Abstract: In order to solve the problem of trajectory tracking and vibration suppression control for parameter unknown flexible-joints space robot system, a joint flexibility compensation controller was introduced to improve the equivalent stiffness of the joint; by using the singular perturbation method, the system was decomposed into a slow subsystem and a fast subsystem. For the slow subsystem, the adaptive fuzzy H∞ control algorithm was designed; by using the fuzzy logic system to approximate the system uncertainty, a robust H∞ control was used to eliminate the influence of the fuzzy approximation legacy of error to the output tracking error. For the fast subsystem, the speed difference between the feedback control law was used to suppress the elastic vibration of flexible joints which was caused by system. Numerical simulation results show that the proposed control algorithm can control the joint tracking of the space robot with flexible joints accurately and steadily, and suppress actively vibration of flexible joints, which proves the validity of the controller.

Key words: flexible-joints space robot, joint flexibility compensation controller, adaptive fuzzy, H∞ robust control