Design Patterns for Service-Based Fault Tolerant Mechatronic Systems

Abstract: In this Master thesis a new framework for achieving fault tolerance in mechatronic systems is studied. The framework is called service-based fault tolerant control and has the advantage of being completely decentralized and modular and therefore scales very well to large system sizes. First, a method is presented for designing the signal-flow architecture of mechatronic systems of real-life size and complexity. The result is a small set of generic building blocks in the form of design patterns, a concept that has gained widespread popularity in the field of software architecture. Best practises are then established for how each of the design patterns can be extended to support fault tolerance through diagnosis and reconfiguration according to the service-based framework. These extended design patterns can be used either to aid in the construction of new and more complex mechatronic systems or as a methodology for applying service-based fault tolerant control on large existing systems. The presented methods for designing and modelling large-scale mechatronic systems have the advantages of being applicable to a large class of mechatronic systems, being easy to apply without expert knowledge, as well as having the potential for being automated in the future. Finally, a case-study demonstrates how the new methods can be used to construct a fault tolerance architecture for a real-life automotive system currently used by Scania CV AB. As a part of this study a mathematical model for the system was also constructed and implemented. The model can be used for analysis during the development phase as well as troubleshooting in a repair workshop.