TECHNICAL FIELD OF THE INVENTION

The invention concerns a method and a calculating unit associated with a vehicle. More specifically, the invention concerns a mechanism for determining the lane position of a vehicle on a road.

BACKGROUND

A vehicle can use a warning system, sometimes referred to as Lane Departure Warning (LDW), to alert the vehicle driver that the vehicle is proceeding to cross a lane-marking line or to initiate an active intervention in order to prevent the vehicle from crossing the line, such as steering the vehicle in the opposite direction, or braking.

"Vehicle" refers in this context to, e.g. a goods vehicle, semi, transport vehicle, personal vehicle, emergency vehicle, car, all-terrain vehicle, tracked vehicle, bus, or other similar motorized manned or unmanned mode of transport adapted primarily for geographical movement on land.

Issuing a warning and/or taking accident-mitigating action enables the driver to be alerted to the circumstances that the lane-marking line is being crossed by the vehicle, e.g. because the driver has dozed or for some other reason lost focus on the road and the traffic situation. The vehicle can thus be prevented from driving off the road, or driving into the opposing lane and there causing a head-on collision with an oncoming vehicle.

Such a warning system in the vehicle comprises a camera that detects the lane- marking lines on the road and calculates the distance to said lane-marking lines by means of image processing.

One problem with existing warning systems as that they require that the camera in the vehicle be able to detect the lane-marking lines. However, lane-marking lines can often be indistinct or worn away as a result of traffic and/or inadequate maintenance. Furthermore, lane-marking lines can be entirely or partly covered by snow/ice (mainly in winter time), fallen leaves (mainly in the fall), water and/or sand (other seasons). Yet another problem with existing warning systems is that the camera is unable to see far enough in front of the vehicle to be able to detect the lane-marking lines, due to darkness, fog, severe precipitation or the like.

Furthermore in, for example, heavy traffic, the camera can sometimes be unable to detect the lane-marking lines because other surrounding vehicles are obstruct- ing its view.

As a consequence of this, the function of the warning system to warn the driver in the event of a lane crossing is disabled, with the result that the inattentive driver is, despite the warning system, at risk of driving off the road. Perhaps the vehicle warning system simply gives the driver a false sense of security, leading him to possibly relax and/or become involved in attention-intensive [activities] or to be busy with his mobile phone or the like to a greater extent than would have been the case had the vehicle had no warning system at all.

Yet another problem that can arise for the driver is that the road, including any lane-marking lines on the road, is covered with, for example, snow in wintertime. When driving, perhaps particularly over an open rural landscape and/or in poor visibility as a result of snowfall, darkness etc., it can be difficult for the driver to even see the stretch of road, which can cause the vehicle to drive into a ditch. Existing warning systems are of little or no help in such situations, as the camera is unable to detect any lane-marking lines. Furthermore, the camera in existing warning systems is sometimes unable to distinguish between the real lane-marking lines on the road and false lines in the road way resulting from tire tracks in, for example, slush, rubber skid marks resulting from vehicle braking/tire skids in the roadway, or quite simply discoloration or graffiti on the roadway. As a result, warning systems can come to generate false warnings and/or accident-avoiding action in the form of evasive maneuvers, which can surprise surrounding road users and thus cause near accidents. Furthermore, repeated false warnings of this type can irritate the driver and lead him to consequently turn off the warning system, which then results in the purpose of the warning system being obviated entirely.

It is clear that much remains to be done to achieve a reliable warning system in a vehicle to warn the driver that he is crossing lane-marking lines.

SUMMARY OF THE INVENTION

It is consequently an object of this invention to improve a warning system in a vehicle in order to solve at least one of the foregoing problems and thus achieve a vehicle improvement.

