Patent Publication Number: US-2021182576-A1

Title: Recognition Device

Description:
TECHNICAL FIELD 
     The present invention relates to a recognition device that recognizes a position at which a vehicle is to be stopped. 
     BACKGROUND ART 
     Development of autonomous driving technology is actively under way all over the world, and levels  1  to  5  defined by SAE (Society of Automotive Engineers) are often used as levels of automation. According to the definition of SAE, a system is responsible for vehicle control at level  3  or higher. Therefore, in order to realize level  3  or higher autonomous driving, not only vehicle control such as traveling according to a lane, but also vehicle control according to traffic regulations need to be performed on system responsibility. 
     One of the traffic regulations is to stop a vehicle just in front of a stop line. Therefore, a vehicle having a level  3  or higher autonomous driving function must have a function of obtaining relative position information between the stop line and the vehicle by some means. 
     PTL 1 discloses a technique for shifting to a stop line recognition mode based on a color of a traffic light. According to the technique of PTL 1, an image processing unit  4  recognizes a traffic light ahead on a host vehicle traveling lane and, in a case where the image processing unit  4  recognizes that the traffic light just in front of the host vehicle on the host vehicle traveling lane is located within a preset distance L 2  and the color of the traffic light is red, shifts to the stop line recognition mode and executes stop line recognition processing. According to PTL 1, this can properly save unnecessary execution of the stop line recognition processing, thereby accurately recognizing a stop line necessary for control of the host vehicle  1  without causing an excessive computation load. 
     PTL 2 discloses a technique of a fixed point stop control method for a vehicle. According to the technique of PTL 2, a rear camera  101  or a front camera  102  is used to recognize markers on a road surface in all directions. Examples of the markers are a pedestrian crossing, a temporary stop line, and a pedestrian crossing notice. A kind of target recognized by the rear camera  101  or the front camera  102  and a distance to the target are calculated and sent to a locator unit  11 . The locator unit  11  pinpoints the position where the vehicle is currently traveling. According to PTL 2, deceleration control is realized based on information generated by the locator unit  11  on the position where the host vehicle is currently traveling. 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2011-123613 A 
     PTL 2: JP 2009-196487 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, according to the technique for shifting to the stop line recognition mode described in PTL 1, there is a problem that the shift to the stop line recognition mode does not occur in a place where there is no traffic light. Positional accuracy of the locator information of PTL 2 may undesirably decrease since a traveling distance from a time of recognition of a target such as a marker sometimes becomes long. 
     The inventors newly found that stop line detection using a camera has the following problems. 
     (1) A road surface structure, such as an asphalt seam, that extends laterally with respect to a host vehicle driving lane is erroneously detected as a stop line. 
     (2) A faded stop line cannot be detected. 
     Furthermore, the inventors found that it is necessary to generate information for stopping a vehicle at a predetermined position even in a case where a stop line cannot be detected. 
     The present invention has been made in view of the above problems, and an object of the present invention is to provide a recognition device that can accurately recognize a position where a vehicle is to be stopped. 
     Solution to Problem 
     A typical example of the present invention is summarized as follows. 
     A recognition device according to the present disclosure includes: a first sensor that detects a first feature; and at least one information source different from the first sensor, in which an operation start time of the first sensor is determined based on operation start information output from the first sensor or the information source. 
     Advantageous Effects of Invention 
     An example obtained by the typical example of the present invention is briefly described as follows. According to the present invention, a position where a vehicle is to be stopped can be accurately recognized. 
     Additional features related to the present invention will become apparent from the specification and drawings. Furthermore, problems, configurations, and effects other than those described above will become apparent from the descriptions of embodiments below. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 2  is a signal processing flowchart of the stop line detection system and the autonomous driving method using the stop line detection system. 
         FIG. 3  illustrates a technical outline of the stop line detection system. 
         FIG. 4  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 5  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 6  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 7  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 8  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 9  is a functional block diagram of a stop line detection system and an autonomous driving method using the stop line detection system. 
         FIG. 10  illustrates a technical outline of the stop line detection system. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Best modes for carrying out the present invention will be described in detail below with reference to the drawings. In all of the drawings for explaining the embodiments for carrying out the invention, blocks or elements having identical functions are given identical reference signs, and repeated description thereof is omitted. 
     The embodiments below describe, as an example, a stop line detection system for detecting a position at which a vehicle is to be stopped by using an outside information detection sensor and controlling the vehicle to stop on system judgment and an autonomous driving system using the stop line detection system. 
     First Embodiment 
       FIG. 1  is a functional block diagram of a stop line detection system according to the first embodiment and an autonomous driving method using the stop line detection system, and  FIG. 2  is a flowchart of signal processing of the stop line detection system according to the first embodiment and the autonomous driving method using the stop line detection system.  FIG. 3  illustrates a technical outline of the stop line detection system according to the first embodiment. 
     The stop line detection system has a sensor  10   a , which is a first sensor, an information source  20   a , which is a first information source, a fusion unit  30   a , which is a first fusion unit, and a planning/judgment unit  40 . 
     The sensor  10   a  is a sensor that detects a feature in front of a host vehicle and is attached to the host vehicle. The sensor  10   a  has a stop line detection processing unit  130   a  that detects a stop line  2  as a first feature. The stop line  2  is drawn on a road surface, and a rule requires vehicles to stop just in front of the stop line  2 . The sensor  10   a  is preferably a camera (visible light, near infrared, far infrared) or LiDAR (Laser Imaging and Ranging), but is not limited to these, and may be, for example, a sensor of other kinds that can detect a stop line drawn on a road surface or a stop line formed as a three-dimensional structure on a road surface. 
     The information source  20   a  has, as one or more information sources different from the sensor  10   a , a map information acquisition unit  100  that acquires map information, a locator  110  that acquires a position of the host vehicle, and a host vehicle information acquisition unit  120  that acquires information such as a direction in which the host vehicle is traveling and a vehicle speed. 
