Patent Publication Number: US-6218963-B1

Title: Time management system for passing vehicles

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a passing vehicle time management system, and more particularly to a passing vehicle time management system suitable for the time management of vehicles passing a tollhouse on a toll road or the like by using communication units. 
     In a conventional system, a driver (user) of a vehicle running on a toll road or the like receives a road ticket from a toll collector or an automatic ticket dispenser at the tollhouse, and after the driver reaches the target exit, the driver pays the toll at the tollhouse directly to the toll collector or automatic toll receiving machine. For the toll transfer process at the tollhouse on a toll road or the like, the toll corresponding to each road ticket is checked for each vehicle and the same vehicle is not incurred the toll twice. With such a system, however, it takes a time to process the toll transfer so that traffic congestion may occur at the tollhouse. 
     To solve such problems, an automatic toll transfer system has been adopted. This automatic toll transfer system incorporates the configuration that a fixed station serving as a fixed communication unit is provided at a tollhouse on a toll road or the like, a vehicles running along the toll road is equipped with a mobile station serving as a mobile communication unit, and the toll is automatically transferred by exchanging information on the toll transfer between the fixed station and mobile station through wireless communications. For example, in this system, information on an entrance tollhouse and an exit tollhouse, information on a toll transfer and the like are exchanged through wireless communications, and the toll is calculated at the fixed station and incurred to the bank account or the like of a user (driver). Manual toll calculation and charge process are therefore unnecessary and the man power can be reduced. Still more, a time zone is set during which the communications from the mobile station to the fixed station is inhibited for a predetermined time (release timer time) after the toll transfer information is exchanged between the mobile and fixed stations. Therefore, during the predetermined time after the communication completion, it is possible to prevent the fixed station from issuing a communication link request to the mobile station and executing a charging process twice. 
     The conventional automatic toll transfer system, however, does not consider the case wherein a vehicle in an area communicable with the fixed station may stay long because of traffic congestion. If the vehicle stays in the area communicable with the fixed station after the mobile station mounted on the vehicle exchanges the toll transfer information with the fixed station, there is a possibility that after the predetermined time after the completion of communications with the fixed station, i.e., after the release timer counts up, the mobile station may respond to a communication link request from the fixed station and resume communications. In such a case, unnecessary communications are performed between the mobile and fixed stations and the communications may become congested. Furthermore, as the communications between the mobile and fixed stations resume, there is a possibility that the charging process for incurring the toll is executed twice for the same vehicle. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a passing vehicle time management system capable of dynamically setting a release timer time in accordance with a vehicle passing time or speed which is used as a traffic flow index, and preventing communication congestion to be otherwise caused by the running states of vehicles. 
     In order to achieve the above object, the invention provides a time management system for passing vehicles using a passing time of a vehicle as a traffic flow index. The time management system comprises: mobile communication means mounted on a vehicle; fixed communication means for transferring toll transfer information to and from the mobile communication means mounted on the vehicle when the vehicle enters a communicable area; passing time measuring means for measuring a passing time of the vehicle passing a vehicle measuring section partially including a road belonging to the communicable area; and timer time setting means for setting a release timer time in accordance with a value measured by the passing time measuring means and adding the set release timer time to the toll transfer information, the release timer time indicating a communication inhibition time after completion of transfer of the toll transfer information, wherein the mobile communication means stops communication with the fixed communication means for the release timer time added to the toll transfer information after the completion of transfer of the toll transfer information to and from the fixed communication means, even if a communication link request is received from the fixed communication means. 
     The invention also provides a time management system for passing vehicles using a passing speed of a vehicle as a traffic flow index. The time management system comprising: mobile communication means mounted on a vehicle; fixed communication means for transferring toll transfer information to and from the mobile communication means mounted on the vehicle when the vehicle enters a communicable area; passing speed measuring means for measuring a passing speed of the vehicle passing a vehicle measuring section partially including a road belonging to the communicable area; and timer time setting means for setting a release timer time in accordance with a value measured by the passing speed measuring means and adding the set release timer time to the toll transfer information, the release timer time indicating a communication inhibition time after completion of transfer of the toll transfer information, wherein the mobile communication means stops communication with the fixed communication means for the release timer time added to the toll transfer information after the completion of transfer of the toll transfer information to and from the fixed communication means, even if a communication link request is received from the fixed communication means. 
     In each of the passing vehicle time management systems, the fixed communication means may be means having a function of transferring toll transfer information to and from the mobile communication means mounted on the vehicle when the vehicle enters one of a plurality of divided communicable areas, and the passing time measuring means or passing speed measuring means may be means having a function of measuring a passing time or speed of the vehicle passing a vehicle measuring section partially including a road belonging to each of the plurality of divided communicable areas. 
     In each of the passing vehicle time management system, the following feature may be added. 
     The fixed communication means starts the transfer of the toll transfer information to and from the mobile communication means mounted on the vehicle and judges that communication is duplicate communication to a same vehicle in the communicable area, the fixed communication means forcibly stops the communication with the same vehicle. 
     With the above-described means, the release timer time is set in accordance with the measured passing time or speed of the vehicle passing the vehicle measuring section. Accordingly, if the vehicle passing time prolongs or the vehicle passing speed lowers because of the traffic congestion, the release timer time prolongs. It is therefore possible to prevent communication congestion to be caused by unnecessary communications between the mobile communication means and fixed communication means after the completion of exchange of the toll transfer information between the mobile communication means and fixed communication means, and to prevent the process of charging a toll to the same vehicle twice. 
     If duplicate communication is performed with the same vehicle in the communicable region after the predetermined time after the completion of transfer of the toll transfer information between the mobile communication means mounted on the vehicle and the fixed communication means, the communication with the same vehicle is forcibly stopped. It is therefore possible to reliably prevent the duplicate toll charging process to the same vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the overall configuration of a system according to an embodiment of the invention. 
     FIG. 2 is a block diagram showing the structure of a fixed station. 
     FIG. 3 is a flow chart illustrating a method of updating a release timer value. 
     FIG. 4 is a diagram showing the structure of a vehicle passing time management table. 
    
