Adaptive Contact Force Control of a Flexible Beam Using Output Feedback

2000 ◽  
Author(s):  
Woosoon Yim
Keyword(s):  
Contact Force ◽  
Contact Surface ◽  
Force Control ◽  
Closed Loop ◽  
Force Measurement ◽  
Transient Behavior ◽  
Loop System ◽  
Flexible Beam ◽  
Reference Trajectory ◽  
Closed Loop System

Abstract This paper presents an adaptive force trajectory control of a flexible beam using a piezoceramic actuator. Based on the adaptive backstepping method, a force control system using only force measurement is designed. For the derivation of the control law, it is assumed that parameters of the beam and contact surface stiffness are unknown. It is shown that in the closed-loop system, the contact force tracks a given reference trajectory and the beam vibration is suppressed as well. Digital simulations results show that the closed-loop system has good transient behavior and robust performance in the presence of uncertainties in the parameters of the flexible beam and the contact surface.

OUTPUT FEEDBACK ADAPTIVE VARIABLE STRUCTURE CONTROL OF CHAOS IN LORENZ SYSTEM

2002 ◽  
Vol 12 (03) ◽  
pp. 571-582 ◽  
Author(s):  
ALDAYR D. ARAUJO ◽  
SAHJENDRA N. SINGH
Keyword(s):  
Closed Loop ◽  
Lorenz System ◽  
Digital Simulation ◽  
Variable Structure ◽  
Transient Behavior ◽  
Loop System ◽  
Reference Trajectory ◽  
Closed Loop System ◽  
Output Variable ◽  
Control Of Chaos

Based on the variable structure model reference adaptive control (VS-MRAC) theory, a new control system for the control of chaos in Lorenz system, using only the measured output variable, is designed. For the derivation of the control law, it is assumed that the parameters of the model are unknown. Moreover, it is assumed that a disturbance input is present in the system. It is shown that in the closed-loop system, the output variable tracks a given reference trajectory, and the state vector converges to the equilibrium state. Digital simulation results show that the closed-loop system has good transient behavior and robustness to the uncertainties and disturbance input.

Application of Anytime Control to an Inherently Unstable Physical System

2015 ◽  
Author(s):  
Wayne Maxwell ◽  
Al Ferri ◽  
Bonnie Ferri
Keyword(s):  
Closed Loop ◽  
Initial Conditions ◽  
Transient Behavior ◽  
Open Loop ◽  
Loop System ◽  
Closed Loop System ◽  
Pendulum System ◽  
Inverted Pendulum System ◽  
Lqr Controller ◽  
Two Stages

This paper extends the use of closed-loop anytime control to systems that are inherently unstable in the open-loop. Previous work has shown that anytime control is very effective in compensating for occasional missed deadlines in the computer processor. When misses occur, the control law is truncated or partially executed. However, the previous work assumed that the open-loop system was stable. In this paper, the anytime strategy is applied to an inverted pendulum system. An LQR controller with estimated state feedback is designed and decomposed into two stages. Both stages are implemented most of the time, but in a small percentage of time, only the first stage is applied, with the resulting closed-loop system being unstable for short periods of time. The statistical performance of the closed-loop system is studied using Monte-Carlo simulations. It is seen that, on average, the closed-loop performance is very close to that of the full-order controller as long as the miss rate is relatively small. However, the variance of the response shows much higher dependence on the miss rate, suggesting that the response becomes more unpredictable. At a critical value of miss rate, the closed-loop system is unstable. The critical miss rate found through simulation is seen to correlate well with the results of a deterministic stability analysis. The statistics on the settling time are also studied, and shown to grow longer as the miss rate increases. The transient behavior of the system is studied for a range of initial conditions.

On the control of a single flexible arm robot via Youla-Kucera parameterization

Robotica ◽  
2014 ◽  
Vol 34 (1) ◽  
pp. 150-172 ◽  
Author(s):  
Habib Esfandiar ◽  
Saeed Daneshmand ◽  
Roozbeh Dargahi Kermani
Keyword(s):  
Closed Loop ◽  
Optimization Techniques ◽  
Loop System ◽  
Flexible Manipulator ◽  
Order System ◽  
Flexible Beam ◽  
Closed Loop System ◽  
Stabilizing Controller ◽  
Main Challenge ◽  
Tip Mass

