JP3277778B2 - Direction detection device - Google Patents

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 for navigation, for example.

[0002]

2. Description of the Related Art Conventionally, a magnetic sensor such as a flux gate is provided to obtain an azimuth signal to a navigation display or the like mounted on a moving body such as an automobile so that the traveling direction can be grasped in comparison with the azimuth. , And measures the magnetic field vector of the running area.

Since the azimuth detecting device including such a magnetic sensor is affected by the magnetization specific to the vehicle body of the vehicle in which the azimuth sensor is mounted, the detection output is corrected to eliminate the influence of the magnetization specific to the vehicle body. The magnetic field vector is obtained. For example, Japanese Patent Publication No. Sho 62-30364,
As proposed in Japanese Patent No. 14125, the center of a circular vector obtained by the rotation of a car is obtained, and the center coordinate is subtracted from the detected coordinates to correct the error due to the body-specific magnetization. I have.

Such an error correction method by calculating the center of a circular vector has the 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 azimuth detection. Affects the simplification of the calculation step.

[0005]

In such a correction method, in the above-mentioned conventional configuration, a method of detecting four points intersecting the X-axis and the Y-axis on the coordinates of the circular vector and obtaining the center from the four points. However, in the former method, Xmin, Xmax, Ymin, and Ymax must be sequentially calculated and calculated during the measurement of the circular vector. The deviation of the measurement points causes the measurement points to jump, and particularly when the vehicle turns 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 X-intersection calculation steps are required to prepare predetermined X-axis lines and Y-axis lines, obtain intersection coordinates of these axes and circular vectors, and calculate the center from the coordinates of the four points thus obtained. The calculation data is calculated by taking in these four points, so that the processing becomes complicated.

In each of the detection methods, the center of the detected coordinate data is obtained. For example, a signal generated by the influence of disturbance magnetism other than the normal geomagnetism or the influence of electric noise is used as a normal detection signal. Since the center point is calculated based on the input data, the center point becomes extremely large when the detection points due to such noises are approaching, and cannot be used for azimuth detection. Would.

SUMMARY OF THE INVENTION It is an object of the present invention to judge erroneous detection data due to noise or the like and to perform accurate azimuth detection without using it as data for calculating a center. Further, the center of the circular vector is obtained by a simple arithmetic processing. It is another object of the present invention to provide an azimuth detecting device which can obtain a calculation load, thereby reducing a calculation load and simplifying the configuration.

[0008]

SUMMARY OF THE INVENTION The present invention receives a detection signal corresponding to geomagnetism having a phase angle of about 90 degrees on the same plane from a magnetic sensor, detects an azimuth based on this signal, A control unit for correcting a variation error from terrestrial magnetism due to a magnetization characteristic inherent to a moving body on which the magnetic sensor is mounted by correcting a center point from a circular vector obtained by rotation of the magnetic sensor; X is based on coordinate data corresponding to at least three detected coordinates having one coordinate in common on the circular vector.
The center of the other coordinate data of the coordinate and the Y coordinate is obtained, and the coordinate data center calculation processing is performed only when the absolute value of the difference between the other coordinate data exceeds an arbitrary fixed value R (an arbitrary radius of a circular vector). And correcting the fluctuation error by subtracting the center data from each data of the detected coordinates (X, Y) on the circular vector.

Further, the present invention receives an output signal from a magnetic sensor which outputs a detection signal corresponding to terrestrial magnetism having a phase angle of about 90 degrees on the same plane from the magnetic sensor, and determines an azimuth based on this signal. Control means for detecting and correcting a variation error from terrestrial magnetism due to a magnetization characteristic inherent to a moving body on which the magnetic sensor is mounted by correcting a center point from a circular vector obtained by rotation of the magnetic sensor. The control means controls the other two points (X1, Y2) on the circular vector, which share an arbitrary starting point (X1, Y1) on the circular vector and one of the starting point coordinates.
Based on the data of (X2, Y1) and (X2, Y1), the center of the circular vector is obtained by (X1 + X2) / 2 and (Y1 + Y2) / 2, and from the data of the detected coordinates (X, Y) on the circular vector, By subtracting the center data, the fluctuation error is corrected, and | X1-X2 |> = R, | Y
It is characterized in that it is determined whether or not at least one condition of 1−Y2 |> = R (R is a fixed value of the radius of the circular vector) is satisfied, and when the condition is satisfied, the center correction of the circular vector is performed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION For a circular vector corresponding to geomagnetism obtained by rotating a magnetic sensor, whether or not the absolute value of the difference between detected and inputted coordinate data exceeds a value R corresponding to an arbitrary radius It is possible to provide an azimuth detecting device capable of preventing erroneous detection due to noise or the like and determining an accurate calculation result in azimuth detection.

