Lane Center Keeping And Stability Control For Intelligent Commercial Vehicles

The development of main-routes logistics and a shortage of up to ten million truck drivers have led to a rapid increase in the demand for intelligent commercial vehicles.Commercial vehicles usually travel along fixed routes or in closed venues.In this scenario,commercial vehicles have gradually begun unmanned demonstration operations.Commercial vehicles have the characteristics of a high center of mass and large changes in structural parameters before and after loading.With the increase in operating speeds,how to accurately and stably drive smart commercial vehicles along a predetermined trajectory has become one of the key issues that must be resolved in commercial operations.This paper aims to realize the stable tracking of the centerline of the lane by commercial vehicles.By studying the dynamic characteristics of tires and vehicles,it is proposed that the tire force and the curvature at the preview point are used as constraints to solve the combination of speed and turning angle that can keep the vehicle stable.The method solves the problem of stable tracking of the lane center by commercial vehicles under various road conditions and load conditions.First,based on the linear tire model,Magic-Formula and road curvature constraints,the relationship between the front wheel angle and the tracking speed is derived,and the feasible range of vehicle speed and front wheel angle is obtained.The driving speed meets the requirement of tracking accuracy while meeting the limitation of tire force.Secondly,using the hierarchical control idea,a vehicle longitudinal system control strategy is studied.The upper controller adopts PID to solve the expected acceleration based on the speed deviation.The lower-level controller uses the inverse longitudinal dynamics model to calculate the throttle opening and brake pressure to complete the tracking of the maximum stable vehicle speed.In order to ensure the smoothness of the handover,a doublethreshold handover rule is designed.And verify the performance of the longitudinal control algorithm.Combine the dynamic model and tire model to obtain a 3DOF nonlinear vehicle system model,convert the predictive control algorithm of the linear time-varying model,and combine the constraint conditions to convert the optimal problem into a standard quadratic programming problem to realize the control of the vehicle lateral movement.Aiming at the characteristics of large changes in commercial vehicle load,the extended Kalman filter is used to estimate the vehicle quality parameters,and based on the quality,combined with actual use scenarios,the vehicle’s moment of inertia,tire stiffness,etc.are estimated.Finally,by building a MATLAB/Simulink and Truck Sim co-simulation platform,the effectiveness of the extreme stable driving speed selection is verified,and it is also shown that the control system has a good tracking effect on the reference path under various working conditions.