System modelling for safety and fault analysis

The automotive electronics that are concerned with powertrain and chassis control are by necessity integrated within the mechanical/hydraulic subsystems of a vehicle and may also have associated with them sensors and actuators which embody other physical principles. The vehicle overall has to satisfy specific, but varying, legislative requirements and user safety considerations not covered by legislation demand attention in order to avoid potential litigation. There is thus a need for an overall system view of safety to be taken in design procedures, together with an analysis of failure modes which might lead to safety issues. The objective of this paper is to demonstrate that by using a graphical approach, formal methods can be introduced into the design process alongside other methods and need not be though of as esoteric and requiring specialist software knowledge