Alessandro di Gaeta

Robust Discrete-Time MRAC With Minimal Controller Synthesis of an Electronic Throttle Body

The electronic throttle body (ETB) is a fundamental actuator for regulating the air mass coming into an internal combustion engine; hence, it is used to control the engine torque in any modern drive-by-wire configuration. To cope with the nonlinear and discontinuous dynamics of this automotive device, in this paper a novel discrete-time model reference adaptive control (MRAC) method is designed and experimentally tested on an ETB installed on a 2-L engine. The control strategy extends the class of the minimal control synthesis (MCS) algorithms for discrete-time systems by adding an explicit discrete-time adaptive integral action and an adaptive robust term. An in-depth experimental investigation shows that the proposed control method is a viable solution as it is robust with respect to nonlinear torques acting on the plant, and it guarantees better performance than those provided by other MRAC strategies especially for small reference signals around the limp-home position where plant nonlinearities strongly affect the ETB dynamics.

An MRAC Approach for Tracking and Ripple Attenuation of the Common Rail Pressure for GDI Engines

Abstract Gasoline Direct Injection (GDI) spark ignition engines equipped with the Common Rail (CR) system strongly improve engine performance in terms of fuel consumption and pollutant emission reduction. As a drawback the fuel pressure in the rail has to be kept as constant as possible to the demanded pressure working set-points in order to achieve the advantages promised by this technology. In this work a Model Reference Adaptive Control (MRAC) algorithm based on the Minimal Control Synthesis (MCS) strategy is proposed to reduce the residual pressure in the rail. Numerical results based on a CR mean value model, previously proposed in the literature and experimentally validated, show that a very satisfactory attenuation of the pressure ripple as well as pressure tracking are attained in different working conditions. A quantitative comparison with a classical gain scheduling model-based control approach confirms furthermore the effectiveness of the proposed adaptive control strategy.

A control oriented model of a Common-Rail System for Gasoline Direct Injection engine

Electronics has greatly contributed to the development of internal combustion engine. This progress has resulted in reducing environmental degradation, and yet continuing to support improvements in performance. Regarding gasoline engine, a considerable step forward has been achieved by Common Rail (CR) technology able to exactly regulate the injection pressure during whole engine speed range. As a consequence, the injection of a fixed amount of fuel is more precise and it is possible to perform multiple injections for combustion cycle. In this paper, the authors present a mean value model aimed at the control of a CR system for a Gasoline Direct Injection (GDI) engine. The model is based on the descriptions of electro-valve, including the actuator circuit, and the fuel pressure in the rail. The performances of the proposed model are finally depicted through comparisons with experimental data collected by a CR system mounted on a 2.0 liters spark ignition engine, showing a good accuracy and reliability.

Design and experimental validation of a model-based injection pressure controller in a common rail system for GDI engine

Progressive reductions in vehicle emission requirements have forced the automotive industry to invest in research and development of alternative control strategies. All control features and resources are permanently active in an electronic control unit, ensuring the best performance in terms of pollutant emissions and power density, as well as driveability and diagnostics. A way to attain these goals is the adoption of Gasoline Direct Injection (GDI) engine technology. In order to assist the engine management system design, through a better performance of GDI engine and the Common Rail (CR) system, in this work an injection pressure regulation to stabilize the fuel pressure in the CR fuel line is proposed and validated via experiments. The resulting control strategy is composed by a feedback integral action and a static model-based feed-forward action whose gains are scheduled as function of fundamental plant parameters. The tuning of the closed loop performance is then supported by an analysis of the phase margin and the sensitivity function. Preliminary experimental results confirm the effectiveness of the control algorithm in regulating the mean value rail pressure independently from engine working conditions, i.e. engine speed and time of injection, with limited design effort.

Model-Based Control of the Air Fuel Ratio for Gasoline Direct Injection Engines via Advanced Co-Simulation: An Approach to Reduce the Development Cycle of Engine Control Systems

Nowadays, the precise control of the air fuel ratio (AFR) in spark ignition (SI) engines plays a crucial role in meeting the more and more restrictive standard emissions for the passenger cars and the fuel economy required by the automotive market as well. To attain this demanding goal, the development of an advanced AFR control strategy embedding highly predictive models becomes mandatory for the next generation of electronic control unit (ECU). Conversely, the adoption of more complex control strategies affects the development time of the ECU increasing the time-to-market of new engine models. In this paper to solve the AFR control problem for gasoline direct injection (GDI) and to speed up the design of the entire control system, a gain scheduling PI model-based control strategy is proposed. To this aim, AFR dynamics are modeled via a first order time delay system whose parameters vary strongly with the fresh air mass entering the cylinders. Nonlinear relations have been found to describe the behavior of model parameters in function of air mass. Closed loop performances, when this novel controller is nested in the control loop, are compared to those provided by the classical PI Ziegler–Nichols control action with respect to different cost functions. Model validation as well as the effectiveness of the control design are carried out by means of ECU-1D engine co-simulation environment for a wide range of engine working conditions. The combination in one integrated designing environment of control systems and virtual engine, simulated through high predictive commercial one dimensional code, becomes a high predictive tool for automotive control engineers and enables fast prototyping.

