Abstract: An adaptive H∞ fault-tolerant vibration-suppressed hybrid control algorithm is proposed for a free-floating flexible space manipulator system with partial loss of control effectiveness (PLCE) fault. Based on the Lagrange method and elastic vibration theory, the dynamic differential equation of the system is deduced, and the first two modes reflecting the main vibration condition of the flexible link are intercepted for vibration analysis. According to the singular perturbation principle, the system is decomposed into a slow-varying subsystem describing the trajectory tracking motions of the rigid arms and a fast-varying subsystem describing the modal vibration of the flexible link. Thus, a hybrid controller composed of an adaptive H∞ fault-tolerant controller of the slow-varying subsystem and a linear optimal vibration-suppressed controller of the fast-varying subsystem is designed. Compared with the traditional fault-tolerant controllers, the adaptive H∞ fault-tolerant controller has the advantage of not requiring prior knowledge of actuator fault. The comparison simulation results show that the fault-tolerant controller of the slow-varying subsystem has strong robustness to the PLCE joint actuator fault, and the linear optimal vibration-suppressed controller of the fast-varying subsystem can adjust the vibration mode of the flexible link to a lower level, which verifies the correctness of the theoretical analysis and the effectiveness of the hybrid control strategy.

Key words: Joint actuator fault, Flexible link, Space manipulator, Fault-tolerant control, Vibration suppression