Lane marking crossing warning system

A lane marking crossing warning system for a vehicle includes a sensor arrangement arranged to detect at least one lane marking line that defines a corresponding lane boundary, a control unit arranged to determine if the vehicle has entered a curve, and a warning device arranged to issue a warning. When the control unit has determined that the vehicle has entered a curve, the control unit is arranged to determine if an imaginary sensor line running a certain distance from the lane marking line has been crossed by the vehicle. If that is the case, the control unit is arranged to determine that a warning is to be issued by the warning device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates to PCT International Patent Application No. PCT/SE2012/050485, filed on May 8, 2012.

FIELD OF THE INVENTION

The present invention relates to a lane marking crossing warning system for a vehicle. The warning system including:

a sensor arrangement arranged to detect at least one lane marking line that defines a corresponding lane boundary,

a control unit arranged to determine if the vehicle has entered a curve, and

warning means, arranged to issue a warning.

The present invention also relates to a method for lane marking crossing warning in a vehicle, where the method includes the steps:

detecting at least one lane marking line, and determining if the vehicle is travelling in a curve.

BACKGROUND

Lane departure warning and avoidance (LDW) systems have been developed to aid vehicle drivers in maintaining proper lane alignment by providing a warning if lane markings are crossed, some LDW systems provide timely warnings prior to crossing of lane markings.

Present LDW systems typically utilize radars, digital maps, camera/video processing sensors or other suitable sensor arrangement to detect lane markings that define a lane boundary. The detected lane markings determine the lateral position of a vehicle in a lane. Present LDW systems further usually have an analyzer for analyzing the crossing of lane markings, and suitable means for warning a driver of lane departure as necessary. An estimated time for lane crossing may be determined, and when this time falls below a predefined threshold, a warning is typically issued.

However, in order to obtain a comfortable and efficient driving of a vehicle, it is often desired to cross lane marking in a curve if possible due to the traffic situation, reducing the curvature of the vehicle's path. In this case warnings from an LDW system would constitute non-relevant warnings that unnecessarily distract the driver.

The documents U.S. Pat. No. 7,561,032 and US Publication No. 2005/273264 describe LDW systems that adapt to different styles of driving, and suppress warnings when found appropriate. However, it is desired that a higher degree of safety is obtained, while maintaining the possibility to reduce the curvature of the vehicle's path without receiving unnecessary warnings.

It is therefore an object of the present invention to provide a device for warning a driver in the event of expected or occurred lane marking crossing, which allows driving safety to be improved and at the same time the number of unnecessary warnings to be minimized.

The object is achieved by means of a lane marking crossing warning system for a vehicle in accordance with this invention. The warning system described herein includes:

a sensor arrangement arranged to detect at least one lane marking line that defines a corresponding lane boundary;

a control unit arranged to determine if the vehicle has entered a curve; and

warning means, arranged to issue a warning.

When the control unit has determined that the vehicle has entered a curve, the control unit is arranged to determine if an imaginary sensor line running a certain distance from the lane marking line has been crossed by the vehicle. In that case, the control unit is furthermore arranged determine that a warning is to be issued by the warning means.

The above object is also achieved by means of a method for lane marking crossing warning in a vehicle, where the method includes the steps:

detecting at least one lane marking line, determining if the vehicle is travelling in a curve and, if the vehicle has been determined to travel in a curve, issuing a warning to a vehicle driver if an imaginary sensor line, running a certain distance from said lane marking line, is crossed by the vehicle.

According to an example embodiment of the invention, each sensor arrangement includes a camera device.

According to another example embodiment, the control unit arranged to determine if the vehicle has entered a curve based on input from:

the sensor arrangement and/or

a steering wheel angle sensor and/or

a vehicle yaw sensor and/or

a digital map system.

According to another example embodiment, when the control unit has determined that the vehicle has entered a curve, the control unit is further arranged to move each sensor line, from coinciding with said lane marking line, to running said certain distance from said lane marking line.

According to another example embodiment, for a curve turning to the left with regard to a vehicle travelling direction, the control unit is arranged to move at least one sensor line to the left. Correspondingly, for a curve turning to the right with regard to the vehicle travelling direction, the control unit is arranged to move at least one sensor line to the right.

Other examples are disclosed herein.

A number of advantages are obtained by means of the present invention. Mainly, a lane marking crossing warning system is provided, which system allows driving safety to be improved while the number of unnecessary warnings is minimized.

DETAILED DESCRIPTION

With reference toFIG. 1, showing a side view of a vehicle1, the vehicle1includes a sensor arrangement2arranged to detect road lane marking lines that define a lane boundary and a control unit3arranged to determine if a warning is to be issued, and if so, issues such a warning. The warning may for example be in the form of a displayed message and/or a sound or voice message as well as vibrations created for a steering wheel, and generally the warning is issued or created by means of warning means13. As shown inFIG. 1, the sensor arrangement2is connected to the control unit3, which in turn is connected to the warning means13.

