Research On Balancing Control And Trajectory Tracking Of Two-wheel Self-balancing Vehicle

The two-Wheeled Self-balancing vehicle is a form of Wheeled Mobile Robots.Due to its small size,portability and flexibility,it is widely used in traditional industries,military,search and rescue work,daily patrols and all aspects of our lives.Therefore,we should take the safety and stability of the two-wheeled self-balancing vehicle into consideration.The two-wheel self-balancing vehicle system is a typical type of underactuated and strongly coupled nonlinear system.According to the self-balancing vehicle model we constructed,the erect balance problem is studied based on the dynamic model.The trajectory tracking problem is studied based on the kinematic model with and without the sliding slip and the dynamic model with and without disturbance.The main content and innovations of the paper are as follows:(1)Firstly,according to its own structural characteristics and motion characteristics,the kinematics model under the condition of pure rolling without sliding and sliding side slip is constructed respectively.Then,based on Newton mechanical methods,taking the external interference into consideration,the nonlinear dynamic model considering the motor model is constructed.Decoupling the constructed system to obtain two independent subsystems;one is the balancing subsystem related to displacement and swing angle,and the other is the yaw subsystem related to the steering angle.Then the linear subsystem model obtained is linearized near the equilibrium point to obtain the linear subsystem model of the vehicle.(2)According to the obtained subsystem linear model,combined with the linear quadratic regulator(LQR)method and the sliding mode control method,the balance control problem of the vehicle is studied.Although the LQR method enables each state of the system to reach an equilibrium state within a limited time,it is susceptible to external interference.Combined with the sliding mode control method,the influence of external interference on system performance is reduced.The proposed control method and LQR method are compared and analyzed in its robustness.(3)Combining the kinematic equation and nonlinear dynamic equation,the trajectory tracking problem of the vehicle is studied.Firstly,under the condition of pure rolling without sliding,the nonlinear kinematics control law is designed based on the properties of arctan function and Lyapunov function,and combining with the dynamic model without considering external interference,the linear sliding mode control method is used to design the dynamic controller.Secondly,in the case of slipping and skidding,the slipping and skidding are compensated based on the sliding mode disturbance observer,and the kinematics control law is designed,and combined with the nonlinear dynamic model considering external disturbance,we design the dynamics controller using nonlinear terminal sliding mode methods.The velocity and angular velocity under the dynamic model are tracked to the kinematics control law,and the trajectory tracking problem for a given reference trajectory is realized under the premise of ensuring the balance of the tilt angle of the vehicle.