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IF=5.673; International audience; Safety systems claim an in-depth study of vehicle motion and tire-ground interaction for the design of a partially automated driving vehicle. This article addresses the quasi-linear parameter-varying Luenberger interconnected fuzzy observer to estimate both longitudinal and lateral vehicle dynamics simultaneously. In a different manner from the commonplace state of the art of vehicle state observers that consider single driving motion, the proposed approach considers the coupled dynamics with the tire-ground interaction to estimate the most important states while reducing the complexity related to the observability and conservatism. This consideration leads to a nonlinear parameter-dependent interconnected model with unmeasured premise variables. Then, the Takagi-Sugeno fuzzy form is considered to deal with the nonlinearities of the vehicle longitudinal and lateral speeds and the slip velocities as well as the steering angle. The concept of “input to state stability” is exploited using fuzzy nonquadratic Lyapunov stability arguments to guarantee the boundness of the estimation errors. A refinement has been proposed through the so-called Polya's theorem aiming to further reduce the conservativeness. Finally, performances and effectiveness of the suggested approach are evaluated through hardware experiments performed with the well-known Sherpa dynamic car simulator under real-world driving situations.

21st Congress of the International Ergonomics Association (IEA 2021), VANCOUVER, CANADA, 14-/06/2021 - 18/06/2021; International audience; Using an integrative user-centered approach, the research project aimed at designing and assessing an adaptive HMI to improve the safety and the quality of the take-over in a level-3 automated vehicle. Future autonomous driving users confirmed the need for the monitoring systems to improve safety as long as they are simple and not intrusive. They request specific information to understand and initiate appropriated actions in case of a critical situation. However, to avoid overloading and detri-mental effects, it is important that the system limits the amount of infor-mation at the right moment.

International audience; This paper proposes a novel approach for designing an assistance system via haptic joystick force feedback on an electric wheelchair using model-based shared control approach. Assistance system supports wheelchair users through haptic force at joystick which can make the user-wheelchair interaction becomes more intuitive. Firstly Tagaki-Sugeno fuzzy model is used to build an augmented model of user-wheelchair system to deal with non-linear nature of system. Unknown input observers are developed to estimate wheelchair position errors which are considered as user intention based on joystick motions. Fuzzy logic optimal controller is synthesized by Linear Matrix Inequalities method to provide assistance haptic forces feedback to user via joystick. Simulation and experimental results show that this assistance system can predict the desired motion of user and reduce user hand force thanks to haptic force at joystick.

International audience; Understanding and predicting the behavior of the powered wheelchair users play an important role in developing the driver assistance systems for the intelligent wheelchair. This article presents a model of wheelchair users, from the point of view of control engineering, based on the interaction between the human hand-joystick and the lumped-parameter model of the human hand muscle system. The interaction between hand and joystick is represented by a robot arm with a four-bar closed-chain mechanism. This mechanism is operated by four musculotendon units based on Hill's muscle model. This configuration allows simulating whole motions of the joystick as well as the evolutions of muscle activities during maneuvering the powered wheelchair. The advantage of this model is the integration of the biomechanical parameters of the muscular system of the human hand, which is very useful for simulating the defects related to the degree of physical impairment of wheelchair users. To validate the proposed model, we compare the simulation outputs of the user model with the previously published experimental results in the framework of the Wheelchair Skills Test (v. 4.1). The simulation results show that the proposed model can reflect the difficulties at the biomechanical level of users in driving the wheelchair.

This paper provides a new solution for path following control of autonomous ground vehicles. $\mathcal {H}_{2}$ control problem is considered to attenuate the effect of the road curvature disturbance. To this end, we formulate a standard model from the road-vehicle dynamics, the a priori knowledge on the road curvature, and the path following specifications. This standard model is then represented in a Takagi–Sugeno fuzzy form to deal with the time-varying nature of the vehicle speed. Based on a static output feedback scheme, the proposed method allows avoiding expensive vehicle sensors while keeping the simplest control structure for real-time implementation. The concept of $\mathcal {D}-$ stability is exploited using Lyapunov stability arguments to improve the transient behaviors of the closed-loop vehicle system. In particular, the physical upper and lower bounds of the vehicle acceleration are explicitly considered in the design procedure via a parameter-dependent Lyapunov function to reduce drastically the design conservatism. The proposed $\mathcal {H}_{2}$ design conditions are expressed in terms of linear matrix inequalities (LMIs) with a single line search parameter. The effectiveness of the new path following control method is clearly demonstrated with both theoretical illustrations and hardware experiments under real-world driving situations.

