Wheel Optimized Brake Torque at the VE Mechatronic Brake 2011-01-2358

Conventional brakes commence with given brake torque distribution and abruptly change to wheel individual torque corrections when ABS-ESP intervenes. This leads to less than optimal braking, firstly around the transition from “given distribution” to individual ABS-ESP control and secondly when ABS-ESP switches from “locked” to “rotating”. Neither of these states offers the optimal deceleration.

The VE mechatronic brake (EMB, electro mechanical brake) is designed to apply wheel individual braking with wheel optimized torques that give the best braking and stability from initial input to maximum deceleration, without sudden transition to ABS-ESP.

With electric drive motors, a very rapid adjustable part of wheel individual torque can be combined with the individually controllable VE brakes. Sudden wheel locking can be unlocked instantaneously with no mechanical intervention, by reduction of the regenerative torque or even with electrical acceleration, simply by commands to the e-drive motor controller. A rotating wheel with insufficient braking torque can be brought to the grip limit by a rapid regenerative brake torque increase. The instantaneously adjustable e-drive motor (generator) torque offers a mechatronic brake time to set the new wheel torque, but retains the very fast response time of the combined braking. Using this combination, a very quick vehicle yaw control response can also be achieved.

In this paper, simulations and measurements of wheel individual friction braking combined with rapid controlled e-drive motor torque is discussed, as well as other properties of this combination e.g. determination of true friction brake torque.