Model-based validation of diagnostic software with application in automotive systems

Software validation aims to ensure that a particular software product fulfils its intended purpose, and needs to be performed against both software requirement as well as its implementation (i.e. product). However, for diagnostic software (i.e. a diagnoser) performing online diagnosis against certain fault models and reports diagnosis decision, the underlying fault models are usually not explicitly specified, neither by formal language nor by descriptive language. The lack of formal representation of fault models leaves the intended purpose of the diagnostic software vague, making its validation difficult. To address this issue, the authors propose various model-based techniques that can generate concrete examples of the diagnoser's key properties. Such examples are represented in an intuitive and possibly visualised way, facilitating the designers/users to approve or disapprove the conformance of the diagnoser to the intended purpose. The proposed techniques work for validation of both the requirement and implementation that can be modelled as finite state machine, and are illustrated through applications on vehicle on-board diagnostic requirement.