JPH03138521A - Vehicle position detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a vehicle position detection device applied to an in-vehicle navigator. The present invention relates to a vehicle position detection device that detects the estimated position of a vehicle based on an output mileage signal.

<Prior Art and Problems to be Solved by the Invention> An in-vehicle navigator detects the current position of a vehicle and displays the detected current position on a display together with a road map of a predetermined range.

The vehicle position detection device applied to the above-mentioned in-vehicle navigator includes: (1) a so-called dead reconnaissance system that has a mileage sensor, a geomagnetic direction sensor, and a computer, and calculates the vehicle position based on the running direction and distance;
Detecting the road on which the vehicle is traveling based on the cumulative data (trajectory data) of the vehicle position calculated by the dead reckoning method described above and the degree of similarity between the road and the road stored in the map memory. , so-called map matc navigation (Map Matc) detects the vehicle position on this road.
hing).

The above navigation also assumes that the estimated position of the vehicle is calculated based on the mileage signal output from the mileage sensor and the direction signal output from other magnetic/magnetic direction sensors. If there is an error in the data output from the sensor, accurate position detection is impossible.

In particular, the above-mentioned geomagnetic direction sensor detects the heading component of the vehicle relative to the horizontal component of the geomagnetic force, as well as the component orthogonal to the heading, and captures data from places where the geomagnetic field is distorted, such as at railroad crossings and underground. Then, a direction detection error occurs. It is necessary to prevent data from places where the earth's magnetic field is distorted from being taken into the vehicle position detection device as azimuth detection data.

Further, when the vehicle is magnetized due to the influence of an external magnetic field, a direction detection error also occurs. Therefore, it is necessary to correct the magnetization.

FIG. 5 ASB is a diagram for explaining the magnetized state.

The traveling direction of the vehicle is 01 degrees, the radius of the geomagnetic azimuth circle is r1, the output of the geomagnetic azimuth sensor 2 is M (xi, yL), and the center coordinates of the geomagnetic azimuth circle moved by magnetization are ΔX, Δy.

The above θl, r, M(xl.

If yl) is known, ΔX and Δy can be calculated. Then, from the output M(xl,)'1) ΔX1Δy
The exact orientation (xi - Δx, yl
−Δy) can be obtained.

Therefore, the applicant attached a geomagnetic azimuth sensor and a turning angle sensor to the vehicle, calculated the heading θl based on the turning angle signal output from the turning angle sensor, and calculated the heading θl and the radius r of the geomagnetic azimuth circle. The amount of magnetization (ΔX, Δy) of the vehicle is detected based on the detected amount of magnetization (ΔX, Δy).
, Δy) (the title of the invention is "Magnetization correction method for geomagnetic direction sensor") (see Japanese Patent Laid-Open No. 169517/1983).

According to the magnetization correction method for a geomagnetic azimuth sensor, the amount of magnetization of a vehicle can be detected as long as the radius of the geomagnetic azimuth circle to be used as a reference is accurate.

However, the strength of the earth's magnetic field varies approximately in proportion to the latitude of the earth, and in Japan, the strength of the earth's magnetic field varies approximately in proportion to the latitude of the earth.
4000nT (nano tesla), approximately 2 (io
It is oonT. Therefore, if the radius of the geomagnetic azimuth circle is fixed and the magnetization correction of the geomagnetic azimuth sensor is performed based on the fixed radius of the geomagnetic azimuth circle and the moving azimuth, the magnetization correction will be accurate in a specific area. However, there is a problem in that accurate magnetization correction cannot be performed in other areas.

Furthermore, the geomagnetic declination also changes approximately in proportion to the latitude of the earth, and is approximately 5 degrees in the Okinawa region and approximately 9 degrees at Cape Soya.

Therefore, if the geomagnetic declination is fixed and the azimuth data from the geomagnetic azimuth sensor is corrected to the azimuth on the map based on the fixed geomagnetic declination, the correction can be made accurately in a specific area. However, in other areas, the geomagnetic direction and the direction on the map deviate, so there is a problem that accurate direction correction cannot be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle position detection device that enables magnetization correction and direction correction of a geomagnetic direction sensor in any region.

