaap, A.

    2011-01-01

    New buildings are designed for first users. For a sustainable approach there are many advantages in designing in flexibility and adjustability in order to enable and facilitate the other sequential users. For the first investor this flexibility is translated into improved exit values due to

  20. The Actuated Guitar

    DEFF Research Database (Denmark)

    Larsen, Jeppe Veirum; Overholt, Daniel; Moeslund, Thomas B.

    2013-01-01

    electrical gui- tar, sensors to capture the rhythmic motion of alternative fully functioning limbs, such as a foot, knee or the head, and a motorized fader moving a pick back and forth across the strings. A microcontroller is utilized for pro- cessing sensor data, which allows flexible mapping of user input...

  1. Experimental Validation of Mathematical Framework for Fast Switching Valves used in Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller

    2015-01-01

    A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based on an el......A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based...... of 10 kW during switching (mean of approximately 250 W) and a pressure loss below 0.5 bar at 600 l/min. The main goal of this article is validate parts of the mathematical framework based on a series of experiments. Furthermore, this article aims to document the experience gained from the experimental...... work and to study and assess a moving coil actuators suitability for the application....

  2. A self-priming, roller-free, miniature, peristaltic pump operable with a single, reciprocating actuator

    Science.gov (United States)

    Shkolnikov, Viktor; Ramunas, John; Santiago, Juan G.

    2013-01-01

    We present a design for a miniature self-priming peristaltic pump actuated with a single linear actuator, and which can be manufactured using conventional materials and methods. The pump is tolerant of bubbles and particles and can pump liquids, foams, and gases. We explore designs actuated by a motor (in depth) and a shape memory alloy (briefly); and briefly present a manually actuated version. The pump consists of a Delrin acetal plastic body with two integrated valves, a flexible silicone tube, and an actuator. Pumping is achieved as the forward motion of the actuator first closes the upstream valve, and then compresses a section of the tube. The increased internal pressure opens a downstream burst valve to expel the fluid. Reduced pressure in the pump tube allows the downstream valve to close, and removal of actuator force allows the upstream valve and pump tube to open, refilling the pump. The motor actuated design offers a linear dependence of flow rate on voltage in the range of 1.75–3 V. Flow rate decreases from 780 μl/min with increasing back pressure up to the maximum back pressure of 48 kPa. At 3 V and minimum back pressure, the pump consumes 90 mW. The shape memory alloy actuated design offers a 5-fold size and 4-fold weight reduction over the motor design, higher maximum back pressure, and substantial insensitivity of flow rate to back pressure at the cost of lower power efficiency and flow rate. The manually actuated version is simpler and appropriate for applications unconstrained by actuation distance. PMID:24672145

  3. Actuator topology design using the controllability Gramian

    DEFF Research Database (Denmark)

    Alves da Silveira, Otávio Augusto; Ono Fonseca, Jun Sérgio; Santos, Ilmar

    2015-01-01

    This work develops a methodology for the optimal design of actuators for the vibration control of flexible structures. The objective is the maximization of a measure of the controllability Gramian. The test case is the embedding of piezoelectric inserts in elastic structures for vibration control...... in modal space. A topology optimization was formulated to distribute two material phases in the domain: a passive linear elastic material and an active linear piezoelectric material, with a volume constraint in the latter. The objective function is the trace of the controllability Gramian of a LQR control...... system. Analytical sensitivities for the finite element model are derived for the objective function and constraints. Results are shown for two dimensional vibration control of a short beam with varying number of electrodes (control inputs) and vibration modes....

  4. Experimental-based Modelling and Simulation of Water Hydraulic Mechatronics Test Facilities for Motion Control and Operation in Environmental Sensitive Applications` Areas

    DEFF Research Database (Denmark)

    Conrad, Finn; Pobedza, J.; Sobczyk, A.

    2003-01-01

    proportional valves and servo actuators for motion control and power transmission undertaken in co-operation by Technical University, DTU and Cracow University of Technology, CUT. The results of this research co-operation include engineering design and test of simulation models compared with two mechatronic......The paper presents experimental-based modelling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions includes results from on-going research projects on fluid power and mechatronics based on tap water hydraulic...... test rig facilities powered by environmental friendly water hydraulic servo actuator system. Test rigs with measurement and data acquisition system were designed and build up with tap water hydraulic components of the Danfoss Nessie® product family. This paper presents selected experimental...

  5. Gear-Driven Turnbuckle Actuator

    Science.gov (United States)

    Rivera, Ricky N.

    2010-01-01

    This actuator design allows the extension and contraction of turnbuckle assemblies. It can be operated manually or remotely, and is extremely compact. It is ideal for turnbuckles that are hard to reach by conventional tools. The tool assembly design solves the problem of making accurate adjustments to the variable geometry guide vanes without having to remove and reinstall the actuator system back on the engine. The actuator does this easily by adjusting the length of the turnbuckles while they are still attached to the engine.

  6. FEMA DFIRM Hydraulic Structures

    Data.gov (United States)

    Minnesota Department of Natural Resources — This layer and accompanying attribute table is required whenever hydraulic structures are shown in the flood profile. It is also required if levees are shown on the...

  7. Tractor controls actuating force limits for Indian operators.

    Science.gov (United States)

    Mehta, C R; Pandey, M M; Tiwari, P S; Gite, L P; Khadatkar, Abhijit

    2011-01-01

    In four-wheel tractors, proper design of controls is important for comfortable and safe operation of the tractor. The design involves location and dimensions of controls as well as strength limits for operating these controls. The present study was aimed to quantify human strength for operation of tractor controls and to recommend the maximum control actuating forces for normal operation of tractors based on strength capability of 3,423 Indian male agricultural workers. The 5th percentile values of strength parameters i.e. leg strength sitting (left and right), foot strength sitting (right), torque strength (both hands) sitting, push strength (left hand and right hand) sitting and pull strength (left hand and right hand) sitting of agricultural workers collected using a strength measurement set-up were taken into consideration for the study. It was recommended that the maximum actuating forces for normal operation of frequently operated brake and clutch pedals of tractors should not exceed 260 N and 125 N based on 5th percentile values of right and left leg strength of male agricultural workers, respectively. The maximum actuating force required in steering wheel operation should not exceed 51 N based on 5th percentile value of torque strength (both hands) sitting of workers. The maximum actuating forces required for operating frequently operated levers viz. gear selection, speed selection, hydraulic control and hand throttle of Indian tractors should not exceed 46 N, 46 N, 25 N and 25 N, respectively. It may be concluded that the maximum actuating force limits as given in Bureau of Indian Standards IS 10703 are very high as compared to the findings of the study based on strength data of Indian male operators, which highlight the need to revise the standard.

  8. Energy-Efficient Variable Stiffness Actuators

    NARCIS (Netherlands)

    Visser, Ludo C.; Carloni, Raffaella; Stramigioli, Stefano

    2011-01-01

    Variable stiffness actuators are a particular class of actuators that is characterized by the property that the apparent output stiffness can be changed independent of the output position. To achieve this, variable stiffness actuators consist of a number of elastic elements and a number of actuated

  9. Constant-Pressure Hydraulic Pump

    Science.gov (United States)

    Galloway, C. W.

    1982-01-01

    Constant output pressure in gas-driven hydraulic pump would be assured in new design for gas-to-hydraulic power converter. With a force-multiplying ring attached to gas piston, expanding gas would apply constant force on hydraulic piston even though gas pressure drops. As a result, pressure of hydraulic fluid remains steady, and power output of the pump does not vary.

  10. Modelling and experimental validation of two-dimensional transverse vibrations in a flexible robot link

    DEFF Research Database (Denmark)

    Sørensen, Paul Haase; Baungaard, Jens Rane

    1996-01-01

    A general model for a rotating homogenous flexible robot link is developed. The model describes two-dimensional transverse vibrations induced by the actuator due to misalignment of the actuator axis of rotation relative to the link symmetry axis and due to translational acceleration of the link...

  11. Simulation of a spatial, servo-hydraulic test facility for space structures

    Science.gov (United States)

    Leimbach, K.-D.; Hahn, H.

    1994-01-01

    In this paper different control concepts for servo-hydraulic test facilities are derived using exact linearization techniques. Based on different linear and nonlinear models of the test table and the actuator dynamics several nonlinear controllers of different complexity are derived. The closed loop system performance of the controlled servo-hydraulic test facility is tested in various computer simulations using both, standard test signals and large test signals as system inputs. The simulation results turn out, that in case of standard input signals the test facility controller must include a linear test table mechanics model and a nonlinear servo-hydraulic actuator model. Additional simulations demonstrate the robustness of the control concept selected for standard test signals with respect to variations of plant parameters.

  12. Control Reconfigurability of Bilinear Hydraulic Drive Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Tahavori, Maryamsadat

    2011-01-01

    be effective if sufficient redundancy does not exist in the process. A measure for control reconfigurability which reveals the level of redundancy in connection with feedback control is proposed in this paper for bilinear systems. The proposed control reconfigurability measure is the extension of its gramian......The objective of the methods within the framework of the plug and play process control and particularly fault tolerant control is to establish control techniques which guarantee a certain performance through control reconfiguration at the occurrence of the faults or changes. These methods cannot......-based analogous counterpart, which has been previously proposed for the linear processes. The control reconfigurability is calculated for the bilinear models of an electro-hydraulic drive to show its relevance to redundant actuating capabilities in the models....

  13. Novel Cryogenic Actuator Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration —  New thin film low friction coating technologies have recently been developed and matured to the point for use in this IRAD actuator work.The new novel...

  14. Piezoelectric actuator for pulsating jets

    Science.gov (United States)

    Brissaud, Michel; Gonnard, Paul; Bera, Jean-Christophe; Sunyach, Michel

    2000-08-01

    Recent researches in aeronautics showed that fluidic actuator systems could offer possibilities for drag reduction and lift improvement. To this end many actuator types were designed. This paper deals with the design, fabrication and test of piezoelectric actuator in order to generate pulsated jets normal to a surface and control air flow separation. It is based on the flexural displacement of a rectangular metal plate clamped on one of its large edge. Piezoelectric patches cemented on the plate were used for driving into vibration the actuator. Experimental measurements show that pulsed flow velocities are adjustable from 1.5m/s to 35m/s through a 100x1mm2 slit andwithin a 100 to 400 Hz frequency range. Prototype provides the jet performances classically required for active control flow.

  15. Modeling and control of precision actuators

    CERN Document Server

    Kiong, Tan Kok

    2013-01-01

    IntroductionGrowing Interest in Precise ActuatorsTypes of Precise ActuatorsApplications of Precise ActuatorsNonlinear Dynamics and ModelingHysteresisCreepFrictionForce RipplesIdentification and Compensation of Preisach Hysteresis in Piezoelectric ActuatorsSVD-Based Identification and Compensation of Preisach HysteresisHigh-Bandwidth Identification and Compensation of Hysteretic Dynamics in Piezoelectric ActuatorsConcluding RemarksIdentification and Compensation of Frict

  16. Flexure-based nanomagnetic actuators

    Science.gov (United States)

    Vasquez, Daniel James

    Nanometer-scale actuators powered through applied-magnetic fields have been designed, fabricated, and tested. These actuators consist of one or more ferromagnetic elements attached to a mechanical flexure. Two types of flexures were studied including a cantilever beam that is fixed on one end, and free on the other. The free end of the cantilever is attached to a, ferromagnetic element allowing a bending torque to be applied by a magnetic field. The second type of actuator design uses a set of torsion beams that are each anchored on one end, and attached to the magnetic element on the other end. The torsion beams are designed such that the application of a magnetic field will result in a twist along the long axis of the beam with little to no bending. The smallest fabricated and tested device is a cantilever-based ferromagnetic actuator that consists of a single 1.5-mum-long, 338-nm-wide, and 50-nm-thick nickel element, and a 2.2-mum-long, 110-nm-wide, and 30-nm-thick gold cantilever beam. A deflection of over 17° was measured for this actuator, while a similar one with a 10.1-mum long cantilever beam experienced measured deflections up to 57°. Torsion-based ferromagnetic actuators have been fabricated and tested with 110-nm-wide, and 50-rim-thick magnetic elements. Such magnetic elements contain only a single saturated magnetic domain. The ultimate scalability of ferromagnetic actuation is limited by the ability of thermal noise to affect the temporal stability of a nanometer-scale magnet. Theory to describe thermal noise and ultimate scalability of the ferromagnetic actuators has been developed. The size of the ferromagnetic actuators studied in this manuscript are smaller than most plant and animal cells. This enables the possibility of such actuators to manipulate a, living cell on an intracellular level. Other potential applications of such small actuators include MHz, to GHz frequency resonators, and tunable optical filters.

