In this thesis, two problems are studied. The first problem is to find a technique to generate a particular type of failure information in real time for large flexible space structures (LFSSs). This problem is solved by using structured residuals. The failure information is then incorporated into an existing fault tolerant control scheme. The second problem is a ``spin-off'' from the first. Although the H-infinity sliding mode observer (SMO) cannot be applied to the colocated LFSS , its ability to do robust state and fault estimation of the SMO makes it suitable to be used in an integrated fault tolerant control (IFTC) scheme. We propose to combine the H-infinity SMO with a linear fault accommodation controller. Our IFTC scheme is closed loop stable, suppresses the effects of faults and enjoys enhanced robustness to disturbances. The effectiveness of the IFTC is illustrated through the control of a permanent magnet synchronous motor under actuator fault.

Vu l’importance que revêt la sûreté de fonctionnement des convertisseurs statiques dans plusieurs domaines (traction électrique, génération de l’énergie électrique à partir de l’énergie éolienne, etc,... ), il est nécessaire d'examiner la continuité de service de ces systèmes même dans le cas d’un dysfonctionnement d’un des modules IGBT, d’un bras de l’onduleur ou d'une phase de machine. Ainsi, il est indispensable de concevoir de nouvelles architectures matérielles et commandes logicielles capables de fonctionner à puissance significative même en présence de défaillance touchant le système et plus particulièrement les modules IGBT de l’onduleur. Le sujet proposé s’intéresse à une nouvelle structure hybride multiniveaux tolérante aux défauts. Elle consiste à ajouter à un convertisseur triphasé 3-niveaux type NPC (Neutral Point Clamped), un quatrième bras 3-niveaux types FC (Flying Cap). Des nouvelles techniques des différentes parties de la tolérance des pannes, à savoir la détection, l’isolation, la reconfiguration matérielle et la commande en mode dégradé, sont proposées, analysées et validées sur un prototype expérimental de 15kW de puissance. / Given the importance of power converter safety operation in several fields (electric traction, renewable energy, etc ..), it is necessary to examine availability of these systems in the case of malfunction of an IGBT module, a converter leg or a phase machine. Thus, it is essential to develop new hardware architectures and software controls capable of operating at significant power after fault occurence. This thesis deals with a new multilevel fault tolerant hybrid topology. It consists on adding to a 3-phase 3-level NPC (Neutral Point Clamped) inverter, a fourth 3-level FC (Flying Cap) leg. New techniques of fault tolerance parts, namely detection, isolation, reconfiguration and system control during post fault mode, are proposed, analyzed and validated with a 15kW experimental converter prototype.

As intelligent hydraulic systems with embedded sensors become more ubiquitous, the real or perceived reliability challenge associated with sensors must be addressed to encourage their adoption. In this paper, a fault-tolerant control strategy for an intelligent independent metering valve that allows continued operation if a sensor fails is described. The twin-spool valve example utilizes position sensors to stabilize the spool positions and eliminate hysteresis, and pressure sensors to provide digital pressure compensation, electronic load sensing, and other features. An independent metering valve has redundancy provided by four sensors working together to control the flow into and out of a single actuator. Although two sensors are needed to control the flow through a spool, the controller can be reconfigured to ensure the flow is always controlled on the spool with both sensors working. To accomplish this, the concept of cross-port pressure control is introduced that uses the faulty side of the valve to maintain constant pressure on the non-faulty side. By maintaining a constant pressure, the flow in and out of the actuator are balanced. Experimental results on the boom of a backhoe demonstrate the operation of the fault tolerant control strategy.

The purpose of this master thesis is to contribute a service-based decentralized architecture for Electronic Control Unit (ECU) with fault tolerant control. As ECU systems are becoming large-scaled, centralized-architecture fault tolerant control is facing challenges in performance, complexity and engineering, for its dependencies, non-modular, non-scalable and so on. In Scania’s ECUs, the architecture is applied by a centralized diagnose system. In this thesis, an alternative solution – service-based decentralized architecture is presented. In the architecture, both diagnostic and reconfiguration are completely decentralized in modules of ECU system. Modules can be seen as a software component with self fault tolerant control abilities, which provides different quality of service to system. A purely service view of ECU system can be built as the foundation both for fault tolerant control architecture and for modeling control system. The thesis project is, firstly to implement a general decentralized diagnostic platform which can be called by modules of Scania Exhaust Emission Control system (EEC3) system. A centralized communication node is constructed for off-board diagnosis by PC-tools. Lastly, service based architecture is built in EEC3 PUMC module as service provider.