     The fusion unit  30   a  determines an operation start time of the sensor  10   a  based on operation start information output from the sensor  10   a  or the information source  20   a , and has a map information processing calculation unit  200   a  that acquires and processes map information from the information source  20   a  and a map information-sensing result unifying unit  300   a  that unifies a calculation result of the map information processing calculation unit  200   a  and a processing result of the stop line detection processing unit  130   a  of the sensor  10   a . The map information processing calculation unit  200   a  has a distance calculation unit  210  for calculating a distance to a stop line that calculates a road distance between the host vehicle and a stop line. The map information-sensing result unifying unit  300   a  has a stop line position unifying unit  310  that unifies map information and a sensing result and a distance estimation unit  320  for estimating a distance to a stop line that estimates a distance to a stop line. 
     The planning/judgment unit  40  has a track planning unit  400  and a speed planning unit  410 . The track planning unit  400  calculates a track on which the host vehicle travels based on information on a distance to a stop line supplied from the fusion unit  30   a , and the speed planning unit  410  calculates a speed for stopping the host vehicle at the stop line  2 . 
     In  FIG. 1, 800   a  is data sent from the map information acquisition unit  100 ,  800   b  is data sent from the locator  110 , and  800   c  is data sent from the host vehicle information acquisition unit  120 . In  FIGS. 1, 810   a  and  810   b  are data sent from the distance calculation unit  210  for calculating a distance to the stop line to the sensor  10   a  and the stop line position unifying unit  310 . 
     In  FIG. 1, 820   a  is data sent from the sensor  10   a  to the map information-sensing result unifying unit  300   a ,  830   a  is data sent from the map information-sensing result unifying unit  300   a  to the planning/judgment unit  40  and the distance estimation unit  320  for estimating a distance to a stop line, and  830   b  is data sent from the distance estimation unit  320  for estimating a distance to a stop line to the stop line position unifying unit  310 . 
     In  FIGS. 2, 900   a  to  900   j  are signal processing steps, and  910  is a determination processing step. 
       FIG. 3  illustrates a left white line  1   a  of a host vehicle driving lane, a right white line  1   b  of the host vehicle driving lane, a stop line  2 , a stop line detection area  3 , and an error  4   a  of a road distance to a map-based stop line based on the map information. 
     Operation of the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIGS. 1 to 3 . 
     The data  800   a  sent from the map information acquisition unit  100  includes latitude and longitude information of stop lines registered in the map information and travel route information ahead and behind the host vehicle, the data  800   b  sent from the locator  110  includes latitude and longitude location of the host vehicle, orientation information, and latitude and longitude error information, and the data  800   c  sent from the host vehicle information acquisition unit  120  includes information such as a speed, a roll angle, a pitch angle, a yaw angle, and a steering angle of the host vehicle. 
     The distance calculation unit  210  for calculating a distance to the stop line calculates a road distance (map information distance) to the map-based stop line  2  and an error (error distance)  4   a  of the road distance to the map-based stop line  2  based on at least one of the data  800   a ,  800   b , and  800   c  (signal processing step  900   a ). The distance calculation unit  210  for calculating a distance to the sop line corresponds to a distance calculation unit that calculates a map information distance between a host vehicle and a target feature based on map information in claim  9 . 
     In a case where the road distance to the map-based stop line  2  is equal to or less than a predetermined determination value (YES in the determination processing step  910 ), the distance calculation unit  210  for calculating a distance to the stop line sends, as the data  810   a , the road distance to the map-based stop line  2  and the error  4   a  of the road distance to the map-based stop line  2  to the sensor  10   a  and the map information-sensing result unifying unit  300   a  (signal processing steps  900   b  and  900   c ). Furthermore, in a case where the road distance to the map-based stop line  2  is equal to or less than the predetermined determination value, the distance calculation unit  210  for calculating a distance to the stop line sends, as the data  810   b , a processing operation start flag to the sensor  10   a  and the map information-sensing result unifying unit  300   a  (signal processing steps  900   b  and  900   c ). 
     The sensor  10   a  starts operation of the stop line detection processing unit  130   a  in accordance with the data  810   b  including the processing operation start flag. A time at which the operation of the stop line detection processing unit  130   a  starts is set as a time T 0  (operation start time). The stop line detection processing unit  130   a  of the sensor  10   a  limits a range of processing for detecting the stop line  2  based on positional information of the stop line  2  output from the sensor  10   a  or the information source  20   a . The stop line detection processing unit  130   a  sets, as the stop line detection area  3 , an area obtained by adding the error  4   a  of the road distance to the map-based stop line  2  to front and rear sides of the road distance to the map-based stop line  2  obtained from the data  810   a  (signal processing step  900   d ). 
     The error  4   a  varies depending on the accuracy of the data  800   a ,  800   b , and  800   c . Therefore, the stop line detection area  3  set in accordance with the error  4   a  is enlarged or reduced depending on the accuracy. The sensor  10   a  changes an area where the stop line  2  is detected based on information on accuracy of the positional information of the stop line  2  output from the sensor  10   a  or the information source  20   a.    
     In  FIG. 3 , a length of the stop line detection area  3  in a lateral direction (road width direction) may be determined by any method. For example, in a case where the map information includes information on a host vehicle driving lane width, the length of the stop line detection area  3  in the lateral direction may be calculated according to the lane width included in the map information. 
     Alternatively, for example, in a case where the sensor  10   a  or a sensor other than the sensor  10   a  provided in the host vehicle has a function of detecting the host vehicle driving lane width (a function of detecting an interval between the left white line  1   a  and the right white line  1   b  of the host vehicle driving lane in  FIG. 3 ), the length of the stop line detection area  3  in the lateral direction may be calculated in accordance with a sensing result of the lane width. 
     The stop line detection processing unit  130   a  detects the stop line  2  through sensing within the stop line detection area  3  and calculates a road distance between the host vehicle and the stop line  2  (signal processing step  900   e ). Then, the stop line detection processing unit  130   a  sends, as the data  820   a , the distance (actually-measured distance) to the stop line, which is a detection result, to the stop line position unifying unit  310  (signal processing step  900   f ). The processes in the signal processing steps  910  to  900   f  corresponds to a target feature detection processing unit that, in a case where the map information distance is equal to or less than a determination value, sets a detection area for detection of the target feature based on the map information distance, detects the target feature within the detection area, and calculates an actually-measured distance between the host vehicle and the target feature in claim  9 . 