International audience; A manual wheelchair (MWC) is an indispensable support for a person with reduced mobility. The researches on improving performance of MWC, therefore, should be validated by a reliable simulation platform, which allows simulating the MWC operation in virtual reality (VR), before being tested on real conditions. This research aims to provide a fully-constituted dynamical model of MWC which will be used in simulator platform to simulate the real movements of wheelchair and to generate the force feedback (haptics) during the push phase (hand-to-rim contact). With focus on the performance of wheelchair at the low-speed region, this model comprised the tire-road contact forces and the influence of the front free caster wheels. Validation experiments simulating several typical daily maneuvers of the manual wheelchair were conducted. Compared to previous research, the new model presented in this paper overcomes the problem of overestimating the the yaw rate.

IF=3.576; International audience; Abstract This paper presents a new control method for autonomous vehicles. The design goal is to perform the automatic lane keeping under multiple system constraints, namely actuator saturation of the steering system, roads with unknown curvature and uncertain lateral wind force. Such system constraints are explicitly taken into account in the control design procedure. To achieve this goal, we propose a new constrained Takagi–Sugeno fuzzy model-based control method using fuzzy Lyapunov control framework. The resulting non-parallel distributed compensation controller is able to handle not only various system constraints but also a large variation range of vehicle speed. In particular, Taylor’s approximation method is exploited to reduce not only the numerical complexity for real-time implementation but also the conservatism of the results. The design conditions are strictly expressed in terms of linear matrix inequalities which can be efficiently solved with available numerical solvers. The effectiveness of the proposed control method is demonstrated through both simulation and hardware experiments with various driving scenarios.

International audience; The shared control between human driver and autonomous controller for vehicles has been evaluated over several driving conditions such as cruise control, lane keeping/ lane change assist, highway driving etc. Typically, these approaches synthesize controllers based on linear vehicle models integrated with visual cues based driver model. In this work, to consider the aspect of tire-friction non-linearity, Brush-Tire force model has been considered. Further, to address conflict between human driver and autonomous controller during typical maneuvers, a novel sharing parameter was introduced in the proposed robust sliding mode based control design. Subsequently, the proposed shared control technique is validated thru numerical simulations over the Satory test track, with lateral wind force and road curvature considered as disturbance. Discussions on influence of varying road-friction conditions and sharing parameter proposed is also presented.

International audience; While safety is a critical criterion of the autonomous wheelchair and attracted much attention over the last few decades, the user comfort has not been considered as an important factor yet. Therefore, this article proposes a path following controller for an electric powered wheelchair (EPW) which aims to assure the comfort and safety of users during the navigation tasks. This controller is a combination of transverse feedback linearization (TFL) and model predictive control (MPC) techniques. The main contribution of this work is to consider the jerks and acceleration of EPW, directly linked to the user's relaxation, as constraints in solving an optimal control problem to design MPC controller. TFL allows to achieve path invariance properties, which is useful for path following task. The simulations are conducted in both circular path and arbitrary path in a typical office environment. Simulation results illustrate the perspective of the proposed approach where the desired path is well followed and the constraints on user's comfort are respected.

International audience; This paper is concerned with a new control method which can share the control authority between a human driver and a lane keeping assist system. Based on the concept of multiple controller switching, this shared control method is composed of two levels: operational and tactical. At the operational level, two local optimal-based controllers are designed to satisfy their own predefined control goals. At the tactical level, a supervisor is designed to orchestrate a smooth control authority transition between two local controllers. The closed-loop properties of the human-in-the-loop vehicle system are guaranteed via Lyapunov stability arguments. In particular, the design of both local controllers is recast as a convex optimization problem, easily solved with numerical solvers. The effectiveness of the proposed shared control method is experimentally validated with a human driver and a dynamic driving simulator.

