Patent Publication Number: US-11396313-B2

Title: Traffic system, control method, and program

Description:
TECHNICAL FIELD 
     The present invention relates to a travel control device, a vehicle, a traffic system, a control method, and a program. 
     Priority is claimed on Japanese Patent Application No. 2014-010399, filed Jan. 23, 2014, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     In order for safe driving of a train, there is a railway system including an automatic train protection (ATP) device that automatically operates a brake when the speed of the train exceeds a predetermined speed. In addition, there is also a railway system including an automatic train operation (ATO) device for the purpose of automatic operation and an energy saving operation of the train. 
     Patent Document 1 describes a technology that includes both the ATP device and the ATO device and realizes automatic operation of a train that allows safely stopping and does not cause an operation delay as a related technology. 
     CITATION LIST 
     Patent Document 
     [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2010-28926 
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, in a railway system, each of ATP and ATO has independent functions and thus, an ATP device and an ATO device are usually separate from each other as hardware devices. Therefore, a railway system including both an ATP device and an ATO device is designed to have a margin which is a sum of a maximum value of a recognition position error of the ATP device and a maximum value of a recognition position error of the ATO device. In addition, since each of the ATP device and the ATO device calculates positions, even in the railway system the railway system using the technology described in Patent Document 1, the railway system is designed to have a margin which is a sum of each of the maximum values of the recognition position errors. As a result thereof, when automatic driving is performed on a vehicle, the margin cannot be smaller than the sum of the maximum values of the recognition position errors, and thus, there is a possibility that the travelling time of the train with respect to a travelling distance may increase. 
     The present invention provides a travel control device, a vehicle, a traffic system, a control method, and a program that can reduce the travelling time of the train with respect to the travelling distance when automatic driving is performed on the vehicle using the travel control device. 
     Solution to Problem 
     According to a first aspect of the present invention, a travel control device is mounted on a vehicle and sets a travel speed according to a position of the vehicle and causes the vehicle to travel. The travel control device includes a limit information acquisition unit, a current position acquisition unit, a current speed acquisition unit, a travel curve generation unit, and a speed command unit. The limit information acquisition unit is configured to acquire limit information which indicates a plurality of relative positions to the front position with a current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions, from the vehicle speed limit unit that is configured to set the speed limits at a plurality of positions in order to achieve a predetermined deceleration completion speed at the speed limit start position. The current position acquisition unit is configured to acquire a current position of the vehicle. The current speed acquisition unit is configured to acquire a current speed of the vehicle. The travel curve generation unit is configured to generate a travel curve in which the speed limit at each position obtained from the limit information becomes lower than a predetermined speed, according to the acquired limit information, the current position, and the current speed. The speed command unit is configured to generate a speed command according to the generated travel curve and the current position. 
     According to a second aspect of the present invention, the limit information acquisition unit included in the travel control device acquires the limit information which includes a plurality of relative positions up to the front position with the current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions as a sequence. The travel curve generation unit included in the travel control device generates the travel curve according to the limit information. 
     According to a third aspect of the present invention, the limit information acquisition unit included in the travel control device acquires limit information including only the sequence with respect to the representative speed among the sequence of the relative positions from the current position to the front position. The travel curve generation unit included in the travel control device generates the travel curve according to the limit information. 
     According to a fourth aspect of the present invention, the limit information acquisition unit included in the travel control device acquires the limit information including the relative position from the current position to a deceleration completion position, the speed, and a guaranteed deceleration. The travel curve generation unit included in the travel control device generates the travel curve according to the limit information. 
