Research And Estimation On The State Of Oad Adhesion Based On Braking Characteristics Of The Vehicle

Along with the rapid growth of the auto production and per capita auto ownership,driving safety has aroused extensive concerns,which has made the vehicle active safety control technology be a research focus thus.For most of vehicle active safety systems,such as Automotive anti-lock braking system(ABS),traction control system(TCS),the electric power steering system(EPS),electronic stability control system(ESP)etc.,it is quite necessary to obtain the current state parameters of the driving vehicle to realize their functions,among these parameters,the tire-road adhesion coefficient and state is especially important.So far,the basic access method of the tire-road adhesion coefficient is using various physical sensors.But its real timing,accuracy and sensors price limits it widely used in the automobile.And state estimation method is another approach which bases on vehicle dynamic characteristics,like driving characteristic,braking characteristic or Steering characteristic,etc.In this paper,the tire-road adhesion state estimation based on braking characteristic is carried out,the main research content as follows:(1)3 DOFs vehicle model and the tire model are established by studying the domestic and foreign status about the tire-road adhesion coefficient estimation,and then the accuracy and precision of model have been verified.Based on the theory of Kalman filtering and nonlinear Kalman filtering as well as comparative analysis,a tire-road adhesion state estimation method of car state observer is proposed,and its algorithm is realized in the environment of Matlab.(2)A car state observer based on nonlinear Kalman filtering theory along with a state estimation model based on the co-simulation of Carsim-Simulink is established,achieving online estimation of the state parameters such as horizontal pendulum angular velocity,centroid side-slip angle and vertical speed when the vehicle is driving.And the co-simulation analysis under braking,non-brakingor differential braking conditions is completed to verify the validity of the auto stateparameters estimation method.(3)Observation noise is processed in filter based on fuzzy control theory.EKF filter and State observer is established based on parameters estimation to estimate of the tire-road adhesion coefficient and state,and Carsim platform is used to validate the accuracy and rationality of the estimation algorithm of the tire-road adhesion state under different simulation conditions and adhesion coefficient of road surface.All in all,the tire-roadadhesion state estimation method based on braking characteristic can be applied to all vehicle active safety systems controlled by braking force.This paper is based on the estimation for auto state parameters,using auto inverse dynamics model and extended Kalman filtering theory,putting forward the tire-road adhesion state estimation recognition algorithm.Finally,a multi-conditions comparative analysis is carried out based on Carsim-Siumlink co-simulation platform to verify the validity of the algorithm.