Design for diagnostics and prognostics: A physical-functional approach

This paper describes an end-to-end Integrated Vehicle Health Management (IVHM) development process with a strong emphasis on the COTS software tools employed for the implementation of this process. A mix of physical simulation and functional failure analysis was chosen as a route for early assessment of degradation in complex systems as capturing system failure modes and their symptoms facilitates the assessment of health management solutions for a complex asset. The method chosen for the IVHM development is closely correlated to the generic engineering cycle. The concepts employed by this method are further demonstrated on a laboratory fuel system test rig, but they can also be applied to both new and legacy hi-tech high-value systems. Another objective of the study is to identify the relations between the different types of knowledge supporting the health management development process when using together physical and functional models. The conclusion of this lead is that functional modeling and physical simulation should not be done in isolation. The functional model requires permanent feedback from a physical system simulator in order to be able to build a functional model that will accurately represent the real system. This paper will therefore also describe the steps required to correctly develop a functional model that will reflect the physical knowledge inherently known about a given system.