International audience; In this paper an intelligent robust feedback control approach is proposed for the nonlinear disturbed suspension system. The nonlinear controller is formulated based on the integral higher order sliding mode with control parameters optimized using Particle Swarm Optimization technique. A novel classifier invariant to changes in control parameters is developed to detect the road class. Subsequently in the real time, based on system responses the road level is detected by the classifier and accordingly the optimized control parameters are selected to implement the controller. The closed loop stability of the proposed approach is established and simulation results for different road classed are presented to show improvement in passenger comfort.

International audience; This paper describes the design of a new haptic shared steering control framework for automated driving systems. In this framework, the shared control problem is formulated as a constrained optimization problem which is solved online by a model predictive controller. Without driver's intervention, the system assumes automatic lane-keeping control. When the driver takes over control, by adapting the weight on the stage cost and implementing dynamic constraints, the framework ensures seamless control transfer from the system to the driver while conveying potential hazards through haptic feedback. Simulation results are presented to demonstrate the ability of this framework to handle control allocation and hazard warning.

International audience; Conflicts between the driver and systems for automated steering are important issues that affect the safety of the driver and the acceptability of the system. This paper presents a new framework for shared lateral control on highway driving using trajectory planning. The core idea of this work is to account for the driver’s steering torque in the trajectory planning level in order to adjust the system’s desired trajectory in a way that better suits the driver intention. By doing so, the system would strive towards the position aimed by the driver thus helping him to swerve within the lane with reduced effort and conflicting torques. The advantage of the proposed approach is demonstrated on a driving simulator study with a scenario of avoiding obstacles undetected by the system.

IF=7.168; International audience; This paper addresses the shared lateral control between a human driver and a lane keeping assist system of intelligent vehicles for both lane keeping and obstacle avoidance. This control issue is very challenging in today's automotive industry due to the human-machine interaction involved in the control design. In this paper, we propose a new approach to consider such an interaction via a fictive driver activity parameter introduced into the road-vehicle system. Hence, the steering assistance actions can be computed according to the driver's real-time behaviors. The Takagi-Sugeno fuzzy control approach is proposed to deal with the time-varying driver activity parameter and vehicle speed. Especially, the concept of robust invariant set is exploited using Lyapunov arguments to handle theoretically both system state and control input limitations. Considering these system constraints in the control design procedure aims to improve the driver's safety and comfort. Experimental tests with a human driver and an advanced interactive dynamic driving simulator are conducted to show the effectiveness of the proposed method.

International audience; This article introduces a functional architecture of an automated driving system defined by taking into account the theoretical knowledge on the driving task modeling and the principles of humanmachine cooperation. The necessary functionalities to ensure the interaction and cooperation between the system and the driver who share the driving task on the operational, tactical and strategic levels were gathered. A multi-level cooperative interaction concept to continuously share control between the driver and the system is introduced. The architecture modules have been implemented and tested in an experiment on a driving simulator with an expert driver. Results show an improved interaction with the driver thanks to the continuous and dynamic interference management.

This paper describes an adaptive vehicle longitudinal trajectory prediction method for automated highway driving applications. A major strength of this method is that it can cope with highly dynamic situations in which the constant acceleration (CA) assumption cannot guarantee long term prediction accuracy. In this method, a quintic polynomial is used to model the longitudinal dynamics of a vehicle that is maneuvering. The decision to switch to it from the CA model is formulated as a maneuver detection problem. A maneuver is detected through monitoring measurement innovations of a Kalman filter that tracks target longitudinal states. The longitudinal jerk, as a dynamic characteristic of a maneuver is also estimated from measurement innovations. Finally the estimated jerk and context information are incorporated into the quintic polynomial model. The overall approach was tested on recorded human driving data from a simulator in a dynamic highway merging scenario. The results show the proposed method has higher prediction accuracy than the CA based method in such a dynamic scenario.

