Abstract:
An on-board vehicle warning system includes a location detecting section, a regulation retrieving section, an incoming message receiving section and a potential violation alerting section. The location detecting section detects respective geographic locations of a vehicle and a forthcoming intersection. The regulation retrieving section retrieves, based on the intersection location, a jurisdiction including local intersection regulation information pertaining to a vehicle position with respect to an intersection boundary at the time of a particular phase transition of a traffic light. The incoming message receiving section receives intersection status information of the intersection containing a geographic location of the boundary and phase information including a current phase and a time to the phase transition of a traffic light of the intersection. The potential violation alerting section estimates a future position of the vehicle with respect to the boundary at the occurrence of the phase transition to determine a potential violation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/045,274, filed on Mar. 10, 2008, the entire contents of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to an on-board vehicle warning system and a vehicle driver warning method. More specifically, the present invention relates to an on-board vehicle warning system and a vehicle driver warning method for producing a driver notification based on a determination of a potential traffic violation by a host vehicle. 
         [0004]    2. Background Information 
         [0005]    Recently, vehicles are being equipped with a variety of informational systems such as navigation systems, Sirius and XM satellite radio systems, two-way satellite services, built-in cell phones, DVD players and the like. These systems are sometimes interconnected for increased functionality. Various informational systems have been proposed that use wireless communications between vehicles and between infrastructures, such as roadside units. These wireless communications have a wide range of applications ranging from crash avoidance to entertainment systems. The type of wireless communications to be used depends on the particular application. Some examples of wireless technologies that are currently available include digital cellular systems, Bluetooth systems, wireless LAN systems and dedicated short range communications (DSRC) systems. 
         [0006]    Dedicated short range communications (DSRC) is an emerging technology that has been recently investigated for suitability in vehicles for a wide range of applications. DSRC technology will allow vehicles to communicate directly with other vehicles and with roadside units to exchange a wide range of information. In the United States, DSRC technology will use a high frequency radio transmission (5.9 GHz) that offers the potential to effectively support wireless data communications between vehicles, and between vehicles, roadside units and other infrastructure. The important feature of DSRC technology is that the latency time between communications is very low compared to most other technologies that are currently available. Another important feature of DSRC technology is the capability of conducting both point-to-point wireless communications and broadcast wireless messages in a limited broadcast area. 
         [0007]    Accordingly, wireless technology can be used to provide various information from vehicle-to/from-infrastructure, and from vehicle-to-vehicle, such as providing GPS location, vehicle speed and other vehicle Parameter Identifiers (PIDs) including engine speed, engine run time, engine coolant temperature, barometric pressure, etc. The standard message set to be passed between vehicles, and between vehicles and the infrastructure using DSRC is covered by Society of Automotive Engineers (SAE) J2735-DSRC Message Set Dictionary. When communications are established between vehicles and/or roadside units in close proximity, this information would be communicated to provide a complete understanding of the vehicles in the broadcast area. This information then can be used by the vehicles for both vehicle safety applications and non-safety applications. 
         [0008]    Recently, the Cooperative Intersection Collision Avoidance Systems (CICAS) initiative was launched to develop vehicle-infrastructure cooperative systems that address intersection crash problems related to stop sign violations, traffic signal violations, etc. One of the programs included in the CICAS initiative is the violation warning system (CICAS-Violation) that warns the driver via an in-vehicle device when it appears likely that the driver will violate a traffic signal or stop sign. More specifically, with the violation warning system, the roadside unit coupled to the traffic light device at the intersection sends intersection information including, signal presence, signal state (phase), and intersection map, etc. to the on-board equipment mounted on the vehicle. Then, the on-board equipment uses the intersection information and vehicle information to provide the driver of the vehicle with a timely warning of a potential traffic control violation (e.g., running a red light). 
         [0009]    In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved on-board vehicle warning system and vehicle driver warning method. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure. 
       SUMMARY OF THE INVENTION 
       [0010]    The traffic laws and regulations vary from jurisdiction to jurisdiction. For example, although failing to stop for a red light is usually a legal offence in most jurisdictions, the definition of what constitutes the red-light running violation may be different from jurisdiction to jurisdiction. Under the traffic regulations of some jurisdiction, no offence has been committed as long as the light is yellow when the vehicle enters the intersection, while, under the traffic regulations of other jurisdictions, an offence occurs if the light turns red at any time before the vehicle clears the intersection. Also, some jurisdictions may have a stricter standard in which running a yellow light is an offence unless the vehicle is unable to stop safely. Thus, generally speaking, there are two approaches to traffic regulations pertaining traffic signals. Some jurisdictions allow vehicles to enter intersections on a yellow light while other jurisdictions permit vehicles to enter intersections only on a green light. In the latter case, warnings and advisories would need to be issued earlier as compared to the former case. However, the conventional traffic signal violation warning systems do not take into account those differences in the traffic regulations among different jurisdictions. Thus, with a single set of parameters tuned to the case where vehicles are only permitted in the intersection on a green light, warnings and advisories may be issued prematurely in jurisdictions where vehicles are allowed in the intersection on a yellow light. In these cases, the warning and advisories could be considered a nuisance to the driver. 
         [0011]    Therefore, one object of the present invention is to provide an on-board vehicle warning system and a vehicle driver warning method that can properly warn the driver of the potential traffic light violation according to the local traffic regulation corresponding to the current location of the vehicle. 
         [0012]    In order to achieve the above identified object, an on-board vehicle warning system includes a location detecting section, a regulation retrieving section, an incoming message receiving section and a potential violation alerting section. The location detecting section is configured to detect a geographic location of a host vehicle equipped with the on-board vehicle warning system, and a geographic location of a forthcoming intersection. The regulation retrieving section is configured to retrieve a jurisdiction based on the geographic location of the forthcoming intersection. The jurisdiction includes local intersection regulation information containing information pertaining to a vehicle position with respect to an intersection boundary at the time of a particular phase transition of a traffic light device. The incoming message receiving section is configured to receive intersection status information of the forthcoming intersection containing a geographic location of a boundary of the forthcoming intersection and phase information including a current phase and a time to the particular phase transition of a traffic light device of the forthcoming intersection. The potential violation alerting section is configured to estimate a future position at which the host vehicle will be with respect to the boundary of the forthcoming intersection at the time that the particular phase transition is going to occur to determine a potential violation. 
         [0013]    These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Referring now to the attached drawings which form a part of this original disclosure: 
           [0015]      FIG. 1  is a pictorial representation of a wireless communications network showing several vehicles equipped with an on-board unit capable of conducting wireless communications with each other and as well as an external server via a plurality of roadside units in a vehicle infrastructure system in accordance with one embodiment of the present invention; 
           [0016]      FIG. 2  is a schematic representation of a vehicle that is equipped with the on-board vehicle warning system in accordance with the illustrated embodiment of the present invention; 
           [0017]      FIG. 3  is a pictorial representation of the wireless communications network showing the communications between an intersection unit and the on-board vehicle warning system via the roadside unit in the vehicle infrastructure system in accordance with the illustrated embodiment of the present invention; 
           [0018]      FIG. 4  is an inside elevational view of a portion of the vehicle&#39;s interior that is equipped with the on-board vehicle warning system in accordance with the illustrated embodiment of the present invention; 
           [0019]      FIG. 5  is a pictorial representation for explaining timings for issuing an advisory and a warning in the on-board vehicle warning system in accordance with the illustrated embodiment of the present invention; 
           [0020]      FIG. 6  is a schematic representation showing various reference points in the intersection that are contained in the geometric intersection description (GID) information received by the on-board vehicle warning system in accordance with the illustrated embodiment of the present invention; 
           [0021]      FIG. 7  is a table showing an example for storing various advisory/warning parameters according to various traffic regulations in accordance with the illustrated embodiment of the present invention; 
           [0022]      FIG. 8  is a flowchart showing a main control flow executed by the on-board vehicle warning system in accordance with the illustrated embodiment of the present invention; and 
