Braking reconstruction control for fault-tolerance in electro-mechanical brake actuator failures

Electro-mechanical brake (EMB) has been recognized as prospective braking system for electric vehicles. However, the safety issues associated with actuator failures have become the main bottleneck restricting its application. Taking other healthy actuators as redundant resources and establishing controller to reconstruct the braking force after braking failures is the main technical approach for improving EMB fault-tolerance. After literature review, the braking reconstruction control in previous studies are dedicated to a specific failure mode, such as single actuator failure, and the universality of the previous braking reconstruction methods requires further verifications. To solve that, an electric bus equipped with EMB was taken as carrier to further study the optimal braking reconstruction scheme. Specifically, an overall control architecture is presented, and the braking failure modes under the multiple factors are analyzed firstly. Subsequently, the braking reconstruction rules are built to regulate the braking force on remaining and healthy actuators upon braking failure modes. Furthermore, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>∞</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> algorithm is introduced to decide the reconstructed braking force according to the vehicle motions. Finally, the co-simulation analyses and hardware-in-the-loop (HIL) tests are carried out to evaluate the effectiveness of the braking reconstruction control in EMB actuator failures. The main results indicated that the braking reconstruction is dynamically adjusted by the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>∞</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> controller according to vehicle dynamics, and the proposed braking reconstruction control achieved the expected effects in the above conditions.