To Örebro University

Robots with gas sensing capabilities can address tasks like monitoring of polluted areas, detection of gas leaks, exploration of hazardous zones or search for explosives. Most of the currently available gas sensing technologies suffer from a number of shortcomings like lack of selectivity (the sensor responds to more than one chemical compound), slow response, drift in the response, and cross-sensitivity to physical variables like temperature and humidity. The main topic of this dissertation is the discrimination of gases, therefore the scarce selectivity and slow response are the limitations of direct concern. One of the possible solutions to overcome the poor selectivity of a single sensor is to use an array of gas sensors and to interpret the response of the whole array using signal processing techniques and pattern recognition algorithms. This is an established technology as long as the sensors are placed in a measuring chamber. However, discrimination of gases with a mobile robot presents additional challenges because the sensors are directly exposed to the highly dynamic environment to be analyzed. Given the slow dynamics of the sensors, the steady-state of the response is never achieved and therefore the discrimination has to be performed on the transient phase. The contributions presented in the summarized thesis focus around the design of algorithms for gas identification in the transient phase, thus they are particularly suited to mobile robotics applications.