SUMMARYIn this paper, based on the Youla-Kucera (Y-K) parameterization, the control of a flexible beam acting as a flexible robotic manipulator is investigated. The method of Youla parameterization is the simple solution and proper method for describing the collection of all controllers that stabilize the closed-loop system. This collection comprises function of the Youla parameter which can be any proper transfer function that is stable. The main challenge in this approach is to obtain a Youla parameter with infinite dimension. This parameter is approximated by a subspace with finite dimensions, which makes the problem tractable. It is required to be generated from a finite number of bases within that space and the considered system can be approximated by an expansion of the orthonormal bases such as FIR, Laguerre, Kautz and generalized bases. To calculate the coefficients for each basis, it is necessary to define the problem in the form of an optimization problem that is solved by optimization techniques. The Linear Quadratic Regulator (LQR) optimization tool is employed in order to optimize the controller gains. The main aim in controller design is to merge the closed-loop system and the second order system with the desirable time response characteristic. The results of the Youla stabilizing controller for a planar flexible manipulator with lumped tip mass indicate that the proposed method is very efficient and robust for the time-continuous instances.

Position/force control of robot manipulators using reinforcement learning

2019 ◽  
Vol 46 (2) ◽  
pp. 267-280 ◽  
Author(s):  
Adolfo Perrusquía ◽  
Wen Yu ◽  
Alberto Soria
Keyword(s):  
Reinforcement Learning ◽  
Force Control ◽  
Closed Loop ◽  
Position Error ◽  
Loop System ◽  
Closed Loop System ◽  
Content Type ◽  
Impedance Model ◽  
Impedance Parameters ◽  
The Stability

Purpose The position/force control of the robot needs the parameters of the impedance model and generates the desired position from the contact force in the environment. When the environment is unknown, learning algorithms are needed to estimate both the desired force and the parameters of the impedance model. Design/methodology/approach In this paper, the authors use reinforcement learning to learn only the desired force, then they use proportional-integral-derivative admittance control to generate the desired position. The results of the experiment are presented to verify their approach. Findings The position error is minimized without knowing the environment or the impedance parameters. Another advantage of this simplified position/force control is that the transformation of the Cartesian space to the joint space by inverse kinematics is avoided by the feedback control mechanism. The stability of the closed-loop system is proven. Originality/value The position error is minimized without knowing the environment or the impedance parameters. The stability of the closed-loop system is proven.

Adaptive Output Feedback Force Control of a Cantilever Beam Using a Piezoelectric Actuator

2003 ◽  
Vol 9 (5) ◽  
pp. 567-581 ◽  
Author(s):  
W. Yim ◽  
S. N. Singh
Keyword(s):  
Force Control ◽  
Output Feedback ◽  
Force Measurement ◽  
High Gain ◽  
Flexible Beam ◽  
Closed Loop System ◽  
Inverse Control ◽  
Piezoceramic Actuator ◽  
Beam Parameters ◽  
Contact Force Control

In this paper, we treat the question of force control and stabilization of a flexible beam using a piezoceramic actuator using only output feedback. It is assumed that there are unstructured model uncertainties, including the beam parameters, the contact surface stiffness, and the number of vibration modes in the model, and only force measurement is used for the contact force control. The controller has the structure of an inverse (a feedback linearizing) control system. In order to compensate for the unknown function in the inverse control law arising from the uncertainties in the model, its estimate is constructed by a high-gain observer. Simulation results are presented which show robust force trajectory control and stabilization in the closed-loop system in the presence of unstructured uncertainties. Furthermore, it is observed that stability and trajectory tracking are preserved in the presence of measurement noise.

Active Vibration Control of Beams by Combining Precompressed Layer Damping and ACLD Treatment: Performance Comparison of Various Robust Control Techniques

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Rajiv Kumar
Keyword(s):  
Robust Control ◽  
Closed Loop ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Performance Comparison ◽  
Loop System ◽  
Flexible Beam ◽  
Closed Loop System ◽  
Linear Quadratic ◽  
System Parameters

It is a well known fact that system parameters of the flexible structures keep on changing due to several reasons. Ordinary controllers lose their effectiveness in changed situations and do not guarantee the stability of the closed loop system. However, controllers designed based on robust control theory not only maintain the closed loop stability of the perturbed system with a large variation in system parameters but also maintain the best performance. H∞ loop shaping controller is designed and implemented experimentally on a smart flexible beam treated with precompressed layer damping and ACLD treatment. It outperforms linear quadratic Gaussian and standard H∞ controller both in terms of robust stability and robust performance. Relative merits and demerits of the μ-synthesis based controller are also discussed. Afterwards, these controllers were digitized at certain sampling frequencies and applied to the experimental flexible structure. Certain time domain parameters of the closed loop system discuss the relative superiority of these controllers which otherwise cannot be captured using frequency domain results alone.