International audience; This paper is devoted to the development of a shared lateral control strategy for a Driver Steering Assist System (DSAS) that can share the authority with the driver. Up to now, this control issue is still an open research subject in automotive industry due to the complex interactions according to different driving situations between the Human (driver) and the Machine (DSAS). In this work, such interactions are handled by introducing into the vehicle system a fictive time-varying term representing the driver activity. In this way, the actions of the DSAS are computed in function of the driver behaviors (actions and intentions). Using Takagi-Sugeno control technique in the framework of Lyapunov stability theorem, the designed controller is able to handle a large range of variation of vehicle longitudinal speed. Moreover, the proposed controller requires only measured output signals for the design procedure and implementation. The effectiveness of the proposed method is demonstrated with different driving scenarios.

International audience; This paper is devoted to the development of a new saturated control law for constrained Takagi-Sugeno fuzzy systems. These systems are subject to both control input and state constraints and also persistent disturbances bounded in amplitude. The design procedure is formulated through linear matrix inequalities (LMIs) form which can be solved by means of convex optimization techniques. Based on the concept of robust invariant set in non-quadratic Lyapunov control framework, the proposed method provides a characterization of the closed-loop domain of attraction. Numerical example is given to demonstrate the interests of the proposed methodology.

International audience; In this work, an Unknown Input Proportional Multi-Integral Takagi-Sugeno (UIPMIT-S) observer is designed to estimate both the lateral vehicle states and the driver's torque considered as unknown input. The observer design is formulated in LMI framework to lead all the T-S observer sub-models poles in a D-stable region. The LMI constraints related to the D-stable region force the convergence of the estimation errors with a controllable decay rate and limit overshooting in the transient phase. The proposed approach is validated first, in numerical simulations, and after using the LAMIH driving dynamic simulator SHERPA.

International audience; In this work, a driving assistance system (DAS) sharing the control of a vehicle with a human driver is proposed. The cooperation degree between the DAS and the human driver is in the center of this work with the aims of reducing conflict between them. A lane keeping driver model is added to the road-vehicle one in order to achieve this goal. Fuzzy Takagi-Sugeno (T-S) optimal controller is driven considering a varying vehicle longitudinal velocity. The system is evaluated regarding both the human-machine interaction point of view in hazardous situation and the lane keeping performance. Firstly, numerical simulations carried out in Matlab/Simulink are illustrated, and after, the proposed DAS is tested on the LAMIH-SHERPA dynamic simulator with a human driver. The obtained results show the effectiveness of the proposed approach.