  17. High torque miniature rotary actuator

    Science.gov (United States)

    Nalbandian, Ruben

    2005-07-01

    This paper summarizes the design and the development of a miniature rotary actuator (36 mm diameter by 100 mm length) used in spacecraft mechanisms requiring high torques and/or ultra-fine step resolution. This actuator lends itself to applications requiring high torque but with strict volume limitations which challenge the use of conventional rotary actuators. The design challenge was to develop a lightweight (less than 500 grams), very compact, high bandwidth, low power, thermally stable rotary actuator capable of producing torques in excess of 50 N.m and step resolutions as fine as 0.003 degrees. To achieve a relatively high torsional stiffness in excess of 1000 Nm/radian, the design utilizes a combination of harmonic drive and multistage planetary gearing. The unique design feature of this actuator that contributes to its light weight and extremely precise motion capability is a redundant stepper motor driving the output through a multistage reducing gearbox. The rotary actuator is powered by a high reliability space-rated stepper motor designed and constructed by Moog, Inc. The motor is a three-phase stepper motor of 15 degree step angle, producing twenty-four full steps per revolution. Since micro-stepping is not used in the design, and un-powered holding torque is exhibited at every commanded step, the rotary actuator is capable of reacting to torques as high as 35 Nm by holding position with the power off. The output is driven through a gear transmission having a total train ratio of 5120:1, resulting in a resolution of 0.003 degrees output rotation per motor step. The modular design of the multi-stage output transmission makes possible the addition of designs having different output parameters, such as lower torque and higher output speed capability. Some examples of an actuator family based on this growth capability will be presented in the paper.

  18. Soft Pneumatic Actuators for Rehabilitation

    OpenAIRE

    Guido Belforte; Gabriella Eula; Alexandre Ivanov; Silvia Sirolli

    2014-01-01

    Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM) in rehabilitation apparatus is described and the general characteri...

  19. Soft Pneumatic Actuators for Rehabilitation

    Directory of Open Access Journals (Sweden)

    Guido Belforte

    2014-05-01

    Full Text Available Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM in rehabilitation apparatus is described and the general characteristics required in different applications are considered, analyzing the use of proper soft actuators with various technical properties. Therefore, research activity carried out in the Department of Mechanical and Aerospace Engineering in the field of soft and textile actuators is presented here. In particular, pneumatic textile muscles useful for active suits design are described. These components are made of a tubular structure, with an inner layer of latex coated with a deformable outer fabric sewn along the edge. In order to increase pneumatic muscles forces and contractions Braided Pneumatic Muscles are studied. In this paper, new prototypes are presented, based on a fabric construction and various kinds of geometry. Pressure-force-deformation tests results are carried out and analyzed. These actuators are useful for rehabilitation applications. In order to reproduce the whole upper limb movements, new kind of soft actuators are studied, based on the same principle of planar membranes deformation. As an example, the bellows muscle model and worm muscle model are developed and described. In both cases, wide deformations are expected. Another issue for soft actuators is the pressure therapy. Some textile sleeve prototypes developed for massage therapy on patients suffering of lymph edema are analyzed. Different types of fabric and assembly techniques have been tested. In general, these Pressure Soft Actuators are useful for upper/lower limbs treatments

  20. Review and prospect of research on hydraulic pulsation attenuator

    Science.gov (United States)

    Shan, Chang-ji; Zhao, Qi-jun; Dai, Ting-ting; Bian, Yi-duo; Cai, Yan

    2017-09-01

    The pressure pulsation attenuator is able to decrease the fluid fluctuation of the hydraulic pump effectively, so it is widely used in construction machinery. This paper reviews the history and progresses of the research on the pressure pulsation attenuator in China and overseas, summarizes its two types: H-type rigid structure and built-in flexible material, meanwhile, discusses its future research area.

  1. Flexible Sigmoidoscopy

    Science.gov (United States)

    ... Task Force (USPSTF). Most doctors recommend colonoscopy to screen for colon cancer because colonoscopy shows the entire colon and can remove colon polyps. However, preparing for and performing a flexible sigmoidoscopy may take less time and you may ...

  2. Large Scale Magnetostrictive Valve Actuator

    Science.gov (United States)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  3. Control of Adjustable Compliant Actuators

    Directory of Open Access Journals (Sweden)

    Berno J.E. Misgeld

    2014-05-01

    Full Text Available Adjustable compliance or variable stiffness actuators comprise an additional element to elastically decouple the actuator from the load and are increasingly applied to human-centered robotic systems. The advantages of such actuators are of paramount importance in rehabilitation robotics, where requirements demand safe interaction between the therapy system and the patient. Compliant actuator systems enable the minimization of large contact forces arising, for example, from muscular spasticity and have the ability to periodically store and release energy in cyclic movements. In order to overcome the loss of bandwidth introduced by the elastic element and to guarantee a higher range in force/torque generation, new actuator designs consider variable or nonlinear stiffness elements, respectively. These components cannot only be adapted to the walking speed or the patient condition, but also entail additional challenges for feedback control. This paper introduces a novel design method for an impedance-based controller that fulfills the control objectives and compares the performance and robustness to a classical cascaded control approach. The new procedure is developed using a non-standard positive-real Η2 controller design and is applied to a loop-shaping approach. Robust norm optimal controllers are designed with regard to the passivity of the actuator load-impedance transfer function and the servo control problem. Classical cascaded and positive-real Η2 controller designs are validated and compared in simulations and in a test bench using a passive elastic element of varying stiffness.

  4. Active vibration control of spatial flexible multibody systems

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Maria Augusta, E-mail: augusta.neto@dem.uc.pt [Universidade de Coimbra (Polo II), Departamento de Engenharia Mecanica, Faculdade de Ciencia e Tecnologia (Portugal); Ambrosio, Jorge A. C., E-mail: jorge@dem.ist.utl.pt [Instituto Superior Tecnico, Instituto de Engenharia Mecanica (Portugal); Roseiro, Luis M., E-mail: lroseiro@isec.pt [Instituto Superior de Engenharia de Coimbra, Departamento de Engenharia Mecanica (Portugal); Amaro, A., E-mail: ana.amaro@dem.uc.pt [Universidade de Coimbra (Polo II), Departamento de Engenharia Mecanica, Faculdade de Ciencia e Tecnologia (Portugal); Vasques, C. M. A., E-mail: cvasques@inegi.up.pt [Universidade do Porto, INEGI-Instituto de Engenharia Mecanica e Gestao Industrial (Portugal)

    2013-06-15

    In this work a flexible multibody dynamics formulation of complex models including elastic components made of composite materials is extended to include piezoelectric sensors and actuators. The only limitation for the deformation of a structural member is that they must remain elastic and linear when described in a coordinate frame fixed to a material point or region of its domain. The flexible finite-element model of each flexible body is obtained referring the flexible body nodal coordinates to the body fixed frame and using a diagonalized mass description of the inertia in the mass matrix and on the gyroscopic force vector. The modal superposition technique is used to reduce the number of generalized coordinates to a reasonable dimension for complex shaped structural models of flexible bodies. The active vibration control of the flexible multibody components is implemented using an asymmetric collocated piezoelectric sensor/actuator pair. An electromechanically coupled model is taken into account to properly consider the surface-bonded piezoelectric transducers and their effects on the time and spatial response of the flexible multibody components. The electromechanical effects are introduced in the flexible multibody equations of motion by the use of beam and plate/shell elements, developed to this purpose. A comparative study between the classical control strategies, constant gain and amplitude velocity feedback, and optimal control strategy, linear quadratic regulator (LQR), is performed in order to investigate their effectiveness to suppress vibrations in structures with piezoelectric sensing and actuating patches.

  5. PID Controller Optimization by GA and Its Performances on the Electro-hydraulic Servo Control System

    Institute of Scientific and Technical Information of China (English)

    Karam M. Eibayomy; Jiao Zongxia; Zhang Huaqing

    2008-01-01

    A proportional integral derivative (PID) controller is designed and attached to electro-hydraulic servo actuator system (EHSAS) to control the angular position of the rotary actuator which control the movable surface of space vehicles. The PID gain parameters areoptimized by the genetic algorithm (GA). The controller is verified on the new state-space model of servo-valves attached to the physical rotary actuator by SIMULINK program. The controller and the state-space model are verified experimentally. Simulation and experimental results verify the effectiveness of the PID controller adaptive by GA to control the angular position of the rotary actuator as compared with the classical PID controller and the compensator controller.

  6. Velocity feedback control with a flywheel proof mass actuator

    Science.gov (United States)

    Kras, Aleksander; Gardonio, Paolo

    2017-08-01

    This paper presents four new proof mass actuators to be used in velocity feedback control systems for the control of vibrations of machines and flexible structures. A classical proof mass actuator is formed by a coil-magnet linear motor, with either the magnet or the armature-coil proof mass suspended on soft springs. This arrangement produces a net force effect at frequencies above the fundamental resonance frequency of the springs-proof mass system. Thus, it can be used to implement point velocity feedback loops, although the dynamic response and static deflection of the springs-proof mass system poses some stability and control performance limitations. The four proof mass actuators presented in this study include a flywheel element, which is used to augment the inertia effect of the suspended proof mass. The paper shows that the flywheel element modifies both the dynamic response and static deflection of the springs-proof mass system in such a way as the stability and control performance of velocity feedback loops using these actuators are significantly improved.

  7. Modeling and optimization of magnetostrictive actuator amplified by compliant mechanism

    Science.gov (United States)

    Niu, Muqing; Yang, Bintang; Yang, Yikun; Meng, Guang

    2017-09-01

    Magnetostrictive actuators are commonly used in precision engineering with the advantages of high resolution and fast response. Their limited strokes are always amplified by compliant mechanisms without wear and backlash. This paper proposes a hybrid model for the actuation system considering the coupling of the actuator and the amplifier. The magnetostrictive model, based on the Jiles-Atherton model, is related to the input stiffness of the amplifier when quantifying the magneto-mechanical effects, including stress-dependent magnetization, stress-dependent magnetostriction and ΔE effect. The compliant mechanism model aims at constructing the flexibility matrix with the amplification ratio and input stiffness related to the spring factor of the load. The deformation and structural stress of the amplifier are also dependent on the output strain of magnetostrictive material. Experiments under both free load and spring load conditions have been done to verify the effectiveness of the hybrid model. The proposed model is suitable for parameter optimization and the performance indicators can be precisely quantified. Optimization based on hybrid model is more preferred than optimizing the actuator and amplifier independently for maximum output displacement. Furthermore, ‘stiffness match principle’ is no longer applicable when considering ΔE effect, and the optimal external stiffness problem can be numerically solved by the hybrid model for maximum output energy of magnetostrictive material.

  8. Conducting IPN actuator/sensor for biomimetic vibrissa system

    Science.gov (United States)

    Festin, N.; Plesse, C.; Pirim, P.; Chevrot, C.; Vidal, F.

    2014-03-01

    Electroactive polymers, or EAPs, are polymers that exhibit a change in size or shape when stimulated by an electric field. The most common applications of this type of material are in actuators and sensors. One promising technology is the elaboration of electronic conducting polymers based actuators with Interpenetrating Polymer Networks (IPNs) architecture. Their many advantageous properties as low working voltage, light weight and high lifetime make them very attractive for various applications including robotics. Conducting IPNs were fabricated by oxidative polymerization of 3,4-ethylenedioxythiophene within a flexible Solid Polymer Electrolytes (SPE) combining poly(ethylene oxide) and Nitrile Butadiene Rubber. SPE mechanical properties and ionic conductivities in the presence of 1-ethyl-3- methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI) have been characterized. The presence of the elastomer within the SPE greatly improves the actuator performances. The free strain as well as the blocking force was characterized as a function of the actuator length. The sensing properties of those conducting IPNs allow their integration into a biomimetic perception prototype: a system mimicking the tactile perception of rat vibrissae.

