Stability Analysis of Metal Oxide Gas Sensors Using System Identification.

Metal Oxide semiconductor (MOS) gas sensors are thought to be the best to meet the present day technical and economical requirements. The poor selectivity of MOS sensors is improved by the consideration of temperature variation. In this paper, we have made the system identification and stability analysis of MOS gas sensors. Pulse modulation being a popular method of feature extraction of MOS sensors, optimization of parameters of pulse modulation becomes very significant. The selection of the sensor model that provides the most stable and desired sensor response is provided by the system identification technique. Hence the problem of choosing the best frequency and duty cycle of the temperature modulating signal of the MOS sensor is solved. The estimation of model parameters is done using iterative prediction-error minimization (PEM) method. Based on the sensor stability best suited transfer function was chosen for the MOS gas sensors, and then the sensors were operated at the respective best frequencies and duty cycles.