Research On Trajectory Tracking Control Of Wheeled Mobile Robot Based On Model Predictive Control

Wheeled mobile robots have a wide range of application value.Therefore,more and more researchers have carried out deep studies on them.The wheeled mobile robots work in a complex environment.Then they are vulnerable to external interference,control constraints and many other factors,which makes the trajectory tracking control more difficult.In order to solve the above problems,a model predictive control method is introduced to study the trajectory tracking control of wheeled mobile robot system in depth.Firstly,considering that wheeled mobile robots are constrained by control quantity and control increment,a trajectory tracking control strategy of linear model predictive control with soft constraints is designed.In addition,stability of the wheeled mobile robot system is proved by theoretical analysis.Validity of the algorithm is verified by a double line change trajectory test and a circle simulation.Secondly,a nonlinear model predictive control is proposed to achieve the trajectory tracking control due to non-linearity of the kinematic model for the wheeled mobile robot.With the help of theories of polyhedral linear differential inclusion and linear matrix inequality,both the terminal domain and the terminal controller of nonlinear model predictive control are obtained to ensure iteration feasibility of the algorithm and stability of the system.Stability of the closed-loop system is proved by Lyapunov stability theory.And validity of the algorithm is verified by comparing simulation results.Then,on the basis of the above algorithm,a trajectory tracking control strategy of robust model predictive control is designed under the influence of external disturbances.A nonlinear extended state observer is used to estimate the external disturbances in the wheeled mobile robot system.A nonlinear model predictive control is designed for the nominal system of the kinematic model.Then the nonlinear model predictive control combines with the nonlinear extended state observer to form a robust controller of the system.A Lyapunov function is structured to prove the effectiveness of the nonlinear extended state observer.Robustness and adaptability of the algorithm are verified by simulation results.Finally,a double closed-loop control strategy is designed for kinematic model and dynamic model of the wheeled mobile robot.In view of the external disturbances in the inner loop,the active disturbance rejection control method is used to estimate and compensate the disturbances.In the outer loop,a nonlinear model predictive control strategy with diamond-shaped input constraints is proposed owing to coupling constraints of the mechanical structure.Stability of the double closed-loop system and iteration feasibility of the algorithm are analyzed theoretically.Simulation results prove the robustness and effectiveness of the double closed-loop control strategy.