http://www.ifac-papersonline.net/ en Copyright 06:15 PM Tuesday 07, 2012 IFAC-PapersOnline http://www.ifacpapersonline.com 06:15 PM Tuesday 07, 2012 06:15 PM Tuesday 07, 2012 ET webmaster@ifac-papersonline.net webmaster@ifac-papersonline.net http://www.ifac-papersonline.net/Detailed/40972.html 04:00 PM Wednesday 31, 1969 In this paper we present a comparison between two different vehicle lateral dynamic control approaches: a novel Model Predictive Control (MPC) and a Linear Quadratic Regulator (LQR). Both strategies are aimed at controlling yaw rate and side slip of the vehicle through differential braking and are designed on the basis of a two-degrees of freedom planar model. On the basis of the estimate of tire longitudinal forces we estimate the range of lateral forces which the tire can exert; these bounds, together with the rate limiter of the braking system, represent the hard constraints of MPC controller and the saturations of LQR controller. The results show the benefits to use MPC controller; in particular, when drives in conditions near the physical constraints borders, the MPC controller can produce a better distribution of braking forces because of information is formalized in optimization problem. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40980.html 04:00 PM Wednesday 31, 1969 The use of mean value models in replicating the key characteristics of automotive powertrains has been well established. There has been considerable success in the application of these models to controller design, with improved emissions and performance the primary benefits. However, these low order models typically must make certain assumptions about the engine - with constant temperature operation a standard approach. As economy and emissions at every point in the drive cycle become scrutinised, the cold start operation of the engine becomes more critical and the constant temperature assumption is limiting. This paper seeks to develop an engine model framework for capturing the temperature transients and gaseous concentrations throughout the engine. It is intended for use in controller design and optimisation studies that incorporate the engine warm up period. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40973.html 04:00 PM Wednesday 31, 1969 Model predictive control (MPC) has been proposed several times for automotive control, with promising results, mostly based on a linear MPC approach. However, as most automotive systems are nonlinear, nonlinear MPC (NMPC) would be an interesting option. Unfortunately, an optimal control design with a generic nonlinear model usually leads to a complex, non convex problem. Against this background, this paper proposes a control system design based on a nonlinear system identification using a quasi linear parameter varying (LPV) structure, which is then used in a NMPC design framework. This paper presents the approach and the application to a well studied system, the air path of a Diesel engine. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40984.html 04:00 PM Wednesday 31, 1969 This paper proposes a system identification method to obtain a virtual in-cylinder air-to-fuel ratio (AFR) sensor using the measured engine variables of engine speed, manifold absolute pressure and fuel pulse width. An algebraic NARX model capable of estimating AFR, including transient behaviour, is identified from experimental data using ordinary least squares. A simple structure selection method is used to establish a low order algebraic model structure based on the correlation of the candidate terms with the output. The algebraic NARX structure should be more amenable to software implementation in current PCM architectures than those of alternative NN schemes. The ion current signal from the spark plug is introduced in a subsequent identification to improve the model quality. The information rich ion current signal is sampled every one degree of crank angle for 39 degrees during combustion and this window of data is then reduced to 6 inputs using principle component analysis. The two models are then critically compared with regards to the model fit. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40979.html 04:00 PM Wednesday 31, 1969 This paper offers a two-zone, physical, NOx model with low computational cost, implemented in C on an embedded system. The model is able to compute NOx-emission formation with high time resolution during an engine cycle. To do this the model takes cylinder pressure and injected fuel amount as inputs and produces NO concentration as output. The model as such is not new, nevertheless the physical background of the model as well as the equations upon which the model is based had to be briefly described to facilitate the understanding of the subsequent work. The main part of the paper is devoted to the process of developing an algorithm implementing the described model, techniques used and issues encountered are described. The resulting algorithm was implemented in C and tested on an embedded ARM processor. For the sake of implementation, parts of the algorithm had to be pre-computed and stored in tables, allowing significant acceleration of the computations. Since the model is non-linear, exponentially spaced tables had to be developed in order to successfully tabulate the parts needed without consuming too much memory. Much of the methods presented are also applicable in a variety other applications when it is desirable to implement fast versions of complex algorithms and models. The outcome regarding computation speed and memory needed is discussed. The final result is a low-cost NOx model, which is able to compute several orders of magnitude faster than NOx models known so far, implemented in C on an embedded system. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40954.html 04:00 PM Wednesday 31, 1969 Stochastic methods arguably offer a more theoretically appropriate approach to knock control than conventional deterministic strategies but are typically much slower in their transient response. Recently, however, a new stochastic controller was developed which responds very rapidly to knock rates above the specified target and which maintains tight regulatory control about the knock limit. The response to overly retarded conditions, however, is still relatively slow. In this paper the algorithm is refined in order to speed up the rate of recovery from retarded conditions while maintaining tight control and fast retard action. The performance of the new algorithm is compared to a conventional knock controller. The comparison demonstrates that the stochastic controller presented in this work is able to operate at a mean spark timing that is more advanced with much less cyclic variation about this mean. The transient response to excess knocking events can be as fast, or faster, than the conventional controller though this depends to some extent on the particular realization of the random knock process. The transient response to retarded conditions is still not quite as fast as the conventional controller, but is at least four times faster than that previously achieved. Overall, the results of this work suggest that the stochastic controller will deliver increased torque and engine efficiency under knock limited conditions compared to a conventional deterministic controller under the same conditions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40956.html 04:00 PM Wednesday 31, 1969 The pollutant emissions becoming more and more constraining, the automotive manufacturers need to adopt a global optimization approach of engine and exhaust after-treatment technologies. Engine control strategies seem to be an essential way to address this issue. The problem is particularly complex, considering the compromise to be reached between the drivability which must be maintained, the reduction of the fuel consumption and the in-cylinder pollutant emissions, and the optimisation of the conditions to reach high conversion efficiencies via exhaust gas after-treatment systems. The development of sophisticated control strategies and models can only be achieved with a complete understanding of the physical phenomena that occur in the combustion chamber, using experimental data and system numerical simulations. In this context, 0D predictive models of combustion and pollutant emissions, calibrated with experimental data, are particularly useful to study a wide range of parametric variations which are difficult and expensive to perform at the testbed. This paper presents an under-development combustion and pollutant emissions model, initially based on the 0D approach of Barba et al. (2000). In order to validate the model on steady state operating conditions, comparisons between experimental measurements and simulations are presented, pointing out the pollutant emissions during variations of loads and engine speeds. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40965.html 04:00 PM Wednesday 31, 1969 In the paper, the performances of a rule-based (RB) control strategy for a series Hybrid Solar Vehicle (HSV) are assessed via comparison with a batch genetic algorithm-based (GA) optimization. The RB strategy relies on heuristic rules defined by optimizing ICE start&stop strategy as function of average traction power and current solar irradiation. The comparison with the reference GA benchmark confirms the suitability of the proposed RB strategy for HSV on-board energy management. Extensive simulations were performed to test the influence of driving cycle features, power-prediction time-horizon and solar irradiation on HSV fuel economy. Such simulation analysis, beyond providing useful indications about correct implementation of the RB strategy, also demonstrates the potentialities offered by HSV powertrains in both urban and highway driving conditions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40953.html 04:00 PM Wednesday 31, 1969 This paper presents an example of combustion phasing estimation on a Diesel engine using a dedicated signal processing method applied to the engine bloc vibration signal. The proposed algorithm, based on the Bayesian inference, combines the measurement from a knock sensor with the combustion timing provided by an auto-ignition delay model. This methods does not require cylinder pressure sensor and can be implemented in real-time. The details about the methodological approach, the implementation on real time platform, and experimental results are reported in this paper. For the chosen application, we compare the estimated (knock signal) and measured (cylinder pressure signal) location of the maximum pressure gradient (LMG). The results show that this approach is relevant and the estimated LMG can be used for combustion control or diagnosis. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40958.html 04:00 PM Wednesday 31, 1969 To meet the future Euro VI pollutant standard, compression ignition engines have to be improved while maintaining the fuel consumption advantage they have versus spark ignition engines. Since technological breakthrough are not expected, the future CI engines will include more components (EGR systems, Turbocharger, DOC, Particulate filter, SCR,...) to reach as well low pollutants emissions and low fuel consumption. The single elements composing an engine might be well known today, but the optimization of the whole system represents the key point for further developments. The engine control unit must therefore include advanced control laws in order to optimize the system's response and to take advantage of the system's complexity. Thanks to the good compromise it offers between computational time and accuracy, 0D simulation offers a very interesting tool for engine system definition, calibration control development. This paper describes how a 0D engine model can improve the engine control law design for a turbocharged Diesel engine fitted with HP and LP EGR systems. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40962.html 04:00 PM Wednesday 31, 1969 By using a turbo the operating range of the HCCI engine can be increased, but at the expense of increased controller complexity. The dynamics the turbo introduces in the intake and the exhaust manifolds have a large impact on the in-cylinder mixture temperature, pressure and finally the combustion phasing. To compensate for this and to maintain desired combustion phasing, precise control of the negative valve overlap is required. A physical model is therefore developed and linearized to yield a state space model used for Kalman filter and main feedback controller design. The original nonlinear model is inverted to provide feedforward. The main actuators for the controller are the intake and exhaust cam phasing, fuel amount and timing of the injections. The main sensor signals used by the controller are the cylinder pressure, intake exhaust pressure, and intake temperature. The model is validated against experimental data, simulated with the controller and finally the controller was tested on the real engine. The article shows the big picture of how a control system for a spray guided, turbo charged, negative valve overlap HCCI engine can be developed. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40960.html 04:00 PM Wednesday 31, 1969 In order to make modern Diesel engines cleaner and more fuel efficient, their air systems architecture become more and more complex. The control strategies of these systems must take account of the multiple components interactions with minimal calibration effort required. In this context, model based techniques are very attractive. In this paper we propose a control oriented model of a variable geometry turbocharger in an architecture with two exhaust gas recirculation (EGR) loops : high pressure (HP) and low pressure (LP). This model is implemented in a basic control strategy and evaluated experimentally during tests with LP or HP EGR. The results show that the choice of EGR circuit has a high influence on the turbocharger actuator position, but that this effect is well taken into account in the model proposed. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40970.html 04:00 PM Wednesday 31, 1969 This paper addresses the improvement of load acceptance and the reduction of smoke emissions in a turbocharged marine diesel engine, during transient operation involving rapid load increases. The engine models were derived with system identification methods. Model Predictive Control provided the optimal quantity of injected air in the engine while minimizing smoke density (opacity), with constraint not to exceed a limit in intake manifold pressure, in order to avoid surge in the compressor. The effectiveness of the proposed control system was verified with transient response experiments on a full-scale marine diesel test engine. Results from various engine parameters comparing the standard operation without air injection showed improvement in transient loading. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40982.html 04:00 PM Wednesday 31, 1969 As engine designers look for ways to improve efficiency and reduce emissions, piezoelectric actuated fuel injectors for common rail diesel engines have shown to have improved response characteristics over solenoid actuated injectors and may allow for enhanced control of combustion through multi-pulse profiles or rate shaping. This paper summarizes the development of a simulation model for a piezoelectric fuel injector and associated driver that can be used for injector design and control system verification. The model injection rate, piezo stack voltage, and piezo stack current are compared to experimental injection rig data for two different rail pressures. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40952.html 04:00 PM Wednesday 31, 1969 This work investigates a method for estimating the phasing of combustion events in individual cylinders of a multi-cylinder diesel engine, based on measurements of the crankshaft torque. The investigated method consists of two parts. First, the measured torque signal is separated into its cylinder individual contributions. These contributions are then used in order to estimate cylinder individual combustion phasing using the concept of 50% torque ratio, a measure developed for torque domain combustion phasing analysis. The results show that 50% torque ratio is highly correlated with both 50% pressure ratio and 50% mass fraction burned for the compression ignited combustion in a diesel engine. The investigated method for 50% torque ratio estimation, based on crankshaft torque measurements, is able to produce estimates that have a bias of less than 0.6 CAD for all cylinders. The standard deviation of the estimation errors varies between 3 CAD to 5 CAD for different cylinders. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40971.html 04:00 PM Wednesday 31, 1969 This paper extends an LQR anti-jerk torque compensator for an automotive driveline with an optimization based handling of the backlash. The time derivative of the drive shaft torque, which is closely related to the vehicle jerk, is used as a virtual system output and regulated to zero. Thereby the controller does not need a reference model for generation of reference trajectories for the control law evaluation. The properties of the controller are discussed and the behavior is illustrated by simulation examples and verified by experiments. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40975.html 04:00 PM Wednesday 31, 1969 In this paper, an experimental validation of a constrained Nonlinear Model Predictive Control (NMPC) is shown for a Diesel engine air path. A fast parameterized approach is proposed in order for the resulting control scheme to meet the real-time requirements. The control strategy is completed by a moving horizon observer (MHO) to estimate the unmeasured states. An attractive feature of the proposed control strategy lies in its compatibility with more elaborated and fully nonlinear models since it uses the model as a black box predictor. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40976.html 04:00 PM Wednesday 31, 1969 an extensive investigation of the chemistry, the mechanism and the kinetics of the NO-NO2/NH3 SCR reactions for mobile applications was performed over a commercial Vanadium-based catalyst. On the basis of the collected results a Mars-Van Krevelen dynamic kinetic model was derived, which unifies Standard and Fast SCR into a single Redox-type approach. Intrinsic rate parameters were accordingly estimated and incorporated into a transient heterogeneous 1D+1D mathematical model of SCR monolith reactors together with the relevant geometrical and morphological characteristics of the monolith commercial catalyst The model was validated by independent dynamic runs both over powdered catalyst at the microreactor scale and over monolith catalysts in engine test bench runs at the full scale. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40983.html 04:00 PM Wednesday 31, 1969 Finding the correct top dead center (TDC) offset for an internal combustion engine is harder than it seems. This paper introduces a novel method to find the TDC offset based on a simple assumption that the heat loss power through the combustion chamber walls is constant for motored cycles in a narrow crank angle interval around TDC. The proposed method uses nonlinear least squares optimization to find the combination of specific heat ratio and TDC offset that makes the heat loss power as constant as possible. The standard deviation of the TDC estimate is approximately 0.05 degrees crank angle (CA) when using a crank resolution of 0.2 degrees CA for the measurements. The bias of the TDC estimate is in the 0-0.02 degrees CA range both when comparing to measurements with a TDC sensor and with simulated motored cycles. The method can be used both for calibration and on-board diagnostics purposes e.g. during cranking, fuel cut-off or engine switch-off. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40957.html 04:00 PM Wednesday 31, 1969 This paper gives a summary on modeling strategies for gasoline auto ignition developed within the collaborative research centre “SFB 686 – Modellbasierte Regelung der homogenisierten Niedertemperatur-Verbrennung”. The auto-ignition process is simulated with two different approaches. 3D CFD calculation of flow, injection and mixture formation, which is bi-directional coupled to a multi-zone reaction kinetics solver This 3D approach enables to analyze the thermodynamic conditions in the combustion chamber that lead to the auto ignition. Thus, the temporal and spatial occurrence of exothermic reactions and their influence on the engine process are specified in detail. To reduce the computational costs and enable multi-cycle calculations, a second simulation approach was developed to analyze the process under steady and transient operation conditions. The approach uses 1D gas exchange calculation with embedded burn function calculations based on reaction kinetics. The simulation shows good correlation to the test bench results, but requires a computational time of approximately 5 min per cycle. The calculation time can be further reduced with an approach based on a polynomial combustion model. Multi-cycle calculations are performed and compared to test bench results. Due to the small computational effort, this approach offers the possibility of a coupling to a controller design environment for synchronous simulation and control. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40967.html 04:00 PM Wednesday 31, 1969 Permanent magnet machines with both magnetic saturation and saliency effects can be directly described via Euler-Lagrangian formulation with complex currents. The Lagrangian is the sum of a mechanical kinetic energy and a magnetic Lagrangian. This second term is expressed in terms of rotor angle, complex stator and rotor magnetizing currents. Via simple modification of magnetic Lagrangian we derive a non-trivial dynamical model describing permanent-magnet machines with both saturation and saliency. We propose an experimental validation of such models on a customized torque machine of 1.2 kW. This first validation relies on injections of high frequency oscillations on the stator voltage. According to the proposed saturation model, the resulting amplitudes of the current-ripples is an increasing function of the current offset. Such dependance is effectively observed experimentally and confirmed by simulations. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40968.html 04:00 PM Wednesday 31, 1969 Abstract: Battery ageing is a key issue and experimental studies and modeling developments are critically needed to assess the underlying mechanisms that govern these complex and interrelated ageing processes. Indeed, molecular level processes then govern the long term operation of battery systems, their performance limitations and failure. This paper presents an advanced 0D-electrochemical and thermal model of a nickel-metal hydride (Ni-MH) cell recently calibrated to describe a 6,5 Ah, 168 cells, 202V nominal Ni-MH commercial battery pack and discusses its potential benefits to better understand battery performance and ageing. Comparison is made between a new pack and a three years/70 000 km old pack through high pulse power characterization test and modeling. On the basis of the electrochemical lumped parameter model under development, new energy management strategies could be proposed to ensure a precise state-of-charge (SoC) and state-of-health (SoH) on-board estimation to improve life duration of batteries. It is worth noting that the Ni-MH battery model is detailed as a case study in this paper, but this modeling approach can be applied to any Li-ion technologies. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40974.html 04:00 PM Wednesday 31, 1969 Combustion with a high amount of recirculated exhaust gas is increasingly gaining interest. Such in part load conditions a low combustion peak temperature can be achieved which yields lowest emissions but suffers from instabilities of the process and a highly non-linear behavior. These properties make a closed-loop control a requirement for transient operation but also a challenge. The paper presents an innovative non-linear Model-based Predictive Controller (NMPC) for controlling the indicated mean effective pressure (IMEP) and crank angle of 50% released heat (CA50) while accounting for constraints on the maximum pressure rise (dpmax). The implementation of the controller is presented in a framework for rapid control prototyping (RCP) that enables the user to set up a complex controller for transient operation in a short time frame. The ability of the approach is proved by application to the real engine. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40961.html 04:00 PM Wednesday 31, 1969 A non-linear multivariable control design with integral action is proposed and investigated for control of Exhaust Gas Recirculation (EGR) and Variable Geometry Turbocharger (VGT) in heavy duty diesel engines. The main control goal is to regulate oxygen/fuel ratio and intake manifold EGR-fraction, and they are specified in an outer loop. These are chosen as main performance variables since they are strongly coupled to the emissions. An existing non-linear control design based on feedback linearization is extended with integral action. In particular the control design method utilizes a control Lyapunov function, inverse optimal control, and a non-linear compensator. Comparisons between different control structures are performed in simulations showing the following four points. Firstly, integral action is necessary to handle model errors so that the controller can track the performance variables specified in the outer loop. Secondly, the proposed control design handles the non-linear effects in the diesel engine that results in less control errors compared to a control structure with PID controllers. Thirdly, it is important to use the non-linear compensator and it is sufficient to use a control structure with PID controllers and a non-linear compensator to handle the non-linear effects. Fourthly, the proposed control design is sensitive to model errors in the EGR and turbine flow model while a control structure with PID controllers and a non-linear compensator handles these model errors. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/40981.html 04:00 PM Wednesday 31, 1969 Engine optimal set-point calibration is critical for achieving the full potential of the high degree-of-freedom (HDOF) engine. At part load operating conditions, fuel economy is typically selected as a calibration objective. However, to guarantee vehicle drivability and smooth engine operation with low vibration and harshness, combustion variability must be considered as an additional objective. In this paper, simulation-based optimal engine calibration methodology is proposed and demonstrated on a SI engine with dual-independent variable valve timing (di-VVT) and a charge motion control valve (CMCV), designed specifically to improve combustion stability at low loads and speeds. The combustion variability can generally be tied to burn duration, and CMCVs accelerate burning by increasing the turbulence intensity when blocked. Accurate cost function evaluations are enabled with a multi-scale simulation approach. It utilizes high-fidelity, physics-based models to fully characterize engine responses, and subsequently captures the engine behaviour with artificial neural networks (ANN). In addition, statistical regression analysis of experimental data correlates the coefficient of variation in indicated mean effective pressure (COVIMEP) with one of the main combustion indices. Hence, trained ANNs and regression equation for the COVIMEP provide fast models suitable for evaluating the cost function during large number of optimization runs. Optimal engine set-points are determined by solving the constrained optimization problem with multiple objectives over part load operating condi http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif