Control of Elastic Robotic Systems by Nonlinear Inversion and Modal Damping

Abstract

Energy efficient, lightweight robot arms for space applications have considerable structural flexibility. For large and fast motions, both the nonlinear coupled dynamics and the elastic behavior of the robots must be considered in control system designs. This paper presents an approach to the control of a class of flexible robotic systems. A control law is derived which decouples the joint-angle motion from the flexible motion and asymptotically decomposes the elastic dynamics into two sub-systems, representing the transverse vibrations of the elastic link in two orthogonal planes. This decomposition allows the design of an elastic mode stabilizer independently based on lower order models representing structural flexibility. The closed-loop system is shown to be globally asymptotically stable and robust to uncertainty in system parameters. Simulation results are presented to show that large, fast control of joint angles can be performed in spite of space vehicle motion and uncertainty in the payload.

Novel Adaptive PID Control of Flexible Joint Robot Manipulator withBounded Disturbances

“…Adopting the robust PID adaptive control law described in (7)(8)(9)(10) and (32)(33)(34) to simulate the tracking effects of robot manipulator, the simulation results can be seen from Figures 2,3,4,5, and 6. These figures indicate that the robust adaptive PID control scheme can compensate the bounded external disturbances and guarantee the manipulator systems to track the desired position and velocity trajectories accurately with quit small tracking errors in finite time.…”

“…The control of robot faces significant difficulties, with regard to such a complicated system, various controllers have been developed [1], such as adaptive controllers [2][3][4], robust controllers [5][6][7] and controllers based on the theory of variable structure [8][9][10][11]. However, the applicability of these controllers to practical robot is limited because the assumption of perfect rigidity is never satisfied exactly.…”

Dual mode inverse control and stabilization of flexible space robots

“…Based on perturbation approach [9,10] and Lyapunov stability theory, controllers have been designed in [7,8,11,12] for space robots. Nonlinear inversion technique has been applied in [13,14] for the space robots, however, control of the spacecraft has not been considered in these. Singular perturbation method has been used to develop continuous path tracking control system for free-flying space robots [15].…”

Control of Trajectory Kinematics for Flexible Manipulators Applying Integral Variable Structure Strategy

“…Such a case is a highly nonlinear system with complicated coupled dynamics and uncertainty (various load, inertia, and gravitational forces etc.). With regard to such a complicated system, various controllers have been developed [1], such as adaptive controllers [2][3][4], robust controllers [5][6][7] and controllers based on the theory of variable structure [8][9][10][11]. However, the applicability of these controllers to practical robot is limited because the assumption of perfect rigidity is never satisfied exactly.…”