Research On Automatic Steering Control System Of Intelligent Electric Vehicle

The rapid development of the automobile industry leads to the increase of the ownership of cars year by year,the popularity of cars brings convenience to human life,at the same time,it also causes serious problems,such as environmental pollution,energy consumption and other serious problems.The increase of road traffic accidents causes great damage to human life and spirit.The driving environment constituted of people,car and road in which people are the dominant component,the fatigue and distraction of drivers,as well as the wrong judgment caused by the lack of driving experience,are the main reasons of traffic accidents,therefore,if the people as the main factor is removed,it will be of great significance to improve the driving safety of the driving process.Owing to the two reasons above,it will effectively avoid many problems caused by the car to develop autonomous intelligent electric vehicles,the electrification and intelligence of vehicle that ensures development of vehicles really benefit mankind are important tendency of the vehicle in the future,.Autonomous steering is an important factor to realize the intelligent vehicle,the automatic steering and control strategy of electric vehicle are studied based on self-design electric vehicles in this thesis.The structure parameters and dynamics parameters of electric vehicle were determined through experiment,and the two degrees of freedom dynamic model based on vehicle tracking deviation is established.intelligent turned of self-steering was carried out on the electric car,the sensor of external environment information and the sensor of vehicle state are used in place of the driver's vision and other sensory organs.the information extracted by the sensor is selected and made by the computer,and the executing instruction is sent to the execution mechanism,the steering wheel control system was replaced by the stepper motor and the brake master cylinder was controlled by push rod motor in the actuator,automatic steering control is realized by the control of front wheel angle,hub motor and brake.The control strategy of the lateral movement of the electric vehicle is studied based on the vehicle dynamics model,the model predictive control algorithm is used to design the lateral motion controller by analyzing the characteristics of the control process,the horizontal distance deviation,the yaw angle deviation as well as their rates of changes are used as the state variables,the front wheel angle is used as the input variable,to achieve the realization of intelligent steering control,on this basis,the computer simulation is carried out to verify the reliability of the lateral controller.In order to improve the stability of lateral control of electric vehicle,the subject designed the longitudinal motion control strategy,the PID control and fuzzy control are used to control the electric throttle and brake,and the switching rules are also designed to realize the overall longitudinal motion control.In order to verify the reliability of the whole automatic steering system,the real vehicle test on road was carried out,through the observation and recording of traffic data show that the automatic driving system design can better control the electric car at the appropriate speed tracking and steering,when the tracking deviation appeared because of the road changes,the controller can respond quickly and reduce the deviation,so that the electric vehicle can be quickly and smoothly back to the desired state.