Developing Safe Software Solutions for X-By-Wire Applications 2006-01-0599
A promising technology for active safety is “X-by-Wire”, where mechanical and electromechanical components are replaced by electronic functions. One of the reasons for this is to have more than the driver input in the command chain, and also include some degree of intervention by the control system in case the driver behaviour is likely to put the car at risk.
The adoption of a small number of computing nodes is a clear trend in vehicle design. A wide range of functions that are now distributed in the form of separate modules will instead be integrated. This approach will overcome the physical constraints of electrical and mechanical components and the costs of many separate electronic modules with their own power supplies. However this new arrangement can introduce hazards if the software contains flaws, the nature of these flaws comes in two types: omission (failing to adhere to a requirement) and commission (doing something that should not be done at all, not observing timeliness or violating a sequence) .
This paper presents a comprehensive safety approach to the development process of automotive software systems focusing on X-by-Wire applications. A modification to the traditional V-model Development Process is proposed as well as the use of the Rapid Object-Oriented Development Process for Embedded Systems. The system and controls are modelled in UML and then, as part of the safety assurance, can be analysed using hazard analysis techniques such as HAZOP, FMEA or Fault Trees.
The use of UML introduces a better communication between the different stakeholders of the project, as well as increasing the possibilities for reuse, and reliability; reducing development and systems integration time and costs.
In particular this paper describes the use of HAZOP as part of a systematic approach to develop complex software for embedded systems in safety-related applications.