Multiobjective preimpact trajectory planning of space manipulator for self-assembling a heavy payload

Yong Liu,Zhe Du,Xiaojun Li,Zhe Wu,Fei Liu

doi:10.1177/1729881421990285

Abstract

To assemble a heavy payload to the spacecraft (free-floating base), the present study proposes a scheme of multiobjective trajectory planning for preimpact motion of redundant space manipulator (mounted on the base). Force impulse for self-assembly is derived as the function of joint angles/velocities, base pose, and impact direction. The trajectory planning problem is formulated as multiobjective optimization to minimize force impulse, base attitude disturbance, and energy consumption in the load-carrying process. A two-stage trajectory planning algorithm is proposed. To be specific, at the first stage, multiple desired configurations at the contact point are generated by position-level inverse kinematics with Newton–Raphson iterative method. At the second stage, joint trajectories satisfying joint angle limits and desired motion of the payload are parameterized by coefficients of sinusoidal polynomial functions. Multiobjective particle swarm optimization algorithm is adopted to solve the problem of multiobjective trajectory planning, and screening process is conducted to reserve nondominated solutions in limits of joint torques. The algorithm is implemented to a seven degrees of freedom space manipulator, and the effectiveness of the proposed method is verified by simulation results.

Highlights

Space manipulators are increasingly critical to future on-orbit servicing,[1] especially to capture, assemble, and maintain large-space structures.[2]
For the dynamic coupling effect between space manipulator and spacecraft,[3] attitude disturbance of the base induced by heavy payload should be considered in the motion planning process
Given the significance of on-orbit assembling a heavy payload to free-floating base with a space manipulator, the present study proposes a scheme of multiobjective preimpact trajectory planning

Summary

Introduction

Space manipulators are increasingly critical to future on-orbit servicing,[1] especially to capture, assemble, and maintain large-space structures.[2] After capturing a heavy payload, the space manipulator mounted on the spacecraft base is employed to assemble payload to the base. Space manipulator should carry the payload from capture pose (including position and orientation) to preassembly pose. For the dynamic coupling effect between space manipulator and spacecraft,[3] attitude disturbance of the base induced by heavy payload should be considered in the motion planning process. Impact problem has not been considered in the mentioned studies

Objectives

Results

Conclusion