     The stop line position unifying unit  310  starts the following operation at a time T 0  in accordance with the data  810   b  including the processing operation start flag. The stop line position unifying unit  310  unifies the data  820   a  including the sensing result of the road distance to the stop line  2  and the data  810   a  including the road distance to the map-based stop line  2  and sends, as the data  830   a , a calculated unification result of the road distance to the stop line (signal processing step  900   g ). The stop line position unifying unit  310  corresponds to a unification result calculation unit that unifies data of the map information distance and data of the actually-measured distance to calculate a unification result of a distance between the host vehicle and the target feature in claim  9 . 
     To unify the two data  820   a  and  810   a  in the signal processing step  900   g , it is desirable to use an αβ filter, a Kalman filter, or the like, but other methods may be used. 
     The data  830   a  is input to the road distance estimation unit  320  (signal processing step  900   h ) for estimating a road distance to the stop line, and the road distance estimation unit  320  for estimating a road distance to the stop line calculates an estimation result of a road distance to the stop line at a time T 0 +ΔT. That is, the road distance estimation unit  320  estimates a road distance to the stop line at the time (T 0 +ΔT), which is a time after elapse of a predetermined time from the time T 0 , based on the data  830   a  of the unification result of the road distance to the stop line  2 . The road distance estimation unit  320  for estimating a road distance to the stop line corresponds to a distance estimation unit that estimates a distance between a position of the host vehicle and the target feature after elapse of a predetermined time from a time of start of operation for detecting the target feature by the target feature detection processing unit in claim  10 . 
     The estimation result of the road distance to the stop line is sent to the stop line position unifying unit  310  as the data  830   b  (signal processing step  900   j ). At or after the time T 0 +ΔT, the stop line position unifying unit  310  unifies the data  820   a ,  810   a , and  830   b  to calculate a unification result of the road distance to the stop line and sends the unification result as the data  830   a . The time T 0 +ΔT is a time after elapse of a predetermined time ΔT from the time T 0  at which the stop line detection processing unit  130   a  starts the operation for detecting the stop line  2 , and ΔT is a signal processing cycle time of the fusion unit  30   a . That is, the stop line position unifying unit  310  initially calculates a unification result of the road distance to the stop line by unifying the data  820   a  and  810   a  and thereafter calculates a unification result of the road distance to the stop line by unifying the data  820   a ,  810   a , and  830   b  every signal processing cycle time ΔT of the fusion unit  30   a.    
     The data  830   a  is sent to the planning/judgment unit  40  (signal processing step  900   i ). Based on the input unification result of the road distance to the stop line, the planning/judgment unit  40  causes the track planning unit  400  to calculate a track plan along which the host vehicle should travel and causes the speed planning unit  410  to calculate a speed plan. 
     Through the above operation, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the stop line detection area  3  can be limited in the stop line detection processing unit  130   a  of the sensor  10   a . This can increase a stop line detection rate. Further, since the stop line detection processing unit  130   a  and the stop line position unifying unit  310  operate only in a case where the distance between the host vehicle and the stop line is equal to or less than the predetermined determination value, power consumption can be reduced as compared with a case where the stop line detection processing unit  130   a  and the stop line position unifying unit  310  always operate. 
     In the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the sensor  10   a  is preferably a camera (visible light, near infrared, far infrared) or LiDAR (Laser Imaging and Ranging), but the effects of the present invention can be obtained even in a case where the sensor  10   a  is a sensor of other kinds that can detect a feature such as a stop line drawn on a road surface or a stop line formed as a three-dimensional structure on a road surface. 
     Further, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the stop line detection processing unit  130   a  is provided in the sensor  10   a , but the stop line detection processing unit  130   a  may be provided in the fusion unit  30   a . In this case, in a case where the sensor  10   a  is a camera, for example, image data is transmitted from the sensor  10   a  to the stop line detection processing unit  130   a  provided in the fusion unit  30   a.    
     A proper degree of pre-processing of the image data may be selected according to a signal processing capacity of the sensor  10   a , a signal processing capacity of the fusion unit  30   a , and a capacity of a communication unit connecting the sensor  10   a  and the fusion unit  30   a.    
     Furthermore, for example, error information of the latitude and longitude of location of the host vehicle according to a satellite positioning reception status in the locator  110  is desirably used as a standard for calculation of the error  4   a , but the error  4   a  may be calculated by other means. It is desirable that the error  4   a  be time-variable according to the error information of the latitude and longitude of location of the host vehicle, but the error  4   a  may be a fixed value. 
     According to the recognition device according to the present embodiment, the data  800   a ,  800   b , and  800   c  are sent from the information source  20   a  to the map information processing calculation unit  200   a  of the fusion unit  30   a . The map information processing calculation unit  200   a  of the fusion unit  30   a  processes the map information based on the data  800   a ,  800   b , and  800   c , and causes the distance calculation unit  210  for calculating a distance to the stop line to calculate a road distance (map information distance) to the map-based stop line  2  and the error (error distance)  4   a  of the road distance to the map-based stop line  2 . In a case where the road distance to the map-based stop line  2  is equal to or less than a predetermined determination value, the map information processing calculation unit  200   a  sends, as the data  810   a , the road distance to the map-based stop line and the error  4   a  of the road distance to the map-based stop line to the sensor  10   a . Furthermore, in a case where the distance to the map-based stop line is equal to or less than the predetermined determination value, the map information processing calculation unit  200   a  sends the data  810   b  of the processing operation start flag to the sensor  10   a.    
     The sensor  10   a  starts the operation of the stop line detection processing unit  130   a  in accordance with the processing operation start flag, performs sensing within the detection area, detects the stop line, and calculates a road distance from the host vehicle to the stop line. The stop line detection processing unit  130   a  sets, as the stop line detection area  3 , an area obtained by adding the error  4   a  of the road distance to the map-based stop line to front and rear sides of the road distance to the map-based stop line, and performs sensing within the stop line detection area. Then, the stop line detection processing unit  130   a  calculates a measured distance between the host vehicle and the stop line detected by the sensing and sends, as the data  820   a , the measured distance to the map information-sensing result unifying unit  300   a  of the fusion unit  30   a.    
     In the map information-sensing result unifying unit  300   a , the stop line position unifying unit  310  calculates a unification result by unifying data of the road distance to the map-based stop line and data of the road distance to the stop line actually measured by the sensing. The data  830   a  of the unification result is input to the distance estimation unit  320  for estimating a distance to the stop line, and the distance estimation unit  320  for estimating a distance to the stop line estimates a distance to the stop line after elapse of a signal processing cycle time ΔT from the operation start time T 0  of the stop line detection processing unit  130   a . The distance estimated by the distance estimation unit  320  for estimating a distance to the stop line is sent to the stop line position unifying unit  310  as the data  830   b . The stop line position unifying unit  310  unifies the data  810   a ,  820   a , and  830   b , and sends data of the distance to the stop line, which is a unification result, to the planning/judgment unit  40 . 
     According to the recognition device according to the present embodiment, a unification result of a distance between a host vehicle and a stop line is calculated by unifying data of a road distance to a map-based stop line and data of a road distance to the stop line actually measured by sensing, and the unification result is sent to the planning/judgment unit  40 , and therefore even if any one of the data of the road distance to the map-based stop line and the data of the road distance to the stop line actually measured by sensing is unavailable, data can be sent to the planning/judgment unit  40 , and the host vehicle can be stopped at a position of the stop line. Since the stop line detection area  3  can be limited in the stop line detection processing unit  130   a  of the sensor  10   a , a detection rate of the stop line  2  by the sensor  10   a  can be increased. Further, since the stop line detection processing unit  130   a  operates only in a case where the distance between the host vehicle and the stop line is equal to or less than a predetermined determination value, power consumption can be reduced as compared with a case where the stop line detection processing unit  130   a  always operates. 
     Second Embodiment 
       FIG. 4  is a functional block diagram of a stop line detection system according to the second embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the second embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 4 . Constituent elements similar to those in the first embodiment are given identical reference signs, and detailed description thereof is omitted. 
     A feature of the present embodiment lies in that a map information processing calculation unit  200   b  has a host vehicle position estimation error calculation unit  220  and is thus configured to narrow a stop line detection area by reducing an error distance of a road distance to a map-based stop line as the host vehicle approaches the stop line and the road distance becomes shorter. 
     In  FIG. 4, 30   b  is a second fusion unit, and  200   b  is a map information processing calculation unit. In  FIG. 4, 220  is a host vehicle position estimation error calculation unit, which is included in the map information processing calculation unit  200   b . In  FIG. 4, 810   c  is data sent from the host vehicle position estimation error calculation unit  220 , and  830   c  is data sent from a stop line position unifying unit  310 . 
     The host vehicle position estimation error calculation unit  220  calculates an error  4   b  of a road distance to a map-based stop line at a time T 0  based on error information of latitude and longitude of location of the host vehicle included in data  800   b  sent from a locator  110  and sends, as the data  810   c , the error  4   b  to a stop line detection processing unit  130   a  of a sensor  10   a.    
     The stop line detection processing unit  130   a  provided in the sensor  10   a  limits a stop line detection area  3  by using the error  4   b  of the road distance to the map-based stop line in the data  810   c.    
     The stop line position unifying unit  310  performs operation similar to that in the first embodiment and calculates a unification error obtained in unification of the two data  820   a  and  810   a  and sends the unification error as the data  830   c  at a time T 0 +ΔT. For example, in a case where a Kalman filter is used, a size of an error ellipse can be used as the unification error. 
     The data  830   c  is sent to the host vehicle position estimation error calculation unit  220 , is unified with error information of the latitude and longitude of location of the host vehicle at the time T 0 +ΔT by the host vehicle position estimation error calculation unit  220 , is calculated as the error  4   b  of the road distance to the map-based stop line at the time T 0 +ΔT, and is further sent as the data  810   c  to the stop line detection processing unit  130   a  provided in the sensor  10   a.    
     Through the above operation, in the stop line detection system according to the second embodiment and the autonomous driving method using the stop line detection system, the error  4   b  of the road distance to the map-based stop line becomes smaller with passage of time, and the stop line detection area  3  becomes smaller accordingly. This can increase a stop line detection rate as compared with the first embodiment. 
     Third Embodiment 
       FIG. 5  is a functional block diagram of a stop line detection system according to the third embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the third embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 5 . Constituent elements similar to those in the first embodiment are given identical reference signs, and detailed description thereof is omitted. 
     In  FIG. 5, 10   b  is a second sensor,  30   c  is a third fusion unit,  200   c  is a map information processing calculation unit, and  300   b  is a map information-sensing result unifying unit. In  FIG. 5, 140  is a white line detection processing unit, which is included in the second sensor  10   b . The map information processing calculation unit  200   c  has a distance calculation unit  210  for calculating a distance to a stop line, a host vehicle position estimation error calculation unit  220 , and a white line position calculation unit  230 . 
     In  FIG. 5, 330  is a white line position unifying unit,  340  is a white line position estimation unit, the white line position unifying unit  330  and the white line position estimation unit  340  are included in the map information-sensing result unifying unit  300   b . In  FIG. 5, 800   a ′ is data sent from a map information acquisition unit  100 ,  810   d  is data sent from the white line position calculation unit  230 ,  820   b  is data sent from the white line detection processing unit  140 ,  830   d  and  830   e  are data sent from the white line position unifying unit  330 , and  830   f  is data sent from the white line position estimation unit  340 . 
     In the stop line detection system according to the third embodiment and the autonomous driving method using the stop line detection system, the data  800   a ′ has at least latitude and longitude information, curvature information, and gradient information of a left white line  1   a  and a right white line  1   b  of a host vehicle traveling lane in addition to the information described in the first embodiment and the second embodiment. 