    
     DESCRIPTION OF THE EMBODIMENT 
     An embodiment of the invention will be described with reference to the accompanying drawings. FIG. 1 shows the overall configuration of a system according to an embodiment of the invention. Referring to FIG. 1, a fixed station  10  is installed at a tollhouse on a superhighway or the like, and a tollhouse island  14  is disposed along a road  12 . Along the tollhouse island  14 , vehicle detectors  16  and  18 , a road display device  10 , a departure control machine  22 , and a vehicle detector  24  are dispsersively disposed in this order from the entrance side. A tollhouse antenna  26  is disposed above the vehicle detector  18 . The vehicle detectors  16  and  18 , road display device  10 , departure control machine  22 , vehicle detector  24  and antenna  26  are electrically connected to the fixed station  10  which is connected to an upper level data processing apparatus. A vehicle  28  running on the road  12  is equipped with a mobile station  30  serving as a mobile communication unit. 
     The fixed station  10  serves as a fixed communication unit together with the antenna  26 , and also serves as a passing time measuring unit or a passing speed measuring unit, and as a timer setting unit, together with the vehicle detectors  16  and  24 . 
     More specifically, as shown in FIG. 2, the fixed station  10  has an external signal output unit  32 , an external signal input unit  34 , a communication control unit  36 , a wireless transmitter unit  38 , a wireless communication control unit  40 , a control unit  42 , and a memory unit  44 . The external signal output unit  32  is connected to the display device  20  and departure control machine  22 . The external signal input unit  34  is connected to the vehicle detectors  16  and  18 , departure control machine  22  and vehicle detector  24 . the communication control unit  36  is connected to an upper level data processing apparatus. The wireless transmitter unit  38  is connected to the tollhouse antennal  26 . The control unit  42  has a built-in timer. The memory unit  44  stores data related to a release timer time and a vehicle passing time management table. 
     The tollhouse antenna  26  transmits information supplied from the fixed station  10  in a predetermined area in the form of radio waves. The vehicle detectors  16  and  18  are installed at opposite ends of a communicable area allowing information exchange between the mobile station  30  mounted on the vehicle  28  and the antenna  26  through wireless communications. Namely, the vehicle detector  16  detects that the vehicle  28  enters the communicable area of the tollhouse, and supplies this detection signal to the fixed station  10 . The vehicle detector  18  detects that the vehicle  28  enters the communicable area exits this area, and supplies this detection signal to the fixed station  10 . By using as a trigger the detection signal supplied from the vehicle detector  16 , the fixed station  10  starts exchanging the toll transfer information with the mobile station, and by using as a trigger the detection signal supplied from the vehicle detector  18 , the fixed station  10  operates to display the process result on the display device  20 . 
     As the detection signal is input from the vehicle detector  16  to the fixed station  10 , this detection signal is input via the external signal input unit  34  to the control unit  42 . The control unit  42  executes a vehicle tollhouse entrance/exit management (entrance) process as a process of giving an entered vehicle process ID and a current time, and stores this process result in the memory unit  44 . In addition, by using as a trigger the detection signal of the vehicle detector  16 , the fixed station  10  transmits information to the mobile station  30  via the wireless communication control unit  40 , wireless transmitter unit  38  and antenna  26 . The information includes: the toll transfer information such as entrance information (tollhouse name) and subscriber information (bank account of the drive of the vehicle  28 ); and information on a release timer time indicating a communication inhibition time after the completion of exchange of the toll transfer information with the mobile station  30 . After the completion of necessary information exchange between the fixed station  10  and mobile station  30 , the mobile station  30  executes a process of inhibiting to resume communications for a predetermined time after the communication completion of the toll transfer information, i.e., during the release timer time. 
     As the vehicle  28  further runs and is detected with the vehicle detector  18 , this detection signal is input to the fixed station  10 . This detection signal is supplied via the external signal input unit  34  to the control unit  42 . By using as a trigger the detection signal from the vehicle detector  18 , the control unit  42  operates to display a toll calculation result, a passing permission/denial judgement result and the like on the display device  20  via the external signal output unit  32 . The control unit  42  further operates to open or close the departure control machine  22  via the external signal output unit  32 , in accordance with the passing permission/denial judgement result. For example, if the passing of the vehicle  28  is to be denied, the departure control machine  22  is controlled