Abstract:
The present system and method relates to light-display road signs, which inform about turns, dangers, road works, optimal speed to be driven etc. 
     A computer-implemented method for providing information at a road sign ( 110 ) comprising a display ( 110 ), the method being characterized in that it comprises the steps of: identifying the closest traffic light ( 130 ) ahead the road sign ( 100 ); retrieving operational information on the identified closest traffic light ( 130 ); processing the operational information to determine an optimal speed at which vehicles present in proximity to the location of the road sign ( 100 ) should move to arrive at the closest traffic light ( 130 ) when it is at green phase; and outputting the optimal speed via the display ( 110 ).

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    There is presented herein a system and a method for providing information at a road sign, in order to reduce traffic, optimize travel time and increase safety, especially within city limits. 
         [0003]    2. Description of the Related Art 
         [0004]    Traffic congestion is a well-known problem, especially in cities with a high number of crossroads. Traffic flow may be optimized by providing systems for management of traffic lights, but these systems have a reactive nature—they may adapt the traffic light to actual traffic conditions, but have limited capabilities of impacting individual vehicles to optimize their movement. 
         [0005]    Traffic management systems may be configured as a so-called ‘green wave’, where the main road has traffic lights configured such that a vehicle moving at a certain speed, for example 50 km/h, will reach the next traffic lights at a green light. The drawback of this system is that each driver shall maintain a particular optimal speed, for example 50 km/h, on the particular section of the road. However, in traffic conditions, a driver must adapt to other vehicles, which often means that it will not be possible to maintain the optimal speed in order to keep with the green wave. This especially happens when road sections between the traffic lights are long. 
         [0006]    A U.S. Pat. No. 5,519,390 discloses a traffic light timer, which provides a visible and accurate warning that a traffic light signal is about to change. The time remaining before the change is displayed in numeric form on a display and visibly counts down the seconds remaining. The display can be alphanumeric or graphical, allowing for the display of free form icons. Such timer may allow the driver to adapt the speed of travel to drive optimally, i.e. to slow down when the driver assumes that the light will soon change to red, or to speed up when the driver assumes that there is sufficient time to cross the road at green light. The drawback of the system is that it requires the driver to make own assessments and that it is effective only within the range of the eyesight of the driver. 
         [0007]    There are also known from prior art so called highway led displays, presenting real-time information to drivers. Such display is for example disclosed in a PCT application WO2011107380 that discloses a system and method for managing information display for vehicles on cross roads. The system includes at least one panel to display a traffic regulatory information and advertisements. 
         [0008]    Taking into account the aforementioned prior art publications, there exists a need to design a system and a method for providing information at a road sign, which will be useful for optimization of driving speed of individual vehicles and therefore may lead to reduction of overall traffic congestion. 
       SUMMARY 
       [0009]    There is presented a computer-implemented method for providing information at a road sign comprising a display, the method being characterized in that it comprises the steps of: identifying the closest traffic light ahead the road sign; retrieving operational information on the identified closest traffic light; processing the operational information to determine an optimal speed at which vehicles present in proximity to the location of the road sign should move to arrive at the closest traffic light when it is at green phase; and outputting the optimal speed via the display. 
         [0010]    Preferably, the operational information on the identified closest traffic light is retrieved from a remote traffic light server. 
         [0011]    Preferably, the optimal speed is determined by: determining the speed range necessary to arrive at the first green cycle of the closest traffic light; comparing the speed range with a speed limit; in case the speed range includes a range lower than the speed limit, determining the optimal speed as not greater than the speed limit; and otherwise, determining the speed range necessary to arrive at the next green cycle of the closest traffic light. 
         [0012]    Preferably, the optimal speed is further determined by: determining a second speed range necessary to arrive at the first green cycle of the next traffic light; comparing the second speed range with a speed limit; in case the second speed range includes a range lower than the speed limit, determining the second optimal speed as not greater than the speed limit and outputting an optimal speed which is in the range of intersection of the first speed range and the second speed range; and otherwise, determining the speed range necessary to arrive at the next green cycle of the closest traffic light. 
         [0013]    Preferably, the speed limit is selected depending on the type of the vehicle. 
         [0014]    Preferably, the speed limit is determined as the maximum allowed speed limit determined by a mapping system for the particular road region between the vehicle and the closest traffic light. 
         [0015]    Preferably, the speed limit is determined as an average speed stored in a history database for travel between the particular road region between the road sign and the traffic light. 
