DE202010018440U1 - A device for assisting a driver in controlling a vehicle along a bottleneck - Google Patents

Abstract

A device for assisting a driver in controlling a vehicle (100) along a bottleneck, in particular a construction site, the device comprising: • a bottleneck detection unit (102) adapted to detect bottleneck information for characterizing a bottleneck in which the vehicle 100) is located; • a bottleneck information processing unit (104) configured to process the detected bottleneck information to derive therefrom assistance information for assisting the driver in controlling the vehicle (100) along the bottleneck; A drive unit (106), which is set up to drive a light source (108) of the vehicle (100), such that the light source (108) generates a driver-visible light pattern (110) outside the vehicle (100), which is the driver's the support information is visualized, wherein the drive unit (106) for driving the light source (108) of the vehicle (100) is set up such that the light source (108) generates the light pattern (110) with a visual code that informs the driver of the actual distance of the vehicle Vehicle (100) to a lane edge or to a lane boundary barrier (112) bounding the lane (114), the visual code being a spatially spaced pair of light structures or a time spaced light pattern (110).

Description

The invention relates to a device for assisting a driver in controlling a vehicle along a bottleneck.

Furthermore, the invention relates to a vehicle.

Moreover, the invention relates to a program element.

The invention further relates to a computer-readable storage medium.

Vehicle lighting is the illumination of vehicles, which is necessary to be seen at twilight, darkness or in bad weather conditions on roads and to see enough itself.

Conventional vehicles do not include any functions that allow a user to cope with difficult driving situations such as driving in the area of bottlenecks, in particular construction sites.

The invention has for its object to provide a vehicle system in which a driver with a high level of operator comfort can navigate a vehicle in the area of bottlenecks.

This object is achieved by the subject matter of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, there is provided an apparatus for assisting a driver in controlling a vehicle along a bottleneck, the apparatus comprising a bottleneck detection unit configured to detect bottleneck information for characterizing a bottleneck (in particular, for detecting a lateral distance of the vehicle from a throat boundary). in which the vehicle is located, a bottleneck information processing unit configured to process the detected bottleneck information, to derive therefrom assistance information for assisting the driver in controlling the vehicle along the bottleneck, and a drive unit adapted to drive a light source of the vehicle Vehicle is set up such that the light source generates a viewable for the driver light pattern that visualizes the driver support information (that is accessible to the driver's eye sense makes power). According to an exemplary embodiment, the light pattern may be displayed to the driver, in particular outside the vehicle (in particular along its line of vision) (that is, the light pattern may be projected onto a body located outside the vehicle and provided separately from the vehicle, for example one) Surface of a road boundary barrier).

According to another aspect of the invention, a vehicle (eg, a motor vehicle, particularly a passenger car or a truck or a motorcycle) is provided with a device having the above features. The vehicle may also be an aircraft such as an aircraft or a watercraft such as a ship.

According to another aspect, there is provided a method of assisting a driver in controlling a vehicle along a bottleneck, the method detecting bottleneck information for characterizing the bottleneck in which the vehicle is located, processing the detected bottleneck information to provide support information therefrom deriving the driver along the bottleneck in controlling the vehicle, and a light pattern visible to the driver is generated in such a way that the support information is visualized to the driver. According to one exemplary embodiment, the light pattern can be displayed to the driver, in particular outside the vehicle.

In a computer-readable storage medium according to an embodiment of the present invention, a program for assisting a driver in controlling a vehicle along a bottleneck is set, which program is set up to execute or control the method having the above-described features when executed by a processor.

A program element (computer program element) according to an embodiment of the present invention has (or controls) the method steps described above when executed.

Embodiments of the present invention can be realized both by means of a computer program, that is to say a software, and by means of one or more special electrical circuits, that is to say in hardware, or in any hybrid form, that is to say by means of software components and hardware components.

