Nowadays, safety plays a crucial role everywhere, especially in those engineering application where human life might be in danger. In other cases, occurring malfunctions simply induce system breakdowns causing serious economic loss. Therefore, we invest more and more energy to invent new solutions to secure system design. Fault Detection and Isolation (FDI) is a framework for methodologies aiming at monitoring system healthy and providing a systematic way of alarming whenever faulty behavior appears.
In most of the cases Fault Detection and Isolation (FDI) is coupled to automatic control due to historical reasons. The need for FDI has been formulated as a control theoretical goal to reach. Society and environmental needs establish more and more demands to complex, integrated solutions in control and system theory. New research trends have been in the focus of control theory (e.g. aerospace), where automatic control design is jointly considered with safety related system aspects. In these specific cases, the goal of the control system design is not only to reach a required closed-loop performance level by the feedback controller (e.g stability), but also to accommodate possible failures occurring in the system, i.e. what if part of the system fails. Faults and failures are classified as a not permitted variation of system parameters or signals from about their nominal values. Accommodation of these malfunctions is achieved by implementing additional units, by Fault Detection and Isolation (FDI) logic. This logic is a redundant component and capable to recognize the presence of faulty behavior based on measurable quantities.
The goal of this FDI project at Chalmers is to advance the state-of-the-art of FDI field with specific focus to transportation related applications. The idea followed in this project is to mimic the fault-free system behavior by mathematical models, and compare these faultless answers with those measured in the reality. Theoretical difficulty of this solutions can be originated from the complexity of the real system (and model) as well as from the uncertainty, noise terms. The most important role of FDI is to become an indicator for system health-parameter. How can we make use of the detected malfunction? Generally speaking, embedded FDI in automatic control design, theoretically results in a coupled solution where both the parameters of the controller and the diagnosis unit have to be jointly designed. This integrated and safety oriented controller synthesis concept is also in the line of research of the current project (Fault Tolerant Control Systems).
This research project is supported by the Transport Area of Advance. Since in transportation systems human beings are involved, the need to save lives or reduce damages in any incidental cases is primordial. Therefore, the detection and isolation of traffic incidents in alternative hierarchical levels (e.g. vehicle, vehicle flow) is one of nowadays biggest challenge. Safety related system design in transportation systems cannot be regarded as the single objective rather than has to be embedded into an (semi-) autonomous environment (e.g. adaptive cruise control). The consequence is that FDI techniques have to be adapted and fitted into this context. To reach green and safe future transportation systems, researchers can introduce alternative autonomous control solutions (e.g. traffic light harmonization based on current road traffic situation) combined with safety features (e.g. reduce the probability of incidents).
Apart from the FDI application in traffic systems, this project carries lots of potentials for any type of (autonomous or not) system applications where safety is an issue (e.g. aerospace, nuclear power plants). These types of model-based FDI methods can be applied to obtain a systematic way to monitor a system (e.g. to predict maintenance). Furthermore, by combining FDI method with control synthesis, system reconfiguration can be performed. Finally, detecting faults can also be generalized in the concept of detecting unknown inputs (such as environmental changes or generic exogenous signal) to wider the scope of the project.
The success of the project is based on the duality of promoting the FDI field both in theoretical and practical directions.