           [0023]      FIG. 9  is a flowchart showing a control flow executed by the on-board vehicle warning system for issuing the advisory and/or the warning in accordance with the illustrated embodiment of the present invention when the vehicle is located in the jurisdiction in which an offence occurs if the light turns red at any time before the vehicle clears the intersection. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Selected embodiment of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following description of the embodiment of the present invention is provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
         [0025]    Referring initially to  FIG. 1 , a wireless communications network is illustrated that forms a part of a vehicle infrastructure system in accordance with one embodiment of the present invention. In this vehicle infrastructure system, at least one of a plurality of vehicles  10  is equipped with an on-board vehicle warning system  12  in accordance with one embodiment of the present invention. The wireless communications network also preferably includes one or more global positioning satellites  14  (only one shown), and one or more roadside units  16  and a base station or external server  18 . The roadside units  16  are configured to relay signals between the on-board vehicle warning system  12  of the host vehicle  10  and the external server  18 . Thus, the roadside units  16  are configured to send signals to the external server  18  and the on-board vehicle warning system  12  of the host vehicle  10 , and receive signals from the on-board vehicle warning system  12  of the host vehicle  10  and the external server  18 . Moreover, as shown in  FIG. 1 , an intersection unit  17  is provided in each of the traffic intersections for producing intersection information relating to the corresponding intersection. The intersection unit  17  is operatively coupled to the roadside unit  16  so that the traffic intersection information is communicated between the intersection unit  17  and the on-board vehicle warning system  12  of the host vehicle  10  via the roadside unit  16  when the host vehicle  10  enters within the broadcast range of the roadside unit  16 . As explained in more detail below, the on-board vehicle warning system  12  is configured and arranged to determine a potential traffic violation by the host vehicle  10  with respect to a traffic control device (e.g., a traffic light device) in front of the host vehicle  10  according to the local traffic regulation corresponding to the current location of the host vehicle  10 . Then, the on-board vehicle warning system  12  is configured to produce a driver notification to a driver of the host vehicle  10  based upon a determination of the potential traffic violation. In this system, the term “host vehicle” refers to a vehicle equipped with the wireless communications system with which the traffic intersection information is received from the intersection unit  17  via the roadside unit  16  in accordance with the illustrated embodiment. 
         [0026]    Referring now to  FIG. 2 , the on-board vehicle warning system  12  basically includes a controller or control unit  20 , a wireless communication system  21  and a human-machine interface section  22 . The control unit  20  and the human-machine interface section  22  cooperate together to constitute a driver alerting component that is configured to issue a driver notification (e.g., an advisory and/or a warning) regarding the potential traffic violation by the host vehicle  10 . Also, the control unit  20  and the wireless communication system  21  cooperate together to constitute an incoming message receiving component that is configured to receive the intersection information from the intersection unit  17  via the roadside unit  16 . 
         [0027]    The wireless communication system  21  is configured and arranged such that the control unit  20  receives and/or sends various signals to other DSRC equipped component and systems in the communication (broadcasting/receiving) area that surrounds the host vehicle  10 . The human-machine interface section  22  includes a screen display  22 A (see  FIG. 4 ), an audio speaker  22 B and a plurality of manual input controls  22 C (see  FIG. 4 ) that are operatively coupled to the control unit  20 . The control unit  20  is also preferably coupled to a global positioning system  23  having a GPS unit  23 A and a GPS antenna  23 B. The control unit  20  and the global positioning system  23  cooperate together to constitute a vehicle location detecting component that is configured to detect a current location of the host vehicle  10 . A map database and storage section  25  (an on-board storage device) is also preferably provided that contains various data used by the control unit  20  to carry out the navigation controls as well as implementation of various safety measures including the potential traffic violation determination process. More specifically, in the illustrated embodiment, the map database and storage section  25  preferably stores traffic regulation data including information indicative of different traffic regulations relating to a plurality of jurisdictions (e.g., the traffic regulations of all States in the United States). The map database and storage section  25  can be manually updated through removable media (CD-ROM or DVD) or automatically updated via periodic communications with the external server  18 . The control unit  20 , the human-machine interface section  22 , the global positioning system  23  and the map database and storage section  25  are operatively connected together to perform the various navigation functions, and thus, preferably constitute an on-board navigation unit. The navigation functions controlled by the control unit  20  are conventional, and thus, the navigation functions of the control unit  20  will not be discussed herein. Alternatively, the external server  18  can be used to communicate with the on-board vehicle warning system  12  to provide the off-board navigation service (dynamic navigation system) through wireless communications via the roadside units  16  within the wireless communications network, if need and/or desired. 
         [0028]    Moreover, the control unit  20  of the on-board vehicle warning system  12  is configured to receive detection signals via the vehicle CAN bus from various in-vehicle sensors including, but not limited to, an ignition switch sensor, an accessory switch sensor, a vehicle speed sensor, an acceleration sensor, a throttle position sensor, a brake switch sensor, etc. 
         [0029]    Still referring to  FIG. 2 , the vehicle  10  is basically a conventional vehicle which has been modified to incorporate the on-board vehicle warning system  12 . Thus, the conventional parts of the vehicle  10  will not be discussed and/or illustrated herein. Rather, only those parts that interact with and/or related to the on-board vehicle warning system  12  will be discussed and/or illustrated herein as needed to understand the illustrated embodiment. The vehicle  10  is provided with a steering structure  26 , a steering vibrating device  28 , and a visual warning indicator  30  as well as other parts not shown. The steering vibrating device  28  is operatively controlled by the control unit  20  to vibrate the steering wheel of the steering structure  26  when the control unit  20  determines that it is desirable to warn the driver of a safety concern such as a potential traffic light violation. The visual warning indicator  30  is operatively controlled by the control unit  20  to provide a visual warning to the driver when a signal is received indicating a safety concern such as the potential traffic light violation. 
         [0030]    The control unit  20  is operatively connected to the wireless communication system  21 , the human-machine interface section  22 , the global positioning system  23 , the map database and storage section  25 , the steering vibrating device  28 , and the visual warning indicator  30 . The control programs of the control unit  20  is programmed to include functions that can be generally divided into a vehicle location detecting section, a traffic regulation retrieving section, a incoming message receiving section, a vehicle information detecting section, and a potential violation alerting section. 
         [0031]    The vehicle location detecting section of the control unit  20  is configured to detect a current location of the host vehicle  10  based on the information received from the global positioning system  23 . 
         [0032]    The traffic regulation retrieving section of the control unit  20  is configured to retrieve information relating to a local traffic regulation that is in effect in the current location of the host vehicle  10  detected by the vehicle location detecting section. More specifically, the traffic regulation retrieving section is preferably configured to read the information relating to the local traffic regulation from the map database and storage section  25 . As mentioned above, the map database and storage section  25  stores the traffic regulation data including the traffic regulations relating to different jurisdictions. Alternatively, the traffic regulation retrieving section of the control unit  20  can be configured to wirelessly download the information relating to the local traffic regulation corresponding to the current location of the host vehicle  10  from an external server (e.g., the external server  18 ) that stores the traffic regulation data of different jurisdictions via the Internet link or the like. 
         [0033]    The incoming message receiving section of the control unit  20  is configured to receive the intersection information of the upcoming traffic intersection from the intersection unit  17  via the roadside unit  16  when the host vehicle  10  enters within the broadcast range of the roadside unit  16 . 
         [0034]    The vehicle information detecting section of the control unit  20  is configured to detect vehicle travel information of the host vehicle  10 . More specifically, the vehicle information detecting section is configured to process the various signals relating to the current traveling condition of the host vehicle  10  received from the in-vehicle sensors and other components (e.g., the global positioning system  23 ) operatively connected to the control unit  20 . For example, the vehicle information detected by the vehicle information detecting section includes the vehicle acceleration/deceleration, the current speed, the position of the host vehicle  10  with respect to the upcoming intersection, and the like. 
