Precise pressure adjustment of electro-hydraulic brake system based on pressure-position cascade control and compensation

A control architecture consisting of feedforward compensation, friction compensation, pressure outer loop, and position inner loop is proposed for pressure control of an electro-hydraulic brake system (EHB). The pressure and position loops are cascaded to take full advantage of the accuracy of the pressure feedback and the rapidity of the position feedback. To ensure the tracking accuracy of the master cylinder pressure and actuator position, both the inner and outer loops are designed as adaptive sliding mode controllers according to the nonlinear model. Based on the cascade architecture, an online friction compensation module is constructed using motor speed and position to improve the tracking accuracy of the inner-loop controller. The feedforward compensation module is used to improve the pressure response speed and reduce the adjustment burden of the pressure outer loop. The test results show that the control strategy can achieve accurate pressure-position tracking and has excellent fault tolerance performance.