JP5220479B2 - Navigation device and vehicle position update method - Google Patents

Description

  The present invention relates to a navigation apparatus and a vehicle position update method, and more particularly to a navigation apparatus and a vehicle position update method for displaying a vehicle position mark indicating a vehicle position on a map.

  In general, the position of a vehicle in a car navigation device is specified by GPS (Global Positioning System), an autonomous navigation technique using an autonomous navigation sensor, a map matching technique, or the like (see, for example, Patent Document 1). One of the map matching techniques is a projection method. The projection method is a method of searching for a point on the road that can be projected under a predetermined condition from a measurement position measured by GPS or autonomous navigation technology, and trying to correct the vehicle position to the point.

Note that the current position calculation device described in Patent Literature 1 calculates candidate points that are vehicle position correction candidates together with reliability, and updates the vehicle position to the candidate point with the highest reliability. Further, among candidate points other than the candidate points with the highest reliability, candidate points with a certain degree of reliability are stored to calculate new candidate points, while candidate points with a certain degree of reliability are not stored. It is to delete.
JP 08-334346 A

  However, when the conventional projection method is applied, there may be a problem that the vehicle position is corrected on a road different from the road where the vehicle actually exists. FIG. 6 is a diagram for explaining how the vehicle position is updated by a conventional projection method. According to the conventional projection method, for example, as shown in FIG. 6, at time T0, the GPS measurement position at the time T0 of the vehicle traveling at the point P0 on the road R1 in the direction of arrow A is Q0 outside the road. If it is a point, the vehicle position is correctly corrected from the point Q0 to the actual point P0 on the road R1. However, if the GPS measurement position of the vehicle moved to point P1 on the road R1 at time T1 becomes Q1 point outside the road, the vehicle position is correctly corrected from point Q1 to point P1 on the road R1. Without being corrected to the P1 ′ point on the road R2. This is because the distance D2 from the point Q1 to the road R2 is shorter than the distance D1 from the point Q1 to the road R1. The road R2 includes the actual position (P0 point) of the vehicle on the road (road R1) on which the vehicle actually traveled at the previous measurement (time T0) and the vehicle at the current measurement (time T1). A road (road R1) on which the vehicle is actually traveling, with a certain position (point S) between the actual position (point P1) of the vehicle on the road (road R1) on which the vehicle is actually traveling ) To the side closer to the measurement position (Q1 point) at the time of the current measurement (time T1).

  The present invention has been made to solve such problems. That is, an object of the present invention is to prevent erroneous correction of the vehicle position on a road different from the road where the vehicle is actually located as much as possible. Specifically, the vehicle travels with a branch point at a position between the actual position of the vehicle at the previous measurement and the actual position of the vehicle at the current measurement on the road on which the vehicle is traveling. The purpose is to prevent as much as possible the erroneous correction of the vehicle position on the other road that branches from the existing road to the side closer to the measurement position at the time of the current measurement.

  In order to solve the above-described problem, in the present invention, the distance between a GPS position that is a measurement position of a vehicle that is measured each time using GPS and a candidate road that is a candidate for which the vehicle position should be updated is a GPS that relates to the candidate road. The distance is calculated each time. In addition to the existing candidate road detected last time, a new candidate road that was not previously detected is detected this time, and the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road are detected. If it is determined that the difference is not equal to or less than the reference distance, the current GPS related to the existing candidate road is included in the expression that includes the GPS distance as a variable and calculates a higher evaluation value as the GPS distance is shorter. The evaluation value related to the existing candidate road is calculated by substituting the distance, and the evaluation value related to the new candidate road is calculated by substituting the current GPS distance related to the new candidate road into the evaluation formula. The vehicle position is updated on the road. On the other hand, in the case where a new candidate road that was not previously detected in addition to the previously detected existing candidate road is detected this time, the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road When it is determined that the difference is equal to or less than the reference distance, the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road are used instead of the current GPS distance related to the existing candidate road in the evaluation formula. The evaluation value related to the existing candidate road is calculated by substituting the difference, and the evaluation value related to the new candidate road is calculated by substituting the current GPS distance related to the new candidate road into the evaluation formula. The vehicle position is updated on the road.

  According to the present invention configured as described above, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, the previous time related to the existing candidate road calculated last time When the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels as it is on the existing candidate road If a value larger than the difference assumed in the above is set as the reference distance, the difference is equal to or less than the reference distance. Therefore, instead of the current GPS distance related to the existing candidate road, the difference between the previous GPS distance related to the existing candidate road calculated last time and the current GPS distance related to the existing candidate road calculated this time is substituted into the evaluation formula. The evaluation value related to the candidate road is calculated. In addition, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, the previous calculation is substituted into the evaluation formula instead of the current GPS distance related to the existing candidate road The difference between the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road calculated this time is likely to be smaller than the current GPS distance related to the new candidate road. This is because the difference when the vehicle travels on the existing candidate road as it is without entering the new candidate road at the branch point on the existing candidate road usually tends to be an extremely small value. Thereby, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, the evaluation value related to the existing candidate road is likely to be higher than the evaluation value related to the new candidate road. Therefore, the vehicle position is easily updated on the existing candidate road instead of the new candidate road. That is, erroneous correction of the vehicle position on a new candidate road different from the existing candidate road where the vehicle is actually located can be prevented as much as possible.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a navigation device 10 according to an embodiment of the present invention. As shown in FIG. 1A, the navigation device 10 includes a storage medium control unit 21, a map information memory 22, a position measurement unit 23, a CPU 24 (processor), a ROM 25, a RAM 26, an operation unit 30, a display controller 31, and a video RAM 32. , A mark generation unit 33, an image composition unit 40, and a display device 50.

  The storage medium control unit 21 controls reading of a storage medium such as the DVD-ROM 4. The DVD-ROM 4 stores various map data necessary for map display, route search, and the like. The storage medium control unit 21 temporarily stores the map data read from the DVD-ROM 4 in the map information memory 22.

  The position measurement unit 23 includes an autonomous navigation sensor, a GPS receiver, a position calculation CPU, and the like, and measures the current position of the vehicle. The autonomous navigation sensor is a vehicle speed sensor (distance sensor) that outputs a single pulse for each predetermined travel distance to detect the moving distance of the vehicle, and an angular velocity sensor such as a vibration gyro that detects the rotation angle (moving direction) of the vehicle. (Relative orientation sensor). The autonomous navigation sensor detects the relative position and direction of the vehicle by these vehicle speed sensor and angular velocity sensor.