         [0035]    The potential violation alerting section of the control unit  20  is configured to determine whether the host vehicle  10  is likely to commit a traffic violation with respect to the upcoming intersection based on the intersection information received by the incoming message receiving section and the vehicle travel information detected by the vehicle travel information detecting section. Moreover, the potential violation alerting section is further configured to produce a driver notification (the advisory and/or the warning) to the driver of the host vehicle  10  based upon a determination of the potential traffic violation according to the local traffic regulation corresponding to the location of the host vehicle. More specifically, the potential violation alerting section is configured to adjust a parameter indicative of a distance between the traffic intersection and the position of the host vehicle at which the driver notification is produced according to the local traffic regulation corresponding to the location of the host vehicle. 
         [0036]    The potential violation alerting section is further configured to produce the driver notification by using the human-machine interface section  22 , the steering structure  26  and/or the visual warning indicator  30 . For example, in the illustrated embodiment, the potential violation alerting section of the control unit  20  is preferably configured to produce the driver notification using the visual warning indicator  30  to project a visual advisory signal or a visual warning signal on the windshield (see  FIG. 4 ) of the host vehicle  10  as part of the driver notification. Also, in the illustrated embodiment, the potential violation alerting section of the control unit  20  is preferably further configured to produce an audible signal using the audio speaker  22 B as part of the driver notification in addition to the visual signal produced by the visual warning indicator  30 . Alternatively, a haptic warning signal can be used in addition to or instead of the visual signal and the audible signal to alert the driver of the potential traffic violation. For example, the steering vibrating device  28  can vibrate the steering wheel of the steering structure  26  when the control unit  20  determines that it is desirable to warn the driver of the potential traffic violation as part of the driver notification. In other words, any combination of visual signals, auditory signals and haptic signals can be used to produce the driver notification to alert the driver of the potential traffic violation. 
         [0037]    The control unit  20  preferably includes a microcomputer with a potential traffic violation determining program and a driver warning program. The control unit  20  also preferably includes other conventional sections such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. The memory circuit stores processing results and control programs such as ones for operation of the wireless communication system  21 , the human-machine interface section  22 , the global positioning system  23 , the map database and storage section  25 , the steering vibrating device  28  and the visual warning indicator  30 . The control unit  20  is capable of selectively controlling other DSRC sections of the host vehicle  10  such as other safety systems as needed and/or desired. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the control unit  20  can be any combination of hardware and software that will carry out the functions of the present invention. 
         [0038]    The wireless communication system  21  preferably includes communication interface circuitry that connects and exchanges information with the roadside units  16  through a wireless network within the broadcast range of the host vehicle  10 . The wireless communication system  21  is preferably configured and arranged to conduct direct two-way communications between the host vehicle  10  and the roadside units  16  (roadside-to-vehicle communications). Moreover, the wireless communication system  21  can also be configured and arranged to conduct direct two-way communications with other vehicles that are similarly equipped with the wireless communication system  21  (vehicle-to-vehicle communications). 
         [0039]    More specifically, as seen in  FIG. 2 , the wireless communication system  21  is an on-board unit that includes a two-way communication device  21 A and one or more antennas  21 B. The wireless communication system  21  can be any suitable wireless system, e.g., DSRC cellular, Wimax, Wifi, etc. In other words, while the wireless communications network is illustrated as a dedicated short range communications (DSRC) network in this embodiment, it will be apparent to those skilled in the art from this disclosure that other types of wireless communications networks such as cellular, Wimax, Wifi, etc can be used as a wireless communications network to carry out the present invention. The two-way communication device  21 A is configured to at least conduct direct short range communications in a host vehicle broadcast area surrounding the host vehicle  10  via the antennas  21 B. Preferably, the antennas  21 B include both an omni-directional antenna and a multi-directional antenna. In one preferred embodiment, the wireless communication system  21  is a dedicated short range communication (DSRC) system, since the latency time between communications is very low compared to most other technologies that are currently available. However, other wireless communication systems can be used if they are capable of conducting both point-to-point wireless communications and broadcast wireless messages in a limited broadcast area so long as the latency time between communications is short enough to carry out the present invention. When the wireless communication system  21  is a DSRC system, the wireless communication system  21  will transmit at a 75 Mhz spectrum in a 5.9 GHz band with a data rate of 1 to 27 Mbps, and a maximum range of about 1,000 meters. The wireless communication system  21  will be assigned a Medium Access Control (MAC) address and/or an IP address so that each vehicle in the network can be individually identified. 
         [0040]    The global positioning system  23  is a conventional global positioning system (GPS) that is configured and arranged to receive global positioning information of the host vehicle  10  in a conventional manner. Basically, the GPS unit  23 A is a receiver for receiving a signal from the global positioning satellite  14  ( FIG. 1 ) via the GPS antenna  23 B. The signal transmitted from the global positioning satellite  14  is received at regular intervals (e.g. one second) to detect the present position of the host vehicle  10 . The GPS unit  23 A preferably has an accuracy of indicting the actual vehicle position within a few meters or less. This data (present position of the host vehicle) is fed to the control unit  20  for processing. Moreover, the GPS data is also transmitted to the roadside units  16  through wireless communications for the off-board (dynamic) navigation processing. 
         [0041]    The roadside units  16  are configured to obtain positions of the host vehicles  10  that are traveling along various routes. The wireless communication system  21  of the host vehicle  10  communicates with the roadside units  16  along the travel route. The roadside units  16  are positioned at various distances along different routes. Since roadside units are known in the art, the structures of the roadside units  16  will not be discussed or illustrated in detail herein. Rather, it will be apparent to those skilled in the art from this disclosure that the roadside unit can be any type of structure that can be used to carry out the present invention. 
         [0042]    As seen in  FIG. 3 , the wireless communications are conducted between the vehicles  10  and the roadside unit  16  that is disposed in the vicinity of the upcoming intersection. The intersection unit  17  is operatively coupled to the roadside unit  16  so that the traffic intersection information can be communicated from the intersection unit  17  to the on-board vehicle warning system  12  of the host vehicle  10  via the roadside unit  16 . Moreover, the intersection unit  17  is preferably configured to periodically broadcast a signal indicative of the traffic intersection information and the basic Safety (heartbeat) message in the broadcast area via the roadside unit  16 . The signal can be broadcasted in three different way, i.e., (1) event based broadcasting, (2) periodic broadcasting (e.g., every 100 msec) and (3) hybrid (event based/periodic) broadcasting. Preferably, periodic broadcasting or hybrid (event based/periodic) broadcasting is used to carry out the illustrated embodiment. 
         [0043]    The traffic intersection information sent from the intersection unit  17  to the host vehicle  10  includes, for example, the geometric intersection description (GID) information, the signal phase and timing (SPAT) information, the GPS correction information, the road condition information, etc. The GID information is a small map that describes the intersection geometry, including intersection reference points (see  FIG. 6 ), intersection orientation, stop bar locations for all lanes in the intersection, number of lanes per approach, lane geometry, starting point for new lanes, lane number, etc. The SPAT information contains the current signal phase and the time to phase change in the traffic light device for each lane. 
         [0044]    As shown in  FIG. 5 , when the host vehicle  10  approaches the upcoming intersection, the on-board vehicle warning system  12  receives the intersection information from the intersection unit  17  via the roadside unit  16 . Then the control unit  20  is configured to calculate various parameters such as an advisory distance (d_advisory) (i.e., the distance to the stop bar at which the advisory is issued), a warning distance (d_warning) (i.e., the distance to the stop bar at which the warning is issued), a distance from the current position of the host vehicle  10  to the stop bar (d(t)), a width of the intersection (w_intersection), a clearance distance (d_clear) (i.e., the distance from the stop bar at which the host vehicle  10  exits from the intersection). 
         [0045]    Calculation of Advisory Distance (d_advisory) 
         [0046]    The advisory distance (d_advisory) is a distance to the stop bar at which the advisory is issued. The advisory is intended to give the driver of the host vehicle  10  preview information about an impending phase change. In other words, the advisory indicates that if the host vehicle  10  continues to travel at the current vehicle speed (v 0 ), the signal will be in such a phase that the host vehicle  10  will commit a signal violation before the host vehicle  10  clears the intersection. Thus, the control unit  20  is configured to issue an advisory upon the host vehicle  10  reaching the advisory distance (d_advisory) with respect to the traffic intersection (the stop bar) which requires the host vehicle  10  to decelerate at a prescribed rate in order to stop before it reaches the traffic intersection. The advisory distance (d_advisory) is calculated according to the equation (1) below. 
         [0000]        d _advisory= d _react+ d _decel+ d _margin+ d _hys+ d _mingap  (1)
 
