EMB Position Control Using a PI Gain Scheduling Method
A brake system is a nonlinear system which applies different compressive force depending on the position of the brake pad. The EMB(electric mechanical brake) used in passenger vehicles cannot detect the compressive force without a sensor. Therefore, it has different operating times at the same distance because the brake caliper applies different force depending on the position of the brake pad. A position controller for the EMB system was developed to control the operating time robustly at the same distance. A vector control method was used to operate the motor. The result of the position controller was used as the Q axis reference for the vector control method. The PI gain of the position was defined differently to meet the same operating time of the motor on each sector. In addition, the interval value between each position was calculated using an interpolation method. A PI gain of the position controller was tuned using the MATLAB tool, and the reliability of the position controller was verified through a simulation in the MATLAB. The verified PI controller was installed in an EMB system. The operating times were measured on each sector, showing that they were nearly identical. The proposed PI scheduling method was confirmed to have robust characteristics in a nonlinear EMB system with different amounts of compressive force depending on the position of the brake pad.
Donghoon Ban, Sungho Jin, Jaeseung Hong