Full Text Available The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.
Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.
Gondhalekar, Vijay; Downer, James R.; Eisenhaure, David B.; Hockney, Richard L.; Johnson, Bruce G.
The authors describe two ongoing research efforts directed at developing advanced spacecraft momentum control flywheels. The first effort is directed at developing low-noise momentum wheels through the use of magnetic bearings. The second effort is directed at demonstrating critical subcomponents of an integrated power and attitude control system (IPACS) that stores energy as kinetic energy in mechanical rotors with the accompanying angular momentum available for attitude control of the spacecraft. The authors describe a ground experiment that was designed to demonstrate an energy storage capability of 1 kWh at a 40 Wh/kg energy density and a 1 kW electrical generation capacity at 85 percent round-trip efficiency and that will allow single-degree-of-freedom gimballing to quantify experimentally the bearing power requirements for processing the flywheel.
Robertson, Brent; Placanica, Sam; Morgenstern, Wendy
This paper presents an overview of the Tropical Rainfall Measuring Mission (TRMM) Attitude Control System (ACS) along with detailed in-flight performance results for each operational mode. The TRMM spacecraft is an Earth-pointed, zero momentum bias satellite launched on November 27, 1997 from Tanegashima Space Center, Japan. TRMM is a joint mission between NASA and the National Space Development Agency (NASDA) of Japan designed to monitor and study tropical rainfall and the associated release of energy. Launched to provide a validation for poorly known rainfall data sets generated by global climate models, TRMM has demonstrated its utility by reducing uncertainties in global rainfall measurements by a factor of two. The ACS is comprised of Attitude Control Electronics (ACE), an Earth Sensor Assembly (ESA), Digital Sun Sensors (DSS), Inertial Reference Units (IRU), Three Axis Magnetometers (TAM), Coarse Sun Sensors (CSS), Magnetic Torquer Bars (MTB), Reaction Wheel Assemblies (RWA), Engine Valve Drivers (EVD) and thrusters. While in Mission Mode, the ESA provides roll and pitch axis attitude error measurements and the DSS provide yaw updates twice per orbit. In addition, the TAM in combination with the IRU and DSS can be used to provide pointing in a contingency attitude determination mode which does not rely on the ESA. Although the ACS performance to date has been highly successful, lessons were learned during checkout and initial on-orbit operation. This paper describes the design, on-orbit checkout, performance and lessons learned for the TRMM ACS.
Andrews, S. F.; Campbell, C. E.; Ericsson-Jackson, A. J.; Markley, F. L.; ODonnell, J. R., Jr.
The Microwave Anisotropy Probe (MAP) is a follow-on to the Differential Microwave Radiometer (DMR) instrument on the Cosmic Background Explorer (COBE) spacecraft. The MAP spacecraft will perform its mission in a Lissajous orbit around the Earth-Sun L(sub 2) Lagrange point to suppress potential instrument disturbances. To make a full-sky map of cosmic microwave background fluctuations, a combination fast spin and slow precession motion will be used. MAP requires a propulsion system to reach L(sub 2), to unload system momentum, and to perform stationkeeping maneuvers once at L(sub 2). A minimum hardware, power and thermal safe control mode must also be provided. Sufficient attitude knowledge must be provided to yield instrument pointing to a standard deviation of 1.8 arc-minutes. The short development time and tight budgets require a new way of designing, simulating, and analyzing the Attitude Control System (ACS). This paper presents the design and analysis of the control system to meet these requirements.
Attitude stability augmentation control system with a lower cost need to be designed so that MUH (Mini Unmanned Helicopter) can adapt to different types of geographic environment and fly steadily although the weather may be bad. Attitude feedback was calculated mainly by filtering estimation within attitude acquisition module in this system. Stability augmentation can be improved mainly by PI. This paper will depict running principle and designing process of MUH attitude stability augmentation control system and algorithm that is considered as an important part in this system.
Chak, Yew-Chung; Varatharajoo, Renuganth
Many spacecraft attitude control systems today use reaction wheels to deliver precise torques to achieve three-axis attitude stabilization. However, irrecoverable mechanical failure of reaction wheels could potentially lead to mission interruption or total loss. The electrically-powered Solar Array Drive Assemblies (SADA) are usually installed in the pitch axis which rotate the solar arrays to track the Sun, can produce torques to compensate for the pitch-axis wheel failure. In addition, the attitude control of a flexible spacecraft poses a difficult problem. These difficulties include the strong nonlinear coupled dynamics between the rigid hub and flexible solar arrays, and the imprecisely known system parameters, such as inertia matrix, damping ratios, and flexible mode frequencies. In order to overcome these drawbacks, the adaptive Jacobian tracking fuzzy control is proposed for the combined attitude and sun-tracking control problem of a flexible spacecraft during attitude maneuvers in this work. For the adaptation of kinematic and dynamic uncertainties, the proposed scheme uses an adaptive sliding vector based on estimated attitude velocity via approximate Jacobian matrix. The unknown nonlinearities are approximated by deriving the fuzzy models with a set of linguistic If-Then rules using the idea of sector nonlinearity and local approximation in fuzzy partition spaces. The uncertain parameters of the estimated nonlinearities and the Jacobian matrix are being adjusted online by an adaptive law to realize feedback control. The attitude of the spacecraft can be directly controlled with the Jacobian feedback control when the attitude pointing trajectory is designed with respect to the spacecraft coordinate frame itself. A significant feature of this work is that the proposed adaptive Jacobian tracking scheme will result in not only the convergence of angular position and angular velocity tracking errors, but also the convergence of estimated angular velocity to
Eisenhaure, David B.; Bechtel, Robert; Hockney, Richard; Oglevie, Ron; Olszewski, Mitch
Integrated Power and Attitude Control System (IPACS) studies performed over a decade ago established the feasibility of storing electrical energy in flywheels and utilizing the resulting angular momentum for spacecraft attitude control. Such a system has been shown to have numerous attractive features relative to more contemporary technology, and is appropriate to many applications (including high-performance slewing actuators). Technology advances over the last two decades in composite rotors, motor/generator/electronics, and magnetic bearings are found to support the use of IPACS for increasingly sophisticated applications. It is concluded that the concept offers potential performance advantages as well as savings in mass and life-cycle cost. Viewgraphs and discussion on IPACS are included.
Hall, Robert A.; Hough, Steven; Orphee, Carolina; Clements, Keith
NASA is providing preliminary design and requirements for the Space Launch System Exploration Upper Stage (EUS). The EUS will provide upper stage capability for vehicle ascent as well as on-orbit control capability. Requirements include performance of on-orbit burn to provide Orion vehicle with escape velocity. On-orbit attitude control is accommodated by a on-off Reaction Control System (RCS). Paper provides overview of approaches for design and stability of an attitude control system using a RCS.
Bak, Thomas; Wisniewski, Rafal; Blanke, M.
The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system.......The Ørsted Satellite mission imposes comparatively high requirements on autonomy of the attitude control system....
Placanica, Samuel J.; Flatley, Thomas W.
The Cosmic Background Explorer (COBE) spacecraft will be launched by the Shuttle from Vandenberg AFB into a 300 km altitude, 99 deg inclination, 6 a.m. or 6 p.m. ascending node orbit. After release from the Remote Manipulator System (RMS) arm, an on-board monopropellant hydrazine propulsion system will raise the orbit altitude to 900 km. The spacecraft continuously spins during transfer orbit operations with the spin axis nominally horizontal and in or near the orbit plane. The blowdown propulsion system consists of twelve 5 lb thrusters (3 'spin', 3 'despin', and 6 'axial') with the latter providing initially 30 lb of force parallel to the spin axis for orbit raising. The spin/despin jets provide a constant roll rate during the transfer orbit phase of the mission and the axials control pitch and yaw. The axial thrusters are pulsed on for attitude control during coast periods and are normally on- and off-modulated for control during orbit raising. Attitude sensors employed in the control loops include an array of two-axis digital sun sensors and three planar earth scanners for position measurements, as well as six gyroscopes for rate information. System redundancy is achieved by means of unique three-axes-in-a-plane geometry. This triaxial concept results in a fail-safe operational system with no performance degradation for many different component failure modes.
Luiz Carlos Gadelha de Souza
Full Text Available The design of the satellite attitude control system (ACS becomes more complex when the satellite structure has different type of components like, flexible solar panels, antennas, mechanical manipulators, and tanks with fuel. A crucial interaction can occur between the fuel slosh motion and the satellite rigid motion during translational and/or rotational manoeuvre since these interactions can change the satellite centre of mass position damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. As a result, the design of the satellite controller needs to explore the limits between the conflicting requirements of performance and robustness. This paper investigates the effects of the interaction between the liquid motion (slosh and the satellite dynamics in order to predict what the damage to the controller performance and robustness is. The fuel slosh dynamics is modelled by a pendulum which parameters are identified using the Kalman filter technique. This information is used to design the satellite controller by the linear quadratic regulator (LQR and linear quadratic Gaussian (LQG methods to perform a planar manoeuvre assuming thrusters are actuators.
Yu, Xiang; Liu, Kun
A novel roll-channel attitude control scheme using a combination of single-gimbal control moment gyros and a reaction control system is proposed, providing sufficient control torque during the whole reentry process...
Shrewsberry, D. J.; Budney, T. J.; Riley, D. C.; Schuler, B. C.
The STRAP IV attitude control system was designed, tested, and successfully launched to provide stable high accuracy pointing at nontrackable X-ray sources. On its initial flight (May 19, 1972), the STRAP IV control system updated its high accuracy, rate integrating gyros on two successive stellar targets and then maneuvered the rocket body to point the experimental payload at two separate X-ray sources and an X-ray-free background location. The third axis, which remained under the control of a coarse free gyro, was updated by a technique of successive star-target coordinate transformation to ensure the correct fine-axis azimuth alignment for the high accuracy inertial maneuvers. Pointing accuracies of 4 arc min with limit cycle stability of less than 20 arc sec peak to peak were obtained on all targets.
National Aeronautics and Space Administration — We propose to develop and test key technologies needed for an integrated, high thrust colloid thruster system with no moving parts, for spacecraft attitude control...
Budney, T. J.; Collinson, T. W.; Stone, R. W.
The STRAP V system was developed to provide higher accuracy and lower limit cycle fine pointing (+ or - 7 arcseconds) in all three axes at targets which cannot be tracked by startrackers or solar trackers. The system provides an increase in pointing performance over that obtainable with the STRAP IV (1) Attitude Control System (ACS). The STRAP IV concept of third axis updates is utilized to reduce pointing errors, using the flight-proven STRAP III (2) system as a first stage. Flight aspect photographs and telemetry records show that the STRAP V objectives have been met. The STRAP IV major error contributors have been significantly reduced and the tracking flexibility has been increased with only minor error contributions. Attention is given to the basic STRAP III control modes, major STRAP IV system error sources, tuned restrained inertial gyros (TRIGs), the programmable sequence timer, the STRAP V control box, third axis update, system gyro alignments, and STRAP V operational capabilities.
Wenya Zhou; Haixu Wang; Zhengwei Ruan; Zhigang Wu; Enmei Wang
In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on ...
Full Text Available Attitude dynamic model of unmanned aerial vehicles (UAVs is multi-input multioutput (MIMO, strong coupling, and nonlinear. Model uncertainties and external gust disturbances should be considered during designing the attitude control system for UAVs. In this paper, feedback linearization and model reference adaptive control (MRAC are integrated to design the attitude control system for a fixed wing UAV. First of all, the complicated attitude dynamic model is decoupled into three single-input single-output (SISO channels by input-output feedback linearization. Secondly, the reference models are determined, respectively, according to the performance indexes of each channel. Subsequently, the adaptive control law is obtained using MRAC theory. In order to demonstrate the performance of attitude control system, the adaptive control law and the proportional-integral-derivative (PID control law are, respectively, used in the coupling nonlinear simulation model. Simulation results indicate that the system performance indexes including maximum overshoot, settling time (2% error range, and rise time obtained by MRAC are better than those by PID. Moreover, MRAC system has stronger robustness with respect to the model uncertainties and gust disturbance.
Full Text Available The problem of spacecraft attitude control is solved using an adaptive neuro-fuzzy inference system (ANFIS. An ANFIS produces a control signal for one of the three axes of a spacecraft’s body frame, so in total three ANFISs are constructed for 3-axis attitude control. The fuzzy inference system of the ANFIS is initialized using a subtractive clustering method. The ANFIS is trained by a hybrid learning algorithm using the data obtained from attitude control simulations using state-dependent Riccati equation controller. The training data set for each axis is composed of state errors for 3 axes (roll, pitch, and yaw and a control signal for one of the 3 axes. The stability region of the ANFIS controller is estimated numerically based on Lyapunov stability theory using a numerical method to calculate Jacobian matrix. To measure the performance of the ANFIS controller, root mean square error and correlation factor are used as performance indicators. The performance is tested on two ANFIS controllers trained in different conditions. The test results show that the performance indicators are proper in the sense that the ANFIS controller with the larger stability region provides better performance according to the performance indicators.
Bakri, F. A.; Mashor, M. Y.; Sharun, S. M.; Bibi Sarpinah, S. N.; Abu Bakar, Z.
This study proposes an adaptive fuzzy controller for attitude control system (ACS) of Innovative Satellite (InnoSAT) based on direct action type structure. In order to study new methods used in satellite attitude control, this paper presents three structures of controllers: Fuzzy PI, Fuzzy PD and conventional Fuzzy PID. The objective of this work is to compare the time response and tracking performance among the three different structures of controllers. The parameters of controller were tuned on-line by adjustment mechanism, which was an approach similar to a PID error that could minimize errors between actual and model reference output. This paper also presents a Model References Adaptive Control (MRAC) as a control scheme to control time varying systems where the performance specifications were given in terms of the reference model. All the controllers were tested using InnoSAT system under some operating conditions such as disturbance, varying gain, measurement noise and time delay. In conclusion, among all considered DA-type structures, AFPID controller was observed as the best structure since it outperformed other controllers in most conditions.
Full Text Available In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.
Chak, Yew-Chung; Varatharajoo, Renuganth; Razoumny, Yury
This paper investigates the combined attitude and sun-tracking control problem in the presence of external disturbances and internal disturbances, caused by flexible appendages. A new method based on Pythagorean trigonometric identity is proposed to drive the solar arrays. Using the control input and attitude output, a disturbance observer is developed to estimate the lumped disturbances consisting of the external and internal disturbances, and then compensated by the disturbance observer-based controller via a feed-forward control. The stability analysis demonstrates that the desired attitude trajectories are followed even in the presence of external disturbance and internal flexible modes. The main features of the proposed control scheme are that it can be designed separately and incorporated into the baseline controller to form the observer-based control system, and the combined attitude and sun-tracking control is achieved without the conventional attitude actuators. The attitude and sun-tracking performance using the proposed strategy is evaluated and validated through numerical simulations. The proposed control solution can serve as a fail-safe measure in case of failure of the conventional attitude actuator, which triggered by automatic reconfiguration of the attitude control components.
Full Text Available We present a satellite attitude control system design using low-cost hardware and software for a 1U CubeSat. The attitude control system architecture is a crucial subsystem for any satellite mission since precise pointing is often required to meet mission objectives. The accuracy and precision requirements are even more challenging for small satellites where limited volume, mass, and power are available for the attitude control system hardware. In this proposed embedded attitude control system design for a 1U CubeSat, pointing is obtained through a two-stage approach involving coarse and fine control modes. Fine control is achieved through the use of three reaction wheels or three magnetorquers and one reaction wheel along the pitch axis. Significant design work has been conducted to realize the proposed architecture. In this paper, we present an overview of the embedded attitude control system design; the verification results from numerical simulation studies to demonstrate the performance of a CubeSat-class nanosatellite; and a series of air-bearing verification tests on nanosatellite attitude control system hardware that compares the performance of the proposed nonlinear controller with a proportional-integral-derivative controller.
Blevins, Bruce Allyn; Sank, Victor J.
A member of the constellation of TDR satellites (TDRS) has experienced a failure of its prime earth sensor. Failure of the remaining earth sensor could result in the inability of the satellite to control its attitude and provide user services. Loss of the satellite would be a serious event. The multiple access (MA) antenna array on the TDRS has been proposed for use as a backup sensor for the attitude control system. This paper describes our analysis of the performance of the MA array as an interferometer used for accurate attitude determination. A least squares fit of a plane to the MA phase information appears to represent the TDRS body roll and pitch within about 0.1 deg. This is sufficient for SGL pointing and MA and SSA user services. Analytic improvements that include ionospheric correction may yield sufficient accuracy for KSA user services.
National Aeronautics and Space Administration — The development of Plug-and-play Compatibility for CubeSat Attitude Determination and Control Systems (ADACS) is proposed. Existing Maryland Aerospace (MAI) ADACS...
control using a CMG array is prone to geometric singularities. Singularities are commonly avoided by limiting a vehicle’s performance via limitation of the...ball bearings, tolerancing and fitting, materials, or balancing. For help in these areas, where I had only general knowledge, we looked to experts
Full Text Available A quadrotor helicopter with uncertain actuator faults, such as loss of effectiveness and lock-in-place, is studied in this paper. An adaptive fuzzy sliding mode controller based on direct self-repairing control is designed for such nonlinear system to track the desired output signal, when any actuator of this quadrotor helicopter is loss of effectiveness or stuck at some place. Moreover, using the Lyapunov stability theory, the stability of the whole system and the convergence of the tracking error can be guaranteed. Finally, the availability of the proposed method is verified by simulation on 3-DOF hover to ensure that the system performance under faulty conditions can be quickly recovered to its normal level. And this proposed method is also proved to be better than that of LQR through simulation.
Full Text Available A semi-physical simulation platform for attitude determination and control system is proposed to verify the attitude estimator and controller on ground. A simulation target, a host PC, many attitude sensors, and actuators compose the simulation platform. The simulation target is composed of a central processing unit board with VxWorks operating system and many input/output boards connected via Compact Peripheral Component Interconnect bus. The executable programs in target are automatically generated from the simulation models in Simulink based on Real-Time Workshop of MATLAB. A three-axes gyroscope, a three-axes magnetometer, a sun sensor, a star tracer, three flywheels, and a Global Positioning System receiver are connected to the simulation target, which formulates the attitude control cycle of a satellite. The simulation models of the attitude determination and control system are described in detail. Finally, the semi-physical simulation platform is used to demonstrate the availability and rationality of the control scheme of a micro-satellite. Comparing the results between the numerical simulation in Simulink and the semi-physical simulation, the semi-physical simulation platform is available and the control scheme successfully achieves three-axes stabilization.
Yu, Dong Hyeon; Chong, Kil To [Chon-bok National University, Jeonju (Korea, Republic of); Park, Jong Ho [Seonam University, Namwon (Korea, Republic of); Ryu, Ji Hyoung [ETRI, Daejeon (Korea, Republic of)
This paper presents the results of study for improving the reliability of quadrotor attitude control by applying a multi-sensor along with a data fusion algorithm. First, a mathematical model of the quadrotor dynamics was developed. Then, using the quadrotor mathematical model, simulations were performed using the improved reliability multi-sensor data as the inputs. From the simulation results, we designed a Gimbal-equipped quadrotor system. With the quadrotor in a hover state, we performed experiments according to the angle change of the user's specifications . We then calculated the attitude control data from the actual experimental data. Furthermore, with additional simulations, we verified the performance of the designed quadrotor attitude control system with multiple sensors.
Funase, Ryu; Shirasawa, Yoji; Mimasu, Yuya; Mori, Osamu; Tsuda, Yuichi; Saiki, Takanao; Kawaguchi, Jun'ichiro
This paper introduces a new attitude control system for a solar sail, which leverages solar radiation pressure. This novel system achieves completely fuel-free and oscillation-free attitude control of a flexible spinning solar sail. This system consists of thin-film-type devices that electrically control their optical parameters such as reflectivity to generate an imbalance in the solar radiation pressure applied to the edge of the sail. By using these devices, minute and continuous control torque can be applied to the sail to realize very stable and fuel-free attitude control of the large and flexible membrane. The control system was implemented as an optional attitude control system for small solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). In-orbit attitude control experiments were conducted, and the performance of the controller was successfully verified in comparison with the ground-based analytical performance estimation.
Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung
A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.
Peters, W. H.
Development of the Apollo thrust vector control digital autopilot (TVC DAP) was summarized. This is the control system that provided pitch and yaw attitude control during velocity change maneuvers using the main rocket engine on the Apollo service module. A list of ten primary functional requirements for this control system are presented, each being subordinate to a more general requirement appearing earlier on the list. Development process functions were then identified and the essential information flow paths were explored. This provided some visibility into the particular NASA/contractor interface, as well as relationships between the many individual activities.
Xu, Yun-Jun; Fitz-Coy, Norman; Mason, Paul
Formation flying systems can range from global constellations offering extended service coverage to clusters of highly coordinated vehicles that perform distributed sensing. Recently, the use of groups of micro-satellites in the areas of near Earth explorations, deep space explorations, and military applications has received considerable attention by researchers and practitioners. To date, most proposed control strategies are based on linear models (e.g., Hill-Clohessy-Wiltshire equations) or nonlinear models that are restricted to circular reference orbits. Also, all models in the literature are uncoupled between relative position and relative attitude. In this paper, a generalized dynamic model is proposed. The reference orbit is not restricted to the circular case. In this formulation, the leader or follower satellite can be in either a circular or an elliptic orbit. In addition to maintaining a specified relative position, the satellites are also required to maintain specified relative attitudes. Thus the model presented couples vehicle attitude and orbit requirements. Orbit perturbations are also included. In particular, the J(sub 2) effects are accounted in the model. Finally, a sliding mode controller is developed and used to control the relative attitude of the formation and the simulation results are presented.
Simulation is an important tool in the analysis and design of spacecraft attitude control systems. The speaker will discuss the simulation tool, called simply 42, that he has developed over the years to support his own work as an engineer in the Attitude Control Systems Engineering Branch at NASA Goddard Space Flight Center. 42 was intended from the outset to be high-fidelity and powerful, but also fast and easy to use. 42 is publicly available as open source since 2014. The speaker will describe some of 42's models and features, and discuss its applicability to studies ranging from early concept studies through the design cycle, integration, and operations. He will outline 42's architecture and share some thoughts on simulation development as a long-term project.
Greeb, M. E.; True, G. A.
The development of a balloon-borne attitude control system for infrared astronomy studies is discussed. The Balloon Infrared Astronomy Platform (BIRAP) is the result of the development effort. The BIRAP uses electronic gimballing for the offset pointing which eliminates a set of mechanical gimbals. Guide stars with visual magnitudes as low as plus 6 are used for fine tracking assuring that all areas of the sky can be covered. The BIRAP control concept uses a closed loop system in the airborne equipment with automatic update through a command link that can be operated either manually or automatically by a ground based computer.
A system for automatic acquisition of underwater platform attitude data has been designed, developed and tested in the laboratory. This is a micro controller based system interfacing dual axis inclinometer, high-resolution digital compass...
Full Text Available This paper proposes a finite-time robust flight controller, targeting for a reentry vehicle with blended aerodynamic surfaces and a reaction control system (RCS. Firstly, a novel finite-time attitude controller is pointed out with the introduction of a nonsingular finite-time sliding mode manifold. The attitude tracking errors are mathematically proved to converge to zero within finite time which can be estimated. In order to improve the performance, a second-order finite-time sliding mode controller is further developed to effectively alleviate chattering without any deterioration of robustness and accuracy. Moreover, an optimization control allocation algorithm, using linear programming and a pulse-width pulse-frequency (PWPF modulator, is designed to allocate torque commands for all the aerodynamic surface deflections and on–off switching-states of RCS thrusters. Simulations are provided for the reentry vehicle considering uncertain parameters and external disturbances for practical purposes, and the results demonstrate the effectiveness and robustness of the attitude control system.
Besonis, A.; Dougherty, H.; Levinthal, J.; Meadows, P.
A technique, utilized on the Space Telescope Program, and used for testing satellite attitude pointing and control systems during the engineering and development phases is presented. The technique verifies the hardware models used in design phase computer simulations, verifies the interface between the flight hardware and flight software, and uncovers hardware/software switching or mode logic problems. The testing is accomplished in two phases: a dynamic hardware simulator phase using hardware electronic simulators and an electronic vehicle motion simulator; and a second real hardware phase utilizing engineering model gyros and reaction wheels on an airbearing table. Both phases use an engineering model of the flight computer, flight algorithms and software, and a breadboard data management and computer hardware interface for timing simulations. The purpose of each test and the test phases are described, and examples of closed loop test results for both attitude hold and maneuvering models are given.
Reijneveld, J.; Choukroun, D.
This work is concerned with the development of the attitude control algorithms that will be implemented on board of the Delfi-n3xt nanosatellite, which is to be launched in 2013. One of the mission objectives is to demonstrate Sun pointing and three axis stabilization. The attitude control modes and
Starin, Scott R.; Vess, Melissa F.; Kenney, Thomas M.; Maldonado, Manuel D.; Morgenstern, Wendy M.
The Solar Dynamics Observatory is an Explorer-class mission that will launch in early 2009. The spacecraft will operate in a geosynchronous orbit, sending data 24 hours a day to a devoted ground station in White Sands, New Mexico. It will carry a suite of instruments designed to observe the Sun in multiple wavelengths at unprecedented resolution. The Atmospheric Imaging Assembly includes four telescopes with focal plane CCDs that can image the full solar disk in four different visible wavelengths. The Extreme-ultraviolet Variability Experiment will collect time-correlated data on the activity of the Sun's corona. The Helioseismic and Magnetic Imager will enable study of pressure waves moving through the body of the Sun. The attitude control system on Solar Dynamics Observatory is responsible for four main phases of activity. The physical safety of the spacecraft after separation must be guaranteed. Fine attitude determination and control must be sufficient for instrument calibration maneuvers. The mission science mode requires 2-arcsecond control according to error signals provided by guide telescopes on the Atmospheric Imaging Assembly, one of the three instruments to be carried. Lastly, accurate execution of linear and angular momentum changes to the spacecraft must be provided for momentum management and orbit maintenance. In thsp aper, single-fault tolerant fault detection and correction of the Solar Dynamics Observatory attitude control system is described. The attitude control hardware suite for the mission is catalogued, with special attention to redundancy at the hardware level. Four reaction wheels are used where any three are satisfactory. Four pairs of redundant thrusters are employed for orbit change maneuvers and momentum management. Three two-axis gyroscopes provide full redundancy for rate sensing. A digital Sun sensor and two autonomous star trackers provide two-out-of-three redundancy for fine attitude determination. The use of software to maximize
Schreiner, John N.
This thesis proposes a method of performing fault detection and isolation in spacecraft attitude determination and control systems. The proposed method works by deploying a trained neural network to analyze a set of residuals that are defined such that they encompass the attitude control, guidance, and attitude determination subsystems. Eight neural networks were trained using either the resilient backpropagation, Levenberg-Marquardt, or Levenberg-Marquardt with Bayesian regularization training algorithms. The results of each of the neural networks were analyzed to determine the accuracy of the networks with respect to isolating the faulty component or faulty subsystem within the ADCS. The performance of the proposed neural network-based fault detection and isolation method was compared and contrasted with other ADCS FDI methods. The results obtained via simulation showed that the best neural networks employing this method successfully detected the presence of a fault 79% of the time. The faulty subsystem was successfully isolated 75% of the time and the faulty components within the faulty subsystem were isolated 37% of the time.
Shen, H; Xu, Y; Dickinson, B T
Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands.
Orphee, Juan; Diedrich, Ben; Stiltner, Brandon; Becker, Chris; Heaton, Andrew
An Attitude Control System (ACS) has been developed for the NASA Near Earth Asteroid (NEA) Scout mission. The NEA Scout spacecraft is a 6U cubesat with an eighty-six square meter solar sail for primary propulsion that will launch as a secondary payload on the Space Launch System (SLS) Exploration Mission 1 (EM-1) and rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Active Mass Translator (AMT) system. The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The Momentum Management System (MMS) keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS. The AMT is used to adjust the sign and magnitude of the solar torque to manage pitch and yaw momentum. The RCS is used for initial de-tumble, performing a Trajectory Correction Maneuver (TCM), and performing momentum management about the roll axis. The NEA Scout ACS is able to meet all mission requirements including attitude hold, slews, pointing for optical navigation and pointing for science with margin and including flexible body effects. Here we discuss the challenges and solutions of meeting NEA Scout mission requirements for the ACS design, and present a novel implementation of managing the spacecraft Center of Mass (CM) to trim the solar sail disturbance torque. The ACS we have developed has an applicability to a range of potential missions and does so in a much smaller volume than is traditional for deep space missions beyond Earth.
Peacock, W. M.
The ITOS with an improved attitude control system is described. A Hall generator brushless dc torque motor will replace the brush dc torque motor on ITOS-I and ITOS-A (NOAA-1). The four attitude horizon sensors will be replaced with two CO2 sensors for better horizon definition. An earth horizon splitting technique will be used to keep the earth facing side of the satellite toward earth even if the desired circular orbit is not achieved. The external appearance of the pitch control subsystem differs from TIROS-M (ITOS-1) and ITOS-A (NOAA-1) in that two instead of one pitch control electronics (PCE) boxes are used. Two instead of four horizon sensors will be used and one instead of two mirrors will be used for sensor scanning. The brushless motor will eliminate the requirement for brushes, strain gages and the telemetry for the brush wear. A single rotating flywheel, supported by a single bearing provides the gyroscopic stability and the required momentum interchange to keep one side of the satellite facing the earth. Magnetic torquing against the earth's magnetic field eliminates the requirement for expendable propellants which would limit satellite life in orbit.
Wisniewski, Rafal; Markley, F.L.
because control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis stabilization of a low earth orbit satellite. The problem of controlling the spacecraft attitude using only magnetic......Magnetic torquing is attractive as means of control for small satellites. The actuation principle is to use the interaction between the earth's magnetic field and a magnetic field generated by a coil set in the satellite. This control principle is inherently time-varying, and difficult to use...
Reid, Daniel F.; Studer, Phillip A.
The goals were to establish the Attitude Control System (ACS) requirements, constraints, technology assessment, technology shortfalls, expected in the year 2000. These were based upon all missions, military and civil, for LEO and GEO. The critical ACS technology issues were identified and ACS programs developed to address these critical issues.
Lee, Byoung-Sun; Kim, Jae-Hoon; Eun, Jong-Won; Kim, Jae-Moung
A ground-based backup attitude control software for the KOREASAT spacecraft was developed. The software is called the Ground Loop Control (GLC). GLC is activated by satellite operator when both Attitude Processor Electronics (APE) of the spacecraft are failed. GLC extracts pitch and roll angles from the normal spacecraft telemetry, and then generates momentum wheel and magnetic torquer commands simultaneously. This paper presents the design of the GLC software and the test of the GLC linked with KOREASAT Dynamic Satellite Simulator (DSS).
Wie, Bong; Roithmayr, Carlos M.
The major objective of this study is to develop an integrated orbit, attitude, and structural control systems architecture for very large Space Solar Power Satellites (SSPS) in geosynchronous orbit. This study focuses on the 1.2-GW Abacus SSPS concept characterized by a 3.2 x 3.2 km solar-array platform, a 500-m diameter microwave beam transmitting antenna, and a 500 x 700 m earth-tracking reflector. For this baseline Abacus SSPS configuration, we derive and analyze a complete set of mathematical models, including external disturbances such as solar radiation pressure, microwave radiation, gravity-gradient torque, and other orbit perturbation effects. The proposed control systems architecture utilizes a minimum of 500 1-N electric thrusters to counter, simultaneously, the cyclic pitch gravity-gradient torque, the secular roll torque caused by an offset of the center-of-mass and center-of-pressure, the cyclic roll/yaw microwave radiation torque, and the solar radiation pressure force whose average value is about 60 N.
Woods-Vedeler, Jessica (Technical Monitor); Moore, Chris (Technical Monitor); Wie, Bong; Roithmayr, Carlos
The major objective of this study is to develop an integrated orbit, attitude, and structural control system architecture for very large Space Solar Power Satellites (SSPS) in geosynchronous orbit. This study focuses on the 1.2-GW Abacus SSPS concept characterized by a 3.2 x 3.2 km solar-array platform, a 500-m diameter microwave beam transmitting antenna, and a 500 700 m earth-tracking reflector. For this baseline Abacus SSPS configuration, we derive and analyze a complete set of mathematical models, including external disturbances such as solar radiation pressure, microwave radiation, gravity-gradient torque, and other orbit perturbation effects. The proposed control system architecture utilizes a minimum of 500 1-N electric thrusters to counter, simultaneously, the cyclic pitch gravity-gradient torque, the secular roll torque caused by an o.set of the center-of-mass and center-of-pressure, the cyclic roll/yaw microwave radiation torque, and the solar radiation pressure force whose average value is about 60 N.
DISTRIBUTION A. Approved for public release: distribution unlimited. Integration of a Motion Capture System into a Spacecraft Simulator for Real-Time...integrated with a Phase- Space Impulse X2 motion capture system. This system calculates the testbed’s inertial attitude, which can be used to simulate various...generate measurements via another source. To that end, a PhaseSpace Impulse X2 motion capture system has been integrated with the ACSPG and a wireless
Jansen, Ralph H.
On September 14, 2004, NASA Glenn Research Center's Flywheel Development Team experimentally demonstrated a full-power, high-speed, two-flywheel system, simultaneously regulating a power bus and providing a commanded output torque. Operation- and power-mode transitions were demonstrated up to 2000 W in charge and 1100 W in discharge, while the output torque was simultaneously regulated between plus or minus 0.8 N-m. The G2 and D1 flywheels--magnetically levitated carbon-fiber wheels with permanent magnet motors--were used for the experiment. The units were mounted on an air bearing table in Glenn's High Energy Flywheel Facility. The operational speed range for these tests was between 20,000 and 60,000 rpm. The bus voltage was regulated at 125 V during charge and discharge, and charge-discharge and discharge-charge transitions were demonstrated by changing the amount of power that the power supply provided between 300 and 0 W. In a satellite system, this would be the equivalent of changing the amount of energy that the solar array provides to the spacecraft. In addition to regulating the bus voltage, we simultaneously controlled the net torque produced by the two flywheel modules. Both modules were mounted on an air table that was restrained by a load cell. The load cell measured the force on the table, and the torque produced by the two flywheels on the table could be calculated from that measurement. This method was used to measure the torque produced by the modules, yielding net torques from -0.8 to 0.8 N-m. This was the first Glenn demonstration of the Integrated Power and Attitude Control System (IPACS) at high power levels and speeds.
Viswanathan, Sasi Prabhakaran
how they lead to CMG singularities, are described. General ideas on control of the angular momentum of the spacecraft using changes in the momentum variables of a finite number of ASCMGs, are provided. Control schemes for agile and precise attitude maneuvers using ASCMG cluster in the absence of external torques and when the total angular momentum of the spacecraft is zero, is presented for both constant speed and variable speed modes. A Geometric Variational Integrator (GVI) that preserves the geometry of the state space and the conserved norm of the total angular momentum is constructed for numerical simulation and microcontroller implementation of the control scheme. The GVI is obtained by discretizing the Lagrangian of the rnultibody systems, in which the rigid body attitude is globally represented on the Lie group of rigid body rotations. Hardware and software architecture of a novel spacecraft Attitude Determination and Control System (ADCS) based on commercial smartphones and a bare minimum hardware prototype of an ASCMG using low cost COTS components is also described. A lightweight, dynamics model-free Variational Attitude Estimator (VAE) suitable for smartphone implementation is employed for attitude determination and the attitude control is performed by ASCMG actuators. The VAE scheme presented here is implemented and validated onboard an Unmanned Aerial Vehicle (UAV) platform and the real time performance is analyzed. On-board sensing, data acquisition, data uplink/downlink, state estimation and real-time feedback control objectives can be performed using this novel spacecraft ADCS. The mechatronics realization of the attitude determination through variational attitude estimation scheme and control implementation using ASCMG actuators are presented here. Experimental results of the attitude estimation (filtering) scheme using smartphone sensors as an Inertial Measurement Unit (IMU) on the Hardware In the Loop (HIL) simulator testbed are given. These
National Aeronautics and Space Administration — Busek proposes to develop and deliver a complete engineering model colloid thruster system, capable of thrust levels and lifetimes required for spacecraft...
George Cristian Calugaru
Full Text Available This paper proposes a method for an efficient control of the aircraft landing and attitude through Dynamic Matrix Control. The idea of MPC structures used in aircraft control has been well established during the last few years, but some aspects require further investigation. With this in mind, the paper proposes structures for aircraft landing and aircraft attitude control by using single DMC controllers for landing and respectively one DMC controller for each of the attitude axis (pitch attitude hold, bank angle hold and heading hold. The model used for analysis of the aircraft landing structure is based on the last phase of landing. Also, the model used to illustrate the attitude control is that of a pitch attitude hold system of a N250-100 aircraft. Simulations are performed for a variety of control and prediction horizons, taking into account the possibility of adding a weighting factor for the control actions. Apart from separate studies on step reference variations, for some use cases, a generic reference trajectory is provided as a control purpose of the system. Results show a better performance of the proposed method in terms of control surface transition and protection of the actuators involved and a better time response in stabilizing the aircraft attitude. Overall, the aspects shown ensure an improved aircraft attitude control and landing stabilization.
Davis, R. Benjamin; Fischbach, Sean R.
The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.
MolinaFraticelli, Jose Carlos
This paper details the work done to auto generate C code from a Simulink-Based Attitude Determination Control System (ADCS) to be used in target platforms. NASA Marshall Engineers have developed an ADCS Simulink simulation to be used as a component for the flight software of a satellite. This generated code can be used for carrying out Hardware in the loop testing of components for a satellite in a convenient manner with easily tunable parameters. Due to the nature of the embedded hardware components such as microcontrollers, this simulation code cannot be used directly, as it is, on the target platform and must first be converted into C code; this process is known as auto code generation. In order to generate C code from this simulation; it must be modified to follow specific standards set in place by the auto code generation process. Some of these modifications include changing certain simulation models into their atomic representations which can bring new complications into the simulation. The execution order of these models can change based on these modifications. Great care must be taken in order to maintain a working simulation that can also be used for auto code generation. After modifying the ADCS simulation for the auto code generation process, it is shown that the difference between the output data of the former and that of the latter is between acceptable bounds. Thus, it can be said that the process is a success since all the output requirements are met. Based on these results, it can be argued that this generated C code can be effectively used by any desired platform as long as it follows the specific memory requirements established in the Simulink Model.
Bøgh, S.A.; Izadi-Zamanabadi, Roozbeh; Blanke, M.
The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system.......The increasing operational requirements for onboard autonomy in satellite control systems necessitates structural methods that support the design of a complete and reliable supervisory system....
Souza, Alain Giacobini de; Souza, Luiz Carlos Gadelha de
This paper presents the Attitude Control System (ACS) design for a rigid-flexible satellite with two vibrations mode, using the H infinity method considering the parametric uncertainty over the mass matrix. Usually the mathematic model obtained from the linearization and/or reduction of the rigid flexible model loses information about the flexible dynamical behavior and introduces some uncertainty. As a result, the ACS performance can be degraded when controlling large angle maneuvers. One wa...
Pace, G. D., Jr.; Schmidt, L. F.
Modified wideangle analog cruise sun sensor coupled with changes in optic attitude correction capabilities, eliminate need of acquisition and sun gate sensors, making on-course navigation of spacecraft flying interplanetary missions less risky and costly. Operational characteristics potentially make system applicable to guidance and control of solar energy collection systems.
Sagalyn, R. C.; Smiddy, M.
The feasibility of an attitude control system that uses environmental positive ions and an electrostatic detection system to measure spacecraft pitch and yaw is studied. The secondary objective was to measure the spatial and temporal variations of ambient positively charged particles along the orbital path of the Gemini 10 and 12 spacecrafts. The results proved that the use of a horizon detector in conjunction with pitch and yaw sensors would facilitate complete description of the spacecraft position and attitude. Furthermore, with the addition of a servosystem, the unit could be used as a complete automatic attitude-control system that would be applicable from the lowest satellite altitudes up to at least 10 earth radii. Also, results established that the charge density along the trajectory of the satellite could be determined by transmission of output voltages from the individual electrometers.
Full Text Available “Tian Tuo 1” (TT-1 nano-satellite is the first single-board nano-satellite that was successfully launched in China. The main objective of TT-1 is technology demonstration and scientific measurements. The satellite carries out the significant exploration of single-board architecture feasibility validation, and it is tailored to the low-cost philosophy by adopting numerous commercial-off-the-shelf (COTS components. The satellite is featured with three-axis stabilization control capability. A pitch bias momentum wheel and three magnetic coils are adopted as control actuators. The sun sensors, magnetometers and a three-axis gyro are employed as the measurement sensors. The quaternion estimator (QUEST and unscented Kalman filter (UKF method are adopted for the nano-satellite attitude determination. On-orbit data received by ground station is conducted to analysis the performance of attitude determination and control system (ADCS. The results show that the design of ADCS for TT-1 is suitable, robust and feasible.
Ayodele I., Olanipekun
The nonlinear behavior exhibited by altitude control system processes and also the presence of external constraints on the operating conditions causes hitch in the dynamics of system processes. This research work proposes a fault detection/tolerant prediction in an altitude control system. This is done through the artificial neural network fault detection by deploying the neural network approach. A fault detection and isolation module is developed in the actuator system of the Altitude Control System, thereby achieving the goal of this thesis. This can be done by two basic classification stages: Neural Residual Generator (Neural Observer)- This stage is responsible for generating residual errors that can reflect the real behavior of the entire process as against its normal conditions. Adaptive Neural Classifier - This stage is responsible for managing the isolation task of the fault detected by evaluating the generated residual errors from the neural estimator which gives detailed information about faults detected e.g., fault location and time. These two stages can be implemented by executing the tasks listed below: 1. Study and develop a generic three axis stabilized altitude control model based on the reaction wheels. This is established with three separate PD controllers designed for each reaction wheel of the satellite axis using the Matlab - SIMULINK. 2. Develop a dynamic neural network residual generator based on Dynamic Multilayer Perceptron Network (DMLP) which is then applied to the reaction wheel model designed commonly called the actuator in the altitude control system of a satellite 3. Develop a neural network adaptive classifier based on the Learning Vector Quantization (LVQ) model which is used for the isolation concept. The advantages of the proposed dynamic neural network and neural adaptive classifier approach are showcased.
Engberg, Brian; Spanjers, Greg; Wegner, Peter; Bromaghim, Daron; Fetchko, Pamela; Sellers, Jerry; Lake, Mark; Tupper, Mike; Harvey, Jeff; Evans, Jon
Small satellite missions requiring attitude control can realize significant mass savings by extending the moment arm of a propulsion-based system. Replacing traditional torque rods and reaction wheels with small thrusters on extendable booms can significantly reduce the mass of the ACS. Small satellite buses pose significant integration challenges when incorporating electric micro-thrusters. Generally these satellites have low power capability and small geometries. This impacts attitude deter...
Full Text Available The robust optimal attitude control problem for a flexible spacecraft is considered. Two optimal sliding mode control laws that ensure the exponential convergence of the attitude control system are developed. Integral sliding mode control (ISMC is applied to combine the first-order sliding mode with optimal control and is used to control quaternion-based spacecraft attitude manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state-dependent Riccati equation (SDRE and optimal Lyapunov techniques are employed to solve the infinite-time nonlinear optimal control problem. The second method of Lyapunov is used to guarantee the stability of the attitude control system under the action of the proposed control laws. An example of multiaxial attitude manoeuvres is presented and simulation results are included to verify the usefulness of the developed controllers.
Full Text Available This paper has implemented nonlinear control strategy for the single tilt tri-rotor aerial robot. Based on Newton-Euler’s laws, the linear and nonlinear mathematical models of tri-rotor UAVs are obtained. A numerical analysis using Newton-Raphson method is chosen for finding hovering equilibrium point. Back-stepping nonlinear controller design is based on constructing Lyapunov candidate function for closed-loop system. By imitating the linguistic logic of human thought, fuzzy logic controllers (FLCs are designed based on control rules and membership functions, which are much less rigid than the calculations computers generally perform. Effectiveness of the controllers design scheme is shown through nonlinear simulation model on each channel.
Solar sails are space vehicles that rely on solar radiation pressure in order to generate forces for thrust and attitude control torques. They exhibit characteristics such as large moments of inertia, fragility of various system components, and long mission durations that make attitude control a particularly difficult engineering problem. Thrust vector control (TVC) is a family of sailcraft attitude control techniques that is on a short list of strategies thought to be suitable for the primary attitude control of solar sails. Every sailcraft TVC device functions by manipulating the relative locations of the composite mass center (cm) of the sailcraft and the center of pressure (cp) of at least one of its reflectors. Relative displacement of these two points results in body torques that can be used to steer the sailcraft. This dissertation presents a strategy for the large-angle reorientation of a sailcraft using TVC. Two forms of TVC, namely the panel and ballast mass translation methods are well represented in the literature, while rigorous studies regarding a third form, gimballed mass rotation, are conspicuously absent. The gimballed mass method is physically realized by placing a ballast mass, commonly the sailcraft's scientific payload, at the tip of a gimballed boom that has its base fixed at some point on the sailcraft. A TVC algorithm will then strategically manipulate the payload boom's gimbal angles, thereby changing the projection of the sailcraft cm in the plane of the sail. This research demonstrates effective three-axis attitude control of a model sailcraft using numerical simulation of its nonlinear equations of motion. The particular TVC algorithm developed herein involves two phases---the first phase selects appropriate gimbal rates with the objective that the sailcraft be placed in the neighborhood of its target orientation. It was discovered, however that concomitantly minimizing attitude error as well as residual body rate was not possible using
Torczynski, D.M.; Amini, R.; Massioni, P.