         [0016]    Preferably, the optimal speed is determined by determining the optimal speed as a speed within a range necessary to arrive at the green cycle of the closest traffic light and the next traffic light. 
         [0017]    Preferably, the method further comprises outputting via the display of the road sign, an indicator specifying whether the current speed of a vehicle approaching the road sign is within the calculated speed range, lower than the determined speed range or higher than the determined speed range. 
         [0018]    Preferably, the method further comprises obtaining geolocalization data of the road sign and identifying the closest traffic light ahead the road sign based on the geolocalization data. 
         [0019]    There is also presented a computer program comprising program code means for performing all the steps of the computer-implemented method as described above when said program is run on a computer, as well as a computer readable medium storing computer-executable instructions performing all the steps of the computer-implemented method as described above when executed on a computer. 
         [0020]    There is also presented a road sign, comprising a display for providing information for vehicles, the road sign being characterized in that it comprises: a data interface configured to retrieve operational information on the closest traffic light; a data processor configured to process the operational information to determine an optimal speed at which vehicles should move to arrive at the closest traffic light when it is at green phase; a user interface configured to output the optimal speed by means of the display. 
         [0021]    Preferably, the data interface is communicatively connected to a remote traffic light server. 
         [0022]    Preferably, the data interface is communicatively connected to the closest traffic light. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0023]    The system and method have been presented in an exemplary embodiment in a drawing, in which: 
           [0024]      FIG. 1  shows an exemplary traffic situation; 
           [0025]      FIG. 2  presents a block diagram of the components of the system; 
           [0026]      FIG. 3  presents example of the operational information on a traffic light; 
           [0027]      FIG. 4A  presents a general algorithm for calculating an optimal speed; and 
           [0028]      FIG. 4B  presents an algorithm for calculating an optimal speed for a plurality of traffic lights; and 
           [0029]      FIG. 5  presents an exemplary user interface of a road sign. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]      FIG. 1  shows an exemplary traffic situation, wherein a vehicle approaches a traffic light  130  and is currently at a distance D from that traffic light. 
         [0031]    According to the presented system and method, there are located, at different places (e.g. at a road side or above road, along the road or at a crossroad), road signs  100  comprising displays  110  (for example LED or LCD screens). Each road sign  100  is configured with its location data that may be stored in the road sign display or set at a traffic information server  120  with which the road signs may be communicatively coupled (unidirectionally or bidirectionally), wherein the server  120  also communicates with the traffic lights  130 . Alternatively, the road sign  100  may be equipped with a geolocalization module, such as GPS, in order to automatically determine and report its position. Alternatively a new control module may be communicatively coupled to existing road signs comprising display screens but lacking the speed recommendation function as described herein. 
         [0032]      FIG. 2  presents a diagram of the components of the system. 
         [0033]    The traffic information server  120  comprises a traffic lights database  121 , which stores, for each traffic light  130  handled by the system, information about light cycle. The content of the information about the light cycle may be dependent on the particular traffic lights management system used. For static systems, the information may include a list of light change times. For adaptive systems, the information may include only information about the next expected light change only, as the light may be operated adaptively to road conditions. 
         [0034]    The database  121  may also store other information, such as whether the given traffic light  130  is synchronized with the clock of the server  120 , information to which lane the traffic light applies, information on time at which the given traffic light is in an idle state (typically at night), information on speed limit in the vicinity of the traffic light. The server  120  is linked with the traffic lights  130  via a communication link  142 . 
         [0035]    The traffic information server  120  may further comprise a history database  122 , configured to store statistical historical data, such as typical travel times between two identified traffic lights, preferably taking into account the time of the day, type of the day (workday, weekend day, national holiday etc.). 
         [0036]    The history database  122  may be compiled based on traffic monitoring service. This data may be external of determined using different sensors and camera(s) present in the road sign  100 . 
         [0037]    Information from the traffic lights database  121  provides data describing current parameters of the environment, which are theoretical and may be not achievable in practice. For example, the speed limit allowable within the vicinity of the light may be in practice impossible to achieve in rush hours. The data from the traffic lights database  121  may be therefore corrected by data from historical database  122 , e.g. specifying that the average achievable maximum speed in a particular rush hour is e.g. 10 km/h lower than the actual speed limit. 
         [0038]    Data from the databases  121 ,  122  is processed by a data processor  123  and made accessible to users of the system by a data interface  124  as operational information on a particular traffic light  130 . 
         [0039]    Alternatively, the data interface  111  of the road sign can be communicatively connected (via a wired or wireless (e.g. GSM) interface) to the closest traffic light  130 . This allows to handle traffic lights which are not connected to a centralized traffic information server. 