Means and Effects for Solving the Problems> To achieve the above object, the vehicle position detection device of the first invention has the following features: calibrating the radius of the geomagnetic azimuth circle based on the geomagnetic intensity data calculated by the geomagnetic data calculation means, and calibrating the radius of the geomagnetic azimuth circle based on the geomagnetic declination data output from the geomagnetic azimuth sensor. calibrating means for calibrating an output signal to the azimuth on the map; a turning angle detection signal detected by a turning angle sensor mounted on the vehicle; and a radius of a geomagnetic azimuth circle calibrated by the calibrating means and the output signal. and magnetization correction means for correcting the deviation of the center coordinates of the geomagnetic azimuth circle.

With the invention configured as above, the geomagnetic strength and declination of the geomagnetic field at the estimated position of the vehicle are calculated by the geomagnetic data calculation means based on a predetermined function, and the geomagnetic strength data and declination of the geomagnetic field corresponding to the estimated position of the vehicle are calculated. Obtain declination data. The calibration means calibrates the radius of the geomagnetic azimuth circle based on the geomagnetic intensity data corresponding to the estimated position of the vehicle, and output output from the geomagnetic azimuth sensor based on the geomagnetic declination data corresponding to the estimated position of the vehicle. Calibrate the signal (geomagnetic direction) to the direction on the map. The magnetization correction means detects a shift in the center coordinates of the geomagnetic azimuth circle based on the rotation angle detection signal, the calibrated radius of the geomagnetic azimuth circle, and the output signal,
Magnetization correction is performed based on this amount of deviation. Therefore, the subsequent output signal corrected by the magnetization correction means becomes accurate heading data, and is based on the calibrated and magnetized output signal of the geomagnetic direction sensor and the mileage signal from the mileage sensor. Position detection can be performed accurately.

Note that while the magnetization correction is being performed, the traveling direction data is obtained based on the turning angle detection signal output from the turning angle sensor.

In addition, the vehicle position detection device of the second invention divides a map of a predetermined range, and includes a storage means that stores the geomagnetic strength and declination of the geomagnetic field in each divided area, and updates the area as the vehicle travels. a reading means for reading the geomagnetic strength data and the geomagnetic declination data each time the reading means reads out the geomagnetic strength data, and calibrating the radius of the geomagnetic azimuth circle based on the geomagnetic strength data read by the reading means; calibrating means for calibrating the output signal output from the geomagnetic azimuth sensor to the azimuth on the map based on the rotation angle detection signal, the radius of the calibrated geomagnetic azimuth circle and the output signal; and magnetization correction means for correcting coordinate deviations.

According to the above-mentioned second invention, each time the vehicle moves and updates the district, the geomagnetic strength data and the geomagnetic declination data of the district entered are read from the storage means, so that the vehicle can start traveling anew. 0 Magnetic strength data and declination data can be obtained in the area where
It is possible to correct the magnetization of the geomagnetic azimuth sensor and detect the vehicle position in a shorter time than it takes to calculate the strength and declination of the geomagnetic field.

<Examples> Examples will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 is a block diagram showing an embodiment of the position detection device of the present invention. The position detection device includes a mileage sensor 1 that detects the distance traveled by the vehicle, a geomagnetic direction sensor 2, and a turning angle sensor 3 (for example, a wheel speed sensor that detects the turning angle based on the difference in travel distance between the two wheels, a gyro, etc.). ) and a location detection system that stores road map data that divides a road map of a predetermined range (for example, Japan Road Map) into multiple districts and approximates the roads in each divided district to the driving route of the vehicle. a map memory 4; a geomagnetic data calculation unit 5 that calculates the geomagnetic strength and declination of the geomagnetism at the current location based on a geomagnetic intensity distribution function and a geomagnetic declination distribution function; A calibration unit 6 that calibrates the radius of the azimuth circle and also calibrates the output signal of the geomagnetic azimuth sensor 2 based on the calculated geomagnetic declination data, and the geomagnetic intensity calculated by the geomagnetic data calculation unit 5 and the geomagnetic azimuth sensor 2. a selection section 7 that takes in the output signal of the geomagnetic azimuth sensor 2 as data for position detection only when the difference between the output signal and the geomagnetic strength obtained from the output signal is less than a predetermined value; a magnetization correction unit 8 that detects the amount of magnetization of the vehicle based on the detected amount of magnetization, and corrects the geomagnetic azimuth sensor 2 based on the detected amount of magnetization; and the mileage data from the mileage sensor 1 and the geomagnetic azimuth sensor. 2 or the turning angle signal from the turning angle sensor 3, and compares this driving trajectory with the road stored in the map memory 4 to determine the vehicle position on the road. It has a position detection unit 9 that calculates the position.