  9. Trend of hydraulic units

    Energy Technology Data Exchange (ETDEWEB)

    Deshimaru, Jun' ichi

    1988-11-01

    The gear, vane and piston pumps occupy a more then 90% share in the hydraulic pumps. Comparatively large pumps are mainly variable delivery piston pumps. The piston pumps are comparatively high in output density (output per unit weight), indicating the hydraulic pump in performance, and tend to become higher and higher in it. Though they are mainly 210 to 350kgf/cm/sup 2/ in rated pressure, some of them come to surpass 400kgf/cm/sup 3/ in it. While the progress in computation also requires the high speed operation, high accuracy and other severe conditions for the hydraulic units, which accordingly and increasingly intensify the requirement for hydraulic oil in abrasion resistibility, oxidation stability and response characteristics. While cavitation comes to easily occur, which considerably and disadvantageously influences hydraulic oil in life through degradation, noise level and respondingness. From now on, the development of high performance oil and study of mechanical structure are important. 19 references, 9 figures, 2 tables.

  10. Unsteady fluid flow in smart material actuated fluid pumps

    Science.gov (United States)

    John, Shaju; Cadou, Christopher

    2005-05-01

    Smart materials' ability to deliver large block forces in a small package while operating at high frequencies makes them extremely attractive for converting electrical to mechanical power. This has led to the development of hybrid actuators consisting of co-located smart material actuated pumps and hydraulic cylinders that are connected by a set of fast-acting valves. The overall success of the hybrid concept hinges on the effectiveness of the coupling between the smart material and the fluid. This, in turn, is strongly dependent on the resistance to fluid flow in the device. This paper presents results from three-dimensional unsteady simulations of fluid flow in the pumping chamber of a prototype hybrid actuator powered by a piezo-electric stack. The results show that the forces associated with moving the fluid into and out of the pumping chamber already exceed 10% of the piezo stack blocked force at relatively low frequencies ~120 Hz and approach 40% of the blocked force at 800 Hz. This reduces the amplitude of the piston motion in such a way that the volume flow rate remains approximately constant above operating frequencies of 500 Hz while the efficiency of the pump decreases rapidly.

  11. Superhydrophobicity enhancement through substrate flexibility.

    Science.gov (United States)

    Vasileiou, Thomas; Gerber, Julia; Prautzsch, Jana; Schutzius, Thomas M; Poulikakos, Dimos

    2016-11-22

    Inspired by manifestations in nature, microengineering and nanoengineering of synthetic materials to achieve superhydrophobicity has been the focus of much work. Generally, hydrophobicity is enhanced through the combined effects of surface texturing and chemistry; being durable, rigid materials are the norm. However, many natural and technical surfaces are flexible, and the resulting effect on hydrophobicity has been largely ignored. Here, we show that the rational tuning of flexibility can work synergistically with the surface microtexture or nanotexture to enhance liquid repellency performance, characterized by impalement and breakup resistance, contact time reduction, and restitution coefficient increase. Reduction in substrate areal density and stiffness imparts immediate acceleration and intrinsic responsiveness to impacting droplets (∼350 × g), mitigating the collision and lowering the impalement probability by ∼60% without the need for active actuation. Furthermore, we exemplify the above discoveries with materials ranging from man-made (thin steel or polymer sheets) to nature-made (butterfly wings).

  12. Electromechanical actuator with controllable motion, fast response rate, and high-frequency resonance based on graphene and polydiacetylene.

    Science.gov (United States)

    Liang, Jiajie; Huang, Lu; Li, Na; Huang, Yi; Wu, Yingpeng; Fang, Shaoli; Oh, Jiyoung; Kozlov, Mikhail; Ma, Yanfeng; Li, Feifei; Baughman, Ray; Chen, Yongsheng

    2012-05-22

    Although widely investigated, novel electromechanical actuators with high overall actuation performance are still in urgent need for various practical and scientific applications, such as robots, prosthetic devices, sensor switches, and sonar projectors. In this work, combining the properties of unique environmental perturbations-actuated deformational isomerization of polydiacetylene (PDA) and the outstanding intrinsic features of graphene together for the first time, we design and fabricate an electromechanical bimorph actuator composed of a layer of PDA crystal and a layer of flexible graphene paper through a simple yet versatile solution approach. Under low applied direct current (dc), the graphene-PDA bimorph actuator with strong mechanical strength can generate large actuation motion (curvature is about 0.37 cm(-1) under a current density of 0.74 A/mm(2)) and produce high actuation stress (more than 160 MPa/g under an applied dc of only 0.29 A/mm(2)). When applying alternating current (ac), this actuator can display reversible swing behavior with long cycle life under high frequencies even up to 200 Hz; significantly, while the frequency and the value of applied ac and the state of the actuators reach an appropriate value, the graphene-PDA actuator can produce a strong resonance and the swing amplitude will jump to a peak value. Moreover, this stable graphene-PDA actuator also demonstrates rapidly and partially reversible electrochromatic phenomenon when applying an ac. Two mechanisms-the dominant one, electric-induced deformation, and a secondary one, thermal-induced expansion of PDA-are proposed to contribute to these interesting actuation performances of the graphene-PDA actuators. On the basis of these results, a mini-robot with controllable direction of motion based on the graphene-PDA actuator is designed to illustrate the great potential of our discoveries for practical use. Combining the unique actuation mechanism and many outstanding properties of

  13. Actuator device utilizing a conductive polymer gel

    Science.gov (United States)

    Chinn, Douglas A.; Irvin, David J.

    2004-02-03

    A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

  14. Trans-permanent magnetic actuation

    Science.gov (United States)

    Farmer, Daniel Jay

    The demands for an actuator to deploy, position and shape large spaced-based structures form a unique set of design criteria. In many applications it is desirable to hold displacements or forces between two points to within specified requirements (the regulation problem) and to periodically to change position (the tracking problem). Furthermore, the interest generally lies in satisfying the dynamic performance requirements while expending minimal power, while meeting tight tolerances and while experiencing little wear and fatigue. The actuator must also be able to withstand a variety of operational conditions such as impacts and thermal changes over an extended period of time. Current trends in large-scale structures have addressed the demands by using conventional actuators and motors, along with elaborate linkages or mechanisms to shape, position, protect and deploy. The developed designs use unique characteristics of permanent magnets to create simple direct-acting actuators and motors very suitable for space based structures. The developed trans-permanent magnetic (T-PM) actuators and motors are systems consisting of one or more permanent magnets, some of whose magnetic strengths can be switched on-board by surrounding pulse-coils. The T-PM actuator and motors expend no power during regulation. The T-PM can periodically change or remove the strength of its own magnets thereby enabling both fine-tune adjustments (microsteps) and large-scale adjustments (rotation). The fine (microstep) adjustments are particularly helpful in thermally varying space environments. The large-scale adjustments (rotation) are particularly helpful in deployment where the structure or antenna must experience large-angle rotations and/or large displacements. T-PM concepts are illustrated in direct acting actuators and built into stepper motor and permanent magnet motor applications. Several examples of design, analysis and testing are developed to verify the technology and supporting

  15. Flywheel energy storage for electromechanical actuation systems

    Science.gov (United States)

    Hockney, Richard L.; Goldie, James H.; Kirtley, James L.

    1991-01-01

    The authors describe a flywheel energy storage system designed specifically to provide load-leveling for a thrust vector control (TVC) system using electromechanical actuators (EMAs). One of the major advantages of an EMA system over a hydraulic system is the significant reduction in total energy consumed during the launch profile. Realization of this energy reduction will, however, require localized energy storage capable of delivering the peak power required by the EMAs. A combined flywheel-motor/generator unit which interfaces directly to the 20-kHz power bus represents an ideal candidate for this load leveling. The overall objective is the definition of a flywheel energy storage system for this application. The authors discuss progress on four technical objectives: (1) definition of the specifications for the flywheel-motor/generator system, including system-level trade-off analysis; (2) design of the flywheel rotor; (3) design of the motor/generator; and (4) determination of the configuration for the power management system.

  16. Cavitation in Hydraulic Machinery

    Energy Technology Data Exchange (ETDEWEB)

    Kjeldsen, M.

    1996-11-01

    The main purpose of this doctoral thesis on cavitation in hydraulic machinery is to change focus towards the coupling of non-stationary flow phenomena and cavitation. It is argued that, in addition to turbulence, superimposed sound pressure fluctuations can have a major impact on cavitation and lead to particularly severe erosion. For the design of hydraulic devices this finding may indicate how to further limit the cavitation problems. Chapter 1 reviews cavitation in general in the context of hydraulic machinery, emphasizing the initial cavitation event and the role of the water quality. Chapter 2 discusses the existence of pressure fluctuations for situations common in such machinery. Chapter 3 on cavitation dynamics presents an algorithm for calculating the nucleation of a cavity cluster. Chapter 4 describes the equipment used in this work. 53 refs., 55 figs.,10 tabs.

  17. Characteristic Evaluation of a Shrouded Propeller Mechanism for a Magnetic Actuated Microrobot

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2015-09-01

    Full Text Available Medical microrobots have been widely used in clinical applications, particularly the spiral type locomotion mechanism, which was recently considered one of the main self-propelling mechanisms for the next medical microrobot to perform tasks such as capsule endoscopy and drug delivery. However, limits in clinical applications still exist. The spiral action of the microrobot while being used for diagnosis may lead to pain or even damage to the intestinal wall due to the exposed mechanisms. Therefore, a new locomotive mechanism, named the shrouded propeller mechanism, was proposed to achieve a high level of medical safety as well as effective propulsive performance in our study. The shrouded propeller mechanism consists of a bare spiral propeller and a non-rotating nozzle. To obtain a high effective propulsive performance, two types of screw grooves with different shapes including the cylindrical screw groove and the rectangular screw groove with different parameters were analyzed using the shrouded model. Two types of magnetic actuated microrobots with different driving modes, the electromagnetic (three-pole rotor actuated microrobot and the permanent magnet (O-ring type magnet actuated microrobot were designed to evaluate the performance of the electromagnetic actuation system. Based on experimental results, the propulsive force of the proposed magnetic actuated microrobot with a shrouded propeller was larger than the magnetic actuated microrobot with a bare spiral propeller under the same parameters. Additionally, the shrouded propeller mechanism as an actuator can be used for other medical microrobots for flexible locomotion.

  18. The effect of plasma actuator on the depreciation of the aerodynamic drag on box model

    Science.gov (United States)

    Harinaldi, Budiarso, Julian, James; Rabbani M., N.

    2016-06-01

    Recent active control research advances have provided many benefits some of which in the field of transportation by land, sea as well as by air. Flow engineering by using active control has proven advantages in energy saving significantly. One of the active control equipment that is being developed, especially in the 21st century, is a plasma actuator, with the ability to modify the flow of fluid by the approach of ion particles makes these actuators a very powerful and promising tool. This actuator can be said to be better to the previously active control such as suction, blowing and synthetic jets because it is easier to control, more flexible because it has no moving parts, easy to be manufactured and installed, and consumes a small amount of energy with maximum capability. Plasma actuator itself is the composition of a material composed of copper and a dielectric sheet, where the copper sheets act as an electricity conductor and the dielectric sheet as electricity insulator. Products from the plasma actuators are ion wind which is the result of the suction of free air around the actuator to the plasma zone. This study investigates the ability of plasma actuators in lowering aerodynamic drag which is commonly formed in the models of vehicles by varying the shape of geometry models and the flow speed.

  19. A multi-segment soft actuator for biomedical applications based on IPMCs

    Science.gov (United States)

    Zhao, Dongxu; Wang, Yanjie; Liu, Jiayu; Luo, Meng; Li, Dichen; Chen, Hualing

    2015-04-01

    With rapid progress of biomedical devices towards miniaturization, flexibility, multifunction and low cost, the restrictions of traditional mechanical structures become particularly apparent, while soft materials become research focus in broad fields. As one of the most attractive soft materials, Ionic Polymer-Metal Composite (IPMC) is widely used as artificial muscles and actuators, with the advantages of low driving-voltage, high efficiency of electromechanical transduction and functional stabilization. In this paper, a new intuitive control method was presented to achieve the omnidirectional bending movements and was applied on a representative actuation structure of a multi-degree-offreedom soft actuator composed of two segments bar-shaped IPMC with a square cross section. Firstly, the bar-shaped IPMCs were fabricated by the solution casting method, reducing plating, autocatalytic plating method and cut into shapes successively. The connectors of the multi-segment IPMC actuator were fabricated by 3D printing. Then, a new control method was introduced to realize the intuitive mapping relationship between the actuator and the joystick manipulator. The control circuit was designed and tested. Finally, the multi-degree-of-freedom actuator of 2 segments bar-shaped IPMCs was implemented and omnidirectional bending movements were achieved, which could be a promising actuator for biomedical applications, such as endoscope, catheterism, laparoscopy and the surgical resection of tumors.

