Identification and characterization of the hydraulic unit in an anti-lock brake system

The present paper identifies single-input single-output linear minimum-order models for the hydraulic unit of an anti-lock brake system in the increase mode and the decrease mode. The input variable and the output variable in the models for the increase mode and the decrease mode are the pressure of master cylinder and the pressure of the brake caliper respectively. In the process of model identification, excitation signals are designed by introducing a novel method to change the states of the solenoid supply valve and the solenoid discharge valve and to generate different operating modes. It is shown that the excitation signals are persistently exciting of a certain order and cover the bandwidth of the system. In this study, the structure models (the output error model, the autoregressive with exogenous input model, the autoregressive moving-average with exogenous input model and the box Jenkins model) are identified for the increase mode and the decrease mode by employing the experimental data of a test automobile and using the ordinary least-squares method and the prediction error method. After validation of the model outcome by comparison with the experimental results, the best models are presented for the increase mode and the decrease mode of the hydraulic unit in a test automobile.