         [0040]    An exemplary format of operational information on a traffic light is shown in  FIG. 3 . 
         [0041]    The system may be organized as a Service Oriented Architecture (SOA). The system may be implemented in Web Services technology, which is a distributed implementation software components provided by SOAP (Simple Object Access Protocol). Service Components of Web Services can be implemented using a variety of programming languages, hardware platforms and operating systems. In order to facilitate implementation of client applications, service components of Web Services are described in WSDL (Web Services Description Language), so that developers of client applications can use automatic generators of communication code. A further development of the solution is UDDI (Universal Description, Discovery and Integration) databases specification allowing to collect information on online Web services available. 
         [0042]    A road sign  100  comprises a data interface  111  for communicating with the data interface  124  of the server  120  via a communication link  141 . The communication  141  may be effected via a dedicated communication channel, or via standard communication channels, such as the Internet. 
         [0043]    The road sign  100  may optionally comprise a mapping system  114 , which can be a dedicated or third-party system configured to provide a map of the environment. The mapping system  114  may be embedded within the memory of the road sign  100  or can be accessible via Internet. The mapping system  114  is linked to an optional geolocalization module  115 , such as a Global Positioning System (GPS), that determines geographical coordinates of location of the road sign  110  (alternatively the geolocalization is hardcoded). The module may further comprise a database of traffic lights, defining the coordinates of the traffic lights  130  and their identifiers. Such mapping system can be used to automatically determine the closest traffic lights at which the road sign is installed. This is particularly useful when the road sign is a portable, non-stationary road sign, which can be installed at different places depending on needs to control the traffic within the city. Such road sign can automatically determine its position and orientation with respect to the closest traffic lights. 
         [0044]    A data processor  112  is configured to determine an optimal speed at which a vehicle, being at a location of a given road sign display  100 , should move in order to arrive at the closest traffic light  130  when it is at a green phase. A set of closest traffic lights in a given main direction may be considered in determining the optimal speed. 
         [0045]    The speed recommendation may be provided for all available lanes and may differ depending on the lane. For example a recommendation for the left lane may be 45 km/h, a recommendation for the middle lane may be 55 km/h while a recommendation for the right lane may be 30 km/h. This is useful when traffic lights have different cycles depending on respective lanes. 
         [0046]    The optimal speed can be calculated based on the general algorithm shown in  FIG. 4A . It starts in step  401  by determining the speed range at which the vehicle may reach the first green cycle of the traffic light (taking into account presence at the location of a given road sign  100 ), i.e. the current cycle if the traffic light is currently green or the next green cycle. Next, in step  402  the determined range is compared with a speed limit, which can be the lowest of
       the maximum allowed speed limit for the vehicle, e.g. 130 km/h for passenger cars, 90 km/h for trucks, 30 km/h for bicycles etc. (the road sign may comprise or be connected to appropriate vehicle type detector  140  to determine a type of the approaching vehicle—for example such sensor may be a camera provided with a suitable recognition mechanism that may be implemented as software and executed by the data processor  112 , alternatively a weight sensor or a coil sensor may be installed in the road surface at the vicinity of the road sign)   a default speed limit set by the system, e.g. 50 km/h;   the maximum allowed speed limit determined by the mapping system  114  for the particular road region between the road sign  100  and the closest traffic light  130 ;   the average speed determined by the history database  122  for travel between the particular road region between the road sign  100  and the traffic light  130  (which can be further dependent on the day of the week and time of day).       
 
         [0051]    In case the speed range includes a value lower than the speed limit, an optimal speed is selected and provided to the road sign  100  in step  403 . In case the whole speed range exceeds the speed limit, in step  404  the speed range to arrive at the next green cycle for the particular traffic light  130  is determined and the procedure returns to step  402 . 
         [0052]    The optimal speed in step  403  can be selected as one of:
       the average between the lowest value of the optimal speed range and the speed limit;   the speed limit decreased by a predetermined value, such as 5 km/h or 10%;   the speed limit.       
 
         [0056]    A skilled person will realize that the algorithm of  FIG. 4A  may be adapted by determining the optimal speed that will allow the vehicle to reach the green cycle at the closest traffic light and at the next traffic light. The next traffic light can be determined as the traffic light that is next in the direction of travel or a traffic light that is next on the route of travel planned in the mapping system  114 . 
