Patent Description:
It is known to detect a driver's level of fatigue by tracking a lane-keeping-performance that determines how well a driver maintains a lane-position. Excessive movement within a lane and/or excessive lane-departures may indicate an unsafe level of driver-fatigue and may lead to an activation of an alert-device that alerts the driver to their lowered level of responsiveness.

<CIT> discloses a drive assist system of a vehicle for preventing a lane moving-out in which a warning is raised when the vehicle comes close to the lane marker of a road. The drive assist system has a pair of cameras in order to take pictures of the scenery at the front of the vehicle. A controller extracts necessary information from the images captured by the cameras. If it is judged that the vehicle is moving out from the lane, a driver's attention can be called by raising an alarm.

It is an object of the invention to provide an improved method of operating an alert device of a vehicle that reduces rates of a false driver-fatigue warning. Furthermore, it is an object of the invention to provide an improved system that reduces rates of a false driver-fatigue warning.

The object is solved by a method according to claim <NUM> and a system according to claim <NUM>. Advantages embodiments are defined in the dependent claims.

In accordance with one embodiment, a not claimed driver-fatigue warning system is provided. The driver-fatigue warning system suitable for use in an automated vehicle includes a camera, an alert-device, and a controller. The camera renders an image of a lane-marking and of an object proximate to a host-vehicle. The alert-device is operable to alert an operator of the host-vehicle of driver-fatigue. The controller is in communication with the camera and the alert-device. The controller determines a vehicle-offset of the host-vehicle relative to the lane-marking based on the image. The controller determines an offset-position of the object relative to the lane-marking based on the image. The controller determines that a lane-departure has occurred when the vehicle-offset is less than a deviation-threshold. The controller does not count occurrences of lane-departures when the offset-position is less than an offset-threshold, and activates the alert-device when the count of the occurrences of lane-departures exceeds a crossing-threshold indicative of driver-fatigue.

The not claimed system may further include a ranging-sensor in communication with the controller, said ranging-sensor detects a range, and azimuth-angle of the object, wherein the controller may further determine the offset-position based on the range and the azimuth-angle. The ranging-sensor may be a radar, a lidar or an ultrasonic-transducer. The controller may further determine that the object is in an adjacent-lane and counts the lane-departure when the lane-departure is into the adjacent-lane.

In another embodiment, a method of operating an alert device of a vehicle is provided. The method includes the steps of I) capturing, by a camera, an image, II) determining a vehicle-offset, III) determining an object offset, IV) determining occurrences of lane-departure, V) incrementing a count, VI) refraining from incrementing the count, VII) determining that the count exceeds a crossing-threshold, and VIII) activating an alert-device. The step of capturing an image includes capturing, with a camera, an image of a lane-marking and of an object proximate to a host-vehicle. The step of alerting an operator includes alerting, with an alert-device, an operator of the host-vehicle of driver-fatigue. The step of determining the vehicle-offset includes determining with a controller in communication with the camera and the alert-device, the vehicle-offset of the host-vehicle relative to the lane-marking based on the image. The step of determining the object offset includes determining the object offset of the object relative to the lane-marking based on the image. The step of determining occurrences of lane-departure includes determining that the lane-departure has occurred when the vehicle-offset is less than a deviation-threshold, and not counting occurrences of lane-departures when the object offset is less than an offset-threshold and a greater clearance between the vehicle and the object is provided by the lane departure. The step of activating the alert-device includes activating the alert-device when the count of the occurrences of lane-departures exceeds a crossing-threshold indicative of driver-fatigue.

The system may further include a ranging-sensor in communication with the controller, further including the steps of detecting, with the ranging-sensor, a range, and azimuth-angle of the object, and determining, with the controller, the offset-position based on the range and the azimuth-angle. The method may further include the steps of determining, with the controller, that the object is in an adjacent-lane and counting the lane-departure when the lane-departure is into the adjacent-lane.

In yet another embodiment, an automated vehicular warning system is provided. The automated vehicular warning system may include a camera, an alert-device, and a controller in communication with the camera and the alert-device. The controller counts a lane-departure of a host-vehicle when a host-vehicle-offset relative to a lane-marking is less than a threshold. The controller does not count the lane-departure when an object in a roadway urges an operator of the host-vehicle to perform the lane-departure. The controller activates the alert-device when the count of the lane-departures exceeds a departure-threshold.

