JP2008101986A - On-vehicle device, and travel distance correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of correcting an error in a travel distance, without travel of a certain extent of distance. <P>SOLUTION: A rotation speed of a wheel is acquired during travel between dotted lines drawn on a road face in an expressway, or a rotation speed of an axle is acquired during travel between kilometer posts in the expressway, based on an image data photographed by a camera, and the travel distance of the vehicle is corrected based on the acquired rotation speed of the wheel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle device that calculates a travel distance.

  Conventionally, an in-vehicle device mounted on a vehicle calculates a current position based on a traveling direction of a vehicle measured by an orientation sensor such as a gyro and a traveling distance of the vehicle measured by a vehicle speed sensor or a distance sensor. Things have been done.

  The vehicle travel distance is generally measured by measuring the output shaft of the transmission or the rotation speed of the tire, and multiplying the rotation speed by the distance coefficient that is the distance the vehicle travels per rotation of the tire. It is demanded by.

  By the way, during running, the tire diameter, that is, the distance coefficient changes every moment due to tire wear, expansion due to temperature change, and the like. For this reason, an error occurs in the calculation of the travel distance, and the current position cannot be calculated with high accuracy. For example, if there is an error of 1% in the travel distance coefficient per one rotation of the tire, an error of 1 km occurs when the vehicle travels 100 km.

  Such a measurement error of the travel distance can be corrected to some extent by a conventional map matching technique when traveling on a normal road. However, when driving on a road such as an expressway, the road does not have characteristics such as curves and intersections used for correcting the travel distance, so that the error cannot be corrected sufficiently.

  Even if the vehicle does not travel on a highway or the like, once an error of about 1 km occurs between the measured current position and the true current position, the map matching technique can correct it to the correct position. It can be difficult.

  As a technique for eliminating such a measurement error of travel distance, there is a technique described in Patent Document 1. Patent Document 1 describes a technique for obtaining a cumulative value of a road vehicle heading difference, further obtaining error information corresponding to an error of the distance coefficient, and correcting the distance coefficient based on the error information.

JP 2008-334360 A

  The technique described in Patent Literature 1 acquires an error in travel distance from the accumulated value of the road vehicle heading difference. Therefore, in order to correct the error, it is necessary for the vehicle to travel a certain distance, and quick error correction cannot be performed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique capable of correcting an error in travel distance without traveling a certain distance.

  The present invention has been made to achieve the above object, and is characterized in that the travel distance of the vehicle is corrected from the rotational speed of the axle while traveling between those having a clear distance.

  Further, the present invention is an in-vehicle device mounted on a vehicle that moves with the rotation of a wheel, wherein a camera that captures a road surface of a road on which the vehicle travels, and the number of rotations of a wheel for a predetermined time are set. Travel distance calculating means for calculating the travel distance of the vehicle according to the distance coefficient, and when the vehicle is traveling on the expressway, from the image data acquired by the camera, on the expressway It acquires the rotational speed of the wheel while traveling at least one of the white line part and the blank part of the dotted line drawn on the road surface, and corrects the traveling distance of the vehicle from the acquired rotational speed of the wheel. .

  According to the technology of the present invention, it is possible to correct the travel distance of a vehicle from the rotational speed of an axle while traveling between dotted lines drawn on a road surface on an expressway or between kiloposts. The distance between the dotted lines drawn on the road surface on the expressway on the expressway and the distance between the kilometer posts are constant, and it exists in almost all sections on the expressway, so it does not travel a certain distance In addition, it becomes possible to correct the error of the travel distance.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In the embodiment described below, the travel distance of the vehicle is corrected from the number of rotations of the axle while traveling between the distances that are clear. This clear distance is not particularly limited, but here, an example will be described where the distance is between dotted lines on a road surface on a highway, a distance post, or the like.
<First Embodiment>
First, an embodiment will be described in which the travel distance of a vehicle is corrected from the rotational speed of an axle while traveling between dotted lines drawn on a road surface on an expressway. The “dotted line” referred to here is a dotted line drawn on the road surface to show a lane on the expressway. This dotted line indicates a lane that can be overtaken. On the expressway, among the dotted lines, the white line portion is drawn at 8 m, and the blank portion following the white line portion is drawn at 12 m, and this distance is constant everywhere.