This paper presents the design of an attitude controller for a magnetically actuated nanosatellite. The goal of this attitude control system is to be able to dump excess kinetic rotational energy as well as to point to a rotating frame with an accuracy of five degrees on each axis. From the options
Including Sensor Bias in Shape from Motion Calibration and Sensor Fusion ”. Multisensor Fusion and Integration for Intelligent Systems, 1996. IEEE/SICE...for attitude determination. Along with the ADCS hardware, the ADCS testbed also includes an Electrical Power System (EPS) and Command and Data ...eter sensor data to estimate a current quaternion. A Proportional-Integral-Derivative (PID) controller is used for control of the ADCS testbed while
Xu, Zhong Ling; Zhou, Gui AN
The Inertial Hold Mode (IHM) is one mode of the attitude control system of the X-ray Timing Explorer spacecraft that is disturbed by both parametric uncertainties and external torque disturbance. The IHM model is modified into a typical H-infinity mixed-sensitivity problem through choosing suitable weighting functions W(sub 1)(s) and W(sub 3)(s). The controller is designed by the H-infinity optimization technique with the transformation of shifting the imaginary axis. It can stabilize the plant with uncertainties from the natural frequencies of the flexible body. The gain margin and phase margin of the system are 24.03 db and 55.04 deg, respectively. The step response attenuates to zero within 150 seconds. These show that the controller satisfies the specified requirements. Since the order of the controller appears high, it is reduced to fourth order one. The results show that the stability and the performance of the system with the reduced controller are retained perfectly.
Peacock, W. M.
The National Aeronautics and Space Administration (NASA), launched ITOS-D with an improved attitude control system. A Hall generator brushless dc torque motor replaced the brush dc torque motor on Tiros-M and ITOS-A. Two CO2 attitude horizon sensors and one mirror replaced the four wideband horizon sensors and two mirrors on ITOS-1 and NOAA-1. Redundant pitch-control electronic boxes containing additional electronic circuitry for earth-splitting and brushless motor electronics were used. A method of generating a spacecraft earth-facing side reference for comparison to the time occurrence of the earth-splitting pulse was used to automatically correct pitch-attitude error. A single rotating flywheel, supported by a single bearing, provided gyroscopic stability and the required momentum interchange to keep one side of the satellite facing the earth. Magnetic torquing against the earth's magnetic field eliminated the requirement for expendable propellants which would limit satellite life in orbit.
Ekrami, Yasamin; Cook, Joseph S.
In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.
Westfall, Alexander J.
This paper describes the design process of developing a spin-axis control system for a 3U CubeSat, a relatively small satellite. Design requires the CubeSat to de-spin after deployment and direct its antenna to track Earth nadir position. The one degree of freedom controller is developed for the TechEdSat, which is a CubeSat with a payload that allows for the assumption that rotation pitch and yaw rates are sufficiently close to zero. Satellite torqueing disturbances are modeled with reaction wheel noise for a more complete system analysis. Sensor noise is unmodeled. Frequency domain and time domain analyses are presented; the entire system bandwidth operates at 0.08 hertz with 43.2 decibels of gain and 67.7° of phase margin. During nominal operations, pointing accuracy with perfect state knowledge assumption maintains position with steady state error of 13.7 arc seconds and oscillates by 16.7 arc seconds at a rate of 0.7 mHertz. Artificial wheel noise is injected into the model causing the pointing accuracy to drop to +/- 15 arc seconds. Environmental disturbances are modeled extensively; the magnetic field torque is the worst disturbance, at 4.2e-7 Newton-meters. A 0.2 Amp˙m2 magnetorquer dumps the excess momentum every 7.75 hours and require 1.5 hours to complete. In the deployment simulation, a 1 rotation per minute spin is arrested with no angular offset in 60 seconds. Future plans include utilizing the model to build and fly a prototype reaction wheel on a future TechEdSat mission to verify modeled expectations.
Sørensen, Bjarne Taulo
production systems was modelled. The analysis was based on data from a cross-cultural survey involving 1931 participants from Belgium, Denmark, Germany and Poland. The survey questionnaire contained measures of personal value orientations and attitudes towards environment and nature, industrial food...
Keum, Jung-Hoon; Ra, Sung-Woong
Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.
Robins, A. W.; Beissner, F. L., Jr.; Domack, C. S.; Swanson, E. E.
A performance study was made of a vertical attitude takeoff and landing (VATOL), supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system. Those characteristics considered were aerodynamics, weight, balance, and performance. Preliminary results indicate that high levels of supersonic aerodynamic performance can be achieved. Further, with the assumption of an advanced (1985 technology readiness) low bypass ratio turbofan engine and advanced structures, excellent mission performance capability is indicated.
for each axis is 3 The modular nature of the flight computer control software (as discussed in...performed using the Setup Wizard tool in EPOS Studio; see Appendix A for a complete listing of the Setup Wizard settings used for the gimbal and momentum...1.00 rad/sec as compared with an approximately 15 percent reduction at ± 0.25 rad/sec). While the slight sinusoidal nature of the updated momentum
Ham, N. D.
A theoretical study is presented on the application of the Individual-Blade-Control concept to helicopter attitude stabilization. The design of a system controlling blade flapping dynamics, and related testing of the system on a model rotor in the wind tunnel, is described. The control inputs considered are blade pitch changes proportional to blade flapping acceleration, velocity, and displacement. The effect of such a system on helicopter rotor damping-in-pitch, and angle-of-attack stability is then evaluated. It is shown that helicopter attitude stabilization is achieved, with a corresponding improvement in flying qualities.
Full Text Available This paper deals with stabilization and reduced attitude control of a robotic underwater vehicle. The vehicle is assumed to be able to perform a full stable rotations around all axes in underwater space, that is why the standard bottom-heavy structure is not used. The system preferably uses a vectored-thrust arrangement and is built as an overactuated system, which enables to gain a better robustness and guarantees a stable controlled motion even if some thruster suddenly stop working. Because the heading angle cannot be measured, the reduced attitude control strategy is designed and the stability of reduced state of the system is proved using perturbation method.
Bedrossian, Nazareth; Bhatt, Sagar; Alaniz, Abran; McCants, Edward; Nguyen, Louis; Chamitoff, Greg
In this paper, the attitude control issues associated with International Space Station (ISS) loss of automatic thruster control capability are discussed and methods for attitude control recovery are presented. This scenario was experienced recently during Shuttle mission STS-117 and ISS Stage 13A in June 2007 when the Russian GN&C computers, which command the ISS thrusters, failed. Without automatic propulsive attitude control, the ISS would not be able to regain attitude control after the Orbiter undocked. The core issues associated with recovering long-term attitude control using CMGs are described as well as the systems engineering analysis to identify recovery options. It is shown that the recovery method can be separated into a procedure for rate damping to a safe harbor gravity gradient stable orientation and a capability to maneuver the vehicle to the necessary initial conditions for long term attitude hold. A manual control option using Soyuz and Progress vehicle thrusters is investigated for rate damping and maneuvers. The issues with implementing such an option are presented and the key issue of closed-loop stability is addressed. A new non-propulsive alternative to thruster control, Zero Propellant Maneuver (ZPM) attitude control method is introduced and its rate damping and maneuver performance evaluated. It is shown that ZPM can meet the tight attitude and rate error tolerances needed for long term attitude control. A combination of manual thruster rate damping to a safe harbor attitude followed by a ZPM to Stage long term attitude control orientation was selected by the Anomaly Resolution Team as the alternate attitude control method for such a contingency.
Talebi, H A; Khorasani, K; Tafazoli, S
This paper presents a robust fault detection and isolation (FDI) scheme for a general class of nonlinear systems using a neural-network-based observer strategy. Both actuator and sensor faults are considered. The nonlinear system considered is subject to both state and sensor uncertainties and disturbances. Two recurrent neural networks are employed to identify general unknown actuator and sensor faults, respectively. The neural network weights are updated according to a modified backpropagation scheme. Unlike many previous methods developed in the literature, our proposed FDI scheme does not rely on availability of full state measurements. The stability of the overall FDI scheme in presence of unknown sensor and actuator faults as well as plant and sensor noise and uncertainties is shown by using the Lyapunov's direct method. The stability analysis developed requires no restrictive assumptions on the system and/or the FDI algorithm. Magnetorquer-type actuators and magnetometer-type sensors that are commonly employed in the attitude control subsystem (ACS) of low-Earth orbit (LEO) satellites for attitude determination and control are considered in our case studies. The effectiveness and capabilities of our proposed fault diagnosis strategy are demonstrated and validated through extensive simulation studies.
USA Michael V. Nayak § Red Sky Research, Albuquerque, New Mexico , 87108, USA Thorsten Pueschl ¶ dSPACE GmbH, Paderborn, 32102, Germany The work...volume, mass, and power constraints led to the decision of eliminating the reaction wheels in favor of an RCS thruster actuated control system. A trade ...the same distur- bance scenario was presented to the thruster actuated system. The total propellant per orbit needed to reject all exterior
Hingsburger, Dave; Tough, Susan
This article discusses attributes of healthy human service systems and the importance of strong sexual self-advocacy by people with disabilities. It outlines how negative attitudes can have traumatizing effects on people with disabilities and argues that by developing positive attitudes a new era of healthy sexual development can begin. (Contains…
Deng, Mingle; Yue, Baozeng
This paper is focused on attitude tracking control of a spacecraft that is equipped with flexible appendage and partially filled liquid propellant tank. The large amplitude liquid slosh is included by using a moving pulsating ball model that is further improved to estimate the settling location of liquid in microgravity or a zero-g environment. The flexible appendage is modelled as a three-dimensional Bernoulli-Euler beam, and the assumed modal method is employed. A hybrid controller that combines sliding mode control with an adaptive algorithm is designed for spacecraft to perform attitude tracking. The proposed controller has proved to be asymptotically stable. A nonlinear model for the overall coupled system including spacecraft attitude dynamics, liquid slosh, structural vibration and control action is established. Numerical simulation results are presented to show the dynamic behaviors of the coupled system and to verify the effectiveness of the control approach when the spacecraft undergoes the disturbance produced by large amplitude slosh and appendage vibration. Lastly, the designed adaptive algorithm is found to be effective to improve the precision of attitude tracking.
Zhang, Zexiang; Hu, Shengbin
The four - rotor unmanned aerial vehicle (UAV) is the object of study, in this paper. In order to solve the problem of poor robustness and low control precision of the four-rotor unmanned aerial vehicle (UAV) control system, and realized the stability control problem of the four-rotor UAV attitude. First, the dynamic model of the four-rotor unmanned aerial vehicle is established. And on this basis, a fuzzy controller is designed, and used to control the channel. Then, the simulation platform is built by Matlab / Simulink simulation software, and the performance of the designed fuzzy controller is analyzed comprehensively. It is also determined whether the algorithm can control the attitude of the four rotor unmanned aerial vehicle. The simulation results fully verify the accuracy of the model, and proved fuzzy controller has better dynamic performance and robustness under appropriate parameters so that UAVs can fly stable. The algorithm can improve the anti-jamming performance and control accuracy of the system, it has a certain significance for the actual four-rotor aircraft attitude control.
Ermoshkin, Yu; V. Raevsky; Urusov, V.
The paper describes the enhanced application ofhigh-economical electro-jet orbit control thrusters for geostationary satellites; in particular, generation of controlling moments to the benefit of satellite attitude determination and control subsystems in the course of orbit control maneuvers ongoing. The scheme with thrusters fixed on a satellite body is analyzed. Possible orbit control session procedures are proposed on the basis of controlling moments generation. Advantages and disadvantage...
van Bezooijen, Roelof W. H.
The attitude control and navigation systems of future advanced spacecraft will be characterized by a high degree of autonomy, very high accuracy, efficient commandability, and fast fault recovery. These characteristics are incompatible with the constraints of conventional star sensors which mandate a-priori definition of all onboard attitude fixes and work only if attitude uncertainties remain small. With the availability of accurate, anti-blooming capable CCDs, fast microprocessors, high density memory chips, and star pattern recognition algorithms, it is now feasible to fabricate miniature Autonomous Star Trackers (ASTs) capable of (1) determining their attitude rapidly and reliably while having no a-priori attitude knowledge, (2) autonomous attitude updating, and (3) providing their attitude at rates up to typically 40 Hz. In addition to providing the functionality needed for future missions, ASTs can also be exploited to improve the reliability, mass, power, and cost of spacecraft and reduce the cost of operating them. This paper describes star identification schemes used in the past, it discusses a number of star pattern recognition algorithms, and provides the main characteristics of current CCD star trackers. A number of specific functions enabled or enhanced by an AST are described including fast attitude acquisition, rapid fault recovery, attitude safing, gyroless/cheap-gyro attitude control, autonomous target acquisition by astronomy telescopes, autonomous optical navigation, and precision pointing to terrestrial targets. The AST being developed at Lockheed uses a fast, memory-efficient, and highly robust star pattern recognition algorithm based on matching groups of stars. The algorithm, which is also applicable to star scanners, is described along with a realistic simulation program for testing its performance. It is shown that an AST with an 11.3 degree FOV diameter, a database of 4100 guide stars, a 25 MHz MC68030 class microprocessor, and 800 Kbytes
Full Text Available The path tracking control algorithm is one of the key problems in the control system design of autonomous vehicle. In this paper, we have conducted dynamic modeling for autonomous vehicle, the relationship between course deviation and yaw rate and centroid deflection angle. From the angle of the dynamics and geometrical, this paper have described the path tracking problem, analyzed the emergence of the eight autonomous vehicles pose binding - position and attitude alternate control methods to identify the relationship between posture and the controlling variables, and design a controller, the experimental results verify the feasibility and effectiveness of this control method.
Wales, R. O. (Editor)
Attitude control is reviewed, encompassing the attitude control subsystem, spacecraft attitude precision pointing and slewing adaptive control experiment, and RF interferometer experiment. The spacecraft propulsion system (SPS) is discussed, including subsystem, SPS design description and validation, orbital operations and performance, in-orbit anomalies and contingency operations, and the cesium bombardment ion engine experiment. Thruster failure due to plugging of the propellant feed passages, a major cause for mission termination, are considered among the critical generic failures on the satellite.
Full Text Available A hierarchical controller design based on nonlinear H∞ theory and backstepping technique is developed for a nonlinear and coupled dynamic attitude system using conventional quaternion based method. The derived controller combines the attractive features of H∞ optimal controller and the advantages of the backstepping technique leading to a control law which avoids winding phenomena. Performance issues of the controller are illustrated in a simulation study made for a four-rotor vertical take-off and landing (VTOL aerial robot prototype known as the quadrotor aircraft.
Full Text Available In this paper, attitude coordinated tracking control algorithms for multiple spacecraft formation are investigated with consideration of parametric uncertainties, external disturbances, communication delays and actuator saturation. Initially, a sliding mode delay-dependent attitude coordinated controller is proposed under bounded external disturbances. However, neither inertia uncertainty nor actuator constraint has been taken into account. Then, a robust saturated delay-dependent attitude coordinated control law is further derived, where uncertainties and external disturbances are handled by Chebyshev neural networks (CNN. In addition, command filter technique is introduced to facilitate the backstepping design procedure, through which actuator saturation problem is solved. Thus the spacecraft in the formation are able to track the reference attitude trajectory even in the presence of time-varying communication delays. Rigorous analysis is presented by using Lyapunov-Krasovskii approach to demonstrate the stability of the closed-loop system under both control algorithms. Finally, the numerical examples are carried out to illustrate the efficiency of the theoretical results.
Adirelle C. Santana
Full Text Available This article has discussed the development of a three-axis attitude digital controller for an artificial satellite using a digital signal processor. The main motivation of this study is the attitude control system of the satellite Multi-Mission Platform, developed by the Brazilian National Institute for Space Research for application in different sort of missions. The controller design was based on the theory of the Linear Quadratic Gaussian Regulator, synthesized from the linearized model of the motion of the satellite, i.e., the kinematics and dynamics of attitude. The attitude actuators considered in this study are pairs of cold gas jets powered by a pulse width/pulse frequency modulator. In the first stage of the project development, a system controller for continuous time was studied with the aim of testing the adequacy of the adopted control. The next steps had included an analysis of discretization techniques, the setting time of sampling rate, and the testing of the digital version of the Linear Quadratic Gaussian Regulator controller in the MATLAB/SIMULINK. To fulfill the study, the controller was implemented in a digital signal processor, specifically the Blackfin BF537 from Analog Devices, along with the pulse width/pulse frequency modulator. The validation tests used a scheme of co-simulation, where the model of the satellite was simulated in MATLAB/SIMULINK, while the controller and modulator were processed in the digital signal processor with a tool called Processor-In-the-Loop, which acted as a data communication link between both environments.function and required time to achieve a given mission accuracy are determined, and results are provided as illustration.
Full Text Available This paper aims to develop a novel attitude determination system aided by polarization sensor. An improved heading angle function is derived using the perpendicular relationship between directions of E-vector of linearly polarized light and solar vector in the atmospheric polarization distribution model. The Extended Kalman filter (EKF with quaternion differential equation as a dynamic model is applied to fuse the data from sensors. The covariance functions of filter process and measurement noises are deduced in detail. The indoor and outdoor tests are conducted to verify the validity and feasibility of proposed attitude determination system. The test results showed that polarization sensor is not affected by magnetic field, thus the proposed system can work properly in environments containing the magnetic interference. The results also showed that proposed system has higher measurement accuracy than common attitude determination system and can provide precise parameters for Unmanned Aerial Vehicle (UAV flight control. The main contribution of this paper is implementation of the EKF for incorporating the self-developed polarization sensor into the conventional attitude determination system. The real-world experiment with the quad-rotor proved that proposed system can work in a magnetic interference environment and provide sufficient accuracy in attitude determination for autonomous navigation of vehicle.
Full Text Available Attitude stability analysis and robust control algorithms for spacecrafts orbiting irregular asteroids are investigated in the presence of model uncertainties and external disturbances. Rigid spacecraft nonlinear attitude models are considered and detailed attitude stability analysis of spacecraft subjected to the gravity gradient torque in an irregular central gravity field is included in retrograde orbits and direct orbits using linearized system model. The robust adaptive backstepping sliding mode control laws are designed to make the attitude of the spacecrafts stabilized and responded accurately to the expectation in the presence of disturbances and parametric uncertainties. Numerical simulations are included to illustrate the spacecraft performance obtained using the proposed control laws.
Leve, Frederick A; Peck, Mason A
The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...
Naasz, Bo; Hall, Christopher; Berry, Matthew; Hy-Young, Kim
Small satellites tend to be power-limited, so that actuators used to control the orbit and attitude must compete with each other as well as with other subsystems for limited electrical power. The Virginia Tech nanosatellite project, HokieSat, must use its limited power resources to operate pulsed-plasma thrusters for orbit control and magnetic torque coils for attitude control, while also providing power to a GPS receiver, a crosslink transceiver, and other subsystems. The orbit and attitude control strategies were developed independently. The attitude control system is based on an application of Linear Quadratic Regulator (LQR) to an averaged system of equations, whereas the orbit control is based on orbit element feedback. In this paper we describe the strategy for integrating these two control systems and present simulation results to verify the strategy.
Full Text Available In this paper we present the design of a sliding mode controller for attitude control of spacecraft actuated by three orthogonal reaction wheels. The equilibrium of the closed loop system is proved to be asymptotically stable in the sense of Lyapunov. Due to cases where spacecraft do not have angular velocity measurements, an estimator for the generalized velocity is derived and asymptotic stability is proven for the observer. The approach is tested on an experimental platform with a sphere shaped Autonomous Underwater Vehicle SATellite: AUVSAT, developed at the Norwegian University of Science and Technology.
Ahn, Young Tae
Spacecraft need specific attitude control methods that depend on the mission type or special tasks. The dynamics and the attitude control of a spacecraft with a shifting mass distribution within the system are examined. The behavior and use of conventional attitude control actuators are widely developed and performing at the present time. However, the advantage of a shifting mass distribution concept can complement spacecraft attitude control, save mass, and extend a satellite's life. This can be adopted in practice by moving mass from one tank to another, similar to what an airplane does to balance weight. Using this shifting mass distribution concept, in conjunction with other attitude control devices, can augment the three-axis attitude control process. Shifting mass involves changing the center-of-mass of the system, and/or changing the moments of inertia of the system, which then ultimately can change the attitude behavior of the system. This dissertation consists of two parts. First, the equations of motion for the shifting mass concept (also known as morphing) are developed. They are tested for their effects on attitude control by showing how shifting the mass changes the spacecraft's attitude behavior. Second, a method for optimal mass redistribution is shown using a combinatorial optimization theory under constraints. It closes with a simple example demonstrating an optimal reconfiguration. The procedure of optimal reconfiguration from one mass distribution to another to accomplish attitude control has been demonstrated for several simple examples. Mass shifting could work as an attitude controller for fine-tuning attitude behavior in small satellites. Various constraints can be applied for different situations, such as no mass shift between two tanks connected by a failed pipe or total amount of shifted mass per pipe being set for the time optimum solution. Euler angle changes influenced by the mass reconfiguration are accomplished while stability
de Barcellos, Marcia Dutra; Grunert, Klaus G.; Zhou, Y.
In many countries consumers have shown an increasing interest to the way in which food products are being produced. This study investigates Chinese consumers’ attitudes towards different pig production systems by means of a conjoint analysis. While there has been a range of studies on Western con...... of rural and environmental development, quality aspects, and food safety measures are challenges that must be met by the stakeholders of pig production systems in China....
Full Text Available The modeling and attitude stabilization control problems of a four-rotor vertical takeoff and landing unmanned air vehicle (UAV known as the quadrotor are investigated. The quadrotor’s attitude is represented by the unit quaternion rather than Euler angles to avoid singularity problem. Taking dynamical behavior of motors into consideration and ignoring aerodynamic effect, a nonlinear controller is developed to stabilize the attitude. The control design is accomplished by using backstepping control technique. The proposed control law is based on the compensation for the Coriolis and gyroscope torques. Applying Lyapunov stability analysis proves that the closed-loop attitude system is asymptotic stable. Moreover, the controller can guarantee that all the states of the system are uniformly ultimately bounded in the presence of external disturbance torque. The effectiveness of the proposed control approach is analytically authenticated and also validated via simulation study.
Kascak, Peter E.; Jansen, Ralph H.; Kenny, Barbara; Dever, Timothy P.
A computer simulation of a flywheel energy storage single axis attitude control system is described. The simulation models hardware which will be experimentally tested in the future. This hardware consists of two counter rotating flywheels mounted to an air table. The air table allows one axis of rotational motion. An inertia DC bus coordinator is set forth that allows the two control problems, bus regulation and attitude control, to be separated. Simulation results are presented with a previously derived flywheel bus regulator and a simple PID attitude controller.
The influence of patient attitude toward massage on pressure pain sensitivity and immune system after application of myofascial release in breast cancer survivors: a randomized, controlled crossover study.
Fernández-Lao, Carolina; Cantarero-Villanueva, Irene; Díaz-Rodríguez, Lourdes; Fernández-de-las-Peñas, César; Sánchez-Salado, Carmen; Arroyo-Morales, Manuel
The purpose of this study was to evaluate the influence of patient's attitudes toward massage on pressure pain sensitivity and the immune effects of myofascial release in breast cancer survivors (BCS). Twenty BCS participated. They presented to the laboratory at the same time of the day on 2 occasions separated by 2 weeks. At each session, they received either a myofascial release technique or control (special attention) intervention. Salivary flow rate, cortisol and immunoglobulin A (IgA) concentrations, and α-amylase activity were obtained before and immediately after intervention from saliva samples. Pressure pain thresholds (PPT) over the cervical spine and temporalis muscle were assessed bilaterally. The attitude toward massage (ATOM) scale was collected before the first session in all BCS. The analysis of covariance revealed a significant intervention × time interaction for salivary flow rate (P = .010), but not α-amylase (P = .111), IgA (P = .655), and cortisol (P = .363) in favor of the experimental group: BCS exhibited an increase of salivary flow rate after myofascial release intervention. When the ATOM scale was included in the analysis, significant influence on IgA (P = .001) was found: BCS with positive attitude had a significant increase in IgA (P > .05). The analysis of covariance did not find a significant intervention × time interaction for PPT over the cervical spine or temporalis muscle, with no effect of ATOM scales for PPT (P > .05). The current study suggests that myofascial release may lead to an immediate increase in salivary flow rate in BCS with cancer-related fatigue. We also found that the effect of myofascial release on immune function was modulated by a positive patient's attitude toward massage. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.
Sanders, Devon S.; Heater, Daniel L.; Peeples, Steven R.; Sules. James K.; Huang, Po-Hao Adam
A cubesat attitude control system (ACS) was designed at the NASA Marshall Space Flight Center (MSFC) to provide sub-degree pointing capabilities using low cost, COTS attitude sensors, COTS miniature reaction wheels, and a developmental micro-propulsion system. The ACS sensors and actuators were integrated onto a 3D-printed plastic 3U cubesat breadboard (10 cm x 10 cm x 30 cm) with a custom designed instrument board and typical cubesat COTS hardware for the electrical, power, and data handling and processing systems. In addition to the cubesat development, a low-cost air bearing was designed and 3D printed in order to float the cubesat in the test environment. Systems integration and verification were performed at the MSFC Small Projects Rapid Integration & Test Environment laboratory. Using a combination of both the miniature reaction wheels and the micro-propulsion system, the open and closed loop control capabilities of the ACS were tested in the Flight Robotics Laboratory. The testing demonstrated the desired sub-degree pointing capability of the ACS and also revealed the challenges of creating a relevant environment for development testin
Ivanov, D. S.; Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Doronin, D. M.; Ovchinnikov, A. V.
Attitude motion of a satellite equipped with magnetic control system is considered. System comprises of three magnetorquers and one three-axis magnetometer. Satellite is stabilized in orbital reference frame using PD controller and extended Kalman filter. Three-axis attitude is analyzed numerically with advanced assumptions: inertia tensor uncertainty, disturbances of unknown nature, magnetometer errors are taken into account. Stabilization and determination accuracy dependence on orbit inclination is studied.
of the work was on the class of periodic systems reflecting orbital motion of the satellite. In addition to a theoretical treatment, the thesis contains a large portion of application considerations. The controllers developed were implemented for the Danish Ørsted satellite. The control concept considered......The primary purpose of this work was to develop control laws for three axis stabilization of a magnetic actuated satellite. This was achieved by a combination of linear and nonlinear system theory. In order to reach this goal new theoretical results were produced in both fields. The focus...... was that interaction between the Earth's magnetic field and a magnetic field generated by a set of coils in the satellite can be used for actuation. Magnetic torquing was found attractive for generation of control torques on small satellites, since magnetic control systems are relatively lightweight, require low power...
Kenny, Barbara H.
This presentation discussed the flywheel technology development work that is ongoing at NASA GRC with a particular emphasis on the flywheel system control. The "field orientation" motor/generator control algorithm was discussed and explained. The position-sensorless angle and speed estimation algorithm was presented. The motor current response to a step change in command at low (10 kRPM) and high (60 kRPM) was discussed. The flywheel DC bus regulation control was explained and experimental results presented. Finally, the combined attitude control and energy storage algorithm that controls two flywheels simultaneously was presented. Experimental results were shown that verified the operational capability of the algorithm. shows high speed flywheel energy storage (60,000 RPM) and the successful implementation of an algorithm to simultaneously control both energy storage and a single axis of attitude with two flywheels. Overall, the presentation demonstrated that GRC has an operational facility that
Sunkel, John W.; Singh, Ramen P.; Vengopal, Ravi
The Space Station Attitude Control System software test-bed provides a rigorous environment for the design, development and functional verification of GN and C algorithms and software. The approach taken for the simulation of the vehicle dynamics and environmental models using a computationally efficient algorithm is discussed. The simulation includes capabilities for docking/berthing dynamics, prescribed motion dynamics associated with the Mobile Remote Manipulator System (MRMS) and microgravity disturbances. The vehicle dynamics module interfaces with the test-bed through the central Communicator facility which is in turn driven by the Station Control Simulator (SCS) Executive. The Communicator addresses issues such as the interface between the discrete flight software and the continuous vehicle dynamics, and multi-programming aspects such as the complex flow of control in real-time programs. Combined with the flight software and redundancy management modules, the facility provides a flexible, user-oriented simulation platform.
Barrows, D.; Bedell, H.
It is pointed out that on-orbit configuration variability is expected to be a characteristic of a space station. The implementation of such a chracteristic will present reboost and thruster control system designers with a number of new challenges. The primary requirement for the space station orbit reboost (or orbit keeping) system is to ensure system viability for extended duration and prevent an uncontrolled reentry as with Skylab. For a station in a low earth orbit, earodynamic drag will be sufficient to cause relatively quick orbit altitude decay. A propulsion system is, therefore, needed to counteract the aerodynamic drag forces and to boost the vehicle to the desired orbit altitudes. A description is given of a typical reboost operational procedure and propellant requirements. Attention is given to thruster control systems, and aspects of reboost guidance.
Full Text Available A novel attitude tracking control scheme is presented for overactuated spacecraft to address the attitude stabilization problem in presence of reaction wheel installation deviation, external disturbance and uncertain mass of moment inertia. An adaptive sliding mode control technique is proposed to track the uncertainty. A Lyapunov-based analysis shows that the compensation control law can guarantee that the desired attitude trajectories are followed in finite-time. The key feature of the proposed control strategy is that it globally asymptotically stabilizes the system, even in the presence of reaction wheel installation deviation, external disturbances, and uncertain mass of moment inertia. The attitude track performance using the proposed finite-time compensation control is evaluated through a numerical example.
Bramberg, B.; Croft, J.
The way in which COBE (launched by the SS in late 1982) performs its attitude control is described, along with the design of its on-orbit system. COBE, to be situated in a 900 km high, sun-synchronous orbit, contains two unique control features: (1) the orientation of the spinning satellite is controlled to a sun-normal attitude in the sun/local vertical plane; and (2) pitch and roll control is maintained by a unique triaxial arrangement of reaction wheels, magnetic torque bars and sensors, located in the body's tranverse plane. Inherent in this triaxial configuration concept is a built-in redundancy that will maintain attitude control in the event of any single-point sensor/actuator component failure. Each of the three control drive electronics operates independently and directly of a system of dedicated sensors. This system functions independently of a computer or an ephemeris communication link, leading to greater reliability.
Reyhanoglu, Mahmut; Mcclamroch, N. Harris
An attitude control strategy for maneuvers of an interconnection of planar bodies in space is developed. It is assumed that there are no exogeneous torques and that torques generated by joint motors are used as means of control so that the total angular momentum of the multibody system is a constant, assumed to be zero. The control strategy utilizes the nonintegrability of the expression for the angular momentum. Large angle maneuvers can be designed to achieve an arbitrary reorientation of the multibody system with respect to an inertial frame. The theoretical background for carrying out the required maneuvers is summarized.
Hoffman, D. P.; Berkery, E. A.
The first satellite (HEAO-1) in the High Energy Astronomy Observatory Program series was launched successfully on Aug. 12, 1977. To date it has completed over nine months of orbital operation in a science data gathering mode. During this period all attitude control modes have been exercised and all primary mission objectives have been achieved. This paper highlights the characteristics of the attitude control subsystem design and compares the predicted performance with the actual flight operations experience. Environmental disturbance modeling, component hardware/software characteristics, and overall attitude control performance are reviewed and are found to compare very well with the prelaunch analytical predictions. Brief comments are also included regarding the operations aspects of the attitude control subsystem. The experience in this regard demonstrates the effectiveness of the design flexibility afforded by the presence of a general purpose digital processor in the subsystem flight hardware implementation.
National Aeronautics and Space Administration — A new pulsed electric thruster, named "pulsed electrogasdynamic thruster," for attitude control and orbit maneuver is proposed. In this thruster, propellant gas is...
National Aeronautics and Space Administration — In the Phase I program we successfully demonstrated the feasibility of the Pulsed ElectroGasdynamic (PEG) thruster for attitude control and orbital maneuvering. In...
The inertial attitude control system designed for the Voyager spacecraft, which will carry out flybys of Jupiter and Saturn in 1979 and 1981, respectively, is described. The attitude of the spacecraft in three-dimensional space will be measured by a Dry Inertial Reference Unit (DIRU) based on three identical two-degree-of-freedom dry gyros. A software estimation process has been developed to use DIRU data and other information to obtain optimum estimates of spacecraft position, velocity, and acceleration. The attitude of the spacecraft is corrected using these estimates by activating hydrazine thrusters. The operation of dry gyros is discussed, together with the network compensation techniques used in their associated capture loop to obtain a capture capability of 8 deg/sec and a frequency response of 10 Hz (3-dB point). The control law and estimation process are examined. Results of computer simulation studies of the performance of the attitude control system are presented.
This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students......, over a period of only 18 months. This paper emphasises on the trade-offs required to build an operational ADCS system within such a rapidly developing project....
This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students......, over a period of only 18 months. This paper emphasises on the trade-offs required to build an operational ADCS system within such a rapidly developing project....
Full Text Available The problem of finite-time control for attitude tracking maneuver of a rigid spacecraft is investigated. External disturbance, unknown inertia parameters are addressed. As stepping stone, a sliding mode controller is designed. It requires the upper bound of the lumped uncertainty including disturbance and inertia matrix. However, this upper bound may not be easily obtained. Therefore, an adaptive sliding mode control law is then proposed to release that drawback. Adaptive technique is applied to estimate that bound. It is proved that the closed-loop attitude tracking system is finite-time stable. The tracking errors of the attitude and the angular velocity are asymptotically stabilized. Moreover, the upper bound on the lumped uncertainty can be exactly estimated in finite time. The attitude tracking performance with application of the control scheme is evaluated through a numerical example.
Weng, Liguo; Xia, Min; Wang, Wei; Liu, Qingshan
This paper addresses the problem of the crew exploration vehicle (CEV) attitude control. CEVs are NASA's next-generation human spaceflight vehicles, and they use reaction control system (RCS) jet engines for attitude adjustment, which calls for control algorithms for firing the small propulsion engines mounted on vehicles. In this work, the resultant CEV dynamics combines both actuation and attitude dynamics. Therefore, it is highly nonlinear and even coupled with significant uncertainties. To cope with this situation, a neural-immunology/memory network is proposed. It is inspired by the human memory and immune systems. The control network does not rely on precise system dynamics information. Furthermore, the overall control scheme has a simple structure and demands much less computation as compared with most existing methods, making it attractive for real-time implementation. The effectiveness of this approach is also verified via simulation.
is the sum of the gradient of the potential energy and the dissipative force. It is shown that this control law makes the system uniformly asymptotically stable to the desired reference point. Three problems were addressed in the paper: spacecraft stabilization in the inertial frame, libration damping...... with the use of electromagnetic coils and a slew maneuver with an additional objective of avoiding undesirable regions e.g. causing blindness of optical sensors...
Nicholson, Mark; Markley, F.; Seidewitz, E.
The mathematical specifications of Release 4.0 of the Attitude Determination Error Analysis System (ADEAS), which provides a general-purpose linear error analysis capability for various spacecraft attitude geometries and determination processes, are presented. The analytical basis of the system is presented. The analytical basis of the system is presented, and detailed equations are provided for both three-axis-stabilized and spin-stabilized attitude sensor models.
Zou, An-Min; Dev Kumar, Krishna; Hou, Zeng-Guang
This paper investigates the problem of output feedback attitude control of an uncertain spacecraft. Two robust adaptive output feedback controllers based on Chebyshev neural networks (CNN) termed adaptive neural networks (NN) controller-I and adaptive NN controller-II are proposed for the attitude tracking control of spacecraft. The four-parameter representations (quaternion) are employed to describe the spacecraft attitude for global representation without singularities. The nonlinear reduced-order observer is used to estimate the derivative of the spacecraft output, and the CNN is introduced to further improve the control performance through approximating the spacecraft attitude motion. The implementation of the basis functions of the CNN used in the proposed controllers depends only on the desired signals, and the smooth robust compensator using the hyperbolic tangent function is employed to counteract the CNN approximation errors and external disturbances. The adaptive NN controller-II can efficiently avoid the over-estimation problem (i.e., the bound of the CNNs output is much larger than that of the approximated unknown function, and hence, the control input may be very large) existing in the adaptive NN controller-I. Both adaptive output feedback controllers using CNN can guarantee that all signals in the resulting closed-loop system are uniformly ultimately bounded. For performance comparisons, the standard adaptive controller using the linear parameterization of spacecraft attitude motion is also developed. Simulation studies are presented to show the advantages of the proposed CNN-based output feedback approach over the standard adaptive output feedback approach.
Kenny, Barbara H.; Jansen, Ralph; Kascak, Peter; Dever, Timothy; Santiago, Walter
The energy storage and attitude control subsystems of the typical satellite are presently distinct and separate. Energy storage is conventionally provided by batteries, either NiCd or NiH, and active attitude control is accomplished with control moment gyros (CMGs) or reaction wheels. An overall system mass savings can be realized if these two subsystems are combined using multiple flywheels for simultaneous kinetic energy storage and momentum transfer. Several authors have studied the control of the flywheels to accomplish this and have published simulation results showing the feasibility and performance. This paper presents the first experimental results showing combined energy storage and momentum control about a single axis using two flywheels.
Hall, Charles E.; Panossian, Hagop V.
The Vehicle Control Systems Team at Marshall Space Flight Center, Structures and Dynamics Laboratory, Guidance and Control Systems Division is designing, under a cooperative agreement with Lockheed Martin Skunkworks, the Ascent, Transition, and Entry flight attitude control systems for the X-33 experimental vehicle. Test flights, while suborbital, will achieve sufficient altitudes and Mach numbers to test Single Stage To Orbit, Reusable Launch Vehicle technologies. Ascent flight control phase, the focus of this paper, begins at liftoff and ends at linear aerospike main engine cutoff (MECO). The X-33 attitude control system design is confronted by a myriad of design challenges: a short design cycle, the X-33 incremental test philosophy, the concurrent design philosophy chosen for the X-33 program, and the fact that the attitude control system design is, as usual, closely linked to many other subsystems and must deal with constraints and requirements from these subsystems. Additionally, however, and of special interest, the use of the linear aerospike engine is a departure from the gimbaled engines traditionally used for thrust vector control (TVC) in launch vehicles and poses certain design challenges. This paper discusses the unique problem of designing the X-33 attitude control system with the linear aerospike engine, requirements development, modeling and analyses that verify the design.
Wisniewski, Rafal; Kulczycki, P.
A configuration consisting of a star camera, four reaction wheels and magnetorquers for momentum unloading has become standard for many spacecraft missions. This popularity has motivated numerous agencies and private companies to initiate work on the design of an imbedded attitude control system...... realized on an integrated circuit. This paper considers two issues: slew maneuver with a feature of avoiding direct exposure of the camera's CCD chip to the Sun %, three-axis attitude control and optimal control torque distribution in a reaction wheel assembly. The attitude controller is synthesized...... applying the energy shaping technique, where the desired potential function is carefully designed using a physical insight into the nature of the problem. The system stability is thoroughly analyzed and the control performance simulated...
Modi, V. J.
This paper briefly reviews attitude dynamics and trajectory mechanics of spacecraft in the presence of environmental forces with particular emphasis on the solar radiation induced pressure and thermal effects on attitude dynamics. In general, the effect is destabilizing as indicated by a significant reduction in the size of the limiting integral manifold. However, several semi-passive controllers have been proposed which can use the environmental forces to advantage in stabilizing the system. Furthermore, the solar radiation-induced forces can be used to advantage for propulsion and trajectory transfer. Examples of contemporary interest illustrate effectiveness of the concepts in achieving desired attitude and trajectory.
Lorenz, Ralph D.; Burk, Thomas A.
The plumes of Enceladus are of interest both as a geophysical phenomenon, and as an astrobiological opportunity for sampling internal material. Here we report measurements of the total mass density (gas plus dust, a combination not reported before except in the engineering literature) deduced from telemetry of Cassini's Attitude and Articulation Control System (AACS), as the spacecraft's thrusters or reaction wheels worked to maintain the desired attitude in the presence of drag torques during close flybys. The drag torque shows good agreement with the water vapor density measured by other instruments during the E5 encounter, but indicates a rather higher mass density on other passes (E3, E14), possibly indicating variations in gas composition and/or gas:dust ratio. The spacecraft appears to have intercepted about 0.2 g of material, on flyby E21 in October 2015 indicating a peak mass density of ∼5.5 × 10-11 kg m-3, the highest of all the flybys measured (E3, E5, E7, E9, E14, E21).
Full Text Available The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.
Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming
The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.
Bahrami, K. A.
A major challenge of the Mariner Jupiter-Saturn '77 spacecraft was devising a suboptimal attitude controller that could meet the demanding mission requirements. The challenge was met by implementing a discrete stochastic controller for a specially designed onboard computer. The paper describes the design and operation of the controller, based on a simple model of spacecraft dynamics. Two types of cruising modes are considered: inertial cruise, where spacecraft attitude is determined from gyro position outputs, and celestial cruise, where position information is obtained from sun sensors and a star tracker. These two cruise modes under conditions of disturbances were simulated on computer, and the results showed that the controller maintained the spacecraft attitude with low rates. An appendix gives details on the single-step predictor.
Full Text Available In this work, we address the problem of global attitude control using direct inertial measurements. When using direct inertial measurement to observe the rigid body attitude, it is shown that due to a geometrical obstruction, it is impossible to achieve global asymptotic stability. In fact, for a particular initial condition the tracking error quaternion converges to a pure imaginary quaternion formed by an eigenvector of a characteristic matrix related to the inertial constant and known vectors. Our proposition consists of adding a dynamic signal to force the rigid body to escape from such a situation. The proposed observer-based controller is synthesized based on a single Lyapunov function and a stability analysis shows that the controller stabilizes globally and asymptotically the rigid body attitude at the desired one. The effectiveness of the proposed observer-based controller is confirmed by simulation results.
Dilssner, F.; Springer, T.; Enderle, W.
On May 27, 2010, the first satellite of the Block II "follow-on" (Block IIF) series, the fourth generation of Global Positioning System (GPS) spacecraft, has been successfully placed into orbit. GPS IIF-1, also referred to as space vehicle number (SVN) 62, has been injected into orbital plane B, slot position 2 of the GPS constellation. After completing three months of comprehensive in-orbit testing, the satellite entered service for the US Air Force (USAF) on August 26, 2010. A little over a year after the inaugural launch of GPS IIF-1, the USAF has now launched the second spacecraft of the IIF series (SVN-63). The IIF series includes a total of 12 satellites: SVN-62 through SVN-73. Despite having many technical advances over their predecessors such as enhanced rubidium frequency standards, more precise and powerful signals and an extended design life, the three-axis stabilized Block IIF satellites follow a completely different yaw attitude scheme, when passing through the Earth's shadow, to the Block IIA and IIR spacecraft. We will describe how high-rate carrier phase and pseudo-range measurements from a global GPS tracking network can be exploited to precisely monitor the yaw attitude behavior of SVN-62 and SVN-63 during their solar eclipse phases. The insights gained from this study have led to the development of a new GPS Block IIF yaw attitude model. We will show that the yaw rate of a Block IIF space vehicle is kept constant to the value needed to get the satellite back to near its nominal attitude when leaving the Earth's shadow and that a IIF satellite being in deep eclipse therefore needs to yaw significantly faster than an eclipsing IIF space vehicle passing only partly through the Earth's shadow. How the satellites' attitude control system (ACS) exactly computes this dynamical yaw rate parameter will be discussed here as well. Moreover, we will report on yaw attitude anomalies occurring when the GPS Block IIF satellites are shaded from the Sun by the
Pimienta-Penalver, Adonis Reinier
A heliogyro solar sail concept, dubbed `HELIOS', is proposed as an alternative to deep space missions without the need for on-board propellant. Although this type of solar sail has existed in concept for several decades, and some previous studies have investigated certain aspects of its operation, a significant amount of research is still needed to analyze the dynamic and control characteristics of the structure under the projected range of orbital conditions. This work presents an improvement upon the existing discrete-mass models of the heliogyro blade, and the extension of its application from a single membrane blade to a fully-coupled approximation of the dynamics of the HELIOS system with multiple spinning membrane blades around a central hub. The incorporation of structural stiffness and external forcing effects into the model is demonstrated to add a further degree of fidelity in simulating the stability properties of the system. Additionally, the approximated dynamics of multiple-blade heliogyro structures are examined under the effect of solar radiation pressure. Lastly, this study evaluates a control algorithm at each blade root to impose structural integrity and attitude control by coordinating well-known helicopter blade pitching profiles.
Full Text Available Micro air vehicles (MAVs have a wide application such as the military reconnaissance, meteorological survey, environmental monitoring, and other aspects. In this paper, attitude and altitude control for Quad-Rotor type MAVs is discussed and analyzed. For the attitude control, a new method by using three gyroscopes and one triaxial accelerometer is proposed to estimate the attitude angle information. Then with the approximate linear model obtained by system identification, Model Reference Sliding Mode Control (MRSMC technique is applied to enhance the robustness. In consideration of the relatively constant altitude model, a Linear Quadratic Gaussian (LQG controller is adopted. The outdoor experimental results demonstrate the superior stability and robustness of the controllers.
control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis attitude control. This paper deals with three-axis stabilization of a low earth orbit satellite. The problem of controlling......Magnetic torquing is attractive as a control principle on small satellites. The actuation principle is to use the interaction between the earth's magnetic field and magnetic field generated by a coil set in the satellite. This control principle is inherently nonlinear, and difficult to use because...... the spacecraft attitude using only magnetic torquing is realized in the form of the sliding mode control. A three dimensional sliding manifold is proposed, and it is shown that the satellite motion on the sliding manifold is asymptotically stable...
Prinzel, Lawrence J., III; Ellis, Kyle E.; Arthur, Jarvis J.; Nicholas, Stephanie N.; Kiggins, Daniel
A Commercial Aviation Safety Team (CAST) study of 18 worldwide loss-of-control accidents and incidents determined that the lack of external visual references was associated with a flight crew's loss of attitude awareness or energy state awareness in 17 of these events. Therefore, CAST recommended development and implementation of virtual day-Visual Meteorological Condition (VMC) display systems, such as synthetic vision systems, which can promote flight crew attitude awareness similar to a day-VMC environment. This paper describes the results of a high-fidelity, large transport aircraft simulation experiment that evaluated virtual day-VMC displays and a "background attitude indicator" concept as an aid to pilots in recovery from unusual attitudes. Twelve commercial airline pilots performed multiple unusual attitude recoveries and both quantitative and qualitative dependent measures were collected. Experimental results and future research directions under this CAST initiative and the NASA "Technologies for Airplane State Awareness" research project are described.