In addition, a circular vector corresponding to terrestrial magnetism obtained by rotating the magnetic sensor has an arbitrary starting point (X
1, Y1) and the other two points that share the coordinates of one of the start point coordinates, (X1, Y2) and (X2, Y1), and define the center of the circular vector as (X1 + X2), (Y1,
Y2), and a control means for subtracting the center data from each coordinate data of the detected coordinates (X, Y) to correct the error is provided, so that the calculation based on a small number of detected point data becomes possible, and the starting point is further reduced. It is possible to provide an inexpensive device by reducing the calculation load on the control means while having a determination function for preventing erroneous detection due to noise or the like in the vicinity.

[0011]

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

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

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

In the present invention, the control means 9 corrects the output signal of the A / D converter 8 including an error due to the magnetizing characteristics inherent to the vehicle and obtains a faithful azimuth by geomagnetism. As for 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 is turned around on the spot in the traveling area, the mounted magnetic sensor 1 is also rotated in the geomagnetic field in the area and outputs a coordinate output corresponding to the geomagnetism. However, the detection output characteristic based on only the true geomagnetism which is not affected by the magnetization characteristics of the vehicle can be obtained as a circular vector locus centered on the origin coordinate O, whereas the magnetization characteristic unique to the vehicle is not sufficient. Since the detection component is added as an error to the detection component, the detection output is largely shifted from the center of the circular vector as shown in FIG. 2. For example, a circular vector output centered on the coordinate (X0, Y0) is sent to the control means 9. Is entered.

The control means 9 first determines an operation start point in the circular vector output data (X, Y) shown in FIG. 2. The operation start point is obtained by adopting a turn start initial value when turning the vehicle. Good. For example, the turning start initial value issues a correction value determination command to the control means 9 at the time of a turning operation for determining a correction value, and the initial input value of a detection signal fetching operation for a correction value determination calculation process based on this command is a starting point ( X1, Y1). As for the execution of the correction value determination calculation process, for example, a switch operable by the driver is prepared in advance, and the control means 9 can perform the correction value calculation by operating this switch. After that, the magnetic sensor 1
Correction calculation based on this correction value is performed on the detection output including the error in the above, and the correct azimuth data corresponding to the geomagnetism can be obtained and output. The azimuth display device can also display the azimuth using the 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 being a as shown in FIG.
In this case, the detection output (X, Y) obtained when the vehicle is turned around from the starting point is obtained as a circular vector centered on the center (X0, Y0). The other two points (X1, Y2) and (X2, Y1) which share the coordinates of one of the starting point (X1, Y1) and one of the coordinates are selected, and the center coordinates of the circular vector are determined based on these data, respectively. X0 = (X1 + X2) / 2, Y0 = (Y1 + Y2)
/ 2.

In this way, the center of the circular vector (X0, Y0) can be easily determined only by the coordinate data of the starting point (X1, Y1) and the other two points (X1, Y2) and (X2, Y1). After that, the detection data (X, Y)
By subtracting the center data (X0, Y0), which is the correction value from the above, it is possible to obtain azimuth data faithful to geomagnetism in which errors due to the magnetization characteristics unique to the vehicle have been corrected. That is, assuming that the azimuth data is (XM, YM), the azimuth correction calculation in the control means 9 becomes XM = X−
(X1 + X2) / 2, YM = Y- (Y1 + Y2) / 2.

The azimuth data corresponding to the geomagnetism obtained in this way 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 running area of the automobile. The detection and calculation of the coordinates of three points by the detection device of the present invention are represented by the calculation of the start point in the circular vector locus shown in FIG. 2 and the selection of the other two points. Is the same as the center coordinate X0 or Y0 of the circular vector as shown in FIG. 3, the coordinates (X1, Y1) are obtained as the starting point (X0, Y1). 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.

Accordingly, the calculation itself of the X coordinate such as XM = X- (X1 + X2) / 2 is not required, and the calculation step is further simplified. Therefore, taking advantage of such a feature, the starting point of at least one of the coordinates is previously set to this coordinate. A similar