to lower a passing denial bar to prevent the passing of the vehicle  28 . During the opening operation of the departure control machine  22 , the vehicle  28  continues running and when it is detected with the vehicle detector  24 , this detection signal is input via the external signal input unit  34  to the control unit  42 . In this case, the control unit  42  operates to erase the data related to the vehicle  28  and displayed on the display device  20 , to close the departure control machine  22 , and to execute a vehicle tollhouse entrance/exit (exit) process. In this manner, after the toll transfer information exchange between the mobile station  30  and fixed station  10  is completed while the vehicle  28  continues running along the tollhouse, the release timer time lapses. Thereafter, the mobile station  30  mounted on the vehicle  28  can start communicating with another fixed station at the next tollhouse, upon reception of a communication link request. 
     The release timer time for the vehicle  28  is set by considering the running states of other vehicles. For example, if it takes a long time for the vehicle to pass the tollhouse because of traffic congestion, the fixed station  10  sets a longer release timer time to each vehicle in accordance with an average of passing times of other vehicles, as will be later described. It is therefore possible to prevent the fixed station  10  from issuing the communication link request to the mobile station  30  in the communicable area, after the lapse of the release timer time. Even if a longer release timer time is set, the mobile station  30  of the vehicle  28  in the communication area can receive the communication link request from the fixed station  10  after the lapse of the release timer time, depending upon the traffic congestion. In view of this, according to the embodiment, if the mobile station  30  in the communicable area receives a communication link request from the fixed station  10  after the lapse of the release timer time, although the communication starts once, this communication with the mobile station is forcibly stopped by the process of the control unit  42  of the fixed station  10 . Namely, if the mobile station  30  in the communicable area receives a communication link request from the fixed station  10  after the lapse of the release timer time, although the communication starts once, during this communication start period, information is exchanged between the fixed station  10  and mobile station  30 , for example, the information including cryptography information used by the vehicle  28  and vehicle-mounted unit information (e.g., information for identifying the vehicle). The vehicle-mounted unit information transmitted from the mobile station  30  to the fixed station  10  contains a vehicle-mounted unit ID for identifying the vehicle. The control unit  42  checks this vehicle-mounted unit ID. If the vehicle  28  having this vehicle-mounted unit ID does not still exit from the tollhouse, it is judged that the communication with the vehicle  28  is duplicate, and the communication with the mobile station  30  is forcibly stopped. With this process, it is possible to prevent duplicate toll charging to the same vehicle  28  and to prevent communication congestion. 
     Next, a method of setting the release timer value will be described with reference to FIGS. 3 and 4. 
     First, as the vehicle  28  enters the tollhouse and the entrance of the vehicle  28  is detected with the vehicle detector  16  (step S 1 ), the control unit  42  determines the entered vehicle process ID for identifying the vehicle  28  and fetches the entered vehicle process ID and current time (Step S 2 ), thereafter stores this data in a vehicle passing time management table  44  in the memory unit  44 , and turns on a tollhouse stay flag while the vehicle  28  stays at the tollhouse (Step S 3 ). Thereafter, the toll transfer information is exchanged between the mobile station  30  of the vehicle  28  and the fixed station  10 . During these processes, the vehicle  28  continues running and when the entrance of the vehicle  28  is detected with the vehicle detector  24  (Step S 4 ), the control unit  42  fetches the current time from a timer and stores the current time data in the vehicle passing time management table  46  (Step S 5 ). At this time, the control unit  42  calculates the time and speed taken by the vehicle  28  to pass a section between the vehicle detectors  16  and  24 , stores the calculation results in the vehicle passing time management table  46  and turns off the tollhouse stay flag (Step S 6 ), to mark that the vehicle exited from the tollhouse (Step S 7 ). 
     The control unit  42  updates the release timer time (value) in accordance with the passing times and speeds of other vehicles measured as the two traffic flow indices. The passing time and speed of each vehicle is measured in a vehicle measuring section between the vehicle detectors  16  and  24 , i.e., the vehicle measuring section partially including the road in the communicable area of the fixed station  10  and mobile station  30 . 
     In updating the release timer time in accordance with the passing times and speeds of other vehicles in the vehicle measuring section, the following calculation equation is used. 
     For example, the update calculation equation for the release timer value RLT is represented by: 
     
