Research On Trajectory Tracking Control Of Dual-motor Independent Driven Driverless Race Car

Trajectory tracking control is the key technology of driverless race car.The thesis studies the trajectory tracking control of dual-motor independent driven driverless race car.At the same time,considering the advantages of two-motor independent driven,the independent motor driven The research of auxiliary steering control technology,the results of the research provide theoretical basis and technical support for the key technology of trajectory tracking control of driverless racing cars,and have certain reference value for the research and development of trajectory tracking of driverless car.The dissertation is funded by the National Natural Science Foundation of China(51675257)and the Liaoning Provincial University Innovative Talents Project(LR2016056).The main contents include the following aspects:Firstly,the development of steer-by-wire systems for driverless race car.On the premise that the mechanical structure of the original steering system is unchanged,a set of rack and pinion steering gears with the same parameters are added,which are arranged in parallel with the original mechanical steering system,providing a new steering power input for wire control.The steering angle input of the active steering motor.In order to prevent the interference of manned and driverless on the mechanical structure,a steer-by-wire steering clutch is designed for timely connection between the steering motor and the steer-by-wire steering gear to eliminate both interference in mechanical structure.In terms of communication between the vehicle controller and the steering motor,a communication conversion module circuit board has been independently developed to achieve communication between the vehicle controller and the steering motor.Secondly,research on the trajectory tracking control algorithm of driverless race car.On the premise of known path points,the method of estimating the slope of the path points by using a quadratic curve is used to fit a cubic path curve,and a cubic piecewise parameter equation containing time t is used to generate the trajectory curve of the horizontal and vertical position as a function of time.From this,the tracking trajectory points are calculated.The spatial state equation of the vehicle's lateral tracking is established,and the state matrix in discrete time state is generated by the bilinear transformation discrete method.The linear quadratic optimal control principle is used to solve the optimal feedback control amount,combined with road curvature feedforward control,to achieve Tracking control for driverless race car with feedforward and feedback.Thirdly,the research on differential-assisted steering control of dual-motor independent driven.Combined with the principle of electronic differential steering,the steering dynamics and kinematics of dual-motor independent driven driverless race car are analyzed.Considering the influence of the electronic differential on the steering radius and lateral stability,a mathematical model of the driving motor is established.Differential torque control strategies for Ackerman geometry steering and differential drive control strategies based on yaw angular velocity are studied separately for the two strategies.Finally,experimental verification.A dual-motor independent driven driverless race car model was established in Car Sim,and the joint simulation method with MATLAB/Simulink was used to verify the simulation experiments under linear and curved conditions.The method researched in the thesis is applied to the driverless racing car competition of Chinese college students in 2018 and 2019.Experiments show that the research method can ensure that the car has a good track tracking control effect,and the differential drive also improves the stability of track tracking,and excellent results have been achieved in the Chinese college students driverless racing car competition.