Cui, Hongzheng; Han, Chao; Chen, Pei; Luo, Qinqin
In this paper, a high precision and convenient extension simulation platform for satellite attitude and orbit system is developed, to demonstrate the satellite attitude and orbit system for given space mission, and test the new underdeveloped algorithms for attitude/orbit dynamics, attitude determination, orbit navigation, and attitude/orbit control. The simulation platform is based on Matlab/Simulink software, using the technique of Simulink modeling, importing C/Fortran code in Matlab/Simulink, and embedded Matlab function, with beautiful reusability, inheritability and expansibility. The paper orderly presents the background behind the development of the platform, the platform design architecture and capability, the validity of the platform, the inheritability and expansibility of the platform, the platform implementation example for Chinese weather satellite (FY-3), and the future development for the platform.
Hu, Qinglei; Niu, Guanglin
The main problem addressed is the quaternion-based attitude stabilization control of rigid spacecraft without angular velocity measurements in the presence of external disturbances and reaction wheel friction as well. As a stepping stone, an angular velocity observer is proposed for the attitude control of a rigid body in the absence of angular velocity measurements. The observer design ensures finite-time convergence of angular velocity state estimation errors irrespective of the control torque or the initial attitude state of the spacecraft. Then, a novel finite-time control law is employed as the controller in which the estimate of the angular velocity is used directly. It is then shown that the observer and the controlled system form a cascaded structure, which allows the application of the finite-time stability theory of cascaded systems to prove the finite-time stability of the closed-loop system. A rigorous analysis of the proposed formulation is provided and numerical simulation studies are presented to help illustrate the effectiveness of the angular-velocity observer for rigid spacecraft attitude control. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Kline-Schoder, Robert J.
Tethered spacecraft possess unique dynamic characteristics which make them advantageous for certain classes of experiments. One use for which tethers are particularly well suited is to provide an isolated platform for spaceborne observatories. The advantages of tethering a pointing platform 1 or 2 km from a space shuttle or space station are that, compared to placing the observatory on the parent spacecraft, vibrational disturbances are attenuated and contamination is eliminated. In practice, all satellites have some requirement on the attitude control of the spacecraft, and tethered satellites are no exception. It has previously been shown that conventional means of performing attitude control for tethered satellites are insufficient for any mission with pointing requirements more stringent than about 1 deg. This is due mainly to the relatively large force applied by the tether to the spacecraft. A particularly effective method of implementing attitude control for tethered satellites is to use this tether tension force to generate control torques by moving the tether attach point relative to the subsatellite center of mass. A demonstration of this attitude control technique on an astrophysical pointing platform has been proposed for a space shuttle flight test project and is referred to as the Kinetic Isolation Tether Experiment (KITE).
Murphy, Kelly J.; Brauckmann, Gregory J.; Paschal, Keith B.; Chan, David T.; Walker, Eric L.; Foley, Robert; Mayfield, David; Cross, Jared
Current Orion Launch Abort Vehicle (LAV) configurations use an eight-jet, solid-fueled Attitude Control Motor (ACM) to provide required vehicle control for all proposed abort trajectories. Due to the forward position of the ACM on the LAV, it is necessary to assess the effects of jet-interactions (JI) between the various ACM nozzle plumes and the external flow along the outside surfaces of the vehicle. These JI-induced changes in flight control characteristics must be accounted for in developing ACM operations and LAV flight characteristics. A test program to generate jet interaction aerodynamic increment data for multiple LAV configurations was conducted in the NASA Ames and NASA Langley Unitary Plan Wind Tunnels from August 2007 through December 2009. Using cold air as the simulant gas, powered subscale models were used to generate interaction data at subsonic, transonic, and supersonic test conditions. This paper presents an overview of the complete ACM JI experimental test program for Orion LAV configurations, highlighting ACM system modeling, nozzle scaling assumptions, experimental test techniques, and data reduction methodologies. Lessons learned are discussed, and sample jet interaction data are shown. These data, in conjunction with computational predictions, were used to create the ACM JI increments for all relevant flight databases.
Keshtkar, Sajjad; Moreno, Jaime A.; Kojima, Hirohisa; Uchiyama, Kenji; Nohmi, Masahiro; Takaya, Keisuke
This paper presents a new and improved concept of recently proposed two-degrees of freedom spherical stabilizer for triaxial orientation of microsatellites. The analytical analysis of the advantages of the proposed mechanism over the existing inertial attitude control devices are introduced. The extended equations of motion of the stabilizing satellite including the spherical gyroscope, for control law design and numerical simulations, are studied in detail. A new control algorithm based on continuous high-order sliding mode algorithms, for managing the torque produced by the stabilizer and therefore the attitude control of the satellite in the presence of perturbations/uncertainties, is presented. Some numerical simulations are carried out to prove the performance of the proposed mechanism and control laws.
Burk, Thomas A.
The Cassini mission at Saturn will come to an end in the spring and summer of 2017 with a series of 22 orbits that will dip inside the rings of Saturn. These are called proximal orbits and will conclude with spacecraft disposal into the atmosphere of the ringed world on September 15, 2017. These unique orbits that cross the ring plane only a few thousand kilometers above the cloud tops of the planet present new attitude control challenges for the Cassini operations team. Crossing the ring plane so close to the inner edge of the rings means that the Cassini orientation during the crossing will be tailored to protect the sensitive electronics bus of the spacecraft. This orientation will put the sun sensors at some extra risk so this paper discusses how the team prepares for dust hazards. Periapsis is so close to the planet that spacecraft controllability with RCS thrusters needs to be evaluated because of the predicted atmospheric torque near closest approach to Saturn. Radiation during the ring plane crossings will likely trigger single event transients in some attitude control sensors. This paper discusses how the attitude control team deals with radiation hazards. The angular size and unique geometry of the rings and Saturn near periapsis means that star identification will be interrupted and this paper discusses how the safe mode attitude is selected to best deal with these large bright bodies during the proximal orbits.
Methods: To assess students' knowledge and attitudes regarding infection prevention and control and their sources of information, a self-administered questionnaire was used to look at standard precautions especially hands hygiene. Results: One hundred sixty two students participated in this study of which 31 were ...
Methods: To assess students' knowledge and attitudes regarding infection prevention and control and their sources of information, a self-administered questionnaire was used to look at standard precautions especially hands hygiene. Results: One hundred sixty two ... vehicles as food or water. Exposure to infectious.
Full Text Available This paper presents the finite-time attitude control problem for reentry vehicle with redundant actuators in consideration of planet uncertainties and external disturbances. Firstly, feedback linearization technique is used to cancel the nonlinearities of equations of motion to construct a basic mode for attitude controller. Secondly, two kinds of time-varying sliding mode control methods with disturbance observer are integrated with the basic mode in order to enhance the control performance and system robustness. One method is designed based on boundary layer technique and the other is a novel second-order sliding model control method. The finite-time stability analyses of both resultant closed-loop systems are carried out. Furthermore, after attitude controller produces the torque commands, an optimization control allocation approach is introduced to allocate them into aerodynamic surface deflections and on-off reaction control system thrusts. Finally, the numerical simulation results demonstrate that both of the time-varying sliding mode control methods are robust to uncertainties and disturbances without chattering phenomenon. Moreover, the proposed second-order sliding mode control method possesses better control accuracy.
Full Text Available In this study, a Hardware-In-the-Loop (HIL simulator using thrusters is developed to validate the spacecraft attitude system. To control the attitude of the simulator, eight cold gas thrusters are aligned with roll, pitch and yaw axis. Also linear actuators are applied to the HIL simulator for automatic mass balancing to compensate the center of mass offset from the center of rotation. The HIL simulator consists of an embedded computer (Onboard PC for simulator system control, a wireless adapter for wireless network, a rate gyro sensor to measure 3-axis attitude of the simulator, an inclinometer to measure horizontal attitude, and a battery set to supply power for the simulator independently. For the performance test of the HIL simulator, a bang-bang controller and Pulse-Width Pulse-Frequency (PWPF modulator are evaluated successfully. The maneuver of 68 deg. in yaw axis is tested for the comparison of the both controllers. The settling time of the bang -bang controller is faster than that of the PWPF modulator by six seconds in the experiment. The required fuel of the PWPF modulator is used as much as 51% of bang-bang controller in the experiment. Overall, the HIL simulator is appropriately developed to validate the control algorithms using thrusters.
the EC-45 are listed in Table 7.4(a) while an image of this motor is shown in Figure 7.1(a). The shear contrast in size of the EC-16 and EC-45...Spacecraft Attitude and Orbit Control Systems, 1997, pp. 221–228.  Hebner, R., B. J. and Walls , A., “Flywheel Batteries Come Around Again,” IEEE...Achieve- ments,” Powerpoint Presentation.  Lappas, V., Ooisthuizen, P., Madle, P., Cowie, L., Yuksel, G., and Fertin, D., “De- sign, Analysis
Bekkeng, Jan Kenneth; Booij, Wilfred; Moen, J.
Spacecraft attitude (orientation) information is needed in order to transform scientific vector measurements in the reference frame of the rocket into a more meaningful Earth-fixed reference frame. By fusing data from a 3-axial magnetometer, a sun sensor and three rate gyros the rockets attitude can be determined (reconstructed). Since the system does not need to determine the attitude in real time (the attitude data is not used to control the rocket orientation), all data from the attitude sensors can be transmitted back to ground, where they are fused to estimate an absolute orientation of the rocket. A prototype inertial measurement unit and a miniature high accuracy lens-less sun sensor for spinning rocket is under development. A test version of both instruments will be launched on a single stage Hotel Payload sounding rocket from Andøya Rocket Range in July 2005.
Somov, Ye.; Butyrin, S.; Somov, S.; Somova, T.; Testoyedov, N.; Rayevsky, V.; Titov, G.; Yakimov, Ye.; Ovchinnikov, A.; Mathylenko, M.
We consider a small information satellite which may be placed on an orbit with altitude from 600 up to 1000 km. The satellite attitude and orbit control system contains a strap-down inertial navigation system, cluster of four reaction wheels, magnetic driver and a correcting engine unit with eight electro-reaction engines. We study problems on design of algorithms for spatial guidance, in-flight identification and adaptive-robust control of the satellite motion on sun-synchronous orbit.
Full Text Available Displaced solar orbits for spacecraft propelled by electric sails are investigated. Since the propulsive thrust is induced by the sail attitude, the orbital and attitude dynamics of electric-sail-based spacecraft are coupled and required to be investigated together. However, the coupled dynamics and control of electric sails have not been discussed in most published literatures. In this paper, the equilibrium point of the coupled dynamical system in displaced orbit is obtained, and its stability is analyzed through a linearization. The results of stability analysis show that only some of the orbits are marginally stable. For unstable displaced orbits, linear quadratic regulator is employed to control the coupled attitude-orbit system. Numerical simulations show that the proposed strategy can control the coupled system and a small torque can stabilize both the attitude and orbit. In order to generate the control force and torque, the voltage distribution problem is studied in an optimal framework. The numerical results show that the control force and torque of electric sail can be realized by adjusting the voltage distribution of charged tethers.
Hawk, Stephen R.
Describes study that was conducted to investigate the relationship between locus of control and user attitude toward computer based information systems (CBIS) used at work. The impact of user involvement is examined, the hypotheses tested are described, and implications for introducing CBIS into organizations are discussed. (14 references) (LRW)
A system which analyzes telemetry and evaluates hypotheses to explain any anomalies that are observed is described. Results achieved from a sample set of failure cases are presented, followed by a brief discussion of the benefits derived from this approach.
Rodden, John James (Inventor); Price, Xenophon (Inventor); Carrou, Stephane (Inventor); Stevens, Homer Darling (Inventor)
A control system for providing attitude control in spacecraft. The control system comprising a primary attitude reference system, a secondary attitude reference system, and a hyper-complex number differencing system. The hyper-complex number differencing system is connectable to the primary attitude reference system and the secondary attitude reference system.
Xue, Dong-yang; Wu, Zhi-liang; Qi, Er-mai; Wang, Yan-hui; Wang, Shu-xin
Application of multiple hybrid underwater gliders (HUGs) is a promising method for large scale, long-term ocean survey. Attitude coordination has become a requisite for task execution of multi-HUG formation. In this paper, a multibody model is presented for attitude coordination among agents in the HUG formation. The HUG formation is regarded as a multi-rigid body system. The interaction between agents in the formation is described by artificial potential field (APF) approach. Attitude control torque is composed of a conservative torque generated by orientation potential field and a dissipative term related with angular velocity. Dynamic modeling of the multibody system is presented to analyze the dynamic process of the HUG formation. Numerical calculation is carried out to simulate attitude synchronization with two kinds of formation topologies. Results show that attitude synchronization can be fulfilled based on the multibody method described in this paper. It is also indicated that different topologies affect attitude control quality with respect to energy consumption and adjusting time. Low level topology should be adopted during formation control scheme design to achieve a better control effect.
Franchi, Loris; Feruglio, Lorenzo; Mozzillo, Raffaele; Corpino, Sabrina
In recent years, thanks to the increase of the know-how on machine-learning techniques and the advance of the computational capabilities of on-board processing, expensive computing algorithms, such as Model Predictive Control, have begun to spread in space applications even on small on-board processor. The paper presents an algorithm for an optimal fault recovery of a 3U CubeSat, developed in MathWorks Matlab & Simulink environment. This algorithm involves optimization techniques aiming at obtaining the optimal recovery solution, and involves a Model Predictive Control approach for the attitude control. The simulated system is a CubeSat in Low Earth Orbit: the attitude control is performed with three magnetic torquers and a single reaction wheel. The simulation neglects the errors in the attitude determination of the satellite, and focuses on the recovery approach and control method. The optimal recovery approach takes advantage of the properties of magnetic actuation, which gives the possibility of the redistribution of the control action when a fault occurs on a single magnetic torquer, even in absence of redundant actuators. In addition, the paper presents the results of the implementation of Model Predictive approach to control the attitude of the satellite.
Wisniewski, Rafal; Stoustrup, Jakob
A control synthesis for a spacecraft equipped with a set of magnetorquer coils is addressed. The electromagnetic actuation is particularly attractive for small low-cost spacecraft missions, due to their relatively low price, high reliability, light weight, and low power consumption. The interaction...... between the Earth´s magnetic field and an artificial magnetic field generated by the coils produces a control torque. The magnetic attitude control is intrinsically periodic due to cyclic variation of the geomagnetic field in orbit. The control performance is specified by the generalized H2 operator norm...
Full Text Available An attitude control strategy based on Ziegler-Nichols rules for tuning PD (proportional-derivative parameters of quadrotor helicopters is presented to solve the problem that quadrotor tends to be instable. This problem is caused by the narrow definition domain of attitude angles of quadrotor helicopters. The proposed controller is nonlinear and consists of a linear part and a nonlinear part. The linear part is a PD controller with PD parameters tuned by Ziegler-Nichols rules and acts on the quadrotor decoupled linear system after feedback linearization; the nonlinear part is a feedback linearization item which converts a nonlinear system into a linear system. It can be seen from the simulation results that the attitude controller proposed in this paper is highly robust, and its control effect is better than the other two nonlinear controllers. The nonlinear parts of the other two nonlinear controllers are the same as the attitude controller proposed in this paper. The linear part involves a PID (proportional-integral-derivative controller with the PID controller parameters tuned by Ziegler-Nichols rules and a PD controller with the PD controller parameters tuned by GA (genetic algorithms. Moreover, this attitude controller is simple and easy to implement.
Full Text Available Attitude control is the inner-loop and the most important part of the automatic flight control system of an unmanned aerial vehicle (UAV. The information fusion-based optimal control method is applied in a UAV flight control system in this work. Firstly, a nonlinear model of alterable thrust direction UAV (ATD-UAV is established and linearized for controller design. The longitudinal controller and lateral controller are respectively designed based on information fusion-based optimal control, and then the information fusion flight control system is built up. Finally, the simulation of a nonlinear model described as ATD-UAV is carried out, the results of which show the superiority of the information fusion-based control strategy when compared to the single-loop design method. We also show that the ATD technique improves the anti-disturbance capacity of the UAV.
Guo, Xiaoting; Sun, Changku; Wang, Peng; Lu, Huang
To determination relative attitude between two space objects on a rocking base, an integrated system based on vision and dual IMU (inertial determination unit) is built up. The determination system fuses the attitude information of vision with the angular determinations of dual IMU by extended Kalman filter (EKF) to obtain the relative attitude. One IMU (master) is attached to the measured motion object and the other (slave) to the rocking base. As the determination output of inertial sensor is relative to inertial frame, thus angular rate of the master IMU includes not only motion of the measured object relative to inertial frame but also the rocking base relative to inertial frame, where the latter can be seen as redundant harmful movement information for relative attitude determination between the measured object and the rocking base. The slave IMU here assists to remove the motion information of rocking base relative to inertial frame from the master IMU. The proposed integrated attitude determination system is tested on practical experimental platform. And experiment results with superior precision and reliability show the feasibility and effectiveness of the proposed attitude determination system.
Valentine, Sean R; Godkin, Jennie; Doughty, Graeme P
There is reason to believe that various cultural attitudes and beliefs influence certain health behaviors, and additional research should identify the causes of such behaviors. This study explored the relationships among cultural identity, acculturation, locus of control, and health beliefs using a sample of 110 Hispanic individuals taking college classes in the southern or southwestern United States. Path analysis indicated that an external locus of control was positively related to health barrier perceptions and that acculturation was negatively related to health barrier perceptions. The findings suggest that Hispanics' perceived control over health outcomes and positive health beliefs could be enhanced with culturally perceptive counseling.
A report discusses the ability to control the attitude and translation degrees-of-freedom of a solar sail vehicle by changing its center of gravity. A movement of the spacecraft s center of mass causes solar-pressure force to apply a torque to the vehicle. At the compact core of the solar-sail vehicle lies the spacecraft bus which is a large fraction of the total vehicle mass. In this concept, the bus is attached to the spacecraft by two single degree-of-freedom linear tracks. This allows relative movement of the bus in the sail plane. At the null position, the resulting solar pressure applies no torque to the vehicle. But any deviation of the bus from the null creates an offset between the spacecraft center of mass and center of solar radiation pressure, resulting in a solar-pressure torque on the vehicle which changes the vehicle attitude. Two of the three vehicle degrees of freedom can be actively controlled in this manner. The third, the roll about the sunline, requires a low-authority vane/propulsive subsystem. Translation control of the vehicle is achieved by directing the solar-pressure-induced force in the proper inertial direction. This requires attitude control. Attitude and translation degrees-of-freedom are therefore coupled. A guidance law is proposed, which allows the vehicle to stationkeep at an appropriate point on the inertially-rotating Sun-Earth line. Power requirements for moving the bus are minimal. Extensive software simulations have been performed to demonstrate the feasibility of this concept.
Xiong, Jing-Jing; Zheng, En-Hui
A synthesis control method is proposed to perform the position and attitude tracking control of the dynamical model of a small quadrotor unmanned aerial vehicle (UAV), where the dynamical model is underactuated, highly-coupled and nonlinear. Firstly, the dynamical model is divided into a fully actuated subsystem and an underactuated subsystem. Secondly, a controller of the fully actuated subsystem is designed through a novel robust terminal sliding mode control (TSMC) algorithm, which is utilized to guarantee all state variables converge to their desired values in short time, the convergence time is so small that the state variables are acted as time invariants in the underactuated subsystem, and, a controller of the underactuated subsystem is designed via sliding mode control (SMC), in addition, the stabilities of the subsystems are demonstrated by Lyapunov theory, respectively. Lastly, in order to demonstrate the robustness of the proposed control method, the aerodynamic forces and moments and air drag taken as external disturbances are taken into account, the obtained simulation results show that the synthesis control method has good performance in terms of position and attitude tracking when faced with external disturbances. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Eiser, J. Richard
This paper considers how conventional theories of attitudes and the self may be reconceptualized from the perspective of chaos theory and work on self-organization. Within attitude theory, there has been a long tradition of research that has treated attitudes as single points on a bipolar evaluative continuum. More recent approaches to attitudes treat attitudes as structures of evaluative associations stored in memory (Fazio, 1990). This work can be linked to chaos theory by regarding attitudes as attractors (Eiser, 1994) within a phase space whose dimensions correspond broadly to features of the attitude object and its context and which is contoured by previous and concurrent associative learning Specifically, it is proposed that attractors are laid down through processes of association. such as may be simulated through connectionist, or parallel distributed processing, systems. Associative learning and memory processes also are implicated in our concept of self, linking with the philosophy of Hume and contemporary research on interactive models of personality (Mischel & Shoda, 1995). Speculatively, it is suggested that consciousness involves representation of the self within a patterned (i.e. self-organized) environment.
Knapp, Roger Glenn
A fuzzy-based attitude controller is designed for attitude control of a generic spacecraft with on/off thrusters. The controller is comprised of packages of rules dedicated to addressing different objectives (e.g., disturbance rejection, low fuel consumption, avoiding the excitation of flexible appendages, etc.). These rule packages can be inserted or removed depending on the requirements of the particular spacecraft and are parameterized based on vehicle parameters such as inertia or operational parameters such as the maneuvering rate. Individual rule packages can be 'weighted' relative to each other to emphasize the importance of one objective relative to another. Finally, the fuzzy controller and rule packages are demonstrated using the high-fidelity Space Shuttle Interactive On-Orbit Simulator (IOS) while performing typical on-orbit operations and are subsequently compared with the existing shuttle flight control system performance.
Full Text Available Abstract Input saturation must be taken into account for applying rapid reorientation in the large angle manoeuvre of a quadrotor. In this paper, a backstepping-based inverse optimal attitude controller (BIOAC is derived which has the property of a maximum convergence rate in the sense of a control Lyapunov function (CLF under input torque limitation. In the controller, a backstepping technique is used for handling the complexity introducing by the unit quaternion representation of the attitude of a quadrotor with four parameters. Moreover, the inverse optimal approach is employed to circumvent the difficulty of solving the Hamilton-Jacobi-Bellman (HJB equation. The performance of BIOAC is compared with a PD controller in which the input torque limitation is not considered under the same unit quaternion representation using numerical simulation while the results show that BIOAC gains faster convergence with less control effort. Next, BIOAC is realized on a test bed and the effectiveness of the control law is verified by experimental studies.
Calvo, Daniel; Laverón-Simavilla, Ana; Lapuerta, Victoria; Aviles, Taisir
Fuzzy logic controllers are flexible and simple, suitable for small satellites Attitude Determination and Control Subsystems (ADCS). In this work, a tailored fuzzy controller is designed for a nanosatellite and is compared with a traditional Proportional Integrative Derivative (PID) controller. Both control methodologies are compared within the same specific mission. The orbit height varies along the mission from injection at around 380 km down to a 200 km height orbit, and the mission requires pointing accuracy over the whole time. Due to both the requirements imposed by such a low orbit, and the limitations in the power available for the attitude control, a robust and efficient ADCS is required. For these reasons a fuzzy logic controller is implemented as the brain of the ADCS and its performance and efficiency are compared to a traditional PID. The fuzzy controller is designed in three separated controllers, each one acting on one of the Euler angles of the satellite in an orbital frame. The fuzzy memberships are constructed taking into account the mission requirements, the physical properties of the satellite and the expected performances. Both methodologies, fuzzy and PID, are fine-tuned using an automated procedure to grant maximum efficiency with fixed performances. Finally both methods are probed in different environments to test their characteristics. The simulations show that the fuzzy controller is much more efficient (up to 65% less power required) in single maneuvers, achieving similar, or even better, precision than the PID. The accuracy and efficiency improvement of the fuzzy controller increase with orbit height because the environmental disturbances decrease, approaching the ideal scenario. A brief mission description is depicted as well as the design process of both ADCS controllers. Finally the validation process and the results obtained during the simulations are described. Those results show that the fuzzy logic methodology is valid for small
Aleksandrov, A. Yu.; Tikhonov, A. A.
A satellite in a circular near-Earth orbit is under consideration. The three-axis stabilization of the satellite in the orbital coordinate system with the use of electrodynamic attitude control system is studied. No constraints are imposed on the Earth's magnetic field approximation. The gravity gradient disturbing torque acting on the satellite attitude dynamics is taken into account as the largest disturbing torque. With the use of the Lyapunov direct method, conditions under which electrodynamic control solves the problem are obtained. The restrictions on the control parameter values for which one can guarantee the asymptotic stability of the programmed satellite motion are found and represented in an explicit form. Comparison of the results of numerical simulation and analytical investigation demonstrate effectiveness of the proposed approach.
Full Text Available A dynamic attitude measurement system (DAMS is developed based on a laser inertial navigation system (LINS. Three factors of the dynamic attitude measurement error using LINS are analyzed: dynamic error, time synchronization and phase lag. An optimal coning errors compensation algorithm is used to reduce coning errors, and two-axis wobbling verification experiments are presented in the paper. The tests indicate that the attitude accuracy is improved 2-fold by the algorithm. In order to decrease coning errors further, the attitude updating frequency is improved from 200 Hz to 2000 Hz. At the same time, a novel finite impulse response (FIR filter with three notches is designed to filter the dither frequency of the ring laser gyro (RLG. The comparison tests suggest that the new filter is five times more effective than the old one. The paper indicates that phase-frequency characteristics of FIR filter and first-order holder of navigation computer constitute the main sources of phase lag in LINS. A formula to calculate the LINS attitude phase lag is introduced in the paper. The expressions of dynamic attitude errors induced by phase lag are derived. The paper proposes a novel synchronization mechanism that is able to simultaneously solve the problems of dynamic test synchronization and phase compensation. A single-axis turntable and a laser interferometer are applied to verify the synchronization mechanism. The experiments results show that the theoretically calculated values of phase lag and attitude error induced by phase lag can both match perfectly with testing data. The block diagram of DAMS and physical photos are presented in the paper. The final experiments demonstrate that the real-time attitude measurement accuracy of DAMS can reach up to 20″ (1σ and the synchronization error is less than 0.2 ms on the condition of three axes wobbling for 10 min.
Roithmayr, Carlos M.; Karlgaard, Christopher D.; Kumar, Renjith R.; Bose, David M.
A law is designed for simultaneous control of the orientation of an Earth-pointing spacecraft, the energy stored by counter-rotating flywheels, and the angular momentum of the flywheels and control moment gyroscopes used together as all integrated set of actuators for attitude control. General. nonlinear equations of motion are presented in vector-dyadic form, and used to obtain approximate expressions which are then linearized in preparation for design of control laws that include feedback of flywheel kinetic energy error as it means of compensating for damping exerted by rotor bearings. Two flywheel 'steering laws' are developed such that torque commanded by all attitude control law is achieved while energy is stored or discharged at the required rate. Using the International Space Station as an example, numerical simulations are performed to demonstrate control about a torque equilibrium attitude and illustrate the benefits of kinetic energy error feedback.
National Aeronautics and Space Administration — A Nitrous Oxide-fed Liquid Thrust Vector Control system is proposed as an efficient method for vehicle attitude control during powered flight. Pulled from a N2O main...
A self-constructed questionnaire titled “Librarians Attitudes to Computerised Information Systems (LACIS)” was administered to evaluate the perception of Librarians at the Kenneth Dike Library, University of Ibadan on the use of computerised information system. Based on a four-point Lickert scale, descriptive and inferential ...
Mason, James Paul; Baumgart, Matt; Rogler, Bryan; Downs, Chloe; Williams, Margaret; Woods, Thomas N.; Palo, Scott; Chamberlin, Phillip C.; Solomon, Stanley; Jones, Andrew; Li, Xinlin; Kohnert, Rick; Caspi, Amir
The Miniature X-ray Solar Spectrometer (MinXSS) is a three-unit (3U) CubeSat designed for a three-month mission to study solar soft X-ray spectral irradiance. The first of the two flight models was deployed from the International Space Station in May 2016, and operated for one year before its natural deorbiting. This was the first flight of the Blue Canyon Technologies XACT 3-axis attitude determination and control system - a commercially available, high-precision pointing system. The performance of the pointing system on orbit was characterized, including performance at low altitudes where drag torque builds up. It was found that the pointing accuracy was 0.0042° - 0.0117° (15" - 42", 3σ, axis dependent) consistently from 190 km - 410 km, slightly better than the specification sheet states. Peak-to-peak jitter was estimated to be 0.0073° (10 s^-1) - 0.0183° (10 s^-1) (26" (10 s^-1) - 66" (10 s^-1), 3σ). The system was capable of dumping mome ntum until an altitude of 185 km. Small amounts of sensor degradation were found in the star tracker and coarse sun sensor. The mission profile did not require high-agility maneuvers, so it was not possible to characterize this metric. Without a GPS receiver, it was necessary to periodically upload ephemeris information to update the orbit propagation model and maintain pointing. At 400 km, these uploads were required once every other week; at ˜270 km, they were required every day. The power performance of the electric power system was also characterized, including use of a novel pseudo-peak power tracker - a resistor that limited the current draw from the battery on the solar panels. With 19 30% efficient solar cells and an 8 W system load, the power balance had 65% of margin on orbit. The current paper presents several recommendations to other CubeSat programs throughout.
Full Text Available Purpose: Operation of attitude and heading reference systems in conditions of autonomy and high accuracy requires usage of gimballed platforms. The goal of the paper is detailed research of such systems kinematics and control moments. As result the full mathematical model of the precision attitude and heading reference system with the biaxial horizontal platform was derived. Methods: Obtaining of the mathematical model is based on the theory of gyros in general and corrected gyro compasses and theory of dynamically tuned gyros in particular. The basic laws of theoretical mechanics including concepts of Euler angles and directional cosines were taken into consideration. Results: The full mathematical model of the attitude and heading reference system is developed. The mathematical models of the vertical gyro and directional gyro as components of the researched system are given. The simulation results based on the developed models are presented. Conclusions: The mathematical model of the gimballed attitude and heading reference system including the vertical gyro and directional gyro is derived. The detailed expressions for control (correction moments are obtained. The full analysis of the researched system kinematics was carried out. The obtained results can also be useful for design of inertial navigation systems of the wide class.
Baculi, Joshua; Ayoubi, Mohammad A.
This study presents a fuzzy tracking controller based on the Takagi-Sugeno (T-S) fuzzy model of the solar sail. First, the T-S fuzzy model is constructed by linearizing the existing nonlinear equations of motion of the solar sail. Then, the T-S fuzzy model is used to derive the state feedback controller gains for the Twin Parallel Distributed Compensation (TPDC) technique. The TPDC tracks and stabilizes the attitude of the solar sail to any desired state in the presence of parameter uncertainties and external disturbances while satisfying actuator constraints. The performance of the TPDC is compared to a PID controller that is tuned using the Ziegler-Nichols method. Numerical simulation shows the TPDC outperforms the PID controller when stabilizing the solar sail to a desired state.
Lu, Yingbo; Huang, Panfeng; Meng, Zhongjie; Hu, Yongxin; Zhang, Fan; Zhang, Yizhai
Up to April 6, 2016, there are 17,385 large debris in orbit around the Earth, which poses a serious hazard to near-Earth space activities. As a promising on-orbit debris capture strategy, tethered space robots (TSRs) have wide applications in future on-orbit service owing to its flexibility and great workspace. However, lots of problems may arise in the Tethered Space Robots (TSRs) system from the approaching, capturing, postcapturing and towing phases. The postcapture combination attitude takeover control by the TSR is studied in this paper. Taking control constraints, tether oscillations and external disturbances into consideration, a fast terminal sliding mode control (FTSMC) methodology with dual closed loops for the flexible combination attitude takeover control is designed. The unknown upper bounds of the uncertainties, external disturbances are estimated through adaptive techniques. Stability of the dual closed loop control system and finite time convergence of system states are proved via Lyapunov stability theory. Besides, null space intersection control allocation was adopted to distribute the required control moment over TSR's redundant thrusters. Simulation studies have been conducted to demonstrate the effectiveness of the proposed controller with the conventional sliding mode control(SMC).
de Barcellos, Marcia Dutra; Kügler, Jens Oliver; Saab, Maria Stella Melo
to identify Brazilian citizen clusters. Respondents' socio-demographic profile, attitudes towards issues that are expected to influence the way how people evaluate pig meat production systems, and consumption frequency of various pork products were used as background information for profiling. Three clusters......The objective of this study is to map Brazilian citizen attitudes towards pig meat production systems and to investigate whether these attitudes associate with pork and pork product consumption. A conjoint experiment was carried out with empirical data collected from 475 respondents interviewed...... and consumption behaviour was found to be weak. As it was suggested for Europe (Krystallis et al., 2009), what people think in their role as citizens related to pig production does not appear to significantly influence their pork consumption choices....
Wilson, David G [Tijeras, NM; Robinett, III, Rush D.
A control system design method and concomitant control system comprising representing a physical apparatus to be controlled as a Hamiltonian system, determining elements of the Hamiltonian system representation which are power generators, power dissipators, and power storage devices, analyzing stability and performance of the Hamiltonian system based on the results of the determining step and determining necessary and sufficient conditions for stability of the Hamiltonian system, creating a stable control system based on the results of the analyzing step, and employing the resulting control system to control the physical apparatus.
Bhugra, D; King, M
A controlled analysis of the attitudes of doctors and homosexual men to male homosexuality is reported. Not surprisingly the homosexual men held the most liberal attitudes which served as a yard-stick against which the doctors' attitudes could be assessed. The implications of these data, collected before the AIDS era, are discussed in terms of the current needs of homosexual patients. PMID:2810298
Mirshams, M.; Khosrojerdi, M.
Feasibility of achieving 3-axis stabilization of an asymmetric spacecraft for cases where there is no control available in one axis (underactuated spacecraft) is explored in this paper. A novel control design methodology is presented which can stabilize the underactuated spacecraft and steer it to the origin. A passive fault tolerant control (FTC) is defined which controls and maintains the attitude of the spacecraft near the desired point in presence of uncertainties, disturbances, control constraints and actuator faults. Considering the general conditions of the underactuated spacecraft, a hybrid controller combining a quaternion feedback regulator (QFR) with a tube-based model predictive controller (MPC) is developed based on the nonlinear kinematic and dynamic equations of the spacecraft motion. The hybrid controller is composed of two control stages. At the first stage, QFR decreases the angular velocities and brings the state vector to an acceptable region for the next stage. Then, tube-based MPC solves two optimal control problems, a standard problem for the nominal system to define a central guide path, and an ancillary problem to steer the state vector towards the central path with semi-optimal control effort. Numerical simulation results obtained for the underactuated spacecraft merely indicate effectiveness of the proposed attitude control method.
Guerrant, Daniel Vernon
Solar sails enable or enhance exploration of a variety of destinations both within and without the solar system. The heliogyro solar sail architecture divides the sail into blades spun about a central hub and centrifugally stiffened. The resulting structural mass savings can often double acceleration verses kite-type square sails of the same mass. Pitching the blades collectively and cyclically, similar to a helicopter, creates attitude control moments and vectors thrust. The principal hurdle preventing heliogyros' implementation is the uncertainty in their dynamics. This thesis investigates attitude, orbital and structural control using a combination of analytical studies and simulations. Furthermore, it quantifies the heliogyro's ability to create attitude control moments, change the thrust direction, and stably actuate blade pitch. This provides engineers a toolbox from which to estimate the heliogyro's performance and perform trades during preliminary mission design. It is shown that heliogyros can create an attitude control moment in any direction from any orientation. While their large angular momentum limits attitude slewing to only a few degrees per hour, cyclic blade pitching can slew the thrust vector within a few minutes. This approach is only 13% less efficient than slewing a square sail during Earth escape, so it does not offset the overall acceleration benefits of heliogyros. Lastly, a root pitch motor should be able to settle torsional disturbances within a few rotations and achieve thrust performance comparable to that of flat blades. This work found no significant dynamic hurdles for heliogyros, and it provides key insight into their practical capabilities and limitations for future mission designers.
ISAAC E. ILEVBAOJE. ABSTRACT. This study was undertaken to ﬁnd out the attitudes of extension workers to the training and visit (T&V) extension system as a complimentary step to specify if this extension approach is on course in Nigeria. Results obtained indicate that about 10. 8, 65.8 and 23.3% of the extension ...
Liechty, Janet M; Saltzman, Jaclyn A; Musaad, Salma M
The purpose of this study was to examine associations between parental health literacy and parent attitudes about weight control strategies for young children. Parental low health literacy has been associated with poor child health outcomes, yet little is known about its relationship to child weight control and weight-related health information-seeking preferences. Data were drawn from the STRONG Kids Study, a Midwest panel survey among parents of preschool aged children (n = 497). Parents endorsed an average of 4.3 (SD =2.8) weight loss strategies, 53% endorsed all three recommended weight loss strategies for children, and fewer than 1% of parents endorsed any unsafe strategies. Parents were most likely to seek child weight loss information from healthcare professionals but those with low (vs. adequate) health literacy were significantly less likely to use the Internet or books and more likely to use minister/clergy as sources. Poisson and logistic regressions showed that higher health literacy was associated with endorsement of more strategies overall, more recommended strategies, and greater odds of endorsing each specific recommended strategy for child weight control, after adjusting for parent age, education, race/ethnicity, income, marital status, weight concern, and child BMI percentile. Findings suggest that health literacy impacts parental views about child weight loss strategies and health information-seeking preferences. Pediatric weight loss advice to parents should include assessment of parent attitudes and prior knowledge about child weight control and facilitate parent access to reliable sources of evidence-informed child weight control information. Copyright © 2015 Elsevier Ltd. All rights reserved.
Hendrick; Jheng, Jyun-Teng; Tsai, Chen-Chai; Liou, Jia-Wei; Wang, Zhi-Hao; Jong, Gwo-Jia
Intelligent appliances wisdom involves security, home care, convenient and energy saving, but the home automation system is still one of the core unit, and also using micro-processing electronics technology to centralized and control the home electrical products and systems, such as: lighting, television, fan, air conditioning, stereo, it composed of front-controller systems and back-controller panels, user using front-controller to control command, and then through the back-controller to powered the device.
DINC, M. Sait; BUDIC, Semira
.... The purpose of the study is to examine the relationship between demographic variables, personal attitude, subjective norm, perceived behavioural control, and entrepreneurial intentions of women...
Forcey, W.; Minnie, C. R.; Defazio, R. L.
The Geostationary Operational Environmental Satellite (GOES)-8 experienced a series of orbital perturbations from autonomous attitude control thrusting before perigee raising maneuvers. These perturbations influenced differential correction orbital state solutions determined by the Goddard Space Flight Center (GSFC) Goddard Trajectory Determination System (GTDS). The maneuvers induced significant variations in the converged state vector for solutions using increasingly longer tracking data spans. These solutions were used for planning perigee maneuvers as well as initial estimates for orbit solutions used to evaluate the effectiveness of the perigee raising maneuvers. This paper discusses models for the incorporation of attitude thrust effects into the orbit determination process. Results from definitive attitude solutions are modeled as impulsive thrusts in orbit determination solutions created for GOES-8 mission support. Due to the attitude orientation of GOES-8, analysis results are presented that attempt to absorb the effects of attitude thrusting by including a solution for the coefficient of reflectivity, C(R). Models to represent the attitude maneuvers are tested against orbit determination solutions generated during real-time support of the GOES-8 mission. The modeling techniques discussed in this investigation offer benefits to the remaining missions in the GOES NEXT series. Similar missions with large autonomous attitude control thrusting, such as the Solar and Heliospheric Observatory (SOHO) spacecraft and the INTELSAT series, may also benefit from these results.
Motion Coordination for VTOL Unmanned Aerial Vehicles develops new control design techniques for the distributed coordination of a team of autonomous unmanned aerial vehicles. In particular, it provides new control design approaches for the attitude synchronization of a formation of rigid body systems. In addition, by integrating new control design techniques with some concepts from nonlinear control theory and multi-agent systems, it presents a new theoretical framework for the formation control of a class of under-actuated aerial vehicles capable of vertical take-off and landing. Several practical problems related to the systems’ inputs, states measurements, and restrictions on the interconnection topology between the aerial vehicles in the team are addressed. Worked examples with sufficient details and simulation results are provided to illustrate the applicability and effectiveness of the theoretical results discussed in the book. The material presented is primarily intended for researchers an...
Wu, Anise M S; Lai, Mark H C; Tong, Kowk Kit; Tao, Vivienne Y K
This study tested the applicability of the theory of planned behavior (TPB) on gambling intention and involvement in a representative Chinese sample in Macao, recruited by a random residential number dialing method. We successfully interviewed 685 respondents, with about one-third of them reporting that they had participated in gambling activities during the 12 months prior to the interview. The results of structural equation modeling suggested that favorable attitudes toward superstition and techniques, poor sense of perceived behavioral control over gambling refusal, and high gambling intention increased vulnerability to excessive gambling involvement. These findings generally support the efficacy of the TPB in explaining gambling intention and involvement among both Chinese gamblers and non-gamblers. Some practical implications of the findings are discussed within the Chinese context.
Wu, Yunhua; Han, Feng; Zheng, Mohong; He, Mengjie; Chen, Zhiming; Hua, Bing; Wang, Feng
On-orbit servicing is one of the research hotspots of space missions. A small satellite equipped with multiple robotic manipulators is expected to carry out device replacement task for target large spacecraft. Attitude hyperstable control of a small satellite platform under rotations of the manipulators is a challenging problem. A hybrid momentum exchanging actuator consists of Control Moment Gyro (CMG) and Reaction Wheel (RW) is proposed to tackle the above issue, due to its huge amount of momentum storage capacity of the CMG and high control accuracy of the RW, in which the CMG produces large command torque while the RW offers additional control degrees. The constructed dynamic model of the servicing satellite advises that it's feasible for attitude hyperstable control of the platform with arbitrary manipulators through compensating the disturbance generated by rapid rotation of the manipulators. Then, null motion between the CMG and RW is exploited to drive the system to the expected target with favorable performance, and to overcome the CMG inherent geometric singularity and RW saturation. Simulations with different initial situations, including CMG hyperbolic and elliptic singularities and RW saturation, are executed. Compared to the scenarios where the CMG or RW fails stabilizing the platform, large control torque, precise control effect and escape of singularity are guaranteed by the introduced hybrid actuator, CMGRW (CMGRW refers to the hybrid momentum exchanging devices in this paper, consisting of 4 CMGs in classical pyramid cluster and 3 RWs in an orthogonal group (specific description can been found in Section 4)). The feasible performance of the satellite, CMG and RW under large disturbance demonstrates that the control architecture proposed is capable of attitude control for on-orbit servicing satellite with multiple robotic manipulators.
Dresler, Carolyn; Wei, Mei; Heck, Julia E; Allwright, Shane; Haglund, Margaretha; Sanchez, Sara; Kralikova, Eva; Stücker, Isabelle; Tamang, Elizabeth; Gritz, Ellen R; Hashibe, Mia
Tobacco-related cancers and, in particular, lung cancer still represents a substantial public health epidemic across Europe as a result of high rates of smoking prevalence. Countries in Europe have proposed and implemented tobacco control policies to reduce smoking prevalence, with some countries being more progressive than others. The aim of this study was to examine factors that influenced women's attitudes across five European countries relative to comprehensive smokefree laws in their countries. A cross-sectional landline telephone survey on attitudes towards tobacco control laws was conducted in five European countries: France, Ireland, Italy, the Czech Republic, and Sweden. Attitudinal scores were determined for each respondent relative to questions about smokefree laws. Logistic regression models were used to obtain odds ratios with 95% confidence intervals. A total of 5000 women were interviewed (1000 women from each country). The majority of women, regardless of smoking history, objected to smoking in public buses, enclosed shopping centers, hospitals, and other indoor work places. More women who had quit smoking believed that new tobacco control laws would prompt cessation - as compared with women who still smoked. In general, there is very high support for national smokefree laws that cover bars, restaurants, and public transport systems. As such laws are implemented, attitudes do change, as demonstrated by the differences between countries such as Ireland and the Czech Republic. Implementing comprehensive smokefree laws will gain high approval and will be associated with prompting people to quit.
An alternative propulsion subsystem for MSAT is presented which has a potential of reducing the satellite weight by more than 15%. The characteristics of pulsed plasma and ion engines are described and used to estimate of the mass of the propellant and thrusters for attitude control and stationkeeping functions for MSAT. Preliminary estimates indicate that the electric propulsion systems could also replace the large momentum wheels necessary to counteract the solar pressure; however, the fine pointing wheels would be retained. Estimates also show that either electric propulsion system can save approximately 18% to 20% of the initial 4,000 kg mass. The issues that require further experimentation are mentioned.
Lin, Ching Fang
A special navigation system is being developed to provide high-quality information on the position and attitude of a moving platform (an aircraft or spacecraft), for use in pointing and stabilization of a hyperspectral remote-sensing system carried aboard the platform. The system also serves to enable synchronization and interpretation of readouts of all onboard sensors. The heart of the system is a commercially available unit, small enough to be held in one hand, that contains an integral combination of an inertial measurement unit (IMU) of the microelectromechanical systems (MEMS) type, Global Positioning System (GPS) receivers, a differential GPS subsystem, and ancillary data-processing subsystems. The system utilizes GPS carrier-phase measurements to generate time data plus highly accurate and continuous data on the position, attitude, rotation, and acceleration of the platform. Relative to prior navigation systems based on IMU and GPS subsystems, this system is smaller, is less expensive, and performs better. Optionally, the system can easily be connected to a laptop computer for demonstration and evaluation. In addition to airborne and spaceborne remote-sensing applications, there are numerous potential terrestrial sensing, measurement, and navigation applications in diverse endeavors that include forestry, environmental monitoring, agriculture, mining, and robotics.
, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusses linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field...... systems is limited, nevertheless, a solution of the Riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when a satellite is on a near polar orbit is used throughout this paper. Three types of attitude......Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvement of micro-electronics. Required pointing accuracy of small, inexpensive satellites is often relatively loose, within a couple of degrees. Application of cheap...
