Force and Moment Compensation Method Based on Three Degree-of-Freedom Stiffness-Damping Identification for Manipulator Docking Hardware-In-The-Loop Simulation System

The space manipulator docking hardware-in-the-loop (HIL) simulation system is an important means to simulate the real space docking on the ground. In this paper, a space manipulator docking HIL system is designed, the space manipulator docking dynamics model is established and the motion process of space docking is simulated by a six degree-of-freedom (DOF) parallel robot. Delays exist in the force sensor and the parallel robot of the HIL system and are unavoidable; which not only affect the accuracy of the HIL system simulation, but also lead to instability of the system, resulting in docking failure and damage to the docking mechanism (DM). In view of the contact characteristics of DM, a force and moment compensation method based on three DOF stiffness-damping identification is proposed in this paper. Considering the time-varying characteristics of multi-DOF contact parameters, on-line identification is applied to identify the stiffness and damping in three perpendicular directions. Then a six DOF compensation model is established to compensate the deviation of contact force and moment caused by the delays, so as to improve the stability and reproduction accuracy of the system. Compared with the existing single DOF compensation researches, the considering of contact parameters and the model of compensation in this paper are all applicable to multi-DOF system. Moreover, the compensation model doesn't need the model and delay characteristics of the parallel robot, so it is a model-free compensation. The effectiveness of the proposed compensation method is verified by simulation and experiment.