     Based on the data  800   a ′,  800   b , and  800   c , the white line position calculation unit  230  calculates at least map-based positions of the left white line  1   a  and the right white line  1   b  of the host vehicle traveling lane from a host vehicle and send the positions as the data  810   d.    
     The white line detection processing unit  140  provided in the sensor  10   b  detects at least positions of the left white line  1   a  and the right white line  1   b  of the host vehicle traveling lane and calculates at least sensing results of the positions of the left white line and the right white line of the host vehicle traveling lane. 
     Further, the sensing results of the positions of the left white line and the right white line of the host vehicle traveling lane are sent to the white line position unifying unit  330  as the data  820   b.    
     The white line position unifying unit  330  unifies the data  820   b  including the sensing results of the positions of the left white line and the right white line of the host vehicle traveling lane and the data  810   d  including the map-based positions of the left white line and the right white line of the host vehicle traveling lane to calculate a unification result of the position of the left white line and a unification result of the position of the right white line of the host vehicle traveling lane, and sends the unification results as the data  830   d . To unify the two data  820   b  and  810   d , it is desirable to use an αβ filter or a Kalman filter, but other methods may be used. 
     The data  830   d  is input to the white line position estimation unit  340 , and the white line position estimation unit  340  calculates an estimation result of the position of the left white line of the host vehicle traveling lane and an estimation result of the position of the right white line of the host vehicle traveling lane at a time T 0 +ΔT. The estimation result of the position of the left white line of the host vehicle traveling lane and the estimation result of the position of the right white line of the host vehicle traveling lane are sent to the white line position unifying unit  330  as the data  830   f . Therefore, the white line position unifying unit  330  unifies the data  820   b ,  810   d , and  830   f  at or after the time T 0 +ΔT to calculate a unification result of the position of the left white line of the host vehicle traveling lane and a unification result of the position of the right white line of the host vehicle traveling lane and sends the unification results as the data  830   d.    
     Concurrently with the above operation, the white line position unifying unit  330  calculates a unification error obtained in unification of the two data  820   b  and  810   d  and sends the unification error as the data  830   e  at the time T 0 +ΔT. For example, in a case where a Kalman filter is used, a size of an error ellipse can be used as the unification error. 
     The data  830   e  is sent to the host vehicle position estimation error calculation unit  220 , is unified with error information of the latitude and longitude of location of the host vehicle at the time T 0 +ΔT by the host vehicle position estimation error calculation unit  220 , is calculated as an error  4   c  of a road distance to the map-based stop line at the time T 0 +ΔT, and is sent as data  810   c  to the stop line detection processing unit  130   a  provided in the second sensor  10   b.    
     Through the above operation, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the error  4   c  of the road distance to the map-based stop line becomes smaller with passage of time, and the error  4   c  can be corrected based on a result of comparison between the sensing results of the positions of the left white line and the right white line of the host vehicle traveling lane and the map-based positions of the left white line and the right white line of the host vehicle traveling lane. Therefore, the error  4   c  of the road distance to the stop line is smaller than that in the first embodiment and the second embodiment. Accordingly, the stop line detection area  3  is further reduced. This increases a rate of detection of the stop line  2  as compared with the first embodiment and the second embodiment. 
     In the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the positions of the left white line and the right white line of the host vehicle traveling lane are used as an example of a second feature, but the second feature may be a pedestrian crossing, a road surface marker such as a pedestrian crossing notice marker, a three-dimensional object on a road such as a sign, a signboard, a traffic light, a median, or a guardrail, or feature points of a building or a construction. 
     Further, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the white line detection processing unit  140  is provided in the second sensor  10   b , but the stop line detection processing unit  130   a  may be provided in the third fusion unit  30   c.    
     Fourth Embodiment 
       FIG. 6  is a functional block diagram of a stop line detection system according to the fourth embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 6 . Constituent elements similar to those in the above embodiments are given identical reference signs, and detailed description thereof is omitted. 
     In  FIG. 6, 20   b  is a second information source,  150  is V2X (e.g., vehicle-to-vehicle communication, road-to-vehicle communication, cloud-to-vehicle communication), and  800   d  is data sent from the V2X. 
     The data  800   d  sent from the V2X  150  includes at least latitude and longitude information of a stop line detected by a vehicle other than a host vehicle. A distance calculation unit  210  for calculating a distance to a stop line calculates a road distance to a map-based stop line and an error  4   d  of the road distance to the map-based stop line based on the data  800   a  to  800   d.    
     Through the above operation, the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system can calculate a road distance to a map-based stop line more accurately than the above embodiments, for example, in a case where an error of generated latitude and longitude information of a stop line registered in map information of the data  800   a  sent from a map information acquisition unit  100  is large, in a case where the latitude and longitude information has not been updated, or in a case where deviation occurs due to a crustal change such as an earthquake. This assures limiting accuracy of a stop line detection area  3  generated by a stop line detection processing unit  130   a , thereby increasing robustness of improvement of a stop line detection rate as compared with the above embodiments. 
     Fifth Embodiment 
       FIG. 7  is a functional block diagram of a stop line detection system according to the fifth embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 7 . Constituent elements similar to those in the above embodiments are given identical reference signs, and detailed description thereof is omitted. 
     In  FIG. 7, 30   d  is a fourth fusion unit,  130   b  is a stop line detection processing unit provided in a sensor  10   a ,  500   a  is a learning unit,  600   a  is a storage unit, and the learning unit  500   a  and the storage unit  600   a  are included in the fourth fusion section  30   d.    
     Further,  510  is a stop line position and feature learner,  610  is a stop line position storage area, and  620  is a stop line feature storage area, and the stop line position and feature learner  510  is included in the learning unit  500   a , and the stop line position storage area  610  and the stop line feature storage area  620  are included in the storage unit  600   a.    
     In  FIG. 7, 810   e  is data sent from a map information processing calculation unit  200   a ,  820   c  is data sent from the stop line detection processing unit  130   b ,  840   a  to  840   d  are data sent from the learning unit  500   a , and  850   a  is data sent from the storage unit  600   a.    
