I. Kolmanovsky

EGR-VGT control schemes: experimental comparison for a high-speed diesel engine

Variable-geometry turbochargers (VGTs) are employed in high-end diesel engines. These VGTs also help in controlling the trade-offs in emissions performance. Exhaust gas recirculation (EGR) is used to dilute the combustion mixture, resulting in lower peak combustion temperatures and a lower oxygen concentration and hence lower NOx emissions. In this article, we compare some of the control methodologies previously presented and some not yet presented to evaluate their benefits experimentally. We do not include any new theory. Rather we refer to other sources for the development of the controllers evaluated. We present an objective comparison of advanced control methodologies on a complex industrial problem with widespread applications. The control methodologies discussed are essentially system based, i.e., the initial controller is developed on an engine model.

Adaptive air fuel ratio control for internal combustion engines

This paper treats the control of engine air-to-fuel ratio from the perspective of adaptive control of time-delay systems. High accuracy of engine air-to-fuel ratio control is required to meet stringent emissions regulations. Two adaptive controller designs are considered. The first design is based on feed-forward adaptation while the second design is based on both feedback and feedforward adaptation incorporating the developed adaptive posicast controller. The two adaptive designs are compared with the baseline controller using simulations and vehicle experiments.

Optimization of complex powertrain systems for fuel economy and emissions

Stringent emission regulations combined with customer demands for improved fuel economy and performance have forced the automotive industry to consider more advanced powertrain configurations than standard port-fuel injected gasoline engines. Modern state-of-the-art powertrain systems may combine several power sources (internal combustion engines, electric motors, fuel cells, etc.) and various exhaust aftertreatment devices (catalytic converters, lean NOx traps, particulate filters, etc.) in addition to conventional engine subsystems such as turbochargers and exhaust gas recirculation. The determination of the way in which these systems need to be operated to meet drivers torque demand, performance and fuel economy expectations while satisfying federal emission regulations is a complex and a multiobjective optimal control problem. This paper reviews some of the approaches to this problem in the context of two case studies.

Preserving stability/performance when facing an unknown time-delay

Abstract Embedded controllers executed in real-time are, frequently, subject to a time-varying delay induced by task prioritization or communication over prioritized communication networks. Depending on the microprocessor or network load the delay value may vary. The control design that is based on the worst case assumption with respect to the delay may be very conservative and fail to deliver the adequate performance. On the other hand, the price for not properly dealing with the delay is instability. In this paper some of these issues are discussed in more detail and a control scheme is proposed which combines an unknown input observer to estimate the delayed value of the input, an on-line estimation scheme for the delay and a controller that adjusts its gains as needed to preserve system stability. Some of the aspects of the proposed scheme are discussed and illustrated with simulations on an automotive example.

A generalized reference governor for nonlinear systems

Reference governors are auxiliary systems that accept and, when needed, modify input commands to enforce pointwise-in-time state and control constraints. This paper proposes a new approach to reference governor design for nonlinear systems with unmeasured disturbance inputs. The approach relies on safety properties provided by sublevel sets of equilibria-parametrized functions. Unlike the prior literature, however, these functions need not be Lyapunov functions and the corresponding sublevel sets need not be positively invariant. Furthermore, the equilibria-parametrized functions need not be smooth, only continuous.

An MPC design flow for automotive control and applications to idle speed regulation

This paper describes the steps of a model predictive control (MPC) design procedure developed for a broad class of control problems in automotive engineering. The design flow starts by deriving a linearized discrete-time prediction model from an existing simulation model, augmenting it with integral action or output disturbance models to ensure offset-free steady-state properties, and tuning the resulting MPC controller in simulation. Explicit MPC tools are employed to synthesize the controller to quickly assess controller complexity, local stability of the closed-loop dynamics, and for rapid prototype testing. Then, the controller is fine-tuned by refining the linear prediction model through identification from experimental data, and by adjusting from observed experimental performance the values of weights and noise covariances for filter design. The idle speed control (ISC) problem is used in this paper to exemplify the design flow and our vehicle implementation results are reported.

Set-point control of nonlinear systems with state and control constraints: a Lyapunov-function, reference-governor approach

Proposes an approach to reference governor design. As in the prior literature, the governor accepts input commands and modifies their evolution so that specified pointwise-in-time constraints on state and control variables are satisfied. The new approach has several important advantages: it applies to continuous-time nonlinear systems, the design process is based on families of Lyapunov functions, the governor has a relatively simple implementation, the underlying theory is simple and self-contained. Key issues related to reference governor implementation are discussed in a general way, including the description of hybrid reference governors that allow the set of command inputs to be nonconvex.

Adaptive Idle Speed Control for Internal Combustion Engines

The paper presents an application of a recently developed adaptive posicast controller for time-delay systems to the idle speed control (ISC) problem in internal combustion (IC) engines. The objective is to regulate the engine speed at a prescribed set-point in the presence of accessory load torque disturbances such as air conditioning and power steering. The adaptive controller, integrated with the existing proportional spark controller, is used to drive the electronic throttle as an actuator. We present both simulation and experimental results which demonstrate the potential of the adaptive controller to improve the performance. In addition, the reduction in calibration time and effort which can be achieved with our approach is discussed.

Simple unknown input estimation techniques for automotive applications

A frequent situation in automotive control applications is when an unknown input needs to be estimated on-line from available state measurements. The objective of this paper is to discuss several simple techniques for on-line unmeasured input estimation from a first order system, and illustrate experimental application of one of these techniques to engine management systems.

Charge control for direct injection spark ignition engines with EGR

Modern automotive engines rely increasingly on high performance estimation and control algorithms to deliver the expected performance benefits. This paper discusses a number of control problems and issues that arise in the design of a charge controller for a lean-burn direct injection spark ignition engine with exhaust gas recirculation (EGR). To deal with uncertainties and parameter variations that can significantly affect the engine performance, the use of feedback and adaptive controllers is shown to be essential.