Sensor value validation based on systematic exploration of the sensor redundancy for fault diagnosis KBS

For a physical system whose operating state is monitored by various sensors, one of the crucial steps involved in fault monitoring and diagnosis process is to validate the sensor values. A sensor value can be validated by observing redundant measurement values. When numerous sensors are installed at different locations in a system and if there exist certain relationships among the measured parameters, the redundancies of the sensors can be viewed as embedded throughout the system. In this paper, a technique is proposed that can systematically explore such embedded redundancies of the sensors in a system and utilize them in quickly validating sensor values. The technique is based on causal relations and their interrelations within sensor redundancy graphs (SRG´s) as defined in this paper. Any sensor in an SRG can potentially benefit from any other sensor involved in the same SRG in validation. A validity level is defined and used to express the strength of the validity of a sensor value as supported by varying degrees of evidence. The validation results also yield valuable clues to the systems´ fault diagnosis knowledge-based systems on the occurrences of system faults and their locations