Trajectory Tracking Control Of Wheeled Mobile Robot Under Disturbance Environment

In recent years,wheeled mobile robots(WMRs)have been applied extensively in many fields,for instance,industry,agriculture,family,transportation,military and other fields.Therefore,the development and research of WMRs are great importance in the field of automation.And trajectory tracking control is critical to realize the autonomous movement of WMRs.Hence,the accurate trajectory tracking control of the WMRs is a prerequisite to complete complex tasks.However,in the actual environment,the WMRs are faced with many problems,such as the difficulty in establishing accurate model,non-linear model,non-holonomic constraints,internal and external interferences,and the difficulty in controlling complex trajectory,which all pose great challenges to its work.Good trajectory tracking control technology can make it achieve fast,stable and safe working effect in the actual working environment.Therefore,the trajectory tracking control problem of WMRs was studied deeply in this paper.Firstly,the trajectory tracking control problem of WMRs,which are subjected to non-random and random disturbances,is studied.Considering the linear dynamics model,the Kalman filter with a disturbance observer is designed to estimate the non-random disturbances and states,and the random disturbances are processed..According to the observation information,a double closed-loop integral sliding mode controller is designed.Based on the Lyapunov stability theory,the stability and convergence of the double closed-loop systems are analyzed theoretically.Simulation results show the effectiveness of the algorithm.Secondly,on the basis of the previous chapter,the non-linear dynamics model is studied.The extended Kalman filter with a disturbance observer is used to estimate the state and non-random disturbance and the random disturbances are processed.Based on the observation information,an error feedback controller and a kinematics controller are designed for the velocity loop and the position loop,respectively.The stability and convergence of the control strategy are proved through theoretical analysis.Simulation results of straight line and circle demonstrate the effectiveness of the algorithm.And then,in order to solve the problem of error convergence time in trajectory tracking control of WMRs in disturbed environment,two sets of control schemes,namely double closed-loop finite time control strategy and double closed-loop fixed time control strategy are designed.In the polar coordinates of WMRs,kinematics model is established.Firstly,a corresponding finite time extended state observer and fixed time extended state observer are designed to estimate the external disturbances.And then based on the integral nonsingular terminal sliding mode control,the double closed-loop finite time controller and double closed-loop fixed time controller are designed,respectively.The stabilities of the proposed two sets of double closed-loop control systems are proved by designing Lyapunov Functions,and the convergence time is obtained.Finally,the performances of the two control schemes are compared and verified by numerical simulation.Last,considering the problem of optimal control index of WMRs with disturbance,a double closed-loop trajectory tracking control strategy is proposed,which combines position loop self-adaption integral sliding mode control with velocity loop feedforward and feedback optimal control.Baesd on the fixed time control theory,the improved non-linear extended state observer is designed to estimate the external disturbance and internal uncertainty of the system and observations are compensated to the controller.Also,the stability of the double closed-loop system and the iterative feasibility of the algorithm are analyzed theoretically.The simulation results show the effectiveness and robustness of the algorithm.