  20. Hydraulics and pneumatics

    CERN Document Server

    Parr, Andrew

    2006-01-01

    Nearly all industrial processes require objects to be moved, manipulated or subjected to some sort of force. This is frequently accomplished by means of electrical equipment (such as motors or solenoids), or via devices driven by air (pneumatics) or liquids (hydraulics).This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatic systems for all engineers and technicians who wish to have an insight into the components and operation of such a system.This second edition has been fully updated to include all recent developments su

  1. Popeye Project: Hydraulic umbilical

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, K.G.; Williams, V.T.

    1996-12-31

    For the Popeye Project, the longest super-duplex hydraulic umbilical in the world was installed in the Gulf of Mexico. This paper reports on its selection and project implementation. Material selection addresses corrosion in seawater, water-based hydraulic fluid, and methanol. Five alternatives were considered: (1) carbon-steel with traditional coating and anodes, (2) carbon-steel coated with thermally sprayed aluminum, (3) carbon-steel sheathed in aluminum, (4) super-duplex, and (5) titanium. The merits and risks associated with each alternative are discussed. The manufacture and installation of the selected umbilical are also reported.

  2. Energy efficient fluid powered linear actuator with variable area and concentric chambers

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Randall F.; Love, Lonnie J.

    2016-11-15

    Hydraulic actuation systems having concentric chambers, variable displacements and energy recovery capabilities include cylinders with pistons disposed inside of barrels. When operating in energy consuming modes, high speed valves pressurize extension chambers or retraction chambers to provide enough force to meet or counteract an opposite load force. When operating in energy recovery modes, high speed valves return a working fluid from extension chambers or retraction chambers, which are pressurized by a load, to an accumulator for later use.

  3. Valve and Manifold considerations for Efficient Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Nørgård, Christian; Bech, Michael Møller

    2016-01-01

    This paper seeks to shed light on the topic of design and sizing of switching valves and connecting manifolds found in large digital hydraulic motors, also known commercially as Digital Displacement Motors. These motors promise very high operation efficiencies with broad operation ranges, which set...... strict requirements to the switching valves and the overall manifold design. To investigate this topic, the largest known digital motor (3.5 megawatt) is studied using models and optimization. Based on the limited information available about this motor, a detailed reconstruction of the motor architecture...... valves when considering also the manifold flow losses. A global optimization is conducted by use of the generalized differential evolution 3 algorithm, where the valve diameters, valve stroke lengths, actuator force capabilities and actuator timing signals are used as design variables. The results...

  4. A Crawler Climbing Robot Integrating Electroadhesion and Electrostatic Actuation

    Directory of Open Access Journals (Sweden)

    Hongqiang Wang

    2014-12-01

    Full Text Available Previous electroadhesive climbing robots generally employed typical electromagnetic motors, which spoiled some of the advantages of electroadhesion such as it being light, thin and flexible. To improve these, an integration of electrostatic actuation and adhesion was utilized in this work. By using FEM analyses, the present paper analysed the effect of design parameters on adhesive and driving forces respectively, and examined the possible interference between electrostatic actuation and adhesion inside the integration. Then this article discussed the driving force, payload capacity and torque balance of the robot with the integration. Based on these analyses, we designed and fabricated a lightweight (94 g and low-height (15 mm prototype with electrode films made by screen printing. Experiments on the prototype demonstrated that it can adhere to a vertical wall stably and move at a maximum speed of 35.3 mm/s.

  5. Pneumatic Variable Series Elastic Actuator.

    Science.gov (United States)

    Zheng, Hao; Wu, Molei; Shen, Xiangrong

    2016-08-01

    Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.

  6. Mechanics of Actuated Disc Cutting

    Science.gov (United States)

    Dehkhoda, Sevda; Detournay, Emmanuel

    2017-02-01

    This paper investigates the mechanics of an actuated disc cutter with the objective of determining the average forces acting on the disc as a function of the parameters characterizing its motion. The specific problem considered is that of a disc cutter revolving off-centrically at constant angular velocity around a secondary axis rigidly attached to a cartridge, which is moving at constant velocity and undercutting rock at a constant depth. This model represents an idealization of a technology that has been implemented in a number of hard rock mechanical excavators with the goal of reducing the average thrust force to be provided by the excavation equipment. By assuming perfect conformance of the rock with the actuated disc as well as a prescribed motion of the disc (perfectly rigid machine), the evolution of the contact surface between the disc and the rock during one actuation of the disc can be computed. Coupled with simple cutter/rock interaction models that embody either a ductile or a brittle mode of fragmentation, these kinematical considerations lead to an estimate of the average force on the cartridge and of the partitioning of the energy imparted by the disc to the rock between the actuation mechanism of the disc and the translation of the cartridge on which the actuated disc is attached.

  7. Piping Flexibility

    Science.gov (United States)

    1978-01-01

    A NASA computer program aids Hudson Engineering Corporation, Houston, Texas, in the design and construction of huge petrochemical processing plants like the one shown, which is located at Ju'aymah, Saudi Arabia. The pipes handling the flow of chemicals are subject to a variety of stresses, such as weight and variations in pressure and temperature. Hudson Engineering uses a COSMIC piping flexibility analysis computer program to analyze stresses and unsure the necessary strength and flexibility of the pipes. This program helps the company realize substantial savings in reduced engineering time.

  8. Demonstrating the application of dielectric polymer actuators for tactile feedback in a mobile consumer device.

    NARCIS (Netherlands)

    Moessinger, H.M.; Brokken, D.

    2010-01-01

    User interfaces of mobile consumer devices are becoming increasingly complex. To address this complexity touch-screen interfaces are used. They allow flexible design of the user interfaces but lack the tactile feedback mechanical buttons provide, limiting ease of use. Dielectric Elastomer Actuator

  9. Demonstrating the application of dielectric polymer actuators for tactile feedback in a mobile consumer device.

    NARCIS (Netherlands)

    Moessinger, H.M.; Brokken, D.

    2010-01-01

    User interfaces of mobile consumer devices are becoming increasingly complex. To address this complexity touch-screen interfaces are used. They allow flexible design of the user interfaces but lack the tactile feedback mechanical buttons provide, limiting ease of use. Dielectric Elastomer Actuator (

  10. Demonstrating the application of dielectric polymer actuators for tactile feedback in a mobile consumer device.

    NARCIS (Netherlands)

    Moessinger, H.M.; Brokken, D.

    2010-01-01

    User interfaces of mobile consumer devices are becoming increasingly complex. To address this complexity touch-screen interfaces are used. They allow flexible design of the user interfaces but lack the tactile feedback mechanical buttons provide, limiting ease of use. Dielectric Elastomer Actuator (

  11. Shape memory alloy actuated accumulator for ultra-deepwater oil and gas exploration

    Science.gov (United States)

    Patil, Devendra; Song, Gangbing

    2016-04-01

    As offshore oil and gas exploration moves further offshore and into deeper waters to reach hydrocarbon reserves, it is becoming essential for the industry to develop more reliable and efficient hydraulic accumulators to supply pressured hydraulic fluid for various control and actuation operations, such as closing rams of blowout preventers and controlling subsea valves on the seafloor. By utilizing the shape memory effect property of nitinol, which is a type of shape memory alloy (SMA), an innovative SMA actuated hydraulic accumulator prototype has been developed and successfully tested at Smart Materials and Structure Laboratory at the University of Houston. Absence of gas in the developed SMA accumulator prototype makes it immune to hydrostatic head loss caused by water depth and thus reduces the number of accumulators required in deep water operations. Experiments with a feedback control have demonstrated that the proposed SMA actuated accumulator can provide precisely regulated pressurized fluids. Furthermore the potential use of ultracapacitors along with an embedded system to control the electric power supplied to SMA allows this accumulator to be an autonomous device for deployment. The developed SMA accumulator will make deepwater oil extraction systems more compact and cost effective.

  12. HYDRAULICS, TUSCARAWAS COUNTY, OHIO, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydraulic procedures for estimating flood discharges for a flood insurance...

  13. Modeling of reliability and performance assessment of a dissimilar redundancy actuation system with failure monitoring

    Institute of Scientific and Technical Information of China (English)

    Wang Shaoping; Cui Xiaoyu; Shi Jian; Mileta M. Tomovic; Jiao Zongxia

    2016-01-01

    Actuation system is a vital system in an aircraft, providing the force necessary to move flight control surfaces. The system has a significant influence on the overall aircraft performance and its safety. In order to further increase already high reliability and safety, Airbus has imple-mented a dissimilar redundancy actuation system (DRAS) in its aircraft. The DRAS consists of a hydraulic actuation system (HAS) and an electro-hydrostatic actuation system (EHAS), in which the HAS utilizes a hydraulic source (HS) to move the control surface and the EHAS utilizes an elec-trical supply (ES) to provide the motion force. This paper focuses on the performance degradation processes and fault monitoring strategies of the DRAS, establishes its reliability model based on the generalized stochastic Petri nets (GSPN), and carries out a reliability assessment considering the fault monitoring coverage rate and the false alarm rate. The results indicate that the proposed reli-ability model of the DRAS, considering the fault monitoring, can express its fault logical relation and redundancy degradation process and identify potential safety hazards.

  14. Speed Sensorless Induction Motor Drives for Electrical Actuators: Schemes, Trends and Tradeoffs

    Science.gov (United States)

    Elbuluk, Malik E.; Kankam, M. David

    1997-01-01

    For a decade, induction motor drive-based electrical actuators have been under investigation as potential replacement for the conventional hydraulic and pneumatic actuators in aircraft. Advantages of electric actuator include lower weight and size, reduced maintenance and operating costs, improved safety due to the elimination of hazardous fluids and high pressure hydraulic and pneumatic actuators, and increased efficiency. Recently, the emphasis of research on induction motor drives has been on sensorless vector control which eliminates flux and speed sensors mounted on the motor. Also, the development of effective speed and flux estimators has allowed good rotor flux-oriented (RFO) performance at all speeds except those close to zero. Sensorless control has improved the motor performance, compared to the Volts/Hertz (or constant flux) controls. This report evaluates documented schemes for speed sensorless drives, and discusses the trends and tradeoffs involved in selecting a particular scheme. These schemes combine the attributes of the direct and indirect field-oriented control (FOC) or use model adaptive reference systems (MRAS) with a speed-dependent current model for flux estimation which tracks the voltage model-based flux estimator. Many factors are important in comparing the effectiveness of a speed sensorless scheme. Among them are the wide speed range capability, motor parameter insensitivity and noise reduction. Although a number of schemes have been proposed for solving the speed estimation, zero-speed FOC with robustness against parameter variations still remains an area of research for speed sensorless control.

  15. Coupled-disturbance-observer-based position tracking control for a cascade electro-hydraulic system.

    Science.gov (United States)

    Guo, Qing; Yin, Jing-Min; Yu, Tian; Jiang, Dan

    2017-05-01

    The disturbance suppression is one of the most common control problems in electro-hydraulic systems. especially largely an unknown disturbance often obviously degrades the dynamic performance by biasing the desired actuator outputs (e.g., load forces or torques). In order to reject the dynamic disturbances in some multi-degree-of-freedom manipulators driven by electro-hydraulic actuators, this paper proposes a state feedback control of the cascade electro-hydraulic system based on a coupled disturbance observer with backstepping. The coupled disturbance observer is designed to estimate both the independent element and the coupled element of the external loads on each electro-hydraulic actuator. The cascade controller has the ability to compensate for the disturbance estimating, as well as guarantees the system state error convergence to a prescribed steady state level. The effectiveness of the proposed controller for the suppression of largely unknown disturbances has been demonstrated by comparative study, which implies the proposed approach can achieve better dynamic performance on the motion control of Two-Degree-of-Freedom robotic arm. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Elastic actuation for legged locomotion

    Science.gov (United States)

    Cao, Chongjing; Conn, Andrew

    2017-04-01

    The inherent elasticity of dielectric elastomer actuators (DEAs) gives this technology great potential in energy efficient locomotion applications. In this work, a modular double cone DEA is developed with reduced manufacturing and maintenance time costs. This actuator can lift 45 g of mass (5 times its own weight) while producing a stroke of 10.4 mm (23.6% its height). The contribution of the elastic energy stored in antagonistic DEA membranes to the mechanical work output is experimentally investigated by adding delay into the DEA driving voltage. Increasing the delay time in actuation voltage and hence reducing the duty cycle is found to increase the amount of elastic energy being recovered but an upper limit is also noticed. The DEA is then applied to a three-segment leg that is able to move up and down by 17.9 mm (9% its initial height), which demonstrates the feasibility of utilizing this DEA design in legged locomotion.

  17. Hydraulic hoist-press

    Energy Technology Data Exchange (ETDEWEB)

    Babayev, Z.B.; Abashev, Z.V.

    1982-01-01

    The efficiency expert of the Angrenskiy production-technological administration of the production association Sredazugol A. V. Bubnov has suggested a hydraulic hoist-press for repairing road equipment which is a device consisting of lifting mechanism, press and test stand for verifying the high pressure hoses and pumps.

  18. Modelling of Hydraulic Robot

    DEFF Research Database (Denmark)

    Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik

    1997-01-01

    This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...

  19. Water Treatment Technology - Hydraulics.

    Science.gov (United States)

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on hydraulics provides instructional materials for three competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: head loss in pipes in series, function loss in…

  20. Dielectric Barrier Discharge Plasma Actuator for Flow Control

    Science.gov (United States)

    Opaits, Dmitry, F.

    2012-01-01

    This report is Part II of the final report of NASA Cooperative Agreement contract no. NNX07AC02A. It includes a Ph.D. dissertation. The period of performance was January 1, 2007 to December 31, 2010. Part I of the final report is the overview published as NASA/CR-2012- 217654. Asymmetric dielectric barrier discharge (DBD) plasma actuators driven by nanosecond pulses superimposed on dc bias voltage are studied experimentally. This produces non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. The approach consisted of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low voltages. In view of practical applications certain questions have been also addressed, such as electrodynamic effects which accompany scaling of the actuators to real size models, and environmental effects of ozone production by the plasma actuators.

  1. Flexibility conflict?

    NARCIS (Netherlands)

    Delsen, L.W.M.

    2002-01-01

    The chapter deals with the presupposed conflict of interests between employers and employees resulting from a decoupling of operating hours and working times. It starts from the notion that both long operating hours and flexibility are relative concepts. As there is some discretion, the ultimate

  2. Flexible Consumption

    DEFF Research Database (Denmark)

    Holm Jacobsen, Peter; Pallesen, Trine

    This report presents the first findings from our qualitative study of consumer behaviour vis-à-vis flexible consumption. The main of objective of this report is to present our first round of data from Bornholm, and to assist the design of products/services designed in WP6. In the report, we adopt...

  3. Reliable hydraulic turbine governor based on identification and adaptive filtering

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, J.; Doraiswami, R.

    1986-01-01

    A scheme for improving reliable operation of a PID governor of a hydraulic turbine generating unit is proposed. The parameters of governor and actuators are identified on-line to, a) detect their anomalous behaviours, b) facilitate the calibration of the proportional integral and derivative gain settings. An adaptive filter is used to detect the lightly damped oscillations of the system. The proposed scheme was verified via simulation on the real data obtained from one of Mactaquac hydro-generating units of New Brunswick Electrical Power Commission. The simulation results show that the proposed scheme can indeed provide an accurate and rapid detection of the abnormal system operations.

  4. Fuzzy robust nonlinear control approach for electro-hydraulic flight motion simulator

    Directory of Open Access Journals (Sweden)

    Han Songshan

    2015-02-01

    Full Text Available A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command, but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simulators. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output (MISO fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decomposition of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the controller theoretically can guarantee asymptotic tracking performance in the presence of the above uncertainties, which is very important for high-accuracy tracking control of flight motion simulators. Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties.

  5. Fuzzy robust nonlinear control approach for electro-hydraulic flight motion simulator

    Institute of Scientific and Technical Information of China (English)

    Han Songshan; Jiao Zongxia; Wang Chengwen; Shang Yaoxing

    2015-01-01

    A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion sim-ulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command, but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simula-tors. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output (MISO) fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decom-position of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the control-ler theoretically can guarantee asymptotic tracking performance in the presence of the above uncer-tainties, which is very important for high-accuracy tracking control of flight motion simulators. Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties.

  6. Modular Actuators for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Rocketstar Robotics is proposing the development of a modern dual drive actuator. Rocketstar has put together numerous modern concepts for modular actuators that...

  7. Deformable mirror with thermal actuators.

    Science.gov (United States)

    Vdovin, Gleb; Loktev, Mikhail

    2002-05-01

    Low-cost adaptive optics is applied in lasers, scientific instrumentation, ultrafast sciences, and ophthalmology. These applications demand that the deformable mirrors used be simple, inexpensive, reliable, and efficient. We report a novel type of ultralow-cost deformable mirror with thermal actuators. The device has a response time of ~5 s , an actuator stroke of ~6mum , and temporal stability of ~lambda/10 rms in the visible range and can be used for correction of rather large aberrations with slow-changing amplitude.

  8. Grinding efficiency improvement of hydraulic cylinders parts for mining equipment

    Directory of Open Access Journals (Sweden)

    Korotkov Aleksandr

    2017-01-01

    Full Text Available The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms. In the course of the research work methods of machine retaining devices design were used, the scientific approaches for the selection of progressive grinding schemes were applied; theoretical and practical experience in the design and production of new constructions of grinding tools was used. As a result of this work it became possible to create a progressive construction of a machine retaining device for grinding of large parts of hydraulic cylinders, to apply an effective scheme of rotary abrasive treatment, to create and implement new design of grinding tools by means of grains with controllable shape and orientation. Implementation of the results obtained in practice will improve the quality and performance of repairing and manufacturing of mining equipment.

  9. Development of Force Reflecting Joystick for Hydraulic Excavator

    Science.gov (United States)

    Ahn, Kyoungkwan

    In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulic cylinder. Particularly pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of slave cylinder is measured and utilized as force feedback signal. This paper also proposes a novel force-reflection gain selecting algorithm based on artificial neural network. Finally a series of experiments are conducted under various load conditions using a laboratory-made one axis slave cylinder and load simulator.

  10. Design and experimental research of a novel inchworm type piezo-driven rotary actuator with the changeable clamping radius.

    Science.gov (United States)

    Zhao, Hongwei; Fu, Lu; Ren, Luquan; Huang, Hu; Fan, Zunqiang; Li, Jianping; Qu, Han

    2013-01-01

    In this paper, a novel piezo-driven rotary actuator with the changeable clamping radius is developed based on the inchworm principle. This actuator mainly utilizes three piezoelectric actuators, a flexible gripper, a clamping block, and a rotor to achieve large stroke rotation with high resolution. The design process of the flexible gripper consisting of the driving unit and the clamping unit is described. Lever-type mechanisms were used to amplify the micro clamping displacements. The amplifying factor and parasitic displacement of the lever-type mechanism in the clamping unit was analyzed theoretically and experimentally. In order to investigate the rotation characteristics of the actuator, a series of experiments was carried out. Experimental results indicate that the actuator can rotate at a speed of 77,488 μrad/s with a driving frequency of 167 Hz. The rotation resolution and maximum load torque of the actuator are 0.25 μrad and 37 N mm, respectively. The gripper is movable along the z direction based on an elevating platform, and the clamping radius can change from 10.6 mm to 25 mm. Experimental results confirm that the actuator can achieve different rotation speeds by changing the clamping radius.

  11. Large-strain, multiform movements from designable electrothermal actuators based on large highly anisotropic carbon nanotube sheets.

    Science.gov (United States)

    Li, Qingwei; Liu, Changhong; Lin, Yuan-Hua; Liu, Liang; Jiang, Kaili; Fan, Shoushan

    2015-01-27

    Many electroactive polymer (EAP) actuators use diverse configurations of carbon nanotubes (CNTs) as pliable electrodes to realize discontinuous, agile movements, for CNTs are conductive and flexible. However, the reported CNT-based EAP actuators could only accomplish simple, monotonous actions. Few actuators were extended to complex devices because efficiently preparing a large-area CNT electrode was difficult, and complex electrode design has not been carried out. In this work, we successfully prepared large-area CNT paper (buckypaper, BP) through an efficient approach. The BP is highly anisotropic, strong, and suitable as flexible electrodes. By means of artful graphic design and processing on BP, we fabricated various functional BP electrodes and developed a series of BP-polymer electrothermal actuators (ETAs). The prepared ETAs can realize various controllable movements, such as large-stain bending (>180°), helical curling (∼ 630°), or even bionic actuations (imitating human-hand actions). These functional and interesting movements benefit from flexible electrode design and the anisotropy of BP material. Owing to the advantages of low driving voltage (20-200 V), electrolyte-free and long service life (over 10000 times), we think the ETAs will have great potential applications in the actuator field.

  12. Note: A novel rotary actuator driven by only one piezoelectric actuator.

    Science.gov (United States)

    Huang, Hu; Fu, Lu; Zhao, Hongwei; Shi, Chengli; Ren, Luquan; Li, Jianping; Qu, Han

    2013-09-01

    This paper presents a novel piezo-driven rotary actuator based on the parasitic motion principle. Output performances of the rotary actuator were tested and discussed. Experiment results indicate that using only one piezoelectric actuator and simple sawtooth wave control, the rotary actuator reaches the rotation velocity of about 20,097 μrad/s when the driving voltage is 100 V and the driving frequency is 90 Hz. The actuator can rotate stably with the minimum resolution of 0.7 μrad. This paper verifies feasibility of the parasitic motion principle for applications of rotary actuators, providing new design ideas for precision piezoelectric rotary actuators.

  13. Design and performance characteristic analysis of servo valve-type water hydraulic poppet valve

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Hwan [Pusan National University, Busan (Korea, Republic of)

    2009-09-15

    For water hydraulic system control, the flow or pressure control using high-speed solenoid valve controlled by PWM control method could be a good solution for prevention of internal leakage. However, since the PWM control of on-off valves cause extensive flow and pressure fluctuation, it is difficult to control the water hydraulic actuators precisely. In this study, the servo valve-type water hydraulic valve using proportional poppet as the main valve is designed and the performance characteristics of the servo valve-type water hydraulic valve are analyzed. Furthermore, it is demonstrated through experiments that a decline in control chamber pressure that follows the change of pilot flow is caused by the occurrence of cavitation around the proportional poppet, and that fundamental characteristics of the developed valve remain unaffected by the occurrence of cavitation

  14. Miniature Low-Mass Drill Actuated by Flextensional Piezo Stack

    Science.gov (United States)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph

    2010-01-01

    Recent experiments with a flextensional piezoelectric actuator have led to the development of a sampler with a bit that is designed to produce and capture a full set of sample forms including volatiles, powdered cuttings, and core fragments. The flextensional piezoelectric actuator is a part of a series of devices used to amplify the generated strain from piezoelectric actuators. Other examples include stacks, bimorphs, benders, and cantilevers. These devices combine geometric and resonance amplifications to produce large stroke at high power density. The operation of this sampler/drill was demonstrated using a 3x2x1-cm actuator weighing 12 g using power of about 10-W and a preload of about 10 N. A limestone block was drilled to a depth of about 1 cm in five minutes to produce powdered cuttings. It is generally hard to collect volatiles from random surface profiles found in rocks and sediment, powdered cuttings, and core fragments. Toward the end of collecting volatiles, the actuator and the bit are covered with bellows-shaped shrouds to prevent fines and other debris from reaching the analyzer. A tube with a miniature bellows (to provide flexibility) is connected to the bit and directs the flow of the volatiles to the analyzer. Another modality was conceived where the hose is connected to the bellows wall directly to allow the capture of volatiles generated both inside and outside the bit. A wide variety of commercial bellows used in the vacuum and microwave industries can be used to design the volatiles capture mechanism. The piezoelectric drilling mechanism can potentially be operated in a broad temperature range from about-200 to less than 450 C. The actuators used here are similar to the actuators that are currently baselined to fly as part of the inlet funnel shaking mechanism design of MSL (Mars Science Laboratory). The space qualification of these parts gives this drill a higher potential for inclusion in a future mission, especially when considering its

  15. The kinematics of the rigid feedback linkage, the impedance of the hydraulic servomechanism and the flutter occurrence

    Directory of Open Access Journals (Sweden)

    Ioan URSU

    2012-09-01

    Full Text Available The paper brought to light a previous result of the author, used in the design of hydraulicservos actuating flight controls of the airplanes IAR 93 and IAR 99. The results highlights theimportance of the the kinematics of the rigid feedback linkage of the hydraulic servo in anaeroservoelastic frame.

