Design of sensor network based on the signed directed graph of the process for efficient fault diagnosis

An optimally located network of sensors is a prerequisite for successful application of fault diagnosis techniques. Most of the previous work in the area of fault diagnosis deals with methodologies for identifying possible faults, given sensor data. Available literature suggests that very little work has been done on methods for optimally locating the sensors for efficient fault diagnosis. Some algorithms based on the concepts of observability and resolution were discussed in our previous work (ref 1: Raghuraj et al. AiChE J. 1999, 45 (2), 310). These algorithms are based on a digraph (DG) representation of the process. In this article, the sensor location work is extended to use the signed directed graph (SDG) representation of the process. Various issues involved in utilizing the SDG of the process for the problem of sensor location are discussed. Algorithms for sensor network design based on the SDG of the process are detailed and applied to two chemical engineering case studies. It is shown that better design can be obtained by using the SDG instead of the DG.