Variable structure control of a robot arm with flexible links

The authors treat the question of the control of an elastic, two-link robotic arm using variable structure system (VSS) theory and the pole assignment technique for stabilization. A discontinuous joint angle control law that accomplishes asymptotic decoupled joint-angle-trajectory tracking is designed. In the closed-loop system, the trajectories are attracted toward a chosen hypersurface in the state space and then slide along it. Although joint angles are controlled using a variable structure control (VSC) law, the flexible modes of the links are excited. Starting with a linearized model of the terminal state, a stabilizer is designed using the pole assignment technique to control the elastic oscillation of the links. A control logic is included to switch the stabilizer the instant the joint angle trajectory enters a specified neighborhood of the terminal state. Simulation results show that the closed-loop system can achieve accurate trajectory tracking and elastic mode stabilization.<<ETX>>

[1]  Rangasami L. Kashyap,et al.  Pseudolinks and the self-tuning control of a nonrigid link mechanism , 1988, IEEE Trans. Syst. Man Cybern..

[2]  R. H. Cannon,et al.  Initial Experiments on the End-Point Control of a Flexible One-Link Robot , 1984 .

[3]  Patrizio Tomei,et al.  Model reference adaptive control algorithms for industrial robots , 1984, Autom..

[4]  T. Fukuda.  Flexibility control of elastic robotic arms , 1985 .

[5]  S. Sastry,et al.  A calculus for computing Filippov's differential inclusion with application to the variable structure control of robot manipulators , 1987 .

[6]  Control of a flexible robot arm , 1989, Proceedings of the 28th IEEE Conference on Decision and Control,.

[7]  Sahjendra Singh,et al.  Elastic Robot Control: Nonlinear Inversion and Linear Stabilization , 1986, IEEE Transactions on Aerospace and Electronic Systems.

[8]  A. Galip Ulsoy,et al.  Control of a Flexible Robot Arm: Experimental and Theoretical , 1987 .

[9]  Sahjendra N. Singh,et al.  Dual Mode Control of an Elastic Robotic Arm: Nonlinear Inversion and Stabilization by Pole Assignment , 1989, 1989 American Control Conference.

[10]  Aldo Balestrino,et al.  Nonlinear adaptive model-following control , 1984, Autom..

[11]  Toshio Fukuda,et al.  Flexibility control of elastic robotic arms and its application to contouring control , 1984, ICRA.

[12]  Fumitoshi Matsuno,et al.  Modeling and feedback control of a flexible arm , 1985, J. Field Robotics.

[13]  Wayne J. Book,et al.  Feedback control of two beam, two joint systems with distributed flexibility , 1975 .

[14]  S. N. Singh,et al.  Control and stabilization of nonlinear uncertain elastic robotic arm , 1988 .

[15]  Sahjendra N. Singh,et al.  Control of Elastic Robotic Systems by Nonlinear Inversion and Modal Damping , 1986 .

[16]  J. J. Slotine,et al.  Tracking control of non-linear systems using sliding surfaces with application to robot manipulators , 1983, 1983 American Control Conference.

[17]  Vadim I. Utkin,et al.  Sliding Modes and their Application in Variable Structure Systems , 1978 .