This paper presents a trajectory optimization and control approach for the guidance of an orbital four-arm robot in extravehicular activities. The robot operates near the target spacecraft, enabling its arm's end-effectors to reach the spacecraft's surface. Connections to the target spacecraft can be established by the arms through specific footholds (docking devices). The trajectory optimization allows the robot path planning by computing the docking positions on the target spacecraft surface, along with their timing, the arm trajectories, the six degrees of freedom body motion, and the necessary contact forces during docking. In addition, the paper introduces a controller designed to track the planned trajectories derived from the solution of the nonlinear programming problem. A weighted controller formulated as a convex optimization problem is proposed. The controller is defined as the optimization of an objective function that allows the system to perform a set of tasks simultaneously. Simulation results show the application of the trajectory optimization and control approaches to an on-orbit servicing scenario.

翻译：本文提出了一种用于舱外活动中轨道四臂机器人引导的轨迹优化与控制方法。该机器人在目标航天器附近运行，使其机械臂末端执行器能够抵达航天器表面。机械臂可通过特定立足点（对接装置）与目标航天器建立连接。轨迹优化通过计算目标航天器表面的对接位置及其时序、机械臂轨迹、六自由度本体运动以及对接过程中的必要接触力，实现机器人路径规划。此外，本文设计了一种用于跟踪非线性规划问题解所导出规划轨迹的控制器，提出了一种表述为凸优化问题的加权控制器。该控制器定义为目标函数的优化，使系统能够同时执行多组任务。仿真结果表明了轨迹优化与控制方法在在轨服务场景中的应用。