Alex O'Connor Gibson

Application of disturbance observers to automotive engine idle speed control for fuel economy improvement

Gasoline engine fuel economy can be improved by minimizing the base spark retard, the spark reserve, during idle. Without additional compensation this approach can also lead to a significant degradation in idle speed control, ISC, disturbance rejection response. In this paper an analysis of ISC lead compensation, feed-forward and disturbance observer design techniques is presented, for ISC systems with minimal spark reserve levels. The integration of the disturbance observer within the ISC system is analyzed, including the impact of observer torque reconstruction techniques and unknown delays on the idle speed disturbance rejection response. Simulation results are used to show that the best combination of disturbance rejection response and delay variation robustness can be achieved by setting the observer torque input to zero. A high fidelity cylinder-by-cylinder nonlinear engine model and ISC simulation are used to validate the linear simulation results. The nonlinear simulation results confirm that setting the disturbance observer torque input to zero produces the best overall result with a 30 percent reduction in the maximum drop in engine speed when compared to an ISC with no lead or disturbance observer compensation. Further the disturbance rejection response compares favorably with responses from conventional ISC with high levels of spark reserve

Modeling positive intake value overlap air charge response in camless engines

Camless engines are capable of maximizing torque and fuel efficiency over a broad range of engine speeds by independently controlling the engine valves. The valve timing and operating mode changes that are required to achieve these benefits can potentially generate significant steady state and transient variations in the air charge and burned gas fraction. An unthrottled camless engine air charge model is developed that is capable of simulating the steady state and transient air charge behavior. Simulation results are used to demonstrate the impact of valve timing and engine speed variations on the air charge and burned gas response and to motivate the use of such models in the camless engine control development process.

Analysis and control of delay-dependent behavior of engine air-to-fuel ratio

The paper analyzes the influence of the delay on air-to-fuel ratio (A/F) regulation in internal combustion engines. Two feedback controller architectures, an integral controller for the case of a fast A/F sensor and a feedback linearization controller for the case of a slow A/F sensor, are considered. The collocation method is applied to determine the stability and guaranteed rate of convergence regions (charts) in the space of engine and controller parameters and we demonstrate that these charts can be used to automatically schedule A/F feedback controller gains as functions of engine operating conditions. Linear matrix inequality (LMI) techniques are employed for the analysis of disturbance rejection properties of the controllers

Sensitivity Equations Based Experiment Design and Adaptive Compensation of Transient Fuel Dynamics in Port-Fuel Injection Engines

In this paper we consider and address two topics relevant to calibration of parameters in transient fuel compensation algorithms. The first topic concerns the optimal selection of transient trajectories over which data are collected and identification of parameters in transient fuel model, the inverse of which constitutes a transient fuel compensation algorithm, is performed. We show that this problem can be formulated as an optimal control problem, and that this optimal control problem can berobust solved numerically. Even with the optimal transient trajectories, our results highlight a difficulty in identifying parameters in a transient fuel model if parameters in the model of exhaust gas mixing and in the model of the universal exhaust gas oxygen (UEGO) sensor are uncertain. The second topic addresses this difficulty through the use of adaptation to adjust parameters in a transient fuel compensation algorithm, until the deviation of measured fuel-to-air ratio from the commanded fuel-to-air ratio is sufficiently reduced. Our adaptation approach is shown to be robust to uncertainties in UEGO sensor and exhaust mixing dynamics. The theme common to both developments is the use of differential sensitivity equations.

ADAPTIVE FEEDBACK LINEARIZED VARIABLE DISPLACEMENT ENGINE INTAKE MANIFOLD PRESSURE CONTROL

Abstract This paper develops a parameterization of the intake manifold filling dynamics which are then used in the development of adaptive feedback linearization intake manifold pressure control strategies. Nonlinear simulation results are used to describe the pressure control and parameter estimation response of the designs. These results demonstrate that adaptive feedback linearization can be used to develop manifold pressure control designs that are capable of providing good pressure tracking response over a range of engine speeds and displacements. It is also shown that in the presence of large transients, the adaptive control response can be improved by using manifold pressure time constant values that are based upon steady state calibration values, during transients.