In the context of this application, the term "bottleneck" is understood to mean, in particular, a local area of a driving route (in particular a road) having a reduced roadway width (for example compared to another normal width), for example with narrowed tracks. Such a locally narrowed roadway width, for example, by Lane boundary barriers are defined as they occur on construction sites, in narrow streets with structures close to the roadway and in similar situations. In the case of a bottleneck, one or more barriers may limit the free travel compared to a conventional driving situation in which accessibility prevails at the edge of the roadway. Thus, a bottleneck can also represent a particular source of danger with regard to traffic accidents. It is possible according to an embodiment that the presence of a bottleneck is assumed upon fulfillment of one or more detected decision criteria. An example of such a decision criterion is that a lateral distance of the vehicle to a roadway edge and / or to a road boundary barrier falls below a predefinable threshold value. Another decision criterion would be that at the same time a predefinable minimum speed of the vehicle is exceeded. Another decision criterion would be that, for example, a bottleneck warning sign, for example a construction site warning sign, is detected by means of image recognition.

By "bottleneck information" is meant in particular geometrical information concerning the spatial arrangement of one or more components at the bottleneck with each other or their relative position or relative distance to the vehicle. Such a component may be, for example, a lane boundary barrier or a lane boundary line. For example, bottleneck information can be sensed by means of the bottleneck detection unit, in particular using one or more distance sensors, which detect in particular the lateral distance of the vehicle to components in the environment (road boundary barrier, adjacent vehicle on another lane). In the preferably contactless distance determination, the sensor detects, for example, the direction and / or transit time of an actively emitted signal reflected on the component. The actively emitted measuring beams of distance sensors are, for example, light, infrared radiation, radio waves, microwaves or ultrasound.

The term "support information" is understood in particular to be a driver provide information that facilitates the driver's control of the vehicle through the bottleneck and warn him in particular about impending dangers such as too close to a limitation of the bottleneck. Generating support information may include determining data that provides at least a visual indication of the distance of the vehicle from an obstacle or other information when the data is used to control the light source.

In the context of this application, a "light pattern" can be understood in particular to be a structured arrangement of contiguous or non-contiguous light spots, in which information is intuitively communicated to the driver. This information can be encoded in the spatial distance of certain patches from each other, in the temporal sequence of light signals and / or in the structure or size of the light pattern.

In the context of this application, the various units can be understood in particular to mean processors, each of which forms one of the units. But it is also possible that several or all of the units are implemented in a common processor, for example in a microprocessor or a CPU (Central Processing Unit).

According to an exemplary embodiment of the invention, a system is provided which provides a driver in a special situation with narrowed driving range, for example at a construction site, additional information that facilitates the driver to navigate through the bottleneck. Such a system may derive driver-relevant information based on data collected from the environment, such as the distance of the vehicle from a bottleneck limitation, to provide the driver with safe navigational navigation through the bottleneck in this unfamiliar and particularly hazardous situation. For this purpose, a drive unit controls one or more light sources of the vehicle such that a generated structured light pattern intuitively gives the driver information about the vehicle condition relative to the bottleneck. As a result, improved driving safety is made possible with high user comfort. For example, at off-highway construction sites (eg, concrete blocks), a driver may be given the difficulty of estimating a distance of the vehicle to the perimeter development and the driver may be presented with distance information in the form of an intuitive visual code that the driver can comfortably perceive without the driver Focus on controlling the vehicle would be compromised.

In the following, further embodiments of the device will be described. These also apply to the vehicle, the procedure, the program element and the computer-readable storage medium.

According to one embodiment, the bottleneck detection unit may include an image capture unit for capturing at least one image of the bottleneck. For example, bottleneck detection may be based on optical data that may be captured by one or more cameras. For example, a Camera oriented along the line of sight of a driver. It is alternatively or additionally possible, in particular laterally attached to the vehicle one or more cameras to provide information that the driver can not or can not easily see in his line of sight. As an alternative or in addition to providing one or more cameras or image recording units, it is also possible to use other sensors that provide information about the bottleneck. For example, a distance measurement can also take place via radar, time-of-flight measurements of radiation, infrared cameras or the like. An image can not only be an optical image, but can also be a thermal image or derived from ultrasound measurements.

In one embodiment, the assistance information may include information regarding a position of the vehicle, a lane width, a lane barrier position, a lane of the vehicle from a lane boundary barrier, and / or a distance of the vehicle from an adjacent lane. Such information is helpful in avoiding that a driver particularly required in a construction site situation bounces his / her vehicle laterally against an obstacle such as another vehicle or a vehicle boundary barrier, for example.