         [0057]      FIG. 4B  presents an algorithm for calculating an optimal speed for a plurality of traffic lights. Steps  411 - 414  are equivalent to steps  401 - 404  of  FIG. 4A . Speed range 1 is the first speed range determined in step  411  that is between the minimum speed and the speed limit. Preferably, the highest speed of speed range 1 is output in step  413 . 
         [0058]    Next, in step  415  a second speed range is determined to arrive at the first green cycle at the next traffic light. In step  416  it is checked whether this speed range is within the speed limit and if not, the speed range is recalculated in step  418  for the following green cycle. If the speed range is within the speed limit, it is checked in step  419  whether the speed ranges calculated so far for all traffic lights have an intersection range. If there is an intersection range, in step  419  the optimal range is output and in step  420  a further speed range is calculated for a further traffic light. If the range is in case there is no intersection range, in step  421  the procedure determines speed range to arrive at the next green cycle at the next traffic light. 
         [0059]    The procedure continues until the most optimal speed is found for a determined plurality of traffic lights. 
         [0060]    The plurality of traffic lights may comprise traffic lights arranged consecutively along the main road at which the road sign is installed. 
         [0061]    The optimal speed is displayed via a user interface  113  of the display  110  of the road sign  100 , which may have a form as shown for example in  FIG. 5 . The user interface  501  may comprise a region speed information  503 , the speed information including information about the current speed  504  of the vehicle approaching the road sign (where the speed is measured by a speed radar  130  integrated with the road sign or connected to the road sign), the optimal speed  505  and the traffic light cycle information  506  about when the next green cycle will start or how long will the green cycle last. 
         [0062]    The current speed of a vehicle may be determined by means of a suitable sensor provided in the road sign ( 100 ). 
         [0063]    Additional visual feedback may be provided, e.g. by highlighting the background of the interface, for example:
       to green if the current speed is within the calculated speed range or optimal speed;   to red if the current speed is higher than the calculated speed range or optimal speed;   to blue if the current speed is lower than the calculated speed range or optimal speed.       
 
         [0067]    The additional feedback may also include comments such as “speed up” or “slow down”. 
         [0068]    In case the vehicle moves with a speed which is less than the calculated speed range or optimal speed for a relatively long period, it may suggest that the road is under heavy traffic conditions and it is not possible to achieve the expected optimal speed. In such a case the current speed may be used in step  402  as the speed limit to calculate the more optimal speed limit. 
         [0069]    The procedures of  FIG. 4A  or  4 B are preferably executed cyclically, e.g. every second, in order to provide to the user the most up-to-date information. The information may have to be updated due to the change of user&#39;s speed or a change of the traffic light cycle when adaptive traffic lights are used. 
         [0070]    A skilled person will realize that the algorithms of  FIGS. 4A and 4B  may be adapted to take into account the timing of yellow light, i.e. the periods between the green and red lights, without departing from the general inventive concept presented herein. 
         [0071]    In order to maintain reliable service, in case of a remote database  101 , a query result may also comprise a time stamp defining the time, at which it has been generated. The navigational module may then determine the time lag between the time at which the information about the light cycle was generated at the server  120  and at which is was actually processed by the data processor  112 . 
         [0072]    In case the traffic information server provides information that a particular traffic light is non-functioning, a special alert may be displayed to the user upon entering the area in the vicinity of that traffic light, so as to warn the user about possible dangerous road situations. 
         [0073]    It can be easily recognized, by one skilled in the art, that the aforementioned method for providing traffic information may be performed and/or controlled by one or more computer programs. Such computer programs can be executed by utilizing the computing resources of a processor installed in the road sign device. Applications are stored in non-volatile memory, for example a flash memory or volatile memory, for example RAM and are executed by a processor. These memories are exemplary recording media for storing computer programs comprising computer-executable instructions performing all the steps of the computer-implemented method according the technical concept presented herein. 
         [0074]    In another exemplary embodiment the aforementioned method for vehicle management in traffic conditions may be performed and/or controlled by one or more specialized hardware modules wherein the logic is embedded in programmable hardware circuits such as field-programmable gate array (FPGA). This would specially configure the device to execute functions presented in the foregoing specification. 
         [0075]    While the system and method presented herein have been depicted, described, and has been defined with reference to particular preferred embodiments, such references and examples of implementation in the foregoing specification do not imply any limitation on the concepts. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader scope of the technical concept. The presented preferred embodiments are exemplary only, and are not exhaustive of the scope of the technical concept presented herein. 
         [0076]    Accordingly, the scope of protection is not limited to the preferred embodiments described in the specification, but is only limited by the claims that follow. Any combination of the appended claims in envisaged in the present application.