Fuzzy Robust Sliding Mode Control and Flexible Vibration Active Suppression of Flexible-joint Space Robot Based on Flexibility Compensation

For free-floating flexible-joint space robot system with uncertain parameters, the dynamics modeling, motion controller design and flexible vibration active suppression are developed. Dynamic equations of the system are established by the system's linear and angular momentum conservation and Lagrange equation. In order to overcome the limitations of that the traditional singular perturbation method only applies to the system with weak joint flexibility, a joint flexibility compensator is designed to improve the flexible-joint's stiffness of space robot system equivalently. On the above basis, the system is decomposed into a slow subsystem and a fast subsystem by singular perturbation method, and the controllers of the subsystems are designed. The slow subsystem's fuzzy robust sliding mode controller can compensate the uncertain parameters, decrease the rotation angle transmission errors caused by the flexible-joint, and realize the asymptotic tracking of the system desired trajectory. The fast subsystem controller can suppress the flexible vibration caused by flexible-joint actively. The simulation experimental results prove the efficiency of the hybrid controller.