Research On Fuzzy Adaptive Lateral And Longitudinal Control Strategy For Intelligent Electric Vehicle

The intelligent vehicle is the future development direction of the automobile industry,and it is also a good method to solve the traffic safety problem.The motion control is one of the central problems of intelligent vehicles,including lateral control and longitudinal control.However,the intelligent vehicle has the highly nonlinear dynamic characteristics.The operating environment is complex and the vehicle is greatly influenced by external factors.The transverse and longitudinal control algorithm has the problems of low adaptability,complex calculation and uncertain parameters.Therefore,the important technology of intelligent vehicles--horizontal and vertical cooperative control is studied in this thesis.The main research contents are as follows:(1)For the longitudinal control,the improved incremental PID algorithm with variable integral and differential correction is adopted to make the speed reach the expectations quickly based on the dynamic analysis of the vehicle dynamics and the motor control characteristics in the typical operating conditions.The driving comfort is taken into consideration in the brake part.The coordinated braking method is mainly composed of motor control and electronic brake.(2)For the lateral control,this thesis adds the fuzzy correction factor according to the variable domain theory,and then takes the lateral error of a preview point in front of the road as the input.The method takes the actual running track,the steering angle of the steering wheel and the current of the EPS motor as the measurement.It outputs the EPS control signal by the three level fuzzy adaptive PID algorithm,which improves the stability and accuracy of steering.(3)For the coordinate control,this thesis takes the lateral control as the breakthrough point.It uses the feedforward + feedback strategy to coordinate the relationship between the longitudinal and lateral control during the vehicle movement.The strategy include the variable transmission ratio and the speed regulation.(4)In order to verify the effectiveness and practicability of the algorithm,the intelligent driving software is designed based on functional requirements to debug the control algorithm and adjust parameters based on the the Changan C206 electric vehicle.A large number of real vehicle tests are carried out on the campus road,including the speed control,the sterring control and the transverse and longitudinal cooperative control.The control effect is good which the error of longitudinal velocity is within 2km/h and the error of lateral trajectory is within 50 cm.All the parameters meet the expected requirements and the tests provide the real vehicle data for the further algorithm improvement.