Method and device for determining the reaction time of a vehicle driver

Abstract

Method for determining the reaction time of a driver (2) of a vehicle (1), characterized by the steps: - Display of at least one visual stimulus (7); - Observing the direction of the driver's gaze (2) using a gaze detection device (3); - Determining the reaction time from the display of the visual stimulus (7), wherein the reaction time corresponds to a predetermined time interval if the driver's gaze direction (2) is not recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, or wherein the reaction time corresponds to a time interval in which the driver's gaze direction (2) is recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, wherein the duration of the predetermined time interval depends on the position of the displayed visual stimulus (7).

Description

[0001] The present invention relates to a method and a device for determining the reaction time of a vehicle driver. State of the art

[0002] To determine a driver's condition, for example, under the influence of fatigue or alcohol, reaction time and the size of the field of vision can be used as important criteria. Reaction time slows down under fatigue and alcohol influence. In addition, the size of the field of vision in which movements can still be perceived decreases. This is sometimes referred to as tunnel vision. In the future, methods that determine these parameters as automatically as possible will become increasingly important for assessing driver condition.

[0003] WO 93 / 16637 A1 discloses a device for detecting a person's reflex, in which a visual signal is randomly displayed at one of several predetermined and identifiable locations. When the person perceives the signal, they press a button. The time between the display and the button press is the reaction time.

[0004] WO 01 / 52722 A1 discloses a method for detecting the gaze direction of a user, in which a light beam is directed into the user's eye and its reflection is detected.

[0005] DE 10 2014 008 791 A1 discloses a driver assistance system for fatigue detection in which optical stimuli are transmitted to the driver and the resulting physiological reflexes are recorded and evaluated.

[0006] DE 20 2013 008 392 U1 discloses a device for estimating the attention of a driver, in which the driver's eye movement is detected in response to the switching of a display instrument.

[0007] DE 10 2005 058 678 A1 discloses a device for detecting driver fatigue, in which a visual stimulus is generated in the driver's field of vision and then moved. The driver's gaze information is recorded in the process.

[0008] DE 38 03 916 A1 discloses a method for determining the fitness to drive of a vehicle driver, in which the initial alignment of the eyes and the reaction speed are determined after optical stimulation of the driver.

[0009] No systems or procedures are currently known that can automatically detect the driver's condition. Disclosure of the invention

[0010] The inventive method for determining the reaction time of a vehicle driver basically comprises the following steps: - Display of at least one visual stimulus; - Observing the driver's gaze direction using a gaze detection device; - Determining the reaction time from the display of the visual stimulus, wherein the reaction time corresponds to a predetermined time period if the driver's gaze direction is not recognized as being in the direction of the visual stimulus within the predetermined time period, or wherein the reaction time corresponds to a time period in which the driver's gaze direction is recognized as being in the direction of the visual stimulus within the predetermined time period, wherein the duration of the predetermined time period depends on the position of the displayed visual stimulus.

[0011] According to the invention, it is possible to measure when the visual stimulus is perceived by the driver, or even whether it is perceived at all. From this, the time difference between the start of the visual stimulus's display and its recognition by the driver, as well as the driver's reaction time, can be determined. The system detects when the driver's gaze direction aligns with the display location of the visual stimulus known to the system. This can occur, for example, when the gaze direction vector intersects with the position of the visual stimulus or a predefined region around the position of the visual stimulus. If the driver fails to recognize the visual stimulus within a predetermined time period, the process, or at least the recognition of this visual stimulus, is aborted, and the reaction time is set to correspond to the predetermined time period.This procedure is very simple and very safe to perform.

[0012] Driving impairment can be detected if the reaction time falls within the predetermined time frame, and a vehicle safety function can be activated. If the driver fails to focus on or observe one or more visual stimuli within the predetermined time frame, driving impairment is detected for safety reasons. A vehicle safety function can then be activated, such as locking the ignition or issuing an audible warning to the driver. This increases road safety.

[0013] The driver's focus on the visual stimulus can be observed. This focus can be a more reliable criterion than simply recording the direction of gaze towards the visual stimulus, thus further increasing reliability. This focus can be determined, for example, by observing the pupils.

[0014] Displaying, observing, and determining the reaction time can all be performed during the calibration of the eye-tracking device. Advantageously, this allows calibration and reaction time determination to be carried out simultaneously. For calibration, a calibration sequence can be used, consisting of a series of visual stimuli, such as small circles, which appear randomly on the display unit at a position known to the system. A camera or other system captures the driver's eye area, and person-specific characteristics, such as corneal reflection, are evaluated to determine the direction of gaze. This means that only one system is needed to achieve the various objectives, saving costs and effort.The additional effort required to use an existing eye-tracking or eye-tracking system for measuring reaction time or the size of the consciously perceived field of vision is minimal. In this way, the determination or measurement of reaction time and / or the driver's field of vision is concealed. This prevents unintentional manipulation and distortion of the measurement results, for example, through momentary heightened concentration or assistance from other vehicle occupants.

