JP3679449B2 - Method for correcting display position of current position in current position calculation device and current position calculation device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a current position calculation device that is mounted on a moving body such as a vehicle, measures a travel distance, a traveling direction, and the like, calculates a current position of the vehicle from these, and displays it together with a road map around the current position. In particular, the present invention relates to a technique for correcting the display position of the current position on a map when the calculated current position is incorrect.
[0002]
[Prior art]
Conventionally, the current position of the vehicle is sequentially calculated based on the traveling direction of the vehicle measured by an orientation sensor such as a gyro and the travel distance of the vehicle measured by a vehicle speed sensor or a distance sensor, and the position corresponding to the calculated current position is obtained. The current position on the road map displayed on the display device is updated. According to such a technique, as the vehicle moves, the current position display moves smoothly on the map. From this display, the driver can determine the current position of the vehicle, the traveling direction on the map, the driving situation, etc. Can be grasped immediately.
[0003]
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.
[0004]
Further, in order to correct the error of the current position obtained from the traveling direction and the travel distance of the vehicle in this way, the vehicle that is obtained so as to be consistent with the road data as in the technique described in Japanese Patent Publication No. 6-13972. A so-called map matching technique for correcting the current position of the image is known. According to this map matching technique, the accuracy of position calculation can be increased.
[0005]
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.
[0006]
Such a measurement error of the travel distance can be corrected to some extent by the above-described map matching technique when traveling on a normal road. However, when driving on a road such as an expressway, since the road does not have features such as curves and intersections that can be used for map matching, the error cannot be corrected sufficiently.
[0007]
Furthermore, once an error of about 1 km occurs between the measured current position and the true current position, it is difficult to correct the position correctly depending on the map matching technique.
[0008]
Therefore, in order to eliminate the measurement error of the travel distance, conventionally, it is obtained from (1) road data from the time when the intersection is turned (start point) to the next intersection (end point) and the measured rotation speed. The distance coefficient per one rotation of the tire has been corrected by comparing with the travel distance. Also, as described in (2) JP-B-6-27652, a technique for correcting the above-described distance coefficient by comparing the distance on the map between the two beacons and the distance measured by running. Is also known.
[0009]
[Problems to be solved by the invention]
Now, because the distance coefficient does not always have a value that can calculate the correct travel distance, a position that is advanced or delayed from the actual current position is erroneously calculated as the current position and displayed on the map. Have been.
[0010]
In such a case, if the display of the current position on the map is corrected to the correct position at once, the current position may be moved discontinuously on the map or moved in the direction opposite to the traveling direction. This will cause unnatural and mysterious behavior that is different from the driving of the driver, causing confusion to the driver.
[0011]
Therefore, an object of the present invention is to correct the display of the current position on the map represented on the display device so that the user can feel it more naturally.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention sequentially calculates the travel distance of the vehicle according to the detected wheel rotation speed and the set distance coefficient, and detects the detected travel distance of the vehicle. In a current position calculation device mounted on a vehicle that moves as the wheels rotate, the current position where the vehicle exists is calculated according to the traveling direction of the vehicle, and the calculated current position is displayed together with a road map around the current position. A method of correcting the display position of the current position on the road map when the calculated current position is incorrect, and is set in the travel distance calculating means when the calculated current position is incorrect The displayed position of the current position on the road map is corrected by correcting the calculated distance coefficient so that the current position calculated during the period until the vehicle travels a certain distance is gradually closer to the correct position. Above Provides a method of correcting the display position of the current position at the current position calculating device, characterized in that the modified progressively to.
[0013]
[Action]
According to the correction method of the display position of the current position in the current position calculation apparatus according to the present invention, instead of correcting the display position of the current position immediately when the current position is incorrect, the calculated current position is If it is behind the actual current position, the distance coefficient set in the travel distance calculation means is corrected to a larger value until the vehicle travels a certain travel distance, and the calculated current position is incorrect. If the calculated current position is ahead of the actual current position, the distance coefficient set in the travel distance calculation means until the travel of the fixed travel distance, By correcting to a smaller value, the display position of the current position on the road map is gradually corrected during the time.
[0014]
Therefore, when the current position on the map is corrected to the correct position, the current position may move discontinuously on the map, or move in the direction opposite to the traveling direction. It is possible to prevent unnatural and mysterious behavior different from
[0015]
【Example】
Hereinafter, an embodiment of a current position calculation apparatus according to the present invention will be described.
[0016]
FIG. 1 illustrates the configuration of the current position calculation apparatus according to the present embodiment.
[0017]
That is, the current position calculation device according to the present embodiment includes an angular velocity sensor 201 that detects a change in traveling azimuth by detecting the yaw rate of the vehicle, and an azimuth such as a geomagnetic sensor that detects the traveling azimuth of the vehicle by detecting geomagnetism. A sensor 202 and a vehicle speed sensor 203 that outputs pulses at time intervals proportional to the rotational speed of the output shaft of the vehicle transmission are provided.
[0018]
Further, a display 207 that displays a map around the current position, a mark indicating the current position, and the like, a switch 204 that receives a command to switch the scale of the map displayed on the display 207 from the driver, and stores digital map data A CD-ROM 205 and a driver 206 for reading map data from the CD-ROM 205. Further, a controller 208 that controls the operation of each peripheral device described above is provided.
[0019]
Next, the controller 208 includes an A / D converter 209 that converts the signal (analog) of the angular velocity sensor 201 into a digital signal, and an A / D converter 210 that converts the signal (analog) of the azimuth sensor 202 into a digital signal. The counter 216 that counts the number of pulses output from the vehicle speed sensor 203 every 0.1 second, the parallel I / O 211 that inputs whether or not the switch 204 is pressed, and the map data read from the CD-ROM 205 are transferred. A direct memory access (DMA) controller 212 and a display processor 213 for displaying a map image on the display 207.
[0020]
The controller 208 further includes a microprocessor 214 and a memory 215. The microprocessor 214 outputs signals from the angular velocity sensor 201 obtained through the A / D converter 209, signals from the direction sensor 202 obtained through the A / D converter 210, and output pulses from the vehicle speed sensor 203 counted by the counter 216. Number, whether or not the switch 204 is input via the parallel I / O 211, the map data from the CD-ROM 205 obtained via the DMA controller 212 is received, and processing based on these signals is performed. The current position is calculated and displayed on the display 207 via the display processor 213. The vehicle position is displayed by superimposing an arrow mark or the like on the map already displayed on the display 207, as shown in FIG. Thereby, the user can know the current position of the vehicle on the map. The memory 215 includes a program that defines the contents of processing (to be described later) for realizing such operations, a ROM that stores various tables to be described later, and a work area when the microprocessor 214 performs processing. RAM to be used.
[0021]
Hereinafter, the operation of the current position calculation apparatus according to the present embodiment will be described.
[0022]
First, three processes will be described: a process for calculating the traveling direction and travel distance of the vehicle, a process for determining the current position of the vehicle from the calculated traveling direction and distance, and a process for displaying the obtained vehicle position and direction.
[0023]
FIG. 3 illustrates the flow of processing for calculating the traveling direction and travel distance of the vehicle.
[0024]
This process is a routine of the microprocessor 214 that is activated and executed at a constant cycle, for example, every 100 ms.
[0025]
In this routine, first, the output value of the angular velocity sensor 201 is read from the A / D converter 209 (step 401). Since a change in direction is output as the output value of the angular velocity sensor 201, only a relative value in the traveling direction of the vehicle can be detected. Therefore, next, the output value of the azimuth sensor 202 is read from the A / D converter 210 (step 402), and the absolute azimuth calculated based on the output value of the azimuth sensor 202 and the azimuth change output from the angular velocity sensor 201 ( The estimated azimuth of the vehicle is determined using (angular velocity output) (step 403).
[0026]
For example, when the vehicle speed is low for a long time, the angular velocity sensor 201 has a large error. Therefore, when the vehicle speed is low for a certain time or more, only the direction output by the direction sensor 202 is used. .
[0027]
Next, the number of pulses output from the vehicle speed sensor 203 is counted by the counter 216 every 0.1 second, and the counted value is read (step 404). By multiplying the read value by a distance coefficient R, a distance advanced in 0.1 seconds is obtained (step 405). A method for obtaining the distance coefficient R will be described later.
[0028]
Next, the travel distance value per 0.1 second obtained in this way is added to the previously obtained value to check whether the travel distance of the vehicle has reached 20 m (step 406). If not (No in step 406), the current process is terminated and a new process is started.
[0029]
As a result of the travel distance calculation process, when the accumulated travel distance becomes a certain distance, for example, 20 m (Yes in Step 406), the traveling direction and the travel distance (20 m) at that time are output (Step 407). In step 407, the accumulated distance is further initialized, and accumulation of the travel distance is newly started.
[0030]
Next, processing for obtaining the current position of the vehicle based on the calculated traveling direction and travel distance will be described.
[0031]
FIG. 4 shows the flow of this process.
[0032]
This processing is a routine of the microprocessor 214 that is activated and executed in response to the output of the traveling direction and travel distance from FIG. That is, this process is started every time the vehicle travels 20 meters.
[0033]
In this process, first, the traveling direction and the travel distance output in step 407 are read (step 501). Next, based on these values, the movement amount of the vehicle is obtained separately in the latitude and longitude directions. Further, the movement amount in each direction is added to the current position of the vehicle obtained in the previous process to obtain the current position (A) (step 502).
[0034]
If there is no previously obtained position, such as immediately after the start of the device, the current position (A) is obtained using the separately set position as the previously obtained position.
[0035]
Next, a map around the obtained current position (A) is read from the CD-ROM 205 via the driver 206 and the DMA controller 213, and within a preset distance D centered on the current position (A). Some road data (line segment) is extracted (step 503).
[0036]
As the road data, for example, as shown in FIG. 6, a plurality of line segments 81 to 85 that connect two points are approximated, and those line segments are expressed by the coordinates of the start point and the end point. be able to. For example, the line segment 83 is expressed by its start point (x3, y3) and end point (x4, y4).
[0037]
Next, from the line segments extracted in step 503, only those line segments whose azimuth is within the predetermined traveling direction and predetermined value are extracted (step 504). Further, a perpendicular is drawn from the current position (A) for all the extracted line segments, and the length of the perpendicular is obtained (step 505).
[0038]
Next, the error cost value defined below is calculated for all the line segments extracted in step 504 using the lengths of the perpendicular lines.
[0039]
Error cost = α × | Advance direction−Line segment direction | + β | Length of perpendicular |
Here, α and β are weighting factors. The values of these coefficients may be changed depending on whether the current position is important in selecting the road on which the current position or the road is shifted, or the current position or the road is shifted. For example, when importance is attached to a road whose direction is close to the traveling direction, α is increased.
[0040]
When the error cost of each line segment is calculated, the line segment with the smallest error cost value is selected from the line segments for which the error cost has been calculated (step 506), and the line segment and the perpendicular line are selected. The intersecting point (the bottom of the vertical line) is set as the corrected current position (B) (step 507).
[0041]
Incidentally, in step 503 described above, road data (line segment) within a preset distance D centered on the current position (A) is extracted. This distance D was selected in the previous step 506. It may be a value determined based on the value of the road error cost.
[0042]
Here, the reason for obtaining the search range based on the error cost is that if the error cost is large, the reliability of the accuracy of the current position (B) obtained last time is considered to be low. This is because searching for a road is more appropriate for finding the correct current position.
[0043]
Next, processing for displaying the obtained vehicle position and direction will be described.
[0044]
FIG. 5 shows the flow of this process.
[0045]
This process is a routine of the microprocessor 214 that is activated and executed every second.
[0046]
First, it is determined by checking the contents of the parallel I / O 211 whether the switch 204 is instructed to change the scale of the map (step 601). If it has been pressed (Yes in step 601), a predetermined scale flag is set correspondingly (step 602).
[0047]
Next, the current position (B) obtained in the process of FIG. 4 is read (step 603), and a map of a scale corresponding to the contents of the scale flag switched in step 602 is displayed on the display 207, for example, FIG. The screen is displayed in such a state (step 604).
[0048]
Then, the current position (B) of the vehicle and the traveling direction of the vehicle are displayed using, for example, the arrow symbol “↑” as shown in FIG. 2 (step 605). Finally, a north mark indicating north and a distance mark corresponding to the scale are displayed as shown in FIG. 2 so as to be superimposed on these (step 606).
[0049]
In the present embodiment, the vehicle position and direction are indicated by using the arrow symbols as described above. However, in the display form of the vehicle position and direction, the display state is clearly shown for the position and the traveling direction. If it exists, the form may be arbitrary. The same applies to the north mark and the like.
[0050]
Hereinafter, how the display position of the display of the current position (arrow in FIG. 2) is corrected in the present embodiment when the current position is incorrect will be described.
[0051]
As described above, the travel distance of the vehicle is obtained by multiplying the number of pulses output from the vehicle speed sensor 203 by the distance coefficient R. However, since the travel distance of the vehicle per one rotation of the tire changes due to tire wear or the like, the distance coefficient R does not always have a correct value for correctly calculating the travel distance. If the correct travel distance cannot be calculated by the distance coefficient R, a position advanced or delayed from the actual position is calculated and displayed as the current position.
[0052]
Therefore, it is determined whether or not the displayed current position is correct. If the current position is incorrect, it is necessary to correct the calculated and displayed current position so that it is correct.
[0053]
In this embodiment, it is determined as follows whether or not the displayed current position is correct.
[0054]
Now, it is assumed that the current position (B) output at step 508 in FIG. 4 travels on the road A in FIG. On the other hand, for example, the current vehicle position obtained from the traveling distance of the traveling direction of the vehicle on the basis of the point a of the current position (B) that is sequentially output, a predetermined distance before the starting point o of the traveling curve. Assume that the position trajectory is a trajectory that starts to bend from a point where the point o is over, as indicated by a broken line in the figure.
[0055]
In this case, it can be estimated that the distance coefficient R is larger than the true value. This is because at the time when it is estimated using the distance coefficient R that the vehicle has reached the curve, it is considered that the vehicle has not reached the curve because the vehicle has not started to turn. Further, the degree that the distance coefficient R is larger than the true value can be estimated from the distance d in the figure that represents the distance between the point where the vehicle actually starts to turn and the curve start point o.
[0056]
Conversely, when the trajectory of the current position of the vehicle obtained from the travel distance in the traveling direction of the vehicle is a trajectory that starts to bend before reaching the intersection point o, the distance coefficient R is smaller than the true value. Can be estimated. This is because it is considered that the vehicle has already reached the curve o because the vehicle has started to bend before it is estimated using the distance coefficient R that the vehicle has reached the curve o. is there. Also in this case, the degree to which the distance coefficient R is smaller than the true value can be estimated from the distance error d in the figure representing the distance between the point where the vehicle actually starts to turn and the curve o.
[0057]
Accordingly, it is possible to determine the direction and degree of deviation from the true value of the distance coefficient R from d in the figure. Then, if the direction of deviation from the true value of the distance coefficient R and the degree thereof are known, it is determined whether the position calculated as the current position is a position delayed from the actual position or an advanced position. Can be estimated together with its degree. For example, if the distance coefficient R is smaller than a true value, the current position calculated and displayed can be estimated as a position delayed from the actual position, and if the distance coefficient R is larger than a true value, the calculated and displayed It can be estimated that the current position being advanced is a position advanced from the actual position. Further, it can be expected that the degree of delay advancement tends to be proportional to the amount of deviation from the true value of the distance coefficient R. That is, the calculated degree of delay advancement of the current position can be expected to be a value corresponding to the distance error d.
[0058]
Therefore, in the present embodiment, when the distance error d is detected in this way, the displayed current position is a position advanced or delayed from the actual position according to the value of the distance error d. It is determined whether it is. Further, a correction variable Rsh is introduced and a distance coefficient is defined by R = R0 × (1 + Rsh). Then, when the distance error d is calculated, the value corresponding to the distance error d is set to Rsh only for 300 m thereafter, and then Rsh = 0 until the distance error d is calculated next. The calculated and displayed current position is gradually adjusted to the correct position within 300 m after the calculation. Note that R0 may be an initial value of the distance coefficient, or may be a distance coefficient corrected by the above-described conventional technique. Note that R0 may be sequentially corrected according to the distance error d. This is because, as described above, the direction of the deviation from the true value of the distance coefficient R and its degree can be determined from the distance error d.
[0059]
In addition, from the difference between the direction of the vehicle and the road, it is assumed that the vehicle has started to bend before the vehicle has reached the curve o, or that the vehicle has reached the curve o before being estimated using the distance coefficient R. You may make it determine whether the vehicle started to bend after the time estimated using the distance coefficient R. In this case, the degree by which the distance coefficient R deviates from the true value can be obtained from the integrated value of the difference between the vehicle direction and the road direction. Therefore, in this case, the correction variable Rsh can be obtained from the integrated value of the difference between the vehicle direction and the road direction.
[0060]
The details of the process executed by the microprocessor 214 in order to correct the deviation of the display position of the current position from the actual position as described above will be described below.
[0061]
First, when the present apparatus is activated, first, as shown in FIG. 8, various parameters used in the subsequent processing are initialized. That is, the distance error d is set to 0, the correction variable Rsh is set to 0, and the correction execution distance l is set to 0.
[0062]
Thereafter, the process shown in FIG. 9 is executed every time the vehicle travels 20 m.
[0063]
In the process of FIG. 9, first, the travel distance and traveling direction calculated using 201, 202, and 203 are read into each sensor as sensor data (step 701). Next, the map data read from the CD-ROM 205 to the driver 206 is read (step 702).
[0064]
Next, the distance error d shown in FIG. 7 is obtained using the sensor data read in step 701 and the map data read in step 702 (step 703), and it is determined whether or not the obtained distance error d is zero. (Step 704), if it is 0, the process is terminated. On the other hand, if d is not 0, the correction variable Rsh is set (step 705) and the process is terminated.
[0065]
Hereinafter, the details of the processing of each step will be described.
[0066]
First, the process for calculating the distance error d in step 703 will be described.
[0067]
FIG. 10 shows the procedure of this process.
[0068]
As shown in the figure, in this process, first, it is determined whether or not the correction variable Rsh is 0 (step 801).
[0069]
If it is not 0, the previously obtained Rsh is still effective (since it has not traveled 300 m after calculating the previous distance error and Rsh), the distance error d for obtaining a new correction variable Rsh The process ends without performing the calculation. Accordingly, the distance error used for obtaining the correction variable Rsh last time is continuously maintained as the distance error d. Therefore, in this case, it is determined to be “yes” by the determination step of Step 704 in FIG. 9, and the Rsh setting process of Step 705 is executed.
[0070]
On the other hand, if it is 0, it is first determined whether or not the vehicle has turned left or right (step 802), whether or not a distance error exists (step 803), and if there is a distance error, The distance error d described above is calculated (step 804). However, at this time, the sign of the distance error d is negative when the vehicle goes around the curve, and the sign of the distance error d is positive when the vehicle goes around the curve.
[0071]
On the other hand, if the vehicle is not turning right or left, or if there is no distance error, the process is terminated.
[0072]
Next, the process for setting the correction variable Rsh in step 705 of FIG. 9 will be described.
[0073]
FIG. 11 shows a processing procedure for setting the correction variable Rsh.
[0074]
In this process, first, it is determined whether or not the distance correction variable Rsh is 0 (step 1101). If it is 0, since the previously obtained correction variable Rsh has already been reset, a new correction variable Rsh corresponding to the distance error d is obtained (step 1102).
[0075]
That is, the sign of the correction variable Rsh is determined according to the correspondence shown in FIG. 12, and the absolute value of the correction variable Rsh is obtained by multiplying the absolute value of the distance error d by a predetermined coefficient j.
[0076]
Finally, the correction execution distance l is initialized to 0 (step 1103), and the process ends.
[0077]
After this, the corrected execution distance l is the value that represents the travel distance after being initialized at step 1103 until the vehicle travels 300 m after being initialized at step 1103.
[0078]
On the other hand, if it is determined in step 1101 that the distance correction variable Rsh is not 0, the correction variable Rsh obtained last time is still valid, so it is determined whether or not the correction execution distance l is 300 m or less ( In step 1404), if it is 300 m or less, the value of the corrected execution distance l is updated to represent the travel distance after being initialized in step 1103 (step 1105).
[0079]
On the other hand, if it exceeds 300 m, the correction variable Rsh is reset to 0, the correction execution distance l is reset to 0, and the distance error d is reset to 0 (step 1106).
[0080]
When the distance error d is detected by the processing described above, the correction variable Rsh is obtained according to the value of the distance error d, and thereafter, the distance coefficient R is corrected by the obtained correction variable Rsh only for 300 m, and then Rsh is calculated. Reset to zero. Further, it is possible to prevent a new correction variable Rsh from being obtained during this 300 m.
[0081]
That is, when the correction variable Rsh is reset in the process of FIG. 9, the distance error d is obtained in step 703 (FIG. 10). If the obtained distance error d is not 0, a correction variable Rsh is obtained in step 705 (FIG. 11). However, when the correction variable Rsh has not been reset, a new distance error d is not obtained in the distance error d calculation process in step 703 in FIG. 9 (see step 801 in FIG. 10), and the distance used to obtain the previous Rsh. The error d continues to be maintained. Accordingly, when the correction variable Rsh is not reset, it is determined as yes in step 704 in FIG. 9, and only the correction execution distance l is updated in step 705 (FIG. 11) until the correction execution distance l reaches 300 m. . When 300 m is reached, the correction variable Rsh and the correction execution distance are reset in the same step. The update of the correction execution distance l and the correction variable Rsh and the correction execution distance are not reset when Rsh has already been reset.
[0082]
In this way, by correcting the distance coefficient R using the correction variable Rsh, the display of the current position on the map displayed on the display 207 by the above-described processing (FIGS. 3 to 5) is 300 m as described above. In the meantime, it gradually approaches the correct position little by little. Therefore, discontinuous jumping of the current position display and reverse return do not occur.
[0083]
【The invention's effect】
As described above, according to the present invention, there is provided a current position calculation device capable of correcting the display of the current position on the map represented on the display device so that the user can feel it more naturally. Can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a current position calculation apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a display example of a map and a current position performed in one embodiment of the present invention.
FIG. 3 is a flowchart showing a procedure for calculating a traveling direction and a distance performed in an embodiment of the present invention.
FIG. 4 is a flowchart showing a procedure of a current position calculation process performed in an embodiment of the present invention.
FIG. 5 is a flowchart showing a procedure of a current position display process performed in an embodiment of the present invention.
FIG. 6 is a diagram showing a road expression format in map data used in an embodiment of the present invention.
FIG. 7 is a diagram showing a distance error d used in one embodiment of the present invention.
FIG. 8 is a first flowchart showing a processing procedure for correcting a distance coefficient performed in an embodiment of the present invention.
FIG. 9 is a second flowchart showing a processing procedure for correcting a distance coefficient performed in an embodiment of the present invention.
FIG. 10 is a third flowchart showing a processing procedure for correcting a distance coefficient performed in an embodiment of the present invention.
FIG. 11 is a fourth flowchart showing a processing procedure for correcting a distance coefficient performed in an embodiment of the present invention.
FIG. 12 is a diagram showing a positive / negative relationship between a distance error d and a correction variable Rsh used in one embodiment of the present invention.
[Explanation of symbols]
201 Angular velocity sensor 202 Direction sensor 203 Vehicle speed sensor 204 Switch 205 CD-ROM
206 CD-ROM driver 207 Display 208 DMA controller 214 Microprocessor 215 Memory

Claims (3)

  Map data storage means for storing map data representing a road map;
  Travel distance calculating means for calculating the travel distance of the vehicle from the number of rotations of the wheels using a distance coefficient for each predetermined period;
  Traveling direction detecting means for detecting the traveling direction of the vehicle for each predetermined period;
  On the road map represented by the map data using the travel distance calculated by the travel distance calculation means, the travel direction detected by the travel direction detection means, and the map data stored in the map data storage means Current position calculating means for sequentially calculating the current position of the vehicle at
  Display means for displaying an image representing the current position calculated by the current position calculating means on the road map represented by the map data;
  A right / left turn detection means for detecting a right / left turn of the vehicle from a travel direction detected by the travel direction detection means;
  Using the map data stored in the map data storage means, the difference between the point on the road map corresponding to the right / left turn detected by the right / left turn detection means and the current position calculated by the current position calculation means Distance error calculating means for calculating a distance error representing
  Correction coefficient calculation means for calculating a correction coefficient according to the distance error calculated by the distance error calculation means,
  The travel distance calculating means includes
  The number of rotations of the wheel using the distance coefficient and the correction coefficient calculated by the correction coefficient calculation means from when the right / left turn detection means is detected until the travel distance calculation means calculates a predetermined distance. To calculate the mileage of the vehicle from
  From the time when the travel distance calculating means calculates the predetermined distance to the time when the right / left turn detection means newly detects a right / left turn, the travel distance of the vehicle is calculated from the rotational speed of the wheel using the distance coefficient. To calculate
  A current position calculation device characterized by the above.   The current position calculation device according to claim 1,
  The distance coefficient is a fixed value
  A current position calculation device characterized by the above.   The current position calculation device according to claim 1,
  The distance coefficient is a value corresponding to the distance error calculated by the distance error calculation means.
  A current position calculation device characterized by the above.

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