     According to a fifth aspect of the present invention, a vehicle includes a vehicle speed limit unit and a travel control device. The vehicle speed limit unit is configured to set a speed limit at each position in order to achieve a predetermined deceleration completion speed at the speed limit start position. The travel control device includes a limit information acquisition unit, a current position acquisition unit, a current speed acquisition unit, travel curve generation unit, and a speed command unit. The limit information acquisition unit is configured to acquire limit information which indicates a plurality of relative positions to the front position with a current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions, from the vehicle speed limit unit. The current position acquisition unit is configured to acquire a current position of the vehicle. The current speed acquisition unit is configured to acquire the current speed of the vehicle. The travel curve generation unit is configured to generate a travel curve in which the speed limit at each position obtained from the limit information becomes lower than a predetermined speed, according to the acquired limit information, the current position, and the current speed. The speed command unit is configured to generate a speed command according to the generated travel curve and the current position. 
     According to a sixth aspect of the present invention, a traffic system includes the vehicle and a ground ATP device. The vehicle includes a vehicle speed limit unit, a limit information acquisition unit, and a travel control device. The travel control device includes a current position acquisition unit, a current speed acquisition unit, a travel curve generation unit, and a speed command unit. The vehicle speed limit unit is configured to set a speed limit at each position in order to achieve a predetermined deceleration completion speed at the speed limit start position. The limit information acquisition unit is configured to acquire limit information which indicates a plurality of relative positions to the front position with a current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions, from the vehicle speed limit unit. The current speed acquisition unit is configured to acquire a current speed of the vehicle. The travel curve generation unit is configured to generate a travel curve in which the speed limit at each position obtained from the limit information becomes lower than a predetermined speed, according to the acquired limit information, the current position, and the current speed. The speed command unit is configured to generate a speed command according to the generated travel curve and the current position. The ground ATP device outputs the speed limit start position to the vehicle speed limit unit. 
     According to a seventh aspect of the present invention, a control method of a travel control device that is mounted on a vehicle and sets a travel speed according to a position of the vehicle and causes the vehicle to travel. The method includes: causing a limit information acquisition unit of the travel control device to acquire limit information which indicates a plurality of relative positions to the front position with a current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions, from the vehicle speed limit unit of the travel control device that sets the speed limits at a plurality of positions in order to achieve a predetermined deceleration completion speed at the speed limit start position; causing a current position acquisition unit of the travel control device to acquire a current position of the vehicle; causing a current speed acquisition unit of the travel control device to acquire a current speed of the vehicle; causing a travel curve generation unit of the travel control device to generate a travel curve in which the speed limit at each position obtained from the limit information becomes lower than a predetermined speed, according to the acquired limit information, the current position, and the current speed; and causing a speed command unit of the travel control device to generate a speed command according to the generated travel curve and the current position. 
     According to an eighth aspect of the present invention, a program causes a computer in a travel control device, which is mounted on a vehicle and sets a travel speed according to a position of the vehicle and causes the vehicle to travel, to function as: limit information acquisition means for acquiring limit information which indicates a plurality of relative positions to the front position with a current position as a reference and each speed limit information at the front position indicated by each of the plurality of relative positions, from the vehicle speed limit unit of the travel control device that sets the speed limits at a plurality of positions in order to achieve a predetermined deceleration completion speed at the speed limit start position; current position acquisition means for acquiring a current position of the vehicle; current speed acquisition means for acquiring a current speed of the vehicle; travel curve generation means for generating a travel curve in which the speed limit at each position obtained from the limit information becomes lower than a predetermined speed, according to the acquired limit information, the current position, and the current speed; and speed command means for generating a speed command according to the generated travel curve and the current position. 
     Advantageous Effects of the Invention 
     According to the travel control device, the vehicle, the traffic system, the control method, and the program described above, it is possible to reduce the travelling time of the train with respect to the travelling distance when the automatic driving is performed on the vehicle using the travel control device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an example of a traffic system including a travel control device according to a first embodiment of the present invention. 
         FIG. 2  is a diagram showing an example of limit information acquired by a limit information acquisition unit according to the first embodiment from a vehicle speed limit unit. 