Further features and advantages will appear more clearly on a reading of the following detailed description of the preferred embodiment, which is given by way of non-limiting example only and with reference to the accompanying drawings.

A typical driver-fatigue system detects whether an operator of a host-vehicle is drowsy or fatigued by measuring a lane-keeping-performance. The typical lane-keeping-performance algorithm estimates an operator's ability to drive the host-vehicle along a centerline of a travel-lane by detecting certain sequences of events, and/or a lack of steering-activity. Events that are indicative of driver-fatigue include, but are not limited to, a variation in a lateral-offset of the host-vehicle from the centerline, and/or no steering-activity while the host-vehicle drifts away from the centerline followed by a sudden steering-correction back to the centerline (a. It is known in the art that a significant increase in a number of lane-crossings, without the use of signaling, may be an indicator of driver-fatigue.

While the typical lane-keeping-performance algorithm may accurately estimate the driver-fatigue under ideal traffic conditions, situations exist where the operator may intentionally perform a lane-departure to avoid an object in an adjacent-lane or on a shoulder of a roadway (e.g. an oversize-load being transported or an other-vehicle stopped on the shoulder), or to avoid an object in the travel-lane (e.g. a pot-hole or debris). While these lane-departures may be associated with cautious and/or courteous driving maneuvers, they may be counted by the typical lane-keeping-performance algorithm as an indication of driver-fatigue, and may lead to a false driver-fatigue warning. As will be described in more detail below, the system described herein is an improvement over prior driver-fatigue warning systems because the system reduces the rates of the false driver-fatigue warning by determining when to count the lane-departure, which may help to reduce occurrences of operators intentionally deactivating the driver-fatigue warning system.

<FIG> illustrates a non-limiting example of a driver-fatigue warning system <NUM>, hereafter referred to as the system <NUM>, suitable for use in an automated vehicle <NUM>, hereafter referred to as a host-vehicle <NUM>. As used herein, the term `automated vehicle' is not meant to suggest that fully automated or autonomous operation of the host-vehicle <NUM> is required. It is contemplated that the teachings presented herein are applicable to instances where the host-vehicle <NUM> is entirely manually operated by a human and the automation is merely providing emergency braking to the human. The system <NUM> includes a camera <NUM> that renders an image <NUM> of a lane-marking <NUM> of a roadway <NUM> and of an object <NUM> proximate to the host-vehicle <NUM>. Examples of the camera <NUM> suitable for use on the host-vehicle <NUM> are commercially available as will be recognized by those in the art, one such being the APTINA MT9V023 from Micron Technology, Inc. of Boise, Idaho, USA. The camera <NUM> may be mounted on the front of the host-vehicle <NUM>, or mounted in the interior of the host-vehicle <NUM> at a location suitable for the camera <NUM> to view the area around the host-vehicle <NUM> through the windshield of the host-vehicle <NUM>. The camera <NUM> is preferably a video-type camera <NUM> or camera <NUM> that can capture images <NUM> of the roadway <NUM> and surrounding area at a sufficient frame-rate, of ten frames per second, for example. A travel-lane <NUM> may be defined by the lane-markings <NUM>, or may be defined by edges of pavement if no lane-markings <NUM> are detected. The image <NUM> includes, but is not limited to, the lane-marking <NUM> on a left-side and on a right-side of the travel-lane <NUM> of the roadway <NUM>. The image <NUM> may also include the lane-marking <NUM> in an adjacent-lane <NUM>. The lane-marking <NUM> may include a solid-line, a dashed-line, or any combination thereof.

The system <NUM> also includes an alert-device <NUM> operable to alert an operator <NUM> of the host-vehicle <NUM> of driver-fatigue. The alert-device <NUM> may be an indicator viewable by the operator <NUM> that is illuminated to indicate an instance of driver-fatigue, and/or an audible alarm, and/or a vibratory alarm that is activated to indicate the same.

