Impedance control in serial-parallel hybrid space robots for assembly operations

This article presents the impedance control method for a serial-parallel hybrid space robot system (HSRS) including a robotic arm and a parallel platform in Stewart configuration, and achieves compliance and stability during assembly operations. In this article, the dynamic model of the HSRS is established firstly with considering the influence of external forces, which is the foundation of subsequent research. Afterwards, the impedance control method of the HSRS is implemented by analyzing its dynamic coupling effect. Based on that, the compliance assembly operation is achieved by the coordination between the robotic arm and the parallel platform. The correctness of the HSRS dynamic model is demonstrated through the theorem of momentum and closed-chain constraint equations. The effectiveness of the impedance control method is verified through a simulation of modules assembly. Moreover, the operational abilities of traditional serial space robot and the HSRS are compared by introducing external disturbances. Simulation results show the efficiency of the HSRS.