An Observer-Based Stiffness Estimation for Space Target Capture by Space Robot with Controllable Damping Mechanism

The space target capturing task using the spacecraft-manipulator system (SMS) has special significance in on-orbit servicing due to its theoretical challenges and practical value. contact force between end effector (gripper) exerted by tumbling motion of destabilizes spacecraft base. A full-dimensional controllable damping mechanism (FDCDM) with a cross-axis structure was designed buffer transient impact on joint. introduction gives robot variable stiffness system, estimation algorithm is proposed calibrate stiffness, as cannot be measured directly. equivalent four-DOF tandem joint, whole-body dynamic model SMS endowed established Kane equation. Then, an unknown input observer (UIO)-based identification theory precisely estimate internal flexibility torque corresponding joint stiffness. model-based neural learning update parameter matrix observer. simulation experiment results demonstrate that could accurately estimated within expected error, illustrating feasibility effectiveness method.