JPH03148009A - Azimuth detecting apparatus mounted in vehicle - Google Patents

Abstract

PURPOSE:To detect the azimuth with high accuracy by extracting geomagnetic outputs at a point where an absolute position is detected while a terrestrial magnetism sensor is mounted in a motor vehicle, storing the processed values as correcting information and using the information for correction. CONSTITUTION:In a terrestrial magnetism sensor 101, the intensity of the terrestrial magnetism is decomposed and detected as components in two directions orthogonal to each other. A distance sensor 102 detects the running distance, and an absolute position detecting means 103 detects an absolute position by signals from a satellite. In a representative value operating means 104, outputs of the sensor 101 while the vehicle runs a predetermined distance from a point detected by the detecting means 103 are averaged, so that an average value and a variance value at the subject spot are calculated. Then, a correcting information memory means 105 stores the representative value (variance) of the outputs of the sensor 101 calculated by 104 and coordinates of the center of a circle of the geomagnetic outputs etc. as correcting information. Moreover, a central coordinate operating means 106 compares the correcting information stored in 105 with the geomagnetic output information calculated by 104, so that the advancing direction of the vehicle is calculated by 107 from the coordinates of the center newly calculated by 106 and outputs from the sensor 101.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an on-vehicle azimuth detection device that is capable of correcting errors in detected azimuth due to changes in the amount of magnetization of a vehicle body while the vehicle is running.

As a conventional vehicle-mounted orientation detection device, for example, Japanese Patent Application Laid-Open No. 63-177
There is an automobile navigator device disclosed in Japanese Patent No. 013. FIG. 4 is a block diagram showing the configuration of a conventional example,
401 is a receiving means for receiving information transmitted from a signpost; 402 is a correction means for calculating the center coordinates of the geomagnetic output circle based on the azimuth information obtained from the receiving means; 403 is a center coordinate obtained by the correction means; This is direction detection means that calculates the traveling direction of the vehicle from the output value of the geomagnetic sensor.

This conventional example is equipped with a current position detection means using a geomagnetic sensor, but since the current position of the vehicle is detected by dead reckoning, the error that naturally exists in distance and direction sensors increases with the distance traveled. Accumulated. In particular, when using a geomagnetic sensor as a direction sensor, the amount of magnetization of the vehicle body may change due to the influence of an abnormal external magnetic field. Reference coordinates (
It was necessary to accurately determine the coordinates of the center of the geomagnetic output circle.

Therefore, in the conventional example, the center coordinates of the output circle were determined using a signal indicating the road direction in which the vehicle was traveling, which was transmitted from the sign post when the sign post was magnetized. What is the above sign post?
It is a type of signal equipment installed at important points on roads, and it transmits information about the absolute position of the vehicle and road conditions to the vehicle as a signal. Hereinafter, a conventional method for correcting the output of a geomagnetic sensor will be described in detail with reference to FIG.

Signpost while driving on a road with an azimuth angle of θ1) SPI
When the vehicle receives the signal and recognizes that it is currently facing the direction of θ1, the center of the geomagnetic output circle is at the azimuth angle θ1 on the geomagnetic output plane, and the geomagnetic output value Di at that time (value on the geomagnetic output circumference) It can be seen that it lies on a straight line passing through. Similarly, while driving on a road with an azimuth of 02, sign boss)S
Find a straight line that passes through the center of the geomagnetic output circle when the F3 signal is received. By finding the intersection of these two straight lines, the center coordinates CXS C''1 of the geomagnetic output circle after magnetization were calculated.

Problems to be Solved by the Invention However, with the above configuration, if there is a local deviation in the geomagnetic field at the location where the sign post is installed, the geomagnetic output will shift, and this output will differ from the geomagnetic output plane. Since the center coordinates deviate from the straight line determined from the road direction, the calculation accuracy of the center coordinates does not improve. Additionally, the problem was that the center coordinates of the geomagnetic output circle after magnetization cannot be calculated unless signals from two signposts are received, so correction takes time.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an on-vehicle orientation detection device that can accurately and quickly correct a geomagnetic orientation sensor.

Means for Solving the Problems The present invention extracts the output of the geomagnetic sensor when the amount of magnetization is accurately determined and the absolute position is detected, and calculates the average value and variance of the output of the geomagnetic output circle. The center coordinates of the geomagnetic output circle are stored as correction information together with the center coordinates, and the center of the geomagnetic output circle is determined by comparing the average value and variance of the geomagnetic sensor output when passing the point where this correction information is stored with the correction information. This is a vehicle-mounted orientation detection device equipped with a correction means for determining coordinates.

Effect With the above configuration, correction information is created from the output of the geomagnetic sensor when actually mounted on the vehicle using the correction information storage means that stores the representative value of the output of the geomagnetic sensor and the center coordinates of the output circle of the geomagnetic sensor as correction information. This makes it possible to perform corrections that are not affected by deviations in the geomagnetic field, and to accurately determine the center coordinates of the geomagnetic output circle. Furthermore, if the object passes through even one place that has correction information, the amount of magnetization can be corrected.

Examples Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an on-vehicle orientation detection device according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a geomagnetic sensor, which separates and detects the strength of geomagnetism into components in two directions orthogonal to each other.

102 is a distance sensor that detects the distance traveled by the vehicle; 103
is an absolute position detection means, which detects the absolute position by receiving, for example, a signal from a sign post or a signal from a satellite. 10
Reference numeral 4 denotes a representative value calculation means that filters and averages the output of the geomagnetic sensor 101 while traveling a predetermined distance from the point detected by the absolute position detection means 103, and calculates the average of the output as a representative value at that point. The value and variance are calculated and output along with the latitude and longitude information of the point.

Reference numeral 105 denotes a correction information storage means, which evaluates the reliability of the data based on the representative value (variance value) of the geomagnetic sensor output calculated by the representative value calculation means 104 when the amount of magnetization is accurately determined. Then, the representative value, the center coordinates of the geomagnetic output circle, and the latitude and longitude information of the point are stored together as correction information.

106 is a center coordinate calculation means, and correction information storage means 1
The center coordinates of the geomagnetic output circle are determined by comparing the correction information stored in 05 at the point where the absolute position was detected with the geomagnetic output information obtained from the representative value calculating means 104. Reference numeral 107 denotes an azimuth detection means that calculates the traveling direction of the vehicle from the output of the geomagnetic sensor 101 and the new center coordinates calculated by the center calculation means 108.

The vehicle-mounted orientation detection device of this embodiment configured as described above will be described in detail below. Note that the representative value calculation means 104, the correction information storage means 105, and the center coordinate calculation means 1
06 and the direction detecting means 107 can be realized by hardware, but in the following, they will be implemented by a CPU.

A microcomputer consists of ROM, RAM, etc. The flowchart of the process of calculating the traveling direction of the third song 8 vehicle is shown. First, in step 301, it is determined whether or not the absolute position has been detected. If the absolute position has been detected, the process moves to step 306. If the absolute position cannot be detected, the process moves to step 302 without executing the representative value calculation process, and the direction detection process is performed. conduct. After step 306, correction processing or correction information creation processing is performed, and the direction detection processing is executed in parallel during this time as well.

From steps 306 to 308, the representative value calculation means 104
corresponds to In step 306, a predetermined distance (for example, 3
The output of the geomagnetic sensor 101 is stored in the memory until the vehicle travels 0 m). Then, in step 307, a predetermined distance (
For example, the output of the geomagnetic sensor is averaged every time the vehicle travels (for example, 50 cm).

In step 308, the average value and variance of the distance averaged values are calculated and output together with information such as the latitude and longitude of the point where the absolute position was detected. As described above, in this embodiment, the average value and variance value of data after distance averaging are used as representative values.

Next, in step 309, the reliability of the geomagnetic data at the point where the absolute position was detected is determined from the variance value. Earth's magnetic field is affected by surrounding structures and underground objects, so it strongly depends on the location. Therefore, geomagnetic data measured at the same location shows the same tendency, but sometimes the data is distorted by the influence of parked vehicles, parallel vehicles, etc. that sometimes disturb the geomagnetic field. At this time, the dispersion value is larger than normal, so when the dispersion value is greater than or equal to a predetermined value, the process is terminated without correction. In this way, when the variance value is less than or equal to the predetermined value, it is determined that the reliability is high, and the process moves to step 310. In step 310, it is checked whether the center coordinates have been accurately determined.

This can be done by comparing the orientation detected by the geomagnetic sensor with the orientation obtained from map data or external orientation information and determining whether the difference is less than a predetermined value, or the driver can determine whether magnetization correction is necessary. You may also enter whether the reliability is high by determining the reliability. If the center coordinates have been accurately determined, the process moves to step 311 to create correction information, and if the center coordinates have not been calculated, the process moves to step 313 to calculate the center coordinates.

Steps 311 and 312 correspond to the correction information storage means 105, and when the center coordinates of the geomagnetic output circle are accurately determined, the geomagnetic sensor 1 at the point where the absolute position is detected
The representative value calculation means 104 calculates a representative value from the output of 01, and calculates the representative value, the center coordinates of the geomagnetic output circle, the latitude and longitude information (1) of the point, and the correction information at that point and 1
．． memorize it. In step 311, the relationship between the average value and the center coordinates is determined. FIG. 2 is an explanatory diagram of the correction information, and in this example, the relationship between the average value of geomagnetic output and the center coordinates K xl
K y is expressed as follows.

Kx=Cx−X @@a (1)Ky=
Cy-Y...(2) However, CX1 C
y is the hV coordinate of the center of the output circle, and XlY is the XlV coordinate of the average value.

In step 312, the coordinates of the detected absolute position, KXlKY, and the variance value are stored as correction information.

From steps 313 to 315, the center coordinate calculation means 10
6, the center coordinates are calculated from the correction information and the average value output in step 308. Step 313 obtains the latitude and longitude of the point from which the geomagnetic output was extracted, as well as the mean and variance values of the geomagnetic output, as output from step 308, and uses the latitude and longitude to check whether correction information for that point is stored. . If it is stored, step 31
4, and if it is not stored, the correction process ends. In step 314, correction information K xlK y at the detected point is obtained from the correction information storage means 105.

Then, in step 315, the center coordinates are calculated as follows. The average value of the geomagnetic output value obtained this time is X9 Y
'', the estimated center coordinate CX' Cyl is obtained as follows.

Cx' = Kx + X' e * *
(3) CF' = K)'+Y' ・ ・
(4) Steps 301 to 305 correspond to azimuth detection training↓07, and the azimuth θ is calculated as follows from the center coordinates calculated by the center coordinate calculating means 106 and the output value of the geomagnetic sensor 101.

In step 302, 11 output values X1Y from the geomagnetic sensor 101 are obtained. In step 303, the center coordinates Cx5C'l of the geomagnetic output circle previously calculated by the center coordinate calculation means 106 are obtained. Then, in step 304, the orientation θ is calculated as follows.

θ=arctan ((Y-Cy)/(X-Cx))
-(5) Finally, in step 305, the orientation θ obtained through the above processing is output.

As described above, according to this embodiment, when the geomagnetic sensor is actually mounted on a vehicle, the geomagnetic output at the point where the absolute position is detected is extracted, the processed value is stored as correction information, and is used for correction. This makes highly accurate correction possible.

In this example, the average value and variance value of the data were simply calculated using the representative value calculation means, but it is also possible to calculate the average value after deleting abnormal data or calculate the representative value from the frequency distribution of the data. good.

Further, although latitude and longitude information is used to identify a point, identification information such as a number assigned to a point whose absolute position is detected may also be used.

Effects of the Invention As described above, according to the present invention, correction information indicating the relationship between geomagnetic data at a point detected by the absolute position detection means and the center coordinates of the output circle is obtained from the correction information storage means, and this information is stored. By comparing the information obtained from the geomagnetic sensor with the information obtained from the geomagnetic sensor, the direction detected by the direction detection means is corrected, making it possible to make corrections that are not affected by local geomagnetic deviations, making it possible to achieve high accuracy. Direction detection becomes possible.

Furthermore, since the amount of magnetization can be corrected if the object passes through even one place that has correction information, the correction can be made quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is an explanatory diagram showing the content of correction information of the present invention, FIG. FIG. 4 is a block diagram showing the configuration of a conventional example, and FIG. 5 is an explanatory diagram showing a method for calculating the center coordinates of a magnetic output circle in the conventional example. 101... Geomagnetic sensor, 102... Distance sensor, 10
3. Absolute position detection means, 104. Representative value calculation means,
105: Correction information storage means, 106: Center coordinate calculation means, 107: Direction detection means, 401: Receiving means,
402: Correction means, 403: Orientation detection means.

Claims (1)

[Claims] A geomagnetic sensor that separates and detects the strength of geomagnetism into components in two directions orthogonal to each other, a distance sensor that detects the traveling distance of a vehicle, an absolute position detection means that detects the absolute position of the vehicle, and the distance sensor. calculation means for calculating an average value and a variance value of the output of the geomagnetic sensor in a certain section including a point where the absolute position is detected based on the output of the absolute position detection means; and a point detected by the absolute position detection means. correction information storage means for storing, as correction information, identification information, an average value and a variance value calculated by the calculation means at the point, and the center coordinates of the output azimuth circle of the geomagnetic sensor; center coordinate calculation means for determining center coordinates from the correction information at the point and the average value and variance value at that point calculated by the representative value calculation means; and calculation by the output of the geomagnetic sensor and the center coordinate calculation means. 1. A vehicle-mounted orientation detection device, comprising orientation detection means for detecting the orientation of the vehicle from the determined center coordinates.