Heterogeneous sensor arrays: Merging cameras and gas sensors into innovative fire detection systems

An innovative way of multi-criteria fire detection is introduced. In this concept image information about the monitored area is combined with knowledge about the reactive gas concentrations inside this same area to produce a fire alarm and to enable alarm verification. Key component in this new mode of fire detection is a low-cost CCD camera which is operated in a difference image (DI) mode. In the unsupervised DI mode, the average grey scale values in consecutive difference images are evaluated and compared with the outputs of a metal oxide gas sensor array which measures the reactive gas concentrations in this same area. Fire alarms are generated upon observing concurrent changes in all sensor outputs. Once obtained, the camera can be switched to the supervised imaging mode and the validity of an alarm can be assessed by normal and/or difference imaging of the monitored area. In this paper the concept of DI-based fire detection is explained, demonstrated and possible enhancements and ramifications of this new technique are discussed.