Research On Vehicle Dynamics Integrated Control And Tire Force Distribution Under Extreme Conditions

With the rapid development of the automobile industry,the driving speed of modern cars is getting higher and higher.Therefore,the lateral stability of cars under the extreme conditions of sharp turns is still an important subject for the development of modern cars.Direct Yaw Moment Control and Active Front Steering can effectively improve vehicle stability.However,the braking effect of DYC can significantly reduce the speed of vehicle,thus affecting the driving comfort.However,when AFS is working,it is not easy to be detected by the driver.However,when the tire side deflection exceeds the saturation limit,the yaw moment is not sensitive to the compensating steering Angle generated by AFS system.Therefore,this paper studies the vehicle stability control method that integrates the two systems.The main content of the study is as follows.First in this paper,based on the Lagrange mechanics analysis method to establish a eight degrees of freedom nonlinear vehicle model,in order to ensure that the established vehicle model more close to the actual dynamic characteristics of the vehicle,so you also based on a domestic level A0 car and some experimental equipment,selection of single line and double line test conditions,the vehicle model founded by real vehicle parameters calibration real vehicle test.The simulation vehicle model is provided for the realization of vehicle stability control strategy.Secondly,the centroid Angle of a vehicle is an important parameter to represent the stability of the vehicle.In this paper,an estimator based on kalman filter is designed to estimate the vehicle centroid.In order to obtain the real-time tire force,this paper also estimates the tire force based on the extended kalman filter.Then the integrated controller of hierarchical control of AFS and DYC is studied.Based on the Linear system optimal Quadratic Regulator,the upper controller used the yaw velocity and the lateral Angle of the center of mass as the state variables of LQR and derived the two controllers in detail.Then,according to the degree of tire deformation,two control methods are proposed to adapt to the working conditions.Based on the fuzzy control theory,the weight contributed by the two control methods in each working condition is calculated online.The design of the lower controller is based on the optimal allocation method,and the objective function is established based on the minimum utilization ratio of tire force.Finally,the feasibility of the proposed control strategy is simulated under various operating conditions.Finally,based on the dSPACE rapid control prototype system and a certain electric power steering pure electric vehicle,the hardware simulation test bench of the active front wheel steering control system in the ring is established.The dSPACE software and hardware usage of the hardware used in the ring test are introduced in detail,and the model of the hardware used in the ring test is also introduced.Finally,the hardware simulation experiment in the loop is carried out.