[0015] The eye-tracking device can be part of an eye-tracking control device. Eye-tracking control devices are also becoming increasingly common in vehicles, so these systems can also be used advantageously in conjunction with the invention. Eye-tracking control systems can, under certain circumstances, provide more detailed and accurate results than eye-tracking devices alone.

[0016] In the inventive method, the duration of the predetermined time interval depends on the position of the displayed visual stimulus. For example, a visual stimulus can be detected more quickly in the central visual field than in a peripheral visual field. A corresponding adjustment of the predetermined time interval allows for a more precise method.

[0017] A driver's field of vision can be determined by analyzing the distribution of visual stimuli. The size of the field of vision in which the driver is still consciously aware of actions allows conclusions to be drawn about the driver's condition. If the driver is overtired, under the influence of alcohol, or has already developed tunnel vision, visual stimuli at the periphery of the field of vision may no longer be perceived at all, or the reaction time for these areas may be abnormally long. Alongside reaction time, the field of vision can be considered a second criterion for determining the driver's condition. This allows for a more plausible assessment of driving behavior and / or increased driving safety.

[0018] According to the invention, a device for determining the reaction time of a vehicle driver is provided, comprising a display device for displaying at least one visual stimulus, a camera for observing the driver's gaze direction, and a computing device configured for controlling the display device and for determining the reaction time starting with the display of the visual stimulus, wherein the reaction time corresponds to a predetermined time interval if the driver's gaze direction is not recognized as being in the direction of the visual stimulus within the predetermined time interval, or wherein the reaction time corresponds to a time interval in which the driver's gaze direction is recognized as being in the direction of the visual stimulus within the predetermined time interval, wherein the duration of the predetermined time interval depends on the position of the displayed visual stimulus.This can be the case, for example, when the gaze direction vector intersects with the position of the visual stimulus or a predefined region around the position of the visual stimulus. The same advantages and modifications apply as described previously.

[0019] The display device can be positioned in the area of ​​the vehicle's windshield. There, the visual stimuli can be directly perceived by the driver and correspond to the actual field of vision required for driving.

[0020] The display device can include at least one LED and / or a laser for displaying the visual stimulus. The LED or laser can be part of an existing system such as a head-up display (HUD), a display such as a display of the central driver information system, or a visualization of the stimuli in the instrument cluster. These could also be directly controlled by the processing unit 5 for visualization. Drawings

[0021] Exemplary embodiments of the invention are explained in more detail with reference to the drawings and the following description. The drawings show: Fig. 1. A schematic representation of a motor vehicle with a device for determining a driver's reaction time; and Fig. 2. A flowchart of a procedure for determining the reaction time of a vehicle driver. Embodiments of the invention

[0022] Fig. Figure 1 shows a schematic representation of the front section of a vehicle 1, which is driven or is to be driven by a driver 2. The term "vehicle" here includes land-based vehicles, such as cars, trucks, buses, motorcycles, and so on; watercraft, such as ships or ferries; and aircraft, such as airplanes. Rail vehicles, such as locomotives or trams, are also included.

[0023] A gaze detection device 3, which may also be part of a gaze control device, comprises at least one camera 4 for observing the driver 2, in particular the driver's face, eyes, or gaze direction. The camera is connected to a processing device 5, which evaluates the images or signals from the camera 4. A display device 6 for at least one visual stimulus 7 is provided for calibrating the gaze detection device 3. The visual stimulus is, for example, as shown here, a circle displayed on a windshield 8 of the vehicle 1.

[0024] The eye-tracking device 3 is part of a device 9 for determining the reaction time of the driver 2. The described elements of the eye-tracking device 3, namely the camera 4, the computing device 5, and the display device 6, can also be part of the device 9 for determining the reaction time. For the purpose of determining the reaction time, the computing device 5 is configured to determine or measure the time between the display of the visual stimulus 7 and the driver 2's detection of the visual stimulus 7. This duration corresponds to the driver 2's reaction time.

[0025] Furthermore, the computing device 5 is configured to detect a field of vision 10 or a visual area or angular range of the field of vision 10 of the driver 2. For this purpose, various optical or visual stimuli 7 are distributed along the windshield 8 in order to determine the boundaries of the field of vision 10 of the driver 2. Fig. Figure 1 shows a so-called tunnel vision, which is characterized by a small angle a and allows the conclusion that the driver 2 is under the influence of alcohol or is tired.

[0026] Based on Fig.Section 2 now explains in more detail the procedure for determining the reaction time of the driver 2. In a first step 100, a visual stimulus 7 or several visual stimuli 7 are displayed on the windshield 8 within the driver's field of vision. The location of the display of the visual stimulus 7, that is, its position on the windshield 8 in terms of height and lateral orientation, i.e., perpendicular to the direction of travel of the vehicle 1, is controlled by the computing device 5. The display of the visual stimuli 7 to the driver 2 is random. However, the computing device 5 can display the visual stimuli 7 according to a program, for example, to determine the driver's field of vision 10.

