Development of a Sensorless Control Method for a Self-Energizing Brake System Using Noncircular Gears

Electronic wedge brake (EWB) system, first introduced by Siemens VDO, is an efficient way to control a large brake clamping force electronically using a small electric motor. It is designed to amplify the clamping force of electromechanical brakes using a self-energizing effect. However, EWB is very sensitive to variations of system parametric errors, such as the friction coefficient variance during braking. The effect of parametric errors is highly amplified through the same self-energizing mechanism. A new type of EWB mechanism called an electronic noncircular gear brake is developed to avoid the potential problem due to the contamination of moving parts under very harsh operating conditions. Considering the sensitivity to parametric variation and the cost issue of clamping force measurement, a new sensorless adaptive control algorithm is developed, which functions without clamping force measurement. The robustness of the developed algorithm is verified through simulations and experiments.