JPH07146351A - Position detector - Google Patents

Abstract

(57) [Abstract] [Object] To improve the position detection accuracy of a GPS-only vehicle easily and inexpensively while maintaining the advantage of GPS in a device that detects the position of a vehicle based on a GPS signal. Structure: Every time the position of the vehicle is detected based on the GPS signal, it is determined whether or not the accurate position of the vehicle is detected, in addition to this position detection (S1 and S2). If accurate vehicle position data is obtained, the error contained in the GPS signal is obtained and stored (S3 and S4). After that, for a fixed time (about 10 to 20 minutes), the position of the vehicle is calculated using data obtained by removing the error component of the GPS signal (S5 and S).
6). [Effect] Since the error contained in the GPS signal obtained as described above hardly changes for a certain period of time,
The accuracy of vehicle position detection by the GPS signal is improved within a fixed time after the error is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle based on a signal transmitted from a GPS satellite that orbits the earth.
The present invention relates to a device that detects the position of a moving body such as an aircraft or a ship.

[0002]

2. Description of the Related Art Conventionally, the current position of a vehicle traveling at an arbitrary position on a road traffic network (hereinafter, simply referred to as "vehicle position").
Say. ) Has been proposed as a device that uses a satellite navigation system (hereinafter referred to as "GPS: Global Positioning System").

In the case of using GPS, the position of one's own is detected by utilizing the Doppler shift of the radio waves from an artificial satellite (hereinafter referred to as "GPS satellite") orbiting the orbit of the earth. That is, the two-dimensional or three-dimensional position of itself is detected by measuring the propagation time of the radio waves transmitted from the plurality of GPS satellites. in this case,
If the number of GPS satellites that can receive radio waves at the same time is three, the two-dimensional position of the self is known, and if the number of GPS satellites that can receive the radio waves is four, the three-dimensional position of the self is known. .

In the position detecting device using the above GPS,
The position of the traveling vehicle is obtained by receiving the radio wave transmitted from the GPS satellite by the GPS receiver mounted on the vehicle.

[0005]

The above-mentioned conventional position detecting device adopts a method of detecting the position of the vehicle only by the GPS receiver. However, the position of the vehicle detected by only the GPS receiver has an error of about 100 m at maximum.
In this way, the error in the vehicle position detection result is
The influence of the electromagnetic layer surrounding the earth, the clock error of the GPS satellite itself, the orbital correction of the GPS satellite, and the radio waves transmitted from the GPS satellites are reflected by buildings after passing through the atmosphere, and the propagation path of the radio waves changes. It is believed that various factors occur together. Therefore, in the position detecting device that detects the position of the vehicle based only on the position data received by the GPS receiver, there is an error as described above, and which road among the plurality of roads within 100 m the vehicle exists in is determined. Cannot be specified.

However, the use of the GPS described above makes it possible to use the GPS regardless of the position of the vehicle on the earth.
GPS signals can be received by the satellite, and the position of the vehicle can be detected at any position on the earth.
PS receiver can be retrofitted to the vehicle, and GPS
Since the receiver can be easily attached to the vehicle, it has various advantages such as being easy and inexpensive, and being versatile. Due to these advantages, the use of GPS is becoming indispensable in detecting the position of the vehicle in recent years. Therefore, while maintaining the advantages of GPS described above, GP
It is desired to improve the accuracy of vehicle position detection using only the S receiver.

In order to meet the above demand, a technique called differential GPS (D-GPS: Differential-GPS) has been proposed. With this D-GPS, a receiving station that receives radio waves from each GPS satellite is built at a fixed point whose longitude and latitude are known, and this reception station detects the radio waves based on the radio waves from the GPS satellites. By detecting the position error of the mobile unit and transmitting this error information to the mobile unit,
This is a technology for improving the accuracy of detecting the position of a moving body using only a GPS receiver.

However, in order to put the D-GPS into practical use, it is necessary to build a receiving station for detecting the error included in the position detection result in various places, and it is still considerable to spread the D-GPS. It takes a period. Therefore, the present inventor corrects the vehicle position detection result at a specific time by each GPS satellite to be used, because the vehicle position detection result by only the GPS receiver includes an error. The error included in the vehicle position detection result at a specific time by each GPS satellite used can be obtained by comparing with the vehicle position obtained by another method capable of detecting I thought that the accuracy of vehicle position detection could be improved. That is, the vehicle position detection error by each GPS satellite obtained as described above hardly changes for a fixed time. Therefore, within a certain period of time, the vehicle position detection accuracy can be improved by subtracting the vehicle position detection error by each GPS satellite from the vehicle position detection result by the GPS receiver.

In view of the above technical problems, the present invention provides a GPS
An object of the present invention is to provide a position detection device that can easily and inexpensively improve the position detection accuracy of a vehicle using only GPS while maintaining the above advantages.

[0010]

Means for Solving the Problems The problem solving means according to the present invention is a device for detecting the position of a mobile body mounted on a mobile body, which is a GPS orbiting the orbit of the earth. Position detecting means for receiving a signal transmitted from a satellite and detecting the position of the moving body based on the GPS signal, and obtaining accurate position data of the moving body by a method different from the position detection based on the GPS signal. In addition, the accurate position data of the moving body is compared with the position of the moving body detected by the position detecting means to obtain an error included in the GPS signal, and the error calculating means calculates the error. After the error included in the GPS signal is calculated,
It includes position correction means for calculating the position of the moving body by using the data obtained by removing the error from the GPS signal for a certain period of time.

[0011]

In the above problem solving means, the position detecting means is
A signal transmitted from a GPS satellite that orbits the earth is received, and the position of the moving body is detected based on this GPS signal. The error calculating means obtains the accurate position data of the moving body and the position of the moving body detected by the position detecting means every time the accurate position data of the moving body is obtained by a method different from the position detection based on the GPS signal. Compare
Find the error contained in the GPS signal. The position correction means is
After the error included in the GPS signal is obtained by the error calculating means, the position of the moving body is calculated for a certain period of time using the data obtained by removing the error from the GPS signal.

The error contained in the GPS signal obtained as described above hardly changes for a certain period of time.
Therefore, the accuracy of detecting the position of the vehicle by the GPS signal is improved within a certain time after the error included in the GPS signal is calculated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a position detection device according to an embodiment of the present invention. Referring to the figure, the position detecting device of the present embodiment is mounted on a vehicle for use, and is configured to improve the positional accuracy of the vehicle while maintaining the advantage of GPS. Therefore, the position detecting device is provided with the position detection processing unit 2 that mainly detects the position of the traveling vehicle based on the position data from the GPS receiver 1. The GPS receiver 1 includes a plurality of GPS satellites 3 (1 in the figure) that orbit the earth.
Only one is shown. ) To receive the radio wave from and calculate the position data.

By the way, the vehicle position detection result based on only the position data of the GPS receiver 1 includes an error due to various factors as described above. In order to correct the error included in the vehicle position detection result only by the GPS receiver 1, the position detection processing unit 2 detects the distance sensor 4 for detecting the traveling distance of the vehicle and the traveling direction of the vehicle. Outputs from the azimuth sensor 5 and a beacon receiver 6 that receives position data and the like radiated from a beacon antenna (not shown) installed on the roadside or the like are given. Further, for the same purpose, the position detection device is provided with an image recognition processing unit 7 that recognizes the image of the peripheral information of the road while the vehicle is traveling, and the image information processed by the image recognition processing unit 7 is the position of the image information. A detection processing unit 2 is provided.

The distance sensor 4 detects the traveling distance based on the speed of the vehicle or the rotation speed of the wheels.
Wheel speed sensors, vehicle speed sensors, etc. are used. The azimuth sensor 5 detects a change in azimuth as the vehicle travels, and a geomagnetic sensor, a gyro, or a turning angular velocity sensor that detects a turning angular velocity based on a difference in the rotational speeds of the left and right wheels is used. .

The position detection processing section 2 is composed of a CPU and the like. In this position detection processing unit 2, the GPS receiver 1
In addition to the vehicle position detection using only the vehicle, so-called dead reckoning and map matching are used together to detect the vehicle position. Here, the dead reckoning is a technique for estimating the position of the vehicle from the traveling locus of the vehicle. Specifically, the position detection processing unit 2 obtains the moving distance of the vehicle based on the distance data given from the distance sensor 4, and obtains the azimuth of the vehicle based on the azimuth data given from the azimuth sensor 5. Further, the position detection processing unit 2 is previously provided with accurate initial data of the vehicle from the operation data switch 8 before the vehicle starts moving, for example. The position detection processing unit 2 estimates the position of the vehicle based on the initial data given in advance and each data of the azimuth of the vehicle and the moving distance of the vehicle. The operation data switch 8 is used to set and input various operation data such as the initial data necessary for detecting the position of the vehicle.

The map matching is a technique for correcting the estimated position of the vehicle to a position on the road map by utilizing that the position of the vehicle is always one point on the road. Specifically, when the estimated position of the vehicle is detected by the dead reckoning navigation, the position detection processing unit 2 reads a road map from the map memory 9 and collates the read road map with the estimated position of the vehicle. Correct the estimated position of the vehicle on the road map. The position of the vehicle thus detected is more accurate than the position of the vehicle detected only by the GPS receiver 1. The map memory 9 is composed of a CD-ROM or the like.

When the position data is given from the beacon receiver 6, the position detection processing unit 2 detects the position of the vehicle based on this position data. The position of the vehicle thus detected is also more accurate than the position of the vehicle detected only by the GPS receiver 1. The image recognized by the vehicle-mounted color camera 10 is given to the image recognition processing unit 7. The vehicle-mounted color camera 10 is for photographing peripheral information while the vehicle is traveling, and is installed in the front portion or the rear portion of the vehicle or both of them.

When the image picked up by the camera 10 is given, the image recognition processing section 7 converts the analog image signal given from the camera 10 into digital image data and detects the position of the vehicle from the image data. Recognize such peripheral information. As the peripheral information related to the position detection of this vehicle,
For example, road signs related to other intersections of traffic lights, road displays, and road signs indicating specific facilities such as interchanges and parking areas, road displays, and the like are used.

A dictionary memory 11 is connected to the image recognition processing section 7. The dictionary memory 11 stores all recognizable road facilities, road signs, road markings, feature quantities that take into account their colors, the average value and distribution state of the feature quantities, the order in which each feature quantity affects recognition, and the like. It is something I remember.
The image recognition processing unit 7 recognizes road signs as follows, for example.

The image recognition processing unit 7 cuts out a partial image including a road sign from the given image data,
The feature quantity necessary for recognition of road signs is extracted. The extracted feature amount is compared and compared with the feature amounts of all the markers stored in the dictionary memory 11. Then, for example, the road sign with the smallest difference is selected, and the recognition of the road sign is completed. In this way, the image information recognized by the image recognition processing unit 7 is provided to the position detection processing unit 2. Position detection processing unit 2
Then, when the image information is given, the position of the vehicle is detected based on the image information. The detected vehicle position is
It is more accurate than the position of the vehicle detected only by the GPS receiver 1.

The position detection processing unit 2 is based on the position data of the map matching or beacon receiver 6 or the image information of the image recognition processing unit 7 and is more accurate than the position of the vehicle detected by the GPS receiver 1. When the position of is detected, the accurate position of the vehicle is compared with the position of the vehicle detected by only the GPS receiver 1, and the error included in the position detection result of the vehicle detected by only the GPS receiver 1 is detected. Ask. This error calculation may be performed even when initial data is set and input by the operation data switch 8. This is because it can be considered that the accurate position of the vehicle is detected when the initial data is set and input. The vehicle position detection error using each GPS satellite 3 thus obtained hardly changes for a fixed time (about 10 to 20 minutes).

Therefore, the position detection processing unit 2 stores the vehicle position detection error, and after the error is obtained, the error is obtained from the vehicle position detection result by only the GPS receiver 1 for a certain period of time. By subtracting GP
The detection position of the vehicle is corrected only by the S receiver 1. Note that the vehicle position detection error due to only the GPS receiver 1 is
It is updated each time a vehicle position that is more accurate than the vehicle position detected by the GPS receiver 1 is detected.

When the position of the vehicle detected by only the GPS receiver 1 is corrected, the position detection processing unit 2 reads the display map data from the map memory 9, and the map related to the current location and the map on the map. The current location mark of the vehicle is generated. The map and the current position mark of the vehicle are displayed on the display unit 12. The display unit 12 is composed of a CRT or the like.

FIG. 2 is a flowchart showing the vehicle position detection processing operation. Referring to the figure, when the position detection processing operation of the vehicle is started, the position detection processing unit 2 first causes G
When the position of the running vehicle is detected based on the position data from the PS receiver 1 (step S1), aside from this position detection, the position of the vehicle more accurate than the position of the vehicle detected only by the GPS receiver 1 is detected. It is determined whether or not the position has been detected (step S2). Specifically, it is determined whether the position of the vehicle has been specified by map matching, the position data from the beacon receiver 6 has been acquired, or whether the image information regarding the position detection of the vehicle has been given from the image recognition processing unit 7. . Here, until the position data of the vehicle that is more accurate than the position of the vehicle detected by only the GPS receiver 1 is obtained based on the above items, the position detection operation of the vehicle by only the GPS receiver 1 is continued. .

On the other hand, if vehicle position data that is more accurate than the position of the vehicle detected by the GPS receiver 1 alone is obtained based on the above items (1) to (4), it is more accurate than the position of the vehicle detected by only the GPS receiver 1. When the position of the vehicle is detected, the accurate position of the vehicle is compared with the position of the vehicle detected by only the GPS receiver 1 and included in the position detection result of the vehicle detected by only the GPS receiver 1. After obtaining the error, it is stored (steps S3 and S4).

After that, the stored position detection error is subtracted from the position detection result of the vehicle by the GPS receiver 1 alone to calculate the position of the vehicle. That is, the detected position of the vehicle is corrected only by the GPS receiver 1 (step S
5). The process of calculating the position of the vehicle using the data obtained by removing the error from the position detected by the GPS receiver 1 alone is a certain time period (about 10 to 10) after the accurate position data of the vehicle is obtained. It is continuously performed until 20 minutes) (step S6). After the lapse of a certain period of time, the process is returned to the processing operation of step S1.

In the above position detecting device, when the position of the vehicle is detected based on the position data of the GPS receiver 1, it is more accurate than the position of the vehicle detected only by the GPS receiver 1 by a method other than this. If the position of the vehicle is detected, the accurate position of the vehicle is compared with the result of detecting the position of the vehicle by the GPS receiver 1 only, and the error included in the result of detecting the position of the vehicle by only the GPS receiver 1 is compared. Then, the vehicle position is calculated by subtracting the vehicle position detection error from the vehicle position detection result obtained by only the GPS receiver 1 within a certain time after the accurate vehicle position is detected. Therefore, while maintaining the advantages of GPS, GPS can be easily and inexpensively
It is possible to improve the accuracy of detecting the position of the only vehicle.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made within the scope of the present invention.

[0030]

As is apparent from the above description, according to the present invention, it is possible to easily and inexpensively maintain the advantages of GPS and to reduce the cost.
There is an excellent effect that the position detection accuracy of a vehicle using only PS can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a position detection device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a vehicle position detection processing operation.

[Explanation of symbols]

 1 GPS receiver 2 Position detection processing unit 3 GPS satellite 4 Distance sensor 5 Direction sensor 6 Beacon receiver 7 Image recognition processing unit 8 Operation data switch 9 Map memory 10 Camera

Claims (1)

[Claims] 1. A device for detecting the position of a moving body mounted on a moving body, the device receiving signals transmitted from GPS satellites orbiting the earth's orbit, Position detecting means for detecting the position of the moving body based on the GPS signal; every time accurate position data of the moving body is obtained by a method different from the position detection based on the GPS signal; After calculating the error included in the GPS signal by comparing the position of the moving body detected by the position detecting unit with the error included in the GPS signal, and the error included in the GPS signal by the error calculating unit, A position detecting device comprising position correction means for calculating the position of a moving body by using data obtained by removing the error component from the GPS signal for a certain period of time.