JPS6385312A - Vehicle azimuth measuring apparatus - Google Patents

Abstract

PURPOSE:To suppress the error in azimuth data due to disturbance, by comparing the azimuth data obtained by a pair of the earth magnetism sensor mounted on a vehicle at a definite distance from each other, and estimating and interpolating the azimuth data on the basis of the comparing error output obtained. CONSTITUTION:The azimuth detection outputs obtained by a pair of the earth magnetism sensors 12, 13 mounted on a vehicle at a distance from each other are inputted to a gain offset control circuit 14, and a gain and offset are adjusted to the same ratio. The individual azimuth detection outputs adjusted are separately inputted to AD converters 15, 15'. The magnitudes of the azimuth data D12, D13 obtained from said AD converts 15, 15' are compared by a comparator 17 and, when comparing error output D12-D13 exceeds a predetermined set value, it is judged that there is the effect of disturbance and the azimuth data during a time receiving the effect of disturbance is estimated from the azimuth data before and after said data to be interpolated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle position measuring device that reliably eliminates disturbances to a geomagnetic sensor.

[Prior Art] A vehicle direction measuring device 1 shown in FIG. 4 measures the direction of a vehicle using a geomagnetic sensor 2, and is incorporated into an on-vehicle navigation device that estimates the current location of the vehicle based on distance data and direction data. ing. The geomagnetic sensor 2 has a pair of wire rings 4x and 4y wound in a cross shape so as to straddle the outer diameter of an annular yoke 3, and an excitation winding 5 wound annularly around the yoke 3 is connected to a drive circuit 6. The structure is such that an alternating current magnetic field serving as a bias is induced by energizing and excitation. If you know the voltages Ex and By induced in the wire rings 4x and 4y by the north-south and east-west components of the geomagnetic horizontal component, use the ratio Ex / Ey to calculate j a n -
' Since the vehicle direction θ can be calculated from (E x / E y ), the output AC voltage Ex of both wheels 4x and 4y is
Ey is supplied to a synchronous rectifier circuit 7 connected to the drive circuit 6, and a frequency component twice the drive voltage is extracted and used as a DC voltage for calculation by an arctangent calculation circuit 8.

[Problems to be Solved by the Invention] The conventional vehicle direction measuring device I described above uses a geomagnetic sensor when the vehicle crosses a railroad crossing, passes under an elevated wire, or passes by a power transmission line. 2 is affected by a strong electromagnetic field, the outputs Ex, Ey of wire rings 4x, 4y
Since disturbances unrelated to the earth's magnetic field are mixed into the system, accurate direction measurement cannot be performed, leading to problems such as errors in estimating the vehicle's current location.

In addition, in order to suppress the influence of this type of disturbance as much as possible, a vehicle direction measurement device has been proposed that dilutes the influence of disturbance by averaging several pieces of azimuth data obtained in the past. If it exceeds the normal level,
The dilution effect of averaging may have little effect, and if the vehicle changes course frequently within a short period of time, the fluctuations in the heading data due to the course changes will be averaged out, which may actually be There were problems such as the possibility of having the opposite effect.

[Means for Solving the Problems] This invention solves the above problems, and includes a pair of geomagnetic sensors that are mounted on a vehicle at a certain distance from each other and detect the direction of the vehicle based on the geomagnetic field. , a comparator that compares the orientation obtained by both geomagnetic sensors, and if the comparison error output of this comparator exceeds a predetermined range, it is determined that there is an influence of disturbance, and the orientation data during that time is The present invention is characterized by comprising an estimation complementing means for estimating and complementing the azimuth data before and after the received direction data.

[Operation] This invention compares azimuth data obtained by a pair of geomagnetic sensors mounted on a vehicle at a certain distance from each other,
If the comparison error output exceeds a predetermined range, it is determined that there is a disturbance, and the azimuth data during that period is estimated and complemented from the azimuth data before and after the disturbance.
Minimize deviations in orientation data due to external disturbances.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. 1.2 is a circuit configuration diagram showing one embodiment of the vehicle direction measuring device of the present invention, and a diagram showing the relationship between a vehicle equipped with this vehicle direction measuring device and a disturbance source, and FIG. FIG. 2 is a flowchart for explaining the estimation complementing operation of the arithmetic processing device shown in FIG. 1. FIG.

In FIG. 1, a vehicle direction measuring device 11 includes a pair of geomagnetic sensors 12 and 13 that are mounted on a vehicle at a certain distance from each other and detect the direction of the vehicle based on the geomagnetic field. The gain and offset are adjusted to the same rate in preparation for AD conversion.
The individual azimuth detection outputs adjusted by the offset adjustment circuit 14 and the gain/offset adjustment circuit 14 are separately AD
A pair of AD converters 15 and 16 to convert, and these AD
Orientation data obtained from converters 15 and 16 DI2+
A comparator 17 that compares the magnitude of D I3 and this comparator 17
If the comparison error output D+1D13 exceeds a predetermined reference value De, it is determined that there is an influence of disturbance, and estimation complementation is performed to estimate and complement the azimuth data while being affected by the disturbance from the azimuth data before and after the disturbance. It roughly consists of means, etc. In the case of this embodiment, the disturbance detector 18 to which the comparison error output of the comparator 17 is supplied, the storage circuit 19 that stores the azimuth data D, , D, obtained from the AD converters 15 and 16, and the arithmetic processing The circuit 2o constitutes estimation complementing means. In addition to estimating and complementing the direction data, the arithmetic processing circuit 2o has the main task of estimating the driving route based on the distance data and the direction data, and the estimated driving path of the vehicle is
The current location is displayed on the display device 21 inside the vehicle. Incidentally, as the geomagnetic sensors 12 and 13, flux gate type ones are used like the conventional geomagnetic sensor 2.

