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Journal of Sensors
Volume 2016 (2016), Article ID 5908459, 9 pages
Research Article

Estimation of Individual Cylinder Air-Fuel Ratio in Gasoline Engine with Output Delay

Department of Control Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

Received 1 March 2016; Revised 23 June 2016; Accepted 14 July 2016

Academic Editor: José A. Somolinos

Copyright © 2016 Changhui Wang and Zhiyuan Liu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The estimation of the individual cylinder air-fuel ratio (AFR) with a single universal exhaust gas oxygen (UEGO) sensor installed in the exhaust pipe is an important issue for the cylinder-to-cylinder AFR balancing control, which can provide high-quality torque generation and reduce emissions in multicylinder engine. In this paper, the system dynamic for the gas in exhaust pipe including the gas mixing, gas transport, and sensor dynamics is described as an output delay system, and a new method using the output delay system observer is developed to estimate the individual cylinder AFR. With the AFR at confluence point augmented as a system state, an observer for the augmented discrete system with output delay is designed to estimate the AFR at confluence point. Using the gas mixing model, a method with the designed observer to estimate the individual cylinder AFR is presented. The validity of the proposed method is verified by the simulation results from a spark ignition gasoline engine from engine software enDYNA by Tesis.