To explain in more detail, the geomagnetic data calculation unit 5 integrates the mileage signals from the mileage sensor 1, and calculates 1 2 when the accumulated mileage reaches a predetermined distance, and the geomagnetic intensity distribution function TI of the following equation 1. The geomagnetic strength of the current location is calculated based on the geomagnetic declination angle Δe of the current location, and the geomagnetic declination angle Δe of the current location is calculated based on the geomagnetic declination distribution function of Equation 2 below.

TH-8(1(155,6nT-40'3.04"
Δψ−T 99.43 A λ−8,213nTΔψ2+T 11.140 ΔψΔ2−4.747nTΔ22・1
Δθ−7° 5°, 45+21°, 03Δλ−〇°, 3
60Δψ2+0', 274 ΔψΔλ10", 470Δ
λ2 ...2 However, Δψ−ψ−3
7°N Δλ−λ−138°E nT is nanotesla, N is northward, E is eastward, φ is latitude, and λ is longitude.

The above geomagnetic intensity distribution function and geomagnetic declination distribution function were obtained based on experimental values, and are
Geomagnetic strength distribution in Japan based on 138° east longitude,
The geomagnetic declination distribution is approximated by a square distribution function.

The calibration unit 6 inputs the geomagnetic intensity data from the geomagnetic data calculation unit 5 and calibrates the radius of the geomagnetic azimuth circle according to equation 3 below. Then, the output M of the geomagnetic direction sensor 2
(X, Y) is taken in, and the following formula 4 is calculated to calculate the geomagnetic strength T and the geomagnetic direction e at the current location. Adding the geomagnetic declination data Δe to this direction e, the map direction (e'-
〇+Δθ).

r2- rlX [Ts2/TslF-
3 (where r2 is the radius after calibration, rl is the radius before calibration,
Ts2 is geomagnetic strength information after calibration, and Tsl is geomagnetic strength information before calibration. ) T-I M + -+Y1- e-jan -' (X/Y) ”・
4 (X is the component perpendicular to the advancing direction of the geomagnetic horizontal component, Y
is the advancing direction component of the geomagnetic horizontal component force) The selection unit 7 determines that the geomagnetic strength T calculated above is the geomagnetic strength information Ts2X.
It is determined whether or not it is within the range of (L±α), and if it is determined that it is not within the range, the output M is not taken in as data. The above α is set to a value that causes a position detection error when the output M is used as data. A suitable value for this value is about 0.1 to 0.2.

Based on the previous rotation angle signal output from the rotation angle sensor 3 and the current rotation angle detection signal, the magnetization correction unit 8
The current orientation θ1 (see Figure 4) is detected, and the amount of magnetization of the vehicle is detected based on this detected orientation and the radius of the geomagnetic azimuth circle calibrated by the calibration unit 6. Corrects the geomagnetic direction sensor based on the amount of magnetism.

Until the magnetization correction section 8 performs the correction, the position detection section 9 determines whether the vehicle is traveling based on the azimuth θ1 calculated based on the turning angle signal from the turning angle sensor 3 and the mileage signal. After the trajectory is calculated and corrected, the trajectory of the vehicle is calculated based on the accurate azimuth signal and mileage signal supplied from the magnetization correction section 8. Then, the road on which the travel trajectory is most similar to the road stored in the map memory 4 for position detection is recognized as the road on which the vehicle is traveling, and the vehicle position on this road is detected. Although the position detecting section 9 employs so-called map matching navigation, it does not include the map memory 4 for position detection and employs so-called dead reckoning navigation, and uses the turning angle signal from the turning angle sensor 3 or magnetization. It is also possible to calculate the estimated position of the vehicle based on the corrected direction signal and mileage signal.

The operation of the position detecting device will be explained based on the flowchart of FIG.

In step (2), the mileage signal from the mileage sensor 1 is integrated, and when the accumulated mileage reaches a predetermined distance, the geomagnetic strength TS2 at the current location is calculated based on the geomagnetic strength distribution function TH of the formula 1.

In step (2), the geomagnetic declination Δe at the current location is calculated based on the two geomagnetic declination distribution functions.

In step (2), the radius of the geomagnetic azimuth circle is calibrated to the radius of the geomagnetic azimuth circle at the current location according to equation 3.

In step (2), the output signal M of the geomagnetic direction sensor 2
With (X, Y) as input, Tm J] (71")2T1θ-tan -' (X/
Y) The geomagnetic strength T1 and geomagnetic direction e at the current location are calculated by the following calculation.

In step ■, eos (e+Δe), 5in
Find (e+Δe). That is, the geomagnetic direction e is calibrated to the map direction (e'-e+Δe). For example, at a certain point in Japan, the geomagnetic north is tilted 6 degrees northwest of the north of the map. In this case, change the map direction to 90 degrees + 6
degree (rotate counterclockwise).

In step (2), it is determined whether or not the calculated geomagnetic strength T is within the range of the geomagnetic strength information Ts2X (1±α), and if it is determined that it is not within the range of Ts2X (L±α), In step (2), the current position of the vehicle is calculated based on the azimuth θ1 obtained from the turning angle signal and the travel distance signal, and in step (2), magnetization correction is performed.

In step ① above, the calculated geomagnetic strength T is T
If it is determined that it is within the range of s2X (1 ± α),
In step (2), it is determined whether the difference between the map orientation e' and the orientation θ1 obtained from the turning angle signal is greater than or equal to a certain value, and if it is less than the certain value, step [phase]
In the step, the current position of the vehicle is calculated based on the map orientation e' and the travel distance signal. Note that the above-mentioned constant value includes a threshold value for selecting the output from the geomagnetic azimuth sensor 2 based on the azimuth data from the turning angle sensor 3 which is locally more accurate than the azimuth data from the geomagnetic azimuth sensor 2. It is.

If it is determined in step (2) that the difference between the map orientation e' and the orientation θl obtained from the turning angle signal is greater than or equal to a certain value, steps (2) and (2) are performed.

In addition, in step [phase], instead of map orientation θ',
For example, as shown in the formula below, the map orientation e' and the orientation θl obtained from the turning angle signal can be weighted in a predetermined manner as orientation data.

θ-(Aθ2+Bθl)/(A+B) (However, A,
B is a coefficient for weighting) According to the above embodiment, when the vehicle is magnetized, the position detection unit 9 calculates the turning angle supplied from the turning angle sensor 3. The position is detected based on the azimuth θ1, and after correction is performed, the position is detected based on the azimuth signal obtained by correcting the output of the geomagnetic azimuth sensor 2, so that it is possible to detect places where there is distortion in the geomagnetic field as in the past. Even when the vehicle is running, the azimuth signal is not lost, so accurate position detection can be performed at all times.

FIG. 3 is a block diagram showing another embodiment.

The difference from the embodiment shown in FIG. 1 above is that a reading unit 11 stores geomagnetic intensity data and geomagnetic declination data in the display map memory 10 and reads out the geomagnetic strength and geomagnetic declination from the display map memory 10. The point is that it has the following. This display map memory 10 has a format configuration as shown in FIG. 4, in which a road map of a predetermined range is divided into a plurality of districts, the code number of each divided district, geomagnetic strength data of each district, and geomagnetic polarization. The angle data is stored in the header section.

Then, in the data section, roads, main structures, rivers, etc. in each district,
It stores the coordinate positions of background data such as railways.

The operation of the position detection device of the above embodiment is as follows. That is, before starting traveling, the reading unit 11 reads the geomagnetic intensity at the current position from the map memory 10, and the calibration unit 6 can calibrate the radius of the geomagnetic azimuth circle based on the read geomagnetic intensity data. Then, after the start of travel, the position detection unit 9 detects the entry of the vehicle into a new area based on the position detection signal, and reads out a command to read geomagnetic strength data and geomagnetic declination data of the new area entered. Part 11
Output to. The reading unit 11 reads geomagnetic strength data and geomagnetic declination data of the area entered from the map memory 10,
It is supplied to the calibration section 6.

The calibration unit 6 calibrates the radius of the geomagnetic azimuth circle in correspondence with the new district based on the supplied geomagnetic strength data and geomagnetic declination data, and also calibrates the output signal of the geomagnetic azimuth sensor 2.

In the embodiment shown in Fig. 3 above, each time the vehicle moves and updates the area, the geomagnetic intensity data and geomagnetic declination data of the area it has entered are read out, and the geomagnetic direction is determined based on the read geomagnetic intensity data. By calibrating the radius of the circle, the magnetization correction of the geomagnetic azimuth sensor can be performed in a shorter time than calibrating the geomagnetic strength. In addition, by calibrating the output signal of the geomagnetic azimuth sensor 2 to the map azimuth based on the read geomagnetic declination data, the output of the geomagnetic azimuth sensor 2 can be calibrated to the map azimuth in a shorter time compared to calculating the geomagnetic declination. Can be calibrated.

<Effects of the Invention> According to the present invention, the geomagnetic intensity and the geomagnetic declination at the vehicle position are calculated, and the radius of the geomagnetic azimuth circle is calculated based on the calculated geomagnetic intensity data and the geomagnetic declination data.
By calibrating the output signal of the geomagnetic azimuth sensor to the map azimuth, it is possible to correct the magnetization of the geomagnetic azimuth sensor and accurately detect the current position no matter where the vehicle is located. A unique effect can be obtained.

In addition, the road map is divided, the geomagnetic strength of each divided area is stored in memory, and each time the vehicle moves and updates the area, the geomagnetic intensity data of the area entered is read out,
By calibrating the radius of the geomagnetic azimuth circle based on this read geomagnetic strength data, a unique effect is that the magnetization correction of the geomagnetic azimuth sensor can be performed in a shorter time compared to calculating the geomagnetic strength. can get.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the position detection device of the present invention, Fig. 2 is a flowchart of the vehicle position detection device, Fig. 3 is a block diagram showing another embodiment, and Fig. 4 is a display map. A diagram showing a format configuration of a memory. FIGS. 5A and 5B are diagrams explaining a magnetized state. 2...Geomagnetic direction sensor, 3...Turning angle sensor,
5... Geomagnetic data calculation unit, 6... Geomagnetic azimuth circle calibration unit, 10... Map memory for display, 11... Reading unit 1 2

Claims (1)

[Claims] 1. Mileage sensor, geomagnetic direction sensor, Attach a turning angle sensor to the vehicle and The output signal from the magnetic direction sensor and the rotation Turning angle signal output from turning angle sensor Obtain the appropriate heading based on the From the heading data and mileage sensor The vehicle is controlled based on the output mileage signal. Vehicle position detection device that detects estimated position Leave it behind. The geomagnetic declination of the vehicle's estimated position, and Calculate the strength of geomagnetism based on a predetermined function geomagnetic data calculation means, Calculated using the above geomagnetic data calculation method Earth's magnetic field based on geomagnetic strength data In addition to calibrating the radius of the atmospheric direction circle, Geomagnetic direction sensor based on atmospheric declination data the output signal output from the server on the map. calibration means for calibrating the The above turning angle detection signal and the calibrated The radius of the geomagnetic azimuth circle and the geomagnetic azimuth circle geomagnetic azimuth circle based on the output signal of the sensor Magnetization correction hand that corrects the deviation of the center coordinates of step by step, Vehicle position inspection characterized by having Output device. 2. Mileage sensor, geomagnetic direction sensor, Attach a turning angle sensor to the vehicle and The output signal from the magnetic direction sensor and the rotation Turning angle signal output from turning angle sensor Obtain the appropriate heading based on the From the heading data and mileage sensor The vehicle is controlled based on the output mileage signal. Vehicle position detection device that detects estimated position Leave it behind. Divide the map of a predetermined range, and each divided Geomagnetic strength and declination of the area a memory means that memorizes the The ground is updated each time the vehicle travels and updates the area. Magnetic strength data and geomagnetic declination data reading means for reading the data; The geomagnetic strength data read by the reading means Calibrate the radius of the geomagnetic azimuth circle based on the data At the same time, read out the geomagnetic declination data. output from the geomagnetic direction sensor based on Calibrate the output signal to the orientation on the map calibration means; The above turning angle detection signal and the calibrated The radius of the geomagnetic azimuth circle and the output signal Based on the deviation of the center coordinates of the geomagnetic azimuth circle a magnetization correction means for correction; Vehicle position inspection characterized by having Output device.