An air quality sensor system with a momentum back propagation neural network

An Air Quality Sensor (AQS), located near a fresh air inlet, serves to reduce the amount of pollution entering a vehicle cabin through the HVAC (heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high-pollution area. One chip sensor module, which included a dual gas sensor, humidity sensor and temperature sensor, was developed for an AQS system in automobile. The dual gas sensor combined a reducing gas-sensing element with an oxidizing gas-sensing element on the same substrate to detect toxic oxidizing gases and reducing gases simultaneously. With this sensor module, a PIC (Peripheral Interface Controller) microcontroller was designed with a back propagation neural network to reduce the detection error when the motor vehicles pass through an area with a complicated mixture of gases. The signal from the neural network was modified to give a control signal for the inlet of automobile and to display the outdoor gas environment on the driver's panel or to alert the driver of the dangerous situation.