Research Of Control Strategy Of Automobile ABS System Based Four-Wheel Mathematical Model

This paper aims at discussing the controlling of anti-skid brake system. The four-wheel mathematical models of the process of vehicle braking along the straight line and curve are set up separately. The slip-ratio self-tuning control based on model reference adaptive control and double threshold-combined control based on logical threshold control are proposed. The main contents of the paper are as follows:1, Set up the mathematical modelAccording to analyze the movement situation of vehicle braking, the four-wheel mathematical models of the process of vehicle braking along the straight line and curve are set up separately in simulink.2, Control policy of slip-ratio self-tuning based on model reference adaptive controlFirstly the improved model reference adaptive control is proposed. The simulation results show that the output of the system can well track the optimal slip-ratio. The strategy can guarantee the convergence on three different roads. The optimal wheel slip-ratio for most road surfaces is between 0.1 and 0.3. Most ABS control strategies aim at maintaining the wheel slip ratio at 0.2. However, the difference between road surfaces is big, such as dry asphalt or icy road. Therefore, the optimal slip-ratio,which is given as a constant value such as 0.2 will affect the control effects of ABS. In this paper, a strategy of slip-ratio self-tuning control is proposed which is based on adding operation-cell in traditional model reference adaptive control. According to the relation of the road surfaces and the optimal slip-ratio, achieve the goal of slip-ratio self-tuning. The simulations indicate that the control method is feasible. Simulation results show that vehicle can brake at the optimal slip-ratio on different surfaces. The safety performance required by ABS is realized.3, Control of double threshold combined based on logical threshold controlIn view of the shortcoming of the threshold value's selection is always based on many experiences and the massive experiments in logic threshold control, the double threshold combined control is proposed. This control method makes use of the slip-ratio and the wheel acceleration. Simulation results show that the control effects are good, basically the slip- ratio of each wheel can undulate to neighbor the optimal slip-ratio in all road surfaces, the stop time and distance are also ideal.