Da Fonseca, Ijar M.; Goes, Luiz C. S.; Seito, Narumi; da Silva Duarte, Mayara K.; de Oliveira, Élcio Jeronimo
In space the manipulators working space is characterized by the microgravity environment. In this environment the spacecraft floats and its rotational/translational motion may be excited by any internal and external disturbances. The complete system, i.e., the spacecraft and the associated robotic manipulator, floats and is sensitive to any reaction force and torque related to the manipulator's operation. In this sense the effort done by the robot may result in torque about the system center of mass and also in forces changing its translational motion. This paper analyzes the impact of the robot manipulator dynamics on the attitude motion and the associated control effort to keep the attitude stable during the manipulator's operation. The dynamics analysis is performed in the close proximity phase of rendezvous docking/berthing operation. In such scenario the linear system equations for the translation and attitude relative motions are appropriate. The computer simulations are implemented for the relative translational and rotational motion. The equations of motion have been simulated through computer by using the MatLab software. The LQR and the PID control laws are used for linear and nonlinear control, respectively, aiming to keep the attitude stable while the robot is in and out of service. The gravity-gradient and the residual magnetic torque are considered as external disturbances. The control efforts are analyzed for the manipulator in and out of service. The control laws allow the system stabilization and good performance when the manipulator is in service.
Nurul Dayana Salim
Full Text Available This paper proposes a robust optimal attitude control design for multiple-input, multiple-output (MIMO uncertain hexarotor micro aerial vehicles (MAVs in the presence of parametric uncertainties, external time-varying disturbances, nonlinear dynamics, and coupling. The parametric uncertainties, external time-varying disturbances, nonlinear dynamics, and coupling are treated as the total disturbance in the proposed design. The proposed controller is achieved in two simple steps. First, an optimal linear-quadratic regulator (LQR controller is designed to guarantee that the nominal closed-loop system is asymptotically stable without considering the total disturbance. After that, a disturbance observer is integrated into the closed-loop system to estimate the total disturbance acting on the system. The total disturbance is compensated by a compensation input based on the estimated total disturbance. Robust properties analysis is given to prove that the state is ultimately bounded in specified boundaries. Simulation results illustrate the robustness of the disturbance observer-based optimal attitude control design for hovering and aggressive flight missions in the presence of the total disturbance.
however, there are many dual-use applications, such as regenerative braking technology and flywheel energy storage. The reaction wheel system on Simsat...wheel and thruster control systems . The control moment gyroscope array was required to interface with SimSat’s existing structure, power supply, and...Captain Ryan Snider for sharing his lessons about Simsat, practical knowledge, and valuable hands-on time with someone who knew the system . Next, I’d
Wisniewski, Rafal; Stoustrup, Jakob
the expected magnetic field vector and the true magnetometer data is used for the attitude determination. The magnetic attitude control and determination is intrinsically periodic due to periodic nature of the geomagnetic field variation in orbit. The control performance is specified by the generalized H2...
Oleiro Seabra, Luis Filipe; The ATLAS collaboration
ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS/LHC. The ALFA system is composed by two stations installed in the LHC tunnel 240 m away from each side of the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronic for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.
Oleiro Seabra, Luis Filipe; The ATLAS collaboration
ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.
Posokhova, Svetlana; Konovalova, Natalia; Sorokin, Victor; Demyanov, Yuri; Kolosova, Tatyana; Didenko, Elena
The objective of the research was to identify the system of attitudes in parents of young people having sensory disorders. The survey covered parents of children aged 17 and older having hearing disorders, visual disorders, and no sensory disorders. The parents' system of attitudes united the attitude of the parents to themselves, to the child and…
Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar
The output of the attitude determination systems suffers from large errors in case of accelerometer malfunctions. In this paper, an attitude estimator, based on Virtual Horizontal Reference (VHR), is designed for an Attitude Heading and Reference System (AHRS) to cope with this problem. The VHR m...
Peyran, Richard J.; Laub, Georgene H.; Morse, H. Andrew
A mechanical system to control the position of a rotating swashplate is developed. This system provides independent lateral cyclic, longitudinal cyclic and collective pitch control of a helicopter rotor attached to the swashplate, without use of a mixer box. The system also provide direct, linear readout of cyclic and collective swashplate positions.
for attitude control of a satellite in space begin with Euler’s equation ~Mb̂ = Ib̂ ~̇ω b̂î b̂ + ~ωb̂î b̂ × Ib̂~ωb̂îb̂ (2.1) where ~Mb̂ is a vector...calculation is given in Section 2.5. The final set of equations needed to study satellite attitude control is a set of kinematic relations...greater than 0.025% over the whole mission. Due to the nonlinear equations involved in satellite control, the ~̇hmax value is further checked and
"Presents a unified approach to the fundamental issues in motion control, starting from the basics and moving through single degree of freedom and multi-degree of freedom systems In Motion Control Systems, Šabanovic and Ohnishi present a unified approach to very diverse issues covered in motion control systems, offering know-how accumulated through work on very diverse problems into a comprehensive, integrated approach suitable for application in high demanding high-tech products. It covers material from single degree of freedom systems to complex multi-body non-redundant and redundant systems. The discussion of the main subject is based on original research results and will give treatment of the issues in motion control in the framework of the acceleration control method with disturbance rejection technique. This allows consistent unification of different issues in motion control ranging from simple trajectory tracking to topics related to haptics and bilateral control without and with delay in the measure...
Mahmoud, Magdi S
Applied Control System Design examines several methods for building up systems models based on real experimental data from typical industrial processes and incorporating system identification techniques. The text takes a comparative approach to the models derived in this way judging their suitability for use in different systems and under different operational circumstances. A broad spectrum of control methods including various forms of filtering, feedback and feedforward control is applied to the models and the guidelines derived from the closed-loop responses are then composed into a concrete self-tested recipe to serve as a check-list for industrial engineers or control designers. System identification and control design are given equal weight in model derivation and testing to reflect their equality of importance in the proper design and optimization of high-performance control systems. Readers’ assimilation of the material discussed is assisted by the provision of problems and examples. Most of these e...
Full Text Available In this paper, an adaptive attitude control algorithm is developed based on neural network for a satellite using four reaction wheels in a tetrahedron configuration. Then, an attitude control based on feedback linearization control has been designed and uncertainties in the moment of inertia matrix and disturbances torque have been considered. In order to eliminate the effect of these uncertainties, a multilayer neural network with back-propagation law is designed. In this structure, the parameters of the moment of inertia matrix and external disturbances are estimated and used in feedback linearization control law. Finally, the performance of the designed attitude controller is investigated by several simulations.
A system for optimizing a power plant includes a chemical loop having an input for receiving an input parameter (270) and an output for outputting an output parameter (280), a control system operably connected to the chemical loop and having a multiple controller part (230) comprising a model-free controller. The control system receives the output parameter (280), optimizes the input parameter (270) based on the received output parameter (280), and outputs an optimized input parameter (270) to the input of the chemical loop to control a process of the chemical loop in an optimized manner.
Nise, Norman S
This completely updated new edition shows how to use MATLAB to perform control-system calculations. Designed for the professional or engineering student who needs a quick and readable update on designing control systems, the text features a series of tightly focused examples that clearly illustrate each concept of designing control systems. Most chapters conclude with a detailed application from the two case studies that run throughout the book: an antenna asimuth control system and a submarine. The author also refers to many examples of design methods.
Pirmoradi, F. N.; Sassani, F.; de Silva, C. W.
This paper presents a new scheme for fault detection and diagnosis (FDD) in spacecraft attitude determination (AD) sensors. An integrated attitude determination system, which includes measurements of rate and angular position using rate gyros and vector sensors, is developed. Measurement data from all sensors are fused by a linearized Kalman filter, which is designed based on the system kinematics, to provide attitude estimation and the values of the gyro bias. Using this information the erroneous sensor measurements are corrected, and unbounded sensor measurement errors are avoided. The resulting bias-free data are used in the FDD scheme. The FDD algorithm uses model-based state estimation, combining the information from the rotational dynamics and kinematics of a spacecraft with the sensor measurements to predict the future sensor outputs. Fault isolation is performed through extended Kalman filters (EKFs). The innovation sequences of EKFs are monitored by several statistical tests to detect the presence of a failure and to localize the failures in all AD sensors. The isolation procedure is developed in two phases. In the first phase, two EKFs are designed, which use subsets of measurements to provide state estimates and form residuals, which are used to verify the source of the fault. In the second phase of isolation, testing of multiple hypotheses is performed. The generalized likelihood ratio test is utilized to identify the faulty components. In the scheme developed in this paper a relatively small number of hypotheses is used, which results in faster isolation and highly distinguishable fault signatures. An important feature of the developed FDD scheme is that it can provide attitude estimations even if only one type of sensors is functioning properly.
Gao, Yuan; Feng, Yuchao; Wang, Min; Su, Yiwei; Li, Yanhua; Wang, Zhi; Tang, Shihao
To develop the knowledge, attitude and practice questionnaire on the prevention and control of occupational diseases for occupational groups, and to provide a convenient and effective tool for the survey of knowledge, attitude, and behavior on the prevention and control of occupational diseases in occupational groups and the evaluation of intervention effect. The initial questionnaire which was evaluated by the experts was used to carry out a pre-survey in Guangzhou, China. The survey results were statistically analyzed by t test, identification index method, correlation analysis, and Cronbach's a coefficient method. And then the questionnaire was further modified, and the content of the questionnaire was determined finally. After modification, there were 18 items on knowledge, 16 items on attitude, and 12 items on behavior in the "Knowledge, attitude and practice questionnaire on the prevention and control of occupational diseases for enterprise managers"; there were 19 items on knowledge, 10 items on attitude, and 11 items on behavior in the "Knowledge, attitude and practice questionnaire on the prevention and control of occupational diseases for workers". The knowledge, attitude and practice questionnaire on the prevention and control of occupational diseases for occupational groups is developed successfully, and it is a convenient and effective tool for the survey of knowledge, attitude, and behavior on the prevention and control of occupational diseases in occupational groups and the evaluation of intervention effect.
failures. It is often feasible to increase availability for these control loops by designing the control system to perform on-line detection and reconfiguration in case of faults before the safety system makes a close-down of the process. A general development methodology is given in the thesis......This thesis considered the development of fault tolerant control systems. The focus was on the category of automated processes that do not necessarily comprise a high number of identical sensors and actuators to maintain safe operation, but still have a potential for improving immunity to component...... that carried the control system designer through the steps necessary to consider fault handling in an early design phase. It was shown how an existing control loop with interface to the plant wide control system could be extended with three additional modules to obtain fault tolerance: Fault detection...
Discrete Control Systems establishes a basis for the analysis and design of discretized/quantized control systemsfor continuous physical systems. Beginning with the necessary mathematical foundations and system-model descriptions, the text moves on to derive a robust stability condition. To keep a practical perspective on the uncertain physical systems considered, most of the methods treated are carried out in the frequency domain. As part of the design procedure, modified Nyquist–Hall and Nichols diagrams are presented and discretized proportional–integral–derivative control schemes are reconsidered. Schemes for model-reference feedback and discrete-type observers are proposed. Although single-loop feedback systems form the core of the text, some consideration is given to multiple loops and nonlinearities. The robust control performance and stability of interval systems (with multiple uncertainties) are outlined. Finally, the monograph describes the relationship between feedback-control and discrete ev...
Sellers, David; Friedman, Hannah; Haasl, Tudi; Bourassa, Norman; Piette, Mary Ann
The ''Control System Design Guide'' (Design Guide) provides methods and recommendations for the control system design process and control point selection and installation. Control systems are often the most problematic system in a building. A good design process that takes into account maintenance, operation, and commissioning can lead to a smoothly operating and efficient building. To this end, the Design Guide provides a toolbox of templates for improving control system design and specification. HVAC designers are the primary audience for the Design Guide. The control design process it presents will help produce well-designed control systems that achieve efficient and robust operation. The spreadsheet examples for control valve schedules, damper schedules, and points lists can streamline the use of the control system design concepts set forth in the Design Guide by providing convenient starting points from which designers can build. Although each reader brings their own unique questions to the text, the Design Guide contains information that designers, commissioning providers, operators, and owners will find useful.
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 5. Systems and Control Engineering - Control Systems-Analysis and Design. A Rama Kalyan J R Vengateswaran. General Article Volume 4 Issue 5 May 1999 pp 88-94 ...
Zhu, Linyu; Guo, Jian; Gill, Eberhard
With respect to spacecraft attitude control, reaction spheres are promising alternatives to conventional momentum exchange devices for the benefits brought by their 4π rotation. Many design concepts of reaction spheres have been proposed in the past decades, however, developments of the driving unit and the bearing, as well as their combination remain great challenges. To facilitate research and push developments in this field, this paper provides a comprehensive review of reaction spheres. To some extent, an in-depth survey of multi-DOF (degree of freedom) spherical motors and possible bearings is provided, along with their advantages and weaknesses addressed. Some multi-DOF actuators for different applications, such as robotic joints, are investigated since they share many similar challenges and techniques with reaction spheres. The experimental performances of realized reaction spheres are listed and compared. Limits of current designs are identified and their causes are analyzed and discussed. Compared with existing summaries on multi-DOF actuators and some surveys done for specific reaction spheres' design, this paper provides the first thorough review on reaction spheres, considering approaches to excite and support the free 4π rotation.
With a rapid increase in the interest in use of nanosatellites in the past decade, finding a precise and low-power-consuming attitude control system for these satellites has been a real challenge. In this thesis, it is intended to design and test an electrospray thruster system that could perform the attitude control of a 1-unit CubeSat. Firstly, an experimental setup is built to calculate the conductivity of different liquids that could be used as propellants for the CubeSat. Secondly, a Time-Of-Flight experiment is performed to find out the thrust and specific impulse given by these liquids and hence selecting the optimum propellant. On the other hand, a colloidal thruster system for a 1-U CubeSat is designed in Solidworks and fabricated using Lathe and CNC Milling Machine. Afterwards, passive propellant feeding is tested in this thruster system. Finally, the electronic circuit and wireless control system necessary to remotely control the CubeSat is designed and the final testing is performed. Among the propellants studied, Ethyl ammonium nitrate (EAN) was selected as the best propellant for the CubeSat. Theoretical design and fabrication of the thruster system was performed successfully and so was the passive propellant feeding test. The satellite was assembled for the final experiment but unfortunately the microcontroller broke down during the first test and no promising results were found out. However, after proving that one thruster works with passive feeding, it could be said that the ACS testing would have worked if we had performed vacuum compatibility tests for other components beforehand.
Full Text Available The hybrid vehicle control system includes a start–stop system for an internal combustion engine. The system works in a hybrid mode and normal vehicle operation. To simplify the start–stop system, there were user new possibilities of a hybrid car, which appeared after the conversion. Results of the circuit design of the proposed system of basic blocks are analyzed.
Drones, subscale vehicles like the Firebees, and full scale retired military aircraft are used to test air defense missile systems. The DFCS (Drone Formation Control System) computer, developed by IBM (International Business Machines) Federal Systems Division, can track ten drones at once. A program called ORACLS is used to generate software to track and control Drones. It was originally developed by Langley and supplied by COSMIC (Computer Software Management and Information Center). The program saved the company both time and money.
Oudekerk, Barbara A.; Allen, Joseph P.; Hafen, Christopher A.; Hessel, Elenda T.; Szwedo, David E.; Spilker, Ann
Maternal and paternal psychological control, peer attitudes, and the interaction of psychological control and peer attitudes at age 13 were examined as predictors of risky sexual behavior before age 16 in a community sample of 181 youth followed from age 13 to 16. Maternal psychological control moderated the link between peer attitudes and sexual…
The Control Systems Security Program and other programs within the Idaho National Laboratory have discovered a vulnerability common to control systems in all sectors that allows an attacker to penetrate most control systems, spoof the operator, and gain full control of targeted system elements. This vulnerability has been identified on several systems that have been evaluated at INL, and in each case a 100% success rate of completing the attack paths that lead to full system compromise was observed. Since these systems are employed in multiple critical infrastructure sectors, this vulnerability is deemed common to control systems in all sectors. Modern control systems architectures can be considered analogous to today's information networks, and as such are usually approached by attackers using a common attack methodology to penetrate deeper and deeper into the network. This approach often is composed of several phases, including gaining access to the control network, reconnaissance, profiling of vulnerabilities, launching attacks, escalating privilege, maintaining access, and obscuring or removing information that indicates that an intruder was on the system. With irrefutable proof that an external attack can lead to a compromise of a computing resource on the organization's business local area network (LAN), access to the control network is usually considered the first phase in the attack plan. Once the attacker gains access to the control network through direct connections and/or the business LAN, the second phase of reconnaissance begins with traffic analysis within the control domain. Thus, the communications between the workstations and the field device controllers can be monitored and evaluated, allowing an attacker to capture, analyze, and evaluate the commands sent among the control equipment. Through manipulation of the communication protocols of control systems (a process generally referred to as ''reverse engineering''), an
Song, Jun Beom [Dept. of Aviation Maintenance, Dongwon Institute of Science and Technology, Yangsan (Korea, Republic of); Byun, Young Seop; Jeong, Jin Seok; Kim, Jeong; Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of)
This paper proposes a cascaded control structure and a method of practical application for attitude control of a multi-rotor Unmanned aerial vehicle (UAV). The cascade control, which has tighter control capability than a single-loop control, is rarely used in attitude control of a multi-rotor UAV due to the input-output relation, which is no longer simply a set-point to Euler angle response transfer function of a single-loop PID control, but there are multiply measured signals and interactive control loops that increase the complexity of evaluation in conventional way of design. However, it is proposed in this research a method that can optimize a cascade control with a primary and secondary loops and a PID controller for each loop. An investigation of currently available PID-tuning methods lead to selection of the Simple internal model control (SIMC) method, which is based on the Internal model control (IMC) and direct-synthesis method. Through the analysis and experiments, this research proposes a systematic procedure to implement a cascaded attitude controller, which includes the flight test, system identification and SIMC-based PID-tuning. The proposed method was validated successfully from multiple applications where the application to roll axis lead to a PID-PID cascade control, but the application to yaw axis lead to that of PID-PI.
Full Text Available The attitude tracking problem of spacecraft in the presence of unknown disturbance is investigated. By using the adaptive control technique and the Lyapunov stability theory, a chattering-free adaptive sliding mode control law is proposed for the attitude tracking problem of spacecraft with unknown disturbance. Simulation results are employed to demonstrate the effectiveness of the proposed control design technique in this paper.
Caglayan, A. K.; Vanlandingham, H. F.
The design of stable feedback control laws for sampled-data systems with variable rate sampling was investigated. These types of sampled-data systems arise naturally in digital flight control systems which use digital actuators where it is desirable to decrease the number of control computer output commands in order to save wear and tear of the associated equipment. The design of aircraft control systems which are optimally tolerant of sensor and actuator failures was also studied. Detection of the failed sensor or actuator must be resolved and if the estimate of the state is used in the control law, then it is also desirable to have an estimator which will give the optimal state estimate even under the failed conditions.
Trudnowski, Daniel [Montana Tech of the Univ. of Montana, Butte, MT (United States)
This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”
Carvalho, Ivo S., E-mail: firstname.lastname@example.org; Duarte, Paulo; Fernandes, Horácio; Valcárcel, Daniel F.; Carvalho, Pedro J.; Silva, Carlos; Duarte, André S.; Neto, André; Sousa, Jorge; Batista, António J.N.; Carvalho, Bernardo B.
Shea, T J
This lecture begins with a definition of an accelerator control system, and then reviews the control system architectures that have been deployed at the larger accelerator facilities. This discussion naturally leads to identification of the major subsystems and their interfaces. We shall explore general strategies for integrating intelligent devices and signal processing subsystems based on gate arrays and programmable DSPs. The following topics will also be covered: physical packaging; timing and synchronization; local and global communication technologies; interfacing to machine protection systems; remote debugging; configuration management and source code control; and integration of commercial software tools. Several practical realizations will be presented.
Yunes, Maria C.; von Keyserlingk, Marina A. G.; Hötzel, Maria J.
Simple Summary The inclusion of societal input is needed for food animal production industries to retain their “social license to operate”. Little is known about the knowledge and attitudes of Brazilian citizens regarding food animal production systems. The aim of this study was to explore the beliefs and attitudes of Brazilians not associated with livestock production towards farm animal production systems. Overall, our participants expressed a preference for free-range, cage-free, and more “natural” production systems. They also expressed concerns with livestock production systems that limited the movement or expression of natural behaviours, particularly those that they associated with animal suffering or distress. They recognized farm animals as deserving respect and dignity beyond the provision of basic needs. Our findings indicate that Brazil’s current farm animal housing practices that are associated with restriction of movement may not align with societal expectations. Abstract The inclusion of societal input is needed for food animal production industries to retain their “social license to operate”; failure to engage with the public on this topic risks the long-term sustainability of these industries. The primary aim of this study was to explore the beliefs and attitudes of Brazilians citizens not associated with livestock production towards farm animal production. A related secondary aim was to identify the specific beliefs and attitudes towards systems that are associated with restriction of movement. Each participant was shown pictures representing two of five possible major food animal industries (laying hens, beef cattle, pregnant sows, lactating sows, and poultry meat). Participants were presented a six pages survey that included demographic questions plus two sets of two pictures and a series of questions pertaining to the pictures. Each set of pictures represented a particular industry where one picture represented a housing type that
Full Text Available The article deals with main tends of scientific research activities of Department of Control and Information Systems at the Faculty of Electrical Engineering of University of Zilina and its perspectives in this area.
Jiri Zahradnik; Karol Rastocny; Juraj Spalek
The article deals with main tends of scientific research activities of Department of Control and Information Systems at the Faculty of Electrical Engineering of University of Zilina and its perspectives in this area.
Lewis, Andrew D
This brief presents a description of a new modelling framework for nonlinear/geometric control theory. The framework is intended to be—and shown to be—feedback-invariant. As such, Tautological Control Systems provides a platform for understanding fundamental structural problems in geometric control theory. Part of the novelty of the text stems from the variety of regularity classes, e.g., Lipschitz, finitely differentiable, smooth, real analytic, with which it deals in a comprehensive and unified manner. The treatment of the important real analytic class especially reflects recent work on real analytic topologies by the author. Applied mathematicians interested in nonlinear and geometric control theory will find this brief of interest as a starting point for work in which feedback invariance is important. Graduate students working in control theory may also find Tautological Control Systems to be a stimulating starting point for their research.
Reset Control Systems addresses the analysis for reset control treating both its basic form which requires only that the state of the controller be reinitialized to zero (the reset action) each time the tracking error crosses zero (the reset condition), and some useful variations of the reset action (partial reset with fixed or variable reset percentage) and of the reset condition (fixed or variable reset band and anticipative reset). The issues regarding reset control – concepts and motivation; analysis tools; and the application of design methodologies to real-world examples – are given comprehensive coverage. The text opens with an historical perspective which moves from the seminal work of the Clegg integrator and Horowitz FORE to more recent approaches based on impulsive/hybrid control systems and explains the motivation for reset compensation. Preliminary material dealing with notation, basic definitions and results, and with the definition of the control problem under study is also included. The fo...
Solar sails are spacecraft that utilise the Solar Radiation Pressure, the force generated by impinging photons, to propel themselves. Conventional actuators are not suitable for controlling the attitude of solar sails therefore specific attitude control methods have been devised to tackle this. One of these methods is to change the centre of pressure with respect to the center of mass thus creating a torque. Reflectivity Control Devices (RCDs) have been proposed and successfully used to change the centre of pressure. Current methods that utilise RCDs have control authority over two axis only with no ability to control the torque about the normal of the sail surface. This thesis extends the state of the art and demonstrates 3-axis control by generating arbitrary torque vectors within a convex polyhedron. Two different RCD materials are considered, transmission and diffusion technologies both compatible with the proposed concept. A number of metrics have been developed which facilitate the comparison of different sail configurations. One of these metics is the sun map which is a graphic representation of the sun angles for which control authority is maintained. An iterative design process is presented which makes use of the metrics developed and aids in the design of a sail which meets the mission requirements and constraints. Moreover, the effects of different parameters on the performance of the proposed control concept are discussed. For example it is shown that by alternating the angle between the edge and middle RCDs the control authority increases. The concept's scalability has been investigated and a hybrid control scheme has been devised which makes use of both RCDs and reaction wheels. The RCDs are complemented by the reaction wheels to achieve higher slew rates while in turn the RCDs desaturate the reaction wheels. Finally, a number of simulations are conducted to verify the validity of the proposed concept.
Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar
the problems in previous research works. Moreover, the estimation of MEMS gyroscope bias is also inclueded in this estimator. The designed nonlinear attitude estimator is firstly tested in simulation environment and then implemented in an AHRS hardware for further experiments. Finally, the attitude estimation...
Epler, E.P.; Hanauer, S.H.; Oakes, L.C.
A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.
Mingying Huo; He Liao; Yanfang Liu; Naiming Qi
.... The results of stability analysis show that only some of the orbits are marginally stable. For unstable displaced orbits, linear quadratic regulator is employed to control the coupled attitude-orbit...
Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan
For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.
esteem scale developed by Adanijo and Oyefeso (1986), locus of control scale developed by Craig, Franklin and Andrew (1981) and attitude towards child adoption and adoptive parent questionnaire designed by the researchers. All measures used ...
Full Text Available Woven fabric quality depends on yarn properties at first, then weaving preparation and weaving processes. Defect control of grey and finished fabric is done manually on the lighted tables or automatically. Fabrics can be controlled by the help of the image analysis method. In image system the image of fabrics can be digitized by video camera and after storing controlled by the various processing. Recently neural networks, fuzzy logic, best wavelet packet model on automatic fabric inspection are developed. In this study the advantages and disadvantages of manual and automatic, on-line fabric inspection systems are given comparatively.
ACCESS (Actively-Corrected Coronograph for Exoplanet System Studies) was one of four medium-class exoplanet concepts selected for the NASA Astrophysics Strategic Mission Concept Study (ASMCS) program in 2008/2009. The ACCESS study evaluated four major coronograph concepts under a common space observatory. This paper describes the high precision pointing control system (PCS) baselined for this observatory.
TayyebTaher, M.; Esmaeilzadeh, S. Majid
This article presents an application of Model Predictive Controller (MPC) to the attitude control of a geostationary flexible satellite. SIMO model has been used for the geostationary satellite, using the Lagrange equations. Flexibility is also included in the modelling equations. The state space equations are expressed in order to simplify the controller. Naturally there is no specific tuning rule to find the best parameters of an MPC controller which fits the desired controller. Being an intelligence method for optimizing problem, Genetic Algorithm has been used for optimizing the performance of MPC controller by tuning the controller parameter due to minimum rise time, settling time, overshoot of the target point of the flexible structure and its mode shape amplitudes to make large attitude maneuvers possible. The model included geosynchronous orbit environment and geostationary satellite parameters. The simulation results of the flexible satellite with attitude maneuver shows the efficiency of proposed optimization method in comparison with LQR optimal controller.
In this work, we show how to computerize a helicopter to fly attitude axes controlled hover flight without the assistance of a pilot and without ever crashing. We start by developing a helicopter research test bed system including all hardware, software, and means for testing and training the helicopter to fly by computer. We select a Remote Controlled helicopter with a 5 ft. diameter rotor and 2.2 hp engine. We equip the helicopter with a payload of sensors, computers, navigation and telemetry equipment, and batteries. We develop a differential GPS system with cm accuracy and a ground computerized navigation system for six degrees of freedom (6-DoF) free flight while tracking navigation commands. We design feedback control loops with yet-to-be-determined gains for the five control "knobs" available to a flying radio-controlled (RC) miniature helicopter: engine throttle, main rotor collective pitch, longitudinal cyclic pitch, lateral cyclic pitch, and tail rotor collective pitch. We develop helicopter flight equations using fundamental dynamics, helicopter momentum theory and blade element theory. The helicopter flight equations include helicopter rotor equations of motions, helicopter rotor forces and moments, helicopter trim equations, helicopter stability derivatives, and a coupled fuselage-rotor helicopter 6-DoF model. The helicopter simulation also includes helicopter engine control equations, a helicopter aerodynamic model, and finally helicopter stability and control equations. The derivation of a set of non-linear equations of motion for the main rotor is a contribution of this thesis work. We design and build two special test stands for training and testing the helicopter to fly attitude axes controlled hover flight, starting with one axis at a time and progressing to multiple axes. The first test stand is built for teaching and testing controlled flight of elevation and yaw (i.e., directional control). The second test stand is built for teaching and
Full Text Available In view of the issue of rapid attitude maneuver control of agile satellite, this paper presents an attitude-tracking control algorithm with path planning based on the improved genetic algorithm, adaptive backstepping control as well as sliding mode control. The satellite applies double gimbal control moment gyro as actuator and is subjected to the external disturbance and uncertain inertia properties. Firstly, considering the comprehensive mathematical model of the agile satellite and the double gimbal control moment gyro, an improved genetic algorithm is proposed to solve the attitude path-planning problem. The goal is to find an energy optimal path which satisfies certain maneuverability under the constraints of the input saturation, actuator saturation, slew rate limit and singularity measurement limit. Then, the adaptive backstepping control and sliding mode control are adopted in the design of the attitude-tracking controller to track accurately the desired path comprised of the satellite attitude quaternion and velocity. Finally, simulation results indicate the robustness and good tracking performance of the derived controller as well as its ability to avert the singularity of double gimbal control moment gyro.
The study assessed the attitude of teachers in Lagos State to inspectors and inspection. The study took the form of a survey. Two hundred and fifty teachers from public secondary schools were selected as samples for the study using stratified random sampling technique. The instruments used for the data collection was the ...
Banse, R; Seise, J; Zerbes, N
Two experiments were conducted to investigate the psychometric properties of an Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) that was adapted to measure implicit attitudes towards homosexuality. In a first experiment, the validity of the Homosexuality-IAT was tested using a known group approach. Implicit and explicit attitudes were assessed in heterosexual and homosexual men and women (N = 101). The results provided compelling evidence for the convergent and discriminant validity of the Homosexuality-IAT as a measure of implicit attitudes. No evidence was found for two alternative explanations of IAT effects (familiarity with stimulus material and stereotype knowledge). The internal consistency of IAT scores was satisfactory (alpha s > .80), but retest correlations were lower. In a second experiment (N = 79) it was shown that uninformed participants were able to fake positive explicit but not implicit attitudes. Discrepancies between implicit and explicit attitudes towards homosexuality could be partially accounted for by individual differences in the motivation to control prejudiced behavior, thus providing independent evidence for the validity of the implicit attitude measure. Neither explicit nor implicit attitudes could be changed by persuasive messages. The results of both experiments are interpreted as evidence for a single construct account of implicit and explicit attitudes towards homosexuality.
Fourniols, J.-Y.; Soto-Romero, G.; Bony, F.; Vergnenègre, C.; Simonne, J.-J.; Esteve, D.; Albukerque, J.
MEMS technology now makes possible to produce active microdevices combining detection, signal processing, and data storage with accuracy and compactness. In view of their characteristics, it can be expected that such microsensors will be used extensively in space applications dedicated to micro and nano satellites. For this purpose, a specific investigation dealing with the complete development of a micro-earth sensor used for attitude control of Low Earth Orbit satellites is under realization and test. Based on an infrared uncooled 320x240 microbolometer the experimental characterization of the final active system consists of three microsensors linear arrays of 240 pixels of the same technology, radialy spaced at 120°, watching and receiving earth IR radiations. The transition between excited and non excited pixels will determine the IR image of the Earth/Space transition hidden in IR atmosphere response. Specific on-chip algorithms have been implemented to extract the transition and compute the attitude satellite position in roll and pitch. The complete physical system modeling of one linear 240 pixels array including earth models, optic characteristics, microbolometer behavioral models, mixed analog/digital electronics and associated algorithms is consistent (at +/-8% ) with the breadboard measurements.
Maria C. Yunes
Full Text Available The inclusion of societal input is needed for food animal production industries to retain their “social license to operate”; failure to engage with the public on this topic risks the long-term sustainability of these industries. The primary aim of this study was to explore the beliefs and attitudes of Brazilians citizens not associated with livestock production towards farm animal production. A related secondary aim was to identify the specific beliefs and attitudes towards systems that are associated with restriction of movement. Each participant was shown pictures representing two of five possible major food animal industries (laying hens, beef cattle, pregnant sows, lactating sows, and poultry meat. Participants were presented a six pages survey that included demographic questions plus two sets of two pictures and a series of questions pertaining to the pictures. Each set of pictures represented a particular industry where one picture represented a housing type that is associated with behavioural restrictions and the other picture represented a system that allowed for a greater degree of movement. Participants were asked their perceptions on the prevalence of each system in Brazil, then their preference of one picture vs. the other, and the reasons justifying their preference. Immediately following, the participant repeated the same exercise with the second set of two pictures representing another industry followed by the same series of questions as described above. Quantitative data were analysed with mixed effects logistic regression, and qualitative responses were coded into themes. The proportion of participants that believed animals are reared in confinement varied by animal production type: 23% (beef cattle, 82% (poultry, 81% (laying hens, and 60% (swine. A large majority (79% stated that farm animals are not well-treated in Brazil. Overall, participants preferred systems that were not associated with behavioural restriction. The
Yunes, Maria C; von Keyserlingk, Marina A G; Hötzel, Maria J
The inclusion of societal input is needed for food animal production industries to retain their "social license to operate"; failure to engage with the public on this topic risks the long-term sustainability of these industries. The primary aim of this study was to explore the beliefs and attitudes of Brazilians citizens not associated with livestock production towards farm animal production. A related secondary aim was to identify the specific beliefs and attitudes towards systems that are associated with restriction of movement. Each participant was shown pictures representing two of five possible major food animal industries (laying hens, beef cattle, pregnant sows, lactating sows, and poultry meat). Participants were presented a six pages survey that included demographic questions plus two sets of two pictures and a series of questions pertaining to the pictures. Each set of pictures represented a particular industry where one picture represented a housing type that is associated with behavioural restrictions and the other picture represented a system that allowed for a greater degree of movement. Participants were asked their perceptions on the prevalence of each system in Brazil, then their preference of one picture vs. the other, and the reasons justifying their preference. Immediately following, the participant repeated the same exercise with the second set of two pictures representing another industry followed by the same series of questions as described above. Quantitative data were analysed with mixed effects logistic regression, and qualitative responses were coded into themes. The proportion of participants that believed animals are reared in confinement varied by animal production type: 23% (beef cattle), 82% (poultry), 81% (laying hens), and 60% (swine). A large majority (79%) stated that farm animals are not well-treated in Brazil. Overall, participants preferred systems that were not associated with behavioural restriction. The preference for free
Albertos, Pedro; Blanke, Mogens; Isidori, Alberto; Schaufelberger, Walter; Sanz, Ricardo
The world of artificial systems is reaching complexity levels that es cape human understanding. Surface traffic, electricity distribution, air planes, mobile communications, etc. , are examples that demonstrate that we are running into problems that are beyond classical scientific or engi neering knowledge. There is an ongoing world-wide effort to understand these systems and develop models that can capture its behavior. The reason for this work is clear, if our lack of understanding deepens, we will lose our capability to control these systems and make they behave as we want. Researchers from many different fields are trying to understand and develop theories for complex man-made systems. This book presents re search from the perspective of control and systems theory. The book has grown out of activities in the research program Control of Complex Systems (COSY). The program has been sponsored by the Eu ropean Science Foundation (ESF) which for 25 years has been one of the leading players in stimula...
and features are added such a way that it can be also used for design of nonlinear control systems to achieve desired performance. It is very simple to learn this tool. One can easily use it with preliminary knowledge of DF and PPT methods.
Yang, Jian; Xie, Xiaofang; Wang, Yan
Based on the AHRS (Attitude and Heading Reference System) and PTZ (Pan/Tilt/Zoom) camera, we designed a video monitoring and tracking system. The overall structure of the system and the software design are given. The key technologies such as serial port communication and head attitude tracking are introduced, and the codes of the key part are given.
Full Text Available Internet congestion occurs when resource demands exceeds the network capacity. But, it is not the only reason. Congestion can happen on some users because some others user has higher sending rate. Then some users with lower sending rate will experience congestion. This partial congestion is caused by inexactly feedback. At this moment congestion are solved by the involvement of two controlling mechanisms. These mechanisms are flow/congestion control in the TCP source and Active Queue Management (AQM in the router. AQM will provide feedback to the source a kind of indication for the occurrence of the congestion in the router, whereas the source will adapt the sending rate appropriate with the feedback. These mechanisms are not enough to solve internet congestion problem completely. Therefore, this paper will explain internet congestion causes, weakness, and congestion control technique that researchers have been developed. To describe congestion system mechanisms and responses, the system will be simulated by Matlab.
National Aeronautics and Space Administration — To determine pointing and position vectors in both local and inertial coordinate frames, multi-spacecraft missions typically utilize separate attitude determination...
Tamer Mekky Ahmed Habib
Full Text Available The main goal of this research is to establish spacecraft orbit and attitude control algorithms based on extended Kalman filter which provides estimates of spacecraft orbital and attitude states. The control and estimation algorithms must be capable of dealing with the spacecraft conditions during the detumbling and attitude acquisition modes of operation. These conditions are characterized by nonlinearities represented by large initial attitude angles, large initial angular velocities, large initial attitude estimation error, and large initial position estimation error. All of the developed estimation and control algorithms are suitable for application to the next Egyptian scientific satellite, EGYPTSAT-2. The parameters of the case-study spacecraft are similar but not identical to the former Egyptian satellite EGYPTSAT-1. This is done because the parameters of EGYPTSAT-2 satellite have not been consolidated yet. The sensors utilized are gyro, magnetometer, and GPS. Gyro and magnetometer are utilized to provide measurements for the estimates of spacecraft attitude state vector where as magnetometer and GPS are utilized to provide measurements for the estimates of spacecraft orbital state vector.
Tavernier, Gilles; Campan, Genevieve
Since 1974, CNES has been involved in geostationary positioning. Among different entities participating in operations and their preparation, the Flight Dynamics Center (FDC) is in charge of performing the following tasks: orbit determination; attitude determination; computation, monitoring, and calibration of orbit maneuvers; computation, monitoring, and calibration of attitude maneuvers; and operational predictions. In order to fulfill this mission, the FDC receives telemetry from the satellite and localization measurements from ground stations (e.g., CNES, NASA, INTELSAT). These data are processed by space dynamics programs integrated in the MERCATOR system which is run on SUN workstations (UNIX O.S.). The main features of MERCATOR are redundancy, modularity, and flexibility: efficient, flexible, and user friendly man-machine interface; and four identical SUN stations redundantly linked in an Ethernet network. Each workstation can perform all the tasks from data acquisition to computation results dissemination through a video network. A team of four engineers can handle the space mechanics aspects of a complete geostationary positioning from the injection into a transfer orbit to the final maneuvers in the station-keeping window. MERCATOR has been or is to be used for operations related to more than ten geostationary positionings. Initially developed for geostationary satellites, MERCATOR's methodology was also used for satellite control centers and can be applied to a wide range of satellites and to future manned missions.
Castillo-Morales, A.; Eliche-Moral, M. C.; Pascual, S.; Villar, V.; Marino, R. A.; Cardiel, N.; Morales, I.; González, E.; Cedazo, R.; Serena, F.; Gallego, J.; Carrasco, E.; Vílchez, J. M.; Sánchez, F. M.; Gil de Paz, A.; García-Vargas, M. L.; The Megara Team
MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4 m telescope in La Palma. The MEGARA Control System will provide the capabilities to move the different mechanisms of the instrument, to readout the data from the detector controller and the necessary routines for the Inspector Panels, the MEGARA Observing Preparation Software Suite, the Data Factory and the Sequencer strategies.
Full Text Available In order to continue paper  which presented the nonlinear equations of the movement for small satellite, this paper presents some aspects regarding the synthesis of the attitude control. Afterthe movement equation linearization, the stability and command matrixes will be established and by using the gradient methods controller we will obtain them. Two attitude control cases will beanalysed: the reaction wheels and the micro thrusters. The results will be used in the project European Space Moon Orbit - ESMO, founded by the European Space Agency in which the POLITEHNICA University of Bucharest is involved.
Full Text Available The integrated 6-DOF orbit-attitude dynamical modeling and control have shown great importance in various missions, for example, formation flying and proximity operations. The integrated approach yields better performances than the separate one in terms of accuracy, efficiency, and agility. One challenge in the integrated approach is to find a unified representation for the 6-DOF motion with configuration space SE(3. Recently, exponential coordinates of SE(3 have been used in dynamics and control of the 6-DOF motion, however, only on the kinematical level. In this paper, we will improve the current method by adopting exponential coordinates on the dynamical level, by giving the relation between the second-order derivative of exponential coordinates and spacecraft’s accelerations. In this way, the 6-DOF motion in terms of exponential coordinates can be written as a second-order system with a quite compact form, to which a broader range of control theories, such as higher-order sliding modes, can be applied. For a demonstration purpose, a simple asymptotic tracking control law with almost global convergence is designed. Finally, the integrated modeling and control are applied to the body-fixed hovering over an asteroid and verified by a simulation, in which absolute motions of the spacecraft and asteroid are simulated separately.
Wen, Haowei; Yue, Xiaokui; Li, Peng; Yuan, Jianping
This paper presents a novel non-certainty-equivalence adaptive control method for the attitude tracking control problem of spacecraft with inertia uncertainties. The proposed immersion and invariance (I&I) based adaptation law provides a more direct and flexible approach to circumvent the limitations of the basic I&I method without employing any filter signal. By virtue of the adaptation high-gain equivalence property derived from the proposed adaptive method, the closed-loop adaptive system with a low adaptation gain could recover the high adaptation gain performance of the filter-based I&I method, and the resulting control torque demands during the initial transient has been significantly reduced. A special feature of this method is that the convergence of the parameter estimation error has been observably improved by utilizing an adaptation gain matrix instead of a single adaptation gain value. Numerical simulations are presented to highlight the various benefits of the proposed method compared with the certainty-equivalence-based control method and filter-based I&I control schemes.
Full Text Available This paper proposed a robust fault-tolerant control algorithm for satellite stabilization based on active disturbance rejection approach with artificial bee colony algorithm. The actuating mechanism of attitude control system consists of three working reaction flywheels and one spare reaction flywheel. The speed measurement of reaction flywheel is adopted for fault detection. If any reaction flywheel fault is detected, the corresponding fault flywheel is isolated and the spare reaction flywheel is activated to counteract the fault effect and ensure that the satellite is working safely and reliably. The active disturbance rejection approach is employed to design the controller, which handles input information with tracking differentiator, estimates system uncertainties with extended state observer, and generates control variables by state feedback and compensation. The designed active disturbance rejection controller is robust to both internal dynamics and external disturbances. The bandwidth parameter of extended state observer is optimized by the artificial bee colony algorithm so as to improve the performance of attitude control system. A series of simulation experiment results demonstrate the performance superiorities of the proposed robust fault-tolerant control algorithm.
Political and policy dynamics associated with local road systems planning, management, and financing merit special attention. This study: 1) analyzes stakeholder attitudes, knowledge, and engagement about financing for local road system management, t...
Luiz C. G. de Souza
Full Text Available An experimental attitude control algorithm design using prototypes can minimize space mission costs by reducing the number of errors transmitted to the next phase of the project. The Space Mechanics and Control Division (DMC of INPE is constructing a 3D simulator to supply the conditions for implementing and testing satellite control hardware and software. Satellite large angle maneuver makes the plant highly nonlinear and if the parameters of the system are not well determined, the plant can also present some level of uncertainty. As a result, controller designed by a linear control technique can have its performance and robustness degraded. In this paper the standard LQR linear controller and the SDRE controller associated with an SDRE filter are applied to design a controller for a nonlinear plant. The plant is similar to the DMC 3D satellite simulator where the unstructured uncertainties of the system are represented by process and measurements noise. In the sequel the State-Dependent Riccati Equation (SDRE method is used to design and test an attitude control algorithm based on gas jets and reaction wheel torques to perform large angle maneuver in three axes. The SDRE controller design takes into account the effects of the plant nonlinearities and system noise which represents uncertainty. The SDRE controller performance and robustness are tested during the transition phase from angular velocity reductions to normal mode of operation with stringent pointing accuracy using a switching control algorithm based on minimum system energy. This work serves to validate the numerical simulator model and to verify the functionality of the control algorithm designed by the SDRE method.
Ham, Norman D.
The Final Report on improvement of helicopter attitude stability by active control of the conventional swash plate covering the period from Nov. 1986 to Dec. 1993 is presented. A paper on the history, principles, and applications of helicopter individual-blade-control is included.
Macy, Jonathan T; Chassin, Laurie; Presson, Clark C
Several cross-sectional studies have examined factors associated with support for tobacco control policies. The current study utilized a longitudinal design to test smoking status and attitude toward smoking measured in adolescence as prospective predictors of support for tobacco control policies measured in adulthood. Participants (N = 4,834) were from a longitudinal study of a Midwestern community-based sample. Hierarchical multiple regression analyses tested adolescent smoking status and attitude toward smoking as prospective predictors (after controlling for sociodemographic factors, adult smoking status, and adult attitude toward smoking) of support for regulation of smoking in public places, discussion of the dangers of smoking in public schools, prohibiting smoking in bars, eliminating smoking on television and in movies, prohibiting smoking in restaurants, and increasing taxes on cigarettes. Participants who smoked during adolescence demonstrated more support for discussion of the dangers of smoking in public schools and less support for increasing taxes on cigarettes but only among those who smoked as adults. Those with more positive attitudes toward smoking during adolescence demonstrated less support as adults for prohibiting smoking in bars and eliminating smoking on television and in movies. Moreover, a significant interaction indicated that those with more positive attitudes toward smoking as adolescents demonstrated less support as adults for prohibiting smoking in restaurants, but only if they became parents as adults. This study's findings suggest that interventions designed to deter adolescent smoking may have future benefits in increasing support for tobacco control policies.
Smith, J.D.; Ramamoorthy, S.; Tang, Yong N.