         FIG. 3  is a diagram showing an example of a travel curve generated by the travel control device according to the first embodiment. 
         FIG. 4  is a diagram showing an example of a processing flow of the traffic system including the travel control device according to the first embodiment of the present invention. 
         FIG. 5  is a diagram showing an example of a processing flow of the traffic system including a travel control device according to the second embodiment of the present invention. 
         FIG. 6  is a diagram showing an example of a travel curve generated by the travel control device according to the second embodiment of the present invention. 
         FIG. 7  is a diagram showing an example of a processing flow of the traffic system including a travel control device according to a third embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments will be described with reference to the drawings. 
     First, the first embodiment will be described. 
       FIG. 1  is a diagram showing an example of a traffic system  1  including a travel control device  3  according to a first embodiment of the present invention. 
     As shown in  FIG. 1 , the traffic system  1  according to the first embodiment includes a vehicle  2  and a ground automatic train protection (ATP) device  200 . 
     The vehicle  2  includes a travel control device  3  according to the first embodiment and a vehicle speed limit unit  100 . 
     The travel control device  3  is an automatic train operation (ATO) device, and includes a limit information acquisition unit  101 , a current position acquisition unit  102 , a current speed acquisition unit  103 , a travel curve generation unit  104 , and a speed command unit  105 . In addition, the vehicle speed limit unit  100  is an on-vehicle ATP device. 
     The ground ATP device  200  is provided on the ground and transmits a speed limit start position and limit information to the vehicle speed limit unit  100 . The limit information includes speed limit information and position information corresponding to the speed limit. 
     The vehicle speed limit unit  100  acquires the speed limit start position and the limit information from the ground ATP device  200 . In addition, the vehicle speed limit unit  100  acquires a current speed of the vehicle  2  from a speedometer included in the vehicle  2 . The vehicle speed limit unit  100  sets a speed limit at each of a plurality of positions according to the acquired speed limit start position in order to achieve a predetermined deceleration completion speed at the speed limit start position. The vehicle speed limit unit  100  outputs the acquired limit information to the limit information acquisition unit  101 . 
     The limit information acquisition unit  101  acquires the limit information which is form from the speed limit information and the position information corresponding to the speed limit from the vehicle speed limit unit  100 . The limit information acquisition unit  101  outputs the acquired limit information to the travel curve generation unit  104 . 
     The current speed acquisition unit  103  acquires the current speed of the vehicle  2  from the speedometer included in the vehicle  2 . The current speed acquisition unit  103  outputs the acquired current speed to the current position acquisition unit  102  and the travel curve generation unit  104 . 
     The current position acquisition unit  102  acquires the speed limit start position from the ground ATP device  200 . The current position acquisition unit  102  calculates a current position according to an accumulation value of the acquired speed limit start position and the current speed input from the current speed acquisition unit  103 . The current position acquisition unit  102  outputs the calculated current position to the travel curve generation unit  104  and the speed command unit  105 . 
     The travel curve generation unit  104  generates a travel curve that satisfies the speed limit at each position obtained from the limit information according to the input limit information, the current position, and the current speed. The travel curve is a curve that indicates a relationship between the speed and the distance. The travel curve generation unit  104  outputs the generated travel curve to the speed command unit  105 . 
     The speed command unit  105  generates a speed command according to the input travel curve and the current position. The speed command unit  105  outputs the speed command to a control unit that controls the speed of the vehicle  2 . 
       FIG. 2  is a diagram showing an example of the limit information acquired by the limit information acquisition unit  101  according to the first embodiment from the vehicle speed limit unit  100 . 
     The vehicle speed limit unit  100  outputs a state of a speed limit curve that indicates the relationship between the speed and the distance represented by the limit information to the limit information acquisition unit  101  as a sequence of the relative positions from the current position. In addition, at this time, the vehicle speed limit unit  100  outputs a position having a margin of maximum position error with respect to the predicted current position to the current position acquisition unit  102  as the current position. 
     Generally, the speed limit curve is expressed as Equation (1) using an idle running time Td (a time interval from a time when the vehicle speed limit unit  100  recognizes the excessive speed to a time until a brake starts working) and a guaranteed deceleration β in which the deceleration of the train is guaranteed even in a worst situation. 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       x 
                       atp 
                     