FIG. 2shows a first example, where the vehicle1is moving in a direction D along a road4with two lanes4a,4bseparated with lane marking lines in the form of a dashed line5. The road's outer boundaries are marked with lane marking lines in the form of a first solid line6and a second solid line7, the vehicle1being shown travelling in a first lane4abetween the dashed line5and the first solid line6. The control unit3issues a warning if a first sensor line8aor a second sensor line8bis crossed. The sensor lines8a,8bare indicated with dash-dotted lines, only being imaginary and used by the control unit3only. At the travelling position shown for the vehicle1, the first sensor line8acoincides with the dashed line5and the second sensor line8bcoincides with the first solid line6. The second sensor line8bis thus not visible inFIG. 2since it coincides with the first solid line6.

Ahead of the vehicle in its travelling direction D there is a curve9that turns to the left. When the vehicle approaches the curve9, the steering is moved to a position first indicated with a first line L1. When the vehicle1has travelled a certain time t that corresponds to a first distance10, a certain second position indicated with a second line L2is reached. At the second line L2, the control unit3determines that the vehicle1is travelling in a curve.

According to the present invention, when the control unit3has determined that the vehicle1is travelling in a curve, the control unit3moves the first sensor line8aand the second sensor line8bsuch that a moved first sensor line8a′ and a moved second sensor line8b′ are formed. The moved first sensor line8a′ has been moved, away from the first solid line6, such that it follows the shape of the dashed line5a certain first line distance11from the dashed line5. The moved second sensor line8b′ has been moved, towards the dashed line5, such that it follows the shape of the first solid line6a certain second line distance12from the first solid line6.

Since the first sensor line8ahas been moved, the vehicle1may cross the dashed line5without any warning being issued; the warning still being issued if the moved first sensor line8a′ is crossed.

On the other hand, the second sensor line8bhas been moved towards the dashed line5, a warning being issued if the moved second sensor line8b′ is crossed, which occurs before the first solid line6is crossed. In this way, a warning is issued if the vehicle1comes too close to the first solid line6, which is undesired in order to be able to pass the left-turning curve9in a safe manner.

The first lane4aas defined by the sensor lines8a,8bhas been moved to the left in the curve9that turns to the left. If the line distances11,12are equal, the width of the first lane4ais maintained.

InFIG. 3, showing a second example, a similar situation is shown where the vehicle1is moving in the direction D along the road4. As before, the vehicle1is shown travelling in the first lane4abetween the dashed line5and the first solid line6.

Ahead of the vehicle in its travelling direction D there is a curve9′ that turns to the right. When the vehicle1approaches the curve9′, the steering equipment is deflected to a certain degree at a certain position first indicated with a first line L1′. When the vehicle1has travelled a certain time t′ that corresponds to a first distance10′ without reducing the deflection, a certain second position indicated with a second line L2′ is reached. At the second line L2′, the control unit3determines that the vehicle1is travelling in curve.

When the control unit3has determined that the vehicle1is travelling in a curve, the control unit3moves the first sensor line8aand the second sensor line8bsuch that a moved first sensor line8a′ and a moved second sensor line8b′ are formed. The moved first sensor line8a′ has been moved, towards the first solid line6, such that it follows the shape of the dashed line5a certain first line distance11from the dashed line5. The moved second sensor line8b′ has been moved, away from the dashed line5, such that it follows the shape of the first solid line6a certain second line distance12from the first solid line6.

Since the first sensor line8ahas been moved, the vehicle1may cross the first solid line6without any warning being issued; the warning still being issued if the moved second sensor line8b′ is crossed.

On the other hand, the first sensor line8ahas been moved towards the first solid line6, a warning being issued if the moved first sensor line8a′ is crossed, which occurs before the dashed line5is crossed. In this way, a warning is issued if the vehicle1comes too close to the dashed line5, which is undesired in order to be able to pass the right-turning curve9′ in a safe manner.

The first lane4aas defined by the sensor lines8a,8bhas been moved to the right in the curve9′ that turns to the right. If the line distances11,12are equal, the width of the first lane4ais maintained.

With reference toFIG. 4, an alternative to the first example described previously with reference toFIG. 2will be described. Here, the difference lies in the fact that when the control unit3has determined that the vehicle1is travelling in a curve9turning to the left, the control unit3moves only the first sensor line8asuch that a moved first sensor line8a′ is formed. The moved first sensor line8a′ has been moved, towards the first solid line6, such that it follows the shape of the dashed line5a certain first line distance11from the dashed line5as in the first example. The second sensor line8bhas not been moved.

Since the second sensor line8bhas not been moved, no warning is issued until the vehicle1crosses the first solid line6or the moved first sensor line8a′.

In this way, the first lane4aas defined by the sensor lines8a,8bhas been made wider, the first sensor line having been moved to the left in the curve9that turns to the left.