This thesis focuses on the design, implementation, and evaluation of a customizable assistance system for power wheelchair users. The system is based on a shared control approach interacting with the user via a force feedback joystick. The proposed assistance system targets three main objectives: i) Predict the user’s intention using the movements of the joystick; ii) Reduce the user’s effort to manipulate the joystick during the navigation task; iii) Assist the user to avoid the obstacle while resolving the conflict between the user’s decision and the intention of the system. At the operational level, this system estimates user intention using linear observers with unknown inputs. The TagakiSugeno model-based fuzzy control and linear matrix inequalities are used to design the shared controller which provides the assistance torques to the joystick to reduce user efforts. At the tactical level, we have proposed conflict-risk management functions to predict potential collisions, to find alternative trajectories to avoid these collisions and to communicate them to the user via the haptic joystick. The experimental results based on a virtual reality-based simulator validate the proposed assistance system. Manual torques for manipulating the joystick have been reduced and the level of assistance can be adjusted via the model settings. The haptic torques assist the user to avoid the obstacles while retaining his authority, that is, his ability to overrule the system suggestions. To validate the proposed shared control approach, we have developed a comprehensive dynamic wheelchair model that is integrated into an experimental virtual reality platform in our laboratory. The goal of this model is to reproduce the real movements of wheelchair in the virtual reality environment and therefore to increase the sense of movements for the wheelchair user on the simulator platform. This model considers the interaction of tire-road contact, the effects of the free front casters and the yaw resistance torques at low speeds. The experimental results confirmed the ability of the proposed model to reproduce the dynamic behavior of the wheelchair where the model responses are consistent with the real recorded data. To characterize the hand-joystick interaction which aims to personalizing the assistance system according to the user impairments, this thesis proposes a biomechanical model which inherited a five-bar robot arm mechanism to mimic the motions of the joystick and the user’s hand. This mechanism is operated by four Hill’s muscle models which allow to reflect the characteristic of user hand muscle properties. The simulation results showed the different evolutions of hand muscles activation level depending on the hand muscles biomechanical parameters.; Cette thèse se concentre sur la conception, la mise en œuvre et l’évaluation d’un système d’assistance personnalisable pour les utilisateurs d’un fauteuil roulant électrique. Le système est basé sur une approche de commande partagée interagissant avec l’usager via un joystick à retour de force. Le système d’assistance proposé cible trois objectifs principaux : i) Prédire l’intention de l’utilisateur à l’aide des mouvements du joystick ; ii) Réduire l’effort de l’utilisateur pour manipuler le joystick pendant la tâche de navigation ; iii) Aider l’utilisateur à éviter l’obstacle tout en résolvant le conflit entre la d´décision de l’utilisateur et l’intention du système. Au niveau opérationnel, ce système estime l’intention de l’utilisateur en utilisant les observateurs linéaires à entrées inconnues. La commande floue de type Tagaki-Sugeno et les inégalités matricielles linéaires sont utilisées pour concevoir le contrôleur partagé qui fournit les couples d’assistance au joystick afin de réduire les efforts de l’utilisateur. Au niveau tactique, nous avons proposé des fonctions de gestion des risques-conflits permettant de prévoir les collisions potentielles, de rechercher les trajectoires alternatives permettant d’éviter ces collisions et de les communiquer à l’utilisateur via le joystick haptique. Les résultats expérimentaux basés sur un simulateur à base de réalité virtuelle valident le système d’assistance proposé. Les couples manuels pour manipuler le joystick ont été réduits et le niveau d’assistance peut être ajusté via les paramètres du modèle. Les couples haptiques ont guidé l’utilisateur pour éviter les obstacles tout en conservant son autorité, c’est-`a-dire sa possibilité d’annuler les suggestions du système. Pour valider l’approche de contrôle partagé proposée, nous avons développé un modèle dynamique complet de fauteuil roulant qui est intégré dans une plateforme expérimentale de réalité virtuelle dans notre laboratoire. Le but de ce modèle est de reproduire les mouvements réels du fauteuil roulant dans l’environnement de réalité virtuelle et donc d’augmenter le sens des mouvements pour l’utilisateur du fauteuil roulant sur la plateforme du simulateur. Ce modèle prend en compte l’interaction de contact pneu-route, les effets des roulettes avant libres et les couples de résistance au lacet à basse vitesse. Les résultats expérimentaux ont permis de valider le modèle proposé, les réponses du modèle étant cohérentes avec les données réelles enregistrées. Pour caractériser l’interaction main-joystick qui vise à personnaliser le système d’assistance en fonction des déficiences de l’utilisateur, cette thèse propose un modèle biomécanique qui s’inspire d’un mécanisme de bras robotisée à cinq segments pour imiter les mouvements du joystick et de la main de l’utilisateur. Ce mécanisme est opéré par quatre modèles musculaires de Hill qui permettent de refléter la caractéristique des propriétés musculaires de la main de l’utilisateur. Les résultats de la simulation ont montré les différentes évolutions du niveau d’activation des muscles de la main en fonction des paramètres biomécaniques des muscles de la main.

