Optimal Predictive Eco-Driving Cycles for Conventional, Electric, and Hybrid Electric Cars

International audienceIn this paper, the computation of eco-driving cycles for electric, conventional and hybrid vehicles using receding horizon and optimal control is studied. The problem is formulated as consecutive-optimization problems aiming at minimizing the vehicle energy consumption under traffic and speed constraints. The impact of the look-ahead distance and the optimization frequency on the optimal speed computation is studied to find a trade-off between the optimality and the computation time of the algorithm. For the three architectures considered, simulation results show that in urban driving conditions, a look-ahead distance of 300m to 500m leads to a sub-optimality less than 1% in the energy consumption compared to the global solution. For highway driving conditions, a look-ahead distance of 1km to 1.5km leads to a sub-optimality less than 2% compared to the global solution

Convective Heat Transfer in a Pneumatic Hybrid Engine

International audienceSeveral previous studies have proven that pneumatic hybridization of an internal combustion engine is a technically viable and cost-efficient alternative to electric hybridization. Because the heat transfer process remains a first order factor while the engine operates in a motored or pneumatic mode without combustion, an accurate instantaneous heat transfer model is required in order to predict the in-cylinder pressure. This study shows that the original Woschni model is not suitable for describing the shape of the measured instantaneous heat flux versus crank angle while the engine operates in a motored pneumatic mode, because of the extinction of tumble motion near Top Dead Center (TDC). A modified form of the Woschni model is therefore proposed here that better describes the instantaneous heat flux during compression and expansion strokes, applicable to pneumatic and motored with fuel cut-off modes. First, the new constant parameter model is identified from experimental measurements performed in various motored mode conditions. Next, the pneumatic supercharged mode without combustion (ignition not performed) is investigated with the new model using the same identification values as for the motored mode. This study shows that the modified model remains fully applicable to the supercharged mode, despite of a certainly modified in-cylinder aerodynamic structure created by the opening of the charging valve under a high pressure rati

Nonlinear Model Predictive Control of the Air Path of a Turbocharged Gasoline Engine Using Laguerre Functions

International audienceObjectives in terms of pollutant emissions and fuel consumption reduction have led car manufacturers to enhance the technical definitions of combustion engines. The latter should now be considered as multiple-input multiple-output nonlinear systems with saturated actuators. This considerably increases the challenge regarding the development of optimal control laws under the constraints of constant cost reductions in the automotive industry. In the present paper, the use of a nonlinear model predictive control (NMPC) scheme is studied for the air path control of a turbocharged gasoline engine. Specifically, a zero dimension physics-based model is combined with parameterization of the future control trajectory. The use of Laguerre polynomials is shown to increase flexibility for the future control trajectory at no cost in computational requirements. This increase in flexibility leads to an improvement of the transient response of the closed-loop with respect to traditional approaches. This practical application shows that this approach makes it easier to fine-tune the NMPC scheme when dealing with engine air path control

Explicit-Ready Nonlinear Model Predictive Control for Turbocharged Spark-Ignited Engine

International audienceThe trend to reduce the engine size in automotive industry is motivated by more restrictive pollutant emissions standards. That is why engine technical definitions have become more and more complicated. The control challenge has also grown since engines are now considered as highly nonlinear multi-input multi-output systems with saturated actuators. In this context, the need for model-based control laws is bigger than ever. In this study we propose a nonlinear model predictive control strategy based on a physical engine model. Moreover, we also underline the benefit of using a thermodynamic engine term in the objective function. Finally, the design and calibration choices consciously fulfill the criterions of the use of an explicit approach for the real time implementation

Determining vehicle acceleration from noisy non-uniformly sampled speed data for control purposes

International audienceVehicle acceleration is an important variable for many automotive control applications. In this paper, we present an approach to estimate vehicle acceleration from vehicle speed data coming from the CAN (Controller Area Network) bus. The proposed method, which can be seen as an extension of the Savitzky-Golay filter to non-uniformly sampled signals, re-samples them to a constant period while filtering noise coming from different sources and also provides a proper estimation of vehicle acceleration. We also consider the frequency response of the filtering effect of the method. Finally, some practical considerations for efficient implementation of the algorithm are given

