WO2020046187A1

WO2020046187A1 - Method and control arrangement for calculating an appropriate vehicle speed

Info

Publication number: WO2020046187A1
Application number: PCT/SE2019/050750
Authority: WO
Inventors: Jonny Johansson; Jimmy Nichols; Andreas HÖGLUND
Original assignee: Scania Cv Ab
Priority date: 2018-08-30
Filing date: 2019-08-16
Publication date: 2020-03-05
Also published as: SE1851025A1

Abstract

Method (500) and control arrangement (300) in a vehicle (100), for calculating an appropriate vehicle speed of the vehicle (100). The method (500) comprises detecting (501) a traffic light (120) ahead of the vehicle (100); determining (502) a distance between the vehicle (100) and the detected (501) traffic light (120); acquiring (503) information concerning remaining time to next phase shift of the detected (501) traffic light (120); determining (504) speed limitation on a road segment between the current vehicle position and the traffic light (120); calculating (505) the appropriate vehicle speed in order to pass the traffic light (120) during a green period, without having to stop; and outputting (508) information concerning the appropriate vehicle speed when said speed is within a predefined first threshold from the calculated (505) speed limitation.

Description

METHOD AND CONTROL ARRANGEMENT FOR CALCULATING AN APPROPRIATE VEHICLE SPEED

TECHNICAL FIELD

This document discloses a method and a control arrangement. More particularly, a method and a control arrangement are described, for calculating an appropriate vehicle speed of the vehicle.

BACKGROUND

More and more traffic signals around the world are connected to a central server. This gives the possibility to send information to the vehicles, around the traffic signal, for example con cerning when the light is going to turn from red to green. This information may in turn be used by the vehicle and / or vehicle driver who, by having knowledge of the remaining time period in green, before a phase shift to red (or alternatively until a phase shift from red into green) adapt the vehicle speed, in order to avoid having to stop at the traffic signal.

A problem with these calculations is that the outcome is not related to the traffic situation, and / or the allowed traffic speed. For example, the recommended vehicle speed might be significantly slower than the speed limit, i.e. it might not be wise to drive at 40 km/h when the speed limit is 70 km/h, as it may cause frustration for other road users, and / or cause acci dents due to inappropriate overtaking.

Also, the vehicle may pass several intersections, each regulated by a traffic light which may be uncorrelated with the other close-by traffic lights. Thereby, it would be desired to adapt the vehicle speed for passing a sequence of traffic lights in the green phase. However, it may be difficult to predict which route the vehicle is going to drive.

Yet a problem in complex traffic situations at an intersection is that there may be several traffic signals within close range, which are controlling the traffic going in different directions. It is then difficult to determine which traffic signal that is relevant for the vehicle. In case information is obtained from another traffic signal, not controlling the traffic of the traffic lane or direction of the vehicle, the driver may become confused, or may start driving in belief that the traffic signal has switched into green while it in fact is red.

Document GB2452835 describes a method for adjusting the cruise control set-point auto matically and updating it cyclically depending on data received from a traffic light. The document does not describe an adaptive cruise control and neither the requirement for the driver to acknowledge a speed increase.

Document US8478500 describes a method for automatically and dynamically adjusting the cruise control of a vehicle based on traffic light position and schedule. The determined dis tance and speed of the preceding vehicle is used as a constraint for the calculated velocity profile.

However, the document does not take environmental traffic situation in other possible ways into account, or to the speed limit of the road segment.

Document US20140046581 describes a device and method for calculating a recommended speed based on information received about the next traffic light’s position, schedule and the estimated number of waiting vehicles.

The main focus of the document is describing the method of producing the recommended speed. The driver of the vehicle is notified; no adjustment or adaptation of the output recom mended speed is made to the environmental traffic situation, besides counting the number of waiting vehicles at the traffic light.

Document US201 1098898 shows an adaptive cruise control that uses timing information from a traffic light.

The driver can be informed if the traffic light can be passed using an increased speed, but no acknowledgement is needed. The solution disclosed in the document does not discuss the adequacy of the recommended speed.

It would be desirable to find a solution to the above described problems, to estimate an ap propriate speed for arriving at a traffic light during a green period of the traffic light, taking the environmental traffic situation into account.

SUMMARY

It is therefore an object of this invention to solve at least some of the above problems and improve traffic flow by providing information to a vehicle.

According to a first aspect of the invention, this objective is achieved by a method of a control arrangement in a vehicle, for calculating an appropriate vehicle speed of the vehicle. The method comprises detecting a traffic light ahead of the vehicle. Further, the method also comprises determining a distance between the vehicle and the detected traffic light. The method furthermore comprises acquiring information concerning remaining time to next phase shift of the detected traffic light. Also, the method in addition comprises determining speed limitation on a road segment between the current vehicle position and the traffic light. The method also, in further addition comprises calculating the appropriate vehicle speed in order to pass the traffic light during a green period, without having to stop. The method com prises outputting information concerning the appropriate vehicle speed when said speed is within a predefined first threshold from the calculated speed limitation.