According to an embodiment, the drive unit for driving the light source of the vehicle may be configured such that the light source generates the light pattern in addition to or independent of a headlight illumination of the vehicle. In other words, the structured light pattern, which provides the driver with special information regarding the bottleneck, may be provided separately from the headlight illumination. This separate provision is to be understood functionally such that the headlight illumination can be selectively activated or deactivated separately from or in conjunction with the light pattern. The light pattern can be turned on custom by a user pressing a corresponding switch or other actuator. But it is also possible that automatically recognizes a bottleneck based on one or more decision criteria, a processor automatically turns on the bottleneck lighting when such a bottleneck is detected.

According to one exemplary embodiment, the drive unit for activating the light source of the vehicle may be set up in such a way that the light source projects the light pattern onto the roadway or onto a road boundary barrier bounding the roadway. The light pattern can also be directed and projected to other destinations outside (or inside) the vehicle. Thus, the light pattern can be projected to a desired location that allows a user to perceive the light pattern from his seated position during travel of the vehicle. In particular, when the structured light pattern is projected onto a road boundary barrier of a construction site, the bottleneck information can be displayed to the user, without the overlaying of a headlight illumination or the like being limited to perceptibility.

According to one exemplary embodiment, the drive unit for activating the light source of the vehicle can be set up such that the light source generates the light pattern with a visual code that indicates to the driver the current distance of the vehicle from a lane edge or a lane boundary barrier delimiting the lane. Such a code may be configured to intuitively provide a user with important information about the current vehicle condition as it passes the bottleneck. By displaying the actual distance to a lane boundary or a lane boundary barrier, a collision with such an object is reliably avoided and ensured that the driver steers the vehicle at the correct position through the bottleneck.

Optionally, the visual code may be represented by an audible code (eg, a tone or tone sequence whose pitch or time interval or duration thereof is a measure of the vehicle's distance to a lateral barrier) and / or a haptic Code (for example, a vibration of the steering wheel, the time interval or the intensity of which is a measure of a distance of the vehicle to a side barriers) are supplemented.

According to one embodiment, the code may be a spatially spaced pair of light structures (eg, a pair of light points, a pair of lines of light or a pair of circles) or a time-spaced pattern of light (eg, a flashing light structure). For example, if the code is a spatially spaced pair of light structures, then the current spacing of the two light structures may be selected to be proportional to a current distance of the vehicle from a roadway boundary. As the vehicle's current distance to a vehicle boundary barrier or lane edge changes, so does the distance between the two light spots that are projected to an appropriate location. As an alternative to the distance between two points of light, the distance of the vehicle to the edge of the road or Fahrbahnbegrenzungsbarriere be performed by a temporal spacing of a light pattern, for example by flashing a point or a light pattern, the flashing frequency can be set higher, the smaller the distance of the vehicle to the lane boundary barrier. Other codes are possible, such as the coding of the distance in terms of the size of a light pattern. For example, if the light pattern is realized as a circular area, then the circle diameter may be selected to be proportional to the actual distance of the vehicle to the roadway boundary. It is also possible that this visual code is combined with another code, for example an audible alarm and / or a haptic alarm (for example vibration of the steering wheel) if the current distance falls below a predefinable threshold.

According to one exemplary embodiment, the drive unit for activating the light source of the vehicle can be set up such that the light source generates the light pattern as a light pattern with time-variable color, as a multicolored color pattern, an arrangement of multiple light points, brightness patterns and / or as a time-varying pattern. In a multicolor color pattern, that is, a color pattern containing different wavelength ranges of visible light in different spatial and / or temporal portions, information may be encoded in the colors. For example, red may indicate special hazard information (for example, if the distance is below a dangerous minimum). At a higher, but still critical distance, the light structure can take on a yellow color (for example if the distance is adjusted below another predefinable threshold value). At even higher, sufficient distance, the light structure may have a green color (for example, when the distance is within a desired interval). The multicolor can either vary in time or can vary spatially. When providing a plurality of light spots, their spacing and / or their size may include support information. In the case of a brightness pattern, the information can be coded in terms of brightness. In a time-varying pattern, for example, the information may be encoded in a blinking frequency or the like.

According to one embodiment, the device may further comprise the light source, which may be formed as a headlight or as part of a headlight of the vehicle. Thus, the light source can be used as part of the headlamp, which ensures a compact design. But it is also possible that the light source is provided separately from the headlights.

