Experiences with model-centred design methods and tools in safe robotics

Development of a system is complex, requiring a well-structured process to manage the range of tasks involved and their work products. There are many models and processes available for structured development, including the well-known Waterfall and Agile models. Recent standards for safety-critical system development utilise the V-model, such as the process given in the ISO 26262 standard for functional safety of road vehicles. However, the process clashes with the commonly-expressed desire for greater reuse of development artifacts in robotics. We have experimented with applying a process, the Object-Oriented Systems Engineering Method, to the design of a robotic wheelchair. This paper describes our application of the process to a safety-critical robot, as well as our use of SysML for managing design information and ZipC for code generation and verification. We discuss our experiences, both good and bad, in order to inform other robot developers of what to consider when choosing a process and tools.