The NSLS consists of two storage rings, a booster and a linac. A major upgrade of the control system (installed in 1978) was undertaken and has been completed. The computer architecture is being changed from a three level star-network to a two level distributed system. The microprocessor subsystem, host computer and workstations, communication link and the main software components are being upgraded or replaced. Since the NSLS rings operate twenty four hours a day a year with minimum maintenance time, the key requirement during the upgrade phase is a non-disruptive transition with minimum downtime. Concurrent with the upgrade, some immediate improvements were required. This paper describes the various components of the upgraded system and outlines the future plans.
Nag, S.; Li, A.
Distributed Space Missions (DSMs) such as formation flight and constellations, are being recognized as important solutions to increase measurement samples over space and time. Given the increasingly accurate attitude control systems emerging in the commercial market, small spacecraft now have the ability to slew and point within few minutes of notice. In spite of hardware development in CubeSats at the payload (e.g. NASA InVEST) and subsystems (e.g. Blue Canyon Technologies), software development for tradespace analysis in constellation design (e.g. Goddard's TAT-C), planning and scheduling development in single spacecraft (e.g. GEO-CAPE) and aerial flight path optimizations for UAVs (e.g. NASA Sensor Web), there is a gap in open-source, open-access software tools for planning and scheduling distributed satellite operations in terms of pointing and observing targets. This paper will demonstrate results from a tool being developed for scheduling pointing operations of narrow field-of-view (FOV) sensors over mission lifetime to maximize metrics such as global coverage and revisit statistics. Past research has shown the need for at least fourteen satellites to cover the Earth globally everyday using a LandSat-like sensor. Increasing the FOV three times reduces the need to four satellites, however adds image distortion and BRDF complexities to the observed reflectance. If narrow FOV sensors on a small satellite constellation were commanded using robust algorithms to slew their sensor dynamically, they would be able to coordinately cover the global landmass much faster without compensating for spatial resolution or BRDF effects. Our algorithm to optimize constellation satellite pointing is based on a dynamic programming approach under the constraints of orbital mechanics and existing attitude control systems for small satellites. As a case study for our algorithm, we minimize the time required to cover the 17000 Landsat images with maximum signal to noise ratio fall
Roithmayr, Carlos M.; Karlgaard, Christopher D.; Kumar, Renjith R.; Seywald, Hans; Bose, David M.
Several laws are designed for simultaneous control of the orientation of an Earth-pointing spacecraft, the energy stored by counter-rotating flywheels, and the angular momentum of the flywheels and control moment gyroscopes used together as an integrated set of actuators for attitude control. General, nonlinear equations of motion are presented in vector-dyadic form, and used to obtain approximate expressions which are then linearized in preparation for design of control laws that include feedback of flywheel kinetic energy error as a means of compensating for damping exerted by rotor bearings. Two flywheel steering laws are developed such that torque commanded by an attitude control law is achieved while energy is stored or discharged at the required rate. Using the International Space Station as an example, numerical simulations are performed to demonstrate control about a torque equilibrium attitude, and illustrate the benefits of kinetic energy error feedback. Control laws for attitude hold are also developed, and used to show the amount of propellant that can be saved when flywheels assist the CMGs. Nonlinear control laws for large-angle slew maneuvers perform well, but excessive momentum is required to reorient a vehicle like the International Space Station.
Akinyemi, Felicia O.
Technology use is evident in all spheres of human endeavour. Focusing on technology use in education, this paper examines teachers' attitudes towards geographic information system (GIS). An assessment was made of GIS teachers in Rwandan secondary schools. Key areas covered include how GIS is implemented in schools, teachers' attitudes and…
MOHAMMED, M. A. SI; BOUSSADIA, H.; BELLAR, A.; ADNANE, A.
This paper presents the design of Low Earth Orbit (LEO) micro-satellite attitude controller using reaction wheels, and under actuator faults. Firstly, a backstepping controller is developed when the actuator is fault-free. Then, a fault tolerant controller is designed to compensate the actuator fault. Two types of this latter are considered (additive and multiplicative faults). The presented control strategy is based on adaptive backstepping technique. The simulation results clearly demonstrate the effectiveness of the presented technique.
Full Text Available A robust control allocation scheme is developed for rigid spacecraft attitude stabilization in the presence of actuator partial loss fault, actuator failure, and actuator misalignment. First, a neural network fault detection scheme is proposed, Second, an adaptive attitude tracking strategy is employed which can realize fault tolerance control under the actuator partial loss and actuator failure within λmin=0.5. The attitude tracking and faults detection are always here during the procedure. Once the fault occurred which could not guaranteed the attitude stable for 30 s, the robust control allocation strategy is generated automatically. The robust control allocation compensates the control effectiveness uncertainty which caused the actuator misalignment. The unknown disturbances, uncertain inertia matrix, and even actuator error with limited actuators are all considered in the controller design process. All are achieved with inexpensive online computations. Numerical results are also presented that not only highlight the closed-loop performance benefits of the control law derived here but also illustrate its great robustness.
Idelchik, Michael S. (Inventor)
A control system and method of controlling a gas turbine engine. The control system receives an error signal and processes the error signal to form a primary fuel control signal. The control system also receives at least one anticipatory demand signal and processes the signal to form an anticipatory fuel control signal. The control system adjusts the value of the anticipatory fuel control signal based on the value of the error signal to form an adjusted anticipatory signal and then the adjusted anticipatory fuel control signal and the primary fuel control signal are combined to form a fuel command signal.
Bolin, Aaron U
Academic dishonesty is a persistent and pervasive problem on college campuses. Researchers have suggested a variety of factors that influence academic dishonesty. The present study is an examination of the roles of self-control, attitude toward academic dishonesty, and perceived opportunity in predicting academic dishonesty. The dataset consisted of 853 survey responses from university students across the United States. The results showed that attitude toward academic dishonesty mediated the relationship between self-control and academic dishonesty and also between perceived opportunity and academic dishonesty. Implications of these findings are briefly discussed.
Full Text Available The paper describes the development of a microsatellite attitude determination and control subsystem (ADCS and verification of its functionality by software-in-the-loop (SIL method. The role of ADCS is to provide attitude control functions, including the de-tumbling and stabilizing the satellite angular velocity, and as well as estimating the orbit and attitude information during the satellite operation. In Taiwan, Air Force Institute of Technology (AFIT, dedicating for students to design experimental low earth orbit micro-satellite, called AFITsat. For AFITsat, the operation of the ADCS consists of three modes which are initialization mode, detumbling mode, and normal mode, respectively. During the initialization mode, ADCS collects the early orbit measurement data from various sensors so that the data can be downlinked to the ground station for further analysis. As particularly emphasized in this paper, during the detumbling mode, ADCS implements the thrusters in plus-wide modulation control method to decrease the satellite angular velocity. ADCS provides the attitude determination function for the estimation of the satellite state, during normal mode. The three modes of microsatellite adopted Kalman filter algorithm estimate microsatellite attitude. This paper will discuss using the SIL validation ADCS function and verify its feasibility.
Logan, J.B., Fluor Daniel Hanford
This is a direct revision to Rev. 0 of the BLTC Control System Software. The entire document is being revised and released as HNF-SD-FF-CSWD-025, Rev 1. The changes incorporated by this revision include addition of a feature to automate the sodium drain when removing assemblies from sodium wetted facilities. Other changes eliminate locked in alarms during cold operation and improve the function of the Oxygen Analyzer. See FCN-620498 for further details regarding these changes. Note the change in the document number prefix, in accordance with HNF-MD-003.
Otani, Koichi; Suzuki, Akihito; Matsumoto, Yoshihiko; Sadahiro, Ryoichi; Enokido, Masanori
The affectionless control parenting has been associated with depression in recipients. The aim of this study was to examine the effect of this parenting style on dysfunctional attitudes predisposing to depression. The subjects were 666 Japanese volunteers. Perceived parental rearing was evaluated by the Parental Bonding Instrument, which has the care and protection subscales. Parental rearing was classified into four types, i.e., optimal parenting (high care/low protection), affectionate constraint (high care/high protection), neglectful parenting (low care/low protection), and affectionless control (low care/high protection). Dysfunctional attitudes were evaluated by the 24-item Dysfunctional Attitude Scale, which has the achievement, dependency and self-control subscales. Males with paternal affectionless control had higher achievement scores than those with paternal optimal parenting (P=.016). Similarly, females with maternal affectionless control had higher achievement scores than those with maternal optimal parenting (P=.016). The present study suggests that affectionless control by the same-sex parents increases dysfunctional attitudes about achievement. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
Sang Cheol Lee
Full Text Available This paper presents an algorithm for velocity-aided attitude estimation for helicopter aircraft using a microelectromechanical system inertial-measurement unit. In general, high- performance gyroscopes are used for estimating the attitude of a helicopter, but this type of sensor is very expensive. When designing a cost-effective attitude system, attitude can be estimated by fusing a low cost accelerometer and a gyro, but the disadvantage of this method is its relatively low accuracy. The accelerometer output includes a component that occurs primarily as the aircraft turns, as well as the gravitational acceleration. When estimating attitude, the accelerometer measurement terms other than gravitational ones can be considered as disturbances. Therefore, errors increase in accordance with the flight dynamics. The proposed algorithm is designed for using velocity as an aid for high accuracy at low cost. It effectively eliminates the disturbances of accelerometer measurements using the airspeed. The algorithm was verified using helicopter experimental data. The algorithm performance was confirmed through a comparison with an attitude estimate obtained from an attitude heading reference system based on a high accuracy optic gyro, which was employed as core attitude equipment in the helicopter.
Lee, Sang Cheol; Hong, Sung Kyung
This paper presents an algorithm for velocity-aided attitude estimation for helicopter aircraft using a microelectromechanical system inertial-measurement unit. In general, high- performance gyroscopes are used for estimating the attitude of a helicopter, but this type of sensor is very expensive. When designing a cost-effective attitude system, attitude can be estimated by fusing a low cost accelerometer and a gyro, but the disadvantage of this method is its relatively low accuracy. The accelerometer output includes a component that occurs primarily as the aircraft turns, as well as the gravitational acceleration. When estimating attitude, the accelerometer measurement terms other than gravitational ones can be considered as disturbances. Therefore, errors increase in accordance with the flight dynamics. The proposed algorithm is designed for using velocity as an aid for high accuracy at low cost. It effectively eliminates the disturbances of accelerometer measurements using the airspeed. The algorithm was verified using helicopter experimental data. The algorithm performance was confirmed through a comparison with an attitude estimate obtained from an attitude heading reference system based on a high accuracy optic gyro, which was employed as core attitude equipment in the helicopter.
With the ever-growing desire for mankind to reach destinations whose distances had been deemed impossible to transit, the largest rocket known to man was designed and is being developed. The Space Launch System (SLS), National Aeronautics and Space Administrationâ€™s (NASA) solution for deep space travel, will begin its missions with the launch of Exploration Mission 1 (EM-1) and Exploration Mission 2 (EM-2). In order to accommodate the larger rocket, Kennedy Space Center made crucial upgrades to its existing facilities. At Launch Complex 39B, an entirely new Environmental Control System (ECS) was developed to supply the vehicle with the appropriate air or nitrogen gas mixture for launch. The new ECS displays must undergo Validation and Verification (V&V) using testing procedures developed to meet this requirement.
Ham, N. D.
The novel active control system presented for helicopter rotor aerodynamic and aeroelastic problems involves the individual control of each blade in the rotating frame over a wide range of frequencies (up to the sixth harmonic of rotor speed). This Individual Blade Control (IBC) system controls blade pitch by means of broadband electrohydraulic actuators attached to the swash plate (in the case of three blades) or individually to each blade, using acceleratometer signals to furnish control commands to the actuators. Attention is given to IBC's application to blade lag, flapping, and bending dynamics. It is shown that gust alleviation, attitude stabilization, vibration alleviation, and air/ground resonance suppression, are all achievable with a conventional helicopter swash plate.
Sørensen, Bjarne Taulo; Barcellos, Marcia Dutra de; Olsen, Nina Veflen; Verbeke, Wim; Scholderer, Joachim
Existing research on public attitudes towards agricultural production systems is largely descriptive, abstracting from the processes through which members of the general public generate their evaluations of such systems. The present paper adopts a systems perspective on such evaluations, understanding them as embedded into a wider attitude system that consists of attitudes towards objects of different abstraction levels, ranging from personal value orientations over general socio-political attitudes to evaluations of specific characteristics of agricultural production systems. It is assumed that evaluative affect propagates through the system in such a way that the system becomes evaluatively consistent and operates as a schema for the generation of evaluative judgments. In the empirical part of the paper, the causal structure of an attitude system from which people derive their evaluations of pork production systems was modelled. The analysis was based on data from a cross-national survey involving 1931 participants from Belgium, Denmark, Germany and Poland. The survey questionnaire contained measures of personal value orientations and attitudes towards environment and nature, industrial food production, food and the environment, technological progress, animal welfare, local employment and local economy. In addition, the survey included a conjoint task by which participants' evaluations of the importance of production system attributes were measured. The data were analysed by means of causal search algorithms and structural equation models. The results suggest that evaluative judgments of the importance of pork production system attributes are generated in a schematic manner, driven by personal value orientations. The effect of personal value orientations was strong and largely unmediated by attitudes of an intermediate level of generality, suggesting that the dependent variables in the particular attitude system that was modelled here can be understood as value
Jang, Jiann-Woei; Yang, Lee; Fritz, Mathew; Nguyen, Louis H.; Johnson, Wyatt R.; Hart, Jeremy J.
The Morpheus Lander is a vertical takeoff and landing test bed vehicle developed to demonstrate the system performance of the Guidance, Navigation and Control (GN&C) system capability for the integrated autonomous landing and hazard avoidance system hardware and software. The Morpheus flight control system design must be robust to various mission profiles. This paper presents a design methodology for employing numerical optimization to develop the Morpheus flight control system. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics and propellant slosh. Under the assumption that the Morpheus time-varying dynamics and control system can be frozen over a short period of time, the flight controllers are designed to stabilize all selected frozen-time control systems in the presence of parametric uncertainty. Both control gains in the inner attitude control loop and guidance gains in the outer position control loop are designed to maximize the vehicle performance while ensuring robustness. The flight control system designs provided herein have been demonstrated to provide stable control systems in both Draper Ares Stability Analysis Tool (ASAT) and the NASA/JSC Trick-based Morpheus time domain simulation.
Li, Yulun; Yang, Zhen; Ma, Xiaoshan; Ni, Wei
The vibration has an important influence on space-borne TDICCD imaging quality. It is generally aroused by an interaction between satellite jitter and attitude control. Previous modeling for this coupling relation is mainly concentrating on accurate modal analysis, transfer path and damping design, etc. Nevertheless, when controlling attitude, the coupling terms among three body axes are usually ignored. This is what we try to study in this manuscript. Firstly, a simplified formulation dedicated to this problem is established. Secondly, we use Dymola 2016 to execute the simulation model profiting Modelica synchronous feature, which has been proposed in recent years. The results demonstrate that the studied effect can introduce additional oscillatory modes and lead the attitude stabilization process slower. In addition, when fully stabilized, there seems time-statistically no difference but it still intensifies the motion-blur by a tiny amount. We state that this effect might be worth considering in image restoration.
Full Text Available A parallel configuration using two 3-degree-of-freedom (3-DOF spherical electromagnetic momentum exchange actuators is investigated for large angle spacecraft attitude maneuvers. First, the full dynamic equations of motion for the spacecraft system are derived by the Newton-Euler method. To facilitate computation, virtual gimbal coordinate frames are established. Second, a nonlinear control law in terms of quaternions is developed via backstepping method. The proposed control law compensates the coupling torques arising from the spacecraft rotation, and is robust against the external disturbances. Then, the singularity problem is analyzed. To avoid singularities, a modified weighed Moore-Pseudo inverse velocity steering law based on null motion is proposed. The weighted matrices are carefully designed to switch the actuators and redistribute the control torques. The null motion is used to reorient the rotor away from the tilt angle saturation state. Finally, numerical simulations of rest-to-rest maneuvers are performed to validate the effectiveness of the proposed method.
Bai,Fengshuang; Yin,Yixin; Tu,Xuyan; Zhang,Ying
This paper provides the system and conception of the Personification Control System (PCS) on the basis of Intelligent Control System based on Artificial life (ICS/AL), Artificial Emotion, Humanoid Control, and Intelligent Control System based on Field bus. According to system science and deciding of organize of biology, the Pyramid System of PCS are created. Then Pyramid System of PCS which is made up of PCS1/H, PCS1/S, PCS1/O, PCS1/C and PCS1/G is described.
Reshmin, S. A.
The time-optimal problem is considered for a nonlinear Lagrangian system with one degree of freedom. The system is controlled by a force bounded in absolute value, and all noncontrol forces are potential.We study the properties of optimal synthesis on the phase cylinder and indicate the conditions under which it has the simplest structure, namely, involves at most one switching for any initial conditions. The approach is used to specify the structure of the well-known solution in the classical problem on the time-optimal satellite attitude transition maneuver in the orbit plane.
Oudekerk, Barbara A.; Allen, Joseph P.; Hafen, Christopher A.; Hessel, Elenda T.; Szwedo, David E.; Spilker, Ann
Maternal and paternal psychological control, peer attitudes, and the interaction of psychological control and peer attitudes at age 13 were examined as predictors of risky sexual behavior before age 16 in a community sample of 181 youth followed from age 13 to 16. Maternal psychological control moderated the link between peer attitudes and sexual behavior. Peer acceptance of early sex predicted greater risky sexual behaviors, but only for teens whose mothers engaged in high levels of psychological control. Paternal psychological control demonstrated the same moderating effect for girls; for boys, however, high levels of paternal control predicted risky sex regardless of peer attitudes. Results are consistent with the theory that peer influences do not replace parental influences with regard to adolescent sexual behavior; rather, parental practices continue to serve an important role either directly forecasting sexual behavior or moderating the link between peer attitudes and sexual behavior. PMID:25328265
Eure, Kenneth W.; Quach, Cuong Chi; Vazquez, Sixto L.; Hogge, Edward F.; Hill, Boyd L.
Unmanned Aerial Vehicles (UAV) are playing an increasing role in aviation. Various methods exist for the computation of UAV attitude based on low cost microelectromechanical systems (MEMS) and Global Positioning System (GPS) receivers. There has been a recent increase in UAV autonomy as sensors are becoming more compact and onboard processing power has increased significantly. Correct UAV attitude estimation will play a critical role in navigation and separation assurance as UAVs share airspace with civil air traffic. This paper describes attitude estimation derived by post-processing data from a small low cost Inertial Navigation System (INS) recorded during the flight of a subscale commercial off the shelf (COTS) UAV. Two discrete time attitude estimation schemes are presented here in detail. The first is an adaptation of the Kalman Filter to accommodate nonlinear systems, the Extended Kalman Filter (EKF). The EKF returns quaternion estimates of the UAV attitude based on MEMS gyro, magnetometer, accelerometer, and pitot tube inputs. The second scheme is the complementary filter which is a simpler algorithm that splits the sensor frequency spectrum based on noise characteristics. The necessity to correct both filters for gravity measurement errors during turning maneuvers is demonstrated. It is shown that the proposed algorithms may be used to estimate UAV attitude. The effects of vibration on sensor measurements are discussed. Heuristic tuning comments pertaining to sensor filtering and gain selection to achieve acceptable performance during flight are given. Comparisons of attitude estimation performance are made between the EKF and the complementary filter.
Shao, Taizhou; Long, Haihui; Zhao, Jiankang; Xia, Xuan; Yang, Guang
This paper researches the small-size unmanned helicopter attitude control problem with actuator saturation limit. Traditional approach for this problem is often based on an accurate dynamic model which is complicated and difficult to achieve in engineering. In this paper, we propose an anti-windup PID approach which does not rely on sophicated helicopter dynamic model. The anti-windup PID controller is established by adding a phase-lead compensator to the conventional PID controller. The performance and merits of this proposed controller are exemplified by the simulations between the conventional PID controller and the anti-windup PID controller.
Full Text Available In Inertial Navigation Systems (INS, the attitude estimated from gyro measurements by the Kalman filter is subject to an unbound error growth during the stand-alone mode, especially for land vehicle applications using low-cost sensors. To improve the attitude estimation of a land vehicle, this paper applies a fuzzy expert system to assist in multi-sensor data fusion from MEMS accelerometers, MEMS gyroscopes and a digital compass based on their complementary motion detection characteristics. Field test results have shown that drift-free and smooth attitude estimation can be achieved and will lead to a significant performance improvement for velocity and position estimation.
Andryani, Dwinta; Kurniawati
Penelitian ini dilakukan untuk menganalisa pengaruh Attitude, Subjective Norm, PerceivedBehavioral Control terhadap Intention to Purchase. Data dikumpulkan langsung melaluipenyebaran kuesioner kepada 170 orang responden. Teknik pengambilan sampel dalam penelitianini adalah dengan menggunakan purposive sampling. Hasil empiris dari penelitian inimenggunakan program Statistical Package for the Social Science (SPSS) dengan metode analisisstructural equation model (SEM). Hasil pengujian hipotesis ...
This research was carried out to assess the role of dysfunctional attitudes, outcomes of psychology in substance abuse behaviors of subject were referred to addiction treatment center in the city of Bandar Abbas, and to compare the with the control group. Methods: This is a retrospective study in which 100 subject substance abusers were compared with 100 subject s of control group who were selected using convenience sampling and were also demographically matched. Data were gathered using a demographic questionnaire, clinical interview, dysfunctional attitudes scale (DAS, Depression Anxiety Stress Scale (DASS. The data were analyzed via descriptive statistic method, T- Test and chi-square and variance analysis. Findings: Findings indicated that in comparison with control group, subject of substance abusers had experienced more stress, anxiety, depression, had shown a cognitively more percent of them dysfunctional attitudes in comparison with control group. Results: The results suggested that the dysfunctional attitudes could be as a Vulnerability Factor that increase abuse of substance consequently use of cognitive therapy could be helpful and effective in prevention and treatment of the addicts.
Gadzella, Bernadette M.; And Others
The study investigated (a) relationships between measures on study habits and attitudes, locus of control, achieving tendency, and semester grade-point averages (SGPA), (b) differences between the sexes on the above mentioned variables, and (c) best predictor of SGPA. The subjects were 39 males and 81 females. There were a number of significant…
Martin, Nancy K.; Yin, Zenong; Mayall, Hayley
The purpose of this study was to report the psychometric properties of the revised Attitudes and Beliefs of Classroom Control Inventory (ABCC-R). Data were collected from 489 participants via the ABCC-R, Teacher Efficacy Scale, Problems in School Questionnaire, and a demographic questionnaire. Results were in keeping with the construct. The…
Hostetler, Andrew J.
A person-environment approach was used to explore the relationship between community involvement and attitudes toward aging among middle-age and older lesbians and gay men. Specifically, this study investigated the relationships between participation in gay community activities, perceived control, and aging-related concerns among two…
Brown, Rachael; Ogden, Jane
The present study compared the modelling and control theories of parental influence on children's eating attitudes and behaviour with a focus on snack foods. Matched questionnaires describing reported snack intake, eating motivations and body dissatisfaction were completed by 112 parent/child pairs. Parents completed additional items relating to…
Ramirez, Amelie G.; Velez, Luis F.; Chalela, Patricia; Grussendorf, Jeannie; McAlister, Alfred L.
This study applied self-efficacy theory to assess empowerment to advocate on behalf of tobacco control policies. The Youth Tobacco Survey with added policy advocacy self-efficacy, attitudes, and outcome expectations scales was given to 9,177 high school students in Texas. Asians showed the lowest prevalence of experimentation and current smoking,…
McComas, David; O'Donnell, James R., Jr.; Andrews, Stephen F.
This paper presents an overview of the attitude control subsystem flight software development process, identifies how the process has changed due to automatic code generation, analyzes each software development phase in detail, and concludes with a summary of our lessons learned.
TERMS EOARD, Navigation, Comunications & Guidance, Complex Systems 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON JAMES LAWTON Ph...Switching Systems : Controllability and Control Design 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5d. TASK NUMBER 6. AUTHOR(S) Professor...ABSTRACT Motivated by the need of dealing with physical systems that exhibit a more complicated behavior than those normally described by
This paper categorizes the qualitative behavior of the Command and Control Segment (CCS) differential correction algorithm as applied to attitude estimation using simultaneous spin axis sun angle and Earth cord length measurements. The categories of interest are the domains of convergence, divergence, and their boundaries. Three series of plots are discussed that show the dependence of the estimation algorithm on the vehicle radius, the sun/Earth angle, and the spacecraft attitude. Common qualitative dynamics to all three series are tabulated and discussed. Out-of-limits conditions for the estimation algorithm are identified and discussed.
Fuad A. A.TRAYEK; Sharifah SARIAH SYED HASSAN
Learning management system (LMS) is a learning platform for both full time and distant learning students at the International Islamic University in Malaysia (IIUM). LMS becomes a tool for IIUM to disseminate information and learning resources to the students. The objectives of this study were to Ø investigate students' attitudes toward the use of LMS, Ø to verify the impact of perceived usefulness and perceived ease of use on attitude towards use of learning management system, Ø to e...
Sammarone, Dino G.
A system for controlling the environment of an enclosed area in nuclear reactor installations. The system permits the changing of the environment from nitrogen to air, or from air to nitrogen, without the release of any radioactivity or process gas to the outside atmosphere. In changing from a nitrogen to an air environment, oxygen is inserted into the enclosed area at the same rate which the nitrogen-oxygen gas mixture is removed from the enclosed area. The nitrogen-oxygen gas mixture removed from the enclosed area is mixed with hydrogen, the hydrogen recombining with the oxygen present in the gas to form water. The water is then removed from the system and, if it contains any radioactive products, can be utilized to form concrete, which can then be transferred to a licensed burial site. The process gas is purified further by stripping it of carbon dioxide and then distilling it to remove any xenon, krypton, and other fission or non-condensable gases. The pure nitrogen is stored as either a cryogenic liquid or a gas. In changing from an air to nitrogen environment, the gas is removed from the enclosed area, mixed with hydrogen to remove the oxygen present, dried, passed through adsorption beds to remove any fission gases, and reinserted into the enclosed area. Additionally, the nitrogen stored during the nitrogen to air change, is inserted into the enclosed area, the nitrogen from both sources being inserted into the enclosed area at the same rate as the removal of the gas from the containment area. As designed, the amount of nitrogen stored during the nitrogen to air change substantially equals that required to replace oxygen removed during an air to nitrogen change.
This book describes how control of distributed systems can be advanced by an integration of control, communication, and computation. The global control objectives are met by judicious combinations of local and nonlocal observations taking advantage of various forms of communication exchanges between distributed controllers. Control architectures are considered according to increasing degrees of cooperation of local controllers: fully distributed or decentralized control, control with communication between controllers, coordination control, and multilevel control. The book covers also topics bridging computer science, communication, and control, like communication for control of networks, average consensus for distributed systems, and modeling and verification of discrete and of hybrid systems. Examples and case studies are introduced in the first part of the text and developed throughout the book. They include: control of underwater vehicles, automated-guided vehicles on a container terminal, contro...
Rong, Ye; Glozier, Nick; Luscombe, Georgina M; Davenport, Tracey A; Huang, Yueqin; Hickie, Ian B
Establishing an evidence-based method of improving knowledge and attitudes concerning depression has been identified as a priority in Chinese medical education. The purpose of this study was to determine whether a self-directed learning strategy as a part of student-centred education improved knowledge of and attitudes towards depression among Chinese medical students. A controlled trial in which 205 medical students were allocated to one of two groups: didactic teaching (DT) group or a combined didactic teaching and self-directed learning (DT/SDL) group. The DT/SDL group continued having a series of learning activities after both groups had a lecture on depression together. Student's knowledge and attitudes were assessed immediately after the activities, one month and six months later. The intervention (DT/SDL) group showed substantially greater improvements in recognition of depression as a major health issue and identifying helpful treatments than the DT group. Only the DT/SDL group demonstrated any improvement in attitudes. This improvement was sustained over six months. Self-directed learning is an effective education strategy in improving medical students' knowledge of and attitudes towards depression.
Davenport Tracey A
Full Text Available Abstract Background Establishing an evidence-based method of improving knowledge and attitudes concerning depression has been identified as a priority in Chinese medical education. The purpose of this study was to determine whether a self-directed learning strategy as a part of student-centred education improved knowledge of and attitudes towards depression among Chinese medical students. Methods A controlled trial in which 205 medical students were allocated to one of two groups: didactic teaching (DT group or a combined didactic teaching and self-directed learning (DT/SDL group. The DT/SDL group continued having a series of learning activities after both groups had a lecture on depression together. Student's knowledge and attitudes were assessed immediately after the activities, one month and six months later. Results The intervention (DT/SDL group showed substantially greater improvements in recognition of depression as a major health issue and identifying helpful treatments than the DT group. Only the DT/SDL group demonstrated any improvement in attitudes. This improvement was sustained over six months. Conclusions Self-directed learning is an effective education strategy in improving medical students' knowledge of and attitudes towards depression.
Mahmoud, Magdi S.; Rahman, Mohamed Saif Ur; AL-Sunni, Fouad M.
The microgrid has made its mark in distributed generation and has attracted widespread research. However, microgrid is a complex system which needs to be viewed from an intelligent system of systems perspective. In this paper, a network control system of systems is designed for the islanded microgrid system consisting of three distributed generation units as three subsystems supplying a load. The controller stabilises the microgrid system in the presence of communication infractions such as packet dropouts and delays. Simulation results are included to elucidate the effectiveness of the proposed control strategy.
Trentelman, Harry L.; Stoorvogel, Antonie Arij; Hautus, Malo
Control Theory for Linear Systems deals with the mathematical theory of feedback control of linear systems. It treats a wide range of control synthesis problems for linear state space systems with inputs and outputs. The book provides a treatment of these problems using state space methods, often
Full Text Available In this paper a controllability study of different actuator configurations consisting of magnetic torquers, reaction wheels and a gravity boom is presented. The theoretical analysis is performed with use of controllability gramians, and simulation results with the different configurations are presented and compared regarding settling time and power consumption to substantiate the theoretical analysis. A reference model is also introduced to show how the power consumption can he lowered to the same magnitude as when magnetic torquers are used, without degrading the satellite response significantly.
Price, William D.
addressed via coordinate transformation. It is shown that driftless nonlinear systems that do not meet Brockett's conditions for coordinate transformation can be augmented such that they can be transformed into the Brockett's canonical form, which is nonholonomic. It is also shown that the kinematics for quaternion systems can be represented by a nonholonomic integrator. Then, a discontinuous controller designed for nonholonomic systems is applied. Examples of various applications for dual quaternion systems are given including spacecraft attitude and position control and robotics.
Abdolaziz Hagh Negahdar
Full Text Available Background & Objective: Infection control in dental centers is affected by the persons’ attitude and knowledge about mechanisms of infection transmission. This study was designed to evaluate the knowledge and the attitude of Shiraz dentists about infection control during intraoral radiographies preparation. Materials & Methods: In this cross-sectional, and analytical research, the attitude and the knowledge of 45 male and 25 female, randomly selected dentists, were obtained through completion of a researcher- planed questioner which its validity and reliability had been confirmed. Data were analyzed using Cronbach`s alpha, one-way ANOVA, student’s t-test, and Pearson’s correlation coefficient in SPSS (V.21. Results: The average of the dentists’ age was 40.59±10.72 and their average occupational experience was 13.49±9.75 years. The mean score obtained for knowledge about infection control during intraoral radiographic procedures was less than fifty percent of total obtainable score, and was assessed as weak knowledge. There was no significant difference in the level of knowledge between studied male and female dentists (P>0.05. In addition, no significant relationship was detected between level, age/experience, and the university of education (P>0.05. The attitude of the dentists about infection control during intraoral radiography preparation assessed as moderate to good level. Conclusions: The results showed that the main reason for the present problems is insufficient knowledge of the dentists in related subjects. Therefore, the solution, which is recommended among dentists, is to raise their awareness and to change their attitudes and culture in order to improve their performance.
This document defines requirements for an upgrade of the Sodium Removal System (SRS) control system. The upgrade is being performed to solve a number of maintainability and operability issues. The upgraded system will provide the same functions, controls and interlocks as the present system, and in addition provide enhanced functionality in areas discussed in this document.
Vertat, I.; Linhart, R.; Masopust, J.; Vobornik, A.; Dudacek, L.
Satellite attitude determination is a complex process with expensive hardware and software and it could consume the most of resources (volume, mass, electric power), especially of small satellites as CubeSats. Thermal radiation infrared detectors could be one of useful sensors for attitude determination systems in such small satellites. Nowadays, these sensors are widely used in contact-less thermometers and thermo-cameras resulting in a low-cost technology. On low Earth orbits the infrared thermal sensors can be utilized for coarse attitude determination against a relative warm and close Earth's globe.
Full Text Available The aerodynamic parameters of ducted fan micro aerial vehicles (MAVs are difficult and expensive to precisely measure and are, therefore, not available in most cases. Furthermore, the actuator dynamics with risks of potentially destabilizing the overall system are important but often neglected consideration factors in the control system design of ducted fan MAVs. This paper presents a near-hover adaptive attitude control strategy of a prototype ducted fan MAV with actuator dynamics and without any prior information about the behavior of the MAV. The proposed strategy consists of an online parameter estimation algorithm and an adaptive gain scheduling algorithm, with the former accommodating parametric uncertainties, and the latter approximately eliminating the coupling among axes and guaranteeing the control quality of the MAV. The effectiveness of the proposed strategy is verified numerically and experimentally.
CERN Neyrac Films
English version. Part of the series of films produced by CERN about the SPS. "More than 10.000 things to control, 7,00 things to measure and 30,000 ? to survey, distributed over more than 10 square km. That was the problem which faced the controls group." Comments: images of control room, computer screens, and computer centre rather dark
Hahne, Amina Katharina; Benndorf, Ralf; Frey, Peter; Herzig, Stefan
Curriculum-wide implementation of computer-based learning (CBL) in undergraduate medical education remains elusive. Unlike many pilot tests of singular learning programmes, dropout rates are high and acceptance seems low in the long run. We studied the effect of a new CBL programme, suitable for curriculum-wide implementation, on Year 3 medical students' attitudes towards CBL. Students from 2 universities participating in a mandatory pharmacology course were given access to a CBL programme covering cardiovascular drug therapy in a controlled randomised study (n = 167). Learner properties and attitude towards CBL were measured using psychometric scales, and knowledge by multiple-choice questions (pre- and post-test). Attitude towards CBL worsened in the CBL group (n = 70). Individual learners' properties did not explain this effect. The perceived programme quality was rated only 'average', which may contribute to the lower post-test values of attitude towards CBL. Learning outcomes were similar between the control group (n = 97) and students using CBL (n = 44). Learning efforts were shifted from self-study towards CBL. The initial enthusiasm of students was not maintained when using a programme designed to complement or even replace traditional teaching. Curriculum-wide implementation of CBL might be hampered by the discouragement of users.
Mahapatra, K.; Gustavsson, L. [Ecotechnology, Mid Sweden University, 831 25 Oestersund (Sweden)
Questionnaire surveys of Swedish homeowners of detached houses were carried out in 2004 and 2007 to understand their needs and attitudes towards attributes of innovative heating systems (IHSs) comprised of a bedrock heat pump, district heating, or a wood pellet boiler. In each occasion 1,500 homeowners were randomly selected. The response rate was 42% in 2004 and 48% in 2007. Results showed that the majority of the respondents were satisfied with their existing heating system and did not intend to install new systems. Economic factors and functional reliability were the most important factors in the respondents' choices of heating system, while environmental factors were of lower importance. Among the IHSs, respondents had the most favorable attitude towards bedrock heat pumps followed by district heating and pellet boilers. But the attitude was more favorable towards electric boilers than for pellet boilers. The least favorable attitude was towards oil boilers. Between 2004 and 2007, there was a positive change in respondents' attitude towards IHSs and electric boilers, and a negative change in attitude towards resistance heaters and oil boilers.
1. Explicit-Model-Based Fault Detection Method in Industrial Plants 2. Soft Sensor: An Effective Approach to Improve Control 3. Techniques in Soft Computing and Their Utilization in Mechatronic Products 4. Techniques in the Control of Interconnected Plants 5. A Mechatronic Systems Approach to Controlling Robotic Systems with Actuator Dynamics 6. Process and Control Design for Fast Coordinate Measuring Machines 7. Techniques in the Stability of Mechatronic Systems with Sensor or Actuator Failure.
Urbin, J.; /Fermilab
The DO cryogenic system is controlled by a TI565-PLC based control system. This allows the system to be unmanned when in steady state operation. System experts will need to be contacted when system parameters exceed normal operating points and reach alarm setpoints. The labwide FIRUS system provides one alarm monitor and communication link. An autodialer provides a second and more flexible alarm monitor and communication link. The autodialer monitors contact points in the control system and after receiving indication of an alarm accesses a list of experts which it calls until it receives an acknowledgement. There are several manufacturers and distributors of autodialer systems. This EN explains the search process the DO cryo group used to fmd an autodialer system that fit the cryo system's needs and includes information and specs for the unit we chose.
Rui Jiang; Gongliu Yang; Rui Zou; Jing Wang; Jing Li
In the dual-axis rotation inertial navigation system (INS), besides the gyro error, accelerometer error, rolling misalignment angle error, and the gimbal angle error, the shaft swing angle and the axis non-orthogonal angle also affect the attitude accuracy. Through the analysis of the structure, we can see that the shaft swing angle and axis non-orthogonal angle will produce coning errors which cause the fluctuation of the attitude. According to the analysis of the rotation vector, it can be ...
Danishevski, Kirill; Gilmore, Anna; McKee, Martin
Background Since the political transition in 1991, Russia has been targeted intensively by the transnational tobacco industry. Already high smoking rates among men have increased further; traditionally low rates among women have more than doubled. The tobacco companies have so far faced little opposition as they shape the discourse on smoking in Russia. This paper asks what ordinary Russians really think about possible actions to reduce smoking. Methods A representative sample of the Russian population (1600 respondents) was interviewed face-to-face in November 2007. Results Only 14% of respondents considered tobacco control in Russia adequate, while 37% felt that nothing was being done at all. There was support for prices keeping pace with or even exceeding inflation. Over 70% of all respondents favoured a ban on sales from street kiosks, while 56% believed that existing health warnings (currently 4% of front and back of packs) were inadequate. The current policy of designating a few tables in bars and restaurants as non-smoking was supported by less than 10% of respondents, while almost a third supported a total ban, with 44% supporting provision of equal space for smokers and non-smokers. Older age, non-smoking status and living a smaller town all emerged as significantly associated with the propensity to support of antismoking measures. The tobacco companies were generally viewed as behaving like most other companies in Russia, with three-quarters believing that they definitely or maybe bribe politicians. Knowledge of impact of smoking on health was limited with significant underestimation of dangers and addictive qualities of tobacco. A third believed that light cigarettes are safer than normal. Conclusion The majority of the Russian population would support considerable strengthening of tobacco control policies but there is also a need for effective public education campaigns. PMID:18653793
Full Text Available This lecture deals with the application problems of convertibility GPS system at paddle excavator K 800. The claims of the modern operating surface mining of the excavators requires a lot of information for monitoring of mining process, capacity mining, selective extraction etc. The utilization of monitoring the excavator setting by GPS system proved to be the only one proper because the receivers are resistant to the vibration, dust, temperature divergence and weather changeable. Only the direct contact with communications satellite is required. It means that they can´t be located in a metal construction space (shadow caused by construction elements, influence of electrical high voltage cables even they can´t be located close to the paddle wheel on the paddle boom (shadow possibility caused by cuttinng edge created during lower gangplanks mining. This is the reason that GPS receivers are set uppermost on the metal construction excavator and the mathematical formulation is required for determination of paddle wheel petting. The relations for calculation of the paddle wheel coordinate were defined mathematically and after that the mathematical model was composed.
Keywords. Iterative method; optimal control theory; diatomic systems; quantum control. Abstract. Controlling molecular energetics using laser pulses is exemplified for nuclear motion in two different diatomic systems. The problem of finding the optimized field for maximizing a desired quantum dynamical target is formulated ...
Redondo, Ignacio; Puelles, María
What is going on with environmental education, which is currently unable to promote pro-environmental behaviors as effectively as it promotes pro-environmental attitudes? A tentative answer is that the environmental attitude-behavior gap observed in some individuals is just one manifestation of their lack of self-control for maintaining…
He, Yuan; Zhang, Ning; Wang, Jue; He, Na; Du, Yan; Ding, Jing-Xin; Zhang, Ying; Li, Xiao-Tian; Huang, Jian; Hua, Ke-Qin
With increasing acceptance of premarital sex among young Chinese women, the rates of unintended pregnancies and induced abortions are becoming alarmingly high, suggesting the needs of educating women with adequate contraceptive knowledge and providing them with accessible contraceptive services. Previous studies have shown that knowledge and attitudes towards contraception could be modified through intervention strategies. This study aimed to evaluate the effects of two community intervention models on modifying contraceptive attitudes and behaviors among nulliparous women. In this clustered randomized controlled trial, nulliparous women aged 18-40 years from 18 communities were enrolled and randomized to either the traditional community intervention model (TC model) or the more comprehensive new community-based intervention model (NC model) with a ratio of 1:2. Contraceptive attitudes and behaviors were assessed before and after the interventions. A total of 901 nulliparous women were followed. The most common contraceptive method in both groups was condom (approximately 80%) before or after interventions. The rates of using effective contraceptive methods were very low (women held negative attitudes and behaviors towards effective contraceptive methods. The NC model, integrating existing health resources, had more positive influence than the TC model on the favorable contraceptive attitudes and behaviors towards the use of any contraceptive methods, but had limited impact on the use of effective contraceptive methods. Our study suggested the feasibility of applying the NC model in Shanghai. Interventions on contraceptive attitudes and behaviors should base on the existing health service system, synthesize resources and selectively apply to populations with distinct characteristics.
Colorado, J; Barrientos, A; Rossi, C; Parra, C
This paper presents a novel bat-like unmanned aerial vehicle inspired by the morphing-wing mechanism of bats. The goal of this paper is twofold. Firstly, a modelling framework is introduced for analysing how the robot should manoeuvre by means of changing wing morphology. This allows the definition of requirements for achieving forward and turning flight according to the kinematics of the wing modulation. Secondly, an attitude controller named backstepping+DAF is proposed. Motivated by biological evidence about the influence of wing inertia on the production of body accelerations, the attitude control law incorporates wing inertia information to produce desired roll (ϕ) and pitch (θ) acceleration commands (desired angular acceleration function (DAF)). This novel control approach is aimed at incrementing net body forces (F(net)) that generate propulsion. Simulations and wind-tunnel experimental results have shown an increase of about 23% in net body force production during the wingbeat cycle when the wings are modulated using the DAF as a part of the backstepping control law. Results also confirm accurate attitude tracking in spite of high external disturbances generated by aerodynamic loads at airspeeds up to 5 ms⁻¹.
Tsuda, Yuichi; Nakasuka, Shinichi
This paper describes a new control algorithm for achieving any arbitrary attitude and angular velocity states of a rigid body, even fast and complicated tumbling rotations, under some practical constraints. This technique is expected to be applied for the attitude motion synchronization to capture a non-cooperative, tumbling object in such missions as removal of debris from orbit, servicing broken-down satellites for repairing or inspection, rescue of manned vehicles, etc. For this objective, we have introduced a novel control algorithm called Free Motion Path Method (FMPM) in the previous paper, which was formulated as an open-loop controller. The next step of this consecutive work is to derive a closed-loop FMPM controller, and as the preliminary step toward the objective, this paper attempts to derive a conservative state variables representation of a rigid body dynamics. 6-Dimensional conservative state variables are introduced in place of general angular velocity-attitude angle representation, and how to convert between both representations are shown in this paper.
Jiang, Rui; Yang, Gongliu; Zou, Rui; Wang, Jing; Li, Jing
In the dual-axis rotation inertial navigation system (INS), besides the gyro error, accelerometer error, rolling misalignment angle error, and the gimbal angle error, the shaft swing angle and the axis non-orthogonal angle also affect the attitude accuracy. Through the analysis of the structure, we can see that the shaft swing angle and axis non-orthogonal angle will produce coning errors which cause the fluctuation of the attitude. According to the analysis of the rotation vector, it can be seen that the coning error will generate additional drift velocity along the rotating shaft, which can reduce the navigation precision of the system. In this paper, based on the establishment of the modulation average frame, the vector projection is carried out, and then the attitude conversion matrix and the attitude error matrix mainly including the shaft swing angle and axis non-orthogonal are obtained. Because the attitude angles are given under the static condition, the shaft swing angle and the axis non-orthogonal angle are estimated by the static Kalman filter (KF). This kind of KF method has been widely recognized as the standard optimal estimation tool for estimating the parameters such as coning angles (α₁ , α₂), initial phase angles (ϕ₁,ϕ₂), and the non-perpendicular angle (η). In order to carry out the system level verification, a dual axis rotation INS is designed. Through simulation and experiments, the results show that the amplitudes of the attitude angles' variation are reduced by about 20%-30% when the shaft rotates. The attitude error equation is reasonably simplified and the calibration method is accurate enough. The attitude accuracy is further improved.
Full Text Available In the dual-axis rotation inertial navigation system (INS, besides the gyro error, accelerometer error, rolling misalignment angle error, and the gimbal angle error, the shaft swing angle and the axis non-orthogonal angle also affect the attitude accuracy. Through the analysis of the structure, we can see that the shaft swing angle and axis non-orthogonal angle will produce coning errors which cause the fluctuation of the attitude. According to the analysis of the rotation vector, it can be seen that the coning error will generate additional drift velocity along the rotating shaft, which can reduce the navigation precision of the system. In this paper, based on the establishment of the modulation average frame, the vector projection is carried out, and then the attitude conversion matrix and the attitude error matrix mainly including the shaft swing angle and axis non-orthogonal are obtained. Because the attitude angles are given under the static condition, the shaft swing angle and the axis non-orthogonal angle are estimated by the static Kalman filter (KF. This kind of KF method has been widely recognized as the standard optimal estimation tool for estimating the parameters such as coning angles (α1 , α2, initial phase angles (ϕ1,ϕ2, and the non-perpendicular angle (η. In order to carry out the system level verification, a dual axis rotation INS is designed. Through simulation and experiments, the results show that the amplitudes of the attitude angles’ variation are reduced by about 20%–30% when the shaft rotates. The attitude error equation is reasonably simplified and the calibration method is accurate enough. The attitude accuracy is further improved.
