53 research outputs found
Silicon nitride-based deep sub-λ slit for ultra-broadband THz coherent detection
No full textWe report on the characterization of a new type of CMOS-compatible device for terahertz solid-state biased coherent detection, which relies on a 1-μm-wide metallic slit embedded in a thin film of PECVD-grown silicon nitride
Evaluation de stratégies de commande pour véhicules hybride paralleles
No full textHybrid vehicles are usually propelled by one or two electric motor and an internal combustion engine. The first part of this study presents some classical mechanical arrangements and describes the prototype built at the LAMIH during a previous project. Algorithms, called control strategy, are used to choose at each sampling time the power split between the engine and the motor. Some of them rely on empiric rules and uses fuzzy controllers and other deals with more detailed energy flow analysis. Then the choice of the power split is written into the form of an optimization under constraint problem. Several algorithms based on the optimal control theory are proposed. The aim is to compute, in simulation, the control sequence that ensures the lowest fuel consumption. A new control strategy is derived from the global optimization algorithm and a second one is proposed, based on the analysis of the global optimization results. Several criterions are proposed in order to characterize speed cycles, to evaluate control strategies. A comparison of several control strategies shows that one of the proposed control strategies provides best results, closed to those of the global optimization algorithm. At last, the use of the global optimization algorithm for the choice of the mechanical arrangement and sizing the engine and the motor is explained in the last section.électriques associés à un moteur thermique. La première partie décrit les grandes familles d'architectures et le prototype réalisé au LAMIH au cours de travaux précédents. La deuxième partie est consacrée à l'étude d'algorithmes, appelés stratégies de commande, qui choisissent à chaque instant la répartition de puissance entre les deux chaînes de traction. Les approches envisagées reposent soit sur l'utilisation du formalise flou et mettent en oeuvre des règles de bon sens soit sur l'analyse plus fine des échanges énergétiques au sein du groupe motopropulseur. La répartition de puissance entre les différentes motorisations est ensuite écrite sous la forme d'un problème d'optimisation globale sous contraintes. Plusieurs algorithmes basés sur la théorie de la commande optimale sont alors proposés. L'objectif est de rechercher, en simulation, la séquence de commandes qui minimise de la consommation de carburant. Dans la dernière partie, les résultats des algorithmes d'optimisation globale sont utilisés, dans un premier temps pour proposer deux nouvelles stratégies de commande temps réel. Ensuite, une étude basée sur des critères permettant de caractériser les cycles de vitesses et les performances des stratégies de commande a notamment permis de valider les stratégies proposées. Enfin, l'utilisation des algorithmes d'optimisation globale comme outil d'aide au dimensionnement et aux choix d'architecture est illustré dans la dernière partie
Hybrid Vehicle Energy Management: Avoiding the Explicit Hamiltonian Minimization
No full textInternational audiencePontryagin's Minimum Principle provides an efficient framework for Hybrid Electric Vehicle (HEV) energy management. The control is obtained by minimizing the Hamiltonian at each instant. The whole optimization problem is then transformed into a Boundary Value Problem (BVP). For a few problems, this minimization can be solved explicitly and for most of the others, numerical methods are used. An alternative method for any convex problem is proposed. As a result, the whole hybrid vehicle optimal energy management is turned into an extended BVP
Parking_MFC.avi
No full textVideo footage of the experiments conducted for the paper "A revised look at “intelligent-PID” model free control". The experiment consists in controling the vehicle lateral motion using a model free control approach using the improved framework described in the paper.Experimental conditions are similar to those of figure 7.</div
Active Side Shafts Torsion Damping Control for Hybrid Electric Vehicles
No full textInternational audienceHybrid electric vehicles generally use an internal combustion engine and one or several electric drives. Optimization-based energy management strategies computes a power split between both the engine and the machine to minimize the fuel consumption. Nevertheless, the driving comfort is not taken into account. Due to its high torque bandwidth, the electric machine can be used to improve driving comfort. The objective of this paper is to propose the use the electric machine to actively damp the encountered side-shafts torque oscillations. The driveshaft torsional behavior is described and the corresponding comfort issues are highlighted. Simulations results have been done for the nominal case and to validate the controller behavior with respect to some un-modeled parameter variations
Hybrid vehicle energy management: singular optimal control
No full textHybrid vehicle energymanagement is often studied in simulation as an optimal control problem. Under strict convexity assumptions, a solution can be developed using Pontryagin’s minimum principle. In practice, however, many engineers do not formally check these assumptions resulting in the possible occurrence of so-called unexplained “numerical issues.” This paper intends to explain and solve these issues. Due to the binary controlled-state variable considered (e.g., switching on/off an internal combustion engine) and the use of a lookup table with linear interpolation (e.g., engine fuel consumption map), the corresponding Hamiltonian function can have multiple minima. Optimal control is not unique. Moreover, it is defined as being singular. Consequently, an infinite number of optimal state trajectories can be obtained. In this paper, a control law is proposed to easily construct a few of them
Brake and velocity model-free control on an actual vehicle
No full textInternational audienceA tuning procedure for the model-free control paradigm introduced in Fliess and Join (2013) is proposed. This controller requires an estimate of the system dynamics usually obtained using an ALIEN filter, presented in Fliess and Sira-Ramírez (2003). Several implementation issues of this ALIEN filter, such as the order of the numerical quadrature, are discussed and overcome. Finally, the control law is applied to two systems: the low-level braking system of a vehicle and its longitudinal speed control. Experimental results on a real vehicle are provided and compared with a classic PI controller
Convergence d'observateurs flous sous formes descripteurs : application à l'homme en station debout
No full textInternational audienceUne classe d'observateurs non linéaires sous forme descripteurs basée sur une modélisation de type Takagi-Sugeno (TS) est décrite. Les conditions de convergence de l'erreur de reconstruction sont obtenues sous la forme de problèmes LMI. L'intérêt de ce type de représentation est, pour certains modèles non linéaires, de réduire la conservativité des résultats classiques. Cette réduction se fait au travers de la réduction du nombre de règles du modèle TS. Une application à la biomécanique de l'homme en station debout est proposée. Un observateur à entrées inconnues est défini afin d'estimer les vitesses et couples articulaires à partir de mesures de positions obtenues par un système optoélectronique de capture du mouvement
Convergence d'observateurs flous sous formes descripteurs : application à l'homme en station debout
No full textInternational audienceUne classe d'observateurs non linéaires sous forme descripteurs basée sur une modélisation de type Takagi-Sugeno (TS) est décrite. Les conditions de convergence de l'erreur de reconstruction sont obtenues sous la forme de problèmes LMI. L'intérêt de ce type de représentation est, pour certains modèles non linéaires, de réduire la conservativité des résultats classiques. Cette réduction se fait au travers de la réduction du nombre de règles du modèle TS. Une application à la biomécanique de l'homme en station debout est proposée. Un observateur à entrées inconnues est défini afin d'estimer les vitesses et couples articulaires à partir de mesures de positions obtenues par un système optoélectronique de capture du mouvement
High order sliding mode control for hybrid vehicle stability
No full textInternational audienceThis paper tackles the problem of driving stability for a hybrid vehicle. A rear electric motor has been added to the vehicle driveline and the positive/negative torque generated by this motor affects the driving conditions. The vehicle stability control is addressed using high order sliding modes (HOSMs) control and observation techniques. Two cases are studied: yaw stability and traction control. The proposed controllers preserve the system’s safety under undesirable rear motor effects, at the same time, they cope with vehicle uncertainties. The feasibility of this platform was tested in a vehicle simulator
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