  The position calculation CPU calculates the absolute vehicle position (estimated vehicle position) and vehicle direction of the own vehicle based on the relative position and direction data of the own vehicle output from the autonomous navigation sensor. The GPS receiver receives radio waves transmitted from a plurality of GPS satellites by a GPS antenna and performs a three-dimensional positioning process or a two-dimensional positioning process to calculate the absolute position and direction of the vehicle (the vehicle direction is The calculation is based on the current vehicle position of the vehicle and the vehicle position of the vehicle one sampling time ΔT before). The position measuring unit 23 supplies the measured current position of the vehicle to the CPU 24 and stores it in the RAM 26 as a traveling locus of the vehicle. Note that the RAM 26 temporarily stores data obtained in the course of various processes and data obtained as a result of various processes in addition to the travel locus of the vehicle.

  The CPU 24 controls the navigation device 10. The CPU 24 functions as, for example, a candidate road detection unit of the present invention, a GPS distance calculation unit of the present invention, a reference distance determination unit of the present invention, an evaluation value calculation unit of the present invention, and a vehicle position update unit of the present invention. Details of operations of the candidate road detection unit, the GPS distance calculation unit, the reference distance determination unit, the evaluation value calculation unit, and the vehicle position update unit of the present invention will be described later.

  The ROM 25 stores various programs. For example, as shown in FIG. 1B, the ROM 25 has a candidate road detection program 100 that causes the CPU 24 to function as a candidate road detection unit of the present invention, and a GPS distance calculation program 110 that causes the CPU 24 to function as a GPS distance calculation unit of the present invention. A reference distance determination program 120 that causes the CPU 24 to function as a reference distance determination unit of the present invention, an evaluation value calculation program 130 that causes the CPU 24 to function as an evaluation value calculation unit of the present invention, and a vehicle that causes the CPU 24 to function as a vehicle position update unit of the present invention The location update program 140 and the like are stored.

  The operation unit 30 includes a remote controller, a touch panel, a joystick, and the like. The user performs various settings / operations on the navigation device 10 via the operation unit 30. The display controller 31 generates map image data necessary for display on the display device 50 based on the map data stored in the map information memory 22. The video RAM 32 temporarily stores map image data generated by the display controller 31. That is, the map image data generated by the display controller 31 is temporarily stored in the video RAM 32, and the map image data for one screen is read and output to the image composition unit 40.

  The mark generation unit 33 generates and outputs a vehicle position mark displayed at the vehicle position of the host vehicle, various landmarks displaying a gas station, a convenience store, and the like. The image composition unit 40 synthesizes and outputs various images. Specifically, the map image data output from the video RAM 32 is combined with the image data output from the mark generator 33 to perform image synthesis, and the synthesized image data is output to the display device 50.

  Hereinafter, the CPU 24 functioning as a candidate road detection unit of the present invention (hereinafter simply referred to as “candidate road detection unit 200”), and the CPU 24 functioning as a GPS distance calculation unit of the present invention (hereinafter simply referred to as “GPS distance calculation unit 210”). ), A CPU 24 functioning as a reference distance determination unit of the present invention (hereinafter simply referred to as “reference distance determination unit 220”), and a CPU 24 functioning as an evaluation value calculation unit of the present invention (hereinafter simply referred to as “evaluation value calculation unit 230”). And the details of the operation of the CPU 24 (hereinafter simply referred to as “vehicle position update unit 240”) functioning as the vehicle position update unit of the present invention will be described. FIG. 2 is a diagram for explaining the candidate road detection unit 200, the GPS distance calculation unit 210, the reference distance determination unit 220, the evaluation value calculation unit 230, and the vehicle position update unit 240 of the present embodiment.

  As shown in FIG. 2, the candidate road detection unit 200 obtains vehicle position and vehicle direction data (hereinafter referred to as “GPS position”) by a GPS receiver at each predetermined timing (hereinafter referred to as “reference timing”). Obtained from the position measurement unit 23 as the measurement position of the vehicle. When the candidate road detection unit 200 acquires the measurement position of the vehicle from the position measurement unit 23, the candidate road detection unit 200 refers to the GPS position acquired from the position measurement unit 23 and the map data stored in the map information memory 22, and determines the vehicle position. Roads that are candidates to be updated (hereinafter referred to as “candidate roads”) are detected. When the candidate road detection unit 200 detects the candidate road, the candidate road detection unit 200 stores the GPS position acquired from the position measurement unit 23 and the detected candidate road (information for specifying the candidate road) in the RAM 26, and the GPS position and the candidate road. A notification (hereinafter, referred to as “GPS distance calculation notification”) that the distance (hereinafter referred to as “GPS distance”) should be calculated is supplied to the GPS distance calculation unit 210.

  The GPS distance calculation unit 210 acquires a GPS distance calculation notification from the candidate road detection unit 200 at each reference timing. When the GPS distance calculation unit 210 acquires the GPS distance calculation notification from the candidate road detection unit 200, the GPS distance calculation unit 210 refers to the map data stored in the map information memory 22, the GPS position stored in the RAM 26, and the candidate road, Is calculated. When calculating the GPS distance, the GPS distance calculation unit 210 stores the calculated GPS distance in the RAM 26 in association with the GPS position.

  In addition, when the GPS distance calculation unit 210 acquires the GPS distance calculation notification from the candidate road detection unit 200, the candidate road detection unit 200 previously detected (detected at the previous reference timing) (hereinafter, “existing candidate road”). In addition to existing candidate roads in RAM 26, new candidate roads have been detected (detected at the current reference timing) this time. Whether or not is stored is determined. When it is determined that the candidate road detection unit 200 has detected the new candidate road in addition to the existing candidate road this time, the GPS distance calculation unit 210 determines the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road. Of the difference (hereinafter referred to as “existing candidate road GPS distance difference”) and the reference distance (hereinafter referred to as “reference distance determination notification”) are supplied to the reference distance determination unit 220. The reference distance is set to a value larger than the GPS distance difference that is assumed when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is. To do.

  On the other hand, when the candidate road detection unit 200 determines that the new candidate road is not detected this time in addition to the existing candidate road, the GPS distance calculation unit 210 notifies that the evaluation value of the candidate road should be calculated (hereinafter, “ The evaluation value calculation instruction notification ”is supplied to the evaluation value calculation unit 230.

