A Research On Road Identification Based On Braking Operation

The key point of automobile electric control braking system is to adjust tangential force of road surface to tire, which is influenced by road adhesion condition. The target slip rate of ABS controller need to be adjusted by road identification result when braking to make full use of current road adhesive condition and get maximum braking force. These research contents are conducted in this text to complete road identification during breaking.(1) Identification method based on average adhesion coefficient is presented, makes average adhesion coefficient of slip rate interval [0.08,0.11] as parameter value to complete road identification. This method avoids deficiencies resulted by adhesion coefficient curves intersection and effects of adhesion coefficient transient changes on identification results.(2) Identification method based on the road characteristic coefficient is presented. The method makes dynamic identification under real-time slip rate by dynamic identification interval on T(s) curve to complete road identification on real-time slip rate.The method avoids effects of adhesion coefficient curves or slope curves on identification as identification parameter and overcomes the defect resulted by the same parameter value of different roads under several slip rates.(3) Identification method based on variation ranges of peak adhesion coefficient is presented. The six typical variation ranges of road peak adhesion coefficient are obtained by Burckhardt tire-road model. This method makes peak adhesion coefficient variation range as identification interval and road adhesion coefficient as identification parameter to complete road identification.(4) The braking torque and wheel speed are regarded as input variable and item which include road adhesion coefficient is regarded as interference to establish the extended state observer based on high gain feedback which is used to estimate road adhesion coefficient.(5) The quarter vehicle ABS sliding mode control model is established to complete simulation experiment by MATLAB/Simulink.The feasibility and validity of three methods are demonstrated by the simulation experiments on single road and variation road.The method based on variation ranges of peak adhesion coefficient is further demonstrated through road test by the on-board six-component testing system.(6) The six component testing date management system is established by VB and ACCESS database which can find and extract experiment data quickly and accurately, avoiding the shortcoming of six component testing system on data management.(7) Roads are classified based on peak adhesion coefficient and road adhesion coefficient as identification parameter to complete road identification. Allocation of braking force is made secondary according to identification result during breaking.The research results show that three road identification method based on can braking operation can complete road identification quickly and precisely, the extended state observer based on high gain feedback can estimate road adhesion coefficient quickly and precisely, front and back braking force distribution based on road identification can improve the utilization of road adhesion condition.