Optimization of the End-Effector Trajectory to Suppress the Attitude Variation and Reduce Impulsive Force Simultaneously at Capturing a Target

Abstract

This paper is devoted to optimize the trajectory of the end-effector of space robot to suppress the attitude variation of the main body and to reduce impulsive force at capturing a target as well as to preserve the manipulability during manipulator motions. The B spline curve is applied to represent the trajectory shape. Constrained parameters of the manipulation include relative velocities and attitude between the target and the end-effector and the approach direction to the target at the capture. The knot vectors and control points of the curve at the end of the trajectory are determined to meet the constraints. By discretizing states variables, the problem is formulated as the non-linear optimization problem. The optimal trajectories for five approach directions are obtained by using Sequential Quadratic Programming (SQP) method. Effect of difference of the approaching direction on the manipulability, impulsive forces, attitude variation and optimal trajectory is investigated, and a basic strategy for planning the end-effector trajectory is discussed to conclude the present result of study.