Modeling and Analysis of Force-Closure Properties for the Flexible Space Manipulator During Docking and Capturing Process

To acquire the rapid numerical simulation iteration with sufficient precision for the space manipulator, and resolve the contradiction between the force-closure properties elimination and vibration suppression, a parametric modelling method for the flexible space manipulator system was proposed in this paper. Based on this method and by adopting the Adams software, a rigid-flexible dynamic model for the space manipulator applying in the space station was developed, which contained the cabin, adapter and end-effector. Especially, the flexibility of the manipulator was introduced by employing the modal superposition method. Also, the stiffnesses of the harmonic reducer and torque sensor were respected in order to simulate the flexibility of manipulator joints. Then a typical working task represented as shifting the load module by using the space manipulator was selected to analyze its dynamic behavior during the docking and capturing process. Results showed that the joint error could be reduced by the flexibility deformation of the space manipulator. And it was found the contact force and joint load were positively related with joints stiffness. In general, the modeling method and dynamic model proposed in this paper could provide a reference for the design and operation setting for the space manipulator.