                     ⁡ 
                     
                       ( 
                       v 
                       ) 
                     
                   
                   = 
                   
                     
                       x 
                       b 
                     
                     - 
                     
                       
                         ( 
                         
                           
                             v 
                             2 
                           
                           - 
                           
                             v 
                             b 
                             2 
                           
                         
                         ) 
                       
                       
                         2 
                         ⁢ 
                         β 
                       
                     
                     - 
                     
                       vT 
                       d 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     In this Equation (1), a speed limit position x atp (v) with respect to a speed v when a stop position or a speed limit start position x b  and a deceleration completion speed v b  are given, is expressed. 
     The vehicle speed limit unit  100  sets the speed limit curve according to the speed limit start position acquired from the ground ATP device  200  and Equation (1). 
       FIG. 3  is a diagram showing an example of the travel curve generated by the travel control device  3  according to the first embodiment. 
     The limit information acquisition unit  101  included in the travel control device  3  inputs the limit information including a sequence of the relative positions in which the position having a margin of maximum position error with respect to the current position recognized by the vehicle speed limit unit  100  is set as the current position, from the vehicle speed limit unit  100 . The limit information acquisition unit  101  outputs the input limit information to the travel curve generation unit  104 . 
     The travel curve generation unit  104  generates a travel curve that satisfies the speed limit at each position obtained from the limit information according to the limit information acquired from the limit information acquisition unit  101 , the current position acquired from the current position acquisition unit  102 , and the current speed acquired from the current speed acquisition unit  103 . 
     The vehicle speed limit unit  100  which is an on-vehicle ATP device and the current position acquisition unit  102  included in the ATO device recognize the current position according to the speed limit start position acquired from the same ground ATP device  200 . Therefore, the travel curve generation unit  104  may have only the recognition position error caused by a transmission time difference between a signal transmission time from the ground ATP device  200  to the vehicle speed limit unit  100  and a signal transmission time from the ground ATP device  200  to the current position acquisition unit  102  with respect to the current position acquired from the current position acquisition unit  102 , as the margin. As a result thereof, the travel curve generation unit  104  has a sum of the recognition position error of the ATP device and the maximum value of the recognition position error caused by the transmission time difference as the margin. Usually, since the recognition position error caused by the transmission time difference is small enough to be almost negligible compared to the recognition position error of the ATP device, the travel curve generation unit  104  can reduce the margin of the recognition position error of the ATO device. The travel curve generation unit  104  inputs the limit information including the sequence of the relative positions with respect to the current position from the limit information acquisition unit  101 . In a case where the accuracy of each relative position included in the limit information input from the limit information acquisition unit  101  by the travel curve generation unit  104  is desired to be improved, the travel curve generation unit  104  generates the speed limit curve by performing, for example, a linear interpolation on the values between each sequence. Then, the travel curve generation unit  104  generates a curve having the margin of, for example, five km per hour with respect to the speed limit curve as a target travel curve. 
       FIG. 4  is a diagram showing an example of a processing flow of the traffic system  1  including the travel control device  3  according to the first embodiment of the present invention. 
     Next, the processing by the traffic system  1  including the travel control device  3  according to the first embodiment will be described. 
     It is assumed that the vehicle  2  included in the traffic system  1  according to the first embodiment travels on a road surface on which a travel condition such as the guaranteed deceleration β in Equation (1) changes for each installation position of the ground ATP device  200 . In addition, it is assumed that the vehicle speed limit unit  100  acquires the speed limit start position, the limit information, and the current position of the vehicle  2  from the ground ATP device  200  for each change of the travel condition. In addition, at this time, it is assumed that the current position acquisition unit  102  acquires the speed limit start position from the ground ATP device  200 . 
     In the traffic system  1 , during the travelling of the vehicle  2 , the vehicle speed limit unit  100  included in the vehicle  2  performs a wireless communication with the ground ATP device  200 . Then, the vehicle speed limit unit  100  acquires the speed limit start position, the limit information, the current position of the vehicle  2 , and the current speed of the vehicle  2  from the ground ATP device  200  (STEP  51 ). 
     The vehicle speed limit unit  100  sets the speed limit at each position according to the speed limit start position acquired from the ground ATP device  200  and Equation (1) in order to achieve a predetermined deceleration completion speed at the speed limit start position, that is, the speed limit curve (STEP S 2 ). 
     The vehicle speed limit unit  100  outputs the state of the speed limit curve acquired according to the speed limit start position and Equation (1) to the limit information acquisition unit  101  included in the travel control device  3  as the limit information including the sequence of the relative positions from the current position (STEP S 3 ). 
     When the limit information including the sequence of the relative positions from the current position is input from the vehicle speed limit unit  100 , the limit information acquisition unit  101  outputs the input limit information to the travel curve generation unit  104 . 