  16. Education for hydraulics and pneumatics in Nara National College of Technology; Nara Kogyo Koto Senmon Gakko ni okeru yukuatsu kyoiku

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, Y. [Nara Technical Coll., Nara (Japan)

    2000-03-15

    In the electronic control engineering course, basic knowledge is taught for mechanics, electronics/electricity, control, robotics, information processing, etc., with the purpose of bringing up practical mechatronics engineers, and then, training is conducted so that the students are able to deal with these subjects comprehensively. In the subject of hydraulics and pneumatics for the special course, a lecture on hydraulic and pneumatic control is given in the second year, where structures of hydraulic and pneumatic actuators are explained as well as the principle of operation and the control method. As the related experiment, measurement of liquid viscosity coefficient and flow measurement by a Venturi tube are carried out in the fourth year of the regular course. In addition, carried out in the fifth year are the measurement of stress by trailing velocity distribution of an object and the measurement of pressure distribution around a column. As a subject for graduation theses, a mobile carrier for welfare nursing is being developed using a pneumatic actuator. Development of a suitable actuator is also being developed simultaneously. In the education of electronic control engineering, it is essential to give the students understanding of hydraulic and pneumatic actuator control centering on the role of mechatronics. (NEDO)

  17. Modelling and simulation of flight control electromechanical actuators with special focus on model architecting, multidisciplinary effects and power flows

    Institute of Scientific and Technical Information of China (English)

    Fu Jian; Jean-Charles Maré; Fu Yongling

    2017-01-01

    In the aerospace field, electromechanical actuators are increasingly being implemented in place of conventional hydraulic actuators. For safety-critical embedded actuation applications like flight controls, the use of electromechanical actuators introduces specific issues related to thermal balance, reflected inertia, parasitic motion due to compliance and response to failure. Unfortu-nately, the physical effects governing the actuator behaviour are multidisciplinary, coupled and nonlinear. Although numerous multi-domain and system-level simulation packages are now avail-able on the market, these effects are rarely addressed as a whole because of a lack of scientific approaches for model architecting, multi-purpose incremental modelling and judicious model implementation. In this publication, virtual prototyping of electromechanical actuators is addressed using the Bond-Graph formalism. New approaches are proposed to enable incremental modelling, thermal balance analysis, response to free-run or jamming faults, impact of compliance on parasitic motion, and influence of temperature. A special focus is placed on friction and compliance of the mechanical transmission with fault injection and temperature dependence. Aileron actuation is used to highlight the proposals for control design, energy consumption and thermal analysis, power net-work pollution analysis and fault response.

  18. Modelling and simulation of flight control electromechanical actuators with special focus on model architecting, multidisciplinary effects and power flows

    Directory of Open Access Journals (Sweden)

    Jian Fu

    2017-02-01

    Full Text Available In the aerospace field, electromechanical actuators are increasingly being implemented in place of conventional hydraulic actuators. For safety-critical embedded actuation applications like flight controls, the use of electromechanical actuators introduces specific issues related to thermal balance, reflected inertia, parasitic motion due to compliance and response to failure. Unfortunately, the physical effects governing the actuator behaviour are multidisciplinary, coupled and nonlinear. Although numerous multi-domain and system-level simulation packages are now available on the market, these effects are rarely addressed as a whole because of a lack of scientific approaches for model architecting, multi-purpose incremental modelling and judicious model implementation. In this publication, virtual prototyping of electromechanical actuators is addressed using the Bond-Graph formalism. New approaches are proposed to enable incremental modelling, thermal balance analysis, response to free-run or jamming faults, impact of compliance on parasitic motion, and influence of temperature. A special focus is placed on friction and compliance of the mechanical transmission with fault injection and temperature dependence. Aileron actuation is used to highlight the proposals for control design, energy consumption and thermal analysis, power network pollution analysis and fault response.

  19. Analysis of the sweeped actuator line method

    Directory of Open Access Journals (Sweden)

    Nathan Jörn

    2015-01-01

    Full Text Available The actuator line method made it possible to describe the near wake of a wind turbine more accurately than with the actuator disk method. Whereas the actuator line generates the helicoidal vortex system shed from the tip blades, the actuator disk method sheds a vortex sheet from the edge of the rotor plane. But with the actuator line come also temporal and spatial constraints, such as the need for a much smaller time step than with actuator disk. While the latter one only has to obey the Courant-Friedrichs-Lewy condition, the former one is also restricted by the grid resolution and the rotor tip-speed. Additionally the spatial resolution has to be finer for the actuator line than with the actuator disk, for well resolving the tip vortices. Therefore this work is dedicated to examining a method in between of actuator line and actuator disk, which is able to model the transient behaviour, such as the rotating blades, but which also relaxes the temporal constraint. Therefore a larger time-step is used and the blade forces are swept over a certain area. The main focus of this article is on the aspect of the blade tip vortex generation in comparison with the standard actuator line and actuator disk.

  20. Design of a piezoelectric rotation actuator

    NARCIS (Netherlands)

    Holterman, J.; de Vries, Theodorus J.A.; Babakhani, B.; Brouwer, Dannis Michel

    2012-01-01

    In order to facilitate active damping within a linear motion system, a self-sensing piezoelectric rotation actuator has been designed. The rotation actuator consists of two piezoelectric stacks that function as linear actuators, embedded in a mechanical interface with several elastic elements, thus

  1. Carbon nanotube-polymer composite actuators

    Science.gov (United States)

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  2. Experimental identification of piezo actuator characteristic

    Directory of Open Access Journals (Sweden)

    Ľ. Miková

    2015-01-01

    Full Text Available This paper deals with piezoelectric material, which can be used as actuator for conversion of electrical energy to mechanical work. Test equipment has been developed for experimental testing of the piezoactuators. Piezoactivity of this actuator has non-linear characteristic. This type of actuator is used for in-pipe mechanism design.

  3. Flexible isotopy classification of flexible links

    OpenAIRE

    Björklund, Johan

    2012-01-01

    In this paper we define and study flexible links and flexible isotopy in projective space. Flexible links are meant to capture the topological properties of real algebraic links. We classify all flexible links up to flexible isotopy using Ekholms interpretation of Viros encomplexed writhe.

  4. Two SMA-Actuated Miniature Mechanisms

    Science.gov (United States)

    Willey, Cliff E.

    2005-01-01

    The figures depict two miniature mechanisms actuated by strips made of shape-memory alloy (SMA). A typical SMA is a nickel-titanium alloy known by the trade name "Flexinol" or "Nitinol." In preparation for a typical application, a suitably sized and shaped piece of an SMA is deformed by a predetermined amount at the lower of two operating temperatures, then mounted in a mechanism. When stroking of the mechanism in one direction is desired, the piece of SMA is heated above a transition temperature to make it return to the "remembered" undeformed state. When stroking of the mechanism in the opposite direction is desired, the SMA is cooled below the transition temperature to make it return to the deformed state. Also, the SMA alloy chosen for a specific application is one that has a transition temperature somewhat above the ambient temperature, so that stroking in one direction or the opposite direction can be achieved by heating the SMA, or refraining from heating the SMA, respectively, above the transition temperature. In the present mechanisms as in typical other SMA mechanisms, the heating is effected by electric currents applied via electrical contacts at the ends of the SMA strips. The purpose served by the mechanism of Figure 1 is to lock or release a flexible latch attachment. In preparation for use in this mechanism, two initially straight SMA strips are deformed into curved springs that, when mounted in the mechanism at ambient temperature, clamp the knob at the lower end of the flexible latch attachment. When heated above their transition temperature by an electric current, the SMA strips return to their original straight configuration, thereby releasing the knob. This mechanism is redundant in the sense that as long as at least one of the two SMA strips straightens when commanded to do so, the knob is released. The mechanism of Figure 2 is suited to any of a variety of applications in which there are requirements for a small mechanism that affords

  5. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...... flexible commoditization that more commonly is touted as tearing social relations apart. By interrogating a keenly debated contemporary work regime through an approach to sociality rooted in a rich and distinct anthropological legacy, the volume also makes a novel contribution to the anthropological...

  6. Multilayer Piezoelectric Stack Actuator Characterization

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  7. Explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den Dennis Micha

    2008-01-01

    Microactuators are key components in numerous microsystems, and in many applications strong and fast microactuators are required. The principles used to generate forces in the current actuators are not capable of fulfilling both requirements at the same time, so new principles have to be investigate

  8. Compliant actuation of rehabilitation robots

    NARCIS (Netherlands)

    Vallery, Heike; Veneman, Jan; Asseldonk, van Edwin; Ekkelenkamp, Ralf; Buss, Martin; Kooij, van der Herman

    2008-01-01

    This article discusses the pros and cons of compliant actuation for rehabilitation robots on the example of LOPES, focusing on the cons. After illustrating the bandwidth limitations, a new result has been derived: if stability in terms of passivity of the haptic device is desired, the renderable sti

  9. Piezoelectric multilayer actuator life test.

    Science.gov (United States)

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  10. Development and Analysis of Bending Actuator Using McKibben Artificial Muscle

    Science.gov (United States)

    Zhao, Feifei; Dohta, Shujiro; Akagi, Tetsuya

    Recent years, the number of nuclear families is rapidly growing. So the development of a human-friendly-robot which can take care of human daily life is strongly desired. This robot has to work just like a human, so, it is needed to have a dexterous soft hand in the robot. Therefore, we have developed an artificial soft gripper. This robot hand which has five fingers is made of silicone rubber. We also developed the hand which could be used to achieve several works just like a human hand. For example, it can grasp some objects that have the different shape and stiffness. Since it is made of silicone rubber, there is little damage to the object. However, the finger could not generate a larger force, less than 3N. In addition, it needs a skill and time to make the finger. In this study, we proposed and tested a bending actuator that could be easily constructed by putting the McKibben artificial muscle into the flexible tube. We also investigated the generated force and bending angle of the actuator. As a result, the generated force of the actuator was improved about 8.5 times as large as previous one. We also improved the bending actuator by changing the tube and the slit of the flexible tube. And the analytical model for the bending actuator was proposed and the calculated results were compared with the experimental ones.

  11. Intelligent Control of Flexible-Joint Robotic Manipulators

    Science.gov (United States)

    Colbaugh, R.; Gallegos, G.

    1997-01-01

    This paper considers the trajectory tracking problem for uncertain rigid-link. flexible.joint manipulators, and presents a new intelligent controller as a solution to this problem. The proposed control strategy is simple and computationally efficient, requires little information concerning either the manipulator or actuator/transmission models and ensures uniform boundedness of all signals and arbitrarily accurate task-space trajectory tracking.

  12. Analysis of the concurrent operation of excavator actuating mechanisms as the determining factor in increasing its productivity

    Directory of Open Access Journals (Sweden)

    Lenivtsev Aleksandr

    2017-01-01

    Full Text Available The most effective methods of organizing construction work are complex mechanization and automation of construction. Complex mechanization allows selecting the machines participating in the construction process according to their productivity. In this regard, it is necessary to take into account the structural features of construction machines that affect the overall pace of work. In order to shorten the cycle time, the design of a modern excavator’s hydraulic system ensures the combined operation of two degrees of mobility in pairs: platform-boom, boom-arm, and arm-bucket. When designing and creating a system for automatic control of excavator actuating mechanisms, it is necessary to take into account the interrelation and mutual influence of hydraulic drives when working together from a source of limited power, the pump station of an excavator. Such a time combination of operations is possible when carrying out transportation to move the bucket to load and unload, while soil excavation is performed by turning the handle or bucket, and in these conditions, a large load of the feeding power station does not allow combining these operations. The paper presents a structural diagram of the concurrent operation of two hydraulic excavator actuators, which reflects the existence of connections between the hydraulic motors of the actuators.