     The stop line detection processing unit  130   b  provided in the sensor  10   a  extracts features of a detected stop line in addition to data  820   a  including a sensing result of a road distance to the stop line described in the above embodiments and sends the data  820   c  including the features of the stop line. The features of the stop line include at least a length of the stop line and a degree of fading. 
     In a case where a host vehicle approaches a certain stop line  2  for the first time, the learning unit  500   a  starts the following operation in accordance with data  810   b  including a processing operation start flag. Based on the data  820   c  and data  830   a  including a unification result of a road distance to the stop line sent from a stop line position unifying unit  310 , the stop line position and feature learner  510  learns a position and features of the stop line and send the position and features of the stop line to the storage unit  600   a  as the data  840   a . The data  840   a  input to the storage unit  600   a  is stored in the stop line position storage area  610  and the stop line feature storage area  620 . 
     In a case where the host vehicle approaches the stop line  2  next time and thereafter, the map information processing calculation unit  200   a  sends the data  810   b  including the processing operation start flag and the data  810   e  including the positional information of the stop line  2  to the learning unit  500   a . Based on the data  810   e , the learning unit  500   a  sends an inquiry about the position and the features regarding the stop line  2  to the storage unit  600   a  as the data  840   b.    
     In accordance with the data  840   b , the storage unit  600   a  searches the stop line position storage area  610  and the stop line feature storage area  620  for the position and features regarding the stop line  2  and sends the position and features regarding the stop line  2  to the learning unit  500   a  as the data  850   a . Based on the data  850   a  including the position and features regarding the stop line  2  acquired from the storage unit  600   a , the learning unit  500   a  sends the stored information of the position regarding the stop line  2  as the data  840   c  to a distance calculation unit  210  for calculating a distance to a stop line and sends the stored information of the features regarding the stop line  2  as the data  840   d  to the stop line detection processing unit  130   b.    
     The distance calculation unit  210  for calculating a distance to the stop line unifies data  800   a  to  800   c  sent from an information source  20   a  and the data  840   c , calculates a road distance to a map-based stop line and an error  4   e  of the road distance to the map-based stop line, and sends the road distance to the map-based stop line and the error  4   e  of the road distance to the map-based stop line to the stop line detection processing unit  130   b  as the data  810   a.    
     The stop line detection processing unit  130   b  generates a stop line detection area  3  based on the data  810   a  including the road distance to the map-based stop line and the error  4   e  of the road distance to the map-based stop line sent from the distance calculation unit  210  for calculating a distance to the stop line. Concurrently, the stop line detection processing unit  130   b  detects the stop line  2  in the stop line detection area  3  based on the data  840   d  including the stored information of the stop line features sent from the learning unit  500   a . Further, the stop line detection processing unit  130   b  extracts features of the detected stop line and sends the data  820   c  including the features of the stop line in addition to the data  820   a  including a sensing result of the road distance to the stop line. 
     Based on the data  820   c  and the data  830   a  including the unification result of the road distance to the stop line sent from the stop line position unifying unit  310 , the learning unit  500   a  causes the stop line position and feature learner  510  to learn a position and features of the stop line and send the position and features of the stop line to the storage unit  600   a  as the data  840   a . The data  840   a  input to the storage unit  600   a  is stored in the stop line position storage area  610  and the stop line feature storage area  620 . 
     Through the above operation, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the error  4   e  of the road distance to the map-based stop line becomes smaller with passage of time and in accordance with the number of times the host vehicle passes the stop line, and the stop line detection area  3  is reduced accordingly. This can increase a stop line detection rate as compared with the above embodiments. Further, since stop line detection performance is improved by using stored information of stop line features, a stop line detection rate can be increased as compared with the above embodiments. 
     Note that in a case where stored information of stop line features acquired by a vehicle other than a host vehicle is acquired by using the V2X  150  described in the fourth embodiment for the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, efficiency of learning of stop line features is further increased, and a stop line detection rate can be increased as compared with the first to fourth embodiments. 
     Sixth Embodiment 
       FIG. 8  is a functional block diagram of a stop line detection system according to the present embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 8 . Constituent elements similar to those in the above embodiments are given identical reference signs, and detailed description thereof is omitted. 
     In  FIG. 8, 10   c  is a third sensor, and  30   e  is a fifth fusion unit. In  FIG. 8, 160  is a pedestrian crossing recognition unit,  170  is a sign recognition unit, and the pedestrian crossing recognition unit  160  and the sign recognition unit  170  are provided in the third sensor  10   c.    
     In  FIG. 8, 700  is a data unifying unit,  710  is a stop line position estimation unit, and the data unifying unit  700  and the stop line position estimation unit  710  are included in the fifth fusion unit  30   e . In  FIG. 8, 820   d  is data sent from the pedestrian crossing recognition unit  160 ,  820   e  is data sent from the sign recognition unit  170 , and data  860   a  to  860   c  are data sent from the data unifying unit  700 . 
     When the pedestrian crossing recognition unit  160  included in the third sensor  10   c  recognizes a pedestrian crossing ahead on a host vehicle traveling lane, the pedestrian crossing recognition unit  160  calculates a distance L 1  to an end of the pedestrian crossing closer to the host vehicle and sends the distance L 1  to the data unifying unit  700  as the data  820   d . Further, when the sign recognition unit  170  included in the third sensor  10   c  recognizes a sign ahead of the host vehicle, the sign recognition unit  170  calculates a type of the sign and a distance L 2  to the sign and sends the type and the distance L 2  to the data unifying unit  700  as the data  820   e.    
     In a case where the distance L 1  to the end of the pedestrian crossing closer to the host vehicle included in the data  820   d  becomes equal to or less than a predetermined determination value, the data unifying unit  700  sends a detection operation start flag and the distance L 1  to the end of the pedestrian crossing closer to the host vehicle to the stop line position estimation unit  710  as the data  860   a.    
     The stop line position estimation unit  710  starts the following operation in accordance with the detection operation start flag included in the data  860   a . The stop line position estimation unit  710  calculates an estimated distance L 1 -ΔL to the stop line by subtracting a predetermined distance ΔL between an end of a pedestrian crossing closer to the host vehicle and a stop line from the distance L 1  to the end of the pedestrian crossing closer to the host vehicle included in the data  860   a . Concurrently, the stop line position estimation unit  710  calculates an error  4   f  of the estimated distance to the stop line. 
