Abstract:

：The robust control based on observers is proposed for a free-floating flexible space manipulator. Firstly the interactions of flexible motion of the two flexible links are decoupled by choosing appropriate local coordinate frame; the dynamic model of a free-floating two-flexible-links space manipulator is established by the Lagrange equations and the momentum conservation. Secondly singular perturbation model of the space flexible manipulator system is obtained by using two-time scale control theory, in which the system is decoupled into slow (rigid) and fast (flexible) subsystems. Then an observer based robust composite controller which consists of a slow control component and a fast control component is proposed. A sliding velocity observer based robust control algorithm is applied to control the slow subsystem to track the desired trajectory. The fast controller is designed with the estimated velocity by a linear state observer to damp out the vibration of the flexible links using optimal Linear Quadratic Regulator (LQR) method. Finally the numerical simulation is carried out, which demonstrates the controller proposed is feasible and effective.

Key words: linear observer, robust control, singular perturbation approach, sliding observer, free-floating two-flexible-links space manipulator