JPH0968432A - Bearing detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bearing detection apparatus in which a computing operation based on data on the small number of detection points can be performed and by which the computing load of a control means is reduced by a method wherein data on the center is subtracted from respective data on detection coordinates on a circular vector obtained by the rotation of a magnetic sensor. SOLUTION: An exciting signal from an oscillator 4 is given to an exciting coil 3 which has been wound on a ring-shaped core 2 for a magnetic sensor 1, and output signals having a pulse angle of about 90 deg. corresponding to terrestrial magnetism are obtained from output windings 5, 6. The output signals are inputted to a control means 9 via an amplifier circuit 7 and an A/D converter 8. In the control means 9, a change error from terrestrial magnetism due to a magnetization characteristic peculiar to a moving body on which the sensor 1 is carried is corrected by the correction of the central point of a circular vector obtained by the rotation of the sensor 1. That is to say, the center of the circular vector is found on the basis of an arbitrary starting point (X1, Y1) on the circular vector and on basis of two other points (X1, Y1), (X2, Y2) which use the coordinates, on one side, of the coordinates of the starting point in common. Data on the center is subtracted from respective data on detection coordinates, and an error is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth detecting device which is mounted on an automobile or the like to detect a traveling azimuth and can be used in, for example, navigation.

[0002]

2. Description of the Related Art Conventionally, a magnetic sensor such as a flux gate has been provided in order to obtain a direction signal to a navigation display or the like which is mounted on a moving body such as an automobile so that the traveling direction can be grasped by comparing with the direction. , I try to measure the magnetic field vector in the driving area.

In the azimuth detecting device composed of such a magnetic sensor, since it is affected by the magnetization peculiar to the vehicle body of the automobile in which it is mounted, the detection output is corrected to eliminate the magnetization effect peculiar to the vehicle body. A magnetic field vector is obtained, for example, Japanese Patent Publication No. 62-30364 and Japanese Patent Publication No. 3-.
As proposed in No. 14125, the center of a circular vector obtained by the rotation of the automobile is obtained, and the center coordinates are subtracted from the detected coordinates to correct the error due to the magnetization unique to the vehicle body. There is.

The error correction method by calculating the center of the circular vector has an advantage that the magnetic sensor can be used as it is by a simple method by calculation, and the method of calculating the center from the circular vector directly determines the accuracy of direction detection. Affects simplification of calculation steps.

[0005]

In such a correction method, in the above-described conventional method, four points intersecting on the X-axis and Y-axis on the coordinates of the circular vector are detected, and the center is obtained from these four points. However, in the former case, Xmin, Xmax, Ymin, and Ymax must be successively calculated during the measurement of the circular vector, and the turning locus in the turning motion of the vehicle for obtaining the circular vector must be obtained. The measurement points become discontinuous due to the deviation of, and particularly when turning at high speed, high speed is required to follow such measurement fluctuations, and a high-performance microcomputer is required, which is expensive. Also in the latter case, four predetermined X-axis lines and Y-axis lines are prepared, the coordinates of the intersections of these axes and the circular vector are calculated, and the center is calculated from the coordinates of the four points thus calculated. The calculation data is also calculated by taking in these four points, which complicates the processing.

[0006]

SUMMARY OF THE INVENTION The present invention provides a detection device capable of obtaining the circular vector center by a simple arithmetic process, and has phase angles of approximately 90 degrees with each other on the same plane. It receives an output signal from a magnetic sensor that outputs a detection signal corresponding to the earth's magnetism, detects the azimuth based on this signal, and eliminates fluctuation errors from the earth's magnetism due to the magnetization characteristics peculiar to the moving body on which the magnetic sensor is mounted. A control means for correcting by a center point correction from a circular vector obtained by the rotation of the magnetic sensor is provided, and the control means has an arbitrary starting point (X1, Y1) and the starting point coordinates on the circular vector. Based on the data of (X1, Y2) and (X2, Y1), the other two points on the circular vector having the coordinates of one of the two in common (X1 + X).
2) / 2 and (Y1 + Y2) / 2, and the variation error is corrected by subtracting the central data from each data of the detected coordinates (X, Y) on the circular vector, Further, the starting point is selected so that the coordinates of one of the other two points (X1, Y2) and (X2, Y1) with respect to the arbitrary starting point (X1, Y1) are the same as the starting point coordinates. And