Explicit Nonlinear Model Predictive Control of the Air Path of a Turbocharged Spark-Ignited Engine

International audiencePollutant emissions and fuel economy objectives have led car manufacturers to develop innovative and more sophisticated engine layouts. In order to reduce time-to-market and development costs, recent research has investigated the idea of a quasi-systematic engine control development approach. Model based approaches might not be the only possibility but they are clearly predetermined to considerably reduce test bench tuning work requirements. In this paper, we present the synthesis of a physics-based nonlinear model predictive control law especially designed for powertrain control. A binary search tree is used to ensure real-time implementation of the explicit form of the control law, computed by solving the associated multi-parametric nonlinear problem

Synthèse unifiée de commandes robustes pour la chaine d'air des moteurs à combustion interne

Depuis la création des moteurs à combustion interne, les recherches sur les moteurs essence et diesel se sont développées indépendamment. Afin de réduire les temps et les coûts de développement d un moteur, une approche unifiée de conception serait intéressante. Dans ce cadre, le contrôle et la mise au point des moteurs à combustion interne pourrait être elle aussi unifiée. Bien évidemment, ce contrôle doit être stable, robuste vis-à-vis des disparités de fabrication, comme de fonctionnement. Cette thèse porte alors sur une démarche unifiée, pour les moteurs essence comme pour les moteurs diesel, afin d obtenir un contrôle robuste de la chaîne d air du moteur. La chaîne d air du moteur contient les éléments permettant de contrôler la quantité et les proportions d air et de gaz neutres dans le cylindre (Recirculation des gaz d échappement, papillon d admission, turbocompresseur). Cette démarche unifiée de commande, permettant de contrôler les systèmes monovariables, tout comme multivariables non carrés (nombre d entrées différent du nombre de sorties), contient plusieurs étapes : identification d un modèle du système, analyse du système permettant d en déduire une structure de contrôle, synthèse d un contrôleur autour d un nominal, vérification de la robustesse en stabilité, tests du contrôle. Le couplage des entrées vers les sorties, les non linéarités sont pris en compte lors de la synthèse du contrôleur. Cette méthode de conception a été validée sur plusieurs applications dont un moteur essence et un moteur diesel. Des résultats expérimentaux sur un banc moteur diesel haute dynamique ont montrés que la commande multivariable permettait de réduire les émissions d oxydes d azote.Since the creation of internal combustion engines, research on gasoline and diesel engines were developed independently. To reduce the time and cost of developing an engine, a unified design approach would be interesting. In this context, control and development of internal combustion engines could also be unified. Obviously, this control must be stable, robust with respect to manufacturing disparities and operating points. This thesis then focuses on a unified approach for gasoline engines as well as diesel engines, to achieve a robust of the air path. The engine air path contains the information needed to control the amount and proportions of air and neutral gases in the cylinder (exhaust gas recirculation, throttle valve, turbocharger). This unified approach to control monovariable systems, as well as non-square multivariable systems (number of inputs different from the number of outputs), consists of several steps: identification of a model of the system, system analysis to deduce a control structure, synthesis of a controller around a nominal model, check robust stability, control tests. The coupling inputs to outputs and nonlinearities are taken into account during the synthesis of the controller. This design method has been validated in several applications including a gasoline engine and a diesel engine. Experimental results on a diesel engine high dynamics test bench have shown that the multivariable control results in lower emissions of nitrogen oxides.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