The increase of electronics in road vehicles comes along with a broad variety of possibilitiesin terms of safety, handling and comfort for the users. A rising complexityof the vehicle subsystems and components accompanies this development and has tobe managed by increased electronic control. More potential elements, such as sensors,actuators or software codes, can cause a failure independently or by mutually influencingeach other. There is a need of a structured approach to sort the faults from avehicle dynamics stability perspective.This thesis tries to solve this issue by suggesting a fault classification method and faulttolerantcontrol strategies. Focus is on typical faults of the electric driveline and thecontrol system, however mechanical and hydraulic faults are also considered. Duringthe work, a broad failure mode and effect analysis has been performed and the faultshave been modeled and grouped based on the effect on the vehicle dynamic behaviour.A method is proposed and evaluated, where faults are categorized into different levelsof controllability, i. e. levels on how easy or difficult it is to control a fault for the driver,but also for a control system.Further, fault-tolerant control strategies are suggested that can handle a fault with acritical controllability level. Two strategies are proposed and evaluated based on thecontrol allocation method and an electric vehicle with typical faults. It is shown thatthe control allocation approaches give less critical trajectory deviation compared to noactive control and a regular Electronic Stability Control algorithm.To conclude, this thesis work contributes with a methodology to analyse and developfault-tolerant solutions for electric vehicles with improved traffic safety. / <p>QC 20131010</p>

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Freeway work zones with lane closures can adversely affect mobility, safety, and sustainability. Capacity drop phenomena near work zone areas can further decrease work zone capacity and exacerbate traffic congestion. To mitigate the negative impacts caused by freeway work zones, many variable speed limits (VSL) control methods have been proposed to proactively regulate the traffic flow. However, a simple yet robust VSL controller that considers the nonlinearity induced by the associated capacity drop is still needed. Also, most existing studies of VSL control neglected the impacts of traffic sensor failures that commonly occur in transportation systems. Large deviations of traffic measurements caused by sensor faults can greatly affect the reliability of VSL controllers. To address the aforementioned challenges, this research proposes a fault-tolerant VSL controller for a freeway work zone with consideration of sensor faults. A traffic flow model was developed to understand and describe the traffic dynamics near work zone areas. Then a VSL controller based on sliding mode control was designed to generate dynamic speed limits in real time using traffic measurements. To achieve VSL control fault tolerance, analytical redundancy was exploited to develop an observer-based method and an interacting multiple model with a pseudo-model set (IMMP) based method for permanent and recurrent sensor faults respectively. The proposed system was evaluated under realistic freeway work zone conditions using the traffic simulator SUMO. This research contributes to the body of knowledge by developing fault-tolerant VSL control for freeway work zones with reliable performance under permanent and recurrent sensor faults. With reliable sensor fault diagnosis, the fault-tolerant VSL controller can consistently reduce travel time, safety risks, emissions, and fuel consumption. Therefore, with a growing number of work zones due to aging road infrastructure and increasing demand, the proposed system offers broader impacts through congestion mitigation and consistent improvements in mobility, safety, and sustainability near work zones. / Thesis / Doctor of Philosophy (PhD) / Freeway work zones can increase congestion with higher travel time, safety risk, emissions and fuel consumption. This research aims to improve traffic conditions near work zones using a variable speed limits control system. By exploiting redundant traffic information, a variable speed limit control system that is insensitive to traffic sensor failures is presented. The proposed system was evaluated under realistic freeway work zone conditions in a simulation environment. The results show that the proposed system can reliably detect sensor failures and consistently provide improvements in mobility, safety and sustainability despite the presence of traffic sensor failures.

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