  13. Characterization and Testing of an Electrorheological Fluid Valve for Control of ERF Actuators

    Directory of Open Access Journals (Sweden)

    Quang-Anh Nguyen

    2015-06-01

    Full Text Available Previous studies of electrorheological fluids (ERFs were motivated by brake, clutch, damping, haptic and resistive applications, but never motivated towards developing an ERF based-hydraulic rotary actuator. One design to make such an actuator is to use ERF-based valves. To fully understand the performance of such an actuator, it is imperative to study ERF valves. For this reason, this paper presents a summary of design considerations for creating ERF-based actuators, an ERF-based valve design for an ERF actuator and a new experimental test-bed to obtain viscosity and yield characteristics of the ERF at flow rates as low as 0.049 L/min, an order of magnitude lower than industrial rheometers. The new test-bed successfully measured the dynamic viscosity of the ERF to be at 0.6 Pa-s for low flow rates and 0.2 Pa-s for higher flow rates. The presented valve design can successfully resist 1 MPa of fluid pressure, which is an operation mode higher than any haptic and damping applications in the literature. The experiments also shows that higher flow rates negatively affect the ERF’s yield characteristics for the first time in a situation where the ERF valve completely blocks flow. When the flow rates are increased, the response time to a fully-closed valve increases, the effective yield capability of the ERF decreases and the conductivity of the ERF increases.

  14. A Resistivity Gradient Piezoelectric FGM Actuator

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A resistivity gradient actuator based on lead zirconate titanate ceramics was successfully developed and the bending deflections up to 140 μm were obtained. The actuator material was a matrix of PZT ceramic into which smooth gradient of piezoelectric activity was introduced. The application of an electric field then causes the actuator to bend due to differential strains induced by the piezoelectric effect. The resistivity gradient of the actuator was achieved by doping PZT with suitable donor and acceptor dopants. PZT powder was modified and synthesized by using two stage powder fabrication method. The actuator was fabricated by uniaxial pressing followed by isostatic pressing with two layers of different resistivities.

  15. Undular Hydraulic Jump

    Directory of Open Access Journals (Sweden)

    Oscar Castro-Orgaz

    2015-04-01

    Full Text Available The transition from subcritical to supercritical flow when the inflow Froude number Fo is close to unity appears in the form of steady state waves called undular hydraulic jump. The characterization of the undular hydraulic jump is complex due to the existence of a non-hydrostatic pressure distribution that invalidates the gradually-varied flow theory, and supercritical shock waves. The objective of this work is to present a mathematical model for the undular hydraulic jump obtained from an approximate integration of the Reynolds equations for turbulent flow assuming that the Reynolds number R is high. Simple analytical solutions are presented to reveal the physics of the theory, and a numerical model is used to integrate the complete equations. The limit of application of the theory is discussed using a wave breaking condition for the inception of a surface roller. The validity of the mathematical predictions is critically assessed using physical data, thereby revealing aspects on which more research is needed

  16. Dielectric elastomer actuators for facial expression

    Science.gov (United States)

    Wang, Yuzhe; Zhu, Jian

    2016-04-01

    Dielectric elastomer actuators have the advantage of mimicking the salient feature of life: movements in response to stimuli. In this paper we explore application of dielectric elastomer actuators to artificial muscles. These artificial muscles can mimic natural masseter to control jaw movements, which are key components in facial expressions especially during talking and singing activities. This paper investigates optimal design of the dielectric elastomer actuator. It is found that the actuator with embedded plastic fibers can avert electromechanical instability and can greatly improve its actuation. Two actuators are then installed in a robotic skull to drive jaw movements, mimicking the masseters in a human jaw. Experiments show that the maximum vertical displacement of the robotic jaw, driven by artificial muscles, is comparable to that of the natural human jaw during speech activities. Theoretical simulations are conducted to analyze the performance of the actuator, which is quantitatively consistent with the experimental observations.

  17. Chopping of near- and mid-infrared radiation using a curled electrostatic MEMS actuator

    Science.gov (United States)

    Dausch, David E.; Goodwin, Scott H.; Exarhos, Gregory J.

    2003-09-01

    An electrostatic MEMS actuator known as the "Artificial Eyelid" can be used as a micromechanical chopper for IR detectors. The actuator structure consists of a curled polymer/metal film stack which is microfabricated and released from an IR transparent substrate. The film stack is uncurled by applying an electric field between the curled film and the transparent fixed electrode on the substrate. These flexible film actuators can act as IR choppers, providing transmission of radiation to the sensor elements when open (curled) and reflection when closed (uncurled). Arrays of actuators were fabricated on ITO-coated glass substrates and ranged in size from 4 x 4 mm to 7.5 x 15 mm with individual elements ranging from 250 to 500 μm on a side. Actuation for devices with average radius of curvature of 120 μ was consistently achieved at 150-170 V operation with 98-100% of the elements functioning and long lifetimes. IR chopper characteristics were measured using a blackbody source and pyroelectric detector by applying sine and square wave voltage to the actuators at a frequency of 30 Hz. The capability of the artificial eyelid for chopping near- and mid-IR radiation, including future fabrication of devices using NiCo2O4 or NiRh2O4 films for IR transparent electrodes, will be discussed.

  18. Frequency-weighted feedforward control for dynamic compensation in ionic polymer-metal composite actuators

    Science.gov (United States)

    Shan, Yingfeng; Leang, Kam K.

    2009-12-01

    Ionic polymer-metal composites (IPMCs) are innovative materials that offer combined sensing and actuating ability in lightweight and flexible package. IPMCs have been exploited in robotics and a wide variety of biomedical devices, for example, as sensors for teleoperation, as actuators for positioning in active endoscopy, as fins for propelling aquatic robots, and as an injector for drug delivery. In the actuation mode, one of the main challenges is precise position control. In particular, IPMC actuators exhibit relaxation behavior and nonlinearities; and at relatively high operating frequencies dynamic effects limit accuracy and positioning bandwidth. A frequency-weighted feedforward controller is designed to account for the IPMC's structural dynamics to enable fast positioning. The control method is applied to a custom-made Nafion-based IPMC actuator. The controller takes into account the magnitude of the control input to avoid generating excessively large voltages which can damage the IPMC actuator. To account for unmodeled effects not captured by the dynamics model, a feedback controller is integrated with the feedforward controller. Experimental results show a significant improvement in the tracking performance when feedforward control is used. For instance, the feedforward controller shows over 75% reduction in the tracking error compared to the case without feedforward compensation. Finally, the integrated feedforward and feedback control system reduces the tracking error to less than 10% for tracking an 18-Hz triangle-like trajectory. Some of the advantages of feedforward control as well as its limitations are also discussed.

  19. A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

    Science.gov (United States)

    Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

    2008-03-01

    This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments.

  20. Engineering Design Tools for Shape Memory Alloy Actuators: CASMART Collaborative Best Practices and Case Studies

    Science.gov (United States)

    Wheeler, Robert W.; Benafan, Othmane; Gao, Xiujie; Calkins, Frederick T; Ghanbari, Zahra; Hommer, Garrison; Lagoudas, Dimitris; Petersen, Andrew; Pless, Jennifer M.; Stebner, Aaron P.; Turner, Travis L.

    2016-01-01

    The primary goal of the Consortium for the Advancement of Shape Memory Alloy Research and Technology (CASMART) is to enable the design of revolutionary applications based on shape memory alloy (SMA) technology. In order to help realize this goal and reduce the development time and required experience for the fabrication of SMA actuation systems, several modeling tools have been developed for common actuator types and are discussed herein along with case studies, which highlight the capabilities and limitations of these tools. Due to their ability to sustain high stresses and recover large deformations, SMAs have many potential applications as reliable, lightweight, solid-state actuators. Their advantage over classical actuators can also be further improved when the actuator geometry is modified to fit the specific application. In this paper, three common actuator designs are studied: wires, which are lightweight, low-profile, and easily implemented; springs, which offer actuation strokes upwards of 200 at reduced mechanical loads; and torque tubes, which can provide large actuation forces in small volumes and develop a repeatable zero-load actuation response (known as the two-way shape memory effect). The modeling frameworks, which have been implemented in the design tools, are developed for each of these frequently used SMA actuator types. In order to demonstrate the versatility and flexibility of the presented design tools, as well as validate their modeling framework, several design challenges were completed. These case studies include the design and development of an active hinge for the deployment of a solar array or foldable space structure, an adaptive solar array deployment and positioning system, a passive air temperature controller for regulation flow temperatures inside of a jet engine, and a redesign of the Corvette active hatch, which allows for pressure equalization of the car interior. For each of the presented case studies, a prototype or proof

  1. Magneto-mechanical actuation model for fin-based locomotion

    CERN Document Server

    Carbajal, Juan Pablo; 10.2495/DN100331

    2011-01-01

    In this paper, we report the results from the analysis of a numerical model used for the design of a magnetic linear actuator with applications to fin-based locomotion. Most of the current robotic fish generate bending motion using rotary motors which implies at least one mechanical conversion of the motion. We seek a solution that directly bends the fin and, at the same time, is able to exploit the magneto-mechanical properties of the fin material. This strong fin-actuator coupling blends the actuator and the body of the robot, allowing cross optimization of the system's elements. We study a simplified model of an elastic element, a spring-mass system representing a flexible fin, subjected to nonlinear forcing, emulating magnetic interaction. The dynamics of the system is studied under unforced and periodic forcing conditions. The analysis is focused on the limit cycles present in the system, which allows the periodic bending of the fin and the generation of thrust. The frequency, maximum amplitude and cente...

  2. Experimental-based Modelling and Simulation of Water Hydraulic Mechatronics Test Facilities for Motion Control and Operation in Environmental Sensitive Applications` Areas

    DEFF Research Database (Denmark)

    Conrad, Finn; Pobedza, J.; Sobczyk, A.

    2003-01-01

    The paper presents experimental-based modelling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions includes results from on-going research projects on fluid power and mechatronics based on tap water hydraulic...... proportional valves and servo actuators for motion control and power transmission undertaken in co-operation by Technical University, DTU and Cracow University of Technology, CUT. The results of this research co-operation include engineering design and test of simulation models compared with two mechatronic...

  3. Output feedback control for a class of nonlinear systems with actuator degradation and sensor noise.

    Science.gov (United States)

    Ai, Weiqing; Lu, Zhenli; Li, Bin; Fei, Shumin

    2016-11-01

    This paper investigates the output feedback control problem of a class of nonlinear systems with sensor noise and actuator degradation. Firstly, by using the descriptor observer approach, the origin system is transformed into a descriptor system. On the basis of the descriptor system, a novel Proportional Derivative (PD) observer is developed to asymptotically estimate sensor noise and system state simultaneously. Then, by designing an adaptive law to estimate the effectiveness of actuator, an adaptive observer-based controller is constructed to ensure that system state can be regulated to the origin asymptotically. Finally, the design scheme is applied to address a flexible joint robot link problem.

  4. NUMERICAL MODELING OF MULTICYLINDER ELECTRO-HYDRAULIC SYSTEM AND CONTROLLER DESIGN FOR SHOCK TEST MACHINE

    Institute of Scientific and Technical Information of China (English)

    CHU Deying; ZHANG Zhiyi; WANG Gongxian; HUA Hongxing

    2007-01-01

    A high fidelity dynamic model of a high-energy hydraulically-actuated shock test machine for heavy weight devices is presented to satisfy the newly-built shock resistance standard and simulate the actual underwater explosion environments in laboratory as well as increase the testing capability of shock test machine. In order to produce the required negative shock pulse in the given time duration, four hydraulic actuators are utilized. The model is then used to formulate an advanced feedforward controller for the system to produce the required negative waveform and to address the motion synchronization of the four cylinders. The model provides a safe and easily controllable way to perform a "virtual testing" before starting potentially destructive tests on specimen and to predict performance of the system. Simulation results have demonstrated the effectiveness of the controller.