Suppose now that a vehicle passes near the disturbance source 22 along the route shown in FIG. In this case, since the influence of the disturbance source 22 on the geomagnetic sensor 12.13 is inversely proportional to the square of the distance between the disturbance source 22 and the vehicle, it is assumed that the area indicated by the satin pattern corresponds to the dangerous area. In this case, the direction detection output of the geomagnetic sensors 12 and 13 mounted on the vehicle is
The difference will be shown during the period when the vehicle is passing through section AB. That is, before the leading end of the vehicle enters section AB, the error between the azimuth data D, , D, and 3 is detected by the disturbance detection circuit 1.
Since the data does not exceed the reference value De set in 8, it is recognized as correct data and is used in the calculation process for estimating the travel route in the final step (105) after passing through steps (101) to (104) shown in FIG. be done.

However, when the tip of the vehicle passes point A and enters section AB, the error Dll D+s between the azimuth data exceeds the reference value De set in the disturbance detection circuit 18, and as a result, the occurrence of disturbance is indicated in step (106). A flag is raised. Since this state continues until the vehicle finishes passing through section AH, the azimuth data obtained from the next time is excluded as being affected by the disturbance. The azimuth data during this period is estimated and complemented in steps (107) and (108), but in this embodiment, the azimuth data Da obtained just before the vehicle enters section AB and the azimuth data Da obtained just before the vehicle enters section AB are used. The azimuth data Db immediately after the completion of the process is read out from the storage circuit 19, and intermediate azimuth data is complemented by interpolation based on these azimuth data Da and Db. In other words, if the number of samplings performed during traveling section AB is n, the azimuth data for the first time is interpolated by using Da+ ((Db-Da)k/(n+1)). be. When the interpolation is completed in this way, the flag is returned to its original state in step (109), and normal arithmetic processing is resumed.

In this way, the vehicle position measuring device 11 includes a pair of geomagnetic sensors 12 mounted on the vehicle at a certain distance from each other,
Orientation data D obtained from 13.

Compare DI3 and output the comparison error DI2- DI
3 exceeds a predetermined reference value De, it is determined that there is an influence of disturbance, so the geomagnetic sensor 12
．． 13 is affected by disturbances caused by strong magnetic field sources such as railroad crossings, elevated lines, or power transmission lines, clearly distinguishes between data affected by the disturbance and data not affected by the disturbance, and reliably eliminates unnecessary data. can do. In addition, the azimuth data during the period of disturbance is the data Da before and after the disturbance.
Since the estimation is complemented by interpolation from , Db, the chances of erroneous correction can be greatly reduced compared to, for example, a method of always obtaining azimuth data as the average value of the azimuth data of the past several times regardless of the presence or absence of disturbance. As a result, it is possible to minimize errors in azimuth data that are essential for estimating the vehicle's azimuth, and to further improve the navigation accuracy of an on-vehicle navigation system.

[Effects of the Invention] As explained above, the present invention compares azimuth data obtained from a pair of geomagnetic sensors mounted on a vehicle at a certain distance from each other, and determines whether the comparison error output exceeds a predetermined range. If the geomagnetic sensor is affected by a disturbance from a strong magnetic field source such as an elevated line or a power transmission line, the data will be determined to be affected by the disturbance. It is possible to clearly distinguish data from other data and reliably eliminate unnecessary data.
Furthermore, the azimuth data during the period of disturbance is estimated and complemented by interpolation from the data before and after the disturbance, so for example, regardless of the presence or absence of a disturbance, the azimuth data is always the average of the past several azimuth data. Compared to the method of obtaining it as a value,
It is possible to significantly reduce the chances of erroneous correction, thereby minimizing errors in the direction data that is essential for estimating the vehicle's direction, and further improving the navigation accuracy of on-vehicle navigation devices. It has a great effect.

[Brief explanation of the drawing]

1.2 is a circuit configuration diagram showing an embodiment of the vehicle direction measuring device of the present invention, and a diagram showing the relationship between a vehicle equipped with this vehicle direction measuring device and a disturbance source, and FIG.
A flowchart for explaining the estimation complementing operation of the arithmetic processing device shown in FIG. 1, and FIG. 4 is a schematic configuration diagram showing an example of a conventional vehicle direction measuring device. 11. Vehicle position measuring device, 12,13. ,. Geomagnetic sensor, 17. ,,Comparator,18. ,,disturbance detection circuit,19. ,,memory circuit,20. , arithmetic processing circuit.

Claims (1)

[Claims] A pair of geomagnetic sensors that are mounted on a vehicle at a certain distance from each other and detect the vehicle's direction based on geomagnetism, a comparator that compares the direction obtained by both geomagnetic sensors, and a comparison error output of this comparator that is A vehicle direction measurement device comprising an estimation complementing means that determines that there is an influence of a disturbance when it exceeds a predetermined certain range, and estimates and complements direction data during that period from direction data before and after being affected by the disturbance.