Adaptive Switching Iterative Learning Control Of Free-floating Space Robot

With the unprecedented rapid development of human space technology,various activities in space become more and more frequent.This greatly promotes the technology research of space robots that can replace astronauts for Extravehicular operations.However,a series of uncertain factors such as fuel consumption,load unknown,external disturbance and system parameter change exist in the space robot operating in the space environment.At the same time,considering the flexible factors of the space robot,such as the base elastic and the flexible joint,can not be ignored in the reality.Under the background of this research,aiming at the uncertain problems of the system,such as internal parameter changes,external disturbances and load changes,a self-adaptive switching iterative learning controller based on saturation function is designed for trajectory tracking control of space robot system.Firstly,the modeling of space robot is carried out.By using Lagrange equation and momentum conservation,the system dynamics and kinematics equations of rigid single arm space robot are discussed.In view of the joint flexibility problem,the dynamic equation of a flexible joint space robot is derived by using the hypothetical modal method.For the problem of base elasticity,we use the second kinds of Lagrange equations and the law of conservation of momentum to derive the dynamic equations of the floating space robot system under the influence of base elasticity.The research content will provide a theoretical basis for the subsequent design of the control scheme.Secondly,considering the boundary problem of unknown parameters,a self-adaptive iterative learning controller based on saturation function is designed for rigid single arm space robot,and the tracking control of manipulator's joint angle is realized.Furthermore,according to the load change,changes in system parameters and external disturbances of rigid arm space robot uncertainty,designed a learning controller based on adaptive switching iterative saturation function,and control,to the position of the carrier attitude controlled the situation to achieve a trajectory tracking control.In addition,a hybrid control scheme based on saturation function,adaptive iterative learning control and speed feedback,is designed for trajectory tracking control of joint robots.Finally,an adaptive iterative learning controller based on saturation function is designed for the floating base space robot under the influence of the base elasticity.Since there is no active restraint on the elastic vibration of the base,it can be seen from the example of inertia space simulation that the elastic vibration of the base is serious,and it has a certain influence on the end trajectory tracking.To solve this problem,an adaptive iterative learning control based on saturation function and an active vibration suppression control for base vibration are designed.This composite control scheme not only meets the accuracy requirement of trajectory tracking,but also suppresses the elastic vibration of the base.In order to solve these problems,this paper studies the adaptive switched iterative learning control scheme based on the saturation function.The results of MATLAB numerical simulation prove that the scheme is effective and feasible.