Active Brake Judder Attenuation Using an Electromechanical Brake-by-Wire System

Brake judder is an undesirable phenomenon in passenger vehicles whereby disk thickness variations lead to brake torque variations (BTVs) during light braking events with a consequence of reduced braking performance and driver satisfaction. Most solutions involve passive approaches; however, in this study, a novel active brake judder attenuation strategy utilizing the capabilities of a prototype electromechanical brake (EMB) is proposed. Two attenuation algorithms with different sensor requirements are presented, where compensating clamp force commands are generated to cancel the judder causing BTV arises during light braking. The first approach is founded on the linear parameter-varying (LPV) control structure, which is designed using the output regulation theory and scheduled using wheel angular speed and acceleration. The second approach examines the adaptive feedforward compensation, where the compensator is scheduled using wheel angular position, speed, and acceleration. Experimental investigations showed favorable results for the LPV compensator, albeit with high sampling rate requirements. On the other hand, the adaptive compensator demonstrated lower sampling rate requirements with better BTV attenuation, but required wheel position measurements. These results highlight the applicability of EMB in judder reduction and the advantage of having wheel position measurements.