According to a second aspect of the invention, this objective is achieved by a control ar rangement in a vehicle, for calculating an appropriate vehicle speed of the vehicle. Further, the control arrangement is configured to detect a traffic light ahead of the vehicle via a sen sor. In addition, the control arrangement is configured to determine a distance between the vehicle and the detected traffic light. The control arrangement is also configured to acquire information concerning remaining time to next phase shift of the detected traffic light, via a communication device. In further addition, the control arrangement is configured to deter mine speed limitation on a road segment between the current vehicle position and the traffic light. The control arrangement is furthermore, also configured to calculate the appropriate vehicle speed in order to pass the traffic light during a green period, without having to stop. The control arrangement is configured to output information, on a display, concerning the appropriate vehicle speed when said speed is within a predefined first threshold from the calculated speed limitation.

Thanks to the described aspects, by calculating an appropriate speed for the vehicle to keep for arriving at the traffic light during a green period, but only output information concerning the appropriate speed when it is suitable, in the current traffic situation, it is avoided that the driver is recommended to drive in a speed which is considerably lower than the current speed limitation. It is thereby avoided to output a speed recommendation that is inappropriate or disturbing for other road users. Thereby, traffic security is enhanced, while the vehicle is enabled to pass the traffic light during a green period, without having to stop which saves fuel.

Other advantages and additional novel features will become apparent from the subsequent detailed description. FIGURES

Embodiments of the invention will now be described in further detail with reference to the accompanying figures, in which:

Figure 1 illustrates an example of a vehicle equipped with an embodiment of the inven- tion, approaching a road intersection;

Figure 2 illustrates an example of a vehicle equipped with an embodiment of the inven tion, approaching a road intersection as regarded from above;

Figure 3 illustrates an example of a vehicle equipped with an embodiment of the inven tion, as regarded from within the vehicle when approaching a road intersec tion;

Figure 4 illustrates an example of a vehicle approaching a road intersection as re garded from above, according to an embodiment;

Figure 5 is a flow chart illustrating an embodiment of the method;

Figure 6 is an illustration depicting a system according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention described herein are defined as a method, a control arrange ment and a system, which may be put into practice in the embodiments described below. These embodiments may, however, be exemplified and realised in many different forms and are not to be limited to the examples set forth herein; rather, these illustrative examples of embodiments are provided so that this disclosure will be thorough and complete.

Still other objects and features may become apparent from the following detailed description, considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the herein disclosed embodiments, for which reference is to be made to the appended claims. Further, the drawings are not necessarily drawn to scale and, unless oth erwise indicated, they are merely intended to conceptually illustrate the structures and pro cedures described herein.

Figure 1 illustrates a scenario with a vehicle 100 driving in a driving direction 105 on a road 110a, approaching a road intersection where a traffic light 120 is situated in order to regulate the traffic. The vehicle 100 may comprise a means for transportation in broad sense such as e.g. a truck, a car, a motorcycle, a trailer, a bus, a bike, a train, a tram, an aircraft, a watercraft, an unmanned underwater vehicle/ underwater drone, a cable transport, an aerial tramway, a drone, a humanoid service robot, a spacecraft, or other similar manned or unmanned means of conveyance running e.g. on wheels, on rails, in air, in/on water, in space, etc.

The vehicle 100 may be driver controlled or driverless (i.e. autonomously controlled) in dif ferent embodiments. However, for enhanced clarity, the vehicle 100 is subsequently de scribed as having a driver.

The traffic light 120 may comprise, or be associated with, a transmitter 130. The traffic light 120 may be connected to a central server in some embodiments, possibly together with a number of other traffic lights, situated in the same or other crossings.

The vehicle 100 may comprise a communication device 140, configured for wireless com munication with the transmitter 130 associated with the traffic light 120. Thereby, communi cation may be made between the traffic light 120 and the vehicle 100, such as for example the remaining time until the traffic light 120 turns from red to green; or how much time remains until the traffic light 120 turns from green to red, for example.

Communication between the transmitter 130 and the communication device 140 may be made over a wireless communication interface, such as e.g. Vehicle-to-Vehicle (V2V) com munication, or Vehicle-to-lnfrastructure (V2I) communication. The common term Vehicle-to- Everything (V2X) is sometimes used. The communication may e.g. be based on Dedicated Short-Range Communications (DSRC) devices. DSRC works in 5.9 GHz band with band width of 75 MHz and approximate range of 1000 m in some embodiments.

The wireless communication may be made according to any IEEE standard for wireless ve hicular communication like e.g. a special mode of operation of IEEE 802.1 1 for vehicular networks called Wireless Access in Vehicular Environments (WAVE). IEEE 802.1 1 p is an extension to 802.1 1 Wireless LAN medium access layer (MAC) and physical layer (PHY) specification.

Such wireless communication interface may comprise, or at least be inspired by wireless communication technology such as Wi-Fi, Wireless Local Area Network (WLAN), Ultra Mo bile Broadband (UMB), Bluetooth (BT), Radio-Frequency Identification (RFID), etc.

The communication may alternatively be made over a wireless interface comprising, or at least being inspired by radio access technologies such as e.g. 3GPP LTE, LTE-Advanced, E-UTRAN, UMTS, GSM, GSM/ EDGE, WCDMA, Time Division Multiple Access (TDMA) net works, or similar, just to mention some few options, via a wireless communication network.

However, the intersection may have several independent traffic lights 120 that could apply to the vehicle 100. In order to give the driver (if any) correct information, it is also important to know in which direction the vehicle 100 is heading, i.e. going straight ahead or turn left/ right. In many cases it may also be an advantage to be able to consider multiple intersections ahead of the vehicle 100, in the future driving direction of the vehicle 100, in order to give better speed recommendations to the vehicle 100/ driver or provide an improved estimation of time of arrival.