According to a first aspect of the invention, this object is achieved by means of a method in a calculating unit in a vehicle for determining the lane position of the vehicle on a road. The method comprises determining the geographical position of the vehicle. The method further comprises the detection, by means of a sensor, of a reference object associated with the road. The method further comprises the comparison, in a cartographic database, of stored lane-related data for the deter- mined geographical position to the detected reference object at said geographical position. The method further comprises the determination of the lane position of the vehicle by matching the detected reference object associated with the road with stored lane-related data for the determined geographical position of the vehicle. According to a second aspect of the invention, this object is achieved by means of a calculating unit in a vehicle, wherein the calculating unit is arranged so as to determine the lane position of the vehicle on a road. The calculating unit comprises a signal receiver arranged so as to receive a signal from a sensor contained in the vehicle, wherein the signal represents a detected reference object associated with the road. The calculating unit further comprises a processor circuit arranged so as to determine the geographical position of the vehicle. The processor circuit is also arranged so as to compare stored lane-related data for the determined geographical position to a detected reference object at said geographical position and to determine the lane position of the vehicle by matching the detected reference object with stored lane-related data for the geographical position of the vehicle.

Comparing reference points in the surroundings of the vehicle to stored lane- related data for the relevant geographical position thus enables a determination of the positions of the lane lines on a roadway, and a determination of the position of the vehicle in relation thereto. This thus enables greater access to the warning function for lane departures in situations in which the function is most needed, i.e. in connection with poor visibility and deficient road conditions, such as when the line markings on the road are covered with, for example, snow. According to certain embodiments, the number of false warnings is also reduced, as line detec- tions such as tire tracks in snow can be filtered out and rejected by the method, e.g. when the distance between two detected lines is unreasonable based on information from cartographic data. An improved warning system for line departures is thus achieved in a vehicle, which leads to a vehicle improvement.

Other advantages and additional new features will be evident from the following detailed description of the invention.

LIST OF FIGURES

The invention will now be described in greater detail with reference to the accompanying figures, which illustrate various embodiments of the invention:

Figure 1 illustrates an embodiment of a vehicle with a calculating unit according to one embodiment. Figure 2A illustrates a section of road viewed from above, with intact lane- marking lines on the road and a reference object associated with the road.

Figure 2B illustrates a section of road viewed in cross-section from the end of the road, with intact lane-marking lines on the road and a reference object associated with the road.

Figure 3A illustrates a section of road viewed from above, with partly covered lane-marking lines on the road, a reference object associated with the road, and a vehicle according to one embodiment. Figure 3B illustrates a section of road viewed in cross-section from the end of the road, with partly covered lane-marking lines on the road, a reference object associated with the road, and a vehicle according to one embodiment.

Figure 4A illustrates a section of road viewed from the perspective of a driver inside the vehicle according to one embodiment, wherein the section of road has at least partly covered lane-marking lines on the road and a reference object associated with the road.

Figure 4B illustrates an enlargement of a display screen in the vehicle according to one embodiment, on which screen the driver can view the po- sition of the vehicle in relation to lane-marking lines on the road.

Figure 5 shows a flow diagram that illustrates one embodiment of the invention.

Figure 6 is an illustration of a calculating unit according to one embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

The invention is defined as a method and a calculating unit for determining the lane position of the vehicle on a road, which can be realized in any of the embodiments described below. This invention can, however, be realized in many different forms, and is not to be viewed as being limited by the embodiments described herein, which rather are intended to elucidate and clarify various aspects of the invention.

Additional aspects and features of the invention can be derived from the following detailed description when it is considered in combination with the accompany fig- ures. However, the figures are to be viewed only as examples of different embodiments of the invention, and are not to be viewed as being limitative for the invention, which is limited rather solely by the accompanying claims. Furthermore, the figures are not necessarily drawn to scale and, unless otherwise specifically stated, are intended to illustrate aspects of the invention conceptually. Figure 1 shows a vehicle 100 in a direction of travel 105. This direction of travel 105 refers to an existing or planned direction of travel 105, i.e. the vehicle 100 can be in motion in the direction of travel 105, or be stationary, prepared for a planned movement in the direction of travel 105.

The vehicle 100 contains a calculating unit 110 and a sensor 120. The calculating unit 110 is arranged so as to determine the lane position of the vehicle on a road 130 based on information detected by the sensor 120 and conveyed to the calculating unit 110.

The sensor 120 can be mounted in or on the vehicle 100, e.g. in or on the vehicle cab. The sensor 120 can comprise or consist of, for example, a 3D camera, a Time-of-Flight camera (ToF camera), a stereo camera, a light-field camera, a camera, a radar measuring device, a laser measuring device such as a Light Detection And Ranging (LIDAR), sometimes also referred to as LADAR or laser-radar, or a similar device configured for distance determination. A LIDAR is an optical measuring instrument that measures properties of reflected light in order to determine the distance to and/or other properties of remote objects. The technology is reminiscent of radar (Radio Detection and Ranging), but light is used instead of radio waves. The distance to an object is typically meas- ured by measuring the time delay between an emitted laser pulse and the recorded reflection from the object.

A ToF camera is a type of camera that takes a sequence of pictures and measures a distance to an object based on the known speed of light, by measuring the amount of time it takes for a light signal to pass between the camera and the object, e.g. by measuring the phase shift between the emitted light signal and a received reflection of said light signal from the object.

In certain embodiments, more than one sensor 120 can be mounted on the vehicle 100. One advantage of having more than two sensors 120 is that more reliable distance determinations can be made, and a larger area can be monitored by an additional sensor. In such embodiments with more than one sensor 120, said sensor 120 can consist of the same type of sensor or of different types of sensors according to different embodiments.

As noted above, the vehicle 100 also contains a calculating unit 110, which is arranged so as to receive measurement data from the sensor 120, and to perform calculations based on these measurement data. For example, a distance from the vehicle 100 to lane markings on the road, and/or other reference objects associated with the road 130, can be measured by the sensor 120 and sent to the calculating unit 110, which can compare the measured value to lane-related data for the relevant section of road, and thereby determine where the lane markings of the road are, and determine whether the vehicle 100 is crossing said lane markings.

With the help of a cartographic database and a determined geographical position, e.g. a GPS position, it is possible to identify how many lanes the relevant road 130 has. If the sensor 120 succeeds in detecting one or a plurality of lane markings or another reference object in proximity to the road 130, a model of the relevant stretch of road can be used to estimate where other lane-marking lines should be. The sensor 120 can also be arranged so as to detect distances to reference objects such as objects that appear, such as a median barrier, a road sign, a wall, a building, a tree or the like, thereby making it possible to place the modeled lane- marking lines at correct distances, using the detected objects as a reference. According to certain embodiments, this thus provides greater access to the warning function for lane departures in situations in which the function is most needed, i.e. in connection with poor visibility and deficient road conditions. According to certain embodiments, the number of false warnings is also reduced, as false lines can be filtered out and rejected by the method, e.g. when the distance between two detected lines is unreasonable based on information from cartographic data.

In a case involving a slushy roadway 130 with asphalt exposed in the tire tracks, measurement points will likely be absent where the asphalt is exposed. If nothing else, the exposure for the sensor 120 can be calibrated so that this occurs, and it is then possible to use an IR-based sensor 120 as an asphalt detector on a snow- covered road, or as a tire track detector, in order to obtain an indirect understanding of the roadway, or a sensor 120 that will indicate whether there really are lines present or something else, according to different embodiments.

Figure 2A shows a geographical position 140 of the road 130 with a plurality of intact lane-marking lines 150, a median barrier 160 and a ditch 170 at the side of the road 130, viewed from a bird's-eye perspective. These characteristics of the road 130, i.e. lane-marking lines 150, the median barrier 160 and the ditch 170 can be designated as reference objects 150, 160, 170 associated with the road 130.

Figure 2B shows the same geographical position as is illustrated in Figure 2A, but viewed in cross-section from the end of the section of road.

Figure 3A shows a section of road 130 where certain lane-marking lines 150 are covered by, e.g. snow, sand or the like, or are difficult to discern due to wear or inadequate maintenance. Here we also see an embodiment of the vehicle 100 with the sensor 120, which detects certain reference objects 150, 160, 170 associated with the road 130 (see broken lines).

For example, the sensor 120 in this example can succeed in detecting and deter- mining a distance from the vehicle 100 to a road barrier 160, a distance from the vehicle to a lane-marking line 150 that the sensor 120 succeeds in detecting, and a roadside ditch or snow bank 170. Based on these measurements, a mapping and matching process can be carried out with corresponding reference objects 150, 160, 170 at the relevant geographical position based on cartographic data extracted from a cartographic database. For example, virtual lane-marking lines 150 can thus be displayed or clarified for the driver of the vehicle 100 according to certain embodiments, e.g. on a display screen in the vehicle 100, projected on the vehicle windshield, on the eyeglasses of the driver, or the like.