         [0047]    In the equation (1), the value “d_react” represents a reaction distance, the value “d_decel” represents a deceleration distance, the value “d_mingap” represents a minimum distance to the stop bar, the value “d_margin” represents a margin from the stop bar, the value “d_hys” represents the hysteresis. The minimum distance “d_mingap”, the margin “d_margin”, and the hysteresis “d_hys” are preferably set in advance to appropriate values. 
         [0048]    The reaction distance “d_react” is a distance traveled while traveling at the current speed until the braking is first applied. The reaction distance “d_react” is calculated according to the equation (2) below. 
         [0000]        d _react= v   0   ·t _react  (2)
 
         [0049]    In the equation (2) above, the value “v 0 ” represents the current vehicle speed (m/s) and the value “t_react” represents a reaction time. The reaction time “t_react” is preferably set in advance to an appropriate value. 
         [0050]    The deceleration distance “d_decel” in the equation (1) is a distance traveled from the time the braking is first applied until the vehicle stops. The deceleration distance “d_decel” is calculated according to the equation (3) below. 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         d_decel 
                         = 
                           
                          
                         
                           
                             
                               
                                 ( 
                                 
                                   v_rel 
                                   + 
                                   
                                     ( 
                                     
                                       
                                         a_est 
                                         2 
                                       
                                       
                                         2 
                                          
                                         
                                             
                                         
                                          
                                         J_est 
                                       
                                     
                                     ) 
                                   
                                 
                                 ) 
                               
                               2 
                             
                             
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                           - 
                           
                             
                               a_est 
                               3 
                             
                             
                               6 
                                
                               
                                   
                               
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                                 J_est 
                                 2 
                               
                             
                           
                         
                       
                     
                   
                   
                     
                       
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                               v 
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                               2 
                             
                             
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                                 J_est 
                               
                             
                              
                             
                               v 
                               0 
                             
                           
                           - 
                           
                             
                               a_est 
                               3 
                             
                             
                               24 
                                
                               
                                   
                               
                                