In order to determine which way the vehicle 100 is going to drive, for example by extracting navigation information from a navigator of the vehicle 100; by determining position of the vehicle 100 and determine which driving lane the vehicle 100 is situated in; and / or based on sensor information, detecting e.g. arrows on the driving lane and / or the traffic light 120, or the driving direction of the in front vehicle, for example.

Thus, the vehicle 100 may comprise a sensor 145 in some embodiments, in order to detect the future driving direction of the vehicle 100, detect environmental traffic situation, and / or the traffic light 120.

The sensor 145 may be forwardly directed in the driving direction 105 of the vehicle 100. In the illustrated embodiment, which is merely an arbitrary example, the forwardly directed sen sor 145 may be situated e.g. at the front of the vehicle 100, behind the windscreen of the vehicle 100.

The sensor 145 may comprise e.g. a camera, a stereo camera, an infrared camera, a video camera, a radar, a lidar, an ultrasound device, a time-of-flight camera, or similar device, in different embodiments. The sensor 145 may be dedicated to detect driving lane direction, e.g. by detecting a driving direction arrow painted on the driving lane; however, the sensor 145 may also or alternatively be used for a variety of other tasks.

The sensor 145 comprises, or may be connected to a control arrangement configured for image recognition/ computer vision and object recognition. Thereby the process of detecting driving intention of the driver may be automated. The image understanding can be seen as the disentangling of symbolic information from image data using models constructed with the aid of geometry, physics, statistics, and learning theory.

The image data of the sensor 145 may take many forms, such as e.g. images, video se quences, views from multiple cameras, or multi-dimensional data from a scanner.

The driving direction may comprise one or several algorithms that can be used independently or in a combination with each other, depending on the traffic situation. These algorithms can also be used with other algorithms that are not stated here.

Using a camera, other sensor or such as high precision positioning and a map to detect what lane that the vehicle is travelling in. Comparing the information from the camera/ sensor 145 with information regarding the lanes leading to the traffic light 120 in order to see what traffic light 120 that the lane is related to. The closer the vehicle 100 gets to the traffic light 120, the higher the probability that the current lane is indicating what direction the vehicle 100 will have through the traffic light 120. To increase the confidence in the prediction, the type of lines that separate the lanes can be detected and used. If the line between the lanes indi cates that it is not allowed to change lane, it is very likely that the direction of the current lane is the direction that the vehicle 100 will have when passing the traffic light 120.

A type of route that the vehicle 100 intends to follow may be extracted, for example from a navigation function of the vehicle 100, to detect which direction that the navigator will recom mend. This information may also be verified by comparing the suggested driving direction with the detected driving lane wherein the vehicle 100 is situated.

Further, information about the current traffic situation may be obtained, for example local hazard/ road works warnings which are distributed by various traffic services. It may thereby, by also determining the geographical position of the vehicle 100, be determine whether the vehicle 100 is approaching a road section where at least one of the lanes are partly or com pletely blocked e.g., by a road work, an accident, etc. In this case, i.e. when the lane which the vehicle 100 currently is determined to be situated within, or a parallel lane, the confidence of the prediction may be considered low, and the direction prediction may be paused until the vehicle 100 has passed the local hazard to see if the vehicle 100 changes lanes or not. The obtained information may also be verified by comparing the suggested direction with the detected lane according to the determination of the vehicle position performed by the navi gator. The geographical position of the vehicle 100 may be determined, and it may be detected using map data of the determined geographical position if any of the lanes has a restricted use, for example a bus lane. This may also be combined with any type of map-data to in crease the confidence in the information. If the vehicle 100 is a travelling in a restricted lane and is allowed to do so, for example when the vehicle 100 is a bus, taxi, emergency vehicle etc., it may be seen as probable that the vehicle 100 will follow the direction of that lane. If the vehicle 100 is not allowed to travel in the restricted lane, a check may be made to deter mine if the lane ends before the traffic lights 120. If it does not, it is likely not to be used and can be discharged from the prediction, if it does end, it cannot be discharged as a possible lane to be used.

Further, the direction indicator may be used to determine the intention of the driver of the vehicle 100. All or some of these different aspects may be combined in order to make an improved prediction of the intended driving direction.

Based on the information of the ahead traffic light 120, i.e. concerning green period of the traffic light 120 such as remaining time to the next phase shift, local speed limitation, and / or speed of the traffic surrounding the vehicle 100, an appropriate vehicle speed may be calcu lated for arriving to the traffic light 120 during a green period thereof, without having to stop.

The calculated recommended vehicle speed may be displayed if at least one of these two conditions are fulfilled: The recommended vehicle speed is within a predefined first threshold from the current speed limit; or the vehicle speed/ surrounding vehicles speed is within a predefined second threshold from the recommended vehicle speed.

By determining the local speed limitation and consider the local speed limitation before out- putting a speed recommendation to the vehicle 100 is that firstly it could be avoided that the vehicle 100 is recommended to overspeed, secondly it is avoided that the vehicle 100 is recommended a speed which is so low that it is likely to annoy/ confuse other traffic users, which may trigger vicious overtaking, etc. Thereby, only recommended speeds between the maximum local speed limitation and a lower speed threshold, such as e.g. about 10% lower, 20% lower, 30% lower, etc. may be allowed to be output to the driver.

