Abstract
The increased use of disc brakes on passenger cars, along with the increasing stiffening of regulations on safety and emission reduction, has led the research world to focus on the prediction of brake performance and wear under different working conditions. Therefore, a proper tool is demanded to monitor the brake operation and to increase the performance of control systems such as ABS, TC and ESP by supplying an accurate estimate of the brake torque. In addition, it could be used to support a brake controller aimed at minimizing the wear volume and reducing the emissions of fine particles. Another application that has given rise to noticeable interest among the control community is the vehicle electrification. The electric vehicles demand the design of new controllers to handle the regenerative brake and to enable the blending function with conventional brakes. The mentioned controllers require the estimation of physical quantities that are not directly measurable through the already existing on-board sensors. In accordance with these needs, a state observer based on the linear Kalman filter is presented in this paper. The proposed observer provides an estimation of the vehicle hub torque and, therefore, of the brake friction coefficient encompassing the chassis and wheels rotational dynamics and relying upon the vehicle sensors signals. Such a tool is able to achieve the abovementioned goals by improving the driving safety, during emergency braking, and enhancing the actuation during service braking.
KEYWORDS Automotive brakes; Vehicle dynamics; Friction coefficient; State observer; linear Kalman filter