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When manually steering a car, the driver’s visual perception of the driving scene and his or her motor actions to control the vehicle are closely linked. Since motor behaviour is no longer required in an automated vehicle, the sampling of the visual scene is affected. Autonomous driving typically results in less gaze being directed towards the road centre and a broader exploration of the driving scene, compared to manual driving. To examine the corollary of this situation, this study estimated the state of automation (manual or automated) on the basis of gaze behaviour. To do so, models based on partial least square regressions were computed by considering the gaze behaviour in multiple ways, using static indicators (percentage of time spent gazing at 13 areas of interests), dynamic indicators (transition matrices between areas) or both together. Analysis of the quality of predictions for the different models showed that the best result was obtained by considering both static and dynamic indicators. However, gaze dynamics played the most important role in distinguishing between manual and automated driving. This study may be relevant to the issue of driver monitoring in autonomous vehicles.

International audience; During highly automated driving, drivers no longer physically control the vehicle but they might need to monitor the driving scene. This is true for SAE level 2, where monitoring the external environment is required; it is also true for level 3, where drivers must react quickly and safely to a take-over request. Without such monitoring, even if only partial, drivers are considered out-of-the-loop (OOTL) and safety may be compromised. The OOTL phenomenon may be particularly important for long automated driving periods during which mind wandering can occur. This study scrutinized drivers’ visual behaviour for 18 min of highly automated driving. Intersections between gaze and 13 areas of interest (AOIs) were analysed, considering both static and dynamic indicators. An estimation of self-reported mind wandering based on gaze behaviour was performed using partial least squares (PLS) regression models. The outputs of the PLS regressions allowed defining visual strategies associated with good monitoring of the driving scene. This information may enable online estimation of the OOTL phenomenon based on a driver’s spontaneous visual behaviour.

International audience; This paper presents a methodology for the systematic synthesis of haptic shared control (HSC) of a car. This HSC design is based on a two-part architecture. The first part is a trajectory generator that provides a reference trajectory to the second part, which is a static output feedback. In this paper, the haptic shared control is used as an lane keeping assist system (LKA); hence, the reference trajectory is chosen to fulfill this function. The main contribution of this article is related to the combination of the H2/H∞ feedback synthesis. This, involves an H2 criterion quantifying the sharing level and quality as an objective function, and H2/H∞ constraints for lane-keeping performance, driver comfort and robustness. The control design relies on a driver cybernetic model, which decreases conflicts between the assistance and the driver. A systematic method to tune criterion and constraints is described, enabling the attainment of desired lane-following and shared-control performance. The proposed methodology facilitates the design of lateral assistance, ensuring stability and guaranteed performance regardless of the prescribed level of sharing between the actions of the driver and the automaton. The shared control between human driver and automation for the lane keeping task over the Satory test track with the sharing level adaptation is then shown for the validation of the proposed architecture. This work introduces perspectives on smooth transitioning between manual and autonomous driving modes.

International audience; This article presents an activity analysis carried out in an aeronautical factory. The representation of the real process and the operators’ representations were identified. The representation of the real process was elaborated using an abstraction hierarchy, as described by the ecological interface design framework. The operators’ representations were extracted through interviews and observations and described in terms of schemes. The analysis revealed that operators in the studied factory used misleading schemes (i.e., false representations) to organize their activities, resultingin poor performance.We conclude by offering possible remedies, including training aimed at inhibiting the misleading scheme and a simulation tool to convey a more accurate representation.

International audience; When negotiating bends car drivers perform gaze polling: their gaze shifts between guiding fixations (GFs; gaze directed 1-2 s ahead) and look-ahead fixations (LAFs; longer time headway). How might this behavior change in autonomous vehicles where the need for constant active visual guidance is removed? In this driving simulator study, we analyzed this gaze behavior both when the driver was in charge of steering or when steering was delegated to automation, separately for bend approach (straight line) and the entry of the bend (turn), and at various speeds. The analysis of gaze distributions relative to bend sections and driving conditions indicate that visual anticipation (through LAFs) is most prominent before entering the bend. Passive driving increased the proportion of LAFs with a concomitant decrease of GFs, and increased the gaze polling frequency. Gaze polling frequency also increased at higher speeds, in particular during the bend approach when steering was not performed. LAFs encompassed a wide range of eccentricities. To account for this heterogeneity two sub-categories serving distinct information requirements are proposed: mid-eccentricity LAFs could be more useful for anticipatory planning of steering actions, and far-eccentricity LAFs for monitoring potential hazards. The results support the idea that gaze and steering coordination may be strongly impacted in autonomous vehicles.