     In addition, the current speed acquisition unit  103  acquires the current speed of the vehicle  2  from the speedometer included in the vehicle  2  (STEP S 4 ). The current speed acquisition unit  103  outputs the acquired current speed to the current position acquisition unit  102  and the travel curve generation unit  104 . 
     When the current speed is input from the current speed acquisition unit  103 , the current position acquisition unit  102  calculates the current position according to the accumulation value of the speed limit start position acquired from the ground ATP device  200  and the input current speed (STEP S 5 ). The current position acquisition unit  102  outputs the calculated current position to the travel curve generation unit  104 . 
     The travel curve generation unit  104  inputs the limit information from the limit information acquisition unit  101 . The travel curve generation unit  104  inputs the current speed from the current speed acquisition unit  103 . In addition, the travel curve generation unit  104  inputs the current position from the current position acquisition unit  102 . Then, the travel curve is generated, which satisfies the speed limit at each position obtained from the limit information according to the input limit information, the current position, and the current speed (STEP S 6 ). For example, as shown in  FIG. 3 , the travel curve generation unit  104  obtains the current position which is the recognition position by the travel control device  3  according to the current position and the current speed, and obtains the speed limit curve using the current position and the sequence of the relative positions from the current position included in the limit information. Then, the travel curve generation unit  104  generates the target travel curve having the margin of speed limit error with respect to the obtained speed limit curve. The travel curve generation unit  104  generates a curve having the margin of, for example, five km per hour as the target travel curve. 
     The travel curve generation unit  104  outputs the generated travel curve to the speed command unit  105 . 
     The speed command unit  105  generates the speed command according to the input travel curve and the current position (STEP S 7 ). The speed command unit  105  outputs the speed command to the control unit that controls the speed of the vehicle  2  (STEP S 8 ). 
     As described above, the processing flow of the traffic system  1  including the travel control device  3  according to the first embodiment of the present invention is described. By the travel control device  3  included in the traffic system  1  described above, the speed limit at each position in order to achieve a predetermined deceleration completion speed at the speed limit start position is set according to the speed limit start position acquired from the ground ATP device  200 . The travel control device  3  acquires the limit information including the speed limit information the position information corresponding to the speed limit. The travel control device  3  acquires the current position of the vehicle  2 , acquires the current speed of the vehicle  2 , and generates the travel curve that satisfies the speed limit at each position obtained from the limit information according to the acquired limit information, the current position, and the current speed. The travel control device  3  generates the speed command according to the generated travel curve and the current position. 
     In this way, when the vehicle  2  performs the automatic driving using the travel control device  3 , it is possible to reduce the travelling time of the train with respect to the travelling distance. 
     Next, a second embodiment will be described. 
       FIG. 5  is a diagram showing an example of a processing flow of the traffic system  1  including a travel control device  3  according to the second embodiment of the present invention. 
     In addition,  FIG. 6  is a diagram showing an example of a travel curve generated by the travel control device  3  according to the second embodiment of the present invention. 
     Next, the processing by the traffic system  1  including the travel control device  3  according to the second embodiment will be described using  FIG. 5  and  FIG. 6 . 
     It is assumed that the vehicle  2  included in the traffic system  1  according to the second embodiment travels on a road surface on which a gradient or the like changes and a travel condition such as the guaranteed deceleration β expressed in Equation (1) changes. In addition, it is assumed that the travel control device  3  holds Equations (2) to Equation (4) described below. 
     In addition, here, only processing steps different from that in the first embodiment will be described in detail. 
     After generating the sequence of the relative positions from the current position by performing the processing items in STEP  51  and STEP S 2 , similarly to the first embodiment, the vehicle speed limit unit  100  according to the second embodiment outputs limit information including only the sequences corresponding to the representative two speeds among the sequences of the relative positions from the current position to the travel control device  3  (STEP S 9 ). For example, the limit information including a speed v 1  in which below the decimal point of the current speed is rounded down, a relative distance x 1  from the current position at the speed v 1 , a speed v 2  which is lower than v 1  by one km per hour, and a relative distance x 2  from the current position at the speed v 2 , are output to the travel control device  3 . Then, the processing items in STEP S 4  and STEP S 5  are performed. 
     The limit information acquisition unit  101  included in the travel control device  3  inputs the limit information including only the sequences corresponding the representative two speeds among the sequence of the relative positions from the current position from the vehicle speed limit unit  100 . The limit information acquisition unit  101  outputs the limit information input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The current position acquisition unit  102  inputs the current position from the vehicle speed limit unit  100 . The current position acquisition unit  102  outputs the current position input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The current speed acquisition unit  103  inputs the current speed from the vehicle speed limit unit  100 . The current speed acquisition unit  103  outputs the current speed input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The travel curve generation unit  104  inputs the limit information, the current position, and the current speed from the limit information acquisition unit  101 , the current position acquisition unit  102 , and the current speed acquisition unit  103  respectively. Then, the travel curve generation unit  104  calculates the guaranteed deceleration β and the relative position d b  of the deceleration completion position by substituting the input limit information into the holding Equation (2) below. 
     
