Friction identification and control for Chinese large-scale space end-effector´s dragging subsystem

In order to achieve large tolerance capture and high stiffness connection for space payload operations, a Chinese large-scale space end-effector (EER) was developed. Friction is a kind of strong nonlinear factor that severely degrades performance of EER. To predict the friction amplitude and compensate the dynamic error, the friction model based Generalized Maxwell-Slip model (GMS) is built. In order to improve the parameters identification accuracy of friction model, and overcome the error effects of the low speed velocity measurement, the full-order speed observer is designed as feedback speed information. Experiments platform has been built and some dragging experiments on the EER have been done. Results of the experiments show that the precision of the position tracking can reach ±0.02mm by GMS compensation, increased more than 30% compared with Stribeck friction model.