The system <NUM> also includes a controller <NUM> in communication with the camera <NUM> and the alert-device <NUM>. The controller <NUM> may include a processor (not shown) such as a microprocessor or other control circuitry such as analog and/or digital control circuitry including an application specific integrated circuit (ASIC) for processing data as should be evident to those in the art. The controller <NUM> may include a memory (not specifically shown), including non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM) for storing one or more routines, thresholds, and captured data. The one or more routines may be executed by the processor to perform steps for determining if a detected instance of driver-fatigue exists based on signals received by the controller <NUM> from the camera <NUM> as described herein.

The controller <NUM> may receive the image <NUM>, via a video-signal (not shown), and may determine both a lane-width (not specifically shown) and a centerline <NUM> of the travel-lane <NUM> based on the lane-marking <NUM>. That is, the image <NUM> detected or captured by the camera <NUM> is processed by the controller <NUM> using known techniques for image-analysis to determine where along the roadway <NUM> the host-vehicle <NUM> should be operated or be steered. Vision processing technologies, such as the EyeQ® platform from Mobileye Vision Technologies, Ltd. of Jerusalem, Israel, or other suitable devices may be used. By way of example and not limitation, the centerline <NUM> is preferably in the middle of the travel-lane <NUM> traveled by the host-vehicle <NUM>.

<FIG> illustrates a traffic scenario where the host-vehicle <NUM> is approaching the object <NUM> (i.e. an oversize-load) that is traveling in the adjacent-lane <NUM>. The operator <NUM> of the host-vehicle <NUM> makes an intentional lane-departure <NUM>, as is indicated by a perimeter of the host-vehicle <NUM> overlaying the lane-marking <NUM> on the left-side of the travel-lane <NUM>, to provide greater clearance between the host-vehicle <NUM> and the object <NUM>. The controller <NUM> determines a vehicle-offset <NUM> of the host-vehicle <NUM> relative to the lane-marking <NUM> based on the image <NUM> received from the camera <NUM>. The vehicle-offset <NUM> is a measure of a distance from both a left-side and a right-side of the host-vehicle <NUM> to the lane-marking <NUM>. The controller <NUM> determines that the lane-departure <NUM> has occurred when the vehicle-offset <NUM> is less than a deviation-threshold <NUM>. The deviation-threshold <NUM> as used herein is defined as a minimum allowable distance from the left-side and/or the right-side of the host-vehicle <NUM> to the lane-marking <NUM>. The deviation-threshold <NUM> may be user-defined and may be any distance needed to meet the requirements of the host-vehicle <NUM>, and may be in a range from between zero meters (<NUM> meters) to <NUM> meters. The deviation-threshold <NUM> may vary based on a width of the host-vehicle <NUM> and/or may vary based on the width of the travel-lane <NUM>. An occurrence of the lane-departure <NUM> may be counted <NUM> by the controller <NUM> and may be stored in the memory for estimating the operator's <NUM> lane-keeping-performance.

As illustrated in <FIG>, the controller <NUM> also determines an offset-position <NUM> of the object <NUM> relative to the lane-marking <NUM> based on the image <NUM>. The offset-position <NUM> is defined as the distance from either the left-side or the right-side of the object <NUM> to the lane-marking <NUM> of the travel-lane <NUM> traveled by the host-vehicle <NUM>. The controller <NUM> also determines an offset-threshold <NUM> defined as the minimum allowable distance from the left-side and/or the right-side of the object <NUM> to the lane-marking <NUM> of the travel-lane <NUM> traveled by the host-vehicle <NUM> (shown on the left-side of the object <NUM> in <FIG> for illustration purposes only). The offset-threshold <NUM> may be user-defined and may be any distance needed to meet the requirements of the host-vehicle <NUM>, and may be in the range from between <NUM> meters to <NUM> meters. The offset-threshold <NUM> may vary based on a width of the object <NUM> and/or may vary based on the width of the travel-lane <NUM>, and/or may vary based on the width of the host-vehicle <NUM>.

