Modeling for Clamping Force And Hierarchical PI Control with ADRC for EMB System

Fitting in with the trend of electrification, Electro-Mechanical Brake (EMB) is expected to play a critical role in automobile brake control. In this paper, the mathematical modeling of EMB actuator system is presented with a nonlinear estimation model of the clamping force as a resolution to sensor implementation issues. The overall control architecture of EMB system is a hierarchical control strategy including an inner loop composed by the velocity-current proportional-integral (PI) vector-controlled dual loop, and an outer loop composed by the combination of a clamping force loop and a position loop, which is switched based on the operating brake stage, satisfying respective requirements for different braking stages. The cubic nonlinearity of force estimation degrades the performance of EMB, therefore an Active Disturbances Rejection Controller (ADRC) is utilized in clamping force regulation, which meets required dynamic demands and meanwhile is easy to realize with simple structure and low debugging cost. This paper is concluded with validation of the algorithm by simulation.