       
         
           
             
               
                 
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     Next, the travel curve generation unit  104  substitutes the current position input from the vehicle speed limit unit  100 , the current speed, the calculated guaranteed deceleration β, and the relative position d b  into the holding Equation (3) below. Then, the travel curve generation unit  104  generates the speed limit curve shown in  FIG. 6  (STEP S 10 ). 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
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                     ( 
                     3 
                     ) 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     
                       x 
                       atp 
                       ′ 
                     
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                       ( 
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                         2 
                       
                       
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     Then, the travel curve generation unit  104  generates Equation (4) below having the margin of, for example, five km per hour as the travel curve with respect to the speed limit curve generated according to Equation (3) (STEP S 11 ). Then, the processing items in STEP S 7  and STEP S 8  are performed.
 
Equation (4)
 
 x   atp ( v )= x′   atp ( v+ 2)  (4)
 
     As described above, the processing flow of the traffic system  1  including the travel control device  3  according to the second embodiment of the present invention is described. By the travel control device  3  included in the traffic system  1  described above, the speed limit at each position in order to achieve a predetermined deceleration completion speed at the speed limit start position is set according to the speed limit start position acquired from the ground ATP device  200 . The travel control device  3  acquires the limit information including the two representative speed limit information items and the position information corresponding to the speed limit. The travel control device  3  acquires the current position of the vehicle  2 , acquires the current speed of the vehicle  2 , and generates the travel curve according to the acquired limit information, the current position, and the current speed. The travel control device  3  generates the speed command according to the generated travel curve and the current position. 
     In this way, when the vehicle  2  performs the automatic driving using the travel control device  3 , it is possible to reduce the travelling time of the train with respect to the travelling distance. 
     In addition, an amount of information output from the vehicle speed limit unit  100  to the travel control device  3  is reduced, and thus, an amount of communication performed by the travel control device  3  is reduced and a transmission delay is reduced. As a result thereof, it is possible to reduce the manufacturing cost of the travel control device  3 . 
     Next, a third embodiment will be described. 
       FIG. 7  is a diagram showing an example of a processing flow of the traffic system  1  including a travel control device  3  according to the third embodiment of the present invention. 
     Next, the traffic system  1  including the travel control device  3  according to the third embodiment of the present invention will be described. 
     It is assumed that the vehicle speed limit unit  100  according to the third embodiment sets the speed limit curve according to the speed limit start position acquired from the ground ATP device  200  and Equation (1) in which the guaranteed deceleration β are regarded to be constant. In addition, it is assumed that the travel control device  3  holds Equation (5) expressed below. 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
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                     5 
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     The processing items in STEP  51  and STEP S 2  are performed. Then, the vehicle speed limit unit  100  outputs the limit information including a relative position db up to the deceleration completion position at which the speed shown in  FIG. 6  becomes zero, a speed vb, and the guaranteed deceleration β, to the travel control device  3  (STEP S 12 ). 
     The limit information acquisition unit  101  included in the travel control device  3  inputs the limit information including the relative position db up to the deceleration completion position, the speed vb, and the guaranteed deceleration β from the vehicle speed limit unit  100 . The limit information acquisition unit  101  outputs the limit information input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The current position acquisition unit  102  inputs the current position from the vehicle speed limit unit  100 . The current position acquisition unit  102  outputs the current position input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The current speed acquisition unit  103  inputs the current speed from the vehicle speed limit unit  100 . The current speed acquisition unit  103  outputs the current speed input from the vehicle speed limit unit  100  to the travel curve generation unit  104 . 