Further, in some embodiments, recalculations may be made continuously, or at certain time intervals. The recommended vehicle speed may be the set speed of the cruise control and if the recommended speed is adjusted (due to changes in the environmental traffic situation) the cruise control speed may be adjusted accordingly. Hence changing traffic situations may be handled automatically with the function.

Thereby, in case of a traffic congestion or dense traffic, or otherwise reduced speed among the surrounding vehicles, e.g. due to low visibility, animals at or close to the lane, children playing close to the street, etc., a recalculation may be made and the recommended speed (when lower than the lower speed threshold) may be output to the vehicle 100. The vehicle 100 may then anyway adapt the driving speed to avoid having to stop at the traffic light 120.

However automatically adjusting the set speed to a higher value without having an adaptive cruise control that can adjust the vehicle speed if there is a vehicle in front might lead to an unwanted behavior of the vehicle. This can be solved by notifying the driver that a change in set-speed is needed and only adjust the set speed if the driver acknowledges the change. Thereby an accident may be avoided.

Figure 2 illustrates a scenario wherein the vehicle 100 is approaching an intersection where different lanes 1 10a, 1 10b, 1 10c are dedicated for different directions after the intersection. In this particular illustrated intersection, one lane 1 10a is dedicated for right turn, one lane 1 10b is dedicated for driving straight ahead, while one driving lane 1 10c is dedicated for turning left.

The driving lanes 1 10a, 1 10b, 1 10c may be divided by road markings 250a, 250b. One first road marking 250a between two of the lanes 1 10a, 1 10b while one second road marking 250b is situated the two other lanes 1 10b, 1 10c.

In this intersection, one traffic light 120 may be dedicated for the driving lane 1 10a for right turn, one other traffic light 220 may be dedicated for the driving lane 1 10b for driving straight ahead after the intersection, and one traffic light 240 may be dedicated for the driving lane 1 10c for turning left. These traffic lights 120, 220, 240 may be uncorrelated between each other in some embodiments, i.e. they may switch between different phases, such as typically red, amber/ yellow, and / or green. In other embodiments, at least some of the traffic lights 120, 220, 240 may be correlated with each other. Also, in some embodiments, one of the driving lanes 1 10a, 1 10b, 1 10c may be dedicated for a particular type of traffic or vehicle type, such as busses, taxis, emergency vehicles, etc. The traffic light 120, 220, 240 control ling the traffic of that driving lane 1 10a, 1 10b, 1 10c may have a different design, for make them easily distinguishable from those for normal/ private traffic. The traffic light 120, 220, 240 may comprise letters, text, arrows or bars of white or coloured light. Further, the traffic lights 120, 220, 240 may comprise or be associated with one or several transmitters/ transceivers 130, 210, 230. Thus, several traffic lights 120, 220, 240 may be associated with one, or several, transmitters/ transceivers 130, 210, 230 for communication with the close by vehicles 100.

In some embodiments, the traffic lights 120, 220, 240 may be connected to a central server via a wired or wireless connection. Thereby, information may be coordinated and / or com municated with the central server.

Information concerning the remaining time in the green period of the traffic lights 120, 220, 240, alternatively the remaining time in the red period before the traffic light 120, 220, 240 switches into green may be communicated to the close by vehicles 100.

However, it may be important to determine which traffic light 120, 220, 240 that is relevant for the vehicle 100, to provide the correct information concerning next phase shift of the relevant (for the vehicle 100) traffic light 120, 220, 240 when there are several uncorrelated traffic lights 120, 220, 240 close to each other.

In some embodiments, the geographical position of the vehicle 100 may be determined and by using a detailed map of the road, it may be determined which driving lane 1 10a, 1 10b, 1 10c the vehicle 100 is situated in. It may be presumed that the vehicle 100 is going to drive in the direction associated with the driving lane 1 10a, 1 10b, 1 10c in which the vehicle 100 currently is situated. The probability of the driving direction may be increased the shorter the distance is to the traffic light 120, 220, 240.

In some embodiments, or in combination with the determination of the geographical position, a sensor 145 of the vehicle 100, such as e.g. a camera, may detect a sign on the driving lane 1 10a, 1 10b, 1 10c, typically an arrow, which information may be used for predicting the future driving direction of the vehicle 100. Also, or alternatively, the sensor 145 may detect driving direction indications from road signs, or from an ahead vehicle for example.

Further, the direction indicator of the vehicle 100 may be used to determine the intention of the driver of the vehicle 100.

Figure 3 illustrates an example of how the previously scenario in Figure 1 , and / or possibly Figure 2 may be perceived by a driver (if any) of the vehicle 100, approaching an intersection and a traffic light 120.

The traffic light 120 may be detected by the sensor 145 in the vehicle 100 in some embodi ments. Further, or alternatively, the traffic light 120 may be detected by receiving wireless signals emitted by a transceiver 130 associated with the traffic light 120, received by the receiver 140 in the vehicle 100.

Further, the vehicle 100 comprises a control unit 300, configured for assisting the driver of the vehicle 100 in obtaining information from a traffic light 120 controlling traffic at an inter section. Information received wirelessly from the traffic light 120 may be output to the driver on a display 310. In the illustrated arbitrary example, a red-light countdown app is depicted.

Also, or alternatively, the information related to the traffic light 120 may be outputted to the driver, e.g. by a text message on a screen in the driver area in the vehicle 100, an acoustic message from a loudspeaker in the driver area of the vehicle 100, a haptic signal or tactile feedback in the steering wheel, driver seat or similar.