  With reference to FIG. 1, the structural example of the navigation system 1 of this embodiment is demonstrated. The navigation system 1 is mounted on a vehicle (not shown). 1, a navigation system 1 includes an angular velocity sensor 101, a vehicle speed sensor 102, a calculation unit 103, a GPS (Global Positioning System) receiver 104, a storage device 105, an input device 106, a display 107, an audio output device 108, and a communication interface 109. A camera 110 and the like.

  The angular velocity sensor 101 detects a change in the direction of the vehicle on which the navigation system 1 is mounted by detecting the yaw rate of the vehicle. The vehicle speed sensor 102 calculates the vehicle speed by counting pulses output at time intervals proportional to the rotation of the output shaft of the vehicle transmission.

  The GPS receiver 104 is equipped with the navigation system 1 by receiving a signal from a GPS satellite and measuring the distance between the vehicle on which the navigation system 1 is installed and the GPS satellite and the rate of change of the distance. Measure vehicle position, heading direction, speed, etc.

  The storage device 105 is, for example, a storage medium such as a CD-R (Compact Disc-Recordable) or a DVD-RAM (Digital Versatile Disk-Random Access Memory), a drive device for the storage medium, an HDD (Hard Disk Drive), or the like. Stores map data and the like.

  The input device 106 is, for example, a remote control and a remote control receiving unit, a touch panel, a switch, or the like.

  The display 107 displays a map, and synthesizes and displays the current position, route, and the like on the displayed map. The voice output device 108 is, for example, a speaker and outputs a voice for guidance and the like.

  The camera 110 is, for example, a camera that captures the front of the vehicle or a camera that captures the rear of the vehicle. This camera 110 may be provided for travel distance correction described below, or may be provided for other functions such as for lane keeping and for back view monitoring. Here, description will be made assuming that the camera 110 is for the back view monitor.

  The arithmetic unit 103 is for controlling the operation of each peripheral device described above, and includes an AD converter 121, a counter 122, a RAM 123, a ROM (Read Only Memory) 124, a CPU (Central Processing Unit) 125, and the like. .

  The AD converter 121 converts the signal (analog) of the angular velocity sensor 101 into a digital signal. The counter 122 counts the number of pulses output from the vehicle speed sensor 102, for example, every 0.1 second. The RAM 123 stores calculation data by the CPU 125, data read from the storage device 105, and the like. The ROM 124 stores programs, data, and the like.

  The CPU 125 implements a current position calculation unit 141, an activation determination unit 142, a camera control unit 143, a rotation speed acquisition unit 144, a correction unit 145, and the like by executing a program (not shown) in the ROM 124. The current position calculation unit 141 calculates the current position of the vehicle on which the navigation system 1 is mounted. The current position calculation process of the current position calculation unit 141 is the same as that of the conventional technique. The activation determination unit 142 determines whether or not to perform subsequent processing depending on whether or not the current position of the vehicle is on the expressway. The camera control unit 143 controls shooting by the camera 110. The rotation speed acquisition unit 144 performs image processing on the image data captured by the camera 110 to detect a dotted line on the expressway, and includes a certain white line part and a blank part following the white line part among the dotted lines on the expressway. Get the number of pulses while passing. The technique in which the rotation speed acquisition unit 144 detects a dotted line by image processing is the same as the conventional technique. The correction unit 145 corrects the moving distance of the vehicle from the number of pulses acquired by the rotation speed acquisition unit 144.

  Although not shown, the navigation system 1 executes a program read out from the ROM 124 by the CPU 125, thereby searching for a route search function by a Dijkstra method, a recommended route guidance function, an address, a telephone number, a place name, a landmark, and the like. It may have functions such as functions that the navigation system of the prior art has. Here, the search function indicates, for example, the address data indicating the address and the location of the address, the phone book data indicating the location of the phone number and the phone number, and the location name and the location of the location name in advance in the storage device 105. Stores place name data, names of major buildings and places, and detailed information and landmark data that indicates the location, etc., and the search function applies from the input address, telephone number, place name, landmark, etc. The position and detailed information to be searched are displayed and displayed.

  Next, map data and the like stored in the storage device 105 will be described.

  In the present embodiment, the map data includes a plurality of meshes uniquely determined by latitude and longitude, and XY coordinates indicating positions in each mesh. Each mesh is indicated by a mesh ID. The map data includes a mesh ID, image data of a plurality of maps including XY coordinates in the mesh ID, road data, address data, place name data, and the like. The position on the map data is uniquely indicated by the mesh ID and XY coordinates.

  The road data is approximated by one or more line segments connecting two points, and these line segments are indicated by XY coordinates of the start point and the end point. Hereinafter, this line segment is called a link, and points at both ends of the link are called nodes.

  FIG. 2 is an example of map data stored in the storage device 105. In FIG. 2, the map data has a plurality of map information tables 201. The map information table 201 includes one mesh ID 202, one or more link information 203, and the like. The mesh ID 202, the link information 203, and the like are associated with each other. The mesh ID 202 is a mesh identification code. The link information 203 is information related to each link constituting the road included in the mesh with the corresponding mesh ID 202.

  The link information 203 includes a link ID 211, start node coordinates 212, end node coordinates 213, road type 214, link length information 215, regulated speed information 216, start connection link 217, end connection link 218, and the like. Link ID 211, start node coordinates 212, end node coordinates 213, road type 214, link length information 215, regulated speed information 216, start connection link 217, end connection link 218, and the like are associated with each other. The link ID 211 is a link identification code. The start node coordinates 212 and the end node coordinates 213 are the latitude and longitude of two nodes (start node and end node) constituting the link with the corresponding link ID 211. The road type 214 is a type of road including the link with the corresponding link ID 211. In the example of FIG. 2, the road type 214 includes “general road”, “highway”, and the like. The link length information 215 indicates the link length of the corresponding link ID 211. The restriction speed information 216 indicates the restriction speed (limit speed) of the link with the corresponding link ID 211. The start connection link 217 and the end connection link 218 are link IDs of links to which two nodes of the corresponding link ID 211 link are respectively connected. Here, by distinguishing the start node and the end node for the two nodes constituting the link, the upward direction and the downward direction of the same road are managed as different links. Although not shown, the map information table 201 includes information on map components other than roads (address, telephone number, name, XY coordinates, etc.) included in the mesh indicated by the mesh ID 202, and map images. Information etc. may also be included.

  2 is stored in advance in the storage device 105 of the navigation system 1.

  Next, an operation example will be described.

  First, an operation example for calculating the current position will be described.

  The operation illustrated in FIG. 3 is an operation performed by the current position calculation unit 141 at a constant cycle, for example, every 100 mS.

  First, the current position calculation unit 141 reads the output value of the angular velocity sensor 101 from the AD converter 121 (S301). Next, the current position calculation unit 141 calculates the traveling direction of the vehicle from the output value of the angular velocity sensor 101 (S302).

  The current position calculation unit 141 counts the number of pulses output from the vehicle speed sensor 102 by the counter 122 every predetermined time such as every 0.1 second, and reads the count value (S303). The current position calculation unit 141 calculates a distance traveled during a predetermined time of 0.1 seconds by multiplying the read value by a distance coefficient (S304). Specifically, for example, when the measured value by the counter 122 is “Cp” and the distance coefficient is “R”, the distance “lu” that has advanced for 0.1 seconds is expressed by the following equation.

lu = Cp × R
The current position calculation unit 141 sequentially stores the travel direction and distance for each predetermined time acquired in this manner in the RAM 123.

  Next, the current position calculation unit 141 adds the distance value traveled by the vehicle on which the navigation system 1 is mounted within the predetermined time calculated in S304 to the distance value until the previous time, and the added distance is predetermined. It is determined whether or not the distance (for example, 20 m) is exceeded (S305).

  If the result of determination in S305 is that the distance is less than the predetermined distance, the current position calculation unit 141 ends the current process, and performs the above process again after a certain period.

  If the result of determination in S305 is that the distance is equal to or greater than the predetermined distance, the current position calculation unit 141 stores the traveling direction and distance at that time in the RAM 123, and executes map matching processing described later (S306). The distance stored in the RAM 123 by the current position calculation unit 141 is the predetermined distance used for the determination in the process of S305, and is 20 m, for example.

  Next, an example of map match operation will be described with reference to FIG.

  First, the current position calculation unit 141 reads the traveling direction, distance, and the like from the RAM 123 (S401). Next, the current position calculation unit 141 calculates the movement amount of the vehicle on which the navigation system 1 is mounted separately for the latitude direction and the longitude direction based on the read traveling direction and distance. Furthermore, the current position calculation unit 141 adds the calculated movement amount in each direction to the position of the candidate point obtained in the previous map match process, and is the virtual current position that is currently estimated to be present. The position is calculated (S402).

  Next, the current position calculation unit 141 calculates one or more candidate points from the calculated virtual current position and the road data included in the map data (S403), and further calculates the reliability of each candidate point. (S404).

  Here, candidate points and reliability will be described. The current position calculation unit 141 reads a map around the virtual current position from the storage device 105, selects road data (line segments) within a preset distance D centered on the virtual current position, and selects these Take out. In the present embodiment, a map included in an area corresponding to a square having a length L1 centered on the virtual current position is read from the storage device 105.

  Next, the current position calculation unit 141 selects and selects only the line segment in which the direction of the line segment is within the predetermined value from the extracted direction from the extracted line segment. With respect to all the n line segments, a perpendicular line is dropped from the virtual current position, and the length of the perpendicular line L (n) is obtained. Next, based on the lengths of these perpendicular lines, an error cost value ec (n) defined by the following equation is calculated for each selected line segment.

ec (n) = α × | θcar−θ (n) | + β | L (n) |
Here, θcar is the vehicle direction at the virtual current position, θ (n) is the direction of the line segment, L (n) is the distance from the virtual current position to the line segment, that is, the length of the perpendicular, α and β are , A weighting factor. The values of these weighting factors may be changed depending on whether the shift in the traveling direction or the direction of the road or the shift in the current position or the road is important in selecting a road on which the current position is located.

  Next, the current position calculation unit 141 is defined by the following equation according to the calculated error cost ec (n) and the accumulated error cost es related to the candidate point calculated in the previous process. The accumulated error cost es (n) in the current process is calculated.

es (n) = (1-k) × es + k × ec (n)
Here, k is a weight coefficient larger than 0 and smaller than 1. Next, the current position calculation unit 141 calculates a reliability trst (n) defined by the following equation based on the calculated accumulated error cost es (n).

trst (n) = 100 / (1 + es (n))
Next, based on the calculated reliability trst (n), the current position calculation unit 141 sets a point advanced from a certain candidate point by a length corresponding to the distance R traveled by the vehicle along the corresponding line segment. And a new candidate point C (n). Therefore, when the number of line segments that are within a predetermined range D from the current position A with respect to a candidate point and the difference between the direction and the vehicle direction is equal to or less than a predetermined value is n, n pieces A new candidate point C (n) will be generated.

  When the candidate point and the reliability of each candidate point are calculated, the current position calculation unit 141 selects a candidate point having the highest reliability value among the candidate points, and sets the candidate point as a display candidate point ( S405). This display candidate point becomes information indicating the current position displayed on the display 107. The current position calculation unit 141 stores information indicating the position of the display candidate point in the RAM 123.

  Next, the current position calculation unit 141 positions the display candidate points read from the predetermined area of the RAM 123 on the map and displays them on the display 107 (S406).

  The current position may be calculated from the traveling direction, distance, map data, etc. acquired by the sensor as described above, or from the position, traveling direction, traveling direction, etc. received by the GPS receiver 104. May be. In addition, the current position calculated from the traveling direction, distance, map data, and the like acquired by the above-described sensor may be corrected by the position received by the GPS receiver 104. Such calculation processing of the current position is the same as that of the conventional navigation system.

  Next, an operation example for correcting the travel distance of the vehicle will be described with reference to FIG.

  The operation example described below is activated, for example, every predetermined time and every predetermined distance.

  When activated, the activation determination unit 142 determines whether the current position of the vehicle is on the highway (S501). For this purpose, the activation determination unit 142 selects, for example, the link information 203 including the link ID 211 of the link where the display candidate point calculated by the above-described processing exists from the map information table 201, and is included in the selected link information 203. It is determined whether or not the road type 214 is “highway”.

  As a result of the determination in S501, if the current position of the vehicle is not on the highway, the activation determination unit 142 ends the process.

  As a result of the determination in S501, if the current position of the vehicle is on the highway, the activation determination unit 142 instructs the camera control unit 143 to activate the camera 110. In accordance with the instruction, the camera control unit 143 outputs a predetermined command and instructs the camera 110 to start photographing. The camera 110 starts shooting (S502).

  The camera 110 inputs the captured image to the navigation system 1.

  The rotation speed acquisition unit 144 performs image processing on the input image and determines whether a dotted white line part and a blank part are detected (S503). This image processing is the same as the prior art, and a specific method is arbitrary. For example, a dotted line drawn on the road surface may be detected by pattern matching. A specific operation example will be described later. Note that the rotation speed acquisition unit 144 determines whether the white line portion and the blank portion are detected depending on whether the white line portion and the blank portion are detected within a predetermined time after the start of shooting by the camera 110 in S502. You may judge.

  As a result of the determination in S503, when the white line portion and the blank portion are not detected, the rotation speed acquisition unit 144 performs the process of S506 described later.

  When the white line portion and the blank portion are detected as a result of the determination in S503, the rotation speed acquisition unit 144 acquires the number of pulses while traveling from one blank portion to the next blank portion (S504). Although this specific processing is not particularly limited, for example, the white line portion existing at a predetermined position on a certain image disappears at the same position of the subsequent image, and further, the white line portion again at the same position of the subsequent image. The pulse value by the counter 122 is acquired while the part exists.

  Here, an example of processing in which the rotation speed acquisition unit 144 detects white line portions and blank portions in S503 and S504 will be described.

  As described above, the rotation speed acquisition unit 144 detects a dotted line by performing processing such as pattern matching on each captured image. As a specific example, for example, a reference pattern having a dotted white line part and a blank part, and a reference pattern having only a white line part can be considered.

  First, an example in which the reference pattern has a dotted white line part and a blank part will be described.

  In the process of S503, the rotation speed acquisition unit 144 determines whether a white line portion and a blank portion are detected, for example, based on whether or not a portion that matches the reference pattern is included in the captured image. In the process of S504, the rotation speed acquisition unit 144 selects a first image having a white line end portion of the reference pattern at a predetermined position of each image among a plurality of images photographed continuously. Next, the rotation speed acquisition unit 144 selects a second image that is taken after the first image and has the end of the white line portion of the reference pattern at the same predetermined position as the first image. To do. The rotation speed acquisition unit 144 acquires the number of pulses counted by the counter 122 between the time when the first image is captured and the time when the second image is captured. Here, the first image and the second image are, for example, an “n” th (n ≧ 1) integer image and an “n + 1” th image. Alternatively, the “n” th image and the “n + m” th (m ≧ 1 integer) image may be used. The value of “m” may be a predetermined value, or may be changed according to the vehicle speed, such as a smaller value as the vehicle traveling speed is faster.

  Next, an example in which the reference pattern has only a dotted white line portion will be described.

  In the processing of S503, the rotation speed acquisition unit 144 first determines whether or not a white line portion has been detected based on whether or not a portion that matches the reference pattern is included in the captured image. If a white line portion is detected as a result of this determination, the rotation speed acquisition unit 144 detects a blank portion following the white line portion. Although this process is not particularly limited, the rotation speed acquisition unit 144 acquires, for example, a difference image between an image in which a white line portion is detected and an image taken after that image, and performs pattern matching or the like to It is determined whether a white line portion exists in the difference image. If the result of this determination is that there is a white line portion in the difference image, the rotational speed acquisition unit 144 determines that there is a blank portion following the white line portion. Here, the image from which the difference image is acquired may be, for example, the “n” -th image and the “n + 1” -th image as described above, or “n”. The image captured first and the image captured “n + m” may be used. The value of “m” may be a predetermined value, or may be changed according to the vehicle speed, such as a smaller value as the vehicle traveling speed is faster. In the process of S504, the rotation speed acquisition unit 144 selects a first image having a white line end portion of the reference pattern at a predetermined position of each image among a plurality of images photographed continuously. Next, the rotation speed acquisition unit 144 selects a second image that is captured after that image and has an end of the white line portion of the reference pattern at the same predetermined position as that image. The rotation speed acquisition unit 144 acquires the number of pulses counted by the counter 122 between the time when the first image is captured and the time when the second image is captured.

  Here, a specific example of acquiring the number of pulses from one blank portion to the next blank portion will be described with reference to FIG.

  FIG. 6 shows a part of an example of images taken continuously every predetermined time. In the example of FIG. 6, it is assumed that the images are taken in the order of (a), (b), (c), and (d).

  For example, in the case of the image 611 in FIG. 6A, the rotation speed acquisition unit 144 detects the presence of the white line portion 612 and the white line portion 613 at the position 601 by pattern matching or the like. As described above, when the presence of the white line portion is detected, the rotation speed acquisition unit 144 detects a blank portion following the white line portion in the next photographed image.

  In the case of the image 621 in FIG. 6B, the rotation speed acquisition unit 144 detects only the white line portion 613 at the position 601. The position 601 of the image 621 is the same position as the position 601 of the image 611. In this case, since the white line portion is not detected in the vicinity of the position of the white line portion 612 detected in the immediately preceding image 611 at the position 601 of the image 621, the rotation speed acquisition unit 144 detects the white line portion 612 detected in the previous image. It is determined that the following blank part has been detected.

  In the case of the image 631 in FIG. 6C, the rotation speed acquisition unit 144 detects only the white line portion 613 at the position 601. The position of the position 601 of the image 631 is the same position as the position 601 of the image 611 and the image 621. In this case, since the white line portion is not detected near the position of the white line portion 612 existing on the previous screen 611 at the position 601 of the image 631, the rotation speed acquisition unit 144 does nothing particularly.

  In the case of the image 641 in FIG. 6D, the rotation speed acquisition unit 144 detects the white line portion 611 and the white line portion 642 at the position 601. The position of the position 601 of the image 641 is the same position as the position 601 of the image 611 and the images 621 and 631. In this case, a blank portion following the white line portion 612 detected in the previous image 611 is detected in the subsequent image 621, and the newly detected white line 642 is the previously detected white line portion. It exists in the vicinity of the position 612. Therefore, the rotation speed acquisition unit 144 determines that the white line is continued from the blank part of the white line detected in the previous process (the process of the image 621).

  As described above, when the blank portion following the white line portion is detected, the rotation speed acquisition unit 144 takes the time when the image where the blank portion is detected is captured and the time when the image where the white line portion subsequent to the blank portion is captured is captured. In the meantime, the number of pulses counted by the counter 122 is acquired. In the example of FIG. 6, the rotation speed acquisition unit 144 acquires the number of pulses counted by the counter 122 while the image 641 is captured after the image 611 is captured.

  In FIG. 5, the correction unit 145 corrects the travel distance of the vehicle according to the number of pulses acquired in the above-described processing of S504 (S505). Although this correction process is not particularly limited, for example, the following can be considered.

  (1) The calculated travel distance “lu” itself is corrected.

  (2) A correction coefficient “r2” for correcting the distance coefficient “R” is calculated according to the counted number of pulses, and the travel distance is calculated by the distance coefficient “R”, the correction coefficient “r2”, and the number of pulses “Cp”. calculate.

  (3) A new distance coefficient “R ′” is calculated according to the counted number of pulses, and the travel distance is calculated based on the distance coefficient “R ′” and the number of pulses “Cp”.

  In the case of (1) above, the travel distance calculated in the process of S304 before that is corrected. In the cases (2) and (3) above, the travel distance calculated in the process of S304 before that may be corrected, and the travel distance calculated in the process of S304 thereafter may be corrected. .

  The camera control unit 143 instructs the camera 110 to end shooting by outputting a predetermined command to the camera 110. The camera 110 finishes shooting in accordance with the command (S506).

  Thus, in the navigation system 1 of the present embodiment, the travel distance of the vehicle can be corrected with a dotted line. This makes it possible to correct the travel distance error without traveling a certain distance. In addition, the camera power can be turned off after detecting the white line.

As described above, after correcting the travel distance, the current position calculation unit 141 calculates the display candidate point again using the corrected travel distance, and displays the calculated new display candidate point on the display 107 or the like. It may be output.
<Second Embodiment>
Next, a second embodiment will be described.

  An embodiment for correcting the travel distance of a vehicle from the time during traveling between kilometer posts on an expressway will be described. Here, “kilo post” indicates a distance from an interchange or the like on a highway. On the highway, the kilometer posts are installed at 100m intervals, and this distance is the same everywhere.

  The second embodiment is different from the first embodiment described above only in that the detection target is a kilopost, and the other is the same.

  An operation example of the second embodiment will be described. In the following description, only an operation example different from the operation example of the first embodiment will be described in detail.

  The operation example described below is activated at predetermined time intervals, for example, every 0.1 second.

  The activation determination unit 142 is activated every predetermined time and determines whether or not the current position of the vehicle is on the expressway (S701). For this purpose, the activation determination unit 142 selects, for example, the link information 203 including the link ID 211 of the link having the display candidate point calculated by the above-described processing from the map information table 201, and is included in the selected link information. It is determined whether or not the road type 214 is “highway”.

  If the current position of the vehicle is not on the highway as a result of the determination in S701, the activation determination unit 142 ends the process.

  As a result of the determination in S <b> 701, when the current position of the vehicle is on the highway, the activation determination unit 142 instructs the camera control unit 143 to activate the camera 110. In accordance with the instruction, the camera control unit 143 outputs a predetermined command and instructs the camera 110 to start photographing. The camera 110 starts shooting (S702).

  The camera 110 inputs the captured image to the navigation system 1.

  The rotation speed acquisition unit 144 performs image processing on the input image and determines whether a kilopost is detected (S703). This image processing is the same as the prior art, and a specific method is arbitrary. For example, it is preferable to detect kiloposts by pattern matching.

  If the result of the determination in S703 is that a kilometer post is not detected, the camera control unit 143 performs a process in S706 described later.

  As a result of the determination in S703, when the kilopost is detected, the rotation speed acquisition unit 144 acquires the number of pulses from one kilopost to the next kilopost (S704). Although this specific process is not particularly limited, for example, a pulse value is acquired by the counter 122 from when a kilopost is detected in a certain image until the kilopost is detected in a subsequent image. This specific operation example is the same as in the first embodiment described above.

  The correction unit 145 corrects the travel distance of the vehicle according to the number of pulses acquired in the above-described processing of S704 (S705). This specific correction example is the same as that in the first embodiment.

  The camera control unit 143 instructs the camera 110 to end shooting by outputting a predetermined command to the camera 110. The camera 110 finishes shooting in accordance with the command (S706).

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

  For example, in the first embodiment described above, the number of pulses of a white line between a certain blank portion and the next blank portion is acquired. However, the present invention is not limited to this. You may acquire the pulse number between white line parts. Alternatively, the number of pulses while traveling between one blank portion or the number of pulses while traveling between one white line portion may be acquired. Further, the number of pulses between a certain blank part and a plurality of subsequent blank parts may be acquired. The same may be applied to the kilometer post of the second embodiment.

In one Embodiment of this invention, it is a figure which shows the structural example of a navigation system. In the embodiment, it is a figure for demonstrating an example of map data. In the same embodiment, it is an operation example which shows the outline | summary in which a navigation system calculates a present position. In the embodiment, it is an operation example for calculating a current position. In the embodiment, the navigation system is an operation example for correcting the travel distance. In the same embodiment, it is a figure explaining the detection of the white line part of a white line, and the blank part. In 2nd Embodiment, it is an operation example which a navigation system correct | amends a travel distance.

Explanation of symbols

  1: navigation system, 101: angular velocity sensor, 102: vehicle speed sensor, 103: arithmetic unit, 104: GPS receiver, 105: secondary storage device, 106: input device, 107: display, 108: audio output device, 109: Communication interface, 110: camera, 121: AD converter, 122: counter, 123: RAM, 124: ROM, 125: CPU, 141: current position calculation unit, 142: activation determination unit, 143: camera control unit, 144: Rotation speed acquisition unit, 145: correction unit

Claims (4)

An on-vehicle device mounted on a vehicle that moves with the rotation of a wheel,
A camera for photographing the road surface on which the vehicle travels;
A travel distance calculating means for calculating the travel distance of the vehicle according to the number of rotations of the wheel for a predetermined time and the set distance coefficient;
When the vehicle is traveling on an expressway, from the image data acquired by the camera, the wheel of the wheel while traveling on at least one of the dotted white line portion and the blank portion drawn on the road surface on the expressway An in-vehicle device characterized by acquiring a rotational speed and correcting a travel distance of the vehicle from the acquired rotational speed of a wheel. An on-vehicle device mounted on a vehicle that moves with the rotation of a wheel,
A camera,
A travel distance calculating means for calculating the travel distance of the vehicle according to the number of rotations of the wheel for a predetermined time and the set distance coefficient;
When the vehicle is traveling on a highway, from the image data acquired by the camera, the number of rotations of the wheel while traveling between kiloposts on the highway is acquired, and from the acquired number of rotations of the wheel An on-vehicle device characterized by correcting the travel distance of the vehicle. A mileage correction method by an in-vehicle device mounted on a vehicle that moves with the rotation of a wheel,
In the in-vehicle device having a camera for photographing the road surface of the road on which the vehicle travels,
Calculating the travel distance of the vehicle according to the number of rotations of the wheel for a predetermined time and the set distance coefficient;
When the vehicle is traveling on an expressway, from the image data acquired by the camera, the wheel of the wheel while traveling on at least one of the dotted white line portion and the blank portion drawn on the road surface on the expressway And a step of correcting the travel distance of the vehicle based on the obtained rotational speed of the wheel. A mileage correction method by an in-vehicle device mounted on a vehicle that moves with the rotation of a wheel,
In-vehicle device having a camera that captures the road surface of the road on which the vehicle travels,
A travel distance calculating step for calculating the travel distance of the vehicle according to the number of rotations of the wheel for a predetermined time and the set distance coefficient;
When the vehicle is traveling on a highway, from the image data acquired by the camera, the number of rotations of the wheel while traveling between kiloposts on the highway is acquired, and from the acquired number of rotations of the wheel And a step of correcting the travel distance of the vehicle.

Images