Fast Sliding Mode Control Research Of Free-floating Space Robot Which Is Based On The Fuzzy Reaching Law

With the continuous development of science and technology,the development and utilization of space resources has aroused the attention of all countries.In the hard space environment,the cost and risk to complete the task by astronauts is high,therefore,the research of space robot has caused the attention of researchers.Free-floating space robot is a nonlinear,strong coupling and time-varying system and its control technology is rather complex.Chattering has some influence on the service life of the space robot,it is particularly important for a reasonable control method to make its convergence speed and chattering both achieve the ideal effect in the process of trajectory tracking control of space robot.Based on the above background,fast sliding mode control scheme of the free-floating space robot by chattering suppression is studied by the article.First of all,the design of vehicle location of free-floating space robot is uncontrolled to reduce the consumption of liquid fuel.Carrier needs to maintain a certain attitude angle so as to meet the demand of normal work.Therefore,free-floating space robot system of position-uncontrolled and attitude-controlled,as the research object,is studied.By using the Lagrange Equations of the second kind,the dynamic equations of free-floating space robot system with rigid single arm,dual-arm floating-space robot system with rigid double arms and free-floating space robot system with flexible manipulators are built.By the location and geometry relations of the space robot and the principle of conservation of system momentum,the relationship of Jacobi of the mechanical arm system is built,and the kinematics and dynamics characteristics of the system are found out.Then,for the problem of convergence rate and chattering suppression in the process of trajectory tracking control,it designs a method of fast sliding mode variable structure control which is based on the fuzzy exponential reaching law.It puts forward a fast nonlinear sliding mode surface,which is faster than the speed of the traditional sliding mode surface,achieves effective results.According to the principle of fuzzy control,it designs a fuzzy exponential reaching law,which makes the buffeting suppression effect of the mechanical arm obvious,and guarantees the effect of trajectory tracking control of the system.According to the Lyapunov Stability Theorem,the space robot systems with single-arm,dual-arms and flexible manipulators are calculated,and it verifies the stability and convergence of the system.Finally,the space robot system is very complex,which has many uncertain factors such as load changing,friction and random disturbance,so it is difficult to get the accurate model in the actual circumstances.In ideal situation,by the numerical simulation experiment of the system,it verities the proposed control method of all the space robot systems.The numerical simulation results prove the feasibility and effectiveness of the proposed control scheme.