The geographical position of the vehicle 100 may be determined by a positioning unit 320 in the vehicle 100, which may be based on a satellite navigation system such as the Navigation Signal Timing and Ranging (Navstar) Global Positioning System (GPS), Differential GPS (DGPS), Galileo, GLONASS, or the like.

The geographical position of the positioning unit 320, (and thereby also of the vehicle 100) may be made continuously with a certain predetermined or configurable time intervals ac cording to various embodiments.

Positioning by satellite navigation is based on distance measurement using triangulation from a number of satellites 330a, 330b, 330c, 330d. In this example, four satellites 330a, 330b, 330c, 330d are depicted, but this is merely an example. More than four satellites 330a, 330b, 330c, 330d may be used for enhancing the precision, or for creating redundancy. The satellites 330a, 330b, 330c, 330d continuously transmit information about time and date (for example, in coded form), identity (which satellite 330a, 330b, 330c, 330d that broadcasts), status, and where the satellite 330a, 330b, 330c, 330d are situated at any given time. The GPS satellites 330a, 330b, 330c, 330d sends information encoded with different codes, for example, but not necessarily based on Code Division Multiple Access (CDMA). This allows information from an individual satellite 330a, 330b, 330c, 330d distinguished from the others' information, based on a unique code for each respective satellite 330a, 330b, 330c, 330d. This information can then be transmitted to be received by the appropriately adapted posi tioning device comprised in the vehicle 100.

Distance measurement can according to some embodiments comprise measuring the differ ence in the time it takes for each respective satellite signal transmitted by the respective satellites 330a, 330b, 330c, 330d to reach the positioning unit 320. As the radio signals travel at the speed of light, the distance to the respective satellite 330a, 330b, 330c, 330d may be computed by measuring the signal propagation time.

The positions of the satellites 330a, 330b, 330c, 330d are known, as they continuously are monitored by approximately 15-30 ground stations located mainly along and near the earth's equator. Thereby the geographical position, i.e. latitude and longitude, of the vehicle 100 may be calculated by determining the distance to at least three satellites 330a, 330b, 330c, 330d through triangulation. For determination of altitude, signals from four satellites 330a, 330b, 330c, 330d may be used according to some embodiments.

Having determined the geographical position of the positioning unit 320 (or in another way), the relevant driving lane 1 10a, 1 10b, 1 10c of the vehicle 100 may be determined when ap plying the determined geographical location of the vehicle 100 to a detailed map of the area, which may be comprised in a database 340 in the vehicle 100, or possibly outside the vehicle 100.

However, the position of the vehicle 100 may alternatively, or additionally be determined e.g. by having transponders positioned at known positions around the route and a dedicated sensor in the vehicle 100, for recognising the transponders and thereby determining the po sition; by detecting and recognising WiFi networks (WiFi networks along the route may be mapped with certain respective geographical positions in a database); by receiving a Blue tooth beaconing signal, associated with a geographical position, or other signal signatures of wireless signals such as e.g. by triangulation of signals emitted by a plurality of fixed base stations with known geographical positions.

The vehicle 100 may further comprise a navigator 325, in which the driver or other person may register the destination of the vehicle 100. In some embodiments, it may be presumed that the vehicle 100 is going to turn in the direction leading towards the destination of the navigator 325 when arriving at the intersection. Further, or alternatively, this information may be used in combination with other indications, e.g. driving lane 1 10a, 1 10b, 1 10c determina tion, for making a better prediction. Figure 4 illustrates an intersection 400 as regarded from above. The vehicle 100 is driving on a driving direction 105 on a driving lane 1 10 and is approaching the intersection 400 and the traffic light 120, regulating the traffic in at least one direction after the intersection. The intersection 400 may for example be a road junction, a roundabout, or similar.

In the illustrated scenario, the vehicle 100 is going to turn right after the intersection, but change driving lanes right before the intersection, from the right driving lane to the left driving lane. This behaviour may normally be indicative of the vehicle 100 is intending to turn left in the crossing 400.

However, in the illustrated example, the right driving lane is blocked by a road work (or any other arbitrary obstacle).

The road work may be detected by a vehicle external sensor 410, and the information con cerning the road work may be obtained from a traffic surveillance service 420. Also, or alter natively, the road work may be detected by the sensor 145 of the vehicle 100, and / or de tected by a sensor of another vehicle close-by and reported to the vehicle 100 via wireless communication. Information concerning the road work may also be prior notified and ob tained from a service provider.

When an obstacle such as a road work is detected in front of the vehicle 100 in the same driving lane, and the vehicle changes driving lanes, the driving lane position may be ne glected when predicting driving direction after the intersection 400, and determining the rel evant traffic light 120, 220, 240.

Figure 5 illustrates an example of a method 500 according to an embodiment. The flow chart in Figure 5 shows the method 500 for use in a vehicle 100 for calculating an appropriate vehicle speed of the vehicle 100 and assisting a driver of the vehicle 100 in obtaining infor mation related to a traffic light 120, controlling traffic at an intersection 400. The control ar rangement 300 may be configured for a cruise control functionality in some embodiments.