This study investigates a real-time identification of a LPV Cybernetic Driver Model (CDM), using the Unscented Kalman Filter (UKF). Unlike an iterative identification, dealing with packets of input-output data, the method considered is recursive identification dealing with the actual input-output data, making explicit the parametric changes along time. The two identification schemes are implemented and the cybernetic driver model capability to predict or to estimate the driver steering was evaluated. The possibility of the recursive identification, when applied to the cybernetic model, to help for distraction diagnosis is finally evoked. The variations of the driver model parameters are shown to be significantly associated with driver distraction.

This paper reviews a set of scientific studies on how driver modelling may serve as the basis for designing advanced driving assistance systems. The work was aimed at explicitly representing the human visual and motor processes involved in the control of steering, and took into account current knowledge in the behavioural sciences. The nature and structure of the model, and its calibration using experimental data (identification), were addressed. Two design applications were considered: 1) estimating the driver state in various conditions of distraction and 2) building an automatic controller for haptic shared control of the steering wheel.

International audience; This study investigated human-machine cooperation when driving with different degrees of a shared control system. By means of a direct intervention on the steering wheel, shared control systems partially correct the vehicle's trajectory and, at the same time, provide continuous haptic guidance to the driver. A crucial point is to determine the optimal level of steering assistance for effective cooperation between the two agents. Five system settings were compared with a condition in which no assistance was present. In addition, road visibility was manipulated by means of additional fog or self-controlled visual occlusions. Several performance indicators and subjective assessments were analyzed. The results show that the best repartition of control in terms of cooperation between human and machine can be identified through an analysis of the steering wheel reversal rate, the steering effort and the mean lateral position of the vehicle. The best cooperation was achieved with systems of relatively low-level haptic authority, although more intervention may be preferable in poor visibility conditions. Increasing haptic authority did not yield higher benefits in terms of steering behavior, visual demand or subjective feeling.

International audience; This paper presents an advanced driver assistance system (ADAS) for lane keeping, together with an analysis of its performance and stability with respect to variations in driver behavior. The automotive ADAS proposed is designed so as to share control of the steering wheel with the driver in the best possible way. Its development was derived from a H2-preview optimization control problem, which is based on the global driver-vehicle-road (DVR) system. The DVR model makes use of a cybernetic driver model so as to take into account any driver-vehicle interactions. Such a formulation allows to: i) consider driver-assistance cooperation criteria in the control synthesis, ii) improve the performance of the assistance as a cooperative copilot, and iii) analyze the stability of the whole system in the presence of driver model uncertainty. The results have been validated experimentally with one participant using a fixed-base driving simulator. The developed assistance system improved lane-keeping performance and reduced the risk of a lane departure accident. Good results were obtained using several criteria for human-machine cooperation. Poor stability situations were successfully avoided thanks to the robustness of the whole system in spite of a large range of driver model uncertainty.

International audience; The present study compared two distinct approaches to designing driving assistance devices. These devices aim to facilitate steering responses by delivering directional pulses on the steering wheel when lane departure is imminent. In one case, the aim is to prime the corrective gesture through a haptic cue in the direction of the lane centre (motor priming). The other approach consists of eliciting a compensatory reflex reaction by means of a jerk of the steering wheel in the opposite direction. Central to this investigation are the safety benefits of the devices and the ability of drivers to remain in full control of their steering responses. The steering behaviour of 18 participants during near lane departure in bends and in straight lines was analysed. The strength and direction of haptic cueing was manip- ulated. The results show that drivers were always able to control the direction of the steer- ing response when the haptic cue was delivered. No reflex counteraction was observed, whatever the strength or the direction of the stimulus. The fastest responses were observed when the cue was directed toward lane departure, especially when cueing was strong. However, these did not necessarily lead to the fastest returns to a safe position in the lane when compared with motor priming toward the lane centre. The latter yielded improved manoeuvre execution as soon as the steering movement was initiated. These results are discussed in relation to the sensorimotor and cognitive processes involved in steering behaviour. Their implications for the design of haptic-based lane departure warning sys- tems are considered.

International audience; Within the context of more and more autonomous vehicles, an automatic lateral control device (AS: Automatic Steering) was used to steer the vehicle along the road without drivers’ intervention. The device was not able to detect and avoid obstacles. The experiment aimed to analyse unexpected obstacle avoidance manoeuvres when lateral control was delegated to automation. It was hypothesized that drivers skirting behaviours and eye movement patterns would be modified with automated steering compared with a control situation without automation. Eighteen participants took part in a driving simulator study. Steering behaviours and eye movements were analysed during obstacle avoidance episodes. Compared with driving without automation, skirting around obstacles was found to be less effective when drivers had to return from automatic steering to manual control. Eye movements were modified in the presence of automatic steering, revealing further ahead visual scanning of the driving environment. Resuming manual control is not only a problem of action performance but is also related to the reorganisation of drivers’ visual strategies linked to drivers’ disengagement from the steering task. Assistance designers should pay particular attention to potential changes in drivers’ activity when carrying out development work on highly automated vehicles.

Aims Lane departures while driving a car may be caused directly by errors in steering behaviour and indirectly as a consequence of driver distraction. Designing advanced driving assistance systems (ADAS) is a way to avoid these situations. One of the key problems is to monitor and predict driver behaviour in order to make the ADAS intervene in a timely and efficient way. Our approach to achieve this goal is to incorporate a driver model in the design process. The model represents the visual and motor determinants of steering control. It has been used as the foundation of two types of ADAS: 1. a haptic shared control system that exerts forces on the steering wheel in such a way that the automation blends into the driver’s sensorimotor control loop, providing continuous support to lane keeping, and 2. a method of distraction estimation based on the comparison between steering behaviour and the model prediction. Methods Based on current knowledge of human sensorimotor functions, the model represents the visual anticipation of the road curvature fed by the angular deviation of a far point, the visual compensation of lateral position error fed by the angular deviation of a near point, and a neuromuscular system that transforms the output of the visual subsystem into a steering wheel torque. For haptic shared control, the approach consisted in designing a control law that optimizes performance and cooperation criteria, taking into account the predictions of the driver model. A comparison was performed between the driver behaviour when using this system and when using a shared control law that did not incorporate a driver model. For distraction estimation, an identification of the driver model’s parameters was conducted in five different distraction conditions: no distraction and cognitive, visual, motor and visuomotor distractions. The torque prediction error and the parameters values were analysed. Results The results concerning haptic shared control suggest that cooperation between the driver and the automation can be improved by the inclusion of the driver model in the control law. In particular, when the level of haptic authority was set at a high level, the driver acted 27% more in coherence with the system. For the second application, the results show that the model prediction error is commensurate to a modification of steering behaviour caused by distraction. The parametric analysis suggests that an online identification of the model may be used to some extent to discriminate between different types of distraction. Conclusions Adopting a model-based approach to design ADAS is promising. The current model is limited to the representation of sensorimotor processes in humans. As such, it is adapted to be used in the context of real-time control embedded systems. In the future, it could be extended by incorporating a tactical analysis of the driving context.

This paper describes a newly developed driver model that focuses on the control of car steering. The model represents visual anticipation of road curvature and compensation of lateral positioning error. It also incorporates a neuromuscular system, inspired by Hoult and Cole (2008), including an internal model of the steering system compliance, muscle co-activation by α and γ signals and the stretch reflex. Preliminary driving simulator experiments with five participants showed that the identification of model parameters yielded consistent results. Moreover, the model was able to steer the driving simulator by itself and showed a behavior similar to that of the human driver who provided the data for parameter identification. This model may be used for the design of automation for shared control of steering.

In the perspective of full-windshield HUD in cars, this study investigated whether adding a guidance cue in the visual scene influences drivers' gaze strategies and steering behavior. Participants negotiated a series of bends with or without a visual beacon positioned on the tangent point or close to it. Results revealed that the stability of steering was improved when tracking of the beacon was enforced. The visual cue was not spontaneously used by the drivers and gaze strategy only showed minor changes in that case.

