Research On Motion Control For The Micro Intelligent Vehicles With Backlash Hysteresis Nonlinearity

The motion control is the basis for the micro intelligent vehicles to achieve self-driving. There will be inevitable backlash when we use steering gear to control the micro intelligent vehicles’ orientation. The backlash hysteresis nonlinearity seriously hamper the precision requirement in the higher control precision of the micro intelligent vehicles. In addition, when the micro intelligent vehicles travel across the bend with high speed, the nonlinear effect is obvious which easily result in shaking on the micro intelligent vehicles, and even more seriously, overrunning the runway. However, the current research on the motion control of the micro intelligent vehicles rarely consider the effect of actuators’ backlash nonlinearity, or just simply process it as uncertain interference, while there is limit on control effect. Therefore, when it comes to the backlash nonlinearity of actuators and the micro intelligent vehicles control system with high control performance requirements, it is a great challenge in the micro intelligent vehicles automatic control field to design proper motion controller to suppress the impact of backlash nonlinearity, make the micro intelligent vehicles stably, accurately and quickly track the desired trajectory.The paper is relied on the basis of analyzing the backlash nonlinear mechanism the micro intelligent vehicles, to establish backlash hysteresis nonlinearity model of the micro intelligent vehicles actuators, besides, the dynamic model of the relation between the motion state and sideslip angle and yaw velocity is established according to dynamic characteristics of the micro intelligent vehicles. On this basis, we study the motion control method of sliding mode variable structure, suppress the impact of actuators’ backlash nonlinearity to motion control, future improve the control performance. Our work includes the following three aspects:① Research the model establishment method of the micro intelligent vehicles actuators’ backlash nonlinearity and the determination of model parameters. We analyze the actual structure characteristics of actuators and the reasons of the backlash, establish the backlash hysteresis nonlinearity model of the micro intelligent vehicles’ actuators, and take experimental method to determine the model parameters.② Research the modeling method of dynamic model of the micro intelligent vehicles based on the steering gear. By using the front wheel angle of the micro intelligent vehicles as input, we establish dynamics model of the relation between the motion state and sideslip angle and yaw velocity, then obtain the transfer function of the micro intelligent vehicles.③ Research tracking control method of the micro intelligent vehicles with backlash nonlinearity on actuators. For the actuators of the micro intelligent vehicles with backlash hysteresis nonlinearity, we propose sliding mode variable structure control algorithm to suppress the impact of backlash nonlinearity. Meanwhile, by using the Lyapunov stability theory to analyze the stability and convergence of the controlled micro intelligent vehicles, we prove that the sliding mode controller which we design can guarantee the stability of the system and the tracking error to zero. Moreover,the simulation results show that the proposed sliding mode control law can better overcome the influence of backlash nonlinearity and improves the system tracking accuracy and robustness, in comparison with traditional inverse model control laws.Summarize the above research results, the intelligent vehicles movement control system based on sliding mode controller is designed and implemented. Besides, we do a lot of experiment on going fast through the sharp turn by the system. The results show that the system still track the expected the trajectory fast, stably and accurately when faced with the bad environment such as going through the sharp turn, and suppress the shake or runaway which caused by steering gear clearance, thus proving the validity of the motion control method and the reliability of system.