  The reference distance determination unit 220 acquires a reference distance determination notification from the GPS distance calculation unit 210 when a new candidate road is detected by the GPS distance calculation unit 210 in addition to the existing candidate roads. When the reference distance determination unit 220 obtains the reference distance determination notification from the GPS distance calculation unit 210, the reference distance determination unit 220 refers to the previous GPS distance and the current GPS distance related to the existing candidate road stored in the RAM 26, and the existing candidate road Calculate the GPS distance difference. When calculating the existing candidate road GPS distance difference, the reference distance determination unit 220 compares the calculated existing candidate road GPS distance difference with the reference distance. The reference distance determination unit 220 supplies an evaluation value calculation instruction notification to the evaluation value calculation unit 230 when it is determined that the calculated existing candidate road GPS distance difference is not less than the reference distance. On the other hand, when it is determined that the calculated existing candidate road GPS distance difference is equal to or smaller than the reference distance, the reference distance determination unit 220 supplies the existing candidate road GPS distance difference to the evaluation value calculation unit 230 together with the evaluation value calculation instruction notification. .

  The evaluation value calculation unit 230 acquires an evaluation value calculation instruction notification from the GPS distance calculation unit 210 or the reference distance determination unit 220 for each reference timing. Specifically, the evaluation value calculation unit 230 acquires an evaluation value calculation instruction notification from the GPS distance calculation unit 210 when a new candidate road is not detected in addition to the existing candidate roads. In addition, when a new candidate road is detected in addition to the existing candidate road, and the difference between the existing candidate road GPS distances is not less than or equal to the reference distance, the reference distance determination unit 220 determines that the evaluation value calculation instruction notification is the reference distance determination. Obtained from the unit 220. In addition, when a new candidate road is detected in addition to the existing candidate road, and the existing candidate road GPS distance difference is equal to or less than the reference distance, the reference distance determination unit 220 includes the existing candidate along with the evaluation value calculation instruction notification. A road GPS distance difference is acquired from the reference distance determination unit 220.

  The evaluation value calculation unit 230 is an expression including the GPS distance as a variable when only the evaluation value calculation instruction notification is acquired from the GPS distance calculation unit 210 (when a new candidate road is not detected in addition to the existing candidate road). The current GPS distance related to the existing candidate road stored in the RAM 26 is substituted into the evaluation formula for calculating a higher evaluation value as the GPS distance is shorter, and the evaluation value related to the existing candidate road is calculated.

  When the evaluation value calculation unit 230 acquires only the evaluation value calculation instruction notification from the reference distance determination unit 220 (when a new candidate road is detected in addition to the existing candidate road, and the existing candidate road GPS distance difference is the reference distance If not, the current GPS distance related to the existing candidate road stored in the RAM 26 is substituted into the evaluation formula to calculate the evaluation value related to the existing candidate road, and the current time related to the new candidate road stored in the RAM 26 The GPS distance is substituted into the evaluation formula, and the evaluation value related to the new candidate road is calculated.

  The evaluation value calculation unit 230 obtains an existing candidate road GPS distance difference from the reference distance determination unit 220 together with the evaluation value calculation instruction notification (when a new candidate road is detected in addition to the existing candidate road and the existing candidate road When the GPS distance difference is equal to or less than the reference distance), the existing candidate road GPS distance difference acquired from the reference distance determination unit 220 is substituted into the evaluation formula instead of the current GPS distance related to the existing candidate road stored in the RAM 26. Then, the evaluation value related to the existing candidate road is calculated, and the current GPS distance related to the new candidate road stored in the RAM 26 is substituted into the evaluation formula to calculate the evaluation value related to the new candidate road.

  When the evaluation value related to the candidate road (existing candidate road / existing candidate road and new candidate road) is calculated, the evaluation value calculating unit 230 identifies the candidate road having the highest evaluation value. When the candidate road that has the highest evaluation value is identified, the evaluation value calculation unit 230 supplies the candidate road that has the identified highest evaluation value to the vehicle position update unit 240.

  The vehicle position update unit 240 acquires the candidate road that has the highest evaluation value from the evaluation value calculation unit 230. When the candidate road having the highest evaluation value is acquired from the evaluation value calculation unit 230, the vehicle position update unit 240 refers to the candidate road acquired from the value calculation unit 230 and the GPS position stored in the RAM 26, The vehicle position is updated on the candidate road. When the vehicle position is updated, the vehicle position update unit 240 supplies the updated vehicle position to the mark generation unit 33. The mark generation unit 33 generates a vehicle position mark at the updated vehicle position and supplies the vehicle position mark to the image composition unit 40, and the image composition unit 40 outputs the vehicle position mark to the display device 50.

  Hereinafter, the operation of the navigation device 10 will be described. FIG. 3 is a flowchart showing an operation example of the navigation apparatus 10 shown in FIG. The flowchart shown in FIG. 3 starts when the navigation device 10 is activated (for example, powered on).

  In FIG. 3, the candidate position specifying unit 210 determines whether or not the reference timing has come (step S100). When the candidate position specifying unit 210 determines that it is not the reference timing (step S100: No), the candidate position specifying unit 210 repeats the same processing until the reference timing is reached. On the other hand, when the candidate position specifying unit 210 determines that the reference timing has come (step S100: Yes), the candidate position specifying unit 210 acquires the GPS position from the position measuring unit 23 as the vehicle measurement position. The candidate road detection unit 200 that has acquired the GPS position refers to the GPS position acquired from the position measurement unit 23 and the map data stored in the map information memory 22, and detects a candidate road (step S110). When the candidate road detection unit 200 detects the candidate road, the candidate road detection unit 200 stores the GPS position acquired from the position measurement unit 23 and the detected candidate road in the RAM 26 (step S115), and sends a GPS distance calculation notification to the GPS distance calculation unit. 210 is supplied.

  The GPS distance calculation unit 210 that has acquired the GPS distance calculation notification from the candidate road detection unit 200 calculates the GPS distance by referring to the map data stored in the map information memory 22, the GPS position stored in the RAM 26, and the candidate road. (Step S120). When calculating the GPS distance, the GPS distance calculation unit 210 stores the calculated GPS distance in the RAM 26 in association with the GPS position (step S125). The GPS distance calculation unit 210 that stores the GPS distance in association with the GPS position in the RAM 26 determines whether the candidate road detection unit 200 has detected a new candidate road in addition to the existing candidate road (step S130). When the GPS distance calculation unit 210 determines that the candidate road detection unit 200 has detected a new candidate road in addition to the existing candidate roads (step S130: Yes), the GPS distance calculation unit 210 performs a reference distance determination notification. To the unit 220. On the other hand, if the GPS distance calculation unit 210 determines that the candidate road detection unit 200 has not detected a new candidate road in addition to the existing candidate roads (step S130: No), the GPS distance calculation unit 210 issues an evaluation value calculation instruction. The notification is supplied to the evaluation value calculation unit 230.