[0027] In a second step, the direction of the driver's gaze is observed or determined. For example, the driver's eye movements are tracked using one or more cameras, thus determining the direction of the driver's gaze.

[0028] In a further step 120, it is determined whether the driver's gaze direction 2 is directed towards the displayed optical stimulus 7, or whether the gaze direction vector intersects with the position of the visual stimulus or a predefined region around the position of the visual stimulus. Alternatively or additionally, it can be determined whether the driver 2 is focusing on the visual stimulus 7.

[0029] If this is the case, in a further step 130 the time difference between the start of the display and the detection by the driver 2 is determined or measured. This time difference corresponds to the reaction time of the driver 2. The reaction time begins when the display device 6, upon activation of the computing device 5, displays a visual stimulus 7, for example on the windshield 8. The time period ends when the camera 4 or the computing device 5 detects that the driver 2 has detected or recognized the visual stimuli 7.

[0030] In a further step 140, it is determined whether the driver's perception, or in other words, whether the driver's reaction time 2 falls within a predetermined time period. This time period or time window terminates step 130, the process of the driver's perception of the visual stimulus 7 and the determination of the reaction time. This serves to exclude excessively long reaction times, during which the driver is unfit to drive or only partially fit to drive.

[0031] This predetermined time interval can be in the range of seconds or fractions of seconds. If the predetermined time interval serves to determine the driver's unfitness to drive, its length or duration is determined by criteria for unfitness or fitness to drive. The length of the predetermined time interval can be varied by the computing device 5; for example, each position of the visual stimulus can be assigned its own predetermined time interval. Alternatively, it is possible for certain zones, such as a central area of ​​the windshield 8 and side areas of the windshield 8, to be assigned different predetermined time intervals. Finally, it can be provided that the time windows are adjusted to the calibration process, since certain timing sequences must be taken into account for calibration.

[0032] If a normal reaction time is detected in step 140, meaning that the reaction time is below or within the predetermined time period, the driver 2 can start the vehicle 1 and begin the journey. Preferably, the procedure described here takes place as part of a calibration of the eye-tracking device 3 before the vehicle 1 is started.

[0033] If the predetermined time interval is exceeded, a safety function of the vehicle 1 is activated in a further step 150. This might involve, for example, locking the ignition and / or issuing a warning to the driver 2. This step 150 is also executed if the visual stimulus 7 is not detected or not detected correctly by the driver 2 in step 120. Steps 120 and 140 can be combined so that the process branches to step 150 as early as step 120 if the predetermined time interval is exceeded.

Claims

[1] Method for determining the reaction time of a driver (2) of a vehicle (1), characterized by the steps: - Display of at least one visual stimulus (7); - Observing the direction of the driver's gaze (2) using a gaze detection device (3); - Determining the reaction time from the display of the visual stimulus (7), wherein the reaction time corresponds to a predetermined time interval if the driver's gaze direction (2) is not recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, or wherein the reaction time corresponds to a time interval in which the driver's gaze direction (2) is recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, wherein the duration of the predetermined time interval depends on the position of the displayed visual stimulus (7). [2] Method according to claim 1, wherein unfitness to drive is detected when the reaction time corresponds to the predetermined time interval and a safety function of the vehicle (1) is activated. [3] Method according to claim 1 or 2, wherein a focusing of the vehicle driver (2) on the visual stimulus (7) is observed. [4] Method according to any one of claims 1 to 3, wherein the display, observation and determination is carried out during a calibration of the eye-tracking device (3). [5] Method according to any one of claims 1 to 4, wherein the gaze detection device (3) is part of a gaze control device. [6] Method according to one of claims 1 to 5, wherein a visual field (10) of the driver (2) is determined via a distribution of the visual stimuli (7). [7] Device for determining the reaction time of a driver (2) of a vehicle (1), characterized bya display device (6) for displaying at least one visual stimulus (7), a camera (4) for observing the direction of gaze of the driver (2), and a computing device (5) configured for controlling the display device (6) and for determining the reaction time starting with the display of the visual stimulus (7), wherein the reaction time corresponds to a predetermined time interval if the direction of gaze of the driver (2) is not recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, or wherein the reaction time corresponds to a time interval in which the direction of gaze of the driver (2) is recognized as being in the direction of the visual stimulus (7) within the predetermined time interval, wherein the duration of the predetermined time interval depends on the position of the displayed visual stimulus (7). [8] Device according to claim 7, wherein the display device is arranged in the area of ​​a windshield (8) of the vehicle (1). [9] Device according to claim 7 or 8, wherein the display device (6) has at least one LED and / or a laser for displaying the visual stimulus (7).

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