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

An optimally located network of sensors is a prerequisite for successful ap plication of fault diagnosis techniques. Most of the previous work in the a rea of fault diagnosis deals with methodologies for identifying possible fa ults, given sensor data. Available literature suggests that very little wor k has been done on methods for optimally locating the sensors for efficient fault diagnosis. Some algorithms based on the concepts of observability an d resolution were discussed in our previous work (ref 1: Raghuraj et al. Ai ChE J. 1999, 45 (2), 310). These algorithms are based on a digraph (DG) rep resentation of the process. In this article, the sensor location work is ex tended to use the signed directed graph (SDG) representation of the process . Various issues involved in utilizing the SDG of the process for the probl em of sensor location are discussed. Algorithms for sensor network design b ased on the SDG of the process are detailed and applied to two chemical eng ineering case studies. It is shown that better design can be obtained by us ing the SDG instead of the DG.