Research On Trajectory Tracking For Robotic Manipulators Based On Sliding Mode Control

In recent years,robotic control has become one of the research hotspot in academic community due to its important role in industrial manufacturing,deep-sea exploration and aerospace.In this thesis,the trajectory tracking control of the n-joint rigid robotic manipulators system is studied by combining the non-singular terminal sliding mode,adaptive technique and finitetime stability theory.The main works of this paper are summarized as follows:(1)Based on non-singular terminal sliding mode,the tracking of the reference trajectory is realized for n-joints rigid robotic manipulators system with uncertainties and disturbances.At first,a novel non-singular terminal sliding mode surface is proposed which contains arctan function(ATNTSM).Then,a ATNTSM control law is designed to guarantee that the system states in rigid robotic manipulators system converge to zero in finite time.Additionally,the control law is modified by virtue of substituting saturation function for sign function in control law,which forms continuous control law and vanishes chattering phenomenon.In the end,an illustration of two-joints robotic manipulators is provided to demonstrate the effectiveness of the proposed algorithm.(2)An adaptive chattering-free fast non-singular terminal sliding mode control approach is proposed for the robotic manipulators system with deadzone.In order to ensure that the system states can converge to origin in finite time,a chattering-free fast non-singular terminal sliding mode controller is designed.Then,continuous control signals are obtained by means of replacing sign(·)with sat(·)in the control law,and resulting in the elimination of chattering.Considering external disturbances and parameter uncertainties exist in practical system,the adaptive technique is introduced to compensate them.Finally,simulation results validate the effectiveness of the proposed control approach.(3)Aiming at n-joints rigid robotic manipulators with uncertainties such as parameter perturbation,external torque disturbance and nonlinear friction,a control method is proposed by means of using high-order sliding mode observer approach.Firstly,considering the angular velocity of each joint is unmeasurable,a high-order sliding mode observer is designed to observe the angular velocity signals of the robotic manipulators system.In addition,a fast non-singular terminal sliding mode surface is constructed by using the observed states,and a fast non-singular terminal sliding mode controller is designed by means of finite-time stability theory.Finally,based on the Lyapunov function,it's proved that the trajectory tracking errors of the robotic manipulators system can converge to zero in a finite time,and the numerical simulations are carried out to verify the effectiveness of the scheme.