In this example the sensor 120 detects three reference objects 150, 160, 170 re- lated to the road 130. This is to be viewed solely as a non-limitative example that is not necessary per se in order to unambiguously determine the vehicle position in relation to the lane-marking lines 150 on the road 130. For example, more than three reference objects can be detected for more reliable positioning, or fewer reference objects, i.e. two or one, when the conditions do not enable the detection of more than, for example, one reference object.

Figure 3B shows the same section of road as is illustrated in Figure 3A, but viewed in cross-section from the end of the road.

Figure 4A illustrates a section of road viewed from the perspective of a driver inside the vehicle 100 according to one embodiment, wherein the section of road has at least partly covered lane-marking lines 150 on the road 130 and reference objects 150, 160, 170 associated with the road 130. In this embodiment, the calculating unit 110 can comprise a display screen 115, or be connected thereto. In such an embodiment, the driver can thus, on said display screen 115, see a depiction of his vehicle 100 in relation to lane-marking lines 150 on the road 130 along the relevant section of road. A non-limitative example of the latter is shown in Figure 4B, which illustrates an enlargement of the display screen 115 in the vehicle 100 according to one embodiment, in which the driver can see the position of the vehicle in relation to lane- marking lines 150 on the road 130. Figure 5 illustrates an exemplary embodiment of the invention. The flow diagram in Figure 5 clarifies a method 500 in a calculating unit 110 in a vehicle 100 for determining the lane position of the vehicle 100 on a road 130.

According to certain embodiments, the method is performed only when the lane- marking line 150 on the road 130 is concealed, when the weather conditions cause the sensor 120 to have limited range and/or when the road surface gives rise to an erroneous detection 502 of the lane-marking line 150. If the sensor 120 can be confirmed to be detecting all the lane-marking lines 150 on the road 130 without needing to compare them with collected data in a database, then this step can be skipped, thereby saving processor capacity and time. The major advantage with the method 500 first becomes evident under the opposite conditions, i.e. when the road 130 is concealed, when the weather conditions cause the sensor 120 to have a limited range and/or the road surface gives rise to an erroneous detection 502 of the lane-marking line 150, as the method 500 is intended to eliminate or at least reduce such deficiencies. The method 500 can comprise a number of steps 501-507 in order to enable the determination of the lane position on the road 130 in a correct manner. However, it should be noted that certain of the described steps 501-507 can be performed in a chronological order that differs somewhat from that indicated by their numerical order, and that certain of them can be performed in parallel with one another, ac- cording to different embodiments. Furthermore, certain of the described steps 501- 507 are performed only in certain embodiments, such as 503, 506 and/or 507. The method 500 comprises the following steps:

Step 501 The geographical position 140 of the vehicle is determined. Such a determination of the current geographical position 140 of the vehicle can be based on a satellite- based positioning system such as Global Positioning System (GPS), triangulation using signals emitted from base stations in a mobile telephone network with 5 known positions, travel route data, trip meter data in combination with a road number, a wireless sensor signal and/or manual input by, for example, the vehicle driver.

Step 502

A reference object 150, 160, 170 associated with the road 130 is detected by the 10 sensor 120.

In certain embodiments, the reference object 150, 160, 170 associated with the road 130 can consist of a lane-marking line 150 on the road 130.

However, in certain embodiments the reference object 150, 160, 170 can consist of an object 160, 170 located in proximity to the road, such as a median barrier 15 160, a ditch 170, a road sign, a building, an exit ramp, a wall, a light pole or the like.

According to various embodiments, the sensor 120 can consist, for example, of a camera, a 3D camera, a Time of Flight camera, a stereo camera, a light-field camera, a radar measuring device, a laser measuring device, a LIDAR, a distance 20 measuring device based on ultrasonic waves. According to various embodiments, the sensor 120 can further be arranged for communication with the calculating unit 110 over a wireless or wire-bound interface.

Step 503

This method step is performed in some, but not necessarily all embodiments of the 25 method 500.

