A Systematic Survey on Sensor Failure Detection and Fault-Tolerance in Ambient Assisted Living <s> Model-Based Fault Detection Systems <s> RF-based localization systems have been deeply investigated due to their flexibility and limited costs. These systems, when designed to support the independent life, are generally mission critical and they should be designed to be dependable. In this paper, we present a method to provide human localization systems with concurrent fault detection. We focus on two possible sources of faults: natural hardware (e.g., empty battery, faulty components) and human-made (e.g., device not worn). The adopted strategy relies on two independent measurement systems and on a fault detection apparatus. We present an implemented case-study, were the collected data are temporally annotated, processed, compared and, in case of anomalies, the system activates a notification, eventually to trigger an intervention. <s> BIB001 </s> A Systematic Survey on Sensor Failure Detection and Fault-Tolerance in Ambient Assisted Living <s> Model-Based Fault Detection Systems <s> Life expectancy has continuously increased in most countries over the last decades and will probably continue to increase in the future. This leads to new challenges relative to the autonomy and the independence of elderly. The development of Smart Homes is a direction to face these challenges and to enable people to live longer in a safe and comfortable environment. Making a home smart consists in placing sensors, actuators and a controller in the house in order to take into account the behavior of their inhabitants and to act on their environment to improve their safety, health and comfort. Most of these approaches are based on the real-time indoor Location Tracking of the inhabitants. In this thesis, a whole new approach for model-based Location Tracking of an a priori unknown number of inhabitants is proposed. This approach is based on Discrete Event Systems paradigms, theory and tools. The usage of Finite Automata (FA) to model the detectable motion of the inhabitants as well as different methods to create such FA models have been developed. Based on these models, algorithms to perform efficient Location Tracking are defined. Finally, several approaches aiming at evaluating the relevance of the instrumentation of a Smart Home with the objective of Location Tracking are proposed. The approach has also been fully implemented and tested. Throughout the thesis, the different contributions are illustrated on case studies. <s> BIB002 </s> A Systematic Survey on Sensor Failure Detection and Fault-Tolerance in Ambient Assisted Living <s> Model-Based Fault Detection Systems <s> Abstract In this paper, a passive method for robust fault detection and isolation is elaborated in the context of set-membership approach. The basic idea behind the proposed method is to compute a feasible set containing the states of a nonlinear system states using an interval constraints propagation method. A consistency test is performed using the q-relaxed intersection technique which consists in tolerating a given number q of outliers from m measurements. The robust feasible set, compatible with m-q observations, is then obtained and faulty sets are used for the isolation procedure. An application, within the framework of robot/human localization, is given to verify the efficiency of the method. <s> BIB003 </s> A Systematic Survey on Sensor Failure Detection and Fault-Tolerance in Ambient Assisted Living <s> Model-Based Fault Detection Systems <s> In this paper, we propose a discrete event system approach for location tracking of a single indoor inhabitant in Smart Home. We first construct the discrete event system model for the dynamics of the inhabitant and define the motions from one zone to another zone in the house as the events of the model. The model size is then linear with the number of the zone which is an advantage compared with the previous work. We adopt the state tree in Graph Theory to describe the observations of these events. Each branch from the root node to the terminal node represents an observable event or the occurrence of a disturbance. We then use the state estimation knowledge of discrete event systems to construct an observer to implement location tracking. Our results are optimal. Finally, we propose an reset procedure to deal with transient sensor faults. <s> BIB004
The reviewed model-based fault detection systems do not seem to provide better results than the correlation-based fault detection systems. The approaches mainly rely on checking if the sensor trigger is consistent with the predicted location of the resident. The method proposed in BIB001 that uses RF-based localization system in addition to the environmental binary sensors installed at home, can not identify if the fault source is the localization system or the installed sensors. In another research work BIB002 , applying residual-based fault detection to the location tracking finite automata model of an inhabitant could not detect nor isolate the faulty sensors. Only preventing the transient sensor faults from blocking the discrete event location tracking model was proposed in BIB004 ; however, it was not even capable of tolerating those faults. In BIB003 , comparing the motion sensors triggers with the random walk mobility model is not reliable, since this mobility model can produce unrealistic patterns as it does not keep track of the past locations and speed.