It should be noted that embodiments of the invention have been described with reference to different subject matters. described. However, it will be readily apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features belonging to a type of subject matter, any combination of features that may result in different types of features is also possible Subject matters belong.

Further advantages and features of the present invention will become apparent from the following exemplary description of presently preferred embodiments. The individual figures of the drawing of this application are merely to be regarded as schematic and not to scale.

1 shows a system for assisting a driver in controlling a vehicle along a construction site according to an exemplary embodiment of the invention.

2 and 3 show a vehicle in a bottleneck according to an exemplary embodiment of the invention.

The same or similar components in different figures are provided with the same reference numerals.

Embodiments of the invention include a special control of the headlights for optimal street illumination within a construction area.

In particular, embodiments of the invention provide an apparatus for presenting additional information to a driver by means of additional lighting. The information can be coded by structuring a light pattern.

A construction site assistant according to an embodiment of the invention is intended to assist a driver when driving on construction sites, where lanes are tight and the lane boundary are formed on one or both sides by fixed high barriers.

It can be displayed to the driver light marks (structured light) on the boundaries or the road, which make it easier, the road width, the current position of the vehicle on the lane and the distance of the vehicle to the road-bounding buildings (barriers, road divider, etc.) better estimate.

One embodiment includes an image recording unit, a recorded image processing unit, and one or more drive units for generating the structured light described below.

• – die Baustellensituation und/oder
• – fahrbahnbegrenzende Bebauung und/oder
• – die Position des Fahrzeugs in Bezug zu den Fahrstreifen und der Fahrbahn begrenzenden Bebauung

With the help of the image-recording unit and an image-processing unit, the traffic situation ahead of the vehicle is detected. In particular, it can be recognized:

• - the site situation and / or
• - road-bounding development and / or
• - The position of the vehicle in relation to the lanes and the road bounding development

The information that the vehicle is within the above situation, the current position of the vehicle within the lanes, and / or the nature and location of the lane delimiting objects are used to generate structured light. The structured light is projected onto the barriers or the roadway.

• 1. Das strukturierte Licht wird zusätzlich zu dem normalen Licht erzeugt.
• 2. Es wird derart erzeugt, dass keine Blendung des Gegenverkehrs stattfinden kann.
• 3. Das strukturierte Licht ist so ausgestaltet, dass es vom Fahrer aus leicht zu erkennen ist.
• 4. Des Weiteren soll die Struktur des Lichtes den Fahrer dabei unterstützen, die Breite seiner Fahrspur und speziell den Abstand zur fahrbahnbegrenzenden Bebauung abzuschätzen.
• 5. Die Strukturierung kann unter anderem durch unterschiedliche Farbmuster, durch Helligkeitsmuster oder durch sich zeitlich ändernde Muster (zum Beispiel Pulsieren) erzeugt werden.

The structured light is characterized according to an embodiment of the invention by the following properties:

• 1. The structured light is generated in addition to the normal light.
• 2. It is generated in such a way that no glare of oncoming traffic can take place.
• 3. The structured light is designed so that it is easy to see from the driver.
• 4. Furthermore, the structure of the light to help the driver to estimate the width of his lane and especially the distance to the road-bounding development.
• 5. The structuring can be produced inter alia by different color patterns, by brightness patterns or by temporally changing patterns (for example pulsation).

An actuator may be used to generate the structured light according to specifications of the processing unit.

1 shows a motor vehicle 100 according to an exemplary embodiment of the invention. The car 100 includes a system for assisting a driver (not shown) in controlling the vehicle 100 along a construction site. Such a construction site situation is in 1 shown where a roadway 114 is narrowed compared to a conventional width, in the embodiment shown by the two-sided provision of road boundary barriers 112 ,

According to 1 For example, a bottleneck detection unit configured as an image pickup device is provided which includes four separate optical cameras 102 wherein in other embodiments a different (for example ultrasound-based) image recording arrangement or any other sensor technology may be provided. One of these cameras 102 is arranged to take pictures in the direction of travel, two of the cameras 102 are arranged laterally for taking pictures and the fourth camera 102 looks against the direction of travel of the vehicle 100 , Alternatively to the shown arrangement with four cameras 102 Any other number is possible, in particular, can also be a single or two, for example, laterally oriented cameras 102 be enough. The cameras 102 detect information concerning the construction site situation, in particular distances d ₁ and d _{2 of} the vehicle 100 to the respective barriers 112 ,

The optical camera data are from the cameras 102 to a bottleneck information processing unit 104 transmitted. This is set up by the cameras 102 to detect detected bottleneck information to provide assistance information for assisting the driver in controlling the vehicle 100 to derive along the bottleneck shown. Such assistance information is an intuitive display of a current distance of the vehicle that can be visually presented to the driver 100 from the road boundary barriers 112 , In other words, the bottleneck information processing unit 104 a processor capability to calculate distance information or the like from the optical image data and to determine the visual representation.