                               
                                 J_est 
                                 2 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
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         [0051]    In the equation (3), the value “v 0 ” represents the current vehicle speed (m/s), the value “a_est” represents an estimated deceleration, and the value “J_est” represents an estimated jerk. The estimated deceleration “a_est” and the estimated jerk “J_est” are preferably set in advance to appropriate values. 
         [0052]    Calculation of Warning Distance (d_warning) 
         [0053]    The warning distance (d_warning) is a distance to the stop bar at which the warning is issued. The warning is intended to keep the host vehicle  10  from committing the signal violation. Thus, the warning indicates that an action must be taken immediately to stop the host vehicle  10  in order to avoid the traffic signal violation. The control unit  20  is configured to issue a warning upon the host vehicle  10  reaching the warning distance (d_warning) with respect to the traffic intersection (the stop bar) which requires the host vehicle  10  to decelerate at a prescribed rate in order to stop before it reaches the traffic intersection. The warning distance (d_warning) is calculated according to the equation (4) below. 
         [0000]        d _warning= d _react+ d _decel+ d _margin+ d _hys  (4)
 
         [0054]    In the equation (4), the value “d_react” represents the reaction distance, the value “d_decel” represents the deceleration distance, the value “d_margin” represents the margin from the stop bar, and the value “d_hys” represents the hysteresis. The margin “d_margin”, and the hysteresis “d_hys” are preferably set in advance to appropriate values. The reaction distance “d_react” is calculated according to the equation (2) as explained above. The deceleration distance “d_decel” is calculated according to the equation (3) as explained above. 
         [0055]    Calculation of Width of Intersection (w_intersection) 
         [0056]    The calculation of the width of the intersection (w_intersection) will be explained with reference to  FIG. 6 . The width of the intersection (w_intersection) as illustrated in  FIG. 6  can be calculated based on the geometric intersection description (GID) information received from the intersection unit  17  via the roadside unit  16 . More specifically, the GID information includes the information of various reference points for the intersection as shown in  FIG. 6 . Based on the information of the references points, the width of the intersection (w_intersection) can be calculated according to the equation (5) below. 
         [0000]        w _intersection=( y _offset01+ y _offset11)cos ω  (5)
 
         [0057]    In the equation (5), the value “ω” represents the vehicle heading. 
         [0058]    Calculation of Distance to Stop Bar (d(t)) 
         [0059]    The distance to the stop bar (d(t)) is initially calculated as an initial distance to the stop bar (d 0 ) according to the equation (6) below. 
         [0000]    
       
         
           
             
               
                 
                   
                     d 
                     0 
                   
                   = 
                   
                     
                       ( 
                       
                         1 
                         - 
                         f 
                       
                       ) 
                     
                      
                     
                       r 
                       e 
                     
                      
                     
                       
                         
                           
                             
                               
                                 ( 
                                 
                                   
                                     θ 
                                     
                                       vp 
                                        
                                       
                                           
                                       
                                        
                                       0 
                                     
                                   
                                   - 
                                   
                                     θ 
                                      
                                     
                                         
                                     
                                      
                                     sb 
                                   
                                 
                                 ) 
                               
                               2 
                             
                              
                             
                               cos 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                           + 
                           
                             
                               ( 
                               
                                 
                                   ϕ 
                                   
                                     vp 
                                      
                                     
                                         
                                     
                                      
                                     0 
                                   
                                 
                                 - 
                                 
                                   ϕ 
                                   sb 
                                 
                               
                               ) 
                             
                             2 
                           
                         
                         
                           
                             
                               sin 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                           + 
                           
                             
                               
                                 ( 
                                 
                                   1 
                                   - 
                                   f 
                                 
                                 ) 
                               
                               2 
                             
                              
                             
                               cos 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
         [0060]    In the equation (6), the value “r e ” is the primary parameter in the World Geodetic System—1984 (WGS84) coordination system defining the semimajor axis, which is set to 6,378,137 m. The value “f” is the primary parameter in the WGS84 coordination system defining the flattening, which is set to 1/298.257223563. The value “θ vp0 ” represents the initial vehicle longitude, the value “φ vp0 ” represents the initial vehicle latitude, the value “θ sb ” represents the stop bar longitude and the value “φ sb ” represents the stop bar latitude. The vehicle longitude “θ vp0 ” and the vehicle latitude “φ vp0 ” are preferably determined based on the information received in the global positioning system  23 . 
         [0061]    For the subsequent calculation, the distance to the stop bar (d(t)) is calculated by updating the initial vehicle longitude “θ vp0 ” and the initial vehicle latitude “φ vp0 ” in the equation (6) above to the current vehicle longitude “θ vs(t) ” and the current vehicle latitude “φ vp(t) ” as the equation (6)′ below. 
         [0000]    
       
         
           
             
               
                 
                   
                     d 
                      
                     
                       ( 
                       t 
                       ) 
                     
                   
                   = 
                   
                     
                       ( 
                       
                         1 
                         - 
                         f 
                       
                       ) 
                     
                      
                     
                       r 
                       e 
                     
                      
                     
                       
                         
                           
                             
                               
                                 ( 
                                 
                                   
                                     θ 
                                     
                                       vp 
                                        
                                       
                                           
                                       
                                        
                                       
                                         ( 
                                         i 
                                         ) 
                                       
                                     
                                   
                                   - 
                                   
                                     θ 
                                      
                                     
                                         
                                     
                                      
                                     sb 
                                   
                                 
                                 ) 
                               
                               2 
                             
                              
                             
                               cos 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                           + 
                           
                             
                               ( 
                               
                                 
                                   ϕ 
                                   
                                     vp 
                                      
                                     
                                         
                                     
                                      
                                     
                                       ( 
                                       i 
                                       ) 
                                     
                                   
                                 
                                 - 
                                 
                                   ϕ 
                                   sb 
                                 
                               
                               ) 
                             
                             2 
                           
                         
                         
                           
                             
                               sin 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                           + 
                           
                             
                               
                                 ( 
                                 
                                   1 
                                   - 
                                   f 
                                 
                                 ) 
                               
                               2 
                             
                              
                             
                               cos 
                               2 
                             
                              
                             
                               ϕ 
                               sb 
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   
                     ( 
                     6 
                     ) 
                   
                   ′ 
                 
               
             
           
         
       
     
         [0062]    Alternatively, the updated distance to the stop bar (d(t)) can be calculated using the equation (7) below. 
         [0000]        d ( t )= d ( t− 1)+ v   0   ·t   (7)
 
         [0063]    Calculation of Clearance Distance (d_clear) 
         [0064]    The clearance distance (d_clear) is a distance from the stop bar at which the host vehicle  10  completely exits from the intersection. The clearance distance (d_clear) is calculated according to the equation (8) below. 
         [0000]        d _clear=−( w _intersection+ l _vehicle)  (8)
 