The controller <NUM> does not count occurrences of the lane-departures <NUM> of the host-vehicle <NUM> when the offset-position <NUM> is less than the offset-threshold <NUM> as illustrated in <FIG>. By not counting <NUM> the occurrences of the lane-departures <NUM> under the aforementioned conditions, the system <NUM> does not penalize the operator <NUM> of the host-vehicle <NUM> when the operator <NUM> makes an intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM>.

<FIG> illustrates another traffic scenario where the operator <NUM> of the host-vehicle <NUM> makes the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> (e.g. a pot-hole and/or debris) located in the travel-lane <NUM> traveled by the host-vehicle <NUM> that is perceived as a hazard by the operator <NUM>. As illustrated in <FIG>, the operator <NUM> makes the lane-departure <NUM> to the left-side of the travel-lane <NUM>. The controller <NUM> does not count the occurrence of the lane-departure <NUM> when the offset-position <NUM> (illustrated as a negative value of distance from the lane-marking <NUM>) is less than the offset-threshold <NUM> as illustrated in <FIG>. The location of the detected object <NUM> may urge the operator <NUM> to make the intentional lane-departure <NUM> to either-side of the object <NUM> and will not be counted <NUM> by the controller <NUM>.

<FIG> illustrates yet another traffic scenario where the operator <NUM> of the host-vehicle <NUM> makes the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> (e.g. construction pylons) located on the shoulder of the travel-lane <NUM> that are perceived as the hazard by the operator <NUM>. As illustrated in <FIG>, the operator <NUM> is making the lane-departure <NUM> to the left-side of the travel-lane <NUM>. The controller <NUM> does not count the occurrence of the lane-departure <NUM> when the offset-position <NUM> is less than the offset-threshold <NUM>.

<FIG> illustrates yet another traffic scenario where the controller <NUM> further determines that the object <NUM> (e.g. the oversize-load) is in the adjacent-lane <NUM>, and determines that the lane-departure <NUM> also occurs into the adjacent-lane <NUM>. In contrast to the traffic scenario illustrated in <FIG>, the controller <NUM> counts <NUM> the lane-departure <NUM> illustrated in <FIG> because the host-vehicle <NUM> moves closer to the object <NUM> without signaling the maneuver, which may be indicative of driver-fatigue.

The controller <NUM> activates the alert-device <NUM> when the count <NUM> of the occurrences of lane-departures <NUM> exceeds a crossing-threshold <NUM> (see <FIG>) indicative of driver-fatigue. The crossing-threshold <NUM> may be any number of occurrences of lane-departures <NUM> within a defined time-period, and is preferably in the range from between <NUM> to <NUM> lane-departures <NUM> within the time-period of two minutes.

Returning to <FIG>, the system <NUM> may further include a ranging-sensor <NUM> in communication with the controller <NUM>. The ranging-sensor <NUM> may detect a range <NUM>, and an azimuth-angle <NUM> of the object <NUM> relative to a host-vehicle-longitudinal-axis (not shown). The ranging-sensor <NUM> may be a radar <NUM> such as the radar-sensor from Delphi Inc. of Troy, Michigan, USA and marketed as an Electronically Scanning Radar (ESR) or a Rear-Side-Detection-System (RSDS), or Short-Range-Radar (SRR) or the ranging-sensor <NUM> may be a lidar <NUM>, or the ranging-sensor <NUM> may be an ultrasonic-transducer <NUM> such as the TIDA-<NUM> from Texas Instruments of Dallas, Texas, USA. The controller <NUM> may further determine the offset-position <NUM> of the object <NUM> based on the range <NUM> and the azimuth-angle <NUM>, as will be understood by those in the art.

<FIG> illustrates a non-limiting example of a method <NUM> of operating a driver-fatigue warning system <NUM> illustrated in <FIG>, hereafter referred to as the system <NUM>, suitable for use in an automated vehicle, hereafter referred to as a host-vehicle <NUM>. As used herein, the term `automated vehicle' is not meant to suggest that fully automated or autonomous operation of the host-vehicle <NUM> is required. It is contemplated that the teachings presented herein are applicable to instances where the host-vehicle <NUM> is entirely manually operated by a human and the automation is merely providing emergency braking to the human.