When this is done, the bottleneck information processing unit provides 104 a drive unit 106 the support information in the form of electrical signals ready. The drive unit 106 is for driving light sources 108 in the headlights of the vehicle 100 are housed or form part of it. The control takes place in such a way that the light sources 108 a light pattern visible to the driver 110 generate, which makes the support information optically accessible to the driver. In other words, the light sources generate 108 under control of the drive unit 106 such a light pattern 110 in that the driver provides the assistance information by viewing the light pattern 110 can perceive this when looking at an object such as the roadway 114 or one of the lane boundary barriers 112 is directed.

Furthermore, in 1 an input / output unit 114 which may also be referred to as a user interface. This enables a driver (or other user such as a passenger) to selectively turn on or off the construction site light, set operating parameters to be user-defined, etc. Thus, the input / output unit is 114 , which may include buttons, a touchpad, a keyboard, etc., bidirectionally communicable with the bottleneck information processing unit 104 coupled.

For example, a flashing frequency of the patterned light pattern 110 the higher the smaller the distance d ₁ is. Furthermore, a flashing frequency of another light pattern 110 ' be set so that it is higher, the smaller the distance d ₂ . Intuitively, the characteristic of the distance d ₁ light pattern 110 The left side of the driver projects, whereas the other light pattern 110 ' , which is characteristic of the distance d ₂ , is projected onto the right side of the driver.

2 and 3 show two different scenarios in a construction site situation.

2 shows the vehicle 100 on the left lane. This lane is left in the direction of travel through the barrier 112 limited. 3 shows the vehicle 100 also on the left lane, but closer to the barrier 112 , 2 and 3 also show markings of a median strip 204 ,

2 and 3 also represent how by a distance A or A 'of two points of light 200 . 202 from each other to a distance d ₁ or d ₁ 'to the barrier 112 can be closed. How out 2 and 3 can be seen, is dependent on the respective distance d ₁ or d ₁ 'to the barrier 112 also the distance A or A 'of the points of light 200 . 202 different from each other, and correspondingly also the average distance M or M 'of the points of light 200 . 202 to the vehicle 100 ,

As an example of structured construction site light is in 2 and 3 the generation of the two beams of light 110 accepted. These rays of light 110 generate the points 200 . 202 on the surface of the barrier 112 ,

The difference between 2 and 3 is the distance of the vehicle 100 to the barrier 112 , With the distance between vehicle 100 and barrier 112 the distance between the dots changes 200 . 202 to each other, but also the mean distance between the two points 200 . 202 to the vehicle 100 , Based on this information, the driver can see the location of his vehicle 100 in relation to the barrier 112 better estimate.

It should be noted that the embodiments described herein represent only a limited selection of possible embodiments of the invention. Thus, it is possible to suitably combine the features of individual embodiments with one another, so that for the person skilled in the art with the variants of embodiment that are explicit here, a multiplicity of different embodiments are to be regarded as obviously disclosed.

Claims (10)

