Accurate Pressure Control Strategy of Electronic Stability Program Based on the Building Characteristics of High-speed Switching Valve 2019-01-1107
The Electronic Stability Program (ESP), as a key actuator of traditional automobile braking system, plays an important role in the development of intelligent vehicles by accurately controlling the pressure of wheels. However, the ESP is a highly nonlinear controlled object due to the changing of the working temperature, humidity, and hydraulic load.
When modulating the single wheel’s pressure, the opening and closing of the ESP’s internal solenoid valve working with pump causes the pressure building to be controlled near the target pressure. Among them, the high-speed switching valves, mainly including the inlet valve and the outlet valve, have the most obvious influence on the pressure regulation.
High-precision control algorithm for ESP often relies on complex institutional parameters, which is not conducive to previous research on ESP. In this paper, an accurate pressure control strategy of single wheel during active braking of ESP is proposed. First, the structure and working principle of ESP have been introduced. Then, we discuss the possibility of pulse width modulation (PWM) control based on the mathematical model of the high-speed switching valve. Subsequently, the pressure building characteristics of the inlet and outlet valves are analyzed by the hardware in the Loop (HiL) experimental platform. After that, the single closed loop pressure control strategy for the inlet valve and the cascade control strategy for the outlet valve are designed. Finally, the parameters of the control strategy are set and verified through the HiL test bench. The experimental results show that the designed control strategy could ensure that the actual pressure is accurately stabilized near the target pressure under different working conditions.