Research On Path-tracking Control Strategy Of Intelligent Driving Vehicle Based On Steer-by-Wire

On the occasion of the Spring Festival in 2020,the sudden COVID-19 sweeps the world,providing a strong impetus for the development of emerging industries.In some scenarios such as fixed-point transportation and virus elimination,intelligent driving vehicles have been widely used,effectively alleviating the spread of the epidemic.Accelerating the development of intelligent driving vehicles is not only a mission to serve our country’s automobile industry,but also a timely move to respond to various crises.Intelligent driving technology has obvious advantages in the automotive field,but core technologies and key issues still need further breakthroughs.Aiming at the problem of path tracking control of intelligent driving vehicles,this paper develops a feedforward and feedback control law of path tracking algorithm,a steer-by-wire variable-angle transmission ratio control strategy,and a combination of path tracking decision-making layer and steer-by-wire research on the path tracking control of the executive layer for intelligent driving vehicles based on the steer-by-wire.The main research contents and innovations of this paper are as follows:1.Based on the intelligent driving vehicle equipped with the steer-by-wire,a twodegree-of-freedom differential equation characterizing the lateral motion characteristics of the intelligent driving vehicle is derived.Based on the lateral motion characteristics of intelligent driving vehicle,a single-point preview model is constructed,and the accuracy of the preview model is verified using the actual vehicle platform.Analyzing the dynamic characteristics of the steer-by-wire system,rely on the simulation platform to complete the construction of the system model,and a comparative simulation with the mechanical steering system under double-line shifting conditions is completed to verify the reliability of the steer-by-wire system model.2.Based on the two-degree-of-freedom dynamic model of the intelligent driving vehicle,the theoretical steady-state gain of the yaw rate to the steering wheel angle is derived.And the theoretical steady-state gain is applied to the preview model,obtained the final expecting steering wheel angle according to combine with the yaw rate feedback deviation compensation.Based on the Car Sim vehicle model,under the angular step condition,the steering characteristics of several models are analyzed.And the curve formula of the correction coefficient between the simulation gain and the theoretical gain that changes with the vehicle speed is fitted,which is applied to the design based on the theoretical steady-state gain preview model and variable-angle transmission ratio control strategy.The simulation results show that the path tracking algorithm based on the simulation steady-state gain design has the effect of further improving the path tracking accuracy of intelligent driving vehicles.3.Based on the analysis of the steering characteristics of intelligent driving vehicles with fixed-angle transmission ratio,the ideal variable-angle transmission ratio control strategy of intelligent driving vehicles is designed.Considering the steady-state gain of the yaw rate to the steering wheel angle,the angle transmission ratio control strategy of the intelligent driving vehicle based on the correction coefficient is designed.The control strategy is verified by real vehicle platform and simulation.The results show that the variable-angle transmission ratio control strategy designed based on different vehicle simulation models has a positive effect.4.Relying on the Simulink&Car Sim joint simulation environment,the path tracking effect of intelligent driving vehicles equipped with simulation preview-type feedforward and feedback law of path tracking algorithm and ideal variable-angle transmission ratio control strategy was simulated and verified under different driving conditions.The results show that the intelligent driving vehicle equipped with the simulation preview-type feedforward and feedback of path tracking algorithm and variable-angle transmission ratio have higher path tracking accuracy and driving stability than the fixed-angle transmission ratio control.