Equivalent kinematics and pose-configuration planning of segmented hyper-redundant space manipulators

Abstract

With multiple segments and associated universal joints, a segmented hyper-redundant manipulator can perform on-orbital servicing tasks in confined space due to its superior flexibility and dexterity. However, its inverse kinematics resolving and trajectory planning are challenging because of special structure and strict environment constraints. In this paper, we propose an equivalent kinematics modelling and pose-configuration simultaneous planning method to perform given missions with high efficiency. First, a kinematic equivalence arm (KEA) with revolution joints is constructed by rearranging the associated universal joints of each segment. The motion of n associated universal joints in each segment is simplified as that of a serial arm composed of 1 Roll and n coplanar Yaw joints. The endpoint pose (position and orientation) of the KEA is the same as that of each segment; its shape is also easily described as the Roll angle and the normal vector of the configuration plane. Correspondingly, the kinematics of the whole manipulator composed of N segments is modeled as the combined kinematics of N KEAs. Here KEAs is denoted as the kinematic equivalence model of the proposed manipulator. Then, its configuration represented by KEAs' shape parameters and end-effector's pose are planned simultaneously according to the environment constraints. Finally, trajectory tracking and narrow space detection task are simulated and experimented respectively. The results of trajectory tracking show that the computation time of the proposed method is greatly reduced. The simulation and experiment results of narrow space detection verify the proposed method.