Whole-body compliance for multi-arm space robotic capturing of large tumbling target in connection compliant phase

Based on the characteristics of large tumbling space debris, this article proposes an effective method for whole-body compliant controller to eliminate the effects of the relative velocity between chaser and target which is not zero after the capture hands hold their corresponding handles tightly that is named as connection compliant phase. First, the kinematics and dynamics models are established, including tumbling target, free-floating chaser and chaser–target, respectively. Second, to analyse the characteristics of capturing of a large tumbling target, a simplified kinematics model about the centre of mass of the chaser is established, and a Cartesian-space compliant controller is designed in order to achieve the desired gross force as the input of multi-arm compliant distribution. Subsequently, we propose a method based on centre of forces to distribute the desired gross force to each arm optimized first and also a closed-loop regulator based on the dissipation vectors online as the second step. Then, a passivity-based control strategy is used in order to enhance the robustness of the system. Finally, the effectiveness of the control strategy mentioned above is verified by the simulation and air-bearing experiment in the horizontal plane partially.