A μ‐H∞ control strategy for decreasing torque fluctuation of electro‐hydraulic integrated braking system in mode switching

Abstract

AbstractDue to the difference of time‐domain response between hydraulic braking and regenerative braking, as well as changes of equivalent parameters and operating parameters during braking mode switching, it is liable to cause torque fluctuation, which affects braking safety and vehicle ride comfort. First, the uncertainties of vehicle load and frictional coefficient model are investigated. Second, the hybrid system theory is applied to provide state transfer condition for mode switching strategy. Finally, the control strategy that utilizes regenerative braking torque to compensate for difference of the required braking torque is designed, and a new μ‐H∞ control algorithm through D‐K iteration is presented to improve the robust performance. The proposed μ‐H∞ control strategy is examined under various braking situations, and the results indicate that (1) the μ‐H∞ controller have the advantage of robustness performance, the amplitude of regenerative braking is decreased by 6.14%, and the steady‐state error of hydraulic braking is decreased by 5.26% over the H∞, and (2) under the braking mode switching, the designed compensation control strategy has the performance of fast and accurate tracking of the desired torque, and the steady‐state error does not exceed 3.5%.