International audience; The goal of this study was to examine the effects of visual roll tilt on gaze and riding behavior when negotiating a bend using a motorcycle simulator. To this end, experienced motorcyclists rode along a track with a series of right and left turns whilst the degree of visual roll tilt was manipulated in three different conditions. Gaze behavior was analyzed by using the tangent point as a dynamic spatial reference; the deviation of gaze to this particular point was computed in both the horizontal and vertical directions. Steering control was assessed in terms of the lateral positioning, steering stability and number of lane departures. In the no-roll condition, the motorcyclists tracked a steering point on the road ahead, which was compatible with the hypothesis of ‘‘steer where you look” behavior. In the roll condition, our results revealed that the horizontal distribution of gaze points relative to the tangent point was preserved. However, significantly more fixations were made further ahead of the tangent point in the vertical direction. This modification of visual behavior was coupled with a degradation in steering stability and an offset in lateral positioning, which sometimes led to lane departures. These results are discussed with regard to models of visual control of steering for bend negotiation.

International audience; This study addressed the question of potential disorienting effects associated to head-mounted displays, by investigating the influence of a head-fixed visual frame on the perception of the vertical when the head is tilted in the frontal plane. Subject performance in indicating the vertical was contrasted with the effect of an earth-fixed visual frame as well as with the effect of tilting the head without a frame. With the tilted frames, subjects set the rod in an intermediate direction between the gravitational vertical and the orientation of the frame. Errors were strikingly larger with a head-fixed visual frame during head tilt than with a tilted earth-based frame. The increased effect cannot be attributed to the addition of a postural effect, due to the head being tilted. Moreover, continuous vision of the frame when its orientation changed improved performance only when the head and the frame were dissociated, i.e., with an earth-based frame. Those results suggest that integrating visual information in the head-centric reference frame is crucial for spatial orientation. This property of the perceptual system should be taken into account in the design of head-mounted displays for aeronautics.

Designing a human-machine interface for a manufacturing process requires a good knowledge of both the work domain and the operators' representation. Ecological Interface Design (EID) offers some interesting tools that can be of help in the design process. The literature on cognitive control also offers a good understanding of operators' cognitive resources. Analysing the activity of both expert and novice operators through these two frameworks may help us to better understand the differences between them. A three-step protocol was followed: 1. the elaboration of a means-end hierarchy, 2. the extraction of schemes via interviews, and 3. the evaluation of the behavioural manifestation of schemes. In the present case study, interviews revealed that both the novice and expert operators of a manufacturing process shared a representation of the global process. However, in contrast with the expert operators, the novice operators did not develop an operative scheme that related to the machine. The results will be used as a basis for the design of a human-machine interface that will aid them to do so.

This paper investigates the possibility of using objective indicators to predict the subjective evaluation of a driver in a simulator. Situations of loss of adherence (LOA) were controlled and modulated in intensity and duration on a static and on a dynamic simulator (with and without a motion base). Multiple regression analyses were performed using the subjective evaluation of participants as the dependent variable, and the objective physical variables of the interaction driver/vehicle as the independent variables. The results assigned the most contributive variables to the accuracy of the model’s prediction for each subjective item, lateral acceleration and yaw rate for “control feeling” for instance. They also underlined the consistency of our approach and the influence of motion rendering on the perception of LOA intensity. A similar method could be used to evaluate the perception of various configurations of electronic stability control (ESC) systems.

International audience; Some driving devices are designed to prevent road departures. One such device, motor priming (MP), provides small pulses to the steering wheel towards the lane centre, without correcting the trajectory itself. Compared with the other lane departure warning systems, its higher efficacy has been demonstrated; it is hypothesised that this relies on the action of haptic cues at the sensorimotor level (Navarro, J., Mars, F., and Hoc, J.M., 2007. Lateral control assistance for car drivers: a comparison of motor priming and warning systems. Human Factors, 49 (5), 950-960). The way in which corrective manoeuvres, primed by MP, can be influenced by processes that operate at higher levels of cognitive control, such as risk evaluation, is an issue. Results showed that MP improved all indicators of steering efficiency, starting with reaction times. Risk expectation and situation analysis did not influence reaction times but came into play soon after the corrective manoeuvre was initiated. Thus, although MP triggered the response at the sensorimotor level, higher levels of cognition (symbolic control) quickly modulated the execution of the corrective manoeuvre. Practitioner Summary: This paper showed that corrective manoeuvres following directional pulses on the steering wheel (motor priming) are modulated by risk expectation. The conclusion may be of interest for designers of haptics-based automation such as lane departure warning and lane keeping assistance systems.

