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The Time Optimal control Problem for a class of Nonholonomic Systems: A Case Study

IFAC Proceedings Volumes 1996年第1期29卷 2325-2329页

作者： Z. Retchkiman F. Khorrami Centro de Investigación en Matemáticas Aplicadas Universidad Autónoma dc Coahuila Campo Redonda Edificio S Apdo. Postal 60-C Saltillo Coahuila México Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering and Computer Science Polytechnic University Six Metrotech Center Brooklyn New York 11201 U.S.A.

The minimum time control problem for a class of non-holonomic controllable nonlinear systems is considered in this paper. These nonlinear systems have drift free dynamics with fewer controls than states. After some review and preliminar results, it is shown, that in general the problem is not solveable. Next, under some restrictions on the control inputs we are able to characterize the zero crossing set and to get solutlOns which result to be of the bang-bang form. Finally, a case study is presented where the proposed solution is compared with other methodologies which solve the point to point motion planning problem, showing that indeed is the best, one can obtain.

关键词： Time optimal control nonholonomic systems singular arc bang bang controls

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EXPERIMENTAL RESULTS ON ADAPTIVE NONLINEAR control AND INPUT PRESHAPING FOR MULTILINK FLEXIBLE MANIPULATORS

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AUTOMATICA 1995年第1期31卷 83-97页

作者： KHORRAMI, F JAIN, S TZES, A School of Electrical Engineering and Computer Science Control/Robotics Research Laboratory (CRRL) Polytechnic University Brooklyn NY 11201 United States Department of Mechanical Engineering Control/Robotics Research Laboratory (CRRL) Polytechnic University Brooklyn NY 11201 United States

Adaptive input precompensators in conjunction with nonlinear controllers for multi-link flexible manipulators are considered in this paper. In an earlier paper, we had shown that application of a nonlinear inner-loop control reduces the variations in frequencies due to the geometrical configuration for multi-link flexible manipulators. This results in a better performance when input preshaping or any other controller based on a linear model is designed. To improve the performance of the system to parameter variations (e.g. changes in payload), an adaptive version of the advocated controller is utilized. This is achieved by estimating the time of application of the impulses for on-line preshaping and in the case of payload uncertainty, estimation of the payload and real-time adjustment of the nonlinear inner-loop based controller. Frequency domain Time-Varying Transfer Function Estimate (TTFE) and Empirical Transfer Function Estimate (ETFE) system identification algorithms are proposed for estimation of vibrational modes and unknown payload. Experimental results on a two-link flexible manipulator with adaptive nonlinear control and preshaping are provided to show the effectiveness of the advocated controllers. Overall, the present paper completely generalizes the adaptive input preshaping technique for multi-link flexible manipulators.

关键词： FLEXIBLE MANIPULATORS VIBRATION DAMPING NONLINEAR control INPUT PRESHAPING IDENTIFICATION ADAPTIVE control

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An adaptive fuzzy neural based controller and its application to smart structures

An adaptive fuzzy neural based controller and its applicatio...

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American control Conference (ACC)

作者： I.J. Zeonoun F. Khorrami CRRL Polytechnic Univ. Brooklyn NY USA Control Robotacs Research Laboratory CRRL School of Electrical Engineering Computer Science Six Metrotech Center Polytechnic University Brooklyn NY USA

This paper introduces a fuzzy neural based adaptive controller for simultaneous stabilization and robust performance of a family of plants. The family of plants may be attained from linearization of a nonlinear plant around different operating points or large parameter variations in a given plant. The main idea is to design a sequence of controllers corresponding to the different plants utilizing any standard control design. Thereafter, the obtained controllers will form the basis of the knowledge base of a fuzzy controller capable of deriving a desired crisp output through its inference engine. A neural network is utilized to derive a fuzzy model of the plant and to generate the rule base for the fuzzy logic controller through training. The effectiveness of this new scheme is verified on a smart structure with piezoceramic sensors and actuators.

关键词： Programmable control Adaptive control Fuzzy control Intelligent structures Fuzzy logic Robust control control design Engines Neural networks Fuzzy neural networks

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Adaptive control of flexible-link manipulators with piezoelectric ceramic sensors and actuators 1

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IFAC Proceedings Volumes 1994年第14期27卷 593-598页

作者： Farshad Khorrami Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering & Computer Science Polytechnic University Six Metrotech Center Brooklyn NY 11201

Active control of flexible multi-body systems and structures through utilization of smart materials is considered in this paper. Specifically, utilization of piezoceramics for sensing and actuation is investigated. Experimental setups have been developed at crrl to study modeling issues and control design approaches for flexible structures with embedded (or surface-mounted) piezoceramics. In this paper, experimental results on vibration suppression for a flexible manipulator with surface mounted piezoceramics are presented. It will be shown that piezoceramics substantially improve the performance of the systems under consideration. The advocated approaches for control designs are decentralized frequency shaping and self-tuning adaptive controllers. The self-tuning controller is based on identification of the system dynamics in frequency domain utilizing Fast Fourier Transform (FFT). Addition of a self-tuning regulator enhances the performance and the robustness of the controlled system to parameter variations.