A distance to the reference object 150, 160, 170 is measured at the determined 501 geographical position 140 by means of the sensor 120. Step 504

A comparison is made between lane-related data for the determined 501 geographical position 140 stored in a cartographic database and the detected 502 reference object 150, 160, 170 at said geographical position 140. Step 505

The lane position of the vehicle 100 is determined by matching the detected 502 reference object 150, 160, 170 associated with the road 130 with stored lane- related data for the determined 501 geographical position 140 of the vehicle 100.

In certain embodiments, the determination of the lane position of the vehicle 100 by means of matching the detected 502 reference object 150, 160, 170 can comprise the determination of an erroneous detection 502 of a lane-marking line 150 on the road 130, and the ignoring of said erroneous detection 502 when determining 505 the lane position. Such determination of an erroneous detection 502 of a lane-marking line 150 can include confirming that the distances between the de- tected 502 lane-marking line 150 and existing lane markings according to cartographic data for the geographical position 140 do not agree, or that the numbers of detected 502 and existing lane-marking lines 150 do not agree.

Step 506

This method step is performed in some, but not necessarily all embodiments of the method.

A warning signal is generated when the vehicle 100 is determined 505 to have crossed a lane-marking line 150 on the road 130.

Step 507

This method step is performed in some, but not necessarily all embodiments of the method 500. According to certain embodiments, a lateral position correction can be generated if the vehicle 100 is determined 505 to be crossing a lane-marking line 150 on the road 130.

Figure 6 shows an embodiment of a system 600 arranged so as to determine a lane position of a vehicle 100 on a road 130. The system 600 comprises at least one sensor 120, a cartographic database 640 and a calculating unit 110, which are arranged so as to communicate with one another over a wire-bound or wireless interface. The system 600 can also include a positioning unit 650 arranged so as to determine the geographical position of the vehicle 100. The positioning unit 650 can consist, for example, of a GPS receiver or other satellite-based unit arranged for positioning determination.

According to various embodiments, the wireless interface can be based, for example, one of the following technologies: Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Code Division Access (CDMA), (CDMA 2000), Time Division Synchronous CDMA (TD-SCDMA), Long Term Evolution (LTE); Wireless Fidelity (Wi-Fi), defined by the Institute of Electrical and Electronics Engineers (IEEE) standards 802.11 a, ac, b, g and/or n, Internet Protocol (IP), Bluetooth and/or Near Field Communication, (NFC), or a similar communication technology.

According to certain other embodiments, the calculating unit 110, the database 640 and the sensor 120 are arranged for communication and information transfer over a wire-bound interface. Such a wire-bound interface can comprise a communication bus system consisting of one or a plurality of communication buses for linking together a number of electronic control units (ECUs), or control units/controllers, and various components and sensors located on the vehicle 100. The vehicle communication bus can consist, for example, of one or a plurality of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Oriented Systems Transport), or some other bus configuration; or of a wireless connection, e.g. according to any of the foregoing technologies for wireless communication. In various embodiments, the sensor 120 in the vehicle 100 can consist of, for example, a camera, a 3D camera, a Time of Flight-camera, a stereo camera, a light- field camera, a radar measuring device, a laser measuring device, a LIDAR and/or a distance measuring device based on ultrasonic waves. The calculating unit 110 is arranged so as to perform at least parts of the method 500 in order to determine the lane position of the vehicle on a road 130.

To be able to determine the lane position of the vehicle correctly, the calculating unit 110 comprises a number of components, which are described in detail in the following text. Some of the described secondary components appear in some but not necessary all embodiments. Additional electronics can also be present in the calculating unit 110 that are not entirely necessary for understanding the function of the calculating unit 110 and the method 500 according to the invention.

The calculating unit 110 comprises a signal receiver 610 arranged so as to receive a signal from the sensor 120 contained in the vehicle 100, wherein the signal rep- resents a detected reference object 150, 160, 170 associated with the road 130. The signal receiver 610 typically contains a receiving circuit arranged so as to receive a wireless or wire-bound signal from the sensor 120, e.g. by means of one of the communication interfaces enumerated above.

Furthermore, the calculating unit 110 also contains a processor circuit 620 ar- ranged so as to determine the geographical position 140 of the vehicle 100, and also arranged so as to compare stored lane-related data for the determined geographical position 140 to a detected reference object 150, 160, 170 at said geographical position 140. Lane-related data can be stored and retrieved from a cartographic database 640, which can be contained in the calculating unit 110, or consist of an external unit with which the calculating unit 110 can communicate, e.g. over a wireless interface. Furthermore, the processor circuit 620 is arranged to determine the lane position of the vehicle 100 by matching the detected reference object 150, 160, 170 with stored lane-related data for the geographical position 140 for the vehicle 100. The processor circuit 620 can also be arranged so as to measure a distance to the reference object 150, 160, 170 at the determined geographical position 140, based on a signal received from a sensor 120 in the vehicle 100.

In certain embodiments, the processor circuit 620 can also be arranged so as to determine an erroneous detection of a lane-marking line 150 on the road 130, and to ignore such an erroneous detection in determining the lane position.

The processor circuit 620 can consist, for example, of one or a plurality of a Central Processing Unit (CPU), microprocessor or other logic designed so as to interpret and carry out instructions and/or read and write data. The processor circuit 620 can manage data for inflows, outflows or data-processing of data, including buffering of data, control function and the like.

In certain embodiments, the calculating unit 110 can also comprise a signal transmitter 630 arranged so as to send a control signal to trigger a warning signal and/or lateral position correction when the vehicle 100 is determined to be cross- ing a lane marking 150 on the road 130. In certain embodiments, the signal transmitter 630 can be arranged so as to send a control signal to prevent acceleration of the vehicle 100 and/or to initiate braking of the vehicle 100.

According to certain embodiments, the calculating unit 110 can also contain a memory unit 625 which can, in certain embodiments, consist of a storage medium for data. The memory unit 625 can consist, for example, of a memory card, flash memory, USD memory, hard disk or other similar data-storage unit, such as any of the group comprising ROM (Read-Only Memory), PROM (Programmable Readonly Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), etc in various embodiments. The aforementioned cartographic database 640 can be contained in or connecta- ble to the calculating unit 110. For example, the cartographic database 640 can comprise a USB memory containing cartographic data. Cartographic data can, for example, be downloaded or updated via an Internet connection in certain embodiments, or by means of another similar uplink. However, in certain embodiments the cartographic database 640 can be disposed outside the vehicle 100 and be accessible for the calculating unit 110 by means of a wireless interface, e.g. one of those enumerated above.

This cartographic database 640 can be built up in that, e.g. certain reference vehi- cles will drive stretches of road under favorable weather and road conditions and record and store road data associated with geographical positions.

Furthermore, the invention according to certain embodiments contains a computer program for determining the lane position of a vehicle 100 on a road 130.

The computer program is arranged so as to perform the method 500 according to at least one of the aforedescribed steps 501-507 when the program is executed in a processor circuit 620 in the calculating 110.

The method 500 can thus, according at least one of the steps 501-507 for determining the lane position of the vehicle on the road 130, be implemented by means of one or a plurality of processor circuits 620 in the calculating unit together with computer program code for performing one, several, certain or all of the steps 501-507 described above. A computer program containing instructions for performing the steps 501-507 when the program is loaded into the processor circuit 620 can thereby be [sic].

In certain embodiments, the aforedescribed computer program in the vehicle 100 is arranged so as to be installed in the memory unit 625 in the calculating unit 110, e.g. over a wireless interface.

The signal receiver and/or signal transmitter described and discussed above can, in certain embodiments, consist of separate transmitters and receivers. However, in certain embodiments the signal receiver 610 and signal transmitter 630 in the calculating unit 110 can consist of a transceiver that is adapted to transmit and receive radio signals, wherein parts of the design, such as the antenna, are common to both transmitter and receiver. Said communication can be adapted for wireless information transfer via radio waves, WLAN, Bluetooth or an infrared transceiver module. However, in certain embodiments the signal receiver 610 and/or signal transmitter can alternatively be specially adapted for wire-bound information exchange, or alternatively for both wireless and wire-bound communication according to some embodiments.

All embodiments of the invention also include a vehicle 100, which contains a sys- tern 600 installed in the vehicle and arranged so as to perform a method 500 according to at least one of the method steps 501-507 for determining the lane position of the vehicle 100 on a road 130.