Abstract:
The dynamic modeling, the motion control and flexible vibration suppression of a free-floating space robot with flexible-joints, bounded torques, external disturbances and uncertain parameters are discussed. The dynamic equation of the system is established by using the Lagrange equation and the linear and angular momentum conservations of the system. Based on singular perturbation theory, the system is decomposed into a slow subsystem and a fast subsystem. For the slow subsystem, a robust fuzzy sliding mode controller based on hyperbolic sine functions is designed. The controller does not need to know the accurate system model. It can compensate the system rotation angle errors caused by the flexible-joints and can realize the desired motion trajectories asymptotic tracking. The hyperbolic sine functions can reduce the control the amplitude of torques effectively, which makes the control system more realistic. For the fast subsystem, a velocity difference feedback controller is used to suppress the vibration caused by flexible-joints and thus guarantees the system’s stability. The simulation results prove the proposed hybrid controller’s efficiency.