  5. Bifurcation Control of an Electrostatically-Actuated MEMS Actuator with Time-Delay Feedback

    Directory of Open Access Journals (Sweden)

    Lei Li

    2016-10-01

    Full Text Available The parametric excitation system consisting of a flexible beam and shuttle mass widely exists in microelectromechanical systems (MEMS, which can exhibit rich nonlinear dynamic behaviors. This article aims to theoretically investigate the nonlinear jumping phenomena and bifurcation conditions of a class of electrostatically-driven MEMS actuators with a time-delay feedback controller. Considering the comb structure consisting of a flexible beam and shuttle mass, the partial differential governing equation is obtained with both the linear and cubic nonlinear parametric excitation. Then, the method of multiple scales is introduced to obtain a slow flow that is analyzed for stability and bifurcation. Results show that time-delay feedback can improve resonance frequency and stability of the system. What is more, through a detailed mathematical analysis, the discriminant of Hopf bifurcation is theoretically derived, and appropriate time-delay feedback force can make the branch from the Hopf bifurcation point stable under any driving voltage value. Meanwhile, through global bifurcation analysis and saddle node bifurcation analysis, theoretical expressions about the system parameter space and maximum amplitude of monostable vibration are deduced. It is found that the disappearance of the global bifurcation point means the emergence of monostable vibration. Finally, detailed numerical results confirm the analytical prediction.

  6. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...

  7. Decentralized vibration control of a multi-link flexible robotic manipulator using smart piezoelectric transducers

    Science.gov (United States)

    Halim, Dunant; Luo, Xi; Trivailo, Pavel M.

    2014-11-01

    The work in this paper is aimed to investigate the use of a decentralized control system for suppressing vibration of a multi-link flexible robotic manipulator using embedded smart piezoelectric transducers. To achieve this, a non-linear dynamic model of a flexible robotic manipulator with smart piezoelectric actuators/sensors, is developed based on the co-rotational finite element method. The method incorporates multiple co-ordinate (co-rotational) systems which rotate and translate with each element, so that the geometric non-linearity present in rotating manipulator system can be dealt with efficiently. The placement of piezoelectric actuators and sensors over the flexible links are considered for the application of decentralized control system. A numerical study shows that the developed co-rotational finite element method can be utilized to investigate the piezoelectric actuator/sensor placement and vibration control performances for a multi-link flexible manipulator undertaking complicated motion.

  8. Implementation of a Fuzzy TSK Controller for a Flexible Joint Robot

    Directory of Open Access Journals (Sweden)

    M. E. Akbari

    2012-01-01

    Full Text Available This paper proposes a fuzzy TSK controller to control a rotary flexible joint manipulator. The flexibility of joint is performed by means of a solenoid nonlinear spring, which is connected between actuator output and joint input in a bilateral connection form to transfer the produced torque; also the smooth model of frictions is used for modeling the dynamics of flexible manipulator. The effect of coulomb friction and also gearbox backlashes is decreased by a pulsation signal as an extra voltage that is added to the control voltage of actuator. Actuator dynamics is modeled by consideration of saturation mode of armature current. Experimental results demonstrate that the proposed controller has an ability to control flexible joint manipulator with a good performance.

  9. Actuators of 3-element unimorph deformable mirror

    Science.gov (United States)

    Fu, Tianyang; Ning, Yu; Du, Shaojun

    2016-10-01

    Kinds of wavefront aberrations exist among optical systems because of atmosphere disturbance, device displacement and a variety of thermal effects, which disturb the information of transmitting beam and restrain its energy. Deformable mirror(DM) is designed to adjust these wavefront aberrations. Bimorph DM becomes more popular and more applicable among adaptive optical(AO) systems with advantages in simple structure, low cost and flexible design compared to traditional discrete driving DM. The defocus aberration accounted for a large proportion of all wavefront aberrations, with a simpler surface and larger amplitude than others, so it is very useful to correct the defocus aberration effectively for beam controlling and aberration adjusting of AO system. In this study, we desired on correcting the 3rd and 10th Zernike modes, analyze the characteristic of the 3rd and 10th defocus aberration surface distribution, design 3-element actuators unimorph DM model study on its structure and deformation principle theoretically, design finite element models of different electrode configuration with different ring diameters, analyze and compare effects of different electrode configuration and different fixing mode to DM deformation capacity through COMSOL finite element software, compare fitting efficiency of DM models to the 3rd and 10th Zernike modes. We choose the inhomogeneous electrode distribution model with better result, get the influence function of every electrode and the voltage-PV relationship of the model. This unimorph DM is suitable for the AO system with a mainly defocus aberration.

  10. Robust Force Control of a 6-Link Electro-Hydraulic Manipulator

    Science.gov (United States)

    Ahn, Kyoungkwan; Yokota, Shinichi

    Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. This maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system using electro-hydraulic manipulator because hydraulic manipulators have the advantage of electric insulation and power/mass density. Meanwhile an electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the autonomous assembly tasks using hydraulic manipulators. In this paper, the robust force control of a 6-link electro-hydraulic manipulator system used in the real maintenance task of active electic line is examined in detail. A nominal model for the system is obtained from experimental frequency responses of the system, and the deviation of the manipulator system from the nominal model is derived by a multiplicative uncertainty. Robust disturbance observers for force control are designed using this information in an H∞ framework, and implemented on the two different setups. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved even if the stiffness of environment and the shape of wall change.

  11. HYDRAULIC ACTIVE GUIDE ROLLER SYSTEM FOR HIGH-SPEED ELEVATOR BASED ON FUZZY CONTROLLER

    Institute of Scientific and Technical Information of China (English)

    FENG Yonghui; ZHANG Jianwu

    2007-01-01

    Increase of elevator speed brings about amplified vibrations of high-speed elevator. In order to reduce the horizontal vibrations of high-speed elevator, a new type of hydraulic active guide roller system based on fuzzy logic controller is developed. First the working principle of the hydraulic guide system is introduced, then the dynamic model of the horizontal vibrations for elevator cage with active guide roller system and the mathematical model of the hydraulic system are given. A fuzzy logic controller for the hydraulic system is designed to control the hydraulic actuator. To improve the control performance, preview compensation for the controller is provided. Finally, simulation and experiments are executed to verify the hydraulic active guide roller system and the control strategy. Both the simulation and experimental results indicate that the hydraulic active guide roller system can reduce the horizontal vibrations of the elevator effectively and has better effects than the passive one, and the fuzzy logic controller with preview compensation can give superior control performance.

  12. Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve

    Directory of Open Access Journals (Sweden)

    C. Velescu

    2015-01-01

    Full Text Available We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids’ motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i velocity and pressure distributions, (ii average velocity, (iii volume flow rate of the liquid, (iv pressures difference, and (v radial clearance.

  13. Role of Pectoral Fin Flexibility in Robotic Fish Performance

    Science.gov (United States)

    Bazaz Behbahani, Sanaz; Tan, Xiaobo

    2017-08-01

    Pectoral fins play a vital role in the maneuvering and locomotion of fish, and they have become an important actuation mechanism for robotic fish. In this paper, we explore the effect of flexibility of robotic fish pectoral fins on the robot locomotion performance and mechanical efficiency. A dynamic model for the robotic fish is presented, where the flexible fin is modeled as multiple rigid elements connected via torsional springs and dampers. Blade element theory is used to capture the hydrodynamic force on the fin. The model is validated with experimental results obtained on a robotic fish prototype, equipped with 3D-printed fins of different flexibility. The model is then used to analyze the impacts of fin flexibility and power/recovery stroke speed ratio on the robot swimming speed and mechanical efficiency. It is found that, in general, flexible fins demonstrate advantages over rigid fins in speed and efficiency at relatively low fin-beat frequencies, while rigid fins outperform flexible fins at higher frequencies. For a given fin flexibility, the optimal frequency for speed performance differs from the optimal frequency for mechanical efficiency. In addition, for any given fin, there is an optimal power/recovery stroke speed ratio, typically in the range of 2-3, that maximizes the speed performance. Overall, the presented model offers a promising tool for fin flexibility and gait design, to achieve speed and efficiency objectives for robotic fish actuated with pectoral fins.

  14. PMN-PT piezoelectric-electrostrictive bi-layer composite actuators

    Science.gov (United States)

    Ngernchuklin, Piyalak

    In the past few decades, significant advances have been achieved to replace the conventional actuators, including hydraulic, shape memory alloy, electromagnetic and linear induction, with piezoelectric actuators since they are light weight and small in size, have precision positioning capabilities, offer a wide range of generative force, consume less power, and provide higher durability and reliability. The strain produced by bulk polycrystalline piezoelectric ceramics and single crystals are typically in the range of 0.1 to 1%, respectively, which is still low for many applications. Therefore, various strain amplification designs including multilayer, bimorph, unimorph, flextensional actuators (Moonie and cymbal), co-fired and functionally graded ceramics have been proposed to enhance the displacement. In this investigation, Piezoelectric/Electrostrictive Bi-Layer Monolithic Composites (PE-MBLC) were fabricated by co-pressing and co-sintering of the piezoelectric (PMN-PT 65/35: P) and electrostrictive (PMN/PT 90/10: E) powders. Flat and dome shaped of PE-MBLCs were obtained by optimizing processing conditions such as pressing pressure and sintering temperature. In addition, poling conditions of bilayer composite actuators were thoroughly studied to maximize their electromechanical properties. It was found that composites had lower d33eff and Keff values than the calculated values. This was attributed to a significant difference between relative permittivities of P and E materials as well as the presence of induced stresses in both P and E layers after sintering that hindered domain switching within piezoelectric layer during poling. The shape change (planar to dome), electromechanical properties, and actuation performance of PE-MBLC actuators were examined as a function of volume percent of piezoelectric phase. The highest displacement ˜15 mum was obtained from PE-MBLC actuator with 50 volume % piezoelectric phase due to the transverse strain response of

  15. Piezoelectric step-motion actuator

    Science.gov (United States)

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  16. Electrical actuators applications and performance

    CERN Document Server

    De Fornel, Bernard

    2013-01-01

    This helpful resource covers a large range of information regarding electrical actuators. In particular, robustness, a very problematic issue, is fully explored in a dedicated chapter. The text also deals with he estimate of non-measurable mechanical variables by examining the estimate of load moment, then observation of the positioning of a command without mechanical sensor. Finally, it examines the conditions needed to measure variables and real implementation of numerical algorithms. This is a key working resource for electrical engineers.

  17. Photocontrollable liquid-crystalline actuators

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Haifeng [Top Runner Incubation Center for Academia-Industry Fusion and Department of Materials and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188 (Japan); Ikeda, Tomiki [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-11, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2011-05-17

    Coupling photochromic molecules with liquid crystalline (LC) materials enables one to reversibly photocontrol unique LC features such as phase transition, photoalignment, and molecular cooperative motion. LC elastomers show photomechanical and photomobile properties, directly converting light energy into mechanical energy. In well-defined LC block copolymers, regular patternings of nanostructures in macroscopic scales are fabricated by photo-manipulation of LC actuators. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. An Innovative Shape Memory Actuator

    Directory of Open Access Journals (Sweden)

    Cappellini Valter

    2016-01-01

    Full Text Available The work describes a NiTi linear actuator. This material is able to realize a contraction with heating produced through Joule effect. Then a cooling of the active device is realized with forced air. Finally the lengthening is realized with another active element. The particular structure of the geometry allows for an increment of reliability, because the electrical connections are mechanically stabilized and the active elements are compelled to avoid undesired electrical contacts through an insulated cylindrical core.

  19. Simulating Magneto-Aerodynamic Actuator

    Science.gov (United States)

    2007-12-20

    2005. 19. Boeuf, J.P., Lagmich, Y., Callegari, Th., and Pitchford , L.C., Electro- hydrodynamic Force and Acceleration in Surface Discharge, AIAA 2006...Plasmadynamics and Laser Award, 2004 AFRL Point of Contact Dr. Donald B. Paul , AFRL/VA WPAFB, OH 937-255-7329, met weekly. Dr. Alan Garscadden, AFRL/PR...validating database for numerical simulation of magneto-aerodynamic actuator for hypersonic flow control. Points of contact at the AFRL/VA are Dr. D. Paul

  20. Surface actuation of smart nanoshutters.

    Science.gov (United States)

    Morsch, S; Schofield, W C E; Badyal, J P S

    2010-07-20

    Patterned polymer brush surfaces have been fabricated using the molecular scratchcard lithography technique, where a functional top nanolayer (acting also as a resist) is selectively removed using a scanning probe tip to expose underlying atom-transfer radical polymerization (ATRP) initiator sites. The lateral spreading of grafted polymer brush patterns across the adjacent functional resist surface can be reversibly actuated via solvent exposure. Effectively, this methodology provides a means for hiding/unveiling functional surfaces on the nanoscale.