         [0065]    In the equation (8) above, the value “l_vehicle” represents a longitudinal length of the vehicle body of the host vehicle  10 . The longitudinal length “l_vehicle” is preferably measured and stored in the map database and storage section  25  in advance. Thus, the control unit  20  is configured to determine the potential traffic violation by taking into account the longitudinal length “l_vehicle” of the vehicle body of the host vehicle  10  to calculate timings at which the host vehicle  10  enters the traffic intersection and exits the traffic intersection. 
         [0066]    In the illustrated embodiment, the control unit  20  is preferably configured to adjust the advisory/warning parameters (e.g., the minimum gap “d_mingap”, the margin “d_margin” and the hysteresis “d_hys”) used in the equations (1) and (4) above for determining the advisory distance (d_advisory) and the warning distance (d_warning), respectively, corresponding to the local traffic regulation that is in effect in the current location of the host vehicle  10 . As mentioned above, there are two general approaches to traffic regulations pertaining to traffic signals. Some jurisdictions allow vehicles to enter intersections on a yellow light while other jurisdictions permit vehicles to enter intersections only on a green light. In the latter case, warnings and advisories are preferably issued earlier as compared to the former case. Thus, the control unit  20  is configured to adjust the advisory/warning parameters for determining the timings at which the advisory and the warning are issued (i.e., the advisory distance (d_advisory) and the warning distance (d_warning)) according to the local traffic regulation corresponding to the current location of the host vehicle  10 . 
         [0067]    For example, if the traffic regulation in effect in the current location of the host vehicle  10  permits vehicles to enter intersections only on a green light, then the control unit  20  is configured to load the advisory/warning parameters corresponding to such traffic regulation so that the advisory and/or warning is issued at relatively early timing. On the other hand, if the traffic regulation in effect in the current location of the host vehicle  10  allows vehicles to enter intersections on a yellow light, then the control unit  20  is configured to load the advisory/warning parameters corresponding to such traffic regulation so that the advisory and/or warning is issued at appropriate timing. 
         [0068]      FIG. 7  shows a table that is used in one example for determining the advisory/warning parameters (e.g., the minimum gap “d_mingap”, the margin “d_margin” and the hysteresis “d_hys”) corresponding to the local traffic regulation for calculating the advisory distance (d_advisory) and the warning distance (d_warning), respectively, according to the equations (1) and (4) above. Based on the current location of the host vehicle  10 , the control unit  20  is preferably configured to refer to a database stored in the map database and storage section  25  or to access an external database via wireless communication link to determine what traffic rules apply to the location in which the host vehicle  10  is currently located. From this information, the control unit  20  is configured to choose from a plurality of stored values associated with parameters that are used to modify the timing for issuing advisories and warnings. For example, the different values for the minimum gap “d_mingap”, the margin “d_margin” and the hysteresis “d_hysteresis” are stored in the database according to the different traffic laws as shown in  FIG. 7 . If the host vehicle  10  is in a jurisdiction where entering an intersection on a yellow signal is permitted, the control unit  20  is configured to load prescribed values “d_mingap a ”, “d_margin a ” and “d_hysteresis a ” for the minimum gap, the margin and the hysteresis, respectively, to calculate the advisory distance (d_advisory) and the warning distance (d_warning) using the equations (1) and (4). The prescribed values “d_mingap a ”, “d_margin a ” and “d_hysteresis a ” are preferably set in advance to appropriate values. On the other hand, if the host vehicle  10  is located in a jurisdiction where entering an intersection on a yellow signal is not permitted, the control unit  20  is configured to load prescribed values “d_mingap b ”, “d_margin b ” and “d_hysteresis b ” for the minimum gap, the margin and the hysteresis, respectively, to calculate the advisory distance (d_advisory) and the warning distance (d_warning) using the equations (1) and (4). The prescribed values “d_mingap b ”, “d_margin b ” and “d_hysteresis b ” are preferably set in advance to appropriate values so that the advisories and warnings are issued at relatively earlier timings as compared to when the prescribed values “d_mingap a ”, “d_margin a ” and “d_hysteresis a ” are used. If for some reason the control unit  20  is unable to determine what traffic laws apply in the current location of the host vehicle  10 , the control unit  20  is preferably configured to use prescribed values “d_mingap c ”, “d_margin c ” and “d_hysteresis c ” that are set in advance to appropriate values. Alternatively, the control unit  20  can be configured to use the prescribed values “d_mingap b ”, “d_margin b ” and “d_hysteresis b ” as the most conservative values if the control unit  20  is unable to determine what traffic laws apply in the current location of the host vehicle  10 . 
         [0069]    Accordingly, with the on-board vehicle warning system  12  of the illustrated embodiment, the timings at which the advisories and warnings are issued (e.g., the advisory distance (d_advisory) and the warning distance (d_warning)) are appropriately adjusted according to the traffic regulation that is in effect in the current location of the host vehicle  10 . 
         [0070]    Referring back to  FIG. 5 , when the phase of the traffic light in front of the host vehicle  10  is in green, no advisory or warning is issued from the on-board vehicle warning system  12 . When the phase of the traffic light is in yellow, the control unit  20  is configured to determine a potential traffic violation by the host vehicle  10  according to the local traffic regulation. More specifically, the control unit  20  is configured to calculate the distance from the stop bar when the signal turns red (d_red) based on the SPAT information received from the intersection unit  17  and the vehicle travel information such as the current speed (v o ) of the host vehicle  10 . The distance from the stop bar when the signal phase changes to red (d_red) can be calculated according to the equation (9) below. 
         [0000]        d _red= d ( t )− v   0   ·t   y→r   (9)
 
