Architectures hiérarchisées de contrôle global du châssis tolérantes aux défauts pour le guidage et la stabilisation d'un véhicule autonome

This thesis work aims to guarantee safe guidance in presence of certain critical driving situations such as a loss of the vehicle’s lateral stability or an actuators’ failure (steering system, braking system, etc.). To achieve this, hierarchical fault-tolerant global chassis control architectures are proposed. First, lateral stabilization is handled through a control architecture to coordinate maneuverability and stability controllers. The coordination is done by a proposed supervisor based on a pseudo phase plane combining lateral stability criteria. Then, the guidance in normal/emergency situation in the presence of a steering system failure is dealt with by proposing a control architecture allowing to replace the steering action by a differential braking. The different levels composing this architecture, from the reference generation to the control allocation passing by the longitudinal-lateral guidance controller synthesis, are developed and adapted to take into account the emergency situation. Finally, the global architecture is processed in order to coordinate the control objectives, namely the vehicle stabilization and guidance. The coordination is done at the optimization-based actuator Fault-Tolerant Control Allocation (FTCA) level. The latter allows prioritizing the control objectives and minimizing the control action according to the driving situation. The FTCA formulation is generalized to take into account several types of actuator faults and vehicle configurations.This thesis work aims to guarantee safe guidance in presence of certain critical driving situations such as a loss of the vehicle’s lateral stability or an actuators’ failure (steering system, braking system, etc.). To achieve this, hierarchical fault-tolerant global chassis control architectures are proposed. First, lateral stabilization is handled through a control architecture to coordinate maneuverability and stability controllers. The coordination is done by a proposed supervisor based on a pseudo phase plane combining lateral stability criteria. Then, the guidance in normal/emergency situation in the presence of a steering system failure is dealt with by proposing a control architecture allowing to replace the steering action by a differential braking. The different levels composing this architecture, from the reference generation to the control allocation passing by the longitudinal-lateral guidance controller synthesis, are developed and adapted to take into account the emergency situation. Finally, the global architecture is processed in order to coordinate the control objectives, namely the vehicle stabilization and guidance. The coordination is done at the optimization-based actuator Fault-Tolerant Control Allocation (FTCA) level. The latter allows prioritizing the control objectives and minimizing the control action according to the driving situation. The FTCA formulation is generalized to take into account several types of actuator faults and vehicle configurations.Les travaux de cette thèse visent à garantir un guidage sûr en présence de certaines situations critiques de conduite telles qu'une perte de stabilité latérale du véhicule ou une défaillance d’actionneurs (système de direction, de freinage, etc.). Pour ce faire, des architectures hiérarchisées de contrôle global du châssis tolérantes aux défauts sont proposées. D’abord, la stabilisation latérale est traitée à travers une architecture de commande permettant de coordonner les correcteurs de manœuvrabilité et de stabilité. La coordination est faite par un superviseur proposé basé sur un pseudo plan de phase combinant des critères de stabilité latérale. Ensuite, le guidage en situation normale/urgence en présence d'une défaillance du système de direction est abordé en proposant une architecture de commande permettant de remplacer l'action du braquage par un freinage différentiel. Les différents niveaux composant cette architecture, allant de la génération des références à l’allocation de commande en passant par la synthèse du correcteur de guidage longitudinal-latéral, sont développés et adaptés afin de prendre en compte la situation d'urgence. Enfin, l'architecture globale est traitée afin de coordonner les objectifs de commande, à savoir la stabilisation et le guidage du véhicule. La coordination se fait au niveau d’une allocation de commande tolérante aux défauts actionneurs (FTCA) basée sur optimisation. Cette dernière permet prioriser les objectifs de commande et de minimiser l’action de commande selon la situation de conduite. La formulation de la FTCA est généralisée afin de tenir compte de plusieurs types de défauts actionneurs et de configurations de véhicules

Coordinated AFS and DYC for autonomous vehicle steerability and stability enhancement

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Coordinated AFS and DYC for autonomous vehicle steerability and stability enhancement

International audienceIn this paper, the hierarchical yaw stability control architecture is introduced. This approach coordinates two controllers, namely the steerability and the stability controllers improving respectively the handling performance and the lateral stability. Thus, each controller has a control domain, a control objective, and its own active system. The coordination of these controllers is made by means of a supervisor that gives activation functions to prioritize each controller according to the detected situation whether it is critical or not. Using the same controllers, two supervisors are investigated. On one hand, the sideslip angle - sideslip rate phase plan, and the simplified yaw rate - sideslip angle phase plan on the other hand. Finally, simulation results are given to show the effectiveness of the proposed approach

Direct yaw control based on a phase plan decomposition for enhanced vehicle stability

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