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION For a circular vector corresponding to the geomagnetism obtained by rotating a magnetic sensor, an arbitrary starting point (X
1, Y1) and the other two points that share one of the starting point coordinates, (X1, Y2) and (X2, Y1), and the circular vector center is (X1 + X2), (Y1,
Y2) is provided and a control means for correcting the error by subtracting the center data from each coordinate data of the detected coordinates (X, Y) is provided, whereby calculation based on a small amount of detection point data becomes possible, and the control means It is possible to provide an inexpensive device by reducing the calculation load of.

[0008]

FIG. 1 is a block diagram of a typical apparatus applied to the present invention. A so-called flux gate type magnetic sensor 1 is used, and an oscillator 4 is provided in an excitation coil 3 wound around an annular core 2. From the output windings 5 and 6 wound substantially orthogonal to the annular core to obtain an output signal having a phase angle of about 90 degrees corresponding to the earth's magnetism.

An output signal from the magnetic sensor 1 is input to a control means 9 composed of a microcomputer via a signal amplification circuit 7 including a noise filter and an A / D converter 8 for converting it into a digital signal for digital processing. Then, the azimuth signal arithmetically processed by the control means 9 is supplied to the display device 10 used for navigation, for example.

Such an azimuth detecting device is mounted together with the magnetic sensor 1 on a moving body such as an automobile which is easily magnetized, and detects the geomagnetism at the traveling point of the automobile as this moving body to calculate and display the azimuth. However, since the output signal of the magnetic sensor 1 includes an error due to the magnetization characteristic peculiar to the mounted vehicle, the control means 9 performs an operation to correct this error.

In the present invention, the control means 9 corrects the output signal of the A / D converter 8 containing an error due to the magnetizing characteristic peculiar to the automobile to obtain a faithful azimuth based on the earth's magnetism. Regarding the method, the execution programming of the control means 9 is set so as to execute the typical vector detection shown in FIG.

That is, when the vehicle turns in the traveling area for traveling in the traveling area, the mounted magnetic sensor 1 also rotates in the magnetic field of the geomagnetic field in the area and outputs the coordinate output corresponding to the geomagnetic field. However, while the detection output characteristic only by the true geomagnetism, which is not affected by the magnetizing characteristic of the vehicle, is obtained as a circular vector locus with the origin coordinate O as the center, the characteristic characteristic of the vehicle is Since an error is added to the detected component, the detected output is largely deviated from the center of the circular vector as shown in FIG. 2, and the circular vector output centered on the coordinates (X0, Y0) is sent to the control means 9. Is entered.

The control means 9 first determines the calculation start point in the circular vector output data (X, Y) of FIG. 2, and the calculation start point is set to the initial value of the start of turning when the vehicle turns. Good. The initial value of the turning start is, for example, a correction value determination command is issued to the control means 9 during the turning operation for determining the correction value, and the first input value of the detection signal fetching operation for the correction value determination calculation process based on this command is set as the starting point ( X1, Y1). Regarding the execution of the correction value determination calculation process, for example, a switch operable by the driver may be prepared in advance, and the control means 9 may perform the correction value calculation by operating this switch. After that, magnetic sensor 1
Corrected azimuth data corresponding to geomagnetism can be obtained and output by executing a correction calculation based on this correction value for the detection output including the error in azimuth, and the azimuth display device can also display the azimuth according to this correct azimuth data. Becomes

In the process of determining the correction value, that is, the center coordinates (X0, Y0) of the circular vector, the coordinates of a with the starting point a as shown in FIG. 2 are the starting points (X1, Y1).
Then, the detection output (X, Y) when the vehicle is turned with this as the starting point is obtained as a circular vector centered on the center (X0, Y0), and The other two points (X1, Y2), (X2, Y1) that have one coordinate in common with the starting point (X1, Y1) are selected, and the center coordinates of the circular vector are respectively calculated based on these data. X0 = (X1 + X2) / 2, Y0 = (Y1 + Y2)
/ 2 is obtained.