Step <NUM>, CAPTURE IMAGE, may include the step of capturing, with a camera <NUM>, an image <NUM> of a lane-marking <NUM> of a roadway <NUM> and of an object <NUM> proximate to the host-vehicle <NUM>. Examples of the camera <NUM> suitable for use on the host-vehicle <NUM> are commercially available as will be recognized by those in the art, one such being the APTINA MT9V023 from Micron Technology, Inc. of Boise, Idaho, USA. The camera <NUM> may be mounted on the front of the host-vehicle <NUM>, or mounted in the interior of the host-vehicle <NUM> at a location suitable for the camera <NUM> to view the area around the host-vehicle <NUM> through the windshield of the host-vehicle <NUM>. The camera <NUM> is preferably a video-type camera <NUM> or camera <NUM> that can capture images <NUM> of the roadway <NUM> and surrounding area at a sufficient frame-rate, of ten frames per second, for example. A travel-lane <NUM> may be defined by the lane-markings <NUM>, or may be defined by edges of pavement if no lane-markings <NUM> are detected. The image <NUM> may include, but is not limited to, the lane-marking <NUM> on a left-side and on a right-side of the travel-lane <NUM> of the roadway <NUM>. The image <NUM> may also include the lane-marking <NUM> in an adjacent-lane <NUM>. The lane-marking <NUM> may include a solid-line, a dashed-line, or any combination thereof.

Step <NUM>, ALERT OPERATOR, may include the step of alerting, with an alert-device <NUM>, an operator <NUM> of the host-vehicle <NUM> of driver-fatigue. The alert-device <NUM> may be an indicator viewable by the operator <NUM> that is illuminated to indicate an instance of driver-fatigue, and/or an audible alarm, and/or a vibratory alarm that is activated to indicate the same.

Step <NUM>, DETERMINE VEHICLE-OFFSET, may include determining, with a controller <NUM> in communication with the camera <NUM> and the alert-device <NUM>, a vehicle-offset <NUM> of the host-vehicle <NUM> relative to the lane-marking <NUM> based on the image <NUM>. The controller <NUM> may include a processor (not shown) such as a microprocessor or other control circuitry such as analog and/or digital control circuitry including an application specific integrated circuit (ASIC) for processing data as should be evident to those in the art. The controller <NUM> may include a memory (not specifically shown), including non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM) for storing one or more routines, thresholds, and captured data. The one or more routines may be executed by the processor to perform steps for determining if a detected instance of driver-fatigue exists based on signals received by the controller <NUM> from the camera <NUM> as described herein.

<FIG> illustrates a traffic scenario where the host-vehicle <NUM> is approaching the object <NUM> (i.e. an oversize-load) that is traveling in the adjacent-lane <NUM>. The operator <NUM> of the host-vehicle <NUM> makes an intentional lane-departure <NUM>, as is indicated by a perimeter of the host-vehicle <NUM> overlaying the lane-marking <NUM> on the left-side of the travel-lane <NUM>, to provide greater clearance between the host-vehicle <NUM> and the object <NUM>. The controller <NUM> determines the vehicle-offset <NUM> of the host-vehicle <NUM> relative to the lane-marking <NUM> based on the image <NUM> received from the camera <NUM>. The vehicle-offset <NUM> is a measure of a distance from both a left-side and a right-side (not specifically shown) of the host-vehicle <NUM> to the lane-marking <NUM>.

Step <NUM>, DETERMINE LANE-DEPARTURE, may include the step of determining, with the controller <NUM>, that the lane-departure <NUM> has occurred when the vehicle-offset <NUM> is less than a deviation-threshold <NUM>. The deviation-threshold <NUM> as used herein is defined as a minimum allowable distance from the left-side and/or the right-side of the host-vehicle <NUM> to the lane-marking <NUM>. The deviation-threshold <NUM> may be user-defined and may be any distance needed to meet the requirements of the host-vehicle <NUM>, and may be in a range from between zero meters (<NUM> meters) to <NUM> meters. The deviation-threshold <NUM> may vary based on a width of the host-vehicle <NUM> and/or may vary based on the width of the travel-lane <NUM>. An occurrence of the lane-departure <NUM> may be counted <NUM> by the controller <NUM> and may be stored in the memory for estimating the operator's <NUM> lane-keeping-performance.

