Sensorless Contact Force Sensing and Compliant Docking for Active Impact Docking Mechanism

The active impact docking mechanism (AIDM) has become a research hot spot in the aerospace field due to its efficient docking capability and significant potential for in-orbit reuse. However, the performance of its force sensors is challenging to ensure in complex space environments. To address this, this article proposes a contact force estimation method for AIDM. The method proceeds as follows: first, initial force estimation is performed using the dynamic model of AIDM and real-time current data; then, frictional forces are fitted based on the Stribeck model to enhance estimation accuracy, and estimation noise is mitigated through a Kalman filter; finally, a force estimation module (FEM) is constructed. In addition, this study employed a location-based variable impedance strategy, which enables dynamic adjustment of impedance parameters. The validity of the proposed FEM and variable impedance control framework is verified through experiments. Experimental results demonstrate that the force estimation accuracy of FEM exceeds 8%, and the torque estimation accuracy exceeds 12%. The variable impedance control ensures the smooth completion of compliant docking tasks for AIDM. Compared with constant impedance control, both docking time and contact force are improved.