Abstract: A brake system for a vehicle comprises a driver operable brake pedal coupled to control a brake pressure generating unit to supply hydraulic brake pressure to front and rear hydraulically actuated wheel brakes, and wherein the rear wheel brakes are also configured to be electrically actuated; a sensor arrangement for monitoring the driver's braking intent; the brake system operable in a first mode wherein the front and rear brakes are both hydraulically actuated, and a second mode wherein the front brakes are hydraulically actuated and the rear brakes are electrically actuated, the rear brakes include a caliper assembly including brake pads operable to engage a brake rotor to brake the vehicle, the caliper assembly including a hydraulic actuating mechanism and an electric actuating mechanism, a control connected to the sensor arrangement for operating the electric actuating mechanism to actuate the rear brakes as a function of the driver's braking demand.

Abstract: Electric-mechanical-brake (EMB) pad drag is determined from measurements (which can include estimations) of EMB voltage, EMB actuator temperature, and either EMB current or EMB motor speed during an open-loop apply of the EMB pad and during an open-loop release of the EMB pad. An open-loop EMB actuator efficiency is calculated when certain conditions of the same measurements apply, whereupon the EMB actuator efficiency is calculated using at least the apply or release EMB current and a corresponding apply or release preselected (such as a nominal) EMB current or is calculated using at least the apply or release EMB motor speed and a corresponding apply or release preselected (such as a nominal) EMB motor speed.