Estimation and feedback control of air-fuel ratio for gasoline engines

Madan Kumar*, Tielong Shen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


In 4-stroke internal combustion engines, air-fuel ratio control is a challenging task due to the rapid changes of engine throttle, especially during transient operation. To improve the transient performance, managing the cycle-to-cycle transient behavior of the mass of the air, the fuel and the burnt gas is a key issue due to the imbalance of cyclic combustion process. This paper address the model-based estimation and control problem for cyclic air-fuel ratio of spark-ignition engines. A discrete-time model of air-fuel ratio is proposed, which represents the cycle-to-cycle transient behavior of in-cylinder state variables under the assumptions of cyclic measurability of the total in-cylinder charge mass, combustion efficiency and the residual gas fraction. With the model, a Kalman filter-based air-fuel ratio estimation algorithm is proposed that enable us to perform a feedback control of air-fuel ratio without using lambda sensor. Finally, experimental validation result is demonstrated to show the effectiveness of proposed estimation and control scheme that is conducted on a full-scaled gasoline engine test bench.

Original languageEnglish
Pages (from-to)151-159
Number of pages9
JournalControl Theory and Technology
Issue number2
StatePublished - 22 May 2015
Externally publishedYes


  • AFR estimation using Kalman filter
  • Discrete-time model
  • PI controller
  • combustion efficiency
  • in-cylinder charge


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