Influence of the control strategy choice on the safety level of a distributed control system
Résumé
This paper deals with the evaluation of dependability of distributed control systems, composed of intelligent (or with digital calculation capabilities) sensors and actuators, distributed around a fieldbus network. Intelligent devices are equipped with calculation processes and communication interfaces and they have the possibility to give a real-time image of their close environment, and also to qualify their functionality or their functioning state. The modelling tool used is Coloured Petri Nets which give the possibility to model a system which includes continuous-time variables and discrete events. The study of the system dynamic behaviour is considered as a criterion for the dependability evaluation. The work presented here is a comparison of several control algorithms and their influence on the actuator wear-out and thus on the system dependability.