     The error  4   f  of the estimated distance to the stop line is desirably a value obtained by adding a predetermined variation of the distance ΔL between a pedestrian crossing and a stop line to a predetermined error according to detection accuracy of the sensor  10   a  and the third sensor  10   c . Further, the stop line position estimation unit  710  sends the estimated distance L 1 -ΔL to the stop line and the error  4   f  of the estimated distance to the stop line to a stop line detection processing unit  130   a  as data  810   a  and concurrently sends a detection operation start flag to the stop line detection processing unit  130   a  as data  810   b.    
     Meanwhile, in a case where the type of the sign included in the data  820   e  is “stop” and the distance L 2  to the sign included in the data  820   e  is equal to or less than a predetermined determination value, the data unifying unit  700  sends an operation start flag and the distance L 2  to the sign to the stop line position estimation unit  710  as the data  860   b.    
     The stop line position estimation unit  710  starts the following operation in accordance with the detection operation start flag included in the data  860   b . The stop line position estimation unit  710  calculates an estimated distance L 3  to a stop line from the distance L 2  to the sign included in the data  860   a . The distance L 2  to the sign and the estimated distance L 3  to the stop line may be equal to each other. 
     Concurrently, the stop line position estimation unit  710  calculates an error  4   f  of the estimated distance to the stop line. The error  4   f  of the estimated distance to the stop line is desirably a predetermined error according to detection accuracy of the first sensor  10   a  and the third sensor  10   c . Further, the stop line position estimation unit  710  sends the estimated distance L 3  to the stop line and the error  4   f  of the estimated distance to the stop line to the stop line detection processing unit  130   a  as the data  810   a  and concurrently sends a detection operation start flag to the stop line detection processing unit  130   a  as the data  810   b.    
     Note that the stop line position estimation unit  710  starts operation in accordance with the detection operation start flag included in the data  860   a  OR the detection operation start flag included in the data  860   b . Further, in the operation of the stop line detection processing unit  130   a , a range of the stop line detection area  3  is a logical disjunction (OR) or a logical conjunction (AND) of a range limited based on the estimated distance L 1 -ΔL to the stop line and the error  4   f  of the estimated distance to the stop line and a range limited based on the estimated distance L 3  to the stop line and the error  4   f  of the estimated distance to the stop line. 
     The logical disjunction (OR) is desirable to increase a rate of inclusion of the stop line in the stop line detection area  3  by expanding the range of the stop line detection area  3 . Meanwhile, the logical conjunction (AND) is desirable to increase a rate of detection by narrowing the range of the stop line detection area  3 . 
     Through the above operation, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the stop line detection area  3  can be limited in the stop line detection processing unit  130   a  provided in the sensor  10   a  even in a case where the map information acquisition unit  100  does not operate or is not provided. This can increase a stop line detection rate. 
     Although a pedestrian crossing and a sign are used as information for limiting the stop line detection area  3  in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, a road surface marker such as a pedestrian crossing notice marker, a three-dimensional object on a road such as a signboard, a traffic light, a median, or a guardrail, or feature points of a building or a construction may be used. 
     Further, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the pedestrian crossing recognition unit  160  and the sign recognition unit  170  are provided in the third sensor  10   c , but the pedestrian crossing recognition unit  160  and the sign recognition unit  170  may be provided in the sensor  10   a  or the fifth fusion unit  30   e . Furthermore, functions of the pedestrian crossing recognition unit  160  and the sign recognition unit  170  may be realized by combining one or more sensors other than the sensor  10   a  (first sensor) and the sensor  10   c  (third sensor). 
     Seventh Embodiment 
       FIG. 9  is a functional block diagram of a stop line detection system according to the seventh embodiment and an autonomous driving method using the stop line detection system. Operation of the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system will be described with reference to  FIG. 9 . Constituent elements similar to those in the above embodiments are given identical reference signs, and detailed description thereof is omitted. 
     In  FIG. 9, 10   d  is a fourth sensor, and  30   f  is a sixth fusion unit. In  FIG. 9, 180  is a vehicle detection unit, and the vehicle detection unit  180  is provided in the fourth sensor  10   d . In  FIG. 9, 600   b  is a storage unit,  630  is an estimated distance storage region in which an estimated distance to a front end of a preceding vehicle at a time when the preceding vehicle stops is stored, and the estimated distance storage region  630  is included in the storage unit  600   b.    
     In  FIG. 9, 720  is a distance estimation unit that estimates a distance to the front end of the preceding vehicle,  730  is a distance calculation unit that calculates a distance to a position where the preceding vehicle has been stopped at a current time, and  740  is a host vehicle stop position unifying unit. In  FIG. 9, 820   f  is data sent from the vehicle detection unit  180 ,  830   g  is data sent from the distance estimation unit  720  for estimating a distance to the front end of the preceding vehicle,  830   h  is data sent from the distance calculation unit  730  for estimating a distance to the position at which the preceding vehicle has stopped at the current time,  830   i  is data sent from the host vehicle stop position unifying unit  740 , and  840   e  is data sent from the storage unit  600   b.    
     The vehicle detection unit  180  provided in the fourth sensor  10   d  detects a preceding vehicle traveling ahead on a host vehicle traveling lane, calculates speed, type, width, height, and distance to a rear end of the preceding vehicle, and sends the speed, type, width, height, and distance to the rear end of the preceding vehicle as the data  820   f.    
     The distance estimation unit  720  for estimating a distance to the front end of the preceding vehicle estimates a length of the preceding vehicle based on the type, width, and height of the preceding vehicle included in the data  820   f . Further, the distance estimation unit  720  calculates an estimated distance to a front end of the preceding vehicle by adding an estimated value of the length of the preceding vehicle to the distance to the rear end of the preceding vehicle included in the data  820   f . Furthermore, the distance estimation unit  720  sends the estimated distance to the front end of the preceding vehicle and the speed of the preceding vehicle as the data  830   g.    
