Study On Vehicle Integrated Conytol Of Active Steering And Independent Drive Control

Active safety has always been a hot focus in the automotive industry.With the increasing of the electronic control system and the breakthrough of active control research,multiple sub-control systems are equipped on the same vehicle,which will cause the problem of coupling and superposition of vehicle performance.In order to make the multiple dynamic control systems independently develop their own control advantages,the integrated control system of the chassis can not only eliminate the contradiction between the dynamics,but also can optimize the vehicle driving performance,thus improving the performance indicators.As the two systems of active steering system and independent drive system are the trend of future development,the study of integrated control of these two systems is of great significance for engineering application.Based on the theory of vehicle dynamics,this paper focuses on the contradiction and conflict between vehicle active steering system and independent drive system.Under the premise of maintaining two subsystem functions,the integrated control research is carried out to improve vehicle performance.(1)Vehicle modeling;For a completely vehicle,using CarSim software to modele,and using the actual vehicle to test under the same conditions of the established model and the actual vehicle,finally the effectiveness is verified;In order to obtain the phase plane,an 8-DOF vehicle model is established,which the results show that the vehicle model is corresponding to CarSim's model.(2)Vehicle state variable parameter estimation;The lateral-acceleration-based algorithm is used to obtain the road surface adhesion coefficient,and the integral method is used to achieve the estimation of the center-of-mass lateral deviation angle.The vehicle side slip angle phase plane is acquired by nonlinear theory.The stable region is divided and the fitting equation is got ahead by fitting the friction coefficient and influencing factors of vehicle speed.(3)Vehicle integrated control structure;The upper-level controller is designed with the side slip phase plane,which includes three areas including active steering control area,hybrid control area and independent drive control area.When the phase point is in the active steering control zone,active steering system is tracked at the yaw rate.While active steering and independent driving are active in a certain ratio when in the mixing zone;Only independent drive is active when it is outside the stabilization zone.Integrated control of the lower controller,including the active steering control layer and independent drive control layer,through the phase plane of the stable region,to coordinate integrated control;For the lower controller,active steering is using sliding mode control algorithm design,the independent drive system distribute the driving forces to the individual tire through the quadratic programming.(4)Based on the open-loop control of the driver and the driver-in-the-loop control of the driving simulator;The control algorithm is designed and tested based on the platform,and the integrated control algorithm and control strategy are implemented.The results show that the designed controller can integrate the advantages of two kinds of sub-controllers,solve the contradiction problem,and maximize the advantages of using the two systems to improve the performance of the vehicle.