     The travel curve generation unit  104  inputs the limit information, the current position, and the current speed from the limit information acquisition unit  101 , the current position acquisition unit  102 , and the current speed acquisition unit  103  respectively. Then, the travel curve generation unit  104  substitutes the input limit information, the current position, and the current speed into Equation (5) held in the travel control device  3 , and generates the speed limit curve (STEP S 13 ). Then, the processing items in STEP S 11 , STEP S 7 , and STEP S 8  are performed. 
     In this way, when the vehicle  2  performs the automatic driving using the travel control device  3 , it is possible to reduce the travelling time of the train with respect to the travelling distance. 
     In addition, an amount of information output from the vehicle speed limit unit  100  to the travel control device  3  is reduced, and thus, an amount of communication performed by the travel control device  3  is reduced. As a result thereof, it is possible to reduce the manufacturing cost of the travel control device  3 . 
     When the travel curve generation unit  104  in the second embodiment or in the third embodiment generates the travel curve from the speed limit curve, the travel curve may be generated such that the speed margin increases as the speed of the vehicle  2  increases. 
     For example, the travel curve generation unit  104  may add a term “−0.2v” that corrects the transmission delay or a term “−0.01v 2 ” that corrects a bad effect of the regenerative brake such as “x ato (v)=x′ ato (v−2)−0.2v−0.01v 2 ”. 
     In this way, it is possible to reduce a risk that the brake operates while being closer to the speed limit curve as the travel speed of the vehicle  2  is in the high speed range. 
     In addition, the control described with respect to the traffic system  1  including the travel control device  3  according to the embodiments of the present invention is not limited to a control of the position up to the deceleration completion request position shown in  FIG. 2 . The control described with respect to the traffic system  1  including the travel control device  3  according to the embodiments of the present invention can be similarly applied to a deceleration control up to a stop limit (speed limit of the speed 0) of the vehicle  2 . 
     The embodiments of the present invention are described. However, a computer system is included in the travel control device  3 , the vehicle speed limit unit  100 , and the ground ATP device  200 . Then, the processing procedures described above are stored in a computer readable recording medium as a form of a program, and the processing items described above are executed by the computer reading and executing the program. Here, the examples of the computer readable recording medium include a magnetic disk, an optical magnetic disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. In addition, the computer program may be distributed to computers via a communication line and the computer receiving the distribution may execute the program. 
     In addition, the program described above may be a program for realizing a part of the functions described above. Furthermore, the program described above may be a program that can realize the functions described above by a combination with a program already recorded in a computer system, so-call a differential file (a differential program). 
     Some of the embodiments of the present invention are described. However, the described embodiments are just provided as examples and do not limit the scope of the invention. In addition, various omissions, substitutions, and modifications can be made without departing from the scope of the invention. 
     INDUSTRIAL APPLICABILITY 
     According to the travel control device, the vehicle, the traffic system, the control method, and the program described above, when the automatic driving is performed on the vehicle, it is possible to reduce the travelling time of the train with respect to the travelling distance. 
     REFERENCE SIGNS LIST 
     
         
           1  traffic system 
           2  vehicle 
           3  travel control device 
           100  vehicle speed limit unit 
           101  limit information acquisition unit 
           102  current position acquisition unit 
           103  current speed acquisition unit 
           104  travel curve generation unit 
           105  speed command unit 
           200  ground ATP device