基于位姿可达空间的太空机械臂容错路径规划

为了使太空机械臂在关节锁定故障后仍能继续完成后续任务，提出一种基于位姿可达空间的太空机械臂容错路径规划方法。基于牛顿-拉夫逊法计算太空机械臂关节人为限位，完成满足任务需求的退化工作空间求解，通过构造姿态可达度指标，在退化工作空间的基础上建立故障机械臂基坐标系下的位姿可达空间。通过在代价函数中增加最小奇异值代价项改进传统A^*算法，基于改进A^*算法在所建立的位姿可达空间内完成太空机械臂容错路径规划。所提方法综合了位姿可达空间与改进A^*算法各自的优势，实现了关节锁定故障太空机械臂同时满足避奇异与位姿可达要求的轨迹搜索。通过建立7自由度太空机械臂运动学模型开展数值仿真研究，仿真结果验证了所提容错路径规划方法的有效性。

A fault tolerant path planning method for space manipulator based on position and orientation reachable space

In order that the space manipulator can complete follow-up tasks after the joint-locked failure, a fault tolerant path planning method for the space manipulator is proposed based on position and orientation reachable space. The Newton-Raphson method is used to compute artificial joint limits of the space manipulator, and the degraded workspace that can meet the task requirements is obtained. By constructing orientation reachability indexes, the position and orientation reachable space relative to base calibration is then established. The traditional A^* algorithm is evolved by adding the minimum singular value cost to the evaluation function. In the established position and orientation reachable space, the fault tolerant path planning of the space manipulator is realized by the evolved A^* algorithm. The proposed method, which integrates the advantages of the position and orientation reachable space and the evolved A^* algorithm, realizes trajectory searching of the space manipulator and meet the requirements for singularity avoiding and reachability of position and orientation after the joint-locked failure. A kinematic model for the 7-DOF manipulator is built, and numerical simulation is carried out. Simulation results verify the effectiveness of the proposed method.