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Model Based Control Design And Rapid Calibration For Air To Fuel Ratio Control Of Stoichiometric Engines

Rajagopalan, Sai S.V.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1221851638

Abstract Details

2008, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
The air-fuel ratio control problem has been the focus of research in academia eversince the advent of microprocessor based control of automotive systems. With rising fuel costs, increased environmental consciousness, and the need to be competitive in the global market, automotive manufacturers, who have traditionally relied on extensive experimental calibration to fine tune performance, are moving towardsmodel based calibration of control gains to minimize costs and incorporate advances in power-train technology in a systematic manner. While solutions presented in the open literature to date illustrate the application of the plethora of modern control theory to this problem, calibration effort and emissions performance have not been given adequate priority. The work presented in this document bridges a gap between academia and industry by using modern advances in control theory to design a solution that significantly minimizes the calibration effort required to meet performance requirements. Through proper design of experiments, data collected from the plant is used to design mathematical models that represent the dominant dynamics observed in the intake system, the fueling, combustion and gas transport and finally the behavior of the three way catalyst. The structure of these models are chosen by a deep understanding of the physics involved. System identification is used to simplify the model structure. To capture the highly nonlinear operating condition based behavior of the plant, a linear parameter varying approach is used to schedule the model coefficients through the use of linear splines on manifold pressure, engine speed and coolant temperature. The control architecture chosen utilizes a servomechanism incorporating coordinated open and closed loop control action to meet the desired performance goal and is universal in the sense that both switching sensor and linear sensor based systems can be easily accommodated with minimal change. A rapid action inner-loop, with the pre-catalyst oxygen sensor feedback to control the engine exhaust, is used in conjunction with an outer loop with post catalyst oxygen sensor feedback, to control the oxygen storage in the catalyst. Calibration of the control gains is achieved through closed loop optimization using genetic algorithms. Parallel computing is used for this optimization. Performance and stability criteria are simultaneously incorporated in the cost function to achieve the desired goals. Numerical linear matrix inequality based tests are used to guarantee stability of the closed loop system over the entire operating region. Although the discussion in this dissertation is restricted to calibration of the inner-loop compensator, one can easily adopt the proposed techniques for the design of the outer-loop compensator, as well as for a wide variety of feedback control systems.
Stephen Yurkovich (Advisor)
134 p.
Automotive Materials; Electrical Engineering; Mechanical Engineering
AFR control; Optimization; Catalyst Oxygen storage; Model based control; model based calibration.

Recommended Citations

Citations

  • Rajagopalan, S. S.V. (2008). Model Based Control Design And Rapid Calibration For Air To Fuel Ratio Control Of Stoichiometric Engines [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1221851638

    APA Style (7th edition)

  • Rajagopalan, Sai. Model Based Control Design And Rapid Calibration For Air To Fuel Ratio Control Of Stoichiometric Engines. 2008. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1221851638.

    MLA Style (8th edition)

  • Rajagopalan, Sai. "Model Based Control Design And Rapid Calibration For Air To Fuel Ratio Control Of Stoichiometric Engines." Doctoral dissertation, Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1221851638

    Chicago Manual of Style (17th edition)

osu1221851638
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© 2008, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.