Kelly, Betsy; And Others
Presents a brief summary of the functions of the Bibliographic Access & Control System (BACS) implemented at the Washington University School of Medicine Library, and outlines the design, development, and uses of the system. Bibliographic control of books and serials and user access to the system are also discussed. (Author/JL)
National Aeronautics and Space Administration — This data set contains the attitude data for the rotor of the Galileo spacecraft. The data provided are derived from the Attitude and Articulation Control System...
Engelhardt, Douglas B.; Mohan, Srinivas N.
The pitch and yaw attitude control thrusters of the Magellan spacecraft generate uncoupled moments about the spacecraft center of mass, perturbing the spacecraft's orbit. A strategy to model these perturbing forces in the spacecraft equations of motion is presented. This strategy can model the thruster forces occurring in the nominal and contingency modes of attitude control operation. In the nominal mode, the thrusters fire only to balance the daily unloading of the momentum wheels. The contingency case will occur if a pitch or yaw axis momentum wheel fails, and the thrusters could fire up to 1200 times around the orbit to replace the failed wheel's momentum contribution. Deterministic errors are computed and shown to be under specified error requirements.
M. Sait DINC
Full Text Available In the last decade, female entrepreneurship has been identified as one of the most important unutilised sources of economic growth. Entrepreneurial intention of women has become a key element in establishing a new business. The factors influencing entrepreneurial intention of women, particularly in developing countries, have attracted curiosity lot of attention. The purpose of the study is to examine the relationship between demographic variables, personal attitude, subjective norm, perceived behavioural control, and entrepreneurial intentions of women in Federation of Bosnia and Herzegovina. A total of 216 questionnaires were collected from women in two big cities in Bosnia: Tuzla and Sarajevo. Relationships between the variables were evaluated using factor analysis, reliability, correlations, descriptive statistics, and regression. The findings show a positive and significant influence of personal attitude and perceived behavioural control on entrepreneurial intention.
Mirkarimi, Kamal; Eri, Maryam; Ghanbari, Mohammad R; Kabir, Mohammad J; Raeisi, Mojtaba; Ozouni-Davaji, Rahman B; Aryaie, Mohammad; Charkazi, Abdurrahman
We were guided by the Protection Motivation Theory to test the motivational interviewing effects on attitude and intention of obese and overweight women to do regular physical activity. In a randomized controlled trial, we selected using convenience sampling 60 overweight and obese women attending health centres. The women were allocated to 2 groups of 30 receiving a standard weight-control programme or motivational interviewing. All constructs of the theory (perceived susceptibility, severity, self-efficacy and response efficacy) and all anthropometric characteristics (except body mass index) were significantly different between the groups at 3 study times. The strongest predictors of intention to do regular physical exercise were perceived response efficacy and attitude at 2- and 6-months follow-up. We showed that targeting motivational interviewing with an emphasis on Protection Motivation Theory constructs appeared to be beneficial for designing and developing appropriate intervention to improve physical activity status among women with overweight and obesity.
, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusser linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field......, nevertheless, a solution of the riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when satellite is on a near polar orbit is used throughout this paper. Three types of attitude controllers are proposed......Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvemant of micro-electronics. Required pointing accuracy of small, inexpensive satellites is often relatively loose, within a couple of degrees. Application of cheap...
Heffernan, C; Misturelli, F; Nielsen, L; Gunn, G J; Yu, J
At present, national-level policies concerning the eradication and control of bovine viral diarrhoea (BVD) differ widely across Europe. Some Scandinavian countries have enacted strong regulatory frameworks to eradicate the disease, whereas other countries have few formal policies. To examine these differences, the attitudes of stakeholders and policy makers in 17 European countries were investigated. A web-based questionnaire was sent to policy makers, government and private sector veterinarians, and representatives of farmers' organisations. In total, 131 individuals responded to the questionnaire and their responses were analysed by applying a method used in sociolinguistics: frame analysis. The results showed that the different attitudes of countries that applied compulsory or voluntary frameworks were associated with different views about the attribution or blame for BVD and the roles ascribed to farmers and other stakeholders in its eradication and control.
Eaves, Lindon J; Silberg, Judy L
The genetic and social causes of individual differences in attitudes to gun control are estimated in a sample of senior male and female twin pairs in the United States. Genetic and environmental parameters were estimated by weighted least squares applied to polychoric correlations for monozygotic (MZ) and dizygotic (DZ) twins of both sexes. The analysis suggests twin similarity for attitudes to gun control in men is entirely genetic while that in women is purely social. Although the volunteer sample is small, the analysis illustrates how the well-tested concepts and methods of genetic epidemiology may be a fertile resource for deepening our scientific understanding of biological and social pathways that affect individual risk to gun violence.
Author Affiliations. N Ananthkrishnan1 Rashi Bansal2. Head, CAE Analysis & Design Zeus Numerix Pvt Ltd. M-03, SINE, IIT Bombay Powai Mumbai 400076, India. MTech (Aerospace Engineering) with specialization in Dynamics & Control from IIT Bombay.
Hetel, Laurentiu; Daafouz, Jamal; Johansson, Karl
This edited monograph includes state-of-the-art contributions on continuous time dynamical networks with delays. The book is divided into four parts. The first part presents tools and methods for the analysis of time-delay systems with a particular attention on control problems of large scale or infinite-dimensional systems with delays. The second part of the book is dedicated to the use of time-delay models for the analysis and design of Networked Control Systems. The third part of the book focuses on the analysis and design of systems with asynchronous sampling intervals which occur in Networked Control Systems. The last part of the book exposes several contributions dealing with the design of cooperative control and observation laws for networked control systems. The target audience primarily comprises researchers and experts in the field of control theory, but the book may also be beneficial for graduate students. .
The Cassini Attitude and Articulation Control Subsystem (AACS) Flight Software (FSW) has achieved its intended design goals by successfully guiding and controlling the Cassini-Huygens planetary mission to Saturn and its moons. This paper describes an overview of AACS FSW details from early design, development, implementation, and test to its fruition of operating and maintaining spacecraft control over an eleven year prime mission. Starting from phases of FSW development, topics expand to FSW development methodology, achievements utilizing in-flight autonomy, and summarize lessons learned during flight operations which can be useful to FSW in current and future spacecraft missions.
Full Text Available The present paper addresses an attitude tracking control problem of a ducted fan microaerial vehicle. The proposed indirect adaptive controller can greatly reduce tracking error in the initial stage of the adaptive learning process by using an error compensation strategy and can achieve good capability to eliminate the adverse effect of measurement noises on the convergence of adjustable parameters. Moreover, the learning rate adaptation strategy is proposed to further minimize the adverse effect of large learning rates on the convergence of adjustable parameters. The experimental tests have illustrated the effectiveness of the proposed adaptive controller.
Escobar-Rodriguez, Tomas; Bartual-Sopena, Lourdes
Enterprise resources planning (ERP) systems enable central and integrative control over all processes throughout an organisation by ensuring one data entry point and the use of a common database. T his paper analyses the attitude of healthcare personnel towards the use of an ERP system in a Spanish public hospital, identifying influencing factors. This research is based on a regression analysis of latent variables using the optimisation technique of partial least squares. We propose a research model including possible relationships among different constructs using the technology acceptance model. Our results show that the personal characteristics of potential users are key factors in explaining attitude towards using ERP systems.
Jahanbakhsh, Maryam; Karimi, Saeed; Hassanzadeh, Akbar; Beigi, Maliheh
Electronic medical record system (EMRS) is a valuable system for safe access to the patient's data and increases health care quality. Manpower is one of the requirements for EMRS, among which manager is the most important person in any hospital. Taking into account manager's positive attitude and good commitments, EMRS will be implemented successfully. As such, we decided to assess manager's attitude and commitment toward EMRS in Isfahan hospitals in the year of 2014. This article aimed to determine the hospital managers' attitude and commitment toward the implementation of EMRS. The present article is an applied analytic study. Research society consisted of the managers of all the hospitals in Isfahan that include hospitals affiliated to Isfahan University of Medical Sciences, private, and social security hospitals. This study was done in 2014. Data collection tools included a questionnaire for which reliability and validity were determined. Data were analyzed by means of SPSS 20. Average score for the managers' attitude toward EMRS in the city of Isfahan was 77.5 out of 100 and their average score for commitment was 74.7. Manager's attitude in social security hospitals was more positive than the private and governmental ones (83.3%). In addition, the amount of commitment by the managers in social security hospitals was higher than the same in private and governmental hospitals (86.6%). At present, managers' attitude and commitment in Isfahan hospitals toward EMRS are very high and social security hospitals show more readiness in this respect.
Ambrose, Maureen; Hess, Ronald L.; Ganesan, Shankar
Research in organizational justice has always been interested in the relationship between justice and attitudes. This research often examines how different types of justice affect different attitudes, with distributive justice predicted to affect attitudes about specific events (e.g., performance evaluation) and procedural justice predicted to…
S. V. Маrtseva
Full Text Available The paper considers methodology for formation of product cost while applying «direct-costing» system. It has been shown that the application of the given system permits economically to justify and accurately to determine financial results of an enterprise activity which is planned for the future.
Rubio, Francisco; Bencomo, Sebastián
This book sheds light on networked control systems; it describes different techniques for asynchronous control, moving away from the periodic actions of classical control, replacing them with state-based decisions and reducing the frequency with which communication between subsystems is required. The text focuses specially on event-based control. Split into two parts, Asynchronous Control for Networked Systems begins by addressing the problems of single-loop networked control systems, laying out various solutions which include two alternative model-based control schemes (anticipatory and predictive) and the use of H2/H∞ robust control to deal with network delays and packet losses. Results on self-triggering and send-on-delta sampling are presented to reduce the need for feedback in the loop. In Part II, the authors present solutions for distributed estimation and control. They deal first with reliable networks and then extend their results to scenarios in which delays and packet losses may occur. The novel ...
SPACECRAFT, *TELEMETER SYSTEMS), DATA TRANSMISSION SYSTEMS , SOUNDING ROCKETS, BALLOONS, SATELLITE TRACKING SYSTEMS, DATA STORAGE SYSTEMS, SOLAR RADIATION, RADIOMETERS, ULTRAHIGH FREQUENCY, FLIGHT TESTING
Full Text Available Abstract Background The study examined the extent to which components based on a modified version of the theory of planned behavior explained employee participation in a new clinical office program designed to reduce patient waiting times in primary care clinics. Methods We regressed extent of employee participation on attitudes about the program, group norms, and perceived behavioral control along with individual and clinic characteristics using a hierarchical linear mixed model. Results Perceived group norms were one of the best predictors of employee participation. Attitudes about the program were also significant, but to a lesser degree. Behavioral control, however, was not a significant predictor. Respondents with at least one year of clinic tenure, or who were team leaders, first line supervisor, or managers had greater participation rates. Analysis at the clinic level indicated clinics with scores in the highest quartile clinic scores on group norms, attitudes, and behavioral control scores were significantly higher on levels of overall participation than clinics in the lowest quartile. Conclusion Findings suggest that establishing strong norms and values may influence employee participation in a change program in a group setting. Supervisory level was also significant with greater responsibility being associated with greater participation.
Burgos, Estrella [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
Almost two third of the electric power generation in Mexico are obtained from hydrocarbons, for that reasons Comision Federal de Electricidad (CFE) dedicated special commitment in modernizing the operation of fossil fuel central stations. In attaining this objective the control systems play a fundamental roll, from them depend a good share of the reliability and the efficiency of the electric power generation process, as well as the extension of the equipment useful life. Since 1984 the Instituto de Investigaciones Electricas (IIE) has been working, upon the request of CFE, on the development of digital control systems. To date it has designed and implemented a logic control system for gas burners, which controls 32 burners of the Unit 4 boiler of the Generation Central of Valle de Mexico and two systems for distributed control for two combined cycle central stations, which are: Dos Bocas, Veracruz Combined cycle central, and Gomez Palacio, Durango combined cycle central. With these two developments the IIE enters the World tendency of implementing distributed control systems for the fossil fuel power central update [Espanol] Casi las dos terceras partes de la generacion electrica en Mexico se obtienen a partir de hidrocarburos, es por eso que la Comision Federal de Electricidad (CFE) puso especial empeno en modernizar la operacion de las centrales termoelectricas de combustibles fosiles. En el logro de este objetivo los sistemas de control desempenan un papel fundamental, de ellos depende una buena parte la confiabilidad y la eficiencia en el proceso de generacion de energia electrica, asi como la prolongacion de la vida util de los equipos. Desde 1984 el Instituto de Investigaciones Electricas (IIE) ha trabajado, a solicitud de la CFE, en el desarrollo de sistemas digitales de control. A la fecha se han disenado e implantado un sistema de control logico de quemadores de gas, el cual controla 32 quemadores de la caldera de la unidad 4 de la central de generacion
The Ground Control System contributes to the safe construction and operation of the subsurface facility, including accesses and waste emplacement drifts, by maintaining the configuration and stability of the openings during construction, development, emplacement, and caretaker modes for the duration of preclosure repository life. The Ground Control System consists of ground support structures installed within the subsurface excavated openings, any reinforcement made to the rock surrounding the opening, and inverts if designed as an integral part of the system. The Ground Control System maintains stability for the range of geologic conditions expected at the repository and for all expected loading conditions, including in situ rock, construction, operation, thermal, and seismic loads. The system maintains the size and geometry of operating envelopes for all openings, including alcoves, accesses, and emplacement drifts. The system provides for the installation and operation of sensors and equipment for any required inspection and monitoring. In addition, the Ground Control System provides protection against rockfall for all subsurface personnel, equipment, and the engineered barrier system, including the waste package during the preclosure period. The Ground Control System uses materials that are sufficiently maintainable and that retain the necessary engineering properties for the anticipated conditions of the preclosure service life. These materials are also compatible with postclosure waste isolation performance requirements of the repository. The Ground Control System interfaces with the Subsurface Facility System for operating envelopes, drift orientation, and excavated opening dimensions, Emplacement Drift System for material compatibility, Monitored Geologic Repository Operations Monitoring and Control System for ground control instrument readings, Waste Emplacement/Retrieval System to support waste emplacement operations, and the Subsurface Excavation System
Riemondy, Susan; Gonzalez, Lorie; Gosik, Kirk; Ricords, Amy; Schirm, Victoria
Patient-controlled analgesia (PCA) administered intravenously is a generally well-accepted therapy by nurses and patients. PCA devices are now available for oral medications, allowing patients to self-administer pain pills without requesting them from the nurse. Successful introduction of new pain medication delivery devices can depend on nurses' knowledge and attitudes. The aim of this institutional review board approved project was to evaluate nurses' perceptions and attitudes toward using an oral PCA device for patients' pain. A 4-week study was designed and conducted at an academic medical center on an orthopedic unit and a women's health unit. Nurse participants received education on using the oral PCA device and were invited to complete a pre- and poststudy knowledge and attitude survey regarding pain management. Nurses and patients also completed a questionnaire about perceptions related to using the oral PCA device. Findings showed that nurses' attitudes toward using the oral PCA device were less favorable than those of patients, suggesting that nurses may require additional education for acceptance of this device. Results from 37 nurses showed improvement in overall knowledge and attitudes, from 70.8% pretest to 74.2% post-test. Although improvement was not statistically significant (p = .1637), two items showed significant improvement. Knowledge about the effectiveness of NSAIDS was 27.5% pretest compared with 60.0% post-test (p = .0028); and understanding about use of opioids in patients with a history of substance abuse was 50% pretest compared with 70% post-test (p = .0531). Helping nurses overcome the perceived barriers to use of an oral PCA device has potential implications for better pain management as well as enhanced patient satisfaction. Copyright © 2016 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.
on the accelerator pedal so that the speed of the vehicle is ... the vehicle. Sometimes, we use the word output for the effect. Thus, we assume that if an input is applied there will be a unique response. This relationship between the input and the output is .... frequency regulation, boiler control for steam generation, electric.
Full Text Available It is very important for drivers to obtain driving information easily and efficiently. There are many advanced devices used for driving safety assistance. Of these assistance devices, the head-up display (HUD system can promote the reduction of driver's reaction time and improve spatial awareness. The drivers' attitude towards and preference for HUD system are crucial to design the functional framework and interface of HUD system. This study explored the relationships between drivers' attitude and HUD presentation image designs using stated preference data from questionnaire survey. The questionnaire included drivers' attitude towards the use of HUD and the preference for the information display zone and information display elements of the HUD. Contrastive analysis was adopted to examine the variations in drivers' attitude and preference for age and driving skills. According to the results, the participants have varying attitudes to HUD system, but most participants show relatively unified preference for the information display zone and information display elements. The results can also be used to customize a HUD presentation image which is in accordance with the drivers' feelings and preferences.
Solanki, Jayesh Dalpatbhai; Sheth, Nidhi Shaileshbhai; Shah, Chinmay J; Mehta, Hemant B
Type 2 diabetes is the modern epidemic wherein patient care needs multiple approaches, education, and self-awareness being one of them. There are some knowledge, attitude, and practice (KAP) studies from India but very few relating it with disease control. We tried to study KAP of treated type 2 diabetics and its correlation with glycemic control. Cross-sectional KAP study. We formulated KAP questionnaires in the form of KAP - 10 points for each and total 30. We recruited 200 type 2 diabetics (96 males, 104 females) treated by MD physicians with known current glycemic status. They were asked KAP questionnaires one to one by a direct interview in local language and results were associated with various factors and glycemic control. KAP score on was average 19 out of 30 in type 2 diabetics having mean age 58 years, mean duration 9 years. KAP score was unaffected by gender, occupation, duration of disease but significantly affected by current age, and education level. Only 40% patients had good glycemic control who scored better KAP than poor glycemic. There was positive correlation between KAP score and glycemic control, with significance for only glycosylated hemoglobin and not fasting blood sugar, postprandial blood sugar. Physician treated type 2 diabetics of our region had moderate KAP score, affected by age, education which suggested to affect glycemic control. Lacunae in knowledge regarding incurability of disease, attitudes toward complication, self-care, and good practices like walking, enriching knowledge need improvement so as an optimum glycemic control.
Full Text Available María Y Makuch,1 Maria José D Osis,1 Karla Simonia de Pádua,1,2 Luis Bahamondes3 1Center for Research in Reproductive Health (CEMICAMP, 2Prof Dr José Aristodemo Pinotti Women's Hospital, University of Campinas, 3Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, and National Institute of Hormones and Women's Health, Campinas, São Paulo, Brazil Background: The purpose of this study was to assess the attitudes and prescribing practices of Brazilian obstetricians and gynecologists regarding use of contraceptive methods to interfere with menstruation and/or induce amenorrhea. Methods: We undertook a nationwide survey of Brazilian obstetricians and gynecologists selected using a computer-generated randomization system. Participants completed a questionnaire on prescription of contraceptives and extended/continuous regimens of combined oral contraceptives (COCs. Results: In total, 79.2% of Brazilian obstetricians and gynecologists reported that 20%–40% of their patients consulted them for menstrual-related complaints and 26%–34% of the gynecologists reported that 21%–40% of their patients consulted them for reduction in the intensity, frequency, and/or duration of menstrual bleeding. Overall, 93% stated that medically induced amenorrhea represents no risk to women's health and 82.5% said that they prescribed contraceptives to control menstruation or induce amenorrhea. The contraceptives most commonly prescribed were extended-cycle 24/4 or 26/2 COC regimens and the levonorgestrel-releasing intrauterine system. Poisson regression analysis showed that Brazilian obstetricians and gynecologists prescribing contraceptives to control menstruation or induce amenorrhea consider extended-use or continuous-use COC regimens to be effective for both indications (prevalence ratio 1.23 [95% confidence interval 1.09–1.40] and prevalence ratio 1.28 [95% confidence interval 1.13–1.46], respectively. They also
The focus of this qualitative case study is on an attitudinal change of teachers towards teacher evaluation with the implementation of a new evaluation system. The goal of this qualitative case study was to gain an understanding of how the implementation of the new New Jersey teacher evaluation system relates to teachers' attitudes toward…
Full Text Available We consider two classes of restricted H systems, both dealing with numbers associated to the terms of splicing operations. In one of them, these numbers indicate the age of the strings (the generation when the strings are produced, in the second one the numbers can be interpreted as valences of the strings. Restricting the splicing to strings of "a similar age", or accepting as complete splicing processes only those processes which produce strings with a null valence increase the generative power of H systems (with finite sets of rules.
Jurdjevic, V.; Sussmann, H. J.
The controllability properties of systems which are described by an evolution equation in a Lie group are studied. The revelant Lie algebras induced by a right invariant system are singled out, and the basic properties of attainable sets are derived. The homogeneous case and the general case are studied, and results are interpreted in terms of controllability. Five examples are given.
Full Text Available Although the use of placebo in clinical trials of schizophrenia patients is controversial because of medical and ethical concerns, placebo-controlled clinical trials are commonly used in the licensing of new drugs.The objective of this study was to assess the attitudes toward placebo-controlled clinical trials among patients with schizophrenia in Japan.Using a cross-sectional design, we recruited patients (n = 251 aged 47.7±13.2 (mean±SD with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder who were admitted to six psychiatric hospitals from December 2013 to March 2014. We employed a 14-item questionnaire specifically developed to survey patients' attitudes toward placebo-controlled clinical trials.The results indicated that 33% of the patients would be willing to participate in a placebo-controlled clinical trial. Expectations for improvement of disease, a guarantee of hospital treatment continuation, and encouragement by family or friends were associated with the willingness to participate in such trials, whereas a belief of additional time required for medical examinations was associated with non-participation.Fewer than half of the respondents stated that they would be willing to participate in placebo-controlled clinical trials. Therefore, interpreting the results from placebo-controlled clinical trials could be negatively affected by selection bias.
optimal control theory (OCT)3–8 to design the pulse shapes have met with considerable theoretical and experimental success for small molecular systems. These include control over branching processes such as dissociation vs. ionization in HCl, HF, HI, CO, and ICN demonstrated by several groups,9–12 laser control of ...
Full Text Available In the present work, we consider a class of nonlinear optimal control problems, which can be called “optimal control problems in mechanics.” We deal with control systems whose dynamics can be described by a system of Euler-Lagrange or Hamilton equations. Using the variational structure of the solution of the corresponding boundary-value problems, we reduce the initial optimal control problem to an auxiliary problem of multiobjective programming. This technique makes it possible to apply some consistent numerical approximations of a multiobjective optimization problem to the initial optimal control problem. For solving the auxiliary problem, we propose an implementable numerical algorithm.
Full Text Available Hexapod is a testing device for generation of six degrees of freedom movement. Its control system is built from the National Instruments components and control application is created in the software LabVIEW. Using the real-time system to run this application requires special programming procedures because the precise timing of the control loop has to be observed. The hexapod motion control is based on its kinematic model. Equations for the six basic motions (3-axis movement and 3-axis rotation were obtained from the kinematic model. These equations are implemented directly in the control program for basic movement and rotation control. The control system, program design and program optimization are described in this paper.
Full Text Available Data packet dropout is a special kind of time delay problem. In this paper, predictive controllers for networked control systems (NCSs with dual-network are designed by model predictive control method. The contributions are as follows. (1 The predictive control problem of the dual-network is considered. (2 The predictive performance of the dual-network is evaluated. (3 Compared to the popular networked control systems, the optimal controller of the new NCSs with data packets dropout is designed, which can minimize infinite performance index at each sampling time and guarantee the closed-loop system stability. Finally, the simulation results show the feasibility and effectiveness of the controllers designed.
Siljak, Dragoslav D
Complex systems require fast control action in response to local input, and perturbations dictate the use of decentralized information and control structures. This much-cited reference book explores the approaches to synthesizing control laws under decentralized information structure constraints.Starting with a graph-theoretic framework for structural modeling of complex systems, the text presents results related to robust stabilization via decentralized state feedback. Subsequent chapters explore optimization, output feedback, the manipulative power of graphs, overlapping decompositions and t
Balbay, R.; Öz, G. K.; Arslan, Ö.; Özeren, F. F.; Küçük, İ.
A 13 meters former NATO radar is being converted into a radio telescope. The radio telescope is controlled by a system which has been developed at UZAYBİMER. The Telescope Control System(TCS) has been designed using modern industrial systems. TCS has been developed in LabView platform in which works Windows embedded OS. The position feedback used on radio telescopes is an industrial EtherCAT standard. ASCOM library is used for astronomical calculations.
Sekita, Toshiaki; Takeuchi, Syuhei; Minakuchi, Syunsuke
The aim of this study was to assemble and verify a measuring system for 3-D movements (attitude angle) of the denture during function. For the calibration test, the sensor was fixed at the center of the rotary table. Operation and stopping of the rotary table were repeated 8 times, and the direction of rotation was reversed in the middle. The amount of rotation was 1.2 and 2.4°. As a pilot clinical trial, the attitude angles of three upper complete dentures during tapping were measured by this system. The attitude angles calculated by this system reduced by 3-4%. Pitch and roll of Subject III were significantly larger than Subjects I and II (Pmeasurement accuracy of this system was equivalent to that of 3-D motion capture system by four infrared TV cameras. The measuring system using the IMU is reliable and easy to analyze the attitude angle of the denture during function. It may serve a diagnostic appliance to evaluate the quality of the denture. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.
Yan, Ruidong; Wu, Zhong
To achieve the high-precision attitude stabilization for the flexible spacecraft in the presence of space environmental disturbances, unmodeled dynamics, and the disturbances caused by the elastic vibration of flexible appendages, an extended disturbance observer (EDO) based controller is proposed. The proposed controller is formulated by combining EDO and a backstepping feedback controller. EDO is used to estimate the disturbance, which is modeled as an unknown high-order differentiable equation and the rth-order derivative of the disturbance is assumed to be bounded. Compared to the conventional first-order disturbance observer, the higher order EDO offers improvement in estimate accuracy, if the absolute values of poles for EDO transfer function are chosen larger than the frequency content of the disturbance. Then, the output of EDO plus the backstepping feedback controller are applied to stabilize the attitude with high precision by rejecting disturbances for the flexible spacecraft. Finally, numerical simulations have been conducted to verify the effectiveness of the proposed controller.
Name, Name; Mohamadian, Robab; Rahmani, Azad; Fizollah-Zadeh, Hussein; Jabarzadeh, Franak; Azadi, Arman; Rostami, Hussein
Many cancer patients still experience pain worldwide. There are many barriers for effective control of cancer pain and many of these are related to health care providers. There is a need for further investigation of these barriers. The aim of this study was to investigate nurse-related barriers to control of cancer pain among Iranian nurses. In this descriptive study 49 nurses from two hospitals affiliated to Tabriz and Ardebil Universities of Medical Sciences participated using a census sampling method. A demographic and profession related checklist and Barriers Questionnaire II (BQ-II) were used for data collection. The results showed negative attitudes of participants regarding control of cancer pain. Participants believed that cancer pain medications do not manage cancer pain at acceptable levels; patients may become addicted by using these drugs; cancer pain medications have many uncontrollable effects; and controlling cancer pain may distract the physicians from treating disease. Iranian nurses have negative attitudes toward pain control in cancer patients especially about effectiveness of pain medication and their side effects. Educational intervention to reduce these misconceptions is needed.
Kort-Butler, Lisa A; Sittner Hartshorn, Kelley J
Research demonstrates a complex relationship between television viewing and fear of crime. Social critics assert that media depictions perpetuate the dominant cultural ideology about crime and criminal justice. This article examines whether program type differentially affects fear of crime and perceptions of the crime rate. Next, it tests whether such programming differentially affects viewers' attitudes about the criminal justice system, and if these relationships are mediated by fear. Results indicated that fear mediated the relationship between viewing nonfictional shows and lack of support for the justice system. Viewing crime dramas predicted support for the death penalty, but this relationship was not mediated by fear. News viewership was unrelated to either fear or attitudes. The results support the idea that program type matters when it comes to understanding people's fear of crime and their attitudes about criminal justice.
As part of the RICIS activity, the reinforcement learning techniques developed at Ames Research Center are being applied to proximity and docking operations using the Shuttle and Solar Max satellite simulation. This activity is carried out in the software technology laboratory utilizing the Orbital Operations Simulator (OOS). This report is deliverable D2 Altitude Control Results and provides the status of the project after four months of activities and outlines the future plans. In section 2 we describe the Fuzzy-Learner system for the attitude control functions. In section 3, we provide the description of test cases and results in a chronological order. In section 4, we have summarized our results and conclusions. Our future plans and recommendations are provided in section 5.
Camacho, Eduardo F; Rubio, Francisco R; Martínez, Diego
Control of Solar Energy Systems details the main solar energy systems, problems involved with their control, and how control systems can help in increasing their efficiency. After a brief introduction to the fundamental concepts associated with the use of solar energy in both photovoltaic and thermal plants, specific issues related to control of solar systems are embarked upon. Thermal energy systems are then explored in depth, as well as other solar energy applications such as solar furnaces and solar refrigeration systems. Problems of variable generation profile and of the contribution of many solar plants to the same grid system are considered with the necessary integrated and supervisory control solutions being discussed. The text includes material on: · A comparison of basic and advanced control methods for parabolic troughs from PID to nonlinear model-based control; · solar towers and solar tracking; · heliostat calibration, characterization and off...
Full Text Available The purpose of this research is to evaluate the control of information system savings in the banking and to identify the weaknesses and problem happened in those saving systems. Research method used are book studies by collecting data and information needed and field studies by interview, observation, questioner, and checklist using COBIT method as a standard to assess the information system control of the company. The expected result about the evaluation result that show in the problem happened and recommendation given as the evaluation report and to give a view about the control done by the company. Conclusion took from this research that this banking company has met standards although some weaknesses still exists in the system.Index Terms - Control Information System, Savings
Marini, Sana Daya; Hasman, Arie; Huijer, Huda Abu-Saad; Dimassi, Hani
This study determines nurses' attitudes toward bar-coding medication administration system use. Some of the factors underlying the successful use of bar-coding medication administration systems that are viewed as a connotative indicator of users' attitudes were used to gather data that describe the attitudinal basis for system adoption and use decisions in terms of subjective satisfaction. Only 67 nurses in the United States had the chance to respond to the e-questionnaire posted on the CARING list server for the months of June and July 2007. Participants rated their satisfaction with bar-coding medication administration system use based on system functionality, usability, and its positive/negative impact on the nursing practice. Results showed, to some extent, positive attitude, but the image profile draws attention to nurses' concerns for improving certain system characteristics. The high bar-coding medication administration system skills revealed a more negative perception of the system by the nursing staff. The reasons underlying dissatisfaction with bar-coding medication administration use by skillful users are an important source of knowledge that can be helpful for system development as well as system deployment. As a result, strengthening bar-coding medication administration system usability by magnifying its ability to eliminate medication errors and the contributing factors, maximizing system functionality by ascertaining its power as an extra eye in the medication administration process, and impacting the clinical nursing practice positively by being helpful to nurses, speeding up the medication administration process, and being user-friendly can offer a congenial settings for establishing positive attitude toward system use, which in turn leads to successful bar-coding medication administration system use.
Bissontz, Jay E.
A motor vehicle electrical power distribution system includes a plurality of distribution sub-systems, an electrical power storage sub-system and a plurality of switching devices for selective connection of elements of and loads on the power distribution system to the electrical power storage sub-system. A state transition initiator provides inputs to control system operation of switching devices to change the states of the power distribution system. The state transition initiator has a plurality of positions selection of which can initiate a state transition. The state transition initiator can emulate a four position rotary ignition switch. Fail safe power cutoff switches provide high voltage switching device protection.
Magliano, Lorenza; Rinaldi, Angela; Costanzo, Regina; De Leo, Renata; Schioppa, Giustina; Petrillo, Miriam; Read, John
Despite scientific evidence that the majority of people with schizophrenia (PWS) have personal histories of traumatic life events and adversities, their needs for psychological support often remain unmet. Poor availability of nonpharmacological therapies in schizophrenia may be partly because of professionals' attitudes toward people diagnosed with this disorder. As future health professionals, psychology students represent a target population for efforts to increase the probability that PWS will be offered effective psychological therapies. This quasi-randomized controlled study investigated the effect of an educational intervention, addressing common prejudices via scientific evidence and prerecorded audio-testimony from PWS, on the attitudes of psychology students toward PWS. Students in their fifth year of a master's degree in Psychology at the Second University of Naples, Italy were randomly assigned to an experimental group-which attended two 3-hr sessions a week apart-or to a control group. Compared with their baseline assessment, at 1-month reassessment the 76 educated students endorsed more psychosocial causes and more of them recommended psychologists in the treatment of schizophrenia. They were also more optimistic about recovery, less convinced that PWS are recognizable and unpredictable, and more convinced that treatments, pharmacological and psychological, are useful. No significant changes were found, from baseline to 1-month reassessment, in the 112 controls. At 1-month reassessment, educated students were more optimistic about recovery and less convinced that PWS are unpredictable than controls. These findings suggest that psychology students' attitudes toward PWS can be improved by training initiatives including education and indirect contact with users. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Peñas Lledó, E; Sancho, L; Waller, G
This study of non-clinical adolescent males and females examined associations of objectively measured physical characteristics with greater use of methods of weight control and considered whether the relationships between these variables might be explained by a mediating effect of a subjective characteristic--unhealthy eating attitudes. Non-clinical male and female adolescents completed measures of weight control and eating attitudes, and their physical characteristics were measured using a range of standardized anthropometry techniques. Regression analyses were used to test the role of eating attitudes as mediators in the relationship between physical characteristics and the use of weight control methods. The data were compatible with a partial mediator model, where physical characteristics influence eating attitudes, and those where attitudes drive the use of methods to control weight. However, not all of the relationship was explained by this mediator. In addition, there were different patterns of association for men and women, consistent with different patterns of bodily focus between the genders. These findings stress the importance of understanding objective physical characteristics as well as subjective eating attitudes to find out why people use different levels of weight control behaviours. Limitations, further research and potential implications for clinical and preventative programmes are discussed.
Montel, J.; Andre, Y.; Mirc, F.; Etcheto, P.; Evrard, J.; Bray, N.; Saccoccio, M.; Tomasini, L.; Perot, E.
ESTADIUS is an autonomous, accurate and daytime attitude estimation system, for stratospheric balloons that require a high level of attitude measurement and stability. The system has been developed by CNES. ESTADIUS is based on star sensor an pyrometer data fusion within an extended Kalman filter. The star sensor is composed of a 16 MPixels visible-CCD camera and a large aperture camera lens (focal length of 135mm, aperture f/1.8, 10ºx15º field of view or FOV) which provides very accurate stars measurements due to very low pixel angular size. This also allows detecting stars against a bright sky background. The pyrometer is a 0.01º/h performance class Fiber Optic Gyroscope (FOG). The system is adapted to work down to an altitude of ~25km, even under high cinematic conditions. Key elements of ESTADIUS are: daytime conditions use (as well as night time), autonomy (automatic recognition of constellations), high angular rate robustness (a few deg/s thanks to the high performance of attitude propagation), stray-light robustness (thanks to a high performance baffle), high accuracy (CIDRE will use the system ESTADIUS is probably the first autonomous, large FOV, daytime stellar attitude measurement system. This paper details the technical features and in-flight results.
Full Text Available Traction control is a widely used control system to increase stability and safety of four wheel vehicles. Automatic stability control is used in the BMW K1200R motorcycle and in motoGP competition, but not in other motorcycles. This paper presents an algorithm and a low-cost real-time hardware implementation for motorcycles. A prototype has been developed, applied on a commercial motorcycle, and tested in a real track. The control system that can be tuned by the driver during the race has been appreciated by the test driver.
Cogin, Julie Ann; Ng, Ju Li; Lee, Ilro
We assess how human resource management (HRM) is implemented in Australian hospitals. Drawing on role theory, we consider the influence HRM has on job attitudes of healthcare staff and hospital operational efficiency. We adopt a qualitative research design across professional groups (physicians, nurses, and allied health staff) at multiple levels (executive, healthcare managers, and employee). A total of 34 interviews were carried out and analyzed using NVivo. Findings revealed a predominance of a control-based approach to people management. Using Snell's control framework (AMJ 35:292-327, 1992), we found that behavioral control was the principal form of control used to manage nurses, allied health workers, and junior doctors. We found a mix between behavior, output, and input controls as well as elements of commitment-based HRM to manage senior physicians. We observed low levels of investment in people and a concentration on transactional human resource (HR) activities which led to negative job attitudes such as low morale and frustration among healthcare professionals. While hospitals used rules to promote conformity with established procedures, the overuse and at times inappropriate use of behavior controls restricted healthcare managers' ability to motivate and engage their staff. Excessive use of behavior control helped to realize short-term cost-cutting goals; however, this often led to operational inefficiencies. We suggest that hospitals reduce the profusion of behavior control and increase levels of input and output controls in the management of people. Poor perceptions of HR specialists and HR activities have resulted in HR being overlooked as a vehicle to address the strategic challenges required of health reform and to build an engaged workforce.
The goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mission is to expand understanding of high-energy astrophysical processes and sources, in support of NASA's first science objective in Astrophysics: "Discover how the universe works." X-ray polarimetry is the focus of the IXPE science mission. Polarimetry uniquely probes physical anisotropies-ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin-that are not otherwise measurable. The IXPE Observatory consists of Spacecraft and Payload modules. The Payload includes three polarization sensitive, X-ray detector units (DU), each paired with its corresponding grazing incidence mirror module assemblies (MMA). A deployable boom provides the correct separation (focal length) between the DUs and MMAs. These Payload elements are supported by the IXPE Spacecraft. A star tracker is mounted directly with the deployed Payload to minimize alignment errors between the star tracker line of sight (LoS) and Payload LoS. Stringent pointing requirements coupled with a flexible structure and a non-collocated attitude sensor-actuator configuration requires a thorough analysis of control-structure interactions. A non-minimum phase notch filter supports robust control loop stability margins. This paper summarizes the IXPE mission science objectives and Observatory concepts, and then it describes IXPE attitude determination and control implementation. IXPE LoS pointing accuracy, control loop stability, and angular momentum management are discussed.
Gross, Fabian; Geiger, Mark; Buck, Reiner
This paper describes the development of a universal heliostat control system as part of the AutoR project . The system can control multiple receivers and heliostat types in a single application. The system offers support for multiple operators on different machines and is designed to be as adaptive as possible. Thus, the system can be used for different heliostat field setups with only minor adaptations of the system's source code. This is achieved by extensive usage of modern programming techniques like reflection and dependency injection. Furthermore, the system features co-simulation of a ray tracer, a reference PID-controller implementation for open volumetric receivers and methods for heliostat calibration and monitoring.
Today the Linux operating system has become a real alternative for industrial control systems. Linux supports all layers in control systems starting with Real-Time or embedded systems for data acquisition, following with treatment, storage, communication and data adaptation, and finally, with supervision and user interfaces. In the last years the Linux development has grown being incorporated in several industrial systems demonstrating high performance, availability and stability for complex processes in chemical, automobile or petrol industries. In many of these industries Linux architectures have been tested and validated successfully. The new CERN policy supporting Linux, as well as the emergence of cheap and robust Linux solutions, motivates its implementation in our safety control and supervision systems in the near future.
Afsari, Atousa; Mirghafourvand, Mojgan; Valizadeh, Sousan; Abbasnezhadeh, Massomeh; Galshi, Mina; Fatahi, Samira
The attitude of a girl toward her menstruation and puberty has a considerable impact on her role during motherhood, social adjustment, and future marital life. This study was conducted in 2014 with the aim of comparing the effects of educating mothers and girls on the attitudes of adolescent girls of Tabriz City, Iran, towards puberty health. This randomized control clinical trial was conducted on 364 adolescent girls who experienced menstruation. Twelve schools were selected randomly among 107 secondary schools for girls. One-third of the students of each school were selected randomly using a table of random numbers and socio-demographic and each participant was asked to answer the attitude questionnaires. The schools were randomly allocated to the groups of mother's education, girl's education, and no-intervention. The attitude questionnaire was filled out by the participants again 2 months after intervention. The general linear model, in which the baseline values were controlled, was employed to compare the scores of the three groups after the intervention. No significant differences were observed among the three groups in terms of the attitude score before intervention (p>0.05). Attitude score improvement after intervention in the girl's education group was significantly higher than the one of both mother's education (adjusted mean difference [AMD]: 1.8; [95% confidence interval (CI): 0.4-1.3]) and no-intervention groups (AMD: 1.3; [95% CI: 0.0-2.6]) by controlling the attitude score before intervention. Based on the findings, it is more effective to educate girls directly about puberty health to improve adolescent girls' attitudes than educating mothers and asking them to transfer information to the girls. Nevertheless, studies with longer training period and follow-up are proposed to determine the effects of educating girls (through their mothers) on their attitudes about puberty health.
Liu, Chang; Prior, Stephen D.
This paper presents the design of quadrotor control architecture, based on crowd-sourcing electronics. The aim of this quadrotor is to provide a test-bed for vision-based autonomous navigation system in GPS denied environments. The control architecture consists of a cascaded structure, where an attitude controller nested in velocity and altitude controllers. The sub-controllers are all linear controllers with feedforward term to linearize the quadrotor dynamics. The control and sensor fusion ...
The main purpose of this work is to develop a coherent system identification based robust control design methodology by combining recent results from system identification and robust control. In order to accomplish this task new theoretical results will be given in both fields. Firstly, however......, an introduction to modern robust control design analysis and synthesis will be given. It will be shown how the classical frequency domain techniques can be extended to multivariable systems using the singular value decomposition. An introduction to norms and spaces frequently used in modern control theory......, a non-trivial problem which to some extent has been neglected by the theoreticians of robust control. An uncertainty specification has simply been assumed given. One way of obtaining a perturbation model is by physical modelling. Application if the fundamental laws of thermodynamics, mechanics, physics...
Seyal, Afzaal H.; Rahman, Mohd Noah A.
This study investigates the students' learning style, their attitudes about educational technologies in general and e-learning management system (e-LMS) in particular and their behavioral intentions to use the e-learning platform in a single institution of higher learning in Brunei Darussalam. In this study, a survey, using the VARK Questionnaire…
Alghamdi, Saleh Ramadhan; Bayaga, Anass
This paper was designed to establish the relationships between faculty members' use and attitude towards Learning Management Systems (LMSs). LMSs have been adopted in various educational institutions due to their numerous applications and functionalities to improve pedagogy. As a result, faculty members are urged to utilise them for enhancing…
Lenard, Mary Jane; Wessels, Susan; Khanlarian, Cindi
Using a model developed by Young (2000), this paper explores the relationship between performance in the Accounting Information Systems course, self-assessed computer skills, and attitudes toward computers. Results show that after taking the AIS course, students experience a change in perception about their use of computers. Females'…
Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....
Fateev, Alexey; Vassilyev, Alexander; Somov, Sergey
The solar-terrestrial reference frame is applied during a navigation satellite flight using onboard measured units of directions on the Sun and Earth, which are beginning in the satellite (Object) mass center. The angle between these units traditionally is named as the angle SOE (Sun - Object - Earth). We consider problems of attitude guidance and control at the spacecraft operation on specific parts of the orbit (singular orbit sites) at following values of the SOE angles — close to 0 deg (small SOE angles) and close to 180 deg (large SOE angles) with a view to minimizing the impact of solar pressure forces on the SC mass center motion.
Schlenker, S; Kersten, S; Hirschbuehl, D; Braun, H; Poblaguev, A; Oliveira Damazio, D; Talyshev, A; Zimmermann, S; Franz, S; Gutzwiller, O; Hartert, J; Mindur, B; Tsarouchas, CA; Caforio, D; Sbarra, C; Olszowska, J; Hajduk, Z; Banas, E; Wynne, B; Robichaud-Veronneau, A; Nemecek, S; Thompson, PD; Mandic, I; Deliyergiyev, M; Polini, A; Kovalenko, S; Khomutnikov, V; Filimonov, V; Bindi, M; Stanecka, E; Martin, T; Lantzsch, K; Hoffmann, D; Huber, J; Mountricha, E; Santos, HF; Ribeiro, G; Barillari, T; Habring, J; Arabidze, G; Boterenbrood, H; Hart, R; Marques Vinagre, F; Lafarguette, P; Tartarelli, GF; Nagai, K; D'Auria, S; Chekulaev, S; Phillips, P; Ertel, E; Brenner, R; Leontsinis, S; Mitrevski, J; Grassi, V; Karakostas, K; Iakovidis, G.; Marchese, F; Aielli, G
The ATLAS experiment is one of the multi-purpose experiments at the Large Hadron Collider (LHC), constructed to study elementary particle interactions in collisions of high-energy proton beams. Twelve different sub-detectors as well as the common experimental infrastructure are supervised by the Detector Control System (DCS). The DCS enables equipment supervision of all ATLAS sub-detectors by using a system of >130 server machines running the industrial SCADA product PVSS. This highly distributed system reads, processes and archives of the order of 106 operational parameters. Higher level control system layers allow for automatic control procedures, efﬁcient error recognition and handling, and manage the communication with external systems such as the LHC. This contribution ﬁrstly describes the status of the ATLAS DCS and the experience gained during the LHC commissioning and the ﬁrst physics data taking operation period. Secondly, the future evolution and maintenance constraints for the coming years an...
Donck, J.C.J. van der
Contamination influences a wide variety of industrial processes. For complex systems, contamination control, the collective effort to control contamination to such a level that it guarantees or even improves process or product functionality, offers a way for finding workable solutions. Central in
Barale, P.; Jacobson, V.; Kilgore, R.; Rondeau, D.
