공압 계측을 통한 상용차량 ABS 용 압력 제어 밸브 모델링 및 On/Off 제어 전략

Abstract

This paper reports on the modeling of a pneumatic brake system and valve control strategies for commercial vehicles with an ABS (Anti-lock Brake System). A PCV (Pressure Control Valve), consisting of two solenoid valves and two diaphragm valves, is a key part of a pneumatic ABS. To examine the pneumatic ABS, a PCV model that could accurately represent the dynamics of the air flowing through the PCV components was developed. The dynamic compressible airflow equations, which can describe the flow through an orifice, were adopted to describe the directional motion of the dynamic airflow, as commanded by the driver and modified by the PCV to facilitate the ABS activity. The discharge coefficient as a function of the pressure ratio was obtained experimentally. The PCV model was verified through pneumatic measurements of the relay valve and brake chamber. The verification results demonstrated that the simulation data were in agreement with those obtained experimentally. Furthermore, the PCV model was integrated with a whole vehicle model in Trucksim to conduct ABS simulation studies. The investigated system involved both the continuous wheel dynamics and inherent discontinuous characteristics of the PCV Two on/off valve control strategies based on the pressure and switching surface were introduced to regulate the slip ratio and analyzed via simulations. In addition, the switching-surface-based control strategy was evaluated through a hardware-in-loop experimental setup. The experimental results demonstrated that the implemented control strategy is effective even under uncertainties in the pneumatic ABS.