Research Of 4WD Vehicle's ASR Technology

Acceleration slip regulation (ASR) was developed based on Anti-lock Brake System (ABS). It is the extension of ABS to the driving course. So ABS and ASR are called a control system preventing slide by a joint name. ASR can control the slippages of the driving wheels by adjusting the driving moments acting on the driving wheels. Accordingly improves the handling performance, transverse stability, dynamic performance and economics.Four wheel drive vehicle has better cross-country performance than two wheel drive vehicle. So it usually passes for SUV. However, four wheel drive vehicle has many shortages. To drive a short-time four wheel drive vehicle is very troublesome. Because the front and rare driving bridges of a long-time four wheel drive vehicle are connected through a differential as well as the left and right driving wheels, certain wheel on the road with low coefficient of friction will result in else wheels' driving power descend much, so the power to drive the car become almost zero.ASR can possibly solve the four wheel drive vehicle's problem of slip. So this paper mainly analysis the ASR's effect on the four-wheel-drive vehicle from the angle of dynamic performance. This paper mainly includes several parts below.1. The control strategies were setted down by analysising the character of four wheel drive vehicle when driving. That is, the exceed slips of driving wheels are regulated by controlling the gun, and the relative slips of driving wheels are regulated by controlling the brake. The means of estimating the vehicle's velocity used on the ABS was used for reference.2. The mathematic model of a four wheel drive vehicle was established. Using bond-graph theory to establish systems' mathematic model is simple , convenience, obvious, accurate. In this paper, the bond-graph model of the system was established using bond-graph theory, then the state-space of the system was deduced.3. Made some researches of the ASR's control algorithms. Then discuss the application of fuzzy-PID control means on the ASR of four wheel drivevehicle. The gun controller and brake controller were designed.4. The simulation model was established under the circumstance of MATLAB/SIMULINK according to the established mathematic model. And three different road conditions were simulated and analysised.The results of simulation have shown that ASR can effectively regulated the driving wheels' slippages, furthermore, the dynamic performance be improved. At the sane time, it proved the control strategies were correct and the control algorithms were feasible.