The on-line control system interface for magnet beam steering and focusing in the Bevalac is described. An Aydin model 5205B display generator was chosen. This display generator will allow the computer to completely rewrite a monitor screen in less than 50 ms and is also capable of controlling a color monitor. (PMA)
This updated edition of the industry standard reference on power system frequency control provides practical, systematic and flexible algorithms for regulating load frequency, offering new solutions to the technical challenges introduced by the escalating role of distributed generation and renewable energy sources in smart electric grids. The author emphasizes the physical constraints and practical engineering issues related to frequency in a deregulated environment, while fostering a conceptual understanding of frequency regulation and robust control techniques. The resulting control strategi
A. A. Lobaty
Full Text Available This paper extends the recently introduced approach for modeling and solving the optimal control problem of fixedswitched mode DC-DC power converter. DCDC converters are a class of electric power circuits that used extensively in regulated DC power supplies, DC motor drives of different types, in Photovoltaic Station energy conversion and other applications due to its advantageous features in terms of size, weight and reliable performance. The main problem in controlling this type converters is in their hybrid nature as the switched circuit topology entails different modes of operation, each of it with its own associated linear continuous-time dynamics.This paper analyses the modeling and controller synthesis of the fixed-frequency buck DC-DC converter, in which the transistor switch is operated by a pulse sequence with constant frequency. In this case the regulation of the DC component of the output voltage is via the duty cycle. The optimization of the control system is based on the formation of the control signal at the output.It is proposed to solve the problem of optimal control of a hybrid system based on the formation of the control signal at the output of the controller, which minimizes a given functional integral quality, which is regarded as a linear quadratic Letov-Kalman functional. Search method of optimal control depends on the type of mathematical model of control object. In this case, we consider a linear deterministic model of the control system, which is common for the majority of hybrid electrical systems. For this formulation of the optimal control problem of search is a problem of analytical design of optimal controller, which has the analytical solution.As an example of the hybrid system is considered a step-down switching DC-DC converter, which is widely used in various electrical systems: as an uninterruptible power supply, battery charger for electric vehicles, the inverter in solar photovoltaic power plants.. A
Zhang, Honghua; Wang, Zeguo
The attitude regulation for a liquid-filled spacecraft in the presence of low frequency sinusoidal disturbance is considered in this paper. The liquid-filled spacecraft is modelled as a rigid body attached with a simple pendulum. A novel control scheme is proposed, which is composed of Active Disturbance Rejection Control (ADRC), Positive Position Feedback (PPF), Extended State Observer (ESO) and Singular Spectrum Analysis (SSA). The unknown sloshing mode could be estimated from the combined ESO and SSA, and accordingly ADRC and PPF controller is designed for the stabilization of the spacecraft. Particularly, the parameters of the disturbance are not required as long as its frequency is lower than the sloshing one. The proposed approach could provide stabilization for the spacecraft, rejection for the disturbance, and active damping for the sloshing. Its effectiveness is validated by numerical simulations.
Full Text Available I analyze attitudes towards gun control from a recent survey of American high school students. For students who most closely identify as Republicans, cueing them to think about prior school shootings increases their agreement that armed staff in schools will improve safety and arming citizens will reduce risk of mass shootings. For those identifying as Democrats and Independents, providing them with selective information that certain states have loose gun control laws and low rates of gun violence makes them more supportive of gun rights. For Republicans, providing selective information that certain states have loose gun control laws and high rates of gun violence makes them less supportive of gun rights. These results suggest that emotional cues may exacerbate a priori biases, while informational cues may be more likely to change people’s minds about firearm policies.
Wang, Yan; Wang, Lei; Cui, Xianghua; Fang, Yuan; Chen, Qianqiu; Wang, Ya; Qiang, Yao
Self-regulatory resources and trait self-control have been found to moderate the impulse-behavior relationship. The current study investigated whether the interaction of self-regulatory resources and trait self-control moderates the association between implicit attitudes and food consumption. One hundred twenty female participants were randomly assigned to either a depletion condition in which their self-regulatory resources were reduced or a no-depletion condition. Participants' implicit attitudes for chocolate were measured with the Single Category Implicit Association Test and self-report measures of trait self-control were collected. The dependent variable was chocolate consumption in an ostensible taste and rate task. Implicit attitudes predicted chocolate consumption in depleted participants but not in non-depleted participants. However, this predictive power of implicit attitudes on eating in depleted condition disappeared in participants with high trait self-control. Thus, trait self-control and self-regulatory resources interact to moderate the prediction of implicit attitude on eating behavior. Results suggest that high trait self-control buffers the effect of self-regulatory depletion on impulsive eating. Copyright © 2015 Elsevier Ltd. All rights reserved.
Murray, Jane K; Mosteller, Jill R; Loberg, Jenny M; Andersson, Maria; Benka, Valerie A W
Fertility control is important for population management of owned and unowned cats, provides health benefits at the individual level and can reduce unwanted sexually dimorphic behaviors such as roaming, aggression, spraying and calling. This article reviews the available evidence regarding European and American veterinarian, owner and pedigree cat breeder attitudes toward both surgical sterilization and non-surgical fertility control. It additionally presents new data on veterinarians' and pedigree cat breeders' use of, and attitudes toward, alternative modalities of fertility control. Within the United States and Europe, the proportion of cats reported to be sterilized varies widely. Published estimates range from 27-93% for owned cats and 2-5% for cats trapped as part of a trap-neuter-return (TNR) program. In some regions and populations of cats, non-surgical fertility control is also used. Social context, cultural norms, individual preferences, economic considerations, legislation and professional organizations may all influence fertility control decisions for cats. Particularly in Europe, a limited number of non-surgical temporary contraceptives are available for cats; these include products with regulatory approval for cats as well as some used 'off label'. Non-surgical methods remove the risk of complications related to surgery and offer potential to treat more animals in less time and at lower cost; they may also appeal to pedigree cat breeders seeking temporary contraception. However, concerns over efficacy, delivery methods, target species safety, duration and side effects exist with current non-surgical options. Research is under way to develop new methods to control fertility in cats without surgery. US and European veterinarians place high value on three perceived benefits of surgical sterilization: permanence, behavioral benefits and health benefits. Non-surgical options will likely need to share these benefits to be widely accepted by the veterinary
O’Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael
Objective Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. Method The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. Results After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Conclusions Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites’ paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions. PMID:24204867
O'Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael
Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.
Full Text Available OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty. This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. RESULTS: After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58 was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46, which likely represents self-interest in retaining property (guns. CONCLUSIONS: Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.
Freire, Wilma B; Waters, William F; Rivas-Mariño, Gabriela
To analyze awareness, understanding, attitudes, and practices related to the nutritional traffic light system (NTLS) on processed food packaging in Ecuador. 21 discussions were held in focus groups (FG) in populations of various sizes in the coastal, mountainous, and eastern regions. Nine interviews were conducted with key informants (KI) representing large, medium, and small enterprises producing or selling processed foods. There were 171 FG participants, the majority of whom recognized and understood the NTLS. There was a certain amount of discussion around awareness of the NTLS and purchasing attitudes, and other factors such as taste, brand, or accessibility were considered. Attitudes were different between age groups: while the group of five- to nine-year-olds knew little about the NTLS and preferred homemade foods, the group of 15- to 19-year-olds was indifferent to the NTLS information and placed more value on other features, such as taste. Practices related to the purchase and consumption of processed foods highlighted seven different strategies that ranged from replacing the product to ignoring the NTLS information. The KIs did not agree with the policy, but they acknowledged having amended the content of some products to reduce fat, sugar, and salt. The NTLS has had a positive effect on awareness and understanding of the content of processed products. Practices related to purchasing and consuming processed foods would be improved by promotion of the nutritional labeling policy, trade control, and the monitoring and surveillance of its implementation.
Gal, Uri; Berente, Nicholas; Yoo, Youngjin
In 2004, National Aeronautics and Space Administration (NASA) implemented Full Cost, an activity-based accounting program through an agency-wide enterprise resource planning (ERP) implementation. We apply Foucault's notion of 'dressage' to highlight aspects of demonstrative control associated...... with this implementation effort and to outline the different dimensions along which control was distributed. We suggest that some elements of Full Cost and the ERP system were geared toward satisfying disciplinary requirements without necessarily contributing to productive activity. We term these elements dressage...... that the ideal of complete enterprise control remains unattainable, as aspects of demonstrative control are inevitably implicated within broader enterprise-wide control systems within contemporary organizations. We conclude with implications for research and practice....
Oleiro Seabra, Luis Filipe; The ATLAS collaboration
The ATLAS Forward Proton (AFP) detector is one of the forward detectors of the ATLAS experiment at CERN aiming at measuring momenta and angles of diffractively scattered protons. Silicon Tracking and Time-of-Flight detectors are located inside Roman Pot stations inserted into beam pipe aperture. The AFP detector is composed of two stations on each side of the ATLAS interaction point and is under commissioning. The detector is provided with high and low voltage distribution systems. Each station has vacuum and cooling systems, movement control and all the required electronics for signal processing. Monitoring of environmental parameters, like temperature and radiation, is also available. The Detector Control System (DCS) provides control and monitoring of the detector hardware and ensures the safe and reliable operation of the detector, assuring good data quality. Comparing with DCS systems of other detectors, the AFP DCS main challenge is to cope with the large variety of AFP equipment. This paper describes t...
Guo, Xiaoting; Sun, Changku; Wang, Peng; Huang, Lu
To determine the relative attitude between the objects on a moving base and the base reference system by a MEMS (Micro-Electro-Mechanical Systems) gyroscope, the motion information of the base is redundant, which must be removed from the gyroscope. Our strategy is to add an auxiliary gyroscope attached to the reference system. The master gyroscope is to sense the total motion, and the auxiliary gyroscope is to sense the motion of the moving base. By a generalized difference method, relative attitude in a non-inertial frame can be determined by dual gyroscopes. With the vision sensor suppressing accumulative drift of the MEMS gyroscope, the vision and dual MEMS gyroscope integration system is formed. Coordinate system definitions and spatial transform are executed in order to fuse inertial and visual data from different coordinate systems together. And a nonlinear filter algorithm, Cubature Kalman filter, is used to fuse slow visual data and fast inertial data together. A practical experimental setup is built up and used to validate feasibility and effectiveness of our proposed attitude determination system in the non-inertial frame on the moving base.
Ghasemi, S.; Khorasani, K.
In this paper, the problem of fault detection and isolation (FDI) of the attitude control subsystem (ACS) of spacecraft formation flying systems is considered. For developing the FDI schemes, an extended Kalman filter (EKF) is utilised which belongs to a class of nonlinear state estimation methods. Three architectures, namely centralised, decentralised, and semi-decentralised, are considered and the corresponding FDI strategies are designed and constructed. Appropriate residual generation techniques and threshold selection criteria are proposed for these architectures. The capabilities of the proposed architectures for accomplishing the FDI tasks are studied through extensive numerical simulations for a team of four satellites in formation flight. Using a confusion matrix evaluation criterion, it is shown that the centralised architecture can achieve the most reliable results relative to the semi-decentralised and decentralised architectures at the expense of availability of a centralised processing module that requires the entire team information set. On the other hand, the semi-decentralised performance is close to the centralised scheme without relying on the availability of the entire team information set. Furthermore, the results confirm that the FDI results in formations with angular velocity measurement sensors achieve higher level of accuracy, true faulty, and precision, along with lower level of false healthy misclassification as compared to the formations that utilise attitude measurement sensors.
Mcglinchey, L. F.
The thrust vector control (TVC) system of the Viking Orbiter 1975 is discussed. The purpose of the TVC system is to point the engine thrust at the vehicle center of mass and to maintain attitude stability during propulsive maneuvers. This is accomplished by mounting the engine in a two-axis gimbal system. The TVC system then controls the pointing of the engine by closed loop control of two linear actuators which extend or retract and rotate the engine in its gimbal system. The effect of the TVC on the velocity vector pointing error incurred during a propulsive maneuver is analyzed. Models for predicting the magnitude of the error for various propulsive maneuvers are developed.
Lung, Leung Kam
The performance of the Learning Fuzzy Logic Control System (LFLCS), developed in this thesis, has been evaluated. The Learning Fuzzy Logic Controller (LFLC) learns to control the motor by learning the set of teaching values that are generated by a classical PI controller. It is assumed that the classical PI controller is tuned to minimize the error of a position control system of the D.C. motor. The Learning Fuzzy Logic Controller developed in this thesis is a multi-input single-output network. Training of the Learning Fuzzy Logic Controller is implemented off-line. Upon completion of the training process (using Supervised Learning, and Unsupervised Learning), the LFLC replaces the classical PI controller. In this thesis, a closed loop position control system of a D.C. motor using the LFLC is implemented. The primary focus is on the learning capabilities of the Learning Fuzzy Logic Controller. The learning includes symbolic representation of the Input Linguistic Nodes set and Output Linguistic Notes set. In addition, we investigate the knowledge-based representation for the network. As part of the design process, we implement a digital computer simulation of the LFLCS. The computer simulation program is written in 'C' computer language, and it is implemented in DOS platform. The LFLCS, designed in this thesis, has been developed on a IBM compatible 486-DX2 66 computer. First, the performance of the Learning Fuzzy Logic Controller is evaluated by comparing the angular shaft position of the D.C. motor controlled by a conventional PI controller and that controlled by the LFLC. Second, the symbolic representation of the LFLC and the knowledge-based representation for the network are investigated by observing the parameters of the Fuzzy Logic membership functions and the links at each layer of the LFLC. While there are some limitations of application with this approach, the result of the simulation shows that the LFLC is able to control the angular shaft position of the
Krening, Samantha C.
A major science objective of the Cassini mission is to study Saturnian satellites. The gravitational properties of each Saturnian moon is of interest not only to scientists but also to attitude control engineers. When the Cassini spacecraft flies close to a moon, a gravity gradient torque is exerted on the spacecraft due to the mass of the moon. The gravity gradient torque will alter the spin rates of the reaction wheels (RWA). The change of each reaction wheel's spin rate might lead to overspeed issues or operating the wheel bearings in an undesirable boundary lubrication condition. Hence, it is imperative to understand how the gravity gradient torque caused by a moon will affect the reaction wheels in order to protect the health of the hardware. The attitude control telemetry from low-altitude flybys of Saturn's moons can be used to estimate the gravitational parameter of the moon or the distance between the centers of mass of Cassini and the moon. Flight data from several low altitude flybys of three Saturnian moons, Dione, Rhea, and Enceladus, were used to estimate the gravitational parameters of these moons. Results are compared with values given in the literature.
Fraser-Chanpong, Nathan (Inventor); Spain, Ivan (Inventor); Dawson, Andrew D. (Inventor); Bluethmann, William J. (Inventor); Lee, Chunhao J. (Inventor); Vitale, Robert L. (Inventor); Guo, Raymond (Inventor); Waligora, Thomas M. (Inventor); Akinyode, Akinjide Akinniyi (Inventor); Reed, Ryan M. (Inventor)
A vehicle includes a chassis, a modular component, and a central operating system. The modular component is supported by the chassis. The central operating system includes a component control system, a primary master controller, and a secondary master controller. The component control system is configured for controlling the modular component. The primary and secondary master controllers are in operative communication with the component control system. The primary and secondary master controllers are configured to simultaneously transmit commands to the component control system. The component control system is configured to accept commands from the secondary master controller only when a fault occurs in the primary master controller.
Fuad A. A.TRAYEK
Full Text Available Learning management system (LMS is a learning platform for both full time and distant learning students at the International Islamic University in Malaysia (IIUM. LMS becomes a tool for IIUM to disseminate information and learning resources to the students. The objectives of this study were to Ø investigate students' attitudes toward the use of LMS, Ø to verify the impact of perceived usefulness and perceived ease of use on attitude towards use of learning management system, Ø to examine the differences in attitudes toward the use of LMS between distance learning and full time students. There were 120 (70 full time and 50 distance learning students at the Institute of Education responded for the study. The collected data was analysed using descriptive statistics, t-test and Multiple Regression Analysis (MRA. The results of the study showed that perceived ease of use and perceived usefulness determine students' attitudes toward the use of LMS. However, this study did not find any significant differences between distance learning and full time students. According to the findings the study recommended that the University should continue using LMS because it is useful for both distance learning and full time students. Further suggestions are made to customize and upgrade the LMS suitable for innovative teaching and learning.
Full Text Available From evolutionary reasoning, we derived a novel hypothesis that ingroup derogation is an evolved response of behavioral immune system which follows the smoke detector principle and the functional flexibility principle. This hypothesis was tested and supported across three experiments. In Experiment 1, participants' group membership was manipulated by using a minimal group paradigm. The results indicated that mere social categorization alone - a heuristic cue that implies the differentiation between "us" and "them" - was sufficient to elicit ingroup derogation among Chinese participants, and, such an intergroup bias was positively associated with the perceived vulnerability to diseases, which was also more consistently associated with ingroup attitudes. Experiment 2 extended and partially replicated Experiment 1 by showing that when there were cues of diseases in the immediate physical environment, Chinese participants exaggerated their attitudes of ingroup derogation. The results also showed that this effect was mainly driven by outgroup attraction. Experiment 3 changed the method of disease manipulation, and found that Chinese participants responded more strongly to disease cues originating from ingroup members and that they endorsed more ingroup derogation attitudes even when the ingroup and outgroup members were both displaying cues of diseases. Taken together, these results reveal the previously unexplored effects of infectious diseases on ingroup derogation attitudes, and suggest an interesting linkage between the evolved behavioral immune system and the ingroup derogation.
Full Text Available OBJECTIVES: The objective of this study was to investigate the knowledge, attitudes and behavior of Turkish dentists in Samsun City regarding cross-infection control. MATERIAL AND METHODS: A questionnaire was designed to obtain information about procedures used for the prevention of cross-infection in dental practices and determine the attitudes and perceptions of respondent dental practitioners to their procedures. The study population included all dentists in the city of Samsun, Turkey, in April 2005 (n=184. The questionnaire collected data on sociodemographic characteristics, knowledge and practice of infection control procedures, sterilization, wearing of gloves, mask, use of rubber dam, method of storing instruments and disposal methods of contaminated material, etc. Questionnaire data was entered into a computer and analyzed by SPSS statistical software. RESULTS: From the 184 dentists to whom the questionnaires were submitted, 135 participated in the study (overall response rate of 73.36%. As much as 74.10% dentists expressed concern about the risk of cross-infection from patients to themselves and their dental assistants. Forty-three percent of the participants were able to define "cross-infection" correctly. The greatest majority of the respondents (95.60% stated that all patients have to be considered as infectious and universal precautions must apply to all of them. The overall responses to the questionnaire showed that the dentists had moderate knowledge of infection control procedures. CONCLUSIONS: Improved compliance with recommended infection control procedures is required for all dentists evaluated in the present survey. Continuing education programs and short-time courses about cross-infection and infection control procedures are suitable to improve the knowledge of dentists.
Tenna, Admasu; Stenehjem, Edward A; Margoles, Lindsay; Kacha, Ermias; Blumberg, Henry M; Kempker, Russell R
To better understand hospital infection control practices in Ethiopia. A cross-sectional evaluation of healthcare worker (HCW) knowledge, attitudes, and practices about hand hygiene and tuberculosis (TB) infection control measures. An anonymous 76-item questionnaire was administered to HCWs at 2 university hospitals in Addis Ababa, Ethiopia. Knowledge items were scored as correct/incorrect. Attitude and practice items were assessed using a Likert scale. In total, 261 surveys were completed by physicians (51%) and nurses (49%). Fifty-one percent of respondents were male; mean age was 30 years. While hand hygiene knowledge was fair, self-reported practice was suboptimal. Physicians reported performing hand hygiene 7% and 48% before and after patient contact, respectively. Barriers for performing hand hygiene included lack of hand hygiene agents (77%), sinks (30%), and proper training (50%) as well as irritation and dryness (67%) caused by hand sanitizer made in accordance with the World Health Organization formulation. TB infection control knowledge was excellent (more than 90% correct). Most HCWs felt that they were at high risk for occupational acquisition of TB (71%) and that proper TB infection control can prevent nosocomial transmission (92%). Only 12% of HCWs regularly wore a mask when caring for TB patients. Only 8% of HCWs reported that masks were regularly available, and 76% cited a lack of infrastructure to isolate suspected/known TB patients. Training HCWs about the importance and proper practice of hand hygiene along with improving hand sanitizer options may improve patient safety. Additionally, enhanced infrastructure is needed to improve TB infection control practices and allay HCW concerns about acquiring TB in the hospital.
CERN Neyrac Films
Part of the series of films produced by CERN about the SPS. Names, facts and credits added on the 1975 version by Bengt Sagnell, Meyrin, Oct 2012. The project leader for the SPS accelerator (with 400 staff) was John Adams - later Sir John. The group responsible for the design and installation of the control system was led by Michael Crowley-Milling. 00:02:14 Bernard Sutton00:02:48 Michael Crowley-Milling, Head of the Controls Group00:03:01 Designed in the Controls Group, this was probably the first use of touch screens in an industrial control system00:04:37 Louis Burnod, Section leader, Beam Instrumentation00:05:36 Claes Frisk, Computer technician 00:06:03 The system contained 24 Norsk Data NORD-10 16-bit mini computers with 16-64 kB of magnetic core memory and external hard disks of from 5MB to 256 MB in size00:06:23 Frank Beck, Section leader, Central Controls00:06:26 Véronique Frammery, Programmer 00:06:31 Hans-Karl Kuhn, Power Supply Controls00:07:55 Raymond Rausch, Control electronics00:10:23 Paul Acti...
Gibson, J W; Lanz, J B
Attitudes of 240 female Hispanic teenagers in 1984-85 in New York City toward the importance of birth control (ATIBC) are examined as a reflection of the following: demographic factors, educational aspirations, maternal characteristics, religiosity, clarity of longterm goals, and perception of friends' behavior, i.e., the degree, formation, and variation of these factors. The nonrandom sample was recruited from pregnancy prevention classes. The questionnaire was available in English or Spanish. 9 research questions were of interest including whether girls in female-headed households were more likely to be sexually active and have higher ATIBC scores, whether Catholics will have lower ATIBC scores, whether spanish preference speakers have lower ATIBC scores, whether working mothers' children, or more highly educated mothers' children were more sexually active and have higher scores, whether religiosity lowers scores, whether higher educational aspirations increases scores, whether childrens' beliefs that most of the friends use contraceptive is related to higher cores, and whether clearer longterm goals are related to higher scores. The attitude scale was based on Kirby's and Cvetkovich and Grote's work and focused on peer influence, parental attitudes, and strength of intention to use contraceptives. Other measures are identified by specific questions, i.e., clarity of longterm goals is measured by the question: I have a clear idea of where I'm headed in the future, and I know what I want out of life. The results indicated that 4 variables were significantly associated with ATIBC scores: 1) lower scores were associated with teenagers who had mothers with low education (2nd-9th grades), and 2) teenagers who spoke Spanish best; 3) perceived importance of religion was significantly related to lower ATIBC scores such that great importance was related to low scores and little importance was related to high scores; and 4) teenagers' belief about their friends' potential
Zhao, Xudong; Niu, Ben; Wu, Tingting
This book offers its readers a detailed overview of the synthesis of switched systems, with a focus on switching stabilization and intelligent control. The problems investigated are not only previously unsolved theoretically but also of practical importance in many applications: voltage conversion, naval piloting and navigation and robotics, for example. The book considers general switched-system models and provides more efficient design methods to bring together theory and application more closely than was possible using classical methods. It also discusses several different classes of switched systems. For general switched linear systems and switched nonlinear systems comprising unstable subsystems, it introduces novel ideas such as invariant subspace theory and the time-scheduled Lyapunov function method of designing switching signals to stabilize the underlying systems. For some typical switched nonlinear systems affected by various complex dynamics, the book proposes novel design approaches based on inte...
Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana
A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.
Kwatny, Harry G
This monograph explores a consistent modeling and analytic framework that provides the tools for an improved understanding of the behavior and the building of efficient models of power systems. It covers the essential concepts for the study of static and dynamic network stability, reviews the structure and design of basic voltage and load-frequency regulators, and offers an introduction to power system optimal control with reliability constraints. A set of Mathematica tutorial notebooks providing detailed solutions of the examples worked-out in the text, as well as a package that will enable readers to work out their own examples and problems, supplements the text. A key premise of the book is that the design of successful control systems requires a deep understanding of the processes to be controlled; as such, the technical discussion begins with a concise review of the physical foundations of electricity and magnetism. This is followed by an overview of nonlinear circuits that include resistors, inductors, ...
Adane, Kelemework; Spigt, Mark; Johanna, Laturnus; Noortje, Dorscheidt; Abera, Semaw Ferede; Dinant, Geert-Jan
Although awareness is an important component in tuberculosis (TB) control, we do not know how much Ethiopian prisoners know about TB. This study assessed the level of knowledge, attitudes, and practices (KAP) of prisoners about TB in eight northern Ethiopian prisons. Data were collected cross-sectionally from 615 prisoners using a standardized questionnaire between March and May 2016. The outcome variables were defined considering the basic elements about TB. Out of 615 prisoners, only 37.7% mentioned bacteria as a cause of TB while 21.7% related TB to exposure to cold wind. Eighty-eight per cent correctly mentioned the aerial route of TB transmission and 27.3% had perceived stigma towards TB. The majority (63.7%) was not aware of the possibility of getting multi-drug-resistant strains when they would not adhere to treatment. Overall, only 24% knew the basic elements about TB, 41% had favorable attitudes, and 55% had a good practice. Prisoners who were urban residents were generally more knowledgeable than rural residents (adjusted OR = 2.16; 95% CI = 1.15-4.06). Illiterates were found to be less knowledgeable (adjusted OR = 0.17; 95% CI = 0.06-0.46), less likely to have a favorable attitude (adjusted OR = 0.31; 95% CI = 0.15-0.64), and less good practice (adjusted OR = 0.35; 95% CI = 0.18-0.69). Significant differences were also observed between the different study prisons. Knowledge of prisoners regarding the cause of TB and consequences of non-adherence to TB treatment was low. Knowledge on the transmission, symptoms, and prevention was fairly high. Health education interventions, focused on the cause and the translation of the knowledge to appropriate practices, are needed in all the study prisons. Special attention should be given to less educated prisoners, and to prisons with a high number of prisoners and those in remote areas.
Full Text Available Abstract Background The Chinese National People's Congress ratified the WHO Framework Convention on Tobacco Control (FCTC on 27 August 2005, signaling China's commitment to implement tobacco control policies and legislation consistent with the treaty. This study was designed to examine attitudes towards four WHO FCTC measures among Chinese urban residents. Methods In a cross-sectional design study, survey data were collected from two Chinese urban cities involving a sample of 3,003 residents aged 15 years or older. Through a face-to-face interview, respondents were asked about attitudes toward four tobacco control measures developed by the WHO FCTC. Data on the four dependent measures were analyzed using multivariate logistic regression analyses. Using descriptive statistics, potential change in smoking behavior that smokers might make in response to increasing cigarette prices is also reported. Results 81.8% of the respondents in the study sample supported banning smoking in public places, 68.8% favored increasing the cigarette tax, 85.1% supported health warnings on cigarette packages, and 85.7% favored banning tobacco advertising. The likelihood to support these measures was associated with gender, educational level, and personal income. Smokers were less likely to support these measures than non-smokers, with decreased support expressed by daily smokers compared to occasional smokers, and heavy smokers compared to light smokers. The proportion of switching to cheaper cigarette brands, decreasing smoking, and quitting smoking altogether with increased cigarette prices were 29.1%, 30.90% and 40.0% for occasional smokers, respectively; and 30.8%, 32.7% and 36.5% for daily smokers, respectively. Conclusion Results from this study indicate strong public support in key WHO FCTC measures and that increases in cigarette price may reduce tobacco consumption among Chinese urban residents. Findings from this study have implications with respect to
Sørensen, Bjarne Taulo; Dutra de Barcellos, Marcia; Veflen Olsen, Nina
production, food and the environment, technological progress, animal welfare, local employment and local economy. In addition, the survey included a conjoint task by which participants’ evaluations of the importance of production system attributes were measured. The data were analysed by means of causal...
the training and visit (T&V) extension system as a complimentary step to specify if this extension approach is ... at 5 percent level of probability, the mean score for the project headquarters staff (106.25) was highest while ... which offered them the opportunity to use their knowledge and skills. Asiabiaka (1991) studied women ...
Scoffier, S; Paquet, Y; d'Arripe-Longueville, F
This study examined the influence of locus of control on disordered eating as mediated by the self-regulation of eating attitudes. The assessment instruments were adapted for athletes as the entire sample of 179 volunteer University students (M(age)=21.12; SD=2.87) were all regularly involved in competition. The results showed that (a) an internal locus of control had a positive influence on the self-regulation of eating attitudes in social interaction contexts; (b) self-regulatory eating attitudes had a negative influence on disordered eating in contexts of negative affect, social interaction, and lack of anticipation of consequences on performance; and (c) an internal locus of control had an influence on disordered eating through the mediation of self-regulatory eating attitudes in social interaction contexts, and an external locus of control attributed to the coach and sports friends had an influence on disordered eating through the mediation of self-regulatory eating attitudes in contexts of negative affect, social interaction and lack of anticipation of consequences on performance. This study, combined with an earlier study from Scoffier, Maïano, and d'Arripe-Longueville (2009) on the antecedents of athletes' eating disorders, suggests the powerful impact of the social environment on the development of disordered eating in athletes. 2010 Elsevier Ltd. All rights reserved.
Heaton Andrew; Stiltner, Brandon; Diedrich, Benjamin; Becker, Christopher; Orphee, Juan
The Attitude Control System (ACS) is developed for a Near Earth Asteroid (NEA) Scout mission using a solar sail. The NEA-Scout spacecraft is a 6U cubesat with an 86 square-meter solar sail. NEA Scout will launch on Space Launch System (SLS) Exploration Mission 1 (EM-1), currently scheduled to launch in 2018. The spacecraft will rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The solar sail spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Adjustable Mass Translator (AMT) system. The three subsystems allow for a wide range of spacecraft attitude control capabilities, needed for the different phases of the NEA-Scout mission. Because the sail is a flexible structure, care must be taken in designing a control system to avoid exciting the structural modes of the sail. This is especially true for the RCS, which uses pulse actuated, cold-gas jets to control the spacecraft's attitude. While the reaction wheels can be commanded smoothly, the RCS jets are simple on-off actuators. Long duration firing of the RCS jets - firings greater than one second - can be thought of as step inputs to the spacecraft's torque. On the other hand, short duration firings - pulses on the order of 0.1 seconds - can be thought of as impulses in the spacecraft's torque. These types of inputs will excite the structural modes of the spacecraft, causing the sail to oscillate. Sail oscillations are undesirable for many reasons. Mainly, these oscillations will feed into the spacecraft attitude sensors and pointing accuracy, and long term oscillations may be undesirable over the lifetime of the solar sail. In order to limit the sail oscillations, an RCS control scheme is being developed to minimize sail excitations. Specifically, an input shaping scheme similar to the method described in Reference 1 will be employed. A detailed description of the RCS control scheme will
Gómez-Reñasco, M. F.; Martín, Y.; Aguiar-González, M.; Cozar, J.; González-Cobos, N.; Hoyland, R.; Núñez Cagical, M.; Pérez-de-Taoro, M. R.; Sánchez-de la Rosa, V.; Vega-Moreno, A.; Viera-Curbelo, T.
The QUIJOTE-CMB experiment (Q-U-I JOint TEnerife CMB experiment) has been described in previous publications. In particular, the architecture of the MFI instrument control system, the first of the three QUIJOTE instruments, was presented in . In this paper we describe the control system architecture, hardware, and software, of the second QUIJOTE instrument, the TGI (Thirty GHz Instrument), which has been in the process of commissioning for a few weeks now. It is a 30 pixel 26-36 GHz polarimeter array mounted at the focus of the second QUIJOTE telescope. The polarimeter design is based on the QUIET polarimeter scheme, implementing phase switches of 90° and 180° to generate four states of polarisation. The TGI control system acquires the scientific signal of the four channels for each of the 30 polarimeters, sampled at 160 kHz; it controls the commutation of the 30 x 4 phase switches at 16 kHz or 8 kHz; it performs the acquisition and monitoring of the health of the complete instrument, acquiring housekeeping from the various subsystems and also controls the different operational modes of the telescope. It finally, implements a queue system that permits automation of the observations by allowing the programming of several days of observations with the minimum of human intervention. The acquisition system is based on a PXI-RT host from NI, the commutations of the phase switches are performed by a PXI-FPGA subsystem and the telescope control is based on an EtherCAT bus from Beckhoff.
de Barcellos, Marcia Dutra; Grunert, Klaus G.; Yanfeng, Z.
. A cross-sectional survey was carried out in six Chinese cities and 473 valid questionnaires were obtained. Results indicate that Chinese consumers prefer industrial pig production systems, where traditional pig breeds are raised, over large-scale and small family farms. Farms with maximum attention...... to food safety which furthermore can provide lean meat with consistent quality are also preferred compared to farms that have less focus on food safety. Chinese consumers also rejected imported pig breeds and tasty but variable meat....
Hernández, Oscar; Goulet, Céline; Lampron, Annie
With adolescence, boys and girls reach their sexual maturity and initiate their sexual encounters. They very frequently adopt risk behaviors as they tend not to use any contraceptive methods. Today's trend in relation to contraceptive methods is to recommend the combined utilization of condom and pill. In comparison to other methods, this last one, known as the Double Dutch (DD) method, has the advantage of preventing pregnancy and STD's, at the same time it increases the efficiency of contraception. Using the Theory of Planned Behavior the purpose of the study was to measure the intention, attitude, subjective norm and perceived behavioral control towards the utilization of the DD method among 15-16 year-old Spanish students and to determine the relationships among these variables. The results indicate that adolescents show favorable intention, attitude and subjective norm toward the utilization of the DD method. They seem to be more worried about pregnancy prevention than about STDs'prevention. Parents seem to be the most important reference people for adolescents, followed by their friends; the results show that at this age, adolescents tend to take into consideration these reference people's opinion.
Pereira, M. C.; de Melo, C. F.; Meireles, L. G.
Solar sails present a promising alternative method of propulsion for the coming phases of the space exploration. With the recent advances in materials engineering, the construction of lighter and more resistant materials capable of impelling spaceships with the use of solar radiation pressure has become increasingly viable technologically and economically. The studies, simulations and analysis of orbital transfers from Earth to Mars proposed in this work were implemented considering the use of a flat solar sail. Maneuvers considering the delivery of a sailcraft from a Low Earth Orbit to the border of the Earth’s sphere of influence and interplanetary trajectories to Mars were investigated. A set of simulations were implemented varying the attitude of the sail relative to the Sun. Results show that a sailcraft can carry out transfers with final velocity with respect to Mars smaller than the interplanetary Patched-conic approximation, although this requires a longer time of transfers, provided the attitude of the sailcraft relative to the Sun can be controlled in some points of the trajectories.
A closed-loop system consisting of a control system and an adaptive controller will be called tuning for a specified control objective if the real system and the ideal system defined below achieve the same value for the control objective. The real system is the system consisting of the unknown
Zhang, Jingrui; Yang, Keying; Qi, Rui
Tethered space-tug system is regarded as one of the most promising active debris removal technologies to effectively decrease the steep increasing population of space debris. In order to suppress the spin of space debris, single-tethered space-tug system is employed by regulating the tether. Unfortunately, this system is underactuated as tether length is the only input, and there are two control objectives: the spinning debris and the vibration of tether. Thus, it may suffer great oscillations and result in failure in space debris removal. This paper presents the study of attitude stabilization of the single-tethered space-tug system using not only tether length but also the offset of tether attachment point to suppress the spin of debris, so as to accomplish the space debris removal mission. Firstly, a precise 3D mathematical model in which the debris and tug are both treated as rigid bodies is developed to study the dynamical evolution of the tethered space-tug system. The relative motion equation of the system is described using Lagrange method. Secondly, the dynamic characteristic of the system is analyzed and an offset control law is designed to stabilize the spin of debris by exploiting the variation of tether offset and the regulation of tether length. Besides, an estimation formula is proposed to evaluate the capability of tether for suppressing spinning debris. Finally, the effectiveness of attitude stabilization by the utilization of the proposed scheme is demonstrated via numerical case studies.
This presentation will give a review from the operations team of the performance and issues of the beam based systems, namely RF, ADT, beam instrumentation, controls and injection systems. For each of these systems, statistics on performance and availability will be presented with the main issues encountered in 2012. The possible improvements for operational efﬁciency and safety will be discussed, with an attempt to answer the question "Are we ready for the new challenges brought by the 25ns beam and increased energy after LSI? ".
COMPUTER ASSISTED INVENTORY CONTROL SYSTEM. Alebachew Dessalegn and R. N. Roy. Department of Mechanical Engineering. Addis Ababa University. ABSTRACT. The basic purpose of holding inventories is to provide an essential decoupling between demand and unequal flow rate of materials in a supp~v ...
Smits, P B A; de Graaf, L; Radon, K; de Boer, A G; Bos, N R; van Dijk, F J H; Verbeek, J H A M
Undergraduate medical teaching in occupational health (OH) is a challenge in universities around the world. Case-based e-learning with an attractive clinical context could improve the attitude of medical students towards OH. The study question is whether case-based e-learning for medical students is more effective in improving knowledge, satisfaction and a positive attitude towards OH than non-case-based textbook learning. Participants, 141 second year medical students, were randomised to either case-based e-learning or text-based learning. Outcome measures were knowledge, satisfaction and attitude towards OH, measured at baseline, directly after the intervention, after 1 week and at 3-month follow-up. Of the 141 participants, 130 (92%) completed the questionnaires at short-term follow-up and 41 (29%) at 3-month follow-up. At short-term follow-up, intervention and control groups did not show a significant difference in knowledge nor satisfaction but attitude towards OH was significantly more negative in the intervention group (F=4.041, p=0.047). At 3-month follow-up, there were no significant differences between intervention and control groups for knowledge, satisfaction and attitude. We found a significant decrease in favourable attitude during the internship in the experimental group compared with the control group. There were no significant differences in knowledge or satisfaction between case-based e-learning and text-based learning. The attitude towards OH should be further investigated as an outcome of educational programmes.
E B Ryan
Full Text Available Understanding concerns about the welfare of farm animals is important for the development of socially sustainable production practices. This study used an online survey to test how views on group versus stall housing for pregnant sows varied when Canadian and US participants were provided information about these systems, including access to scientific papers, YouTube videos, Google images, and a frequently-asked-questions page (S1 Appendix. Initial responses and changes in responses after accessing the information were analyzed from Likert scores of 242 participants and from their written comments. Participants were less willing to accept the use of gestation stalls after viewing information on sow housing. For example, initially 30.4% of respondents indicated that they supported the use of gestation stalls; this declined to 17.8% after participants were provided additional information. Qualitative analysis of comments showed that supporters of gestation stalls expressed concern about the spread of disease and aggression between animals in less confined systems, whereas supporters of group housing placed more emphasis on the sow's ability to interact socially and perform natural behaviors. These results point to public opposition to the use of gestation stalls, and indicate that the more that the public learns about gestation stalls the less willing they will be to accept their use.
Full Text Available The orbital docking represents a problem of great importance in aerospace engineering. The paper aims to perform an analysis of docking maneuvers between a chaser vehicle and a target vehicle in permanent LEO (low earth orbit. The work begins with a study of the attitude dynamics modeling intended to define the strategy that facilitates the chaser movement toward a docking part of the target. An LQR (linear quadratic regulator approach presents an optimal control design that provides linearized closed-loop error dynamics for tracking a desired quaternion. The control law formulation is combined with the control architecture based on SDRE (State Dependent Riccati equation technique for rotational maneuvers, including the Earth oblateness perturbation. The chaser body-fixed frame must coincide with the target body-fixed frame at the docking moment. Then the implementation of the control architecture based on LQR technique using the computational tool MATLAB is carried out. In simulation of the docking strategy V-R bar operations are analyzed and the minimum accelerations needs the control of chaser vehicle. The simulation analysis of those maneuvers considered for a chaser vehicle and a target vehicle in LEO orbit is validated in a case study.
The present invention relates to an illumination control system comprising a plurality of outdoor luminaries and a motorized service vehicle. Each luminaire comprises a controllable light source producing a light illuminance. The motorized service vehicle comprises a light sensor configured...... to detect the light illuminance generated by the controllable light source at the motorized service vehicle. The motorized service vehicle computes light illuminance data based on the detected light illuminance and transmits these to the outdoor luminaire through a wireless communication link or stores...... the light illuminance data on a data recording device of the motorized service vehicle. The outdoor luminaire receives may use the light illuminance data to set or adjust a light illuminance of the controllable light source....
Silva, Kassondra M; Spinrad, Tracy L; Eisenberg, Nancy; Sulik, Michael J; Valiente, Carlos; Huerta, Snjezana; Edwards, Alison; Eggum, Natalie D; Kupfer, Anne S; Lonigan, Christopher J; Phillips, Beth M; Wilson, Shauna B; Clancy-Menchetti, Jeanine; Landry, Susan H; Swank, Paul R; Assel, Michael A; Taylor, Heather B
RESEARCH FINDINGS: The purpose of this study was to examine the relations of children's effortful control and quality of relationships with teachers to school attitudes longitudinally in an ethnically diverse and economically disadvantaged sample. Data were collected as part of a larger intervention project during mid-fall, winter, and late spring (ns = 823, 722, and 758, respectively) for 2 cohorts of 3- to 5-year-olds (collected during 2 different school years). Children's effortful control was assessed in the fall with parents' and teachers' reports and 2 behavioral measures. Teacher-child relationship quality was assessed mid-year with teachers' reports of closeness and conflict. Attitudes toward school were assessed in late spring using teachers' and students' reports of school avoidance and liking. Effortful control, in general, was positively correlated with teacher-child closeness and school liking and negatively correlated with conflict and school avoidance. Using structural equation modeling and controlling for sex and ethnicity, we found that effortful control was positively related to teacher-child relationship quality, which in turn was positively related to school attitudes. Furthermore, the relation of effortful control to school attitudes was mediated by teacher-child relationship quality. PRACTICE OR POLICY: Results provide evidence for the importance of relational processes that take place within the classroom context and have implications for teachers and clinicians working to increase school success in ethnic minority and low-income children.
Loreto, Michael; Kahn, Daniel; Glanc, Phyllis
The aim of this study was to investigate the attitudes and perceptions of staff radiologists regarding the incorporation of a nonanonymous peer review system at an academic hospital. A questionnaire gauging knowledge of, attitudes toward, and perceptions regarding peer review was distributed to all staff radiologists at a large academic hospital. The survey was distributed before the implementation of a nonanonymous peer review system. Data were analyzed using descriptive statistics. Responses were cross-tabulated according to subspecialty and number of years in practice. The majority of respondents agreed that peer review is important for improving patient care (31 of 36 [86%]) and professional development (29 of 36 [81%]), but the vast majority (33 of 36 [92%]) believed that peer review should be anonymous. Twenty-six of 36 respondents (72%) believed that peer review will not be safe from malpractice issues, 24 of 36 (67%) agreed that it has the potential to damage interpersonal relationships within the department, and 15 of 36 (42%) believed that it may influence their job security or rankings within the department. Significant differences were identified between radiologists with more and fewer years of practice experience. The incorporation of a nonanonymous peer review system generates anxiety and uncertainty within a radiology department. The investigation of physicians' attitudes toward and perceptions about peer review is important for understanding the potential impact not only on patient care but also on radiologists' relationships and psychology in the workplace. Copyright © 2014 American College of Radiology. Published by Elsevier Inc. All rights reserved.
Robert J. Turk
The Analysis Function of the US-CERT Control Systems Security Center (CSSC) at the Idaho National Laboratory (INL) has prepared this report to document cyber security incidents for use by the CSSC. The description and analysis of incidents reported herein support three CSSC tasks: establishing a business case; increasing security awareness and private and corporate participation related to enhanced cyber security of control systems; and providing informational material to support model development and prioritize activities for CSSC. The stated mission of CSSC is to reduce vulnerability of critical infrastructure to cyber attack on control systems. As stated in the Incident Management Tool Requirements (August 2005) ''Vulnerability reduction is promoted by risk analysis that tracks actual risk, emphasizes high risk, determines risk reduction as a function of countermeasures, tracks increase of risk due to external influence, and measures success of the vulnerability reduction program''. Process control and Supervisory Control and Data Acquisition (SCADA) systems, with their reliance on proprietary networks and hardware, have long been considered immune to the network attacks that have wreaked so much havoc on corporate information systems. New research indicates this confidence is misplaced--the move to open standards such as Ethernet, Transmission Control Protocol/Internet Protocol, and Web technologies is allowing hackers to take advantage of the control industry's unawareness. Much of the available information about cyber incidents represents a characterization as opposed to an analysis of events. The lack of good analyses reflects an overall weakness in reporting requirements as well as the fact that to date there have been very few serious cyber attacks on control systems. Most companies prefer not to share cyber attack incident data because of potential financial repercussions. Uniform reporting requirements will do much to make this
Stuck, B. W.
A research program into three aspects of space satellite dynamics was carried out. First, a four-dimensional space-time formulation of Newtonian mechanics is developed. This theory allows a new physical interpretation of the conservation theorems of mechanics first derived rigorously by Noether. Second, a new concept for estimating the three angles which specify the orientation in space of a rigid body is presented. Two separate methods for implementing this concept are discussed, one based on direction cosines, the other on quaternions. Two examples are discussed: constant orientation in space, and constant rate of change of the three angles with time. Third, two synchronous equatorial orbit communication satellite designs which use sunlight pressure to control their attitude are analyzed. Each design is equipped with large reflecting surfaces, called solar sails, which can be canted in different directions to generate torques to correct pointing errors.