Robust Output Feedback Force Control of Cantilever Beam Using Piezoelectric Actuator

2001 ◽  
Author(s):  
Woosoon Yim ◽  
Sahjendra N. Singh
Keyword(s):  
Force Control ◽  
Output Feedback ◽  
Force Measurement ◽  
High Gain ◽  
Flexible Beam ◽  
Closed Loop System ◽  
Inverse Control ◽  
Piezoceramic Actuator ◽  
Beam Parameters ◽  
Contact Force Control

Abstract This paper treats the question of force control and stabilization of a flexible beam using a piezoceramic actuator using only output feedback. It is assumed that there exists unstructured model uncertainties including beam parameters, contact surface stiffness, and the number of vibration modes in the model, and only force measurement is used for the contact force control. The controller has the structure of an inverse (a feedback linearizing) control system. For compensating the unknown function in the inverse control law arising from the uncertainties in the model, its estimate is constructed by a high-gain observer. Simulation results are presented which show robust force trajectory control and stabilization in the closed-loop system in the presence of unstructured uncertainties.

Adaptive Control of a Smart Projectile Fin With Unknown High-Frequency Gain by Piezoelectric Actuation

2007 ◽  
Author(s):  
Venkat Mudupu ◽  
Sahjendra Singh ◽  
Woosoon Yim
Keyword(s):  
Adaptive Control ◽  
Control System ◽  
High Frequency ◽  
Closed Loop ◽  
Aerodynamic Force ◽  
Angular Rate ◽  
Loop System ◽  
Reference Trajectory ◽  
Piezoelectric Bimorph ◽  
Closed Loop System

This paper delves into adaptive control of a smart projectile fin with unknown high frequency gain using a piezoelectric bimorph. The hollow projectile smart fin is actuated using a cantilevered piezoelectric bimorph that is completely enclosed within the fin. The model of the smart fin system includes the aerodynamic moment which is a function of the angle of attack of the projectile. The rotation angle of the fin is controlled by deforming the piezoelectric bimorph which is hinged at the tip of the rigid fin. It is assumed that fin parameters as well as the high frequency gain of the model are unknown. Moreover, the model includes an unknown bounded time varying aerodynamic disturbance. An adaptive control system using the Nussbaum gain is designed. The structure of the control system is independent of the dimension of the flexible fin model. This is important because the fin model has large number of flexible modes. For the design of the control law, a linear combination of the fin angle and fin angular rate is chosen as the controlled output variable. In the closed loop system, all the signals are bounded and the fin angle tracks the reference trajectory. Simulation results are presented along with the experimental validation done using the subsonic wind tunnel at the University of Nevada, Las Vegas (UNLV). Both simulation and experimental results show that in the closed-loop system, the fin angle is precisely controlled in spite of the uncertainties in the fin parameters and the aerodynamic force.

Adaptive Servoregulation of a Projectile Fin Using Piezoelectric Actuator

Aerospace ◽  
2005 ◽  
Author(s):  
Smitha Mani ◽  
Sahjendra N. Singh ◽  
Surya Kiran Parimi ◽  
Woosoon Yim
Keyword(s):  
Piezoelectric Actuator ◽  
Closed Loop ◽  
Angular Rate ◽  
Adaptive Controller ◽  
Loop System ◽  
Laboratory Model ◽  
Flexible Beam ◽  
Closed Loop System ◽  
Real Time Control ◽  
Aerodynamic Moment

This paper treats the question of adaptive control of a projectile fin using a piezoelectric actuator. The hollow projectile fin is rigid, within which a flexible cantilever beam with a piezoelectric active layer is mounted. The model of the fin-beam system includes the aerodynamic moment which is a function of angle of attack of the projectile. The rotation angle of the fin is controlled by deforming the flexible beam which is hinged at the tip of the rigid fin. It is assumed that the system parameters are completely unknown and that only the fin angle and its derivative are measured for synthesis. A linear combination of the fin angle and fin’s angular rate is chosen as the controlled output variable and an adaptive servoregulator is designed for the control of the fin angle and the rejection of the disturbance input (aerodynamic moment). In the closed-loop system, the fin angle asymptotically converges to the desired value and the elastic modes converges to their equilibrium values. Computer simulation is performed which shows that in the closed-loop system, the fin angle is precisely controlled in spite of uncertainties in the fin-beam parameters and the aerodynamic moment coefficients. Furthermore, a laboratory model of the projectile fin is developed and the adaptive controller is implemented for real-time control. Experimental results are presented which show that adaptive servoregulator accomplishes fin angle control.

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