Trajectory Tracking Control Of Wheeled Mobile Robot Considering Longitudinal Sliding

Wheeled mobile robot is widely concerned by scholars because it can improve production efficiency and facilitate daily life.The longitudinal sliding between the wheel and the ground has not been considered in the existing research about the track tracking control of the wheel mobile robot,which affects the trajectory tracking performance of wheeled mobile robot.For this reason,This thesis studies the trajectory tracking control of a four-wheel mobile robot,and solves the problem of wheel longitudinal sliding by designing observer to estimate the sliding parameters.The aim is to accurately track the desired trajectory when the wheels are sliding longitudinally.The main research contents are as follows:For the longitudinal sliding between the wheel and the ground,the slip parameter is introduced to indicate the degree of slip when the wheel is longitudinally sliding.The same side wheel with constant speed and four-wheel independent drive are considered respectively.Based on the relationship between wheels speed and forward speed,the mathematical modeling of kinematics is established,Lagrange method and general model are used to establish the dynamic model of wheeled mobile robot.When the wheel speeds of the two wheels on the same side of the wheeled mobile robot are equal,the disturbance observer is designed to estimate the sliding parameters when the wheel is longitudinally sliding base on the kinematics model,and the stability proof of the disturbance observer is given.Based on the dynamic model,a robust controller that can track the desired trajectory is proposed.The simulation results show that the estimation of the sliding parameters is accurate by using the disturbance observer,and the robust controller can make the wheeled mobile robot achieve good trajectory tracking performance under the influence of uncertain interference.In the case of four-wheel independent drive under longitudinal sliding,based on the kinematics model,the sliding parameters of the four wheels are estimated separately according to the principle of sliding mode variable structure control.And the saturation function is used to weaken the impact of chattering on the system.The trajectory tracking controller of a wheeled mobile robot is designed using the idea of backstepping,when considering that the controller based on dynamics cannot be directly designed,and the stability of the trajectory tracking controller is proved.The simulation results show that when longitudinal sliding occurs,the wheeled mobile robot can accurately track the desired trajectory.