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Vibration suppression of unknown flexible payloads using a wrist mounted force/torque sensor for remote manipulator systems

Vibration suppression of unknown flexible payloads using a w...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： S. Jain F. Khorrami Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering & Computer Science Five Metrotech Center Polytechnic University Brooklyn NY USA

The problem of control design for robotic arms manipulating unknown flexible payloads is considered. control design based on neglecting the internal dynamics of the payload will result in degraded performance, increased task execution time, and even failure in performing tasks. At the same time, the characteristics of payloads to be handled vary with application. These considerations make it impractical to outfit the payload with sensors. A novel scheme utilizing a force/torque sensor at the wrist of the manipulator is introduced. A controller utilizing the wrist torque feedback from the sensor is designed as a function of parameters of the payload dynamics. An adaptive scheme for online identification of these parameters and adaptation of controller parameters is discussed. The scheme is implemented on a single-link manipulator carrying a flexible unknown payload. Experimental results validate the fact that the adaptive control maintains a robust performance for high speed slewing and varying payloads.< >

关键词： Payloads Wrist Sensor phenomena and characterization control design Manipulator dynamics Adaptive control Robots Arm Degradation Force sensors

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Utilization of torque wheels for active damping of flexible manipulators

Utilization of torque wheels for active damping of flexible ...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： F. Khorrami A.A. Gomez M.D. Hills Polytechnic University School of Electrical Engineering 4 Computer Science Control/Robotics Research Laboratory Brooklyn NY USA Bernoulli Optical Systems Company Danbury CT USA Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering 4 Computer Science University of California Brooklyn NY USA

Utilization of inertial actuators, such as torque wheels, for vibration damping of a single-link flexible manipulator is considered. The torque wheel is mounted at the end effector of the manipulator to provide a bending moment at the tip for vibration suppression and pointing purposes. The torque exerted by the torque wheel at the end-effector of the manipulator is achieved through controlling the velocity of the torque wheel. A decentralized control scheme is advocated in this paper for slewing and vibration suppression. The local loop around the torque wheel is closed through feedback of the accelerometer signal at the tip. Experimental results are provided to show the effectiveness of the proposed method for end-effector positioning of flexible-link manipulators. Although the experimental results reported are for a single-link flexible manipulator, the results are applicable to the multi-link case. It may be shown that the dynamics from the voltage input to the torque wheel mounted at the tip to the tip position is minimum phase and hence invertible given that an inner-loop controller has been applied to stabilize the rigid-body motion.< >

关键词： Wheels Damping Torque control Manipulator dynamics Actuators End effectors Velocity control Distributed control Vibration control Feedback loop

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Fuzzy based adaptive control for flexible-link manipulators actuated by piezoceramics

Fuzzy based adaptive control for flexible-link manipulators ...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： I. Zeinoun F. Khorrami Sch. of Electr. Eng. & Comput. Sci. Polytechnic Univ. Brooklyn NY USA Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering & Computer Science Six Metrotech Center Polytechnic University Brooklyn NY USA

This paper presents an adaptive control scheme based on a fuzzy logic algorithm and its application to end-effector positioning of flexible-link manipulators. Here, a fuzzy based adaptive controller is considered due to its simplicity and the fact that it does not require expressing the controller in terms of the system parameters, as it is necessary in the case of self-tuning regulators. This controller is based on a functional fuzzy model where the consequents are crisp functions represent controllers designed for different operating regimes. The premise is constituted by the fuzzy subsets corresponding to the process parameters estimated in real time. The effectiveness of this new scheme is verified on a clamped free beam and a single-line flexible arm instrumented with piezoceramic sensors and actuators. It is shown that robust performance may be achieved in face of large parameter variations.< >

关键词： Fuzzy control Adaptive control control systems Fuzzy logic Fuzzy systems Programmable control Parameter estimation Instruments Piezoelectric materials Actuators

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Adaptive nonlinear excitation control of power systems with unknown interconnections

Adaptive nonlinear excitation control of power systems with ...

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IEEE Conference on Decision and control

作者： S. Jain F. Khorrami Control/Robotics Research Laboratory (CRRL) School of Electrical Engineering & Computer Science Polytechnical University Brooklyn NY USA

Adaptive nonlinear excitation control of large-scale power systems is considered in this paper. The approach used is an adaptive feedback linearizing control to enhance the robustness to unknown or varying interconnection parameters like equivalent reactances of the transmission lines. Adaptation in estimated parameters is utilized to achieve an asymptotically exact cancellation of terms. Simulation results for a two generator-infinite bus power system are presented to validate the robustness of the adaptive feedback linearizing scheme to unknown interconnections arising due to faults and subsequent line switchings. The performance using the nonadaptive feedback linearizing control is shown to degrade for network configuration variations arising due to transmission line faults. The studies validate the fact that connective stability and robust performance is maintained for unknown interconnection topology using the adaptive feedback linearizing scheme.< >

关键词： Power system control Programmable control Adaptive control Nonlinear control systems control systems Power systems Power system interconnection Power system simulation Linear feedback control systems Power transmission lines

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Non-Linear control with End-Point Acceleration Feedback for a Two-Link Flexible Manipulator: Experimental Results

Non-Linear Control with End-Point Acceleration Feedback for ...

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American control Conference (ACC)

作者： Farshad Khorrami Sandeep Jain Control/Robotics Research Laboratory School of Electrical Engineering & Computer Science Polytechnic University Brooklyn NY USA

In this paper, experimental results for a two-stage controller comprised of a rigid-body based nonlinear control augmented with a linear dynamic output feedback derived from Youla's parameterization of stabilizing controllers are presented for a two-link flexible arm at crrl. It is shown that the outer-loop controller enhances vibration damping and robustness of the closed-loop dynamics to parameter variations.

关键词： Acceleration Linear feedback control systems Output feedback Payloads Vibration control Robust control Accelerometers Hydraulic actuators PD control control systems

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