       
         RLT=RLTs×(C1×Tav/Ts)  (1) 
       
     
     where 
     RLTs: an initial set value (a value set in accordance with the vehicle measuring section passing time at a vehicle speed A); 
     C1: an adjustment parameter; 
     Tav: an average of vehicle passing times stored in the vehicle passing time management table  46  during a timer period; and 
     Ts: a vehicle measuring section passing time at a vehicle speed A. 
     The important factor in the equation (1) is the vehicle passing time index Tav. 
     This equation (1) is an update calculation equation for the release timer value using the passing time. The release timer value may be updated by using the vehicle passing speed as the traffic flow index. 
     For example, Vav (an average of vehicle passing speeds stored in the vehicle passing time management table  46  during a timer period) may be used in place of Tav in the equation (1), and Vs (a vehicle measuring section passing speed) may be used in place of Ts in the equation (1). In this case, the equation (1) is replaced by the following equation (2): 
     
       
         RLT=RLTs×(C2×Vs/Vav)  (2) 
       
     
     In the above-described equations, the average passing time and speed in the timer period are used. Instead, the passing time and speed in the timer period may be extrapolated relative to the time axis. 
     A dynamic timer value may be determined by modifying the equation (1) as in the following: 
     
       
         RLT=RLTs+(C3×Tav/Ts)  (3) 
       
     
     
       
         RLT=RLTs+(C4×Vs/Tav)  (4) 
       
     
     In the equations (3) and (4), the definition of each parameter is the same as that for the equations (1) and (2), and replacement of the passing time index by the passing speed index is also the same as that for the equations (1) and (2). 
     Moving averages Tmav and Vmav of passing times and speeds in the timer period may also be used as in the following equations: 
     
       
         RLT=C5+Tmav or RLT=C6×Tmav  (5) 
       
     
     
       
         RLT=C7(C8−Vmav) or RLT=C9/Vmav  (6) 
       
     
     In the equations (5) and (6), C7, C8 and C9 are adjustment parameters like those C1 to C4. 
     As described above, the most important factor in each of the various equations is the passing time or speed of a vehicle passing the vehicle measuring section. 
     In the above embodiment, the passing time and speed of a vehicle passing the vehicle measuring section is calculated by using the detection signals of the vehicle detectors  16  and  24 . Instead, any twos of the vehicle detectors  16 ,  18  and  24  may be used to calculate the passing time and speed of a vehicle passing the section between the twos. 
     In this embodiment, although the entrance of a vehicle is used as the detection timing of the vehicle detectors  16 ,  18  and  24 , the exit of a vehicle may be used or a combination thereof may also be used. 
     In the above embodiment, a single communicable area between the mobile station  30  and fixed station  10  is used. Instead, the single communicable area between the mobile station  30  and fixed station  10  may be divided into a plurality of communicable areas. In this case, toll transfer information is exchanged between the fixed station  10  and mobile station  30  when a vehicle enters one of the plurality of divided communicable areas, and the fixed station  10  measures the passing time or speed of each vehicle taken to pass a vehicle measuring section partially including the road belonging to each of the plurality of divided communicable areas. In this manner, the advantageous effects similar to the embodiment described above can be obtained. 
     According to the embodiment, the passing time and velocity of each vehicle passing the vehicle measuring section are measured by using two vehicle detectors provided to an automatic toll transfer system along a toll road and the like, and in accordance with the measured passing time or speed, the release timer value is updated. Accordingly, without adding new apparatus, the passing time and speed of a vehicle passing the vehicle measuring section can be established as the traffic flow indices in accordance with the detection signals of the two vehicle detectors, and the release timer value can be dynamically set.