Step <NUM>, DETERMINE OFFSET-POSITION, may include the step of determining, with the controller <NUM>, an offset-position <NUM> of the object <NUM> relative to the lane-marking <NUM> based on the image <NUM>. The offset-position <NUM> is defined as the distance from either the left-side or the right-side of the object <NUM> to the lane-marking <NUM> of the travel-lane <NUM> traveled by the host-vehicle <NUM>. The controller also determines an offset-threshold <NUM> defined as the minimum allowable distance from the left-side and/or the right-side of the object <NUM> to the lane-marking <NUM> of the travel-lane <NUM> traveled by the host-vehicle <NUM> (shown only on the left-side of the object <NUM> in <FIG> for illustration purposes only). The offset-threshold <NUM> may be user-defined and may be any distance needed to meet the requirements of the host-vehicle <NUM>, and may be in the range from between <NUM> meters to <NUM> meters. The offset-threshold <NUM> may vary based on a width of the object <NUM> and/or may vary based on the width of the travel-lane <NUM>, and/or may vary based on the width of the host-vehicle <NUM>.

<FIG> illustrates yet another traffic scenario where the operator <NUM> of the host-vehicle <NUM> makes the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> (e.g. construction pylons) located on the shoulder of the travel-lane <NUM> that are perceived as the hazard by the operator <NUM>. As illustrated in <FIG>, the operator.

<NUM> is making the lane-departure <NUM> to the left-side of the travel-lane <NUM>. The controller <NUM> does not count the occurrence of the lane-departure <NUM> when the offset-position <NUM> is less than the offset-threshold <NUM>.

Step <NUM>, ACTIVATE ALERT-DEVICE, may include the step of activating, with the controller <NUM>, the alert-device <NUM> when the count <NUM> of the occurrences of lane-departures <NUM> exceeds a crossing-threshold <NUM> (see <FIG>) indicative of driver-fatigue. The crossing-threshold <NUM> may be any number of occurrences of lane-departures <NUM> within a defined time-period, and is preferably in the range from between <NUM> to <NUM> lane-departures <NUM> within the time-period of two minutes.

Returning to <FIG>, the system <NUM> may further include a ranging-sensor <NUM> in communication with the controller <NUM>. The ranging-sensor <NUM> may detect a range <NUM>, and an azimuth-angle <NUM> of the object <NUM> relative to a host-vehicle-longitudinal-axis (not shown). The ranging-sensor <NUM> may be a radar <NUM> such as the radar-sensor from Delphi Inc. of Troy, Michigan, USA and marketed as an Electronically Scanning Radar (ESR) or a Rear-Side-Detection-System (RSDS), or Short-Range-Radar (SRR), or the ranging-sensor <NUM> may be a lidar <NUM>, or the ranging-sensor <NUM> may be an ultrasonic-transducer <NUM> such as the TIDA-<NUM> from Texas Instruments of Dallas, Texas, USA. The controller <NUM> may further determine the offset-position <NUM> of the object <NUM> based on the range <NUM> and the azimuth-angle <NUM>, as will be understood by those in the art.

