Air-fuel-ratio control of engine system with unknown input observer

Jing Na, Guido Herrmann, Clement Rames, Richard Burke, Chris Brace

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

8 Citations (Scopus)
397 Downloads (Pure)


This paper presents an alternative control to maintain the air-fuel-ratio (AFR) of port-injected spark ignition (SI) engines at certain value, i.e. stoichiometric value, to improve the fuel economy. We first reformulate the AFR regulation problem as a tracking control for the injected fuel mass flow rate, which can simplify the control synthesis when the fuel film dynamics are taken into account. The unknown engine parameters and dynamics can be lumped as an unknown signal, and then compensated by incorporating the unknown input observer into the control design. Only the measurable air mass flow rate through throttle, manifold pressure and temperature, and the universal exhaust gas oxygen (UEGO) sensor are utilized. Simulations based on a mean-value engine model (MVEM) illustrate that the proposed control can achieve satisfactory transient and steady-state performance with strong robustness when the engine is operated in varying speed conditions.
Original languageEnglish
Title of host publication2016 UKACC 11th International Conference on Control (CONTROL)
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages6
ISBN (Electronic)978-1-4673-9891-6
ISBN (Print)978-1-4673-9892-3
Publication statusPublished - 10 Nov 2016
Event2016 UKACC 11th International Conference on Control (CONTROL) - Queen's University, Belfast, Ireland
Duration: 31 Aug 20162 Sept 2016


Conference2016 UKACC 11th International Conference on Control (CONTROL)


  • Air-to-fuel ratio control
  • Spark ignition engine
  • Unknown input observer
  • Mean-value engine model


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