With reference toFIG. 5, an alternative to the second example described previously with reference toFIG. 3will be described. Here, the difference lies in the fact that when the control unit3has determined that the vehicle1is travelling in a curve9′ turning to the right, the control unit3moves only the second sensor line8bsuch that a moved second sensor line8b′ is formed. The moved second sensor line8b′ has been moved away from the dashed line5, such that it follows the shape of the first solid line6a certain second line distance12from the first solid line6as in the second example. The first sensor line8ahas not been moved,

Since the first sensor line8ahas not been moved, no warning is issued until the vehicle1crosses the dashed line5or the moved second sensor line8b′.

In this way, the first lane4aas defined by the sensor lines8a,8bhas been made wider, the second sensor line8bhaving been moved to the right in the curve9′ that turns to the right.

In all examples above, those sensor lines8a,8bthat have been moved during the curve9,9′, are returned to coincide with the corresponding lane markings5,6when the control unit3has determined that the vehicle1has left the curve9,9′. With reference toFIG. 1, the sensor arrangement2may be of many known types, for example it may have a camera device14and an image processing device15, the camera device14being mounted at a central rear-view mirror and facing the driving direction D. A typically measure of detection range is 5 meters. In order to obtain a correct estimate of the distance between the vehicle's wheels16a,16band the detected lane markings, the vehicle's width may be implemented in camera software, for example in the image processing device15or in the control unit3.

The control unit3determines that the vehicle1is travelling in a curve9,9′ at a certain position L1, L1′, and there are many ways to reach such a determination. For example:

The mentioned sensor arrangement2may be arranged to detect road curvature as well.

A steering wheel angle sensor17may be used where a typical threshold can be 8° -10° during 1 second —1,5 seconds, this time corresponding to the previously mentioned time t.

A vehicle yaw sensor18may be used to detect that the vehicle1enters a curve.

A digital map system such as a GPS (Global Positioning System) may be used to detect that the vehicle1enters a curve.

Combinations of the above may also be implemented along with any other sensor arrangement enabling detection of the vehicle entering a curve.

In the same way it is determined when the vehicle1has left the curve9,9′ in question.

The dashed line5and the solid lines6,7are only examples of lane marking lines. Less lane marking lines or more marking lines may occur, and they have many different shapes and characters. For the present invention, at least one lane marking lane is required.

As shown inFIG. 1, the present invention relates to a lane marking crossing warning system22for a vehicle1, the warning system22includes a sensor arrangement2arranged to detect at least one lane marking line5,6,7, a control unit3and warning means13.

With reference toFIG. 6, the present invention also relates to a method for providing lane marking crossing warning, the method including the steps of detecting19at least one lane marking line5,6; determining20if the vehicle (1) is travelling in a curve (9,9′); and if the vehicle1has been determined to travel in a curve9,9′, issuing a warning21to a vehicle driver if an imaginary sensor line8a,8b, running a certain distance11,12from the lane marking line5,6, is crossed by the vehicle1.

The present invention is not limited to the examples above, but may vary freely within the scope of the description. For example, the line distances11,12between the lane markings5,6and the corresponding sensor line8a,8bis about 0.1 meter to 0.3 meter.

The moving of the sensor lines8a,8bwhen the control unit3has determined that the vehicle1is travelling in a curve may be performed in one single step as shown in the previous examples, or gradually; either in several sub-steps or continuously.

It is normally desired to de-activate such a warning system in a city environment due to the usual abundant presence of curves in such an environment. It is also normally desired to de-activate such a warning system on roads with speeds over 90 km/h-100 km/h since the curves at such roads are longer with greater curvature radiuses. The warning system according to the present invention may therefore be arranged to be active in a certain speed range, for example 60 km/h-90 km/h or 50 km/h-100 km/h.

The sensor lines8a,8bmay have no practical width, but may be constituted by mathematical lines. Alternatively, the sensor lines8a,8bmay have a certain width. To determine if a sensor line8a,8bhas been crossed, a wheel16a,16bor other vehicle part may have been determined to have reached a sensor line8a,8b, or may have been determined to have passed a sensor line8a,8b. Due to the nature of such a detection, for example the tires of the wheels16a,16bnot being completely rigid, lane marking lines possibly being worn and/or re-painted and imperfections in calibrations, a crossing is normally not determined mathematically exact, but within what is practically obtainable.

Furthermore, there do not have to be any sensor lines that coincide with the lane marking lines5,6; the control unit3may be arranged to determine if lane marking lines have been crossed without sensor lines in this case. However, when the control unit3has determined that the vehicle1has entered a curve9,9′, the control unit3is arranged to determine if an imaginary sensor line8a,8brunning a certain distance11,12from said lane marking line5,6has been crossed by the vehicle1and in that case determine that a warning is to be issued by the warning means13. This means that the sensor lines at least are created when the control unit3has determined that the vehicle1has entered a curve9,9′.

The certain time t, t′ is preferably chosen such that driving maneuvers that do not relate to entering a curve do not cause the control unit3to erroneously determine that the vehicle1has entered a curve.