Impedance joint torque control of an active-passive composited driving self-adaptive end effector for space manipulator

An active-passive composited driving self-adaptive end effector is proposed for the space manipulator, that is a two-finger gripper with an active motor and a passive spring. The problems of dynamics and control are challenging because of the strong coupling and their heavy computational burdens for the implementation of model-based control algorithms. To avoid solving differential-algebraic equations, the Virtual Spring Approach (VSA) is presented for formulating the appropriate dynamics model. Next, the impedance joint torque controller is proposed to control the system dynamics of capturing because the finger appears as active mechanical impedance with variable impedance parameters when it makes contact with an unknown object. Finally, the simulation results validate the self-adaptability of the active-passive composited driving end effector, and the proposed control scheme is adequate.