The diagnostic systems of today monitor components and subsystems more or less independent of each other. Specific faults often lead to fault manifestations on several monitors simultaneously. For instance a disconnected intake system hose can result in both flow faults (higher or lower flow than expected) and pressure faults (lower or higher pressure due to leakage). Residuals from several monitors might be needed in order to improve the ability to isolate faults. The ability to find the root cause of the fault and pinpoint it to correct component also leads to lower costs due to guarantee issues since it will be easier to avoid the replacement of components that are not broken.
Functionality already exists to reduce fault propagation to subsystems downstream (by inhibition of relevant monitors). The problem with avoiding fault propagation is that the root cause needs to be detected before faults downstream are detected. Since mostly all monitors use enable conditions for monitor activation there is a considerable risk with current methods to detect secondary faults before the actual root cause. Therefore, an improved fault isolation method needs also to consider the requirement to reconfigure immediately.
This report describes the design and development of a fault isolation scheme to primarily determine the root fault in the Volvo VEP4 MP engine. Additional effort will also be discussed such that a pragmatic ranking system can be computed for all potential faults in order to produce a better diagnosis. Some proposals of methods for Self-Healing will also be made as well. The report will also present on the consideration of intermittently active residuals and analyzed the effects onto the fault isolation performance.
Most importantly, this report will showcase the development of a simulation environment that provides a platform for a realistic modelling of the engine system and also to induce the necessary faults during simulation to gauge on the performance of the fault isolation scheme, including Self-Healing to a certain degree as well as the integration of intermittently active residuals.
|Publication status||Published - May 2015|