Abstract: The hydraulic actuators applied in the automotive active safety system, including anti-lock braking system, traction control system, electronics stability program, active suspension, 4-wheel steering system, are introduced. The hydraulic actuator used in the most advanced active safety system currently installed in the luxury cars is analyzed. The hydraulic actuator used in the electronics stability program (ESP) is required to have high speed to response the demand in 10 ms. The high responsibility, the parameters of the structure, the parameters of the vehicle system must be considered roundly. The method of modelling and simulating the hydraulic actuators for the automotive anti-lock braking system applied by the authors is introduced. This method can also be applied to other automotive active safety systems. Finally, the expectation of the actuator for the future active safety system is presented.

Key words: Electronics stability program, Hydraulic actuator of automobile, Modulating valve