  Subsequent to step S130 (Yes), the reference distance determination unit 220 that has acquired the reference distance determination notification from the GPS distance calculation unit 210 stores the previous GPS distance and the current GPS distance related to the existing candidate road stored in the RAM 26. , The existing candidate road GPS distance difference is calculated (step S140). The reference distance determination unit 220 that has calculated the existing candidate road GPS distance difference determines whether or not the calculated existing candidate road GPS distance difference is equal to or less than the reference distance (step S150). When the reference distance determination unit 220 determines that the calculated existing candidate road GPS distance difference is not less than or equal to the reference distance (step S150: No), the reference distance determination unit 220 sends an evaluation value calculation instruction notification to the evaluation value calculation unit 230. Supply. On the other hand, when the reference distance determination unit 220 determines that the calculated existing candidate road GPS distance difference is equal to or less than the reference distance (step S150: Yes), the reference distance determination unit 220 transmits the existing candidate along with the evaluation value calculation instruction notification. The road GPS distance difference is supplied to the evaluation value calculation unit 230.

  Subsequent to step S130 (No), the evaluation value calculation unit 230 that has acquired the evaluation value calculation instruction notification from the GPS distance calculation unit 210 substitutes the current GPS distance related to the existing candidate road stored in the RAM 26 into the evaluation formula. Then, the evaluation value related to the existing candidate road is calculated (step S160). The evaluation value calculation unit 230 that has calculated the evaluation value related to the candidate road (existing candidate road) identifies the candidate road (existing candidate road) that is the highest evaluation value, and identifies the candidate road (existing existing road) that has the highest evaluation value. Candidate road) is supplied to the vehicle position update unit 240.

  Subsequent to step S150 (No), the evaluation value calculation unit 230 that has acquired only the evaluation value calculation instruction notification from the reference distance determination unit 220 uses the current GPS distance related to the existing candidate road stored in the RAM 26 as an evaluation formula. Substituting and calculating an evaluation value relating to the existing candidate road (step S162), and substituting the current GPS distance relating to the new candidate road stored in the RAM 26 into the evaluation formula to calculate an evaluation value relating to the new candidate road ( Step S170). The evaluation value calculation unit 230 that has calculated the evaluation value relating to the candidate road (the existing candidate road and the new candidate road) specifies the candidate road (the existing candidate road or the new candidate road) that is the highest evaluation value, and specifies the highest Candidate roads that are evaluation values are supplied to the vehicle position update unit 240.

  Subsequent to step S150 (Yes), the evaluation value calculation unit 230 that has acquired the existing candidate road GPS distance difference from the reference distance determination unit 220 together with the evaluation value calculation instruction notification includes the current candidate road stored in the RAM 26. The existing candidate road GPS distance difference acquired from the reference distance determination unit 220 instead of the GPS distance is substituted into the evaluation formula to calculate an evaluation value related to the existing candidate road (step S164), and the new candidate road stored in the RAM 26 The current GPS distance related to is substituted into the evaluation formula to calculate the evaluation value related to the new candidate road (step S170). The evaluation value calculation unit 230 that has calculated the evaluation value relating to the candidate road (the existing candidate road and the new candidate road) specifies the candidate road (the existing candidate road or the new candidate road) that is the highest evaluation value, and specifies the highest Candidate roads that are evaluation values are supplied to the vehicle position update unit 240.

  Subsequent to step S160 or step S170, the vehicle position update unit 240 that has acquired the candidate road having the highest evaluation value from the evaluation value calculation unit 230 and the candidate road that has the highest evaluation value acquired from the value calculation unit 230 and the RAM 26 The vehicle position is updated on the candidate road which is the highest evaluation value with reference to the GPS position stored in (step S180). The vehicle position update unit 240 that has updated the vehicle position on the candidate road that has the highest evaluation value supplies the updated vehicle position to the mark generation unit 33 (step S185).

  Next, an end determination unit (not shown) determines whether or not to end the process (step S190). If the end determination unit determines that the process is finished (step S190: Yes), the flowchart ends. On the other hand, if the end determination unit determines that the process is not to be ended (step S190: No), the process returns to step S100. Note that the end determination unit determines to end the process, for example, when the navigation device 10 is powered off.

  Hereinafter, the flowchart shown in FIG. 3 will be supplementarily described. FIG. 4 is a diagram for explaining how the vehicle position is updated according to the present embodiment. For example, as shown in FIG. 4 (a), when the GPS measurement position of a vehicle traveling on point P0 on road R1 in the direction of arrow A is Q0 point outside the road at time T0 (candidate position When the specifying unit 210 acquires the GPS position Q0 from the position measuring unit 23), the candidate road detecting unit 200 detects the candidate road (road R1) (step S110), and the GPS position and the candidate road (road R1). Is stored in the RAM 26 (step S115), and a GPS distance calculation notification is supplied to the GPS distance calculation unit 210.

  The GPS distance calculation unit 210 calculates the GPS distance D1 of the candidate road (road R1) (step S120) and stores it in the RAM 26 (step S125). The GPS distance calculation unit 210 determines that a new candidate road is not detected in addition to the existing candidate road (road R1) (step S130: No), and supplies an evaluation value calculation instruction notification to the evaluation value calculation unit 230. The evaluation value calculation unit 230 calculates the evaluation value relating to the existing candidate road (road R1) by substituting the GPS distance of the existing candidate road (road R1) into the evaluation formula (step S160). The evaluation value calculation unit 230 supplies the existing candidate road (road R1) having the highest evaluation value to the vehicle position update unit 240. The vehicle position update unit 240 updates the vehicle position on the existing candidate road (road R1) having the highest evaluation value (step S180). That is, the vehicle position is correctly corrected from the point Q0 to the actual point P0 on the road R1.

