保持基座稳定的双臂空间机器人轨迹规划研究

针对双臂空间机器人在轨执行任务中需要利用平衡臂稳定基座的问题, 提出了两种典型应用需求——基座质心位置稳定、基座姿态和质心位置同时稳定的协调规划方法.首 先,提出了“系统质心等效机械臂”的概念并推导其运动学模型,基于此模型的位置级反解规 划平衡臂的运动轨迹,使基座质心位置稳定在期望位置;其次,根据角动量守恒定律确定反作用飞 轮的运动速度,将飞轮与平衡臂的运动相结合,同时稳定基座姿态和质心位置;最后,建立双臂空间机器人系统的多体动力学模型并开展仿真研究.所提出的方法克服了以往基于微分运动学所无法回避的奇异问题,且不对平衡臂的质量特性和安装位置作特殊规定,仿真结果证明了方法的有效性.

Study on Trajectory Planning of Dual-arm Space Robot Keeping the Base Stabilized

Aiming at the case that the base is required to be stabilized by a balance arm while a dual-arm space robotic system performing on-orbit missions, we propose coordinated trajectory planning methods of two typical applications——keeping the base centroid fixed (approximately; the same below); keeping the base attitude and centroid position fixed synchronously. Firstly, the concept of "system centroid equivalent manipulator" is presented, and its kinematic model is derived. Based on the resolution of the position-level kenematic equation, the trajectory of the balance arm for stabilizing the base centroid is planned. Secondly, combining with the control of a reaction flywheel, the base attitude and centroid can be kept fixed at the same time. The desired angular speed of the flywheel is determined according to the angular momentum conservation law. Finally, the multi-body dynamic model of a dual-arm space robotic system is developed and simulation study is carried out. The proposed methods overcome the singularity problem which is un-avoidable for previous approaches based on differential kinematics. Furthermore, there are not special requirements on the mass properties and installation position of the balance arm. Simulation results verify the proposed methods.