This paper investigated drivers’ perception during situations of loss of adherence (LOA) in static and dynamic driving simulators. The intensity and duration of the LOA were manipulated. Results show that drivers were able to correctly discriminate the different conditions of LOA in both simulators. They also highlight the importance of nonvisual information, with steering wheel haptic cues predominating for the static simulator and both the steering wheel and motion platform predominating for the dynamic simulator. This study is a first step in developing an evaluation method for electronic stability control (ESC) handling in high-performance simulator experiments. [DOI: 10.1115/1.3622752]

International audience; Previous research has shown that a device called “motor priming” (MP) was more effective than other lane departure warning systems. MP prompts drivers to take action by means of small asymmetric oscillations of the steering wheel. The first objective of this experiment was to provide a deeper understanding of MP mechanisms through a series of comparisons with other haptic and auditory systems. The results suggest that much of the improvement in recovery manoeuvres observed with MP is due to the motor cue (proprioceptive preactivation of the gesture). Other factors, such as delivering the signal directly to the hands (stimulation of response effectors) or using the tactile modality rather than auditory warning, play a lesser role. This supports the hypothesis that MP devices directly intervene at the motor level, in contrast to more traditional warning systems, which only improve situation diagnosis. The second objective was to assess drivers' acceptance of the assistance devices. A dissociation between efficiency and acceptance of the devices was observed: drivers globally preferred auditory warning to MP. The combination of auditory warning and motor priming appeared to be a good compromise to achieve both effectiveness and acceptance. This experiment illustrates the relevance of simulator studies when dangerous situations are the main targets of the investigation.

International audience; OBJECTIVE: This paper's first objective is to determine whether motor priming assistance (consisting of directional steering wheel vibrations) can be of some benefit compared with more traditional auditory (lateralized sound) or vibratory (symmetric steering wheel oscillation) warning devices. We hypothesize that warning devices favor driving situation diagnosis, whereas motor priming can improve the initiation of action even further. Another objective is to assess the possible benefits of using multimodal information by combining auditory warning with simple steering wheel vibration or motor priming. BACKGROUND: Within the context of active safety devices, the experiment dealt with moderately intrusive driving assistance devices that intervene when a certain level of risk in terms of lane departure is reached. METHOD: An analysis of the steering behavior of 20 participants following episodes of visual occlusion was carried out. Five warning and motor priming devices were compared. RESULTS: All tested devices improved the drivers' steering performance, although their effects were modulated by the drivers' risk assessment. However, performance improvements were found to be greater with a motor priming device. No additional performance enhancement was observed when auditory warning was added to steering wheel vibration or motor priming devices. CONCLUSION: This study confirms the hypothesis that the direct intervention of motor priming at the action level is more effective than a simple warning, which intervenes upstream in situation diagnosis. Multimodal information did not seem to improve driver performance. APPLICATION: This study proposes a new kind of lateral control assistance, which acts at a sensorimotor level, in contrast with traditional warning devices.

Analyses of optic flow due to observer self-motion and analyses of the driver's gazing behavior during curve driving have suggested that the driver has a tendency to look at a location close to the tangent point on the inside edge of the road. Psychophysical experiments have further demonstrated that this visual strategy can be partly explained as an optimization of information pick-up. The main objective of the present study was to investigate, in an interactive simulation context, if this perceptual strategy might be used to define a visual aid for curve driving. In the framework of the French ARCOS project (Research action for secure driving; www.arcos2004.com), the authors used a mini-simulator developed by INRETS (MSIS-CIR group) in collaboration with FAROS company, with two main original characteristics: (1) during curve driving, the tangent point can be calculated and inserted in the visual scene in real-time and (2) a real-time eye-recording system (EYELINK,® SMI) allows the authors to evaluate the relationships between driving performance, gaze direction and the on-line presentation of the tangent point.

This study puts forward a classification of driver lateral control assistance devices based on distinctions among several cooperative activities between the driver and the assistance devices. The proposed classification is based on prior work by Hoc, Young and Blosseville and Young, Stanton and Harris, who put forward related theoretical frameworks on human–machine cooperation with automation. The particular application here to lateral control allows for a human-centred categorisation of existing and potential (i.e. near-future) driver assistance devices. Four human–machine cooperation levels based on drivers' activities have been adopted. All of the proposed categories are reviewed in three steps. First, each device category is functionally defined. Next, the impact of the devices on driving behaviour is presented. A third part sums up the effectiveness of each assistance category, particularly with regard to accident data. The general conclusion synthesises the main insights for each human–machine category proposed and highlights a number of design recommendations.