Adaptive Tracking Control of a Common Rail Injection System for Gasoline Engines: A Discrete-Time Integral Minimal Control Synthesis Approach

Over the last decade, gasoline direct injection engines have proven to be a promising solution to reduce both emission and fuel consumption. The achievement of superior performance strongly relies on its fuel injection system based on the common rail (CR) device. In order to tame the CR pressure dynamics without any a priori knowledge of the plant parameters, we design a novel model reference adaptive control strategy that extends the discrete-time minimal control synthesis algorithm. Indeed, an explicit discrete-time adaptive integral action is added to improve closed-loop performance. Experimental results support the analytical proof of stability, and confirm the effectiveness of the novel algorithm to solve both the regulation and the tracking control problem in a wide range of working conditions. The closed-loop performance is quantitatively evaluated via engineering indices.

A model-based gain scheduling approach for controlling the common-rail system for GDI engines

The progressive reduction in vehicle emission requirements have forced the automotive industry to invest in research for developing alternative and more efficient control strategies. All control features and resources are permanently active in an electronic control unit (ECU), ensuring the best performance with respect to emissions, fuel economy, driveability and diagnostics, independently from engine working point. In this article, a considerable step forward has been achieved by the common-rail technology which has made possible to vary the injection pressure over the entire engine speed range. As a consequence, the injection of a fixed amount of fuel is more precise and multiple injections in a combustion cycle can be made. In this article, a novel gain scheduling pressure controller for gasoline direct injection (GDI) engine is designed to stabilise the mean fuel pressure into the rail and to track demanded pressure trajectories. By exploiting a simple control-oriented model describing the mean pressure dynamics in the rail, the control structure turns to be simple enough to be effectively implemented in commercial ECUs. Experimental results in a wide range of operating points confirm the effectiveness of the proposed control method to tame efficiently the mean value pressure dynamics of the plant showing a good accuracy and robustness with respect to unavoidable parameters uncertainties, unmodelled dynamics, and hidden coupling terms.

Discrete-Time MRAC with Minimal Controller Synthesis of an Electronic Throttle Body

The electronic throttle body (ETB) is a fundamental actuator for regulating the air mass coming into an internal combustion engine; hence, it is used to control the engine torque in any modern drive-by-wire configuration. To cope with the nonlinear and discontinuous dynamics of this automotive device, in this paper a novel discrete-time model reference adaptive control (MRAC) method is designed and experimentally tested on an ETB installed on a 2-L engine. The control strategy extends the class of the minimal control synthesis (MCS) algorithms for discrete-time systems by adding an explicit discrete-time adaptive integral action and an adaptive robust term. An in-depth experimental investigation shows that the proposed control method is a viable solution as it is robust with respect to nonlinear torques acting on the plant, and it guarantees better performance than those provided by other MRAC strategies especially for small reference signals around the limp-home position where plant nonlinearities strongly affect the ETB dynamics.

Basic Concepts on GDI Systems

Gasoline Direct Engines offer many advantages as compared to PFI engines, as regard efficiency and specific power. To fully exploit this potential a particular attention must be paid to the in-cylinder formation process of air/fuel mixture. More demanding performance is required to the combustion system, since injectors must provide a fine fuel atomization in considerably short time, achieving a spray pattern able to interact with in-cylinder air motion and piston top surface. This is made possible through the Common Rail technology allowing an injection pressure one order of magnitude higher as compared with that of conventional PFI engines. Fuel economy can be obtained regulating load by mixture leaning, minimizing throttle usage at low loads where pumping losses are more significant, and requiring charge stratification for a stable ignition and combustion. Charge stratification can be pursued based mainly on the sole action of the fuel spray or on its interaction with a specially shaped surface on piston top or with the air bulk motion. Depending on the modality of stratification attainment, different combustion systems can be considered. The injector design has in turn a key role being the final element of fuel metering required to the desired spray pattern, injected fuel mass per injection event, resistance to thermal stress and deposits. Injector housing and orientation with respect to the combustion chamber has to be carefully chosen, exploiting in this regard the indications of computational fluid dynamics (CFD), provided by 3D simulations. Some fundamental scheme is provided for the whole high pressure fuel delivery plant, as employed in current vehicles equipped with GDI spark ignition engines.

Common Rail System for GDI Engines

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