     Based on the data  830   g , the storage unit  600   b  causes a time T 1  at which the preceding vehicle stops and an estimated distance L 4  to the front end of the preceding vehicle at the time TI to be stored in the estimated distance storage region  630 . Further, the storage unit  600   b  sends stored data regarding the time T 1  at which the preceding vehicle stops and the estimated distance L 4  to the front end of the preceding vehicle at the time TI to the distance calculation unit  730  for calculating a distance to the position at which the preceding vehicle has stopped at the current time as the data  840   e.    
     The map information processing calculation unit  200   a  sends data  810   f  including at least a speed of the host vehicle to the distance calculation unit  730  for calculating a distance to the position at which the preceding vehicle has stopped at the current time. 
     The distance calculation unit  730  for calculating a distance to the position at which the preceding vehicle has stopped at the current time calculates an estimated distance L 5  to a position where the preceding vehicle has been stopped at a time T 2  based on the two data  810   f  and  840   e . Specifically, the estimated distance L 5  can be obtained by the following Expression (1) when the speed of the host vehicle is a constant value V between the times T 1  and T 2 . 
         L 5= L 4−( T 2− T 1)× V   (1)
 
     Further, the distance calculation unit  730  sends the estimated distance L 5  to the position where the preceding vehicle has been stopped at the time T 2  to the host vehicle stop position unifying unit  740  as the data  840   h.    
     The host vehicle stop position unifying unit  740  unifies data  830   a  including a unification result of a road distance to a stop line at the time T 2  and the data  840   h  including the estimated distance L 5  to the position where the preceding vehicle has been stopped at the time T 2  and sends the unified data to a planning/judgment unit  40  as the data  830   i . In the unification, for example, in a case where the data  820   a  is not sent from a stop line detection processing unit  130   a , processing for increasing a weight of the data  840   h  is executed. 
     Through the above operation, in the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, information for stopping the host vehicle can be calculated and sent to the planning/judgment unit  40  even in a case where a stop line ahead cannot be detected by the sensor  10   a  due to a preceding vehicle. This can improve safety of driving. 
     In the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, the vehicle detection unit  180  is provided in the fourth sensor  10   d , but may be provided in the sensor  10   a  or the sixth fusion unit  30   f . Further, the functions of the vehicle detection unit  180  may be realized by combining one or more sensors other than the first and fourth sensors  10   a  and  10   d.    
     Eighth Embodiment 
       FIG. 10  illustrates a technical outline of a stop line detection system according to the eighth embodiment and an autonomous driving method using the stop line detection system. In  FIG. 10, 5  is a virtual stop line, which is a line connecting ends, on a side closer to a host vehicle, of a lane that intersects a host vehicle driving lane at a traffic intersection. 
     Although a stop line actually drawn on a road surface is used as a feature in the first to seventh embodiments, the virtual stop line  5  may be used as a feature in a case where stop line detection using a sensor is difficult at a traffic intersection of poor visibility, at night, or in the rain. The feature is not limited to a stop line actually drawn on a road surface and may be a virtual stop line that is not actually drawn on a road surface. 
     In the stop line detection system according to the present embodiment and the autonomous driving method using the stop line detection system, information for stopping a host vehicle can be calculated and sent to a planning/judgment unit  40  even in a case where stop line detection using a sensor is difficult at a traffic intersection of poor visibility, at night, or in the rain as described above. This can improve safety of driving. The virtual stop line  5  may be calculated from stop information of other vehicles obtained from V2X  150  or from stored past stop information of the host vehicle. 
     In the first to eighth embodiments of the stop line detection system and the autonomous driving method using the stop line detection system, the first to fourth sensors may be any sensor such as a camera (visible light, near infrared, far infrared), LiDAR, laser radar, radio wave radar, or sonar. 
     In the description of the operation of the stop line detection system and the autonomous driving method using the stop line detection system according to the first to eighth embodiments, a processing delay time in the functional blocks  100  to  340  and a communication delay time between functional blocks are ignored in the operation start time of the stop line position unifying unit  310 , the operation start times of the stop line detection processing units  130   a  and  130   b , the operation start time of the learning unit  500   a , and the sending times of the data  800  to  850 . In an actual system, the operation start times and the data sending times may be determined in consideration of the processing delay time and the communication delay time. 
     Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, the above embodiments have been described in detail to explain the present invention in an easy-to-understand manner and are not necessarily limited to one having all the described elements. Further, one or more of elements of one embodiment may be replaced with an element of another embodiment. Further, an element of one embodiment may be added to elements of another embodiment. Moreover, as for one or more of elements of each embodiment, addition, deletion, or substitution of another element is possible. 
     REFERENCE SIGNS LIST 
     
         
           1  white line 
           2  stop line 
           3  stop line detection area 
           4  error of road distance to map-based stop line 
           5  virtual stop line 
           10  sensor 
           20  information source 
           30  fusion unit 
           40  planning/judgment unit 
           100  map information acquisition unit 
           110  locator 
           120  host vehicle information acquisition unit 
           130  stop line detection processing unit 
           140  white line detection processing unit 
           150  V2X 
           160  pedestrian crossing recognition unit 
           170  sign recognition unit 
           180  vehicle detection unit 
           200  map information processing calculation unit 
           210  distance calculation unit for calculating distance to 
         stop line 
           300  map information-sensing result unifying unit 
           310  stop line position unifying unit 
           400  track planning unit 
           410  speed planning unit 
           500  learning unit 
           510  stop line position and feature learner 
           520  other vehicle stop position learner 
           600  storage unit 
           610  stop line position storage region 
           620  stop line feature storage region 
           630  estimated distance storage region in which estimated distance to front end of preceding vehicle at time at which preceding vehicle stops is stored 
           700  data unifying unit 
           710  stop line position estimation unit 
           720  distance estimation unit for estimating distance to front end of preceding vehicle 
           730  distance calculation unit for calculating distance to position at which preceding vehicle has been stopped at current time 
           740  host vehicle stop position unifying unit 
           900  signal processing step 
           910  determination processing step