In order to correctly perform the speed calculations, the method 500 may comprise a number of steps 501-509. However, some of these steps 501 -509 may be performed in different alternative embodiments manners. Also, some of these steps 501 -509 may be performed solely in some alternative embodiments, like e.g. steps 506-507 and / or step 509. Further, the described steps 501 -509 may be performed in a somewhat different chronological order than the numbering suggests. The method 500 may comprise the subsequent steps:

Step 501 comprises detecting a traffic light 120 ahead of the vehicle 100.

The detection may be made in one out of several possible ways, such as for example by identifying the traffic light 120 with a forwardly directed sensor 145 on the vehicle 100, by extracting an identification of the traffic light 120 from a database in combination with deter mining vehicle position; and / or by receiving a wireless identity signal from the traffic light 120, etc. The traffic light 120 may also be detected by receiving a wireless signal emitted by a transmitter 130, associated with the traffic light 120, wherein the wireless signal may com prise an identity reference of the traffic light 120. Some of these and possibly some other methods may with advantage be combined, e.g. by using a plurality of different sensors, resulting in improved veracity.

Step 502 comprises determining a distance between the vehicle 100 and the detected 501 traffic light 120.

The distance may be determined based on geographical positioning of the vehicle 100 via a positioning device 320, based on satellite positioning such as GPS; and knowledge of the position of the traffic light 120, e.g. by obtaining an identity reference of the traffic light 120 and retrieve the position from a database.

The distance may alternatively be determined by a laser rangefinder or similar device in the vehicle 100. The laser rangefinder uses a laser beam to determine the distance to the traffic light 120. The laser rangefinder may operate on the time of flight principle by sending a laser pulse in a narrow beam towards the traffic light 120 and measuring the time taken by the pulse to be reflected off the traffic light 120 and returned to the vehicle 100.

Step 503 comprises acquiring information concerning remaining time to next phase shift of the detected 501 traffic light 120.

The information may be received via a wireless communication interface from the transceiver 130. The transceiver 130 may be comprised in or at the traffic light 120 in some embodi ments. However, the transceiver 130 may be co-located but independent from the traffic light 120 in some embodiments. In yet other embodiments, the transceiver 130 may be external to the traffic light 120. One transceiver 130 may serve a plurality of traffic lights 120, 220, 240 in some embodiments. Step 504 comprises determining speed limitation on a road segment between the current vehicle position and the traffic light 120.

The speed limitation may be extracted from a database 340 in some embodiments, compris ing detailed map data and wherein different speed limitations are associated with different geographical positions. By determining the current geographical position, the current speed limitation thus may be extracted. However, in other embodiments, the speed limitation may be detected by the sensor 145, e.g. by reading and interpreting the graphics on a road sign. The speed limitation may in yet some embodiments be obtained from the traffic light 120, via the received wireless signal.

In case the determining speed limitation is higher than the maximum allowed speed of the vehicle 100, the speed limitation may be replaced by the maximum allowed vehicle speed.

Step 505 comprises calculating the appropriate vehicle speed in order to pass the traffic light 120 during a green period, without having to stop at the traffic light 120.

The calculation is based on knowledge of the green period of the traffic light 120 and the distance between the vehicle 100 and the traffic light 120.

As the green period is a time interval, also the appropriate vehicle speed in fact may be regarded as an interval, i.e. a lower limit speed and an upper limit speed. In some embodi ments, an average speed may be computed.

Step 506, which may be performed only in some particular embodiments, comprises deter mining speed of an ahead vehicle 350.

The ahead vehicle speed may be determined by a sensor 135 in the vehicle 100. However, other methods may be used for determining the ahead vehicle speed, e.g. by using a vehicle external sensor, e.g. situated at the traffic light 120 or other road side structure and sending wireless information to the vehicle 100; or by obtaining speed information from a speedom eter of the ahead vehicle 350 via vehicle-to-vehicle communication.

Step 507, which may be performed only in some particular embodiments, comprises esti mating the traffic situation ahead of the vehicle 100, between the position of the vehicle 100 and the traffic light 120. The ahead traffic situation may be continuously estimated, and the appropriate vehicle speed may be recalculated when a change in the traffic situation is detected.

The traffic situation may for example be estimated based on information perceived from a traffic information service; and / or on sensor information of sensors in the vehicle 100, and / or vehicle external sensors. Another possibility may be to estimate the traffic situation by identifying cellular telephones, navigators and / or other communication equipment of drivers/ passengers of the vehicles between the vehicle 100 and the traffic light 120, and thereby estimating the number of vehicles and their speed.

Step 508 comprises outputting information concerning the appropriate vehicle speed when said speed is within a predefined first threshold from the calculated 505 speed limitation; i.e. lower than the calculated 505 speed limitation.

The predefined first threshold from the calculated 505 speed limitation may be e.g. 10% lower, 15% lower, 20% lower, etc. (non-limiting examples).

Thus, if the calculated appropriate vehicle speed is higher than the calculated 505 speed limitation, e.g. 50km/h, or lower than the predefined first threshold from the calculated 505 speed limitation, such as e.g. 40km/h, no information concerning the calculated appropriate vehicle speed is output to the driver during normal traffic conditions.

Thereby, it is avoided to output a vehicle speed recommendation, which is so low that it cannot be maintained without confusing/ irritating other traffic users, a behaviour which may cause an accident.

