Filtered High Gain Observer for an Electric Vehicle's Electro-hydraulic Brake: Design and Optimization Using Multivariable Newton-Based Extremum Seeking

Designing high-gain observers (HGOs) for the state estimation of an electric vehicle's electrohydraulic brake (EHB) system is challenging. This type of observer is applicable to model nonlinearities and constant feature gains. However, they are very sensitive to measurement noise, which is unavoidable in EHB. The first novelty of this study is that it compensates for the measurement noise using a filtered high-gain observer (FHGO) to ensure EHB state estimation. The proposed FHGO provides an estimate of the master cylinder pressure, motor current, and rotor speed from measurements of the rotor position. The second novelty is the design of an extremum-seeking (ES) optimization loop to adjust the FHGO gains online. The performance of the developed FHGO with ES-based online gain optimization was highlighted in the presence of model uncertainties and output measurement noise using a Matlab/Simulink simulation. The superiority of the FHGO (even with a fixed gain) over a standard high gain observer (SHGO) was also demonstrated.