Experimental validation of a virtual engine-out NOx sensor for Diesel emission control

Motivated by automotive emissions legislations, a Virtual NOx sensor is developed. This virtual sensor consists of a real-time, phenomenological model that computes engine-out NOx by using the measured in-cylinder pressure signal from a single cylinder as its main input. The implementation is made on a FPGA-CPU architecture to ensure the NOx computation to be ready at the end of the combustion cycle. The Virtual NOx sensor is tested and validated on a Euro-VI Heavy Duty Diesel engine platform. The Virtual NOx sensor is proven to meet the accuracy of a production NOx sensor for steady state conditions. Finally, the Virtual NOx sensor has a better frequency response than the production NOx sensor.