  Subsequently, when the GPS measurement position of the vehicle moved to the point P1 on the road R1 becomes the Q1 point outside the road at the time T1 (the candidate position specifying unit 210 acquires the GPS position Q1 from the position measurement unit 23. ), The candidate road detection unit 200 detects candidate roads (road R1 and road R2) (step S110), and stores the GPS position and candidate roads (road R1 and road R2) in the RAM 26 (step S115). At the same time, a GPS distance calculation notification is supplied to the GPS distance calculation unit 210.

  The GPS distance calculation unit 210 calculates the GPS distance D1 of the candidate road (road R1) and the GPS distance D2 of the candidate road (road R2) (step S120), and stores them in the RAM 26 (step S125). The GPS distance calculation unit 210 determines that a new candidate road (road R2) is detected in addition to the existing candidate road (road R1) (step S130: Yes), and supplies a reference distance determination notification to the reference distance determination unit 220. The reference distance determination unit 220 calculates an existing candidate road GPS distance difference (the difference “0” between the previous GPS distance D1 and the current GPS distance D1) of the existing candidate road (road R1) (step S140). The reference distance determination unit 220 determines that the existing candidate road GPS distance difference “0” of the road R1 is equal to or less than the reference distance X (step S150: Yes), and the existing candidate road GPS distance of the road R1 together with the evaluation value calculation instruction notification. The difference “0” is supplied to the evaluation value calculation unit 230. The reference distance X is assumed when the vehicle travels on the existing candidate road (road R1) as it is without entering the new candidate road (R2) at the branch point S on the existing candidate road (road R1). It is a value larger than the existing candidate road GPS distance difference.

  The evaluation value calculation unit 230 substitutes the existing candidate road GPS distance difference “0” of the road R1 in the evaluation formula instead of the GPS distance D1 of the existing candidate road (road R1), and evaluates the evaluation value related to the existing candidate road (road R1). Is calculated (step S164). Further, the evaluation value calculation unit 230 calculates the evaluation value related to the new candidate road (road R2) by substituting the GPS distance D2 of the new candidate road (road R2) into the evaluation formula (step S170). The evaluation value calculation unit 230 supplies the existing candidate road (road R1) having the highest evaluation value to the vehicle position update unit 240. The vehicle position update unit 240 updates the vehicle position on the existing candidate road (road R1) having the highest evaluation value (step S180). That is, the vehicle position is correctly corrected from the point Q1 to the actual point P1 on the road R1 (not corrected to the point P1 'on the road R2).

  As described above, according to the navigation device 10 of this embodiment, the existing candidate road GPS distance assumed when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is. If a value larger than the difference is set as the reference distance, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, the existing candidate road GPS distance difference is less than the reference distance. Become. Therefore, the evaluation value for the existing candidate road is calculated by substituting the GPS distance difference for the existing candidate road into the evaluation formula instead of the current GPS distance for the existing candidate road. In addition, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels as it is, the existing candidate road GPS that is substituted into the evaluation formula instead of the current GPS distance related to the existing candidate road The distance difference tends to be smaller than the current GPS distance related to the new candidate road. This is because the GPS distance difference between the existing candidate roads when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is usually tends to be extremely small. Thereby, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, the evaluation value related to the existing candidate road is likely to be higher than the evaluation value related to the new candidate road. Therefore, the vehicle position is easily updated on the existing candidate road instead of the new candidate road. That is, erroneous correction of the vehicle position on a road (new candidate road) different from the existing candidate road where the vehicle is actually located can be prevented as much as possible.

  Note that the reference distance is larger than the existing candidate road GPS distance difference assumed when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is. However, the reference distance is larger than the existing candidate road GPS distance difference assumed when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is. A value that is smaller than the existing candidate road GPS distance difference that is assumed when the vehicle enters the new candidate road at a branch point on the existing candidate road and travels on the new candidate road Is preferred. This is to prevent the vehicle position from being erroneously updated on the existing candidate road when it should be updated on the new candidate road.

  The reference distance is a value larger than the existing candidate road GPS distance difference assumed when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels as it is, In addition, the operation when the vehicle is set to a value smaller than the existing candidate road GPS distance difference assumed when the vehicle enters the new candidate road at the branch point on the existing candidate road and travels on the new candidate road is illustrated. This will be described with reference to 4 (b). As shown in FIG. 4 (b), the vehicle traveling on the point P0 on the road R1 at the time T0 moves to the point P1 ′ on the road R2 at the time T1, and the position measured by the GPS at the time T1 of the vehicle is When the Q1 ′ point is outside the road, the reference distance determination unit 220 determines the difference between the existing candidate road GPS distances of the existing candidate road (road R1) (the difference “Y” between the previous GPS distance D1 and the current GPS distance D4). Is not less than the reference distance X (step S150: No). The existing candidate road GPS distance difference Y is substantially equal to the distance D9 between the existing candidate road (road R1) and the new candidate road (road R2).

  In this case, the evaluation value calculation unit 230 calculates the evaluation value relating to the existing candidate road (road R1) by substituting the GPS distance D4 of the existing candidate road (road R1) into the evaluation formula (step S162). The evaluation value calculation unit 230 calculates the evaluation value related to the new candidate road (road R2) by substituting the GPS distance D5 of the new candidate road (road R2) into the evaluation formula (step S170). Thereby, the vehicle position update part 240 updates a vehicle position on the new candidate road (road R2) which is the highest evaluation value (step S180). That is, the vehicle position is correctly corrected from the point Q1 'to the actual point P1' on the road R2 (not corrected to the point P1 on the road R1).

  The reference distance may be a constant value or a variable value. When the reference distance is a constant value, the processing load can be reduced compared to when the reference distance is a variable value. If the reference distance is a variable value, the candidate road can be detected using conditions appropriate for the situation. Various methods for setting the reference distance to a variable value are conceivable. For example, in FIG. 4B, the reference distance X is set to the distance D9 (that is, the existing candidate road (road R1) and the new candidate road (road R2)). There is a method of setting a variable value according to the GPS distance D4 of the existing candidate road (road R1) and the GPS distance D5 of the new candidate road (road R2). For example, a value obtained by multiplying the distance difference D9 by a coefficient 0.5 may be used as the reference distance X. The reference distance X obtained by multiplying the distance difference D9 by a factor of 0.5 is suitable as a threshold value for determining whether the vehicle is actually traveling on an existing candidate road or a new candidate road. Because. Note that the larger the coefficient, the higher the probability that the existing candidate road GPS distance difference will be equal to or less than the reference distance, and thus the vehicle position is more likely to be updated on the existing candidate road.

  Further, in the above embodiment, when a new candidate road is detected in addition to the existing candidate road at a certain reference timing, an error in the vehicle position on a road (new candidate road) different from the existing candidate road where the vehicle is actually located. A process to prevent correction as much as possible (hereinafter referred to as “error correction prevention process”) is executed, but in addition to the existing candidate roads, it continues (similarly) at the reference timing after the reference timing at which the new candidate roads are detected (similarly), Prevention processing may be performed. FIG. 5 is a diagram for explaining how the vehicle position is updated according to the present embodiment. The operation in the case where the erroneous correction prevention processing is continuously executed at the reference timing after the reference timing at which the new candidate road is detected in addition to the existing candidate road will be described with reference to FIG.

  For example, as shown in FIG. 5 (a), a vehicle traveling on point P0 on road R1 at time T0 moves to point P1 on road R1 at time T1, and the position measured by the GPS at time T1 of the vehicle. Is the Q1 point outside the road, the GPS distance calculation unit 210 first stores information indicating that the erroneous correction prevention processing should be continued (hereinafter referred to as “error correction prevention processing continuation information”) in the RAM 26. It is judged that it is not memorized. The GPS distance calculation unit 210 that has determined that the erroneous correction prevention process continuation information is not stored in the RAM 26 further indicates that the candidate road detection unit 200 detects a new candidate road (road R2) in addition to the existing candidate road (road R1). The reference distance determination notification is supplied to the reference distance determination unit 220.

  The reference distance determination unit 220 that has acquired the reference distance determination notification from the GPS distance calculation unit 210 determines that the existing candidate road GPS distance difference between the existing candidate road (road R1) (the difference between the previous GPS distance D1 and the current GPS distance D1 is “0”. ”) And the calculated existing candidate road GPS distance difference“ 0 ”is determined to be less than or equal to the reference distance X. The reference distance determination unit 220 supplies the existing candidate road GPS distance difference “0” of the existing candidate road (road R1) to the evaluation value calculation unit 230 together with the evaluation value calculation instruction notification.

  The evaluation value calculation unit 230 that has acquired the existing candidate road GPS distance difference “0” of the existing candidate road (road R1) together with the evaluation value calculation instruction notification from the reference distance determination unit 220 includes the GPS distance D1 of the existing candidate road (road R1). Instead of substituting the existing candidate road GPS distance difference “0” into the evaluation formula, the evaluation value relating to the existing candidate road (road R1) is calculated, and the GPS distance D2 of the new candidate road (road R2) is substituted into the evaluation formula. An evaluation value relating to a new candidate road (road R2) is calculated. The evaluation value calculation unit 230 supplies the existing candidate road (road R1) having the highest evaluation value to the vehicle position update unit 240 and corrects the error in association with the existing candidate road (road R1) having the highest evaluation value. The prevention process continuation information is stored in the RAM 26. The vehicle position is correctly corrected from the point Q1 to the actual point P1 on the road R1 (not corrected to the point P1 'on the road R2).

  Further, when the vehicle traveling on the point P1 on the road R1 at the time T1 moves to the point P2 on the road R1 at the time T2, and the GPS measurement position at the time T2 of the vehicle becomes the point Q2 outside the road. When the GPS distance calculation unit 210 determines that the erroneous correction prevention process continuation information is stored in the RAM 26 in association with the existing candidate road (road R1), the candidate road detection unit 200 uses the existing candidate roads (road R1 and road R2). In addition, the reference distance determination notification is supplied to the reference distance determination unit 220 without determining whether a new candidate road has been detected (or regardless of the determination result). At time T1, road R2 is an existing candidate road.

  The reference distance determination unit 220 that has acquired the reference distance determination notification from the GPS distance calculation unit 210 has the existing candidate road GPS distance difference of the existing candidate road (road R1) stored in the RAM 26 in association with the erroneous correction prevention process continuation information. (A difference “0” between the previous GPS distance D1 and the current GPS distance D1) is calculated, and it is determined that the calculated existing candidate road GPS distance difference “0” is equal to or less than the reference distance X. The reference distance determination unit 220 supplies the existing candidate road GPS distance difference “0” of the existing candidate road (road R1) to the evaluation value calculation unit 230 together with the evaluation value calculation instruction notification.

  The evaluation value calculation unit 230 that has acquired the existing candidate road GPS distance difference “0” of the existing candidate road (road R1) together with the evaluation value calculation instruction notification from the reference distance determination unit 220 includes the GPS distance D1 of the existing candidate road (road R1). Instead of substituting the existing candidate road GPS distance difference “0” into the evaluation formula, the evaluation value relating to the existing candidate road (road R1) is calculated, and the GPS distance D2 of the existing candidate road (road R2) is substituted into the evaluation formula. An evaluation value related to the existing candidate road (road R2) is calculated. The evaluation value calculation unit 230 supplies the existing candidate road (road R1) having the highest evaluation value to the vehicle position update unit 240 and corrects the error in association with the existing candidate road (road R1) having the highest evaluation value. The prevention process continuation information is stored in the RAM 26 (not erased). The vehicle position is correctly corrected from the point Q2 to the actual point P2 on the road R1 (not corrected to the point P2 'on the road R2).

  That is, the evaluation value calculation unit 230 replaces the GPS distance D1 of the existing candidate road (road R1) with the previous candidate (time T1), instead of the existing candidate road GPS distance difference “0” (before the existing candidate road (time T0). The evaluation value calculated by substituting the GPS distance D1 of the current candidate road and the previous (time T1) GPS distance D1 related to the existing candidate road into the evaluation formula is the highest, and the reference distance determination unit 220 Is determined that the difference between the previous (time T1) GPS distance D1 related to the existing candidate road (road R1) and the current (time T2) GPS distance D1 related to the existing candidate road (road R1) is equal to or less than the reference distance X. In this case, the previous time (time T1) related to the highest evaluation existing candidate road (road R1) instead of the current GPS distance D1 (time T2) related to the highest evaluation existing candidate road (road R1) having the highest evaluation value. GP of Distance by substituting a difference in evaluation formula of D1 and the highest rating existing road candidates GPS distance D1 of the current according to (road R1) (time T2) for calculating the maximum evaluation evaluation value according to the existing candidate roads (road R1). Thus, when the vehicle does not enter the new candidate road at the branch point on the existing candidate road and travels on the existing candidate road as it is, a road that is different from the existing candidate road where the vehicle is actually located (new candidate road) In addition to preventing erroneous correction of the upward vehicle position as much as possible, even when the vehicle further travels on the existing candidate road, the vehicle position on the road different from the existing candidate road where the vehicle is actually located is continued. It becomes possible to prevent erroneous correction as much as possible.

  In the above embodiment, an example in which there is one existing candidate road has been described, but there may naturally be a plurality of existing candidate roads. Further, when there are a plurality of candidate roads having the highest evaluation value, the vehicle position is updated on any candidate road having the highest evaluation value. As an example, the vehicle position is updated on the candidate road with the smallest GPS distance.

  For example, as shown in FIG. 5 (b), a vehicle traveling on point P0 on road R1 at time T0 moves to point P1 on road R1 at time T1, and the position measured by the GPS at time T1 of the vehicle. Is Q1 outside the road, the existing candidate road GPS distance difference “0” of the existing candidate road (road R0) parallel to the existing candidate road (road R1) and the existing candidate road of the existing candidate road (road R1) There are two candidate roads that match the GPS distance difference “0” and have the highest evaluation value: the existing candidate road (road R0) and the existing candidate road (road R1), but the vehicle position is the road from point Q1. Correctly corrected to actual P1 point on R1 (not corrected to P1 ′ point on road R2 and P1 ″ point on road R0).

  In addition, when the position measured by the GPS at time T0 of the vehicle was at point Q0 outside the road, a new candidate road (road R2) was not detected in addition to the existing candidate roads (road R0 and road R1). The difference between the existing candidate road GPS distances of the candidate roads (road R0 and road R1) is not calculated. In this case, since the GPS distance D1 of the existing candidate road (road R1) is smaller than the GPS distance D0 of the existing candidate road (road R0), the vehicle position is correctly corrected from the point Q0 to the actual point P0 on the road R1. (It is not corrected to the point P0 ″ on the road R0).

  Moreover, in the said embodiment, although the GPS distance (Including the case where an existing candidate road GPS distance difference is substituted instead of GPS distance) is substituted into an evaluation formula, the example which calculates an evaluation value is demonstrated, The evaluation value may be calculated by substituting other variables into the evaluation formula in addition to the GPS distance. For example, in addition to the GPS distance, the estimated vehicle position and vehicle orientation data (hereinafter referred to as “autonomous navigation position”) obtained by the autonomous navigation sensor measured by the position measurement unit 23 and the distance between the candidate roads (hereinafter referred to as “autonomous navigation”). Distance ”), the angle difference between the straight line indicated by the history of GPS position (or autonomous navigation position) and the candidate road (hereinafter referred to as“ candidate road angle difference ”), the connection between the road where the vehicle position exists and the candidate road One or more of the characteristics (whether the road where the vehicle position exists and the candidate road are directly connected, or the number of roads interposed between the road where the vehicle position exists and the candidate road), etc. The evaluation value is calculated by substituting it into the evaluation formula as a variable.

  For example, when the evaluation value is calculated by substituting the autonomous navigation distance in the evaluation formula in addition to the GPS position, the candidate road detection unit 200 determines the autonomous navigation position from the position measurement unit 23 in addition to the GPS position at each reference timing. get. The candidate road detection unit 200 refers to the GPS position, the autonomous navigation position, and the map data stored in the map information memory 22 to detect a candidate road. The candidate road detection unit 200 stores the GPS position, the autonomous navigation position, and the candidate road in the RAM 26 and supplies a GPS distance calculation notification to the GPS distance calculation unit 210.

  When only the evaluation value calculation instruction notification is acquired from the GPS distance calculation unit 210, the evaluation value calculation unit 230 substitutes the current GPS distance and the autonomous navigation position related to the existing candidate road stored in the RAM 26 into the evaluation formula, and An evaluation value related to the road is calculated. When only the evaluation value calculation instruction notification is acquired from the reference distance determination unit 220, the evaluation value calculation unit 230 substitutes the current GPS distance and the autonomous navigation position related to the existing candidate road stored in the RAM 26 into the evaluation formula. The evaluation value related to the road is calculated, and the current GPS distance and the autonomous navigation position related to the new candidate road stored in the RAM 26 are substituted into the evaluation formula to calculate the evaluation value related to the new candidate road.

  On the other hand, when the evaluation value calculation unit 230 acquires the existing candidate road GPS distance difference from the reference distance determination unit 220 together with the evaluation value calculation instruction notification, the evaluation value calculation unit 230 stores the existing candidate road GPS distance difference acquired from the reference distance determination unit 220 and the RAM 26. The evaluation value related to the existing candidate road is calculated by substituting the autonomous navigation position stored in the evaluation formula, and the current GPS distance and the autonomous navigation position related to the new candidate road stored in the RAM 26 are substituted into the evaluation formula. An evaluation value related to the candidate road is calculated. Of the GPS distance, autonomous navigation distance, candidate road angle difference, and connectivity, the variable that most affects the evaluation value is the GPS distance. Therefore, if the existing candidate road GPS distance difference is substituted in place of the GPS distance, the evaluation value increases without being influenced so much by the autonomous navigation distance (the candidate road angle difference and connectivity are the same).

  Note that the operations of the GPS distance calculation unit 210, the reference distance determination unit 220, and the vehicle position update unit 240 when calculating the evaluation value by substituting the autonomous navigation distance in the evaluation formula in addition to the GPS position evaluate only the GPS position. This is the same as the case where the evaluation value is calculated by substituting it into the equation.

  In addition, when the evaluation value is calculated by substituting the candidate road angle difference in addition to the GPS position into the evaluation formula, the candidate road detection unit 200 acquires the GPS position acquired from the position measurement unit 23 and the past stored in the RAM 26. The candidate road angle difference of the detected candidate road is calculated with reference to the GPS position and the map data stored in the map information memory 22, and the calculated candidate road angle difference is stored in the RAM 26 in association with the candidate road. In addition, when the evaluation value is calculated by substituting connectivity in addition to the GPS position into the evaluation formula, the candidate road detection unit 200 is stored in the previous vehicle position stored in the RAM 26 and the map information memory 22. The connectivity of the detected candidate road is calculated with reference to the map data, and the calculated connectivity is stored in the RAM 26 in association with the candidate road. A GPS distance calculation unit 210, a reference distance determination unit 220, an evaluation value calculation unit 230, and a vehicle position update unit when calculating an evaluation value by substituting a candidate road angle difference or connectivity into the evaluation formula in addition to the GPS position The operation 240 is the same as the operation in the case where the evaluation value is calculated by substituting the autonomous navigation distance into the evaluation formula in addition to the GPS position.

  In addition, each of the above-described embodiments is merely an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

It is a figure which shows the structural example of the navigation apparatus which is embodiment of this invention. It is a figure for demonstrating the candidate road detection part of this embodiment, a GPS distance calculation part, a reference distance determination part, an evaluation value calculation part, and a vehicle position update part. It is a flowchart which shows the operation example of the navigation apparatus shown in FIG. It is a figure for demonstrating a mode that a vehicle position is updated by this embodiment. It is a figure for demonstrating a mode that a vehicle position is updated by this embodiment. It is a figure for demonstrating a mode that a vehicle position is updated by the conventional projection method.

Explanation of symbols

4 DVD-ROM
DESCRIPTION OF SYMBOLS 10 Navigation apparatus 22 Map information memory 23 Position measurement part 24 CPU
25 ROM
26 RAM
33 Mark generator 200 Candidate road detector 210 GPS distance calculator 220 Reference distance determiner 230 Evaluation value calculator 230 Vehicle position updater

Claims (3)

A navigation device for drawing a map on a display screen based on map data including road information and displaying a vehicle position mark indicating a vehicle position on the map,
A candidate road detection unit that detects each time a candidate road that is a candidate for updating the vehicle position based on the measurement position of the vehicle measured each time;
A GPS distance calculation unit that calculates a distance between a GPS position, which is a measurement position of a vehicle measured each time using GPS, and the candidate road detected each time by the candidate road detection unit as a GPS distance related to the candidate road; ,
When the candidate road detection unit detects a previous undetected new candidate road in addition to the previous detected existing candidate road this time, the previous GPS distance and the GPS related to the existing candidate road calculated by the GPS distance calculation unit last time A reference distance determination unit that determines whether a difference from the current GPS distance related to the existing candidate road calculated by the distance calculation unit is equal to or less than a reference distance;
When the candidate road detection unit detects a new candidate road that has not been detected last time in addition to the existing candidate road that has been detected last time, and the reference distance determination unit determines the previous GPS distance related to the existing candidate road and the above Evaluation that calculates a higher evaluation value as the GPS distance is shorter when it is determined that the difference from the current GPS distance related to the existing candidate road is not equal to or less than the reference distance as a variable. Substituting the current GPS distance for the existing candidate road into the formula to calculate the evaluation value for the existing candidate road, and the current time for the new candidate road calculated by the GPS distance calculation unit for the evaluation formula While calculating the evaluation value relating to the new candidate road by substituting the GPS distance of the new candidate road, the candidate road detecting unit adds to the existing candidate road detected last time and the previously undetected new candidate road In this case, the reference distance determination unit determines that the difference between the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road is equal to or less than the reference distance. In this case, instead of the current GPS distance related to the existing candidate road, the difference between the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road is substituted into the evaluation formula. An evaluation value calculating unit that calculates the evaluation value related to the existing candidate road, calculates the evaluation value related to the new candidate road by substituting the current GPS distance related to the new candidate road into the evaluation formula;
A navigation apparatus comprising: a vehicle position update unit that updates the vehicle position on the candidate road having the highest evaluation value calculated by the evaluation value calculation unit. The evaluation value calculation unit further calculates a difference between the previous GPS distance related to the existing candidate road and the previous GPS distance related to the existing candidate road instead of the previous GPS distance related to the existing candidate road from the evaluation formula The evaluation value calculated by substituting for is higher than the evaluation value calculated by substituting the current GPS distance for another existing candidate road into the evaluation formula , and the reference distance determination Department determines that the difference between the previous GPS distance related to the existing candidate road and the current GPS distance related to the existing candidate road is less than or equal to the reference distance, the one with the higher previous evaluation value the difference between the current GPS distance according to the existing candidate best rated existing candidates according to the road this time instead of the GPS distance last according to the highest rating existing road candidates GPS distance and the highest rating existing candidate roads is road The navigation device according to claim 1, by substituting the serial evaluation formula and calculates the current of the evaluation value according to the maximum evaluation existing road candidates. A measurement step for measuring the position of the vehicle each time;
Candidate road detection step for detecting each time a candidate road that is a candidate for updating the vehicle position based on the measurement position of the vehicle measured each time by the measurement step;
A GPS distance calculation step for calculating the distance between the GPS position, which is a vehicle measurement position measured each time using GPS, and the candidate road detected each time by the candidate road detection step as a GPS distance related to the candidate road; ,
When the existing candidate road detected last time by the candidate road detection step is also detected this time, the previous GPS distance related to the existing candidate road previously calculated by the GPS distance calculation step and the current GPS distance calculation step A reference distance determination step for determining whether or not a difference between the calculated GPS distance relating to the existing candidate road is equal to or less than a reference distance;
In addition to the previously detected existing candidate road, a previously undetected new candidate road is detected this time by the candidate road detecting step, and the previous GPS distance related to the existing candidate road and the existing candidate road When it is determined in the reference distance determination step that the difference from the current GPS distance is not less than or equal to the reference distance, an equation including the GPS distance as a variable is calculated. The shorter the GPS distance is, the higher the evaluation value is calculated. Substituting the current GPS distance related to the existing candidate road for the evaluation formula to calculate the evaluation value related to the existing candidate road, and the new candidate road calculated this time by the GPS distance calculation step to the evaluation formula A first evaluation value calculating step of calculating the evaluation value related to the new candidate road by substituting the current GPS distance related to
In addition to the previously detected existing candidate road, a previously undetected new candidate road is detected this time by the candidate road detecting step, and the previous GPS distance related to the existing candidate road and the existing candidate road When the reference distance determination step determines that the difference from the current GPS distance is equal to or less than the reference distance, the evaluation formula relates to the existing candidate road instead of the current GPS distance related to the existing candidate road. The difference between the previous GPS distance and the current GPS distance related to the existing candidate road is substituted to calculate the evaluation value related to the existing candidate road, and the current GPS distance related to the new candidate road in the evaluation formula A second evaluation value calculating step for calculating the evaluation value related to the new candidate road by substituting
A vehicle position update method comprising: a vehicle position update step of updating the vehicle position on the candidate road having the highest evaluation value calculated by the first evaluation value calculation step or the second evaluation value calculation step.