Veri cation of Embedded Systems Using Synchronous Observers

This paper is a study of observer-based proof techniques applied to the veri cation of a model of a real world embedded system, an aircraft landing gear. We present a formal description of these techniques (taken from [5]) and look at three ways of applying them, comparing veri cation of the composed system with two approaches to decompositional veri cation. The example illustrates that due to the tight interaction in a plant-controller setting there is often little to be gained by adopting a decompositional approach to veri cation. Nonetheless, two reasons are presented for separation between the controller and its environment at the modelling stage. Hence the result of the study is that in cases similar to this one, it is most expedient to prove system properties using the composed model derived from individual parts.