         [0071]    In the equation (9), the value “t y→r ” represents the amount of time left before the signal changes to red, which is determined based on the SPAT information received from the intersection unit  17  via the roadside unit  16 . In the equation (9), the distance from the stop bar (d_red) is calculated so that the value becomes smaller (negative value) as the position of the host vehicle  10  advances further away from the intersection. 
         [0072]    When it is determined that the host vehicle  10  will be able to clear the intersection before the signal phase changes to red if the host vehicle  10  continues to travel at the current speed (v 0 ) (i.e., the distance from the stop bar when the signal turns red (d_red) is beyond the clearance distance (d_clear)), then the control unit  20  does not issue an advisory or a warning. However, when it is determined that the host vehicle  10  will still be traveling within the intersection when the signal phase changes to red if the host vehicle  10  continues to travel at the current speed (v 0 ) (i.e., the distance from the stop bar when the signal turns red (d_red) is not beyond the clearance distance (d_clear)), the host vehicle  10  is required to stop prior to the intersection in order to avoid committing a traffic light violation. Therefore, in such case, the control unit  20  determines whether the host vehicle  10  is taking action to stop or decelerate before the intersection. If the control unit  20  determines that the host vehicle  10  is not taking action to decelerate or stop before the intersection, then the control unit  20  issues the advisory at appropriate timing. More specifically, the advisory is issued at timing when the host vehicle  10  is within the distance (d_advisory) in which it would require the driver to brake at some predetermined level of deceleration in order to come to a stop at the stop bar prior to the intersection. 
         [0073]    When the phase of the traffic light is in red in the example shown in  FIG. 5 , the host vehicle  10  is required to stop at the stop bar in order to avoid committing a traffic light violation. Therefore, the control unit  20  determines whether the host vehicle  10  is stopping. If the control unit  20  determines that the host vehicle  10  is not taking action to stop before the intersection, then the control unit  20  issues the warning at appropriate timing. The warning is issued at timing when the host vehicle  10  is within the distance (d_warning) in which it would require the driver to brake at some predetermined level of deceleration in order to come to a stop at the stop bar prior to the intersection. 
         [0074]    The example as shown in  FIG. 5  is directed to a situation where the host vehicle  10  is located in the jurisdiction in which no offence has been committed as long as the light is yellow when the vehicle enters the intersection. However, as the host vehicle  10  travels across different jurisdictions, the traffic regulation that defines the traffic light violations changes. Thus, the control unit  20  is configured to adjust the advisory/warning parameters for determining the advisory distance (d_advisory) and the warning distance (d_warning) according to the local traffic regulation that is in effect in the current location of the host vehicle  10 . 
         [0075]    Moreover, the control unit  20  can also be configured to adjust calculation process for determining the potential traffic violation by the host vehicle  10  in addition to adjusting the advisory/warning parameters. For example, if the local traffic regulation defines no offence has been committed as long as the light is yellow when the vehicle enters the intersection, then the control unit  20  can be configured to adjust the control flow for determining the potential traffic violation and for issuing the driver notification so that an advisory and/or a warning is issued only when the control unit  20  determines the host vehicle  10  will enter the intersection after the light turns red based on the intersection information and the vehicle travel information. In other words, it may not be necessary to determine whether the host vehicle  10  will be able to clear the intersection by the time the signal turns red since no offence will be committed in such jurisdiction as long as the light is yellow when the vehicle enters the intersection. On the other hand, if the traffic regulation in effect in the current location of the host vehicle  10  defines running a yellow light is an offence, then the control unit  20  is configured to adjust the parameters and/or the control flow for determining the potential traffic violation and for issuing the driver notification so that an advisory and/or a warning is issued to the driver when the control unit  20  determines that the host vehicle  10  will enter the intersection after the light turns yellow based on the intersection information and the vehicle travel information. 
         [0076]    Thus, the on-board vehicle warning system  12  according to the illustrated embodiment is configured and arranged to determine the potential traffic violation and to issue the advisory and/or the warning at appropriate timings according to the local traffic regulation that is in effect in the current location of the host vehicle  10 . 
         [0077]    Referring now to a flowchart of  FIG. 8 , the main control executed by the control unit  20  of the on-board vehicle warning system  12  for alerting the driver of the host vehicle  10  of the potential traffic light violation will be explained. The control flow illustrated in  FIG. 8  is executed when the host vehicle  10  enters within the broadcast range of the roadside unit  16  coupled to the intersection unit  17  as the host vehicle  10  approaches the upcoming intersection. 
         [0078]    In step S 1 , the wireless communication system  21  of the on-board vehicle warning system receives the intersection information relating to the upcoming intersection from the intersection unit  17  via the roadside unit  16 . 
         [0079]    In step S 2 , the control unit  20  is configured to detect the current location of the host vehicle  10  based on the signals received from the global positioning system  23 . 
         [0080]    In step S 3 , the control unit  20  is configured to load advisory/warning parameters corresponding to the local traffic regulation that is in effect in the current location of the host vehicle  10  detected in step S 2 . More specifically, as mentioned above, the control unit  20  is preferably configured to load the minimum gap “d_mingap”, the margin “d_margin” and hysteresis “d_hys” for calculating the advisory distance (d_advisory) and the warning distance (d_warning) corresponding to the local traffic regulation from the table such as one shown in  FIG. 7  stored in the map database and storage section  25  or the external database. 
         [0081]    In step S 4 , the control unit  20  is configured to execute a control for determining a potential traffic light violation and for issuing the driver notification (advisories and/or warnings) using the advisory/warning parameters loaded in step S 3 . 
         [0082]    Referring now to a flowchart of  FIG. 9 , one example of the control processing executed in step S 4  of  FIG. 8  for determining the potential traffic violation and issuing the advisory and/or the warning will be explained in accordance with the illustrated embodiment. In this example, it is assumed that the host vehicle  10  is located in the jurisdiction in which the traffic regulation defines that an offence occurs if the light turns red at any time before the vehicle clears the intersection. 
         [0083]    In step S 10  of  FIG. 9 , the control unit  20  is configured to calculate values corresponding to the width of the intersection (w_intersection), the advisory distance (d_advisory), the warning distance (d_warning), the distance to the stop bar (d(t)) and the clearance distance (d_clear) as explained above with reference to  FIG. 5 . 
         [0084]    In step S 20 , the control unit  20  is configured to determine whether the current phase of the traffic light is in yellow based on the intersection information received from the intersection unit  17  via the roadside unit  16 . If the current phase of the traffic light is in yellow (Yes in step S 20 ), then the control unit  20  proceeds to step S 100 . On the other hand, if the current phase of the traffic light is not in yellow (No in step S 20 ), then the control unit  20  proceeds to step S 30 . 
         [0085]    In step S 30 , the control unit  20  is configured to determine whether the current phase of the traffic light is in red based on the intersection information received from the intersection unit  17  via the roadside unit  16 . If the current phase of the traffic light is in red (Yes in step S 30 ), then the control unit  20  proceeds to step S 50 . On the other hand, if the current phase of the traffic light is not in red (No in step S 30 ), then the control unit  20  proceeds to step S 40 . 
         [0086]    In step S 40 , the control unit  20  is configured to update the SPAT information based on the updated intersection information received from the intersection unit  17  via the roadside unit  16 . Also, the control unit  20  is configured to update the vehicle travel information based on the current vehicle travel condition detected by the vehicle information detecting section. Then, the control unit  20  returns to step S 20 . 