J.H. van Schuppen (Jan)
textabstractA hybrid control system is a control theoretic model for a computer controlled engineering system. A definition of a hybrid control system is formulated that consists of a product of a finite state automaton and of a family of continuous control systems. An example of a transportation
The Encyclopedia of Systems and Control collects a broad range of short expository articles that describe the current state of the art in the central topics of control and systems engineering as well as in many of the related fields in which control is an enabling technology. The editors have assembled the most comprehensive reference possible, and this has been greatly facilitated by the publisher’s commitment continuously to publish updates to the articles as they become available in the future. Although control engineering is now a mature discipline, it remains an area in which there is a great deal of research activity, and as new developments in both theory and applications become available, they will be included in the online version of the encyclopedia. A carefully chosen team of leading authorities in the field has written the well over 200 articles that comprise the work. The topics range from basic principles of feedback in servomechanisms to advanced topics such as the control of Boolean networks...
Various examples of systems and methods are provided for Lyapunov control for uncertain systems. In one example, a system includes a process plant and a robust Lyapunov controller configured to control an input of the process plant. The robust Lyapunov controller includes an inner closed loop Lyapunov controller and an outer closed loop error stabilizer. In another example, a method includes monitoring a system output of a process plant; generating an estimated system control input based upon a defined output reference; generating a system control input using the estimated system control input and a compensation term; and adjusting the process plant based upon the system control input to force the system output to track the defined output reference. An inner closed loop Lyapunov controller can generate the estimated system control input and an outer closed loop error stabilizer can generate the system control input.
Full Text Available This paper is devoted to the research of multiagent voltage and reactive power control system development. The prototype of the system has been developed by R&D Center at FGC UES (Russia. The control system architecture is based on the innovative multiagent system theory application that leads to the achievement of several significant advantages (in comparison to traditional control systems implementation such as control system efficiency enhancement, control system survivability and cyber security.
Bissontz, Jay E.
A controller area network (CAN) installed on a hybrid electric vehicle provides one node with control of high voltage power distribution system isolation contactors and the capacity to energize a secondary electro-mechanical relay device. The output of the secondary relay provides a redundant and persistent backup signal to the output of the node. The secondary relay is relatively immune to CAN message traffic interruptions and, as a result, the high voltage isolation contactor(s) are less likely to transition open in the event that the intelligent output driver should fail.
Apathy, I.; Deme, S.; Feher, I.
An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station.
Awotidebe, Taofeek O; Adedoyin, Rufus A; Afolabi, Mubaraq A; Opiyo, Rose
Exercise plays significant role in the health outcomes of patients with diabetes, however, little is known about patients' knowledge of exercise for plasma blood glucose control among patients with type-2 diabetes (T2D). This study investigated knowledge, attitude and practice (KAP) of exercise for plasma blood glucose control among patients with T2D. This cross-sectional study recruited 299 patients with T2D (male=105; female=194) from selected government hospitals in Osun State, Nigeria using purposive sampling technique. Validated questionnaires were used to assess of exercise for plasma blood glucose control and socioeconomic status (SES) of the patients. Data were analysed using descriptive and inferential statistics. Alpha level was set at knowledge of exercise whilst 269(90.0%) had negative attitude to exercise practice. Less than a third, 82(27.4%) engaged in exercise practice for plasma blood glucose control. There was significant association between knowledge and practice of exercise ((2)=12.535; p=0.002). Furthermore, significant associations were found between knowledge and gender ((2)=11.453; p=0.003), and socioeconomic status ((2)=29.127, p=0.001) but not associated with attitude towards exercise (p>0.05). Patients with demonstrated good knowledge of exercise for plasma blood glucose control but reported negative attitude and poor practice of exercise. Copyright © 2016. Published by Elsevier Ltd.
Machine protection, as part of accelerator control systems, can be managed with a 'functional safety' approach, which takes into account product life cycle, processes, quality, industrial standards and cybersafety. This paper will discuss strategies to manage such complexity and the related risks, with particular attention to fail-safe design and safety integrity levels, software and hardware standards, testing, and verification philosophy. It will also discuss an implementation of a machine protection system at the SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS).
This book is intended for IT professionals working with Hyper-V, Azure cloud, VMM, and private cloud technologies who are looking for a quick way to get up and running with System Center 2012 R2 App Controller. To get the most out of this book, you should be familiar with Microsoft Hyper-V technology. Knowledge of Virtual Machine Manager is helpful but not mandatory.
This text is concerned with identifying and outlining the various aspects of logistics control and performance measurement process. The objective is to identify, based on available literature, methods and techniques which can be used to measure the performance of logistics. Logistics management is essentially a task of balancing between minimizing cost and ensuring availability objectives. Availability can be seen as the output of logistics system. On the input side, management is concer...
Morgenstern, Wendy M.; Bourkland, Kristin L.; Hsu, Oscar C.; Liu, Kuo-Chia; Mason, Paul A. C.; O'Donnell, James R., Jr.; Russo, Angela M.; Starin, Scott R.; Vess, Melissa F.
The Solar Dynamics Observatory (SDO) was designed and built at the Goddard Space Flight Center, launched from Cape Canaveral on February 11, 2010, and reached its final geosynchronous science orbit on March 16, 2010. The purpose of SDO is to observe the Sun and continuously relay data to a dedicated ground station. SDO remains Sun-pointing throughout most of its mission for the instruments to take measurements of the Sun. The SDO attitude control system (ACS) is a single-fault tolerant design. Its fully redundant attitude sensor complement includes sixteen coarse Sun sensors (CSSs), a digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), and two star trackers (STs). The ACS also makes use of the four guide telescopes included as a part of one of the science instruments. Attitude actuation is performed using four reaction wheels assemblies (RWAs) and eight thrusters, with a single main engine used to provide velocity-change thrust for orbit raising. The attitude control software has five nominal control modes, three wheel-based modes and two thruster-based modes. A wheel-based Safehold running in the attitude control electronics box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. This paper details the final overall design of the SDO guidance, navigation, and control (GN&C) system and how it was used in practice during SDO launch, commissioning, and nominal operations. This overview will include the ACS control modes, attitude determination and sensor calibration, the high gain antenna (HGA) calibration, and jitter mitigation operation. The Solar Dynamics Observatory mission is part of the NASA Living With a Star program, which seeks to understand the changing Sun and its effects on the Solar System, life, and society. To this end, the SDO spacecraft carries three Sun
Rolf Andreas Rasenack
Full Text Available Control systems are sets of interconnected hardware and software components which regulate the behaviour of processes. The software of modern control systems rises for some years by requirements regarding the flexibility and functionality. Thus the force of innovation grows on enterprises, since ever newer products in ever shorter time intervals must be made available. Associated hereby is the crucial shortening of the product life cycle, whose effects show up in reduced care of the software and the spares inventory. The aim, the concept presented here and developed in a modeling environment, is proved and ensures a minimum functionality of software components. Replacing software components of a control system verified for functionality by a framework at run-time and if necessary the software conditions will become adapted. Quintessential point of this implementation is the usage of an abstract syntax tree. Within its hierarchical structure meta information is attached to nodes and processed by the framework. With the development of the concept for semantic proving of software components the lifetime of software-based products is increased.
With the advent of the Tevatron, considerable upgrades have been made to the controls of all the Fermilab Accelerators. The current system is based on making as large an amount of data as possible available to many operators or end-users. Specifically there are about 100 000 separate readings, settings, and status and control registers in the various machines, all of which can be accessed by seventeen consoles, some in the Main Control Room and others distributed throughout the complex. A "Host" computer network of approximately eighteen PDP-11/34's, seven PDP-11/44's, and three VAX-11/785's supports a distributed data acquisition system including Lockheed MAC-16's left from the original Main Ring and Booster instrumentation and upwards of 1000 Z80, Z8002, and M68000 microprocessors in dozens of configurations. Interaction of the various parts of the system is via a central data base stored on the disk of one of the VAXes. The primary computer-hardware communication is via CAMAC for the new Tevatron and Antiproton Source; certain subsystems, among them vacuum, refrigeration, and quench protection, reside in the distributed microprocessors and communicate via GAS, an in-house protocol. An important hardware feature is an accurate clock system making a large number of encoded "events" in the accelerator supercycle available for both hardware modules and computers. System software features include the ability to save the current state of the machine or any subsystem and later restore it or compare it with the state at another time, a general logging facility to keep track of specific variables over long periods of time, detection of "exception conditions" and the posting of alarms, and a central filesharing capability in which files on VAX disks are available for access by any of the "Host" processors.
Lynne M. Stevens
A preeminent objective for corporate and government organizations is the protection of major investments, which is attained by achieving state awareness, a comprehensive understanding of security and safety, for critical infrastructures. Given the dependence of critical infrastructure on control systems for automation, the integrity of these systems and their ability to provide owner/operators a high degree of state awareness is essential in attaining a high degree of investment protection and public acceptance. Operators as well as government are therefore burdened to ensure they have a timely understanding of the status of their plant or all plants, respectively, to ensure efficient operations and investment and public protection. “This characterization is a significant objective that must consider many aspects of instrumentation, control, and intelligent systems in order to achieve the required result. These aspects include sensory, communication, analysis, decision, and human system interfaces necessary to achieve fusion of data and presentation of results that will provide an understanding of what issues are important and why.
Bursey, M; Craig, D
The purpose of this study was to examine the relationships between intention, attitudes, subjective norm, and perceived behavioral control related to smoking cessation in adults after initial coronary artery bypass graft surgery (CABG). The theoretical framework for the study was derived from Ajzen's Theory of Planned Behavior. Intention, the global and belief-based measures of attitude, subjective norm, and perceived behavioral control were measured with the Determinants of Adult Smoking Cessation (DOASC) Questionnaire developed by the investigator. Thirty-two adult smokers completed the questionnaire 2 to 3 weeks following hospital discharge. Four weeks after the questionnaire completion, a follow-up telephone call was used to determine the participants' current smoking status. The study results indicated that there was a statistically significant relationship between the intention to quit smoking after CABG and the global measure of attitude, and perceived behavioral control. This study highlights some of the beliefs about the outcomes of quitting smoking permanently after CABG which may underlie attitudes, subjective norm, and perceived behavioral control in this population. Implications for theory, practice, and research are discussed.
White, Katherine M.; Wellington, Larne
We examined the theory of planned behavior (TPB) in predicting intentions to participate in group parenting education. One hundred and seventy-six parents (138 mothers and 38 fathers) with a child under 12 years completed TPB items assessing attitude, subjective norms, perceived behavioral control (PBC), and two additional social influence…
Islam, Tariqul; Islam, Md. Saiful; Shajid-Ul-Mahmud, Md.; Hossam-E-Haider, Md
An Attitude Heading Reference System (AHRS) provides 3D orientation of an aircraft (roll, pitch, and yaw) with instantaneous position and also heading information. For implementation of a low cost AHRS system Micro-electrical-Mechanical system (MEMS) based sensors are used such as accelerometer, gyroscope, and magnetometer. Accelerometers suffer from errors caused by external accelerations that sums to gravity and make accelerometers based rotation inaccurate. Gyroscopes can remove such errors but create drifting problems. So for getting the precise data additionally two very common and well known filters Complementary and Kalman are introduced to the system. In this paper a comparison of system performance using these two filters is shown separately so that one would be able to select filter with better performance for his/her system.
... 49 Transportation 3 2010-10-01 2010-10-01 false Control systems. 193.2619 Section 193.2619...: FEDERAL SAFETY STANDARDS Maintenance § 193.2619 Control systems. (a) Each control system must be properly adjusted to operate within design limits. (b) If a control system is out of service for 30 days or more, it...
Bendtsen, Jan Dimon; Trangbæk, K; Stoustrup, Jakob
Often, when new sensor or actuator hardware be- comes available for use in a control system, it is desirable to retain the existing control system and apply the new control capabilities in a gradual fashion rather than decommissioning the entire existing system and replacing it with an altogether...... new control system. However, this requires that the existing controller remains in action, and the new control law component is added to the existing system. This paper formally introduces the concept of Plug-and-Play control and proposes two different methods of introducing new control components...... in a smooth manner, providing stability guarantees during the transition phase as well as retaining the original control structure. The applicability of the methods is illustrated on two different practical example systems, a livestock stable climate control system and a laboratory-scale model of a district...
Abundant and affordable energy is required for U.S. economic stability and national security. Advanced nuclear power plants offer the best near-term potential to generate abundant, affordable, and sustainable electricity and hydrogen without appreciable generation of greenhouse gases. To that end, Idaho National Laboratory (INL) has been charged with leading the revitalization of nuclear power in the U.S. The INL vision is to become the preeminent nuclear energy laboratory with synergistic, world-class, multi-program capabilities and partnerships by 2015. The vision focuses on four essential destinations: (1) Be the preeminent internationally-recognized nuclear energy research, development, and demonstration laboratory; (2) Be a major center for national security technology development and demonstration; (3) Be a multi-program national laboratory with world-class capabilities; (4) Foster academic, industry, government, and international collaborations to produce the needed investment, programs, and expertise. Crucial to that effort is the inclusion of research in advanced instrumentation, control, and intelligent systems (ICIS) for use in current and advanced power and energy security systems to enable increased performance, reliability, security, and safety. For nuclear energy plants, ICIS will extend the lifetime of power plant systems, increase performance and power output, and ensure reliable operation within the system's safety margin; for national security applications, ICIS will enable increased protection of our nation's critical infrastructure. In general, ICIS will cost-effectively increase performance for all energy security systems.
Burke, F M; O'Mullane, D; O'Sullivan, M
Dental unit water systems (DUWS) are used in dental practices to provide water to irrigate the oral cavity. Dental surgeries across the European Union (EU) use DUWS that may be prone to microbial contamination. To determine Irish dental practitioners' attitudes to perceived risk from working with DUWS and their protocols for the management of biofilm in their DUWS and compare these with other European dentists. A questionnaire was used to determine DUWS types in use, practitioners' attitudes to risks associated with using DUWS and their DUWS management protocols. There were six different types of DUWS, 40 per cent of which were > 5 years old, 42 per cent of DUWS were fed by purified or distilled water. Only four per cent of practitioners carried out microbiological analysis on their water, but 38 per cent indicated that they cleaned or disinfected their DUWS. One-hundred per cent of practitioners were not aware of national/international guidelines for microbial contamination of DUWS but 77 per cent were concerned about DUWS water quality. The majority of practitioners were working with equipment that is dental unit water quality and would welcome regular microbiological water tests and clear advice on cleaning/disinfection of the water supply in their dental units. Practitioner attitudes and behaviours were broadly similar in the other European countries studied.
Gillani Syed Wasif
Full Text Available A six-month longitudinal intervention arm study with a pre-post cross-sectional questionnaire-based survey was performed. A 3-phase objective structured clinical examination (OSCE design was utilized for evaluation of acceptance and attitude of pharmacy students towards clinical pharmacy services. The pre-OSCE survey showed increased disagreement with the role of clinical pharmacists, compared to a significant positive shift in attitude towards their services in the healthcare team after 6 months of the trial. Responses improved for awareness (the current healthcare system could be improved by involving pharmacists, p < 0.02 and positive attitude categories (doctors and nurses would be happy to welcome the services of competent clinical pharmacists as part of their team, p < 0.01 in addition to competency (pharmacists have sufficient clinical training to advise doctors and nurses, p < 0.01. The predictive model suggested a strong positive effect on patient interaction, medical information tasks, clinical decisions on drug-related problems (DRPs, and communication with healthcare professionals (R2 = 0.41, F = 1.51, p < 0.001.
Lydia Bares López
Full Text Available The European Higher Education Area (EHEA involves changing traditional methods to promote innovative teaching experiences. This paper has two main aims: a to show evidence of the use of Interactive Response Systems (IRS to identify gaps in the understanding of the course contents and b to investigate factors influencing students’ attitudes towards the use of IRS. The experience was developed through a collective tutoring session in the subject of Economics using IRS. Economics is a first-year subject in the Degree of Business Administration and Management offered by the University of Cadiz, which includes contents of Microeconomics and Macroeconomics and uses economic models to explain the function of the economy and the behaviour of economic agents. Results show that IRS technique allows detecting gaps in learning and comprehension. From our econometric estimations, we also identify two strongly significant variables affecting students’ attitudes towards IRS: gender and received explanations regarding the use of IRS. Variables such as first enrolment in the subject and the number of hours devoted to studying have a positive and significant effect on the attitude to IRS, but at a lower level of significance (from 5% to 10%.
mohamad hasan Eftekhari
Full Text Available Background : Adolescence is one of the most critical growth periods in the human's life. Eating disorder is one of the most common nutritional-psychological disorders in this period, which can lead to acute and chronic physical and mental problems. Therefore, regarding the importance of the topic, the present study was designed to determine the prevalence of weight – controlling attitude and eating disorders, and their association with anthropometric indices in female adolescent school students. Materials and Methods: The present study was a cross-sectional descriptive analytical study. 594 high school adolescent girls were selected using multi-stage random sampling method. Nutritional attitude was assessed by use of a nutritional attitude questionnaire. Another specific questionnaire was used to gather demographic and anthropometric information. Data analysis was done using SPSS software, independent t- test and Chi-square (P˂0.05. Results: The information shows that 80% of the studied population are at risk of eating disorders. The number of the obese , over weight and underweight students were significantly more in the group with nutritional attitude disorders. Conclusion: Due to the high prevalence of eating disorders in adolescent girls, and the concomitant obesity and underweight with these disorders, the correction of these attitude could be mentioned as a health priority in this city
Kecklund, Göran; Eriksen, Claire Anne; Akerstedt, Torbjörn
It is often claimed that shift workers give priority to long series of days off and therefore prefer compressed work schedules at the expense of what is optimal for long-term health. The aim of the present study was to evaluate the attitude to six new shift systems among a randomly selected sample of police officers. The results showed that the most popular shift system was a rapidly, forward, rotating schedule with at least 16 h of rest between shifts, despite that it had fewer days off compared with some of the compressed shift systems. However, the individual differences were large and many individuals (32%) disliked the rapidly rotating shift system. Young age was associated with a positive attitude to the rapidly rotating shift system. The attitude to the shift system was also influenced by the present schedule, and shift systems that were similar to the present work hours received more positive evaluation. Sleep and health complaints showed no association with the attitude to the shift systems. In conclusion, the shift workers attitude to the new schedules was partly in agreement with the ergonomic recommendations of the design of three-shift systems that will facilitate sufficient sleep and minimize negative health consequences.
O'Donnell, James R., Jr.; Hsu, Oscar; Maghami, Peiman
The Space Technology-7 (ST-7) Disturbance Reduction System (DRS) is an experiment package aboard the European Space Agency (ESA) LISA Pathfinder spacecraft, launched on December 3, 2015. DRS consists of three primary components: Colloidal MicroNewton Thrusters (CMNTs), an Integrated Avionics Unit (IAU), and flight-software implementing the Command and Data Handling (C&DH) and Dynamic Control System (DCS) algorithms. The CMNTs were designed to provide thrust from 5 to 30 micro Newton, with thrust controllability and resolution of 0.1 micro Newton and thrust noise of 0.1 micro Newton/(square root of (Hz)) in the measurement band from 1-30 mHz. The IAU hosts the C&DH and DCS flight software, as well as interfaces with both the CMNT electronics and the LISA Pathfinder spacecraft. When in control, the DCS uses star tracker attitude data and capacitive or optically-measured position and attitude information from LISA Pathfinder and the LISA Technology Package (LTP) to control the attitude and position of the spacecraft and the two test masses inside the LTP. After completion of the nominal ESA LISA Pathfinder mission, the DRS experiment was commissioned followed by its nominal mission. DRS operations extended over the next five months, interspersed with station keeping, anomaly resolution, and periods where control was handed back to LISA Pathfinder for them to conduct further experiments. The primary DRS mission ended on December 6, 2016, with the experiment meeting all of its Level 1 requirements. The DCS, developed at the NASA Goddard Space Flight Center, consists of five spacecraft control modes and six test mass control modes, combined into six 'DRS Mission Modes'. Attitude Control and Zero-G were primarily used to control the spacecraft during initial handover and during many of the CMNT characterization experiments. The other Mission Modes, Drag Free Low Force, 18-DOF Transitional, and 18-DOF, were used to provide drag-free control of the spacecraft about the test
Kannan, Suresh K.
This thesis extends the use of neural-network-based model reference adaptive control to systems that occur as cascades. In general, these systems are not feedback linearizable. The approach taken is that of approximate feedback linearization of upper subsystems whilst treating the lower-subsystem states as virtual actuators. Similarly, lower-subsystems are also feedback linearized. Typically, approximate inverses are used for linearization purposes. Model error arising from the use of an approximate inverse is minimized using a neural-network as an adaptive element. Incorrect adaptation due to (virtual) actuator saturation and dynamics is avoided using the Pseudocontrol Hedging method. Using linear approximate inverses and linear reference models generally result in large desired pseudocontrol for large external commands. Even if the provided external command is feasible (null-controllable), there is no guarantee that the reference model trajectory is feasible. In order to mitigate this, nonlinear reference models based on nested-saturation methods are used to constrain the evolution of the reference model and thus the plant states. The method presented in this thesis lends itself to the inner-outer loop control of air vehicles, where the inner-loop controls attitude dynamics and the outer-loop controls the translational dynamics of the vehicle. The outer-loop treats the closed loop attitude dynamics as an actuator. Adaptation to uncertainty in the attitude, as well as the translational dynamics, is introduced, thus minimizing the effects of model error in all six degrees of freedom and leading to more accurate position tracking. A pole-placement approach is used to choose compensator gains for the tracking error dynamics. This alleviates timescale separation requirements, allowing the outer loop bandwidth to be closer to that of the inner loop, thus increasing position tracking performance. A poor model of the attitude dynamics and a basic kinematics model is
Full Text Available Feasible real-time swing angle measurement is significant to improve the efficiency and safety of industrial crane systems. This paper presents a wireless microelectromechanical system (MEMS-based swing angle measurement system. The system consists of two attitude heading reference system (AHRS sensing units with a wireless communication function, which are mounted on the hook (or payload and the jib (or base of the crane, respectively. With a combination of a three-axis accelerometer, a three-axis gyroscope and a three-axis magnetometer, the standard extended Kalman filter (EKF is used to estimate the desired orientation of the payload and the base. Wireless ZigBee communication is employed to transmit the orientation of the payload to the sensing unit mounted on the base, which measures the orientation of the base. Because several physical parameters from the payload to the base can be acquired from the original crane control system, the swing angles of the payload can be calculated based on the two measured orientation parameters together with the known physical parameters. Experiments were performed to show the feasibility and effectiveness of the proposed swing angle measurement system.
The book reports on the latest advances and applications of nonlinear control systems. It consists of 30 contributed chapters by subject experts who are specialized in the various topics addressed in this book. The special chapters have been brought out in the broad areas of nonlinear control systems such as robotics, nonlinear circuits, power systems, memristors, underwater vehicles, chemical processes, observer design, output regulation, backstepping control, sliding mode control, time-delayed control, variables structure control, robust adaptive control, fuzzy logic control, chaos, hyperchaos, jerk systems, hyperjerk systems, chaos control, chaos synchronization, etc. Special importance was given to chapters offering practical solutions, modeling and novel control methods for the recent research problems in nonlinear control systems. This book will serve as a reference book for graduate students and researchers with a basic knowledge of electrical and control systems engineering. The resulting design proce...
Martin E. Cobern
The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.
Martin E. Cobern
The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed. The month of June, 2004 was primarily occupied with the writing of the Phase I Final Report, the sole deliverable of Phase I, which will be submitted in the next quarter. Redesign of the laboratory prototype and design of the downhole (Phase II) prototype was
Ferg, D. A.
The thermionic reactor control system design studies conducted over the past several years for a nuclear electric propulsion system are described and summarized. The relevant reactor control system studies are discussed in qualitative terms, pointing out the significant advantages and disadvantages including the impact that the various control systems would have on the nuclear electric propulsion system design. A recommendation for the reference control system is made, and a program for future work leading to an engineering model is described.
Wang, Yan; Ding, Ye; Song, Daoping; Zhu, Daqiao; Wang, Jianrong
Obese individuals frequently experience weight-related bias or discrimination-even in healthcare settings. Although obesity bias has been associated with several demographic factors, little is known about the association of weight locus of control with bias against overweight persons or about weight bias among Chinese health professionals. The aim of the study was to examine attitudes toward obese patients in a sample of Chinese registered nurses (RNs) and the relationship between weight bias and nurses' weight locus of control. RNs working in nine community health service centers across Shanghai, China, answered three self-report questionnaires: The Attitudes Toward Obese Persons Scale (ATOP), the External Weight Locus of Control Subscale (eWLOC) from the Dieting Belief Scale, and a sociodemographic profile. Hierarchical, stepwise, multiple regression was used to predict ATOP scores. From among 385 invited, a total of 297 RNs took part in the study (77.1% response rate). Participants scored an average of 71.04 on the ATOP, indicating slightly positive attitudes toward obese persons, and 30.08 on the eWLOC, indicating a belief in the uncontrollability of body weight. Using hierarchical, stepwise, multiple regression, two predictors of ATOP scores were statistically significant (eWLOC scores and status as a specialist rather than generalist nurse), but explained variance was low. Chinese RNs seemed to have relatively neutral or even slightly positive attitudes toward obese persons. Those nurses who believed that obesity was beyond the individual's control or worked in specialties were more likely to have positive attitudes toward obese people. Improved understanding of the comprehensive etiology of obesity is needed.
Full Text Available Early childhood care and education providers (CCPs work with over 7 million young children. These children are vulnerable to physical, sexual and emotional abuse, and neglect. However, CCPs make less than 1% of all reports of suspected child abuse and neglect that are made to child protective services. CCPs are therefore an untapped resource in the public health response to child maltreatment. However, their knowledge and attitudes about duties to report child maltreatment are poorly understood. Moreover, no rigorous research has tested whether their knowledge and attitudes about reporting child maltreatment can be improved. These gaps in knowledge are important because knowledge of the duty and positive attitudes towards it produce more effective reporting, and little evidence exists about how to enhance cognitive and affective attributes. Using the CONSORT approach, we report a single-blind test-retest randomized controlled trial evaluating iLook Out for Child Abuse, a customized online educational intervention for CCPs to increase knowledge and attitudes towards the reporting duty. 762 participants were randomized with results analyzed for 741 participants (372 in the intervention group; 369 in the control. Knowledge of the reporting duty increased in the intervention group from 13.54 to 16.19 out of 21 (2.65 increase, 95% CI: (2.37, 2.93; large effect size 0.95, p < 0.001; the control group remained stable, moving from 13.54 to 13.59 (0.05 increase, 95% CI: (-0.12, 0.22; negligible effect size 0.03, p = 0.684. Attitudes were enhanced on all 13 items for the intervention group, remaining stable in the control, with significant differences between groups on all items (p < 0.05. Gains were largely sustained at four month follow-up. Findings support education for CCPs and other professions. Future research should also explore effects of education on reporting behavior.US National Institutes of Health NCT02225301.
Thompson Joseph William
Full Text Available Wave-Based Control has been previously applied successfully to simple under-actuated flexible mechanical systems. Spacecraft and rockets with structural flexibility and sloshing are examples of such systems but have added difficulties due to non-uniform structure, external disturbing forces and non-ideal actuators and sensors. The aim of this paper is to extend the application of WBC to spacecraft systems, to compare the performance of WBC to other popular controllers and to carry out experimental validation of the designed control laws. A mathematical model is developed for an upper stage accelerating rocket moving in a single plane. Fuel sloshing is represented by an equivalent mechanical pendulum model. A wave-based controller is designed for the upper stage AVUM of the European launcher Vega. In numerical simulations the controller successfully suppresses the sloshing motion. A major advantage of the strategy is that no measurement of the pendulum states (sloshing motion is required.
Golubovic, Edin; Baran, Eray Abdurrahman; Şabanoviç, Asif; Sabanovic, Asif
This paper discusses the trajectory generation algorithm, contour error construction method and finally the contour controller design. In the trajectory generation algorithm combination of elliptical Fourier descriptors (EFD) and time based spline approximation (TBSA) is used to generate position, velocity and acceleration references.Contour error is constructed using transformation of trajectory tracking errors. Transformation is computationally efficient and requires only reference velocity...
Zhai, Ruiyong; Zhou, Zhaoying; Zhang, Wendong; Sang, Shengbo; Li, Pengwei
This paper presents a flight control and navigation system for a fixed-wing unmanned aerial vehicle (UAV) with low-cost micro-electro-mechanical system (MEMS) sensors. The system is designed under the inner loop and outer loop strategy. The trajectory tracking navigation loop is the outer loop of the attitude loop, while the attitude control loop is the outer loop of the stabilization loop. The proportional-integral-derivative (PID) control was adopted for stabilization and attitude control. The three-dimensional (3D) trajectory tracking control of a UAV could be approximately divided into lateral control and longitudinal control. The longitudinal control employs traditional linear PID feedback to achieve the desired altitude of the UAV, while the lateral control uses a non-linear control method to complete the desired trajectory. The non-linear controller can automatically adapt to ground velocity change, which is usually caused by gust disturbance, thus the UAV has good wind resistance characteristics. Flight tests and survey missions were carried out with our self-developed delta fixed-wing UAV and MEMS-based autopilot to confirm the effectiveness and practicality of the proposed navigation method.
Full Text Available This paper presents a flight control and navigation system for a fixed-wing unmanned aerial vehicle (UAV with low-cost micro-electro-mechanical system (MEMS sensors. The system is designed under the inner loop and outer loop strategy. The trajectory tracking navigation loop is the outer loop of the attitude loop, while the attitude control loop is the outer loop of the stabilization loop. The proportional-integral-derivative (PID control was adopted for stabilization and attitude control. The three-dimensional (3D trajectory tracking control of a UAV could be approximately divided into lateral control and longitudinal control. The longitudinal control employs traditional linear PID feedback to achieve the desired altitude of the UAV, while the lateral control uses a non-linear control method to complete the desired trajectory. The non-linear controller can automatically adapt to ground velocity change, which is usually caused by gust disturbance, thus the UAV has good wind resistance characteristics. Flight tests and survey missions were carried out with our self-developed delta fixed-wing UAV and MEMS-based autopilot to confirm the effectiveness and practicality of the proposed navigation method.
Reddy, A. S. S. R.
This paper attempts to show the relevance of interactive computer graphics in the design of control systems to maintain attitude and shape of large space structures to accomplish the required mission objectives. The typical phases of control system design, starting from the physical model such as modeling the dynamics, modal analysis, and control system design methodology are reviewed and the need of the interactive computer graphics is demonstrated. Typical constituent parts of large space structures such as free-free beams and free-free plates are used to demonstrate the complexity of the control system design and the effectiveness of the interactive computer graphics.
Mazinan, A H; Pasand, M; Soltani, B
In the aspect of further development of investigations in the area of spacecraft modeling and analysis of the control scheme, a new hybrid finite-time robust three-axis cascade attitude control approach is proposed via pulse modulation synthesis. The full quaternion based control approach proposed here is organized in association with both the inner and the outer closed loops. It is shown that the inner closed loop, which consists of the sliding mode finite-time control approach, the pulse width pulse frequency modulator, the control allocation and finally the dynamics of the spacecraft is realized to track the three-axis referenced commands of the angular velocities. The pulse width pulse frequency modulators are in fact employed in the inner closed loop to accommodate the control signals to a number of on-off thrusters, while the control allocation algorithm provides the commanded firing times for the reaction control thrusters in the overactuated spacecraft. Hereinafter, the outer closed loop, which consists of the proportional linear control approach and the kinematics of the spacecraft is correspondingly designed to deal with the attitude angles that are presented by quaternion vector. It should be noted that the main motivation of the present research is to realize a hybrid control method by using linear and nonlinear terms and to provide a reliable and robust control structure, which is able to track time varying three-axis referenced commands. Subsequently, a stability analysis is presented to verify the performance of the overall proposed cascade attitude control approach. To prove the effectiveness of the presented approach, a thorough investigation is presented compared to a number of recent corresponding benchmarks. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Full Text Available The collocation method is extended to the special orthogonal group SO(3 with application to optimal attitude control (OAC of a rigid body. A left-invariant rigid-body attitude dynamical model on SO(3 is established. For the left invariance of the attitude configuration equation in body-fixed frame, a geometrically exact numerical method on SO(3, referred to as the geometric collocation method, is proposed by deriving the equivalent Lie algebra equation in so(3 of the left-invariant configuration equation. When compared with the general Gauss pseudo-spectral method, the explicit RKMK, and Lie group variational integrator having the same order and stepsize in numerical tests for evolving a free-floating rigid-body attitude dynamics, the proposed method is higher in accuracy, time performance, and structural conservativeness. In addition, the numerical method is applied to solve a constrained OAC problem on SO(3. The optimal control problem is transcribed into a nonlinear programming problem, in which the equivalent Lie algebra equation is being considered as the defect constraints instead of the configuration equation. The transcription method is coordinate-free and does not need chart switching or special handling of singularities. More importantly, with the numerical advantage of the geometric collocation method, the proposed OAC method may generate satisfying convergence rate.
Zhu, Jing; Wang, Xingshu; Wang, Jun; Dai, Dongkai; Xiong, Hao
Deflections of the vertical (DOV) are normally ignored in the gravity compensation procedure, which become one of the primary error sources in inertial navigation. In a single-axis rotation INS/GPS system, bias of the gyro and the accelerometer can be ignored, the attitude error is mainly affected by DOV. In this paper, the ideal system assumption is abandoned and the influence of DOV on the attitude is comprehensively discussed, which can be divided into two parts i.e. the direct influence and the indirect influence. The attitude error tracks the DOV along the trajectory belongs to the former. A relatively fixed delay between the attitude error and the DOV belongs to the latter. The delay is essentially induced by the weak observability of the system to the violent DOV. Factors which affect the delay are carefully analyzed. The simulation results show that the delay is mainly affected by accuracies of the inertial sensors and the GPS. It decreases with the GPS accuracy increasing, but increases with the inertial sensor accuracy increasing. The process noise covariance matrix Q plays an important role. With analysis of the characteristics of the delay, influence of the DOV on attitude is studied further, which is necessary for the attitude correction in future.
Full Text Available Despite being entirely preventable, canine rabies still kills 55,000 people/year in developing countries. Information about local beliefs and practices can identify knowledge gaps that may affect prevention practices and lead to unnecessary deaths.We investigated knowledge, attitudes and practices related to rabies and its prevention and control amongst a cross-section of households (n = 5,141 in urban and rural areas of central, southern and northern Tanzania. Over 17% of respondents owned domestic dogs (average of 2.3 dogs/household,>95% had heard about rabies, and>80% knew that rabies is transmitted through dog bites. People who (1 had greater education, (2 originated from areas with a history of rabies interventions, (3 had experienced exposure by a suspect rabid animal, (4 were male and (5 owned dogs were more likely to have greater knowledge about the disease. Around 80% of respondents would seek hospital treatment after a suspect bite, but only 5% were aware of the need for prompt wound cleansing after a bite. Although>65% of respondents knew of dog vaccination as a means to control rabies, only 51% vaccinated their dogs. Determinants of dog vaccination included (1 being a male-headed household, (2 presence of children, (3 low economic status, (4 residing in urban areas, (5 owning livestock, (6 originating from areas with rabies interventions and (7 having purchased a dog. The majority of dog-owning respondents were willing to contribute no more than US$0.31 towards veterinary services.We identified important knowledge gaps related to, and factors influencing the prevention and control of rabies in Tanzania. Increasing knowledge regarding wound washing, seeking post-exposure prophylaxis and the need to vaccinate dogs are likely to result in more effective prevention of rabies; however, greater engagement of the veterinary and medical sectors is also needed to ensure the availability of preventative services.
Luna, Michael E.; Collins, Stephen M.
On November 4, 2010 the already "in-flight" Deep Impact spacecraft flew within 700km of comet 103P/Hartley 2 as part of its extended mission EPOXI, the 5th time to date any spacecraft visited a comet. In 2005, the spacecraft had previously imaged a probe impact comet Tempel 1. The EPOXI flyby marked the first time in history that two comets were explored with the same instruments on a re-used spacecraft-with hardware and software originally designed and optimized for a different mission. This made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby. As part of the spacecraft team preparations, the ADCS team had to perform thorough sequence reviews, key spacecraft activities and onboard calibrations. These activities included: review of background sequences for the initial conditions vector, sun sensor coefficients, and reaction wheel assembly (RWA) de-saturations; design and execution of 10 trajectory correction maneuvers; science calibration of the two telescope instruments; a flight demonstration of the fastest turns conducted by the spacecraft between Earth and comet point; and assessment of RWA health (given RWA problems on other spacecraft).
Luna, Michael E.; Collins, Steven M.
On November 4, 2010 the former "Deep Impact" spacecraft, renamed "EPOXI" for its extended mission, flew within 700km of comet 103P/Hartley 2. In July 2005, the spacecraft had previously imaged a probe impact of comet Tempel 1. The EPOXI flyby was the fifth close encounter of a spacecraft with a comet nucleus and marked the first time in history that two comet nuclei were imaged at close range with the same suite of onboard science instruments. This challenging objective made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby.As part of the spacecraft flyby preparations, the ADCS operations team had to perform meticulous sequence reviews, implement complex spacecraft engineering and science activities and perform numerous onboard calibrations. ADCS contributions included design and execution of 10 trajectory correction maneuvers, the science calibration of the two telescopic instruments, an in-flight demonstration of high-rate turns between Earth and comet point, and an ongoing assessment of reaction wheel health. The ADCS team was also responsible for command sequences that included updates to the onboard ephemeris and sun sensor coefficients and implementation of reaction wheel assembly (RWA) de-saturations.
Eling, C.; Klingbeil, L.; Wieland, M.; Kuhlmann, H.
In many unmanned aerial vehicle (UAV) applications a direct georeferencing is required. The reason can be that the UAV flies autonomous and must be navigated precisely, or that the UAV performs a remote sensing operation, where the position of the camera has to be known at the moment of the recording. In our application, a project called Mapping on Demand, we are motivated by both of these reasons. The goal of this project is to develop a lightweight autonomously flying UAV that is able to identify and measure inaccessible three-dimensional objects by use of visual information. Due to payload and space limitations, precise position and attitude determination of micro- and mini-sized UAVs is very challenging. The limitations do not only affect the onboard computing capacity, but they are also noticeable when choosing the georeferencing sensors. In this article, we will present a new developed onboard direct georeferencing system which is real-time capable, applicable for lightweight UAVs and provides very precise results (position accuracy σ < 5 cm and attitude accuracy σ < 0.5 deg). In this system GPS, inertial sensors, magnetic field sensors, a barometer as well as stereo video cameras are used as georeferencing sensors. We will describe the hardware development and will go into details of the implemented software. In this context especially the RTK-GPS software and the concept of the attitude determination by use of inertial sensors, magnetic field sensors as well as an onboard GPS baseline will be highlighted. Finally, results of first field tests as well as an outlook on further developments will conclude this contribution.
Toldbod, Thomas; Israelsen, Poul
Through an empirical case study this article examines the operation of multiple management control systems as a package in a Danish manufacturing company. The analysis focuses on four different management control systems; cybernetic controls, planning controls, reward controls, and administrative...... controls, through the theoretical lens of globalization, localization, and glocalization. The analysis documents that these different management control systems are affected differently by the processes of globalization and localization, whereby some are universal throughout the organization and others...... have more particular characteristics. Specifically, this study finds that cybernetic controls and administrative controls are designed as global management control systems. Planning controls are glocal systems and reward & compensation controls assume local characteristics. The finding leads...
Smith, S. F. (Inventor)
A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.
Full Text Available Apilot survey using a structured questionnaire was conducted in Tororo and Busia districts of Uganda on the knowledge and attitudes of cattle owners regarding tsetse fly and trypanosomosis control, in order to understand factors that hindered their full participation. A total of 81 cattle owners was randomly selected and interviewed, of which 92.5 % were aware of tsetse flies and trypanosomosis and 87.6%recognised animal trypanosomosis as a problem in the area. Most cattle owners were aware of tsetse fly trapping (76.5 %, isometamidium chloride use (55.5 %, diminazene aceturate use (48 % and pour-on applications (18.5 %. However, knowledge did not coincide with the application of control measures. Despite the widespread awareness, tsetse fly trapping and pour-on applications were used by only a small percentage of cattle owners (7.5 % applied tsetse fly trapping while 76.5%were aware of it; 1.2%applied pour-oninsecticides while 18.5%were aware of them. Differences between awareness and application were highly significant for tsetse fly trapping (c2=67.8, d.f.=1, P<0.001 and pour-on applications (c2=10.8, d.f.=1, P<0.05, but not for isometamidium chloride use (c2 = 0.08, d.f. = 1, P = 0.77 and diminazene aceturate use (c2 = 0.00, d.f. = 1, P = 1.00. Most cattle owners (97.5 % were willing to participate in future control programmes, but preferred participating on a group basis (85.2 % rather than individually (14.8 %. The 4 most favoured control options in order of importance were: fly traps supplied by the government and maintained by cattle owners; contribution of labour by cattle owners for trap deployment; self-financing of trypanocidal drugs and self-financing of pour-on insecticide. The control options that should be selected in order to elicit full participation by cattle owners are discussed.
H Samsul Bachri
Full Text Available A good controller system must have resilience to disturbance and must be able to response quickly and accurately. Problem usually appears when PID controller system was built sensitively hence the system's respon to the disturbance will yield big overshot/undershot then the possibility of oscillation to be happened is excelsior. When the controller system was built insensitively, the overshot/undershot will be small but the recovery time will be longer. Hybrid controller system could overcome those problems by combining PID control system with fuzzy logic. The main control of this system is PID controller while the fuzzy logic acts to reduce an overshot/undershot and a recovery time. The fuzzy logic controller is designed with two input error and delta error and one output of the motor speed. The output of fuzzy logic controller should be only half of the PID controller for limiting entirely fuzzy output. This hybrid system design has a better respon time controller system than PID controller without fuzzy logic.
Full Text Available Noncooperative target spacecrafts are those assets in orbit that cannot convey any information about their states (position, attitude, and velocities or facilitate rendezvous and docking/berthing (RVD/B process. Designing a guidance, navigation, and control (GNC module for the chaser in a RVD/B mission with noncooperative target should be inevitably solved for on-orbit servicing technologies. The proximity operations and the guidance for achieving rendezvous problems are addressed in this paper. The out-of-plane maneuvers of proximity operations are explored with distinct subphases, including a chaser far approach in the target’s orbit to the first hold point and a closer approach to the final berthing location. Accordingly, guidance solutions are chosen for each subphase from the standard Hill based Closhessy-Willtshire (CW solution, elliptical fly-around, and Glideslope algorithms. The control is based on a linear quadratic regulator approach (LQR. At the final berthing location, attitude tracker based on a proportional derivative (PD form is tested to synchronize the chaser and target attitudes. The paper analyzes the performance of both controllers in terms of the tracking ability and the robustness. Finally, it prescribes any restrictions that may be imposed on the guidance during any subphase which can help to improve the controllers tracking ability.
Martin E. Cobern
The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the testing of the rebuilt laboratory prototype and its conversion into a version that will be operable in the drilling tests at TerraTek Laboratories. In addition, formations for use in these tests were designed and constructed, and a test protocol was developed. The change in scope and no-cost extension of Phase II to January, 2006, described in our last report, were approved. The tests are scheduled to be run during the week of January 23, and should be completed before the end of the month.
Hansen, Poul Erik; Conrad, Finn
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...... to hinder surges and mechanical fractures. Experimental results verify the performance of the controllers....
Leva, Alberto; Papadopoulos, AV; Terraneo, F
This book argues that computer operating system components should be conceived from the outset as controllers, synthesised and assessed in the system-theoretical world of dynamic models, and then realised as control algorithms.
Design of fault handling in control systems is discussed, and a method for consistent design is presented.......Design of fault handling in control systems is discussed, and a method for consistent design is presented....
Campbell, Charles E. (Inventor)
In the absence of a gyroscope, the attitude and attitude rate of a receiver can be determined using signals received by antennae on the receiver. Based on the signals received by the antennae, the Doppler difference between the signals is calculated. The Doppler difference may then be used to determine the attitude rate. With signals received from two signal sources by three antennae pairs, the three-dimensional attitude rate is determined.
Shafiei, Seyed Ehsan; Rasmussen, Henrik; Stoustrup, Jakob
This paper proposes a model predictive control scheme to provide temperature set-points to thermostatic controlled cooling units in refrigeration systems. The control problem is formulated as a convex programming problem to minimize the overall operating cost of the system. The foodstuff...
In this paper, we propose methodology to solve noninteracting control problem for general nonlinear systems based on the relaxed control technique proposed by Artstein. For a class of nonlinear systems which cannot be stabilized by smooth feedback, a state-feedback relaxed control can be designed to
Hansen, Knud Bent; Skaarup, Per
A description is given of the principles of a digital system used to control neutron spectrometers. The system is composed of independent functional units with the control programme stored on punched paper tape or in a computer.......A description is given of the principles of a digital system used to control neutron spectrometers. The system is composed of independent functional units with the control programme stored on punched paper tape or in a computer....
This report examines in detail the control and information system requirements of the St. Lawrence Seaway development program in terms of the needs of the vessel traffic controllers and the management users. Structural control models of Seaway operat...
Progress in Controlled Gastroretentive Delivery Systems. ... Abstract. Controlled release (CR) dosage forms have been extensively used to improve therapy with several important drugs. However, the ... Keywords: Gastroretention, Oral controlled release, Swelling, Narrow absorption window, Floating dosage form. Tropical ...
Engel, Joshua Allen
The Environmental Control System provides a controlled air purge to Orion and SLS. The ECS performs this function by processing 100% ambient air while simultaneously controlling temperature, pressure, humidity, cleanliness and purge distribution.
Full Text Available Paper presents a methodology for design of integrated fuzzy logic based an expert controller and its implementation for a real time oven temperature control system. Integrated expert controller (IEC is composed by cascading fuzzy logic controller with improved PID controller. Wherein, fuzzy controller evaluates the supplemental control actions and PID evaluates the final control actions. Temperature measurement of the oven with a precision of 16-bits is achieved through Pt100, instrumentation amplifier, and A/D converter and fuzzy plus PID computed control actions are given to the actuator via D/A converter (16-bits and PWM generator. Paper experimentally demonstrated the performance of IEC for oven temperature control application. The performance indexes of the system are presented in a comparative fashion with the conventional PID and expert controllers. Control algorithms are developed using C language.