JP2000121718A - Present position detecting equipment and method for present position detection, and program recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide present position detecting equipment or the like which can accurately detect a present position without being affected by errors intentionally included in GPS information and errors based on characteristic or the like of a GPS module. SOLUTION: In a step SB1, the latitude and longitude of a present position are taken in, which are corrected (step SB2), on the basis of error information (difference between known actual latitude and longitude and detected latitude and longitude) stored in an error information storing area. On the basis of the corrected latitude and longitude of the present position, map data containing this spot are read from a map storing part and displayed on a monitor (step SB3). Further, the present position is displayed at a position corresponding to corrected result information on the maps, that is, a position corresponding to the latitude and longitude of the corrected present position (step SB4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current position detecting device and a current position detecting method for detecting a current position, and a program recording medium storing a program for causing a computer to detect the current position.

[0002]

2. Description of the Related Art Conventionally, a GPS device has been known as a device for detecting a current position and displaying the current position. This GPS
The device includes a GPS module, a map data storage unit and a display unit.
Acquire latitude / longitude data of the current position based on the information.
Then, a map based on the map data is displayed on the display unit, and the current position based on the latitude / longitude data of the current position is displayed on the map.

[0003]

However, the GPS information sent from the satellite is originally intended for military purposes but is diverted to civilian use, and error information is intentionally included in this civilian GPS information. include. Therefore, the latitude / longitude data of the current position based on the private GPS information necessarily includes an error. Therefore, there is an error between the current position display based on the latitude / longitude data and the actual current position. Will happen. In addition, the GPS of each GPS device
Modules have different characteristics and usage environments (temperature,
An error inevitably occurs depending on the humidity, vibration, etc.). Therefore, even if there is no intentional error in the GPS information, an error may occur between the current position based on the GPS information and the actual current position. Was something.

The present invention has been made in view of such conventional circumstances, and accurately determines the current position without being affected by errors intentionally included in GPS information or errors based on characteristics of the GPS module. It is an object of the present invention to provide a current position detecting device and a current position detecting method capable of detecting, and a recording medium recording a program for causing a computer to detect a current position.

[0005]

According to the present invention, there is provided a current position detecting apparatus, comprising:
As shown in FIGS. 3 and 4, input means (13) for inputting position information of a known point, position information obtaining means (1, 2) for obtaining position information of a current position, Means for detecting in advance an error between the position information obtained at the point and the position information input by the input means, based on the error previously detected by the error detection means; Correction means (4, SB2) for correcting the position information acquired by the position acquisition means. Therefore, the error between the position information of the known point and the position information actually acquired by the position information acquisition unit is detected in advance by the error detection unit, and the position information acquired by the position information acquisition unit is thereafter determined based on this error. It is corrected by the correction means. Therefore, even if there is an intentional error or an unavoidable error due to characteristics in the position information obtained by the position information obtaining means, the position information of the current position is accurately obtained without being affected by these errors. It becomes possible.

In the present position detecting device according to the second aspect, as shown in FIG. 7, the position information obtaining means obtains position information at the point a plurality of times (SC5 to SD5).
12), the error detecting means detects an average error between the plurality of pieces of position information obtained at the point by the position information obtaining means and the position information input by the input means (SC1)
3) The correcting means corrects the position information based on the average error detected by the error detecting means.
Therefore, when the position information is acquired a plurality of times at the point, even if there is an error due to disturbance in any of the position information, the error due to the disturbance is reduced by detecting the average error. Therefore, it is possible to accurately obtain the position information of the actual current position without being affected by not only an intentional error of the acquired position information and an unavoidable error due to the characteristics of the device, but also an error due to disturbance.

Further, in the present position detecting device according to the third aspect, as shown in FIG. 9, the input means inputs position information of a plurality of known points (SD2 to SD1).
2) The error detecting means detects an average error between the plurality of pieces of position information obtained at each of the plurality of points by the position information obtaining means and the corresponding position information input by the input means (SD13), The correcting means corrects the position information based on the average error detected by the error detecting means. Therefore, when the position information is acquired a plurality of times at the point, even if there is an error in the position information due to a difference in altitude or the surrounding environment, the error due to the surrounding environment is detected by detecting the average error. Be relaxed. Therefore, it is possible to accurately obtain the position information of the actual current position without being influenced by not only an intentional error of the acquired position information and an unavoidable error due to the characteristics of the device, but also an error due to the surrounding environment. Becomes

According to a fourth aspect of the present invention, as shown in FIGS. 1, 4 and 5, a display means (12) and a map data storage means for storing map data. (9) control means (SB4) for causing the display means to display a map based on the map data and displaying a current position (P) on the map based on the position information corrected by the correction means; Is further provided. Therefore, the current position can be accurately displayed on the map without being influenced by an intentional error of the acquired position information or an unavoidable error due to the characteristics of the device.

According to a fifth aspect of the present invention, as shown in FIGS. 3 and 4, an input process (SA1) for inputting location information of a known point, and A position information acquisition process (SA4) for acquiring information, and an error detection process (SA7) for detecting in advance an error between the position information acquired at the point by the position information acquisition process and the position information input by the input process. A correction process (SB) for correcting the position information acquired in the position acquisition process based on the error detected in advance by the error detection process.
2) is performed. Therefore, by the error detection processing,
An error between the position information of the known point and the actually acquired position information is detected in advance, and the acquired position information is corrected based on this error, and the acquired position information is intentionally subject to errors, characteristics, and usage environment. Therefore, even if there is an error unavoidable due to the above, it is possible to accurately obtain the position information of the current position without being affected by these errors.

In the present position detecting method, as shown in FIG. 7, in the position information obtaining process, position information is obtained at the point a plurality of times (SC5 to SD).
12) In the error detection processing, an average error between the plurality of pieces of position information acquired in the position information acquisition processing and the position information input in the input processing is detected (SC13), and in the correction processing, the error detection is performed. The position information is corrected based on the average error detected by the processing. Therefore,
When the position information is acquired a plurality of times at the point, even if there is an error due to disturbance in any of the position information, the error due to the disturbance is reduced by detecting the average error, and the error due to the disturbance is also affected by the disturbance. Instead, the position information of the actual current position can be obtained accurately.

In the present position detecting method according to the present invention, as shown in FIG. 9, in the input process, known position information of a plurality of points is input (SD2 to SD1).
2) In the error detection processing, an average error between the plurality of pieces of position information obtained in the position information obtaining processing and the corresponding position information input in the input processing is detected (SD1).
3) In the correction processing, the position information is corrected based on the average error detected by the error detection processing. Therefore, when the position information is acquired a plurality of times at the point, even if there is an error in the position information due to a difference in altitude or the surrounding environment, the error due to the surrounding environment is detected by detecting the average error. As a result, the position information of the actual current position can be accurately obtained without being affected by errors caused by the surrounding environment.

In the program recording medium according to the present invention, as shown in FIGS. 3 and 4, a computer is operated by an input means (S) for inputting position information of a known point.
A1) A position information acquisition unit (SA4) for acquiring position information of a current position, and an error for previously detecting an error between the position information acquired at the point by the position information acquisition unit and the position information input by the input unit. Detecting means (SA7), based on the error detected in advance by the error detecting means,
A program for functioning as a correction unit (SB2) for correcting the position information acquired by the position acquisition unit is recorded. Therefore, an error between the position information of the known point and the actually acquired position information is detected in advance, and the acquired position information is corrected based on this error.

According to a ninth aspect of the present invention, as shown in FIG. 7, the position information acquiring means acquires the position information at the point a plurality of times (SC5 to SD12). The error detecting means detects an average error between the plurality of pieces of position information obtained at the point by the position information obtaining means and the position information input by the input means (SC7); Is based on the average error detected by the error detection means,
The position information is corrected. Therefore, when the position information is acquired a plurality of times at the point, even if there is an error due to disturbance in any of the position information, the error due to the disturbance is reduced by detecting the average error.

According to a tenth aspect of the present invention, as shown in FIG. 9, the input means inputs position information of a plurality of known points (S).
D2 to SD12), the error detecting means detects an average error between a plurality of pieces of position information obtained by the position information obtaining means at each of the plurality of points and the corresponding position information input by the input means. Yes (SD13), the correcting means corrects the position information based on the average error detected by the error detecting means. Therefore, when the location information is acquired a plurality of times at the point,
Even if there is an error in the position information due to a difference in altitude or surrounding environment, the error due to the surrounding environment is reduced by detecting the average error.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a case where the present invention is applied to a small-sized handheld type GPS device. This GPS device includes a GPS antenna 1 and a GPS
A GPS module 2 for demodulating and decoding the L1 band C / A code from the satellite received by the antenna 1 to determine the latitude and longitude of the current position;
The information on the latitude / longitude determined by the above is taken into the CPU 4 via the bus 3. The CPU 4 includes a storage device 5,
And R in which various data necessary for the operation of the CPU 4 are stored.
AM6 are connected via the bus 3, respectively.

The storage device 5 has a recording medium 14 in which programs, data and the like are stored in advance, and this recording medium 14 is constituted by a magnetic or optical recording medium or a semiconductor memory. The recording medium 14 is fixedly provided in the storage device 5 or is detachably mounted. Further, the program, data, and the like to be recorded on the recording medium 14 may be configured to be received and stored from another device connected via a communication line or the like.
A recording device having the recording medium 14 may be provided on another device connected via a communication line or the like, and a program and data stored in the recording medium may be used via the communication line. .

A graphic controller 7 and a CPU peripheral circuit G / A 8 are connected to the bus 3.
A map storage unit 9 is connected to the CPU peripheral circuit G / A8. The CPU 4 constitutes the control means of the present invention in this embodiment, and includes a CPU peripheral circuit G / A8.
The map data and the like are read from the map storage unit 9 via the CPU 11, and a map and the like are displayed on the screen of the monitor 12 based on the map data and the image information stored in the video RAM 11. Further, a key input unit 13 having various operation keys (not shown) such as a mode key, a preset key, and a memory key provided for operating the GPS device is connected to the CPU peripheral circuit G / A8. The map storage unit 9
This embodiment constitutes the map data storage means of the present invention, and stores map data.

An error information memory 6M shown in FIG. 2 is provided in a part of the RAM 6. The error information memory 6M includes an absolute position information storage area 6a for storing absolute position information input by the user in longitude and latitude, a GPS
It comprises a measured position information storage area 6b for storing information on the latitude and longitude determined by the module 2, and an error information storage area 6c for storing the difference between the two.

In the present embodiment according to the above configuration, the small-sized handy type GPS according to the present embodiment is used.
When using the device, the user carries the GPS device to a point such as an elementary school where the latitude / longitude of the point is displayed or a point where the user knows the latitude / longitude. When the vehicle reaches any of these points, the user operates the key input unit 13 to turn on the power and set the correction data creation mode.

Then, the CPU 4 realizes each function shown in the flowchart of FIG. 3 based on the control program stored in the recording medium 14 in the form of a readable program code. That is, the user operates the key input unit 1
When the latitude / longitude of the point is input as absolute position information by the key operation in step 4, the absolute position information is acquired (step SA1). Then, after the user has completed the input of the absolute position information, and operates the preset key, the process proceeds to steps SA1 → SA2 → SA3, absolute position information inputted by latitude and longitude (X _A, Y _A) error information memory a It is stored in the 6M absolute position information storage area 6a (step SA3).

Next, the C / A code in the L1 band from the satellite received by the GPS antenna 1 is demodulated and decoded, and the GPS
The current position module 2 has indexing latitude and longitude (current position information (X _B, Y _B)) acquires (step SA4),
In response to the operation of the memory key on the key input unit 13 (step SA5), the latitude / longitude information of the current position is stored in the measured position information storage area 6b (step SA5).
6). Thereafter, an error calculation process is performed (step S
_{A7), X C = X A} -X B, calculates the Y _C = Y _A -Y _B, the error is these calculation results (X _C, after displaying the Y _C) to the monitor 12 (step SA8), This error (X _C , Y _C ) is stored in the error information storage area 6c (step SA)
9).

Therefore, as shown in FIG. 2, the absolute position information (X _A , Y _A ) is stored in the absolute position information storage area 6a of the error information memory 6M, and the measured position information storage area 6b is obtained, as shown in FIG. the measurement position information measured by the current position (X _B, Y _B) are stored, the error in the error information storage area 6c (X _C, Y _C) is stored.

When the processing in the correction data creation mode is completed in this way, the user can use this G when going out.
Carry the PS device, turn on the power if necessary, and set the current position display mode. Then, the CPU 4 realizes each function shown in the flowchart of FIG. 4 based on the control program stored in the recording medium 14. That is, C
The PU 4 instructs the GPS module 2 to perform positioning, and when positioning is completed, the GPS module 2 causes the GPS module 2 to output latitude and longitude (current position information) and captures them (Step S).
B1).

If the latitude / longitude of the current position is fetched, the latitude / longitude of the fetched current position is stored in the error information (X _C , Y _C ) stored in the error information storage area 6c.
(Step SB2). That is, latitude and longitude of the current position (X _E, Y _E) if it is, X _F =
X _E + X _C, by calculating the _{Y F = Y E + Y C} , to obtain a corrected current position latitude and longitude (X _F, Y _F). Subsequently, the latitude and longitude (X _F, Y _F) of the corrected current position based on, reads the map data including the location from the map storage unit 9 and displayed on the monitor 12 (step SB3), further on the map The current position is displayed at the position corresponding to the correction result information, that is, at the position corresponding to the corrected latitude / longitude (X _F , Y _F ) of the current position (step SB4).

As a result, the monitor 12 displays a map M based on the map data and a current position mark S indicating the current position on the map M, as shown in FIG. 5A. At this time, as described above, the current position mark S
Is displayed at a position corresponding to the corrected latitude / longitude (X _F , Y _F ) of the current position. Therefore, if the current position is displayed only with the latitude / longitude information from the GPS module 2 as shown in FIG. 2A, an intentional error in the GPS information and an unavoidable error due to the characteristics of the GPS module 2 will be described. Therefore, even if an error occurs between the actual current position P and the current position mark S, G according to the present embodiment
The PS device can display the current position mark S on the actual current position P as shown in FIG.

In the case where the GPS device is mounted on a vehicle, the intentional error and the unavoidable error cause the problem shown in FIG.
As shown in (B '), even when the current position mark S moves on a movement route deviated from the movement route R, the GPS which has completed the correction creation mode processing in the present embodiment.
When the vehicle travels with the apparatus mounted on the vehicle, the processing according to the flowchart shown in FIG. 4 is repeatedly executed during the travel, so that the actual travel route R as shown in FIG.
An appropriate display in which the current position mark S moves above can be provided.

FIG. 6 shows a configuration of an error information memory 6M according to a second embodiment of the present invention. The error information memory 6M includes the absolute position information storage area 6a, the measurement position information storage area 6b, an average error storage area 6d is provided in addition to the error information storage area 6c. A plurality of measurement position information storage areas 6b and error information storage areas 6c are provided.

In this embodiment having the above-described configuration, similarly to the above-described embodiment, when using, first, a point where the latitude / longitude of the point is displayed, or the user knows the latitude / longitude. This G at a point
Carry the PS device and set the correction data creation mode. Then, the CPU 4 operates according to the flowchart of FIG. 7 based on the control program, and resets the register n (step SC3). Subsequently, after executing the same processing as steps SA to SA9 in the flowchart of FIG. 3 described above in steps SC2 to SC10, the value of the register n is incremented (step SC11).

Next, this incremented register n
It is determined whether or not the value of is “5” (step SC1).
2) The processes of steps SC5 to SC12 are repeated until n = 5. Therefore, SC5 before n = 5
To SC12 are repeated five times. As a result, as shown in FIG. 6, the measurement position information storage area 6b
, Five pieces of measurement position information (X _B1 , Y _B1 ) to (X _B5 , Y
_B5 ) is stored, and five pieces of error information ( _XC1 , _YC1 ) to ( _XC5 , _YC5 ) are also stored in the error information storage area 6.

Thereafter, an average error calculation process is performed (step SC13) to obtain five pieces of error information (X _C1 , Y _C1 ).
Average error (X _D , Y _D ) which is the average value of to (X _C5 , Y _C5 )
After calculating the average error (X _D , Y _D ) on the monitor 12 (step SC14), the average error (X _D , Y _D ) is stored in the average error information storage area 6d (step SC15).

That is, in this embodiment, after measuring the current position a plurality of times (five times) at the same point where the latitude and longitude are known and calculating the error, the average value of these errors is averaged. The error information (X _D , Y _D ) is stored in the average error information storage area 6d. Then, when executing the processing in the current position display mode of FIG.
In B2, the current position information is corrected with the average error information (X _D , Y _D ). At this time, since the average error information (X _D , Y _D ) is an average value of the errors over a plurality of times, the error due to the disturbance is also reduced. Therefore, the current position mark S is accurately displayed on the actual current position P without being influenced by not only an intentional error of the GPS information and an unavoidable error due to the characteristics of the GPS module 2 but also an error due to disturbance. Can be.

FIG. 8 shows a configuration of an error information memory 6M according to a third embodiment of the present invention. The error information memory 6M has an absolute position information storage area 6M.
The configuration in which a, the measurement position information storage area 6b, the error information storage area 6c, and the average error storage area 6d are provided is the same as that of the second embodiment shown in FIG.
A plurality of absolute position information storage areas 6a are provided similarly to the measurement position information storage area 6b and the error information storage area 6c.

The correction data creation mode processing in the present embodiment is executed according to the flowchart shown in FIG.
1 to SD15 are the same as all the steps SC1 to SC15 in the flowchart shown in FIG. However, if the result of the determination in step SD5 is n ≠ 5, the processing is repeated from step SD2, so that the processing in steps SD2 to SD12 is repeated five times until n = 5, so that step SC5 is repeated. This is different from the second embodiment in which only the processing of SC12 is repeated five times.

Therefore, step S is performed until n = 5.
By repeating the processing of D2 to SD12 five times,
As shown in FIG. 8, 5 is stored in the absolute position information storage area 6a.
Pieces of absolute value information ( _XA1 , _YA5 ) to ( _XA5 , _YA5 ) are stored, and five pieces of measurement position information ( _XB1 , _YB1 ) to ( _XB5 , Y _B5 ) is stored, and five pieces of error information (X _C1 , Y _C1 ) to
(X _C5 , Y _C5 ) is stored.

Thereafter, an average error calculation process is performed (step SD13), and five pieces of error information (X _C1 , Y _C1 ) are obtained.
Average error (X _D , Y _D ) which is the average value of to (X _C5 , Y _C5 )
After calculating the average error (X _D , Y _D ) on the monitor 12 (step SD14), the average error (X _D , Y _D ) is stored in the average error information storage area 6d (step SD15).

That is, in this embodiment, the absolute position information is input at different points where the latitude and longitude are known, and the current position is measured at each point to calculate the error. Is stored in the average error information storage area 6d as average error information (X _D , Y _D ). Then, when executing the processing in the current position display mode of FIG. 4, the current position information is corrected with the average error information (X _D , Y _D ) in step SB2. At this time, since the average error information (X _D , Y _D ) is the average value of the detection errors at a plurality of different points, errors due to the surrounding environment such as terrain and altitude are also reduced. Therefore, G
In addition to intentional errors in the PS information, inevitable errors due to the characteristics of the GPS module 2, and errors due to disturbances,
The current position mark S can be accurately displayed on the actual current position P without being affected by errors due to the surrounding environment such as the terrain and altitude.

In the embodiment, the current position is displayed on the map based on the map data. However, only the current position may be displayed in latitude and longitude without displaying the map. Further, in the embodiment, the average error of five measurements is calculated, but the number of times is not limited to this and may be larger.

[0038]

As described above, the present invention detects an error between the position information of a known point and the acquired position information in advance, and corrects the acquired position information based on the previously detected error. Therefore, even if there is an inevitable error due to intentional errors or characteristics in the acquired position information, accurate position information of the current position can be obtained without being affected by these errors. Can be.

Further, position information is acquired a plurality of times at a location where the position information is known, and the acquired position information is corrected based on an average error between the position information acquired a plurality of times and the known position information. As a result, it is possible to accurately obtain the position information of the actual current position without being influenced by not only an intentional error of the acquired position information and an unavoidable error due to the characteristics of the device, but also an error due to a disturbance.

Further, known positional information of a plurality of points is inputted, an average error with a plurality of positional information acquired at each of the plurality of points is detected, and the acquired positional information is corrected based on the average error. As a result, not only the intentional error of the acquired position information and the unavoidable error due to the characteristics of the device, but also the position information of the actual current position accurately without being influenced by the error due to the surrounding environment. Can be obtained.

In addition, since a map based on the map data is displayed and the current position is displayed based on the corrected position information on the map, intentional errors in the acquired position information and characteristics of the apparatus are obtained. The current position can be accurately displayed on the map without being influenced by unavoidable errors or the like.

[0042]

[Brief description of the drawings]

FIG. 1 is a block diagram of a GPS device according to an embodiment of the present invention.

FIG. 2 is a memory configuration diagram of a RAM according to the first embodiment.

FIG. 3 is a flowchart showing a processing procedure in a correction data creation mode according to the embodiment.

FIG. 4 is a flowchart showing a processing procedure in a current position display mode of the embodiment.

FIGS. 5A and 5B are diagrams showing display examples in the present embodiment, and FIGS. 5A and 5B are diagrams showing display examples in a conventional device.

FIG. 6 is a memory configuration diagram of a RAM according to a second embodiment.

FIG. 7 is a flowchart showing a processing procedure in a correction data creation mode according to the embodiment.

FIG. 8 is a memory configuration diagram of a RAM according to a third embodiment.

FIG. 9 is a flowchart showing a processing procedure in a correction data creation mode according to the embodiment.

[Explanation of symbols]

 2 GPS module 4 CPU 5 Storage device 9 Map storage unit 12 Monitor 14 Recording medium

Claims (10)

[Claims] An input unit for inputting position information of a known point; a position information obtaining unit for obtaining position information of a current position; a position information obtained by the position information obtaining unit at the point; Error detecting means for detecting in advance an error with the position information input by the CPU, and correcting means for correcting the position information obtained by the position obtaining means based on the error detected in advance by the error detecting means. A current position detecting device, characterized in that: 2. The position information acquiring unit acquires position information at the point a plurality of times, and the error detecting unit inputs the plurality of position information acquired at the point by the position information acquiring unit by the input unit. The current position detection according to claim 1, wherein an average error with the detected position information is detected, and the correction unit corrects the position information based on the average error detected by the error detection unit. apparatus. 3. The input means inputs position information of a plurality of known points, and the error detecting means includes a plurality of position information acquired by the position information acquiring means at each of the plurality of points and the input means. And detecting an average error with the corresponding position information input by the control unit, wherein the correction unit corrects the position information based on the average error detected by the error detection unit. Current position detection device. 4. A display unit, a map data storage unit that stores map data, and a map based on the map data displayed on the display unit, and a position corrected on the map by the correction unit. 4. The current position detecting device according to claim 1, further comprising control means for displaying a current position based on the information. 5. An input process for inputting position information of a known point, a position information obtaining process for obtaining position information of a current position, a position information obtained at the point by the position information obtaining process, and the input process. And an error detection process for detecting an error with the position information input in advance, and a correction process for correcting the position information acquired in the position acquisition process based on the error detected in advance by the error detection process. A current position detecting method, characterized in that: 6. The position information acquiring process acquires position information at the point a plurality of times, and the error detecting process includes a plurality of position information acquired in the position information acquiring process and a position input in the input process. 6. The current position detection method according to claim 5, wherein an average error with information is detected, and in the correction processing, the position information is corrected based on the average error detected by the error detection processing. 7. In the input processing, input position information of a plurality of known points, and in the error detection processing, a plurality of position information respectively obtained in the position information obtaining processing and the correspondence input in the input processing. 6. The current position detection method according to claim 5, wherein an average error with the position information to be detected is detected, and in the correction processing, the position information is corrected based on the average error detected by the error detection processing. . 8. A computer, comprising: input means for inputting position information of a known point; position information obtaining means for obtaining position information of a current position; position information obtained by the position information obtaining means at the point; Error detecting means for detecting an error with the position information input by the means in advance, and functioning as correcting means for correcting the position information acquired by the position acquiring means based on the error detected in advance by the error detecting means. A program recording medium characterized by recording the above program. 9. The position information acquisition unit acquires position information at the point a plurality of times, and the error detection unit includes a plurality of position information acquired at the point by the position information acquisition unit and the input information. Means for detecting an average error with the position information input by the means, and the correcting means corrects the position information based on the average error detected by the error detecting means. The program recording medium according to claim 8, wherein 10. The input means inputs position information of a plurality of known points, and the error detecting means includes a plurality of position information acquired by the position information acquiring means at each of the plurality of points. Detecting an average error with the corresponding position information input by the input unit; and correcting the position information based on the average error detected by the error detection unit. 9. The program recording medium according to claim 8, wherein: