ABSTRACT
This chapter is concerned with the important issue of ensuring that mecha tronic systems operate safely. A system which can pose a serious danger to humans or the environment is known as a safety critical system. There is no offi cial designation as to when a system is safety critical or not, although some clients may specify that a new system is to be regarded as such when they pro cure it from a developer. This is important because the development process for safety related systems is much more rigorous, and hence expensive, than normal systems. Safety critical systems can be loosely divided into two cate gories, primary and secondary.