In this manner, the circular vector center (X0, Y0) can be easily defined only by the coordinate data of the starting point (X1, Y1) and the other two points (X1, Y2), (X2, Y1). Since it can be obtained, the detection data (X, Y)
By subtracting the center data (X0, Y0), which is the correction value, from, it is possible to obtain the azimuth data faithful to the geomagnetism in which the error due to the magnetization characteristic of the automobile is corrected. That is, if the azimuth data is (XM, YM), the azimuth correction calculation in the control means 9 is XM = X− for each coordinate.
It is executed by (X1 + X2) / 2, YM = Y- (Y1 + Y2) / 2.

The azimuth data corresponding to the geomagnetism thus obtained is output to, for example, the display device 10 in FIG. 1 so that the traveling direction can be correctly displayed with respect to the azimuth of the traveling area of the automobile. The coordinate detection and calculation of three points by the detection device of the present invention is represented by the calculation processing by determining the starting point and selecting the other two points in the circular vector locus shown in FIG. When is coincident with the center coordinate X0 or Y0 of the circular vector as shown in FIG. 3, that coordinate (X1, Y1) is obtained as the starting point (X0, Y1), so that among the other two points ( The coordinates corresponding to (X2, Y1) are common coordinates (X0, Y
1), and in this case, the center of the X coordinate is immediately obtained by setting X1 = X0.

Therefore, the calculation itself of the X coordinate such as XM = X- (X1 + X2) / 2 becomes unnecessary, and the calculation step becomes simpler. Therefore, the starting point of at least one of the coordinates is set to this coordinate in advance by utilizing such characteristics. The same calculation can be reduced by selecting the same. That is, the MIN coordinates of the circular vector or MAX from the detection signal taken from the magnetic sensor 1 in the correction value determination process.
By detecting the coordinates and determining the coordinates as the starting point a, the number of detection points thereafter can be reduced, and the calculation step including the correction value can be reduced.

[0018]

As described above, according to the azimuth detecting apparatus of the present invention, it is only necessary to compare the starting point coordinates with the axis coordinates of one of the coordinates of the other two points to obtain the central coordinates as the correction value. Since it is only necessary to execute in simple operation steps, even when the control means is composed of a microcomputer, the number of times of the operation processing is small, and it is possible to reduce the current consumption by lowering the clock frequency and using a low bit processor. The peripheral circuits can be simplified and the price can be reduced.

[0019]

[Brief description of drawings]

FIG. 1 is a typical circuit block diagram of a direction detection device to which the present invention is applied.

FIG. 2 is an explanatory diagram of a detection output for calculating a correction value in the azimuth detecting device of the present invention.

FIG. 3 is a detection output explanatory diagram showing another embodiment of the detection output in the azimuth detecting device of the present invention.

[Explanation of symbols]

 1 magnetic sensor 2 annular core 5, 6 output winding 8 A / D converter 9 control means 10 display device

Claims (2)

[Claims] 1. An output signal from a magnetic sensor that outputs detection signals corresponding to geomagnetism having phase angles of approximately 90 degrees with each other on the same plane, receives an output signal based on this signal, and detects the azimuth based on the output signal. A control means is provided for correcting a variation error from the geomagnetism due to the magnetizing characteristic peculiar to the moving body on which the sensor is mounted by correcting the center point from a circular vector obtained by the rotation of the magnetic sensor, and the control means An arbitrary starting point (X1, Y1) on the circular vector and the other two points on the circular vector (X1, Y2) and (X2, Y1) that share one of the starting point coordinates Based on the data of
2) / 2 and (Y1 + Y2) / 2, and the variation error is corrected by subtracting the central data from each data of the detected coordinates (X, Y) on the circular vector. Direction detection device. 2. The starting point is selected so that the coordinates of one of the other two points (X1, Y2) and (X2, Y1) with respect to the arbitrary starting point (X1, Y1) are the same as the starting point coordinates. The azimuth detecting device according to claim 1, wherein