Evaluation of the energy management strategies for a hybrid pneumatic engine

Cette thèse porte sur l évaluation de plusieurs stratégies de gestion d énergie pour un nouveau concept de moteur hybride pneumatique. Ce concept combine un moteur à combustion interne avec un système de stockage d énergie sous forme d air comprimée. Une soupape supplémentaire relie alors la chambre de combustion à un réservoir d air et permet un fonctionnement en mode moteur pneumatique ou pompe pneumatique (récupératif). La première stratégie, Causale, est basée sur des principes heuristiques. La deuxième, à Coefficient de Pénalité Constant, vise la minimisation d un critère énergétique global. Un coefficient de pondération permet de mettre en opposition, pour un travail donné, les coûts énergétiques d un mode pneumatique d une part et d un mode thermique d autre part. Le mode offrant le coût le plus faible sera choisi. La troisième stratégie, à Coefficient de Pénalité Variable, sur le même principe utilise un coefficient de pondération variable selon la quantité d énergie pneumatique disponible. Une stratégie, à reconnaissance de situation de conduite, permet d adapter les stratégies à la situation reconnue (par exemple, embouteillage, autoroutier). Enfin, la dernière stratégie tente de recopier la solution optimale de référence (obtenue par programmation dynamique) à l aide d un modèle. Toutes les stratégies ont été validées en simulation sur cycles standards. De plus une méthode, basée sur les chaînes de Markov, de constructions de cycle de conduite artificiels mais réalistes est proposée. Les consommations obtenues avec les différentes stratégies proposées sont comparées en référence aux consommations minimales atteignables. Les résultats montrent que 40% de gain de consommation peuvent être atteints.This thesis presents a study of several energy management strategies for a novel hybrid pneumatic engine concept. The concept combines an internal combustion engine with a system of compressed air for energy storage. An additional charge valve connects the combustion chamber to an air pressure tank, enabling the engine to function in pneumatic motor mode or as a pneumatic pump (recuperation mode). The first strategy is called Causal and implements a rule-based control technique. The second one, called Constant Penalty Coefficient, is derived from optimal control theory and is based on an equivalent consumption minimization strategy. A penalty coefficient is introduced to evaluate, for a given torque demand, the respective energy costs of the two modes, pneumatic and conventional, enabling the mode offering the lowest cost to be chosen. The third strategy, called Variable Penalty Coefficient, is based on the same principle but uses a variable penalty coefficient depending on the amount of pneumatic energy available in the compressed air tank. Another strategy investigated, called Driving Pattern Recognition, adapts the strategies to the driving situation recognized (for example, traffic jam, or highway). The last strategy studied attempts to reproduce the optimal reference solution obtained by dynamic programming, using a neural mode. All the strategies have been validated by simulation on standard driving cycles. In addition, a method based on the Markov chain process have been develop to make artificial yet realistic driving cycles. The consumptions obtained with the various strategies are compared with the minimal consumptions achievable. Results demonstrate that 40% of fuel saving can be achieved on certain cycles. Several of the strategies proposed give results that are close to optimal.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

