Actuator-to-vehicle joint estimation of clamping force for sensorless control of the electro-mechanical brake system

The electro-mechanical brake (EMB) is a promising brake actuating system for electrified vehicle. To enhance the system function safety while saving space from redundancy sensors, this paper studied sensorless climbing force control for the EMB where a new climbing force estimator is proposed by fusing the information from vehicle dynamics and EMB states. The work was done with three contributions: 1) The priori clamping force characteristics were implemented to build the estimator with two parallel models, one of which was derived from the actuator rigid-body dynamics while the other was derived from vehicle longitudinal dynamics model; 2) a weighted-sum function is developed to fuse the estimation results from the two parallel models; 3) a proportional-integral observer utilizing wheel speed residual signals was developed to correct the initial estimates iteratively. Comparative study was conducted on a co-simulation platform and the results showed that the proposed method can reduce 72.2% root mean square error (RMSE) compared with the conventional single-model estimation methods. Robustness analysis demonstrated that the climbing force estimations accuracy across diverse braking scenarios were consistency. The study also indicated that the improvements on climbing force estimation can improve the braking control performance.