This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Engine Air-Fuel Ratio Control Using an Event-Based Observer
Annotation ability available
Sector:
Language:
English
Abstract
Better fuel economy, reduced exhaust emissions and better drivability strongly depend on precise control of air-fuel ratio (AFR) during both steady and transient engine operations.
A discrete, nonlinear fuel-injected SI engine model was developed and used for the design of AFR control algorithms. The engine model includes intake manifold air dynamics, fuel wall-wetting dynamics, and cycle delays inherent in the four-stroke engine processes. The sampling period is synchronous with crank angle (“event-based”) as opposed to the conventional time synchronous sampling scheme (“time-based”). The model was validated with test data over a wide range of engine operating conditions.
The exhaust O2 sensor can only provide a delayed and lagged AFR signal to the controller. This inherent delay in the measurement will slow down the system response if conventional feedback control design is used. Modern estimation theory propagates the engine model as an embedded observer to obtain an instantaneous estimate of the AFR and allows high bandwidth closed-loop control of AFR.
Precise transient AFR control requires precise knowledge of the air mass inducted which depends on the motion of the throttle with respect to the intake event. A drive-by-wire throttle was instrumented to be synchronous with the intake event. With the sampling period corresponding to every intake stroke, cycle-to-cycle AFR control could be achieved.
A laboratory port fuel-injected single cylinder CFR engine with drive-by-wire throttle was used to demonstrate the model-based AFR control structure. Air-fuel ratio followed commanded stoichiometric value within 0.5% rms during throttle transients at various operating points.
Recommended Content
Authors
Citation
Chang, C., Fekete, N., and Powell, J., "Engine Air-Fuel Ratio Control Using an Event-Based Observer," SAE Technical Paper 930766, 1993, https://doi.org/10.4271/930766.Also In
References
- Stivender D. L. “Engine air control - basis of a vehicular systems control hierarchy,” SAE Paper No. 780346 1978
- Woods R. L. “An air-modulated fluidic fuel-injection system,” ASME J. Dyn. Sys., Meas., and Contr. 101 71 76 Mar. 1979
- Aquino C. F. “Transient A/F control characteristics of the 5 liter central fuel injection engine,” SAE Paper No. 810494 1981
- Hires S. D. Overington M. T. “Transient mixture strength excursions - an investigation of their causes and the development of a constant mixture strength fueling strategy,” SAE Paper No. 810495 1981
- Eaton A. R. Patrick R. S. 1992
- Powell B. K. “A simulation model of an internal combustion engine - dynamometer system,” Proc. 1978 Summer Computer Simulation Conf. Newport Beach, CA July 1978
- Dobner D. J. “Dynamic engine models for control development - Part I: Nonlinear and linear model formulation,” Application of Control Theory in the Automotive Industry, pp. 54-74, Int. J. Vehicle Design 1983
- Moskwa J. J. Hedrick J. K. “Automotive engine modeling for real time control application,” Proc. 1987 Amer. Contr. Conf. Minneapolis, MN 341 346 1987
- Hendricks E. Sorenson S. C. “Mean value modelling of spark ignition engines,” SAE Paper No. 900616 1990
- Chang C.-F. Air-Fuel Ratio Control in an IC Engine Using an Event-Based Observer Stanford University Stanford, CA Mar. 1993
- Chin Y.-K. Coats F. E. “Engine dynamics: time-based versus crank-angle based,” SAE Paper No. 860412 1986
- Heywood J. B. Internal Combustion Engine Fundamentals McGraw-Hill New York 1988
- Wu H. “A computer model for a centrally-located, closed-loop, automotive fuel metering system,” Advanced in Computer Technology - 1980 Seireg A. 98 104 1980
- Matsumura T. Nanyoshi Y. “New fuel metering technique for compensation wall flow in a transient condition using the model-matching method,” Int. J. Veh. Design 12 3 315 323 1991
- Wu H. Blumberg P. N. “An attenuation and transport delay model for single point closed-loop fuel metering systems,” SAE Paper No. 790172 1979
- Amann G. A. “Control of the homogeneous-charge passenger-car engine - defining the problem,” SAE Paper No. 801440 1980
- Yamada T. Hayakawa N. Kami Y. Kawai T. “Universal air-fuel ratio heated exhaust gas oxygen sensor and further applications,” SAE Paper No. 920234 1992
- Fekete N. P. “Electronic throttle control using an optimal control strategy,” internal report Stanford University 1992
- Hazell P. A. Flower J. O. “Sampled-data theory applied to the modelling and control analysis of compression ignition engines - Part I,” Int. J. Contr. 13 3 549 562 1971
- Franklin G. F. Powell J. D. Workman M. L. Digital Control of Dynamic Systems Addison-Wesley 2nd MA 1990
- Athans M. “The role of modern control theory for automotive engine control,” SAE Paper No. 780852 1978
- Powers W. F. Powell B. K. Lawson G. P. “Applications of optimal control and Kalman filtering to automotive systems,” Application of Control Theory in the Automotive Industry, pp. 39-53, Int. J. Vehicle Design 1983
- Hendricks E. Vesterholm T. Sorenson S. C. “Nonlinear, closed loop, SI engine control observers,” SAE Paper No. 920237 1992
- Safonov M. G. Athans M. “Robustness and computational aspects of nonlinear stochastic estimators and regulators,” IEEE Trans. Automat. Contr. AC-23 717 725 Aug. 1978
- Nakaniwa S. Furuya J. Tomisawa N. SAE Paper No. 910084 1991
- Ishii J. Kurihara N. Shida M. Miwa H. Sekido T. “An automatic parameter matching for engine fuel injection control,” SAE Paper No. 920239 1992
- Nishiyama R. Ohkubo S. Washino S. “An analysis of controlled factors improving transient A/F control characteristics,” SAE Paper No. 890761 1989
- Iwano H. Saitoh M. Sawamoto K. Nagaishi H. “An analysis of induction port fuel behavior,” SAE Paper No. 912348 1991
- Hubbard M. Dobson P.D. Powell J.D. “Closed loop control of spark advance using a cylinder pressure sensor,” ASME J. Dyn. Sys., Meas., and Contr. 414 420 Dec. 1976
- Patrick R. S. Air-Fuel Ratio Estimation in an Otto Cycle Engine: Two Methods and Their Performance Stanford University Stanford, CA Jun. 1989