An Emergency Hierarchical Guidance Control Strategy for Autonomous Vehicles
Résumé
This paper introduces a vehicle guidance control architecture capable of autonomously resolving emergency situations in presence of a steering system failure. The proposed architecture is based on a hierarchical approach composed of three levels, namely the reference generation level, the guidance control level, and the control allocation level. The reference generation first delivers a normal or an emergency trajectory reference and the according speed profile depending on the information sent by the fault detection and isolation (FDI) supervisor. The emergency trajectory allows the vehicle to reach safely the emergency stop strip. The reference trajectory and speed profile tracking is obtained by decoupling the longitudinal and lateral control at a guidance level. Respective errors are subsequently converted into steering and braking/accelerating torques commands. The lowest level of the hierarchy, namely the control allocation, is meant to allocate the control commands to the multiple available actuators according to the FDI information. For example, promoting differential braking when a steering system failure is detected, guaranteeing acceptable tracking performance both in longitudinal and lateral directions.
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