Research On Low Speed Motion Optimization Of Space Manipulator

With in-depth space exploration and rapid development of space technology,the space task becomes increasingly complex,which puts forward high requests to the safety and operation accuracy of the space manipulator.Low-speed crawling phenomenon may occur when space manipulators complete space operating missions in a low speed,which may seriously affect the operation accuracy of space manipulators.What's worse,it may lead to missions failing.Therefore it is with great significance to do research on low speed motion optimization of space manipulator.In order to improve the low speed performance of space manipulators,this paper will focus on motion optimization in two low speed operation modes:transferring without load and carrying heavy load,which includes the following parts:Firstly,the low speed motion performance of space manipulators and its influencing factors are studied.The low speed mathematical model of space manipulator considering each influencing factor respectively is established.And the influencing evaluation index of low speed motion performance is put forward.Then for two operation modes,the influence evaluation index is calculated based on the same trajectory planning respectively.Through comparative analysis of the results obtained above,the primary influencing factor affecting the low speed motion performance of space manipulators is obtained.Secondly,the low speed motion optimization method of space manipulators without load based on gradient projection method is studied.Aimed at that the low speed crawling problem of space manipulators is mainly caused by nonlinear joint friction,the low speed motion optimization objective of space manipulator without load is established.Then a continuous balanced proportional factor is proposed,and the stable region of that is calculated.The initial configuration of space manipulator is obtained based on New-Raphson iteration.In the end of this part,the low speed motion optimization of space manipulator is completed by introducing the motion optimization parameter,and the correctness and effectiveness are confirmed by simulations.Finally,the low speed multi-objective optimization method of space manipulators with heavy load is studied.Aimed at the problem that the low speed crawling of space manipulators is mainly caused by link flexibility,the multi-objective optimization model of space manipulator with heavy load is established,and the constraint equations and the objective functions are established yet.The joint trajectories are interpolated by a sinusoidal function,whose argument is a sixth-order polynomial,of which the control parameters are used as the decision variables of multi-objective optimization.At last,multi-objective particle swarm optimization algorithm is improved by introducing the random velocity operator,Gauss operator and chaos operator,and the multi-objective optimization is completed,the correctness and effectiveness of which are confirmed by simulations.