Identification of the operational configurations of automatic systems for the design for reliability

Abstract

The structural configuration as well as pre-programmed discrete operational states of automatic equipment determines the operation time of each component during the equipment life cycle. Since at each operational state a specific component set will be operating while others will remain deactivated, the reliability estimation is affected by the operational configuration changes. Modern machines and equipment generally have several discrete operational states defined by software running in an industrial controller turning on and off devices, such as motors, valves, and so one. The design of this type of system is carried out using technical diagrams, such as electrical, hydraulic, and/or pneumatic circuits, ladder diagram, and Grafcet, but a correlated reliability model is not obtained in a trivial way. This paper presents concepts and methods based on the channel–agency net, which allows the systematic determination of operational configurations related to each state of an automatic system. As pointed in this paper, from these configurations the reliability estimation can be directly determined. In this paper, the theoretical basis is presented through an electro-hydraulic system as an example of automatic equipment.