<FIG> is a non-limiting example of yet another embodiment of an automated vehicular warning system <NUM>, hereafter referred to as the system <NUM>, suitable for use on an automated vehicle <NUM>, hereafter referred to as a host-vehicle <NUM>. As used herein, the term `automated vehicle' is not meant to suggest that fully automated or autonomous operation of the host-vehicle <NUM> is required. It is contemplated that the teachings presented herein are applicable to instances where the host-vehicle <NUM> is entirely manually operated by a human and the automation is merely providing emergency braking to the human. The system <NUM> includes a camera <NUM> that renders an image <NUM> of a lane-marking <NUM> of a roadway <NUM> and of an object <NUM> proximate to the host-vehicle <NUM>. Examples of the camera <NUM> suitable for use on the host-vehicle <NUM> are commercially available as will be recognized by those in the art, one such being the APTINA MT9V023 from Micron Technology, Inc. of Boise, Idaho, USA. The camera <NUM> may be mounted on the front of the host-vehicle <NUM>, or mounted in the interior of the host-vehicle <NUM> at a location suitable for the camera <NUM> to view the area around the host-vehicle <NUM> through the windshield of the host-vehicle <NUM>. The camera <NUM> is preferably a video-type camera <NUM> or camera <NUM> that can capture images <NUM> of the roadway <NUM> and surrounding area at a sufficient frame-rate, of ten frames per second, for example. A travel-lane <NUM> may be defined by the lane-markings <NUM>, or may be defined by edges of pavement if no lane-markings <NUM> are detected. The image <NUM> may include, but is not limited to, the lane-marking <NUM> on a left-side and on a right-side of the travel-lane <NUM> of the roadway <NUM>. The image <NUM> may also include the lane-marking <NUM> in an adjacent-lane <NUM>. The lane-marking <NUM> may include a solid-line, a dashed-line, or any combination thereof.

<FIG> illustrates a traffic scenario where the host-vehicle <NUM> is approaching the object <NUM> (i.e. an oversize-load) that is traveling in the adjacent-lane <NUM>. The operator <NUM> of the host-vehicle <NUM> makes an intentional lane-departure <NUM>, as is indicated by a perimeter of the host-vehicle <NUM> overlaying the lane-marking <NUM> on the left-side of the travel-lane <NUM>, to provide greater clearance between the host-vehicle <NUM> and the object <NUM>. The controller <NUM> determines a host-vehicle-offset <NUM> of the host-vehicle <NUM> relative to the lane-marking <NUM> based on the image <NUM> received from the camera <NUM>. The host-vehicle-offset <NUM> is a measure of a distance (not specifically shown) from both a left-side and a right-side (not specifically shown) of the host-vehicle <NUM> to the lane-marking <NUM>. The controller <NUM> determines that the lane-departure <NUM> has occurred when the host-vehicle-offset <NUM> is less than a threshold <NUM>. The threshold <NUM> as used herein is defined as a minimum allowable distance from the left-side and/or the right-side of the host-vehicle <NUM> to the lane-marking <NUM>. The threshold <NUM> may be user-defined and may be any distance needed to meet the requirements of the host-vehicle <NUM>, and may be in a range from between zero meters (<NUM> meters) to <NUM> meters. The threshold <NUM> may vary based on a width of the host-vehicle <NUM> and/or may vary based on the width of the travel-lane <NUM>. An occurrence of the lane-departure <NUM> may be counted <NUM> by the controller <NUM> and may be stored in the memory for estimating the operator's <NUM> lane-keeping-performance.

The controller <NUM> does not count <NUM> occurrences of the lane-departures <NUM> of the host-vehicle <NUM> when the offset-position <NUM> is less than the offset-threshold <NUM> as illustrated in <FIG> By not counting <NUM> the occurrences of the lane-departures <NUM> under the aforementioned conditions, the system <NUM> does not penalize the operator <NUM> of the host-vehicle <NUM> when the operator <NUM> makes an intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM>.

<FIG> illustrates another traffic scenario where the operator <NUM> of the host-vehicle <NUM> makes the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> (e.g. a pot-hole and/or debris) located in the travel-lane <NUM> traveled by the host-vehicle <NUM> that is perceived as a hazard by the operator <NUM>. As illustrated in <FIG>, the operator <NUM> is making the lane-departure <NUM> to the left-side of the travel-lane <NUM>. The controller <NUM> does not count <NUM> the occurrence of the lane-departure <NUM> when the offset-position <NUM> (illustrated as a negative value of distance from the lane-marking <NUM>) is less than the offset-threshold <NUM> as illustrated in <FIG>. The location of the detected object <NUM> may urge the operator <NUM> to make the intentional lane-departure <NUM> to either-side of the object <NUM> and will not be counted <NUM> by the controller <NUM>.

<FIG> illustrates yet another traffic scenario where the operator <NUM> of the host-vehicle <NUM> makes the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> (e.g. construction pylons) located on the shoulder of the travel-lane <NUM> that are perceived as the hazard by the operator <NUM>. As illustrated in <FIG>, the operator <NUM> is making the lane-departure <NUM> to the left-side of the travel-lane <NUM>. The controller <NUM> does not count <NUM> the occurrence of the lane-departure <NUM> when the offset-position <NUM> is less than the offset-threshold <NUM>.

