On the reconstruction of transient automotive emissions : an application of generalized predictive control theory

Due to increasing interest in the emissions-producing characteristics of today's automobiles, emissions testing procedures have come under close scrutiny. In addition, development of procedures to measure emissions of vehicles operating in "on-road" conditions have been proposed to gain knowledge of the instantaneous mass flow rates of various legislated gaseous emissions. The problem with the measurement of instantaneous flow rates is that the response of modern emissions analyzers are too slow for reliable results. Therefore, a method for improving the response of these instruments is needed.

A method is described which utilizes generalized predictive control theory concepts in conjunction with system identification techniques to improve the distorted output of these analyzers. The method is validated using a variety of experimental apparatus, including a 1988 Chevrolet Corsica for the purpose of transient emissions reconstruction.

The results indicate that the generalized predictive control algorithm used in this investigation is valid and reveals a better understanding of the instantaneous concentrations of carbon monoxide. In addition, the nature of the formulation of the algorithm demonstrates that the method can be applied to any dynamic system for the purpose of improving response characteristics.