Given rapid advancement of automated driving (AD) technologies in recent years, major car makers promise the commercialization of AD vehicles within one decade from now. However, how the automation should interact with human drivers remains an open question. The objective of this thesis is to design, develop and evaluate interaction principles for AD systems that can cooperate with a human driver. Considering the complexity of such a human-machine system, this thesis begins with proposing two general cooperation principles and a hierarchical cooperative control architecture to lay a common basis for interaction and system design in the defined use cases. Since the proposed principles address a dynamic driving environment involving manually driven vehicles, the AD vehicle needs to understand it and to share its situational awareness with the driver for efficient cooperation. This thesis first proposes a representation formalism of the driving scene in the Frenet frame to facilitate the creation of the spatial awareness of the AD system. An adaptive vehicle longitudinal trajectory prediction method is also presented. Based on maneuver detection and jerk estimation, this method yields better prediction accuracy than the method based on constant acceleration assumption. As case studies, this thesis implements two cooperation principles for two use cases respectively. In the first use case of highway merging management, this thesis proposes a cooperative longitudinal control framework featuring an ad-hoc maneuver planning function and a model predictive control (MPC) based trajectory generation for transient maneuvers. This framework can automatically handle a merging vehicle, and at the mean time it offers the driver a possibility to change the intention of the system. In another use case concerning highway lane positioning and lane changing, a shared steering control problem is formulated in MPC framework. By adapting the weight on the stage cost and implementing dynamic constraints online, the MPC ensures seamless control transfer between the system and the driver while conveying potential hazards through haptic feedback. Both of the designed systems are evaluated through user tests on driving simulator. Finally, human factors issue and user’s perception on these new interaction paradigms are discussed.; Face à l’évolution rapide des technologies nécessaires à l’automatisation de la conduite au cours de ces dernières années, les grands constructeurs automobiles promettent la commercialisation de véhicules autonomes à l’horizon 2020. Cependant, la définition des interactions entre les systèmes de conduite automatisée et le conducteur au cours de la tâche de conduite reste une question ouverte. L'objectif de cette thèse est de concevoir, développer et évaluer des principes de coopération entre le conducteur et les systèmes de conduite automatisée. Compte tenu de la complexité d'un tel Système Homme-Machine, la thèse propose, en premier lieu une architecture de contrôle coopératif hiérarchique et deux principes de coopération généraux sur deux niveaux dans l’architecture qui serviront ensuite de base commune pour la conception des systèmes coopératifs développés pour les cas d’usages définis. Afin d’assurer une coopération efficace avec le conducteur dans un environnement de conduite dynamique, le véhicule autonome a besoin de comprendre la situation et de partager sa compréhension de la situation avec le conducteur. Pour cela, cette thèse propose un formalisme de représentation de la scène de conduite basé sur le repère de Frenet. Ensuite, une méthode de prédiction de trajectoire est également proposée. Sur la base de la détection de manœuvre et de l'estimation du jerk, cette méthode permet d’améliorer la précision de la trajectoire prédite comparée à celle déterminée par la méthode basée sur une hypothèse d'accélération constante. Dans la partie d’études de cas, deux principes de coopération sont mis en œuvre dans deux cas d’usage. Dans le premier cas de la gestion d’insertion sur autoroute, un système de contrôle longitudinal coopératif est conçu. Il comporte une fonction de planification de manœuvre et de génération de trajectoire basée sur la commande prédictive. En fonction du principe de coopération, ce système peut à la fois gérer automatiquement l’insertion d’un véhicule et donner la possibilité au conducteur de changer la décision du système. Dans le second cas d'usage qui concerne le contrôle de trajectoire et le changement de voie sur autoroute, le problème de partage du contrôle est formulé comme un problème d’optimisation sous contraintes qui est résolu en ligne en utilisant l’approche de la commande prédictive (MPC). Cette approche assure le transfert continu de l’autorité du contrôle entre le système et le conducteur en adaptant les pondérations dans la fonction de coût et en mettant en œuvre des contraintes dynamiques en ligne dans le modèle prédictif, tout en informant le conducteur des dangers potentiels grâce au retour haptique sur le volant. Les deux systèmes sont évalués à l’aide de tests utilisateur sur simulateur de conduite. En fonction des résultats des tests, cette thèse discute la question des facteurs humains et la perception de l'utilisateur sur les principes de coopération.