However, in an extraordinary traffic scenario, due to traffic congestion, accident, roadwork, icy road, low visibility etc., the environmental traffic may move in a considerably lower speed than the calculated 505 speed limitation. In such scenario, the information may be outputted 508 when the calculated appropriate vehicle speed is within a predefined second threshold from the determined 506 speed of the ahead vehicle 350.

The predefined second threshold may be e.g. 10% lower, 15% lower, 20% lower, etc. (non limiting examples). The output recommended speed may thereby be more reliable than according to prior art solution, wherein no adaptation is made to the environmental traffic situation.

The information concerning the appropriate vehicle speed may in some embodiments not be outputted when the estimated 507 traffic situation preclude arrival of the vehicle 100 to the traffic light 120 in a green period.

Step 509, which may be performed only in some particular embodiments wherein the control arrangement 300 is configured for a cruise control functionality, comprises adjusting the cruise control of the vehicle 100 to the appropriate vehicle speed when said speed is within the predefined first threshold from the determined 505 speed limitation, or when the appro priate vehicle speed is within the predefined second threshold from the determined 506 speed of the ahead vehicle 350.

Thereby, the speed of the vehicle 100 may be adapted for arriving at the traffic light 120 during a green period, without having to stop.

Figure 6 illustrates an embodiment of a system 600 for calculating an appropriate vehicle speed of the vehicle 100. The system 600 may perform at least some of the previously de scribed steps 501 -509 according to the method 500 described above and illustrated in Figure 5.

The system 600 may comprise a control arrangement 300 in the vehicle 100, for calculating an appropriate vehicle speed of the vehicle 100. The control arrangement 300 is configured to detect a traffic light 120 ahead of the vehicle 100. Further, the control arrangement 300 is configured to determine a distance between the vehicle 100 and the detected traffic light 120. Also, the control arrangement 300 is configured to acquire information concerning re maining time to next phase shift of the detected traffic light 120, via a communication device 140. The control arrangement 300 is furthermore configured to determine speed limitation on a road segment between the current vehicle position and the traffic light 120. The control arrangement 300 is also configured to calculate the appropriate vehicle speed in order to pass the traffic light 120 during a green period, without having to stop. The control arrange ment 300 is in further addition configured to output information to a driver of the vehicle 100, concerning the appropriate vehicle speed when said speed is within a predefined first thresh old from the calculated speed limitation. In some embodiments, the control arrangement 300 may be configured to determine speed of an ahead vehicle 350. Also, the control arrangement 300 may be configured to output information on the display 310 when the appropriate vehicle speed is within a predefined second threshold from the determined speed of the ahead vehicle 350.

The control arrangement 300 may also in some embodiments be configured to estimate the traffic situation ahead of the vehicle 100, between the position of the vehicle 100 and the traffic light 120. Also, the control arrangement 300 may be configured to refrain from output ting the information concerning the appropriate vehicle speed when the estimated traffic sit uation precludes arrival of the vehicle 100 to the traffic light 120 in a green period.

Further, in some embodiments, the control arrangement 300 may be configured to continu ously estimate the ahead traffic situation and recalculate the appropriate vehicle speed when a change in the traffic situation is detected.

The control arrangement 300 may in yet some embodiments also be configured for a cruise control functionality, and to adjust the cruise control of the vehicle 100 to the appropriate vehicle speed when said speed is within the predefined first threshold from the determined speed limitation, or when the appropriate vehicle speed is within the predefined second threshold from the determined speed of the ahead vehicle 350.

The system 600 also comprises a traffic light 120. Further, the system 600 comprises a transmitter 130, associated with the traffic light 120. Also, the system 600 comprises a re ceiver 140, configured to receive information from the transmitter 130. The receiver 140 may be comprised in the vehicle 100.

The control arrangement 300 may comprise a receiving circuit 610 configured for receiving a signal from the receiver 140 and / or the sensor 145.

The control arrangement 300 comprises a processing circuit 620 configured for performing at least some of the calculating and / or computing of the control arrangement 300. Thus, the processing circuitry 620 may be configured for calculating an appropriate vehicle speed of the vehicle 100.

Such processing circuit 620 may comprise one or more instances of a processing circuit, i.e. a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression“processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones enumerated above.

Furthermore, the control arrangement 300 may comprise a memory 625 in some embodi ments. The optional memory 625 may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory 625 may comprise integrated circuits comprising silicon- based transistors. The memory 625 may comprise e.g. a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embod iments.

Further, the control arrangement 300 may comprise a signal transmitter 630. The signal transmitter 630 may be configured for transmitting a control signal to be received by a display 310, or other output device for informing the driver, e.g. a loud speaker, a tactile device, a projector, etc.

The system 600 additionally may comprise a sensor 145, for estimating environmental traffic situation, in some embodiments.

However, in some alternative embodiments, the system 600 may comprise additional units for performing the method 500 according to at least some of the method steps 501 -509.

The previously described method steps 501 -509 to be performed in the system 600 may be implemented through the one or more processing circuits 620 within the control arrangement 300, together with computer program product for performing at least some of the functions of the steps 501 -509. Thus, a computer program product, comprising instructions for per forming the steps 501 -509 in the control arrangement 300 may perform the method 500 comprising at least some of the steps 501 -509 for calculating an appropriate vehicle speed of the vehicle 100.

The computer program product mentioned above may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the step 501 -509 according to some embodiments when being loaded into the one or more pro cessing circuits 620 of the control arrangement 300. The data carrier may be, e.g., a hard disk, a CD ROM disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer program product may furthermore be pro vided as computer program code on a server and downloaded to the control arrangement 300 remotely, e.g., over an Internet or an intranet connection.

The terminology used in the description of the embodiments as illustrated in the accompa nying drawings is not intended to be limiting of the described method 500; the control ar rangement 300; the computer program; the system 600 and / or the vehicle 100. Various changes, substitutions and / or alterations may be made, without departing from invention embodiments as defined by the appended claims.

As used herein, the term "and/ or" comprises any and all combinations of one or more of the associated listed items. The term“or” as used herein, is to be interpreted as a mathematical OR, i.e., as an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless ex pressly stated otherwise. In addition, the singular forms "a", "an" and "the" are to be inter preted as“at least one”, thus also possibly comprising a plurality of entities of the same kind, unless expressly stated otherwise. It will be further understood that the terms "includes", "comprises", "including" and / or "comprising", specifies the presence of stated features, ac- tions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, ele ments, components, and / or groups thereof. A single unit such as e.g. a processor may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/ distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms such as via Internet or other wired or wireless communication system.

Claims

PATENT CLAIMS

1. A method (500) of a control arrangement (300) in a vehicle (100), for calculating an appropriate vehicle speed of the vehicle (100), wherein the method (500) comprises the steps of:

detecting (501 ) a traffic light (120) ahead of the vehicle (100);

determining (502) a distance between the vehicle (100) and the detected (501 ) traf fic light (120);

acquiring (503) information concerning remaining time to next phase shift of the detected (501 ) traffic light (120);

determining (504) speed limitation on a road segment between the current vehicle position and the traffic light (120);

calculating (505) the appropriate vehicle speed in order to pass the traffic light (120) during a green period, without having to stop; and

outputting (508) information concerning the appropriate vehicle speed when said speed is within a predefined first threshold from the calculated (505) speed limitation.

2. The method (500) according to claim 1 , further comprising:

determining (506) speed of an ahead vehicle (350); and

wherein the information is outputted (508) when the appropriate vehicle speed is within a predefined second threshold from the determined (506) speed of the ahead vehicle (350).

3. The method (500) according to any one of claim 1 or claim 2, further comprising: estimating (507) the traffic situation ahead of the vehicle (100), between the position of the vehicle (100) and the traffic light (120); and

wherein the information concerning the appropriate vehicle speed is not outputted (507) when the estimated (507) traffic situation preclude arrival of the vehicle (100) to the traffic light (120) in a green period.

4. The method (500) according to claim 3, wherein the ahead traffic situation is con tinuously estimated (507) and the appropriate vehicle speed is recalculated when a change in the traffic situation is detected.

5. The method (500) according to any one of claims 1 -4, wherein the control arrange ment (300) is configured for a cruise control functionality, and wherein the method (500) further comprises: adjusting (509) the cruise control of the vehicle (100) to the appropriate vehicle speed when said speed is within the predefined first threshold from the determined (505) speed limitation, or when the appropriate vehicle speed is within the predefined second threshold from the determined (506) speed of the ahead vehicle (350).

6. A control arrangement (300) in a vehicle (100), for calculating an appropriate vehicle speed of the vehicle (100), wherein the control arrangement (300) is configured to:

detect a traffic light (120) ahead of the vehicle (100);

determine a distance between the vehicle (100) and the detected traffic light (120); acquire information concerning remaining time to next phase shift of the detected traffic light (120), via a communication device (140);

determine speed limitation on a road segment between the current vehicle position and the traffic light (120);

calculate the appropriate vehicle speed in order to pass the traffic light (120) during a green period, without having to stop; and

output information to a driver of the vehicle (100), concerning the appropriate vehi cle speed when said speed is within a predefined first threshold from the calculated speed limitation.

7. The control arrangement (300) according to claim 6, further configured to;

determine speed of an ahead vehicle (350); and

output information on the display (310) when the appropriate vehicle speed is within a predefined second threshold from the determined speed of the ahead vehicle (350).

8. The control arrangement (300) according to any one of claims 6-7, further config ured to:

estimate the traffic situation ahead of the vehicle (100), between the position of the vehicle (100) and the traffic light (120); and

refrain from outputting the information concerning the appropriate vehicle speed when the estimated traffic situation precludes arrival of the vehicle (100) to the traffic light (120) in a green period.

9. The control arrangement (300) according to any one of claims 6-8, further config ured to continuously estimate the ahead traffic situation and recalculate the appropriate ve hicle speed when a change in the traffic situation is detected.

10. The control arrangement (300) according to any one of claims 6-9, further config ured for a cruise control functionality, and to adjust the cruise control of the vehicle (100) to the appropriate vehicle speed when said speed is within the predefined first threshold from the determined speed limitation, or when the appropriate vehicle speed is within the prede- fined second threshold from the determined speed of the ahead vehicle (350).

1 1. A computer program comprising program code for performing a method (500) ac cording to any one of claims 1 -5 when the computer program is executed in a control ar rangement (300), according to any one of claims 6-10.

12. A system (600) for calculating an appropriate vehicle speed of the vehicle (100), which system (600) comprises:

a control arrangement (300) according to any one of claims 6-10;

a traffic light (120);

a transmitter (130), associated with the traffic light (120); and

a receiver (140), configured to receive information from the transmitter (130).

13. A vehicle (100) comprising a control arrangement (300) according to any one of claims 6-10.