Commande multisystème hiérarchisée pour le pilotage d'un avion autonome au sol

Pour répondre à l augmentation du trafic aérien mondial et à l amélioration de la sécurité sur les plateformes aéroportuaires, le secteur aéronautique développe de nouveaux systèmes permettant de tendre vers l autonomie complète de l avion pendant les phases de roulage au sol. Le thème de ce travail de thèse concerne l automatisation du pilotage de l avion au sol et le développement d une architecture de commande multivariable permettant de superviser l ensemble des systèmes impliqués dans ce mode de déplacement : les systèmes de motorisation et de freinage des roues principales et le système d orientation du train avant. Après une modélisation détaillée de la dynamique du système et une analyse des problématiques induites par ses non-linéarités, une architecture de commande globale est proposée. L asservissement de la dynamique angulaire des roues, pendant les phases d accélération et de freinage, est assuré par une loi de commande linéaire robuste aux incertitudes, synthétisée à l aide de la technique Q.F.T. Le pilotage de la dynamique latérale du véhicule est réalisé au moyen d un correcteur hybride feedforward-feedback. Une commande modale au premier ordre est alors mise en oeuvre afin de synthétiser un régulateur non-linéaire par planification de gains (gain-scheduling). L ensemble des boucles d asservissement de l architecture est finalement validé en réalisant un suivi automatique de trajectoire à l aide d une commande géométrique nommée follow the carrot. Les simulations représentatives de l utilisation réelle de l avion démontrent des performances satisfaisantes et permettent de valider l ensemble des solutions proposées.In the context of worldwide air traffic growth and airport security improvement, the main aeronautics actors are currently investigating new systems, strived for autonomously piloting the aircraft while taxiing ground-borne. The present thesis deals with aircraft taxiing control and the design of a multivariable control architecture aimed at supervising all the ground acting systems: driving and braking systems of main wheels and the nose landing gear steering system. A global control architecture is introduced after a detailed modelling of the system dynamics and an analysis of the issues induced by the nonlinearities. A linear Q.F.T controller is synthesised to ensure robust control against uncertainties of the wheel angular dynamics, in both driving and braking operations. The vehicle lateral dynamics is controlled by means of a feedforward-feedback hybrid controller. The latter includes a nonlinear gain-scheduled controller designed by a modal approach. All the architecture control loops are finally validated in a high level path following control, achieved with the follow the carrot geometric method. A set of representative simulations show the overall good performances and validate the whole proposed solution.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

Plate-forme d'aide à l'éco-conception de systèmes multiphysiques (démarche énergétique pour la validation et la réduction de modèles)

De nos jours, les évolutions technologiques imposent aux ingénieurs de modéliser desphénomènes toujours plus multiphysiques et complexes tout au long du processus dedéveloppement d un système : le cycle en V. Pour cela, il est primordial d avoir à disposition desoutils adaptés et performants, afin de réduire les temps de mise sur le marché, tout en obtenantdes produits plus matures et plus économes en énergie. Les travaux présentés ici décrivent lamise en place d une plate-forme de prototypage virtuel et l intérêt d intégrer des considérationsénergétiques dans toutes les étapes de la modélisation. Cette approche permet, par exemple, dequantifier l efficacité d un système et de ses composants, et donc d optimiser au plus tôt le coûténergétique d une solution technique. Nous avons, dans un second temps, souhaité répondre àla problématique du modèle le plus adapté . Après analyse des différentes méthodes deréduction de modèles, nous avons décidé de développer la méthode PEMRA permettant depallier les limitations de la méthode MORA, introduite par Louca et al. en 1997. Les variables depuissance et d énergie introduites précédemment sont utilisées pour calculer deux nouveauxcritères dans le processus de réduction de modèles, permettant de converger vers un modèleréduit plus simple et plus précis qu avec la méthode MORA. Nous montrons enfin qu enchoisissant judicieusement le signal d excitation et un critère dit de précision temporelle adapté, ilest possible, par une approche innovante à la fois énergétique et fréquentielle, de trouver unmodèle réduit mieux adapté aux exigences imposées par l utilisateur.Nowadays, technological evolutions are leading engineers to model increasingly multiphysic andcomplex phenomena throughout the systems design process: the V-cycle. Adapted and efficientsystems design tools are therefore necessary in order to reduce time-to-market, while stillensuring fully developed and energy-saving products. First, this work describes the set-up of avirtual prototyping platform and highlights the interest of integrating energetic aspects in allmodelling stages. For example, this approach enables to quantify the system and components efficiency, and therefore to optimise earlier in the process the energy consumption of a technicalsolution. Secondly, the problematic of the Proper Model has been addressed. After the study ofthe model reduction methodologies, we decide to develop PEMRA in order to compensate forlimitations of the MORA methodology, introduced by Louca et al. in 1997. The previous powerand energy variables are then used to compute two new model reduction criteria, in order toobtain a simpler and more accurate reduced model than with MORA methodology. Finally, weshow that a well-defined excitation signal and a new adapted temporal validation criterion willlead, with this innovative energy- and frequency-based approach, to a better suited reducedmodel.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF