Singularity-free path planning of dual-arm space robot for keeping the base inertially stabilized during target capturing

Compared with a single-arm space robot, a dual-arm or multi-arm system has much more dexterity and flexibility, and can complete more complex tasks. In this paper, oordinated path planning methods are proposed for a dual-arm space robotic system to capture a target and stabilize the base at the same time. Two typical applications are considered - keeping the centroid of the base fixed (approximately; the same below), and keeping the pose (attitude and the centroid position) of the base fixed synchronously. Firstly, the concept “Base Centroid Virtual Manipulator” is presented, and its kinematic model is directed. Based on the resolution of the position-level kinematic equation, the motion of the balance arm for stabilize the base´s centroid is planned. Furthermore, combining with the control of reaction flywheel, whose angular speed is determined according to the angular momentum conservation law, the base´s attitude and centroid can be kept fixed at the same time. The proposed methods overcome the singularity problem, which is un-avoidable for those based on differential kinematics.