Fault-tolerant control of an electrohydraulic brake using virtual pressure sensor

An approach for fault tolerant control of an electrohydraulic brake (EHB) in case of a pressure sensor failure is presented. Automotive Brake-by-Wire actuators are safety critical components, and an EHB under closed-loop pressure control is critically affected by faults in the pressure sensor. Timely fault detection and reconfiguration to use a brake pressure estimate based on motor position enhances the reliability of the system. Since the relationship between position and pressure can vary over a system's lifetime due to wear and changes in brake system characteristics, it is necessary to adapt this relationship online using operating data. This paper presents the means to perform this update using a least squares estimation routine, adapted to account for persistence of excitation and data storage limitations. Model-based fault detection functions are also presented. The proposed fault-tolerant control approach is implemented and validated on an EHB test bench with promising results.