Research On Sliding Mode Control Method Of Manipulator Based On Disturbance Observer

Because of the progress of science and technology and the advancement of modern manufacturing,the manipulator industry has also flourished and has been applied in industrial production,medical treatment,aerospace,agriculture,and other fields.The manipulator is a nonlinear system with strong coupling and complexity,and there are uncertainties,thus the control of the manipulator is challenging.In order to ensure that the manipulator system carries out efficient and reliable work,this paper designs controllers for the manipulator system with complex uncertainties,combines the techniques of sliding mode control,disturbance observer,and adaptive control,and carries out the research on the trajectory tracking control strategy of the manipulator.The concrete research works are given.(1)On account of the trajectory tracking control issue of the manipulator with disturbances,a fractional-order non-singular fast terminal sliding mode controller is presented.Above all,the fractional-order non-singular fast terminal sliding mode surface is proposed so that the system state completes fast convergence in finite time.The reaching law is proposed based on the super-twisting algorithm,thus weakening the chattering in the system.In the meantime,a nonlinear disturbance observer is designed to perform accurate estimation of the magnitude of external disturbances for the purpose of compensation of the controller,and further increase the control accuracy of the system.Ultimately,the proof of controller stability is given.Simulation experiments are conducted with a two-joint manipulator as the research object,and the results testify the feasibility and stability of the presented controller.(2)Considering the external disturbances in the manipulator system,a fractional-order non-singular fast terminal sliding mode controller based on a fixed-time disturbance observer is raised.Design a fractional-order non-singular fast terminal sliding mode surface so as to accelerate the convergence of the system state in the sliding phase.A variable exponential power reaching law is raised,which can adaptively change the motion speed in line with the current position of the system state,then boost the robustness of the controller.Furthermore,a fixed-time sliding mode disturbance observer is given to solve the external disturbances and to compensate the system by real-time estimation.In line with the theory of Lyapunov function,the stability of the system is certified.Using simulation experiments,it is demonstrated that the raised controller has excellent anti-interference property and can accomplish effective tracking of the manipulator trajectory.(3)Considering the uncertain information such as external disturbances and model errors in the manipulator system,an adaptive fractional-order sliding mode controller based on a fixed-time disturbance observer is presented.Foremost,the fractional-order non-singular fast terminal sliding mode surface is given.In line with the super-twisting algorithm,an adaptive reaching law is raised,which ensures the control performance of the full sliding mode control phase.Simultaneously,on account of the compound disturbance existing in the manipulator system,an adaptive fixed-time sliding mode disturbance observer is raised to deal with the matter,which can estimate the lumped disturbance in real-time.Moreover,compensate for the system and enhance the precision of the controller.The finite-time convergence properties of the observer and the stability of the system are certified in the light of Lyapunov stability theory.Ultimately,simulation experiments are conducted to verify the conspicuous performance of the presented controller.