State Observer Based Robust Backstepping Fault-Tolerant Control of the Free-Floating Flexible-Joint Space Manipulator

Actuator failure and joint flexibility will dramatically impact space robot system control. In this paper, free-floating flexible-joint space-manipulator dynamic-modeling is studied a state-observer-based robust backstepping fault-tolerant control proposed for the actuator failure. Based on simplified model, system’s rigid-flexible coupled-dynamic equations are established according to momentum conservation, angular Lagrange equation. Then decoupled based singular perturbation method. For slow subsystem, controller base state observer designed eliminate angle error, compensate uncertain parameter external disturbance, achieve joint-trajectory asymptotic-tracking. The use of speed filter makes it inappropriate measure provide feedback about velocity signals, so simpler more precise. fast differential-feedback adopted suppress vibration caused by flexible joint, ensure stability system. Finally, feasibility effectiveness model method proved some simulations. simulation results indicate that can make manipulator track desired trajectory accurately steadily, regardless whether fails or not.