A stereo electronic nose for a mobile inspection robot

This paper describes the design of a gas-sensitive system ("mobile nose") that is suitable for use on a mobile robot. The stereo architecture comprises of two equivalent sets of gas sensors mounted inside separated ventilated tubes (or "nostrils"). To characterise the dynamic response, the whole system is modelled as a first-order sensor. The corresponding parameters, including the response and recovery time, can be obtained by fitting this model to the values recorded during a simple experiment described in this paper. Our experiments confirmed the suitability of the applied model and permitted a quantitative comparison of different set-ups. It is shown that using suction fans lowers the recovery time of the metal oxide gas sensors by a factor of two, while a solid separation between the tubes ("septum") is necessary to maintain the sensitivity of the mobile nose to concentration gradients.