Design of sensor location based on various fault diagnostic observability and reliability criteria

The success of any fault diagnosis technique depends critically on the sens ors measuring the important process variables. To select the optimum number of sensors for a given process, qualitative (cause-effect), graph theoreti c approaches, based on process digraph (DG) were proposed. Graph approaches that used the concepts of observability (detecting all faults) and resolut ion (identifying the exact fault) were discussed. In this article, besides briefly summarizing these approaches, a reliability formulation for selecti ng optimal sensors is presented. The formulation takes into account quantit ative information such as fault occurrence probabilities, sensor failure pr obabilities, and sensor costs. The formulation can also handle various cons traints. Heuristics to solve the posed problem are also discussed. Sensor l ocation based on the proposed formulation is applied to a chemical process to illustrate the utility of the proposed approach. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.