Accurate Brake Torque Estimation With Adaptive Uncertainty Compensation Using a Brake Force Distribution Characteristic

Abstract

This paper presents an adaptive individual brake torque estimation method based on the characteristic of front-to-rear brake force distribution ratio. Most previous studies on tire force estimation have assumed that brake torques can be calculated out of brake pressure and given fixed brake gains. However, brake gains are proportional to brake pad friction coefficients, which are influenced significantly by operating or weather conditions. In this paper, it is assumed that the pad friction coefficients are the only uncertainties of the wheel dynamics model since they vary significantly according to the driving conditions. Furthermore, the vehicle specific brake force distribution is used to obtain the additional information. Thus, more practical aspects can be considered when calculating the brake torque. The developed algorithm is verified through simulations and experiments using a production vehicle, and it confirms that the estimation performance is improved significantly compared with that without uncertainty compensation.