The controller <NUM> activates the alert-device <NUM> when the count <NUM> of the occurrences of lane-departures <NUM> exceeds a departure-threshold <NUM> (see <FIG>) indicative of driver-fatigue. The departure-threshold <NUM> may be any number of occurrences of lane-departures <NUM> within a defined time-period, and is preferably in the range from between <NUM> to <NUM> lane-departures <NUM> within the time-period of two minutes.

<FIG> illustrates a non-limiting example of the driver-fatigue algorithm that may be stored in the memory of the controller <NUM>. The driver-fatigue algorithm may include logic that includes making decisions based on sensor input, lane-departure-warnings, steering-wheel-activity, and host-vehicle-speed.

Accordingly, a driver-fatigue warning system <NUM>, a controller <NUM> for the driver-fatigue warning system <NUM> and a method <NUM> of operating the driver-fatigue warning system <NUM> is provided. The system <NUM> reduces the rates of the false driver-fatigue warning by determining when to count <NUM> the lane-departure <NUM>, which may help to reduce occurrences of operators <NUM> intentionally deactivating the driver-fatigue warning system <NUM>. By not counting <NUM> the occurrences of the lane-departures <NUM> under the conditions described above, the system <NUM> does not penalize the operator <NUM> of the host-vehicle <NUM> when the operator <NUM> makes an intentional lane-departure <NUM>. The operator <NUM> may make the intentional lane-departure <NUM> to provide greater clearance between the host-vehicle <NUM> and the detected object <NUM> that may be perceived as a hazard by the operator <NUM>.

Claim 1:
A method (<NUM>) of operating an alert device of a vehicle (<NUM>; <NUM>), the method (<NUM>) comprising:
I) capturing (<NUM>), by a camera (<NUM>, <NUM>), an image (<NUM>, <NUM>) including a lane marking (<NUM>, <NUM>) on the left-side and on the right-side of the travel lane (<NUM>) of a roadway (<NUM>, <NUM>) of the host vehicle (<NUM>), and an object (<NUM>, <NUM>) proximate to the vehicle (<NUM>, <NUM>);
II) determining (<NUM>), with a controller (<NUM>, <NUM>) in communication with the camera (<NUM>, <NUM>), a vehicle offset (<NUM>, <NUM>) between the vehicle (<NUM>, <NUM>) and the lane marking (<NUM>, <NUM>) based on the image (<NUM>, <NUM>), the vehicle offset (<NUM>) being a measure of a distance from the left-side and the right-side of the host vehicle (<NUM>) to the lane-marking (<NUM>);
III) determining (<NUM>), based further on the image (<NUM>, <NUM>), an object offset (<NUM>, <NUM>) between the object (<NUM>, <NUM>) and the lane marking (<NUM>, <NUM>);
IV) determining (<NUM>) occurrences of lane departures (<NUM>, <NUM>) by the vehicle (<NUM>, <NUM>) when the vehicle offset (<NUM>, <NUM>) is less than a deviation threshold (<NUM>, <NUM>),
V) incrementing a count (<NUM>, <NUM>) for each of the occurrences of lane departures (<NUM>, <NUM>);
VI) refraining from incrementing the count (<NUM>, <NUM>) in response to determining that the object offset (<NUM>, <NUM>) is less than an offset threshold (<NUM>, <NUM>) and a greater clearance between the vehicle (<NUM>, <NUM>) and the object (<NUM>, <NUM>) is provided by the lane departure (<NUM>, <NUM>); and
responsive to
VII) determining that the count (<NUM>, <NUM>) of the occurrences of lane departures (<NUM>, <NUM>) exceeds a crossing threshold (<NUM>) indicative of driver fatique,
VIII) activating (<NUM>) an alert device (<NUM>, <NUM>) to alert an operator (<NUM>, <NUM>) of the host vehicle (<NUM>, <NUM>) of driver fatigue.