Device for assisting a driver in controlling a vehicle ( 100 ) along a bottleneck, in particular a construction site, wherein the device comprises: • a bottleneck detection unit ( 102 ) arranged to detect bottleneck information for characterizing a bottleneck in which the vehicle ( 100 ) is located; A bottleneck information processing unit ( 104 ) configured to process the detected bottleneck information to derive therefrom assistance information for assisting the driver in controlling the vehicle ( 100 ) to be derived along the bottleneck; A drive unit ( 106 ), which are used to drive a light source ( 108 ) of the vehicle ( 100 ) is set up such that the light source ( 108 ) a light pattern visible to the driver ( 110 ) outside the vehicle ( 100 ) that visualizes the support information to the driver, wherein the drive unit ( 106 ) for driving the light source ( 108 ) of the vehicle ( 100 ) is set up such that the light source ( 108 ) the light pattern ( 110 ) is generated with a visual code which gives the driver the actual distance of the vehicle ( 100 ) to a lane edge or to a lane ( 114 ) limiting road boundary barrier ( 112 ), wherein the visual code comprises a spatially-spaced pair of light patterns or a time-spaced light pattern ( 110 ). Device according to claim 1, wherein the bottleneck detection unit ( 102 ) has an image pickup unit for picking up at least one image of the bottleneck. An apparatus according to claim 1 or 2, wherein said assistance information is information regarding a position of the vehicle ( 100 ), a lane width, a position of a lane boundary barrier ( 112 ), a distance of the vehicle ( 100 ) of a road boundary barrier ( 112 ) and / or a distance of the vehicle ( 100 ) from an adjacent lane. Device according to one of claims 1 to 3, wherein the drive unit ( 106 ) for driving the light source ( 108 ) of the vehicle ( 100 ) is set up such that the light source ( 108 ) the light pattern ( 110 ) in addition to or independent of a headlight illumination of the vehicle ( 100 ) generated. Device according to one of claims 1 to 4, wherein the drive unit ( 106 ) for driving the light source ( 108 ) of the vehicle ( 100 ) is set up such that the light source ( 108 ) the light pattern ( 110 ) on the roadway ( 114 ) or on a lane ( 114 ) limiting road boundary barrier ( 112 ) projected. Device according to one of claims 1 to 5, wherein the drive unit ( 106 ) for driving the light source ( 108 ) of the vehicle ( 100 ) is set up such that the light source ( 108 ) the light pattern ( 110 ) as a multicolor color pattern, an arrangement of multiple light structures, brightness patterns and / or generated as a time-varying pattern. Device according to one of claims 1 to 6, further comprising the light source ( 108 ) as a headlamp or as part of a front headlamp of the vehicle ( 100 ) is trained. Vehicle ( 100 ), comprising a device for assisting a driver in controlling a vehicle ( 100 ) along a narrow point, in particular a construction site, according to one of claims 1 to 7. Computer-readable storage medium in which a program for assisting a driver in controlling a vehicle ( 100 ) is stored along a bottleneck, in particular a construction site, which program for carrying out or controlling a method for assisting a driver in controlling a vehicle ( 100 ) along a bottleneck, in particular a construction site, the method comprising: • detecting bottleneck information for characterizing the bottleneck in which the vehicle ( 100 ) is located; Processing the detected bottleneck information to derive therefrom support information for assisting the driver in controlling the vehicle ( 100 ) to be derived along the bottleneck; • controlling a light source ( 108 ) of the vehicle ( 100 ) such that the light source ( 108 ) a light pattern visible to the driver ( 110 ) outside the vehicle ( 100 ), which visualizes the support information to the driver, wherein the light source is controlled in such a way that the light source ( 108 ) the light pattern ( 110 ) is generated with a visual code which gives the driver the actual distance of the vehicle ( 100 ) to a lane edge or to a lane ( 114 ) limiting road boundary barrier ( 112 ), wherein the visual code comprises a spatially-spaced pair of light patterns or a time-spaced light pattern ( 110 ). Program element for assisting a driver in controlling a vehicle ( 100 ) along a bottleneck, particularly a construction site, when executed by a processor to perform or control a method of assisting a driver in controlling a vehicle ( 100 ) along a bottleneck, in particular a construction site, the method comprising: • detecting bottleneck information for characterizing the bottleneck in which the vehicle ( 100 ) is located; Processing the detected bottleneck information to derive therefrom support information for assisting the driver in controlling the vehicle ( 100 ) to be derived along the bottleneck; • controlling a light source ( 108 ) of the vehicle ( 100 ) such that the light source ( 108 ) a light pattern visible to the driver ( 110 ) outside the vehicle ( 100 ), which visualizes the support information to the driver, wherein the light source is controlled in such a way that the light source ( 108 ) the light pattern ( 110 ) is generated with a visual code which gives the driver the actual distance of the vehicle ( 100 ) to a lane edge or to a lane ( 114 ) limiting road boundary barrier ( 112 ), wherein the visual code comprises a spatially-spaced pair of light patterns or a time-spaced light pattern ( 110 ).

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