         [0087]    In step S 50 , the control unit  20  is configured to determine whether the current distance between the host vehicle  10  and the stop bar (d(t)) is equal to or smaller than the warning distance (d_warning). If the distance to the stop bar (d(t)) is larger than the warning distance (d_warning) (No in step S 50 ), then the control unit  20  proceeds to step S 60 . 
         [0088]    In step S 60 , the control unit  20  is configured to recalculate (update) the distance to the stop bar (d(t)), and then to return to step S 30 . 
         [0089]    On the other hand, if the distance to the stop bar (d(t)) is equal to or smaller than the warning distance (d_warning) (Yes in step S 50 ), then the control unit  20  proceeds to step S 70 . 
         [0090]    In step S 70 , the control unit  20  is configured to determine whether the host vehicle  10  is taking action to decelerate or stop before the intersection based on the vehicle travel information. Whether the host vehicle  10  is taking action or not is preferably determined by monitoring both the detection signals from the throttle position and the brake lamp switch. If the throttle position is reduced or if the brake lamp switch is activated, the control unit  20  interprets these inputs as the driver of the host vehicle  10  at least being aware of the traffic situation. If the control unit  20  determines that the host vehicle  10  is taking action to decelerate or stop before the intersection (Yes in step S 70 ), then the control unit  20  proceeds to step S 80 . 
         [0091]    In step S 80 , the control unit  20  is configured to determine whether the host vehicle  10  has stopped. If the control unit  20  determines that the host vehicle  10  has stopped (Yes in step S 80 ), the control unit  20  ends the current control cycle. On the other hand, if the control unit  20  determines that the host vehicle  10  has not stopped (NO in step S 80 ), then the control unit  20  proceeds to step S 40  where the SPAT information and the vehicle travel information are updated before the control processing returns to step S 20 . 
         [0092]    On the other hand, if the control unit  20  determines that the host vehicle  10  is not taking any action to decelerate or stop before the intersection (No in step S 70 ), then the control unit  20  proceeds to step S 90 . 
         [0093]    In step S 90 , the control unit  20  is configured to issue a warning to the driver of the host vehicle  10 . Then, the control unit  20  ends the current control cycle. 
         [0094]    Referring back to step S 20 , if the control unit  20  determines that the current phase of the signal is in yellow (Yes in step S 20 ), the control unit  20  proceeds to step S 100 . 
         [0095]    In step S 100 , the control unit  20  is configured to calculate a distance from the stop bar when the signal phase changes to red (d_red) as explained above with reference to  FIG. 5 . 
         [0096]    In step S 110 , the control unit  20  is configured to determine whether the distance from the stop bar when the signal phase changes to red (d_red) is equal to or smaller than the clearance distance (d_clear). If the control unit  20  determines that the distance from the stop bar when the signal phase changes to red (d_red) is equal to or smaller than the clearance distance (d_clear) (Yes in step S 110 ), the host vehicle  10  is able to clear the intersection before the signal turns red. Therefore, the control unit  20  ends the control processing of the current cycle. On the other hand, if the control unit  20  determines that the distance from the stop bar when the signal phase changes to red (d_red) is larger than the clearance distance (d_clear) (No in step S 110 ), the host vehicle  10  will not be able to exit the intersection before the signal turns red, and thus, the control unit  20  proceeds to step S 120 . 
         [0097]    In step S 120 , the control unit  20  is configured to determine whether the distance to the stop bar (d(t)) is equal to or smaller than the advisory distance (d_advisory). If the control unit  20  determines that the distance to the stop bar (d(t)) is larger than the advisory distance (d_advisory) (No in step S 120 ), then the control unit  20  proceeds to step S 130  to calculate the updated distance to the stop bar (d(t)), and to step S 40  where the SPAT information and the vehicle travel information are updated before the control processing returns to step S 20 . 
         [0098]    On the other hand, if the control unit  20  determines that the distance to the stop bar (d(t)) is equal to or smaller the advisory distance (d_advisory) (Yes in step S 120 ), then the control unit  20  proceeds to step S 140 . 
         [0099]    In step S 140 , the control unit  20  is configured to determine whether the host vehicle  10  is taking action to decelerate or stop before the intersection based on the vehicle travel information. Whether the host vehicle  10  is taking action or not is preferably determined by monitoring both the detection signals from the throttle position and the brake lamp switch. If the throttle position is reduced or if the brake lamp switch is activated, the control unit  20  interprets these inputs as the driver of the host vehicle  10  at least being aware of the traffic situation. If the control unit  20  determines that the host vehicle  10  is taking action to decelerate or stop before the intersection, then the control unit proceeds to step S 80 . On the other hand, if the control unit  20  determines that the host vehicle  10  is not taking any action to decelerate or stop before the intersection, then the control unit  20  proceeds to step S 150 . 
         [0100]    In step S 150 , the control unit  20  is configured to check if an advisory has already been issued previously in the current control cycle. If the advisory has already been issued (Yes in step S 150 ), then the control unit  20  proceeds to step S 40  where the SPAT information and the vehicle travel information are updated before the control processing returns to step S 20 . On the other hand, if the advisory has not been issued yet (No in step S 150 ), then the control unit  20  proceeds to step S 160 . 
         [0101]    In step S 160 , the control unit  20  is configured to issue an advisory to the driver. Then, the control unit  20  proceeds to step S 40  where the SPAT information and the vehicle travel information are updated before the control processing returns to step S 20 . 
         [0102]    The control flow illustrated in  FIG. 9  is explained as being executed by the control unit  20  in step S 4  of  FIG. 8  when the host vehicle  10  is located in the jurisdiction where a traffic light violation occurs if the light turns red at any time before the host vehicle  10  clears the intersection. As the host vehicle  10  travels across different jurisdictions, the control unit  20  is configured to adjust the advisory/warning parameters (e.g., load the new parameters) corresponding to the current jurisdiction. In addition, the control unit  20  can be configured to adjust the control flow for determining the potential traffic violation and producing the driver notification in step S 4  of  FIG. 8  to be commensurate with the local traffic regulation that is in effect in the current location of the host vehicle  10 . For example, the control flow illustrated in  FIG. 9  may be used in the jurisdiction where no offence has been committed as long as the light is yellow when the vehicle enters the intersection by merely adjusting the parameter for determining the potential traffic violation and producing the driver notification (e.g., setting the clearance distance (d_clear) to a smaller value). Moreover, the control unit  20  can be configured to modify the control flow illustrated in  FIG. 9  to adapt the calculations for determining the potential traffic violation to the local traffic regulation. 
         [0103]    In the illustrated embodiment explained above, the control unit  20  is configured to issue the driver notification (an advisory and/or a warning) when the control unit  20  detects the potential traffic violation by the host vehicle  10 . In addition, the control unit  20  can be configured to apply a preemptive vehicle control for decelerating the host vehicle  10 , such as controlling the brake system to automatically brake the host vehicle  10 , in order to prevent the host vehicle  10  from committing a traffic violation. 
       General Interpretation of Terms 
       [0104]    In understanding the scope of the present invention, the term “configured” as used herein to describe a section, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, sections, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, sections, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. As used herein to describe the present invention, the following directional terms “forward, rearward, above, downward, vertical, horizontal, below and transverse” as well as any other similar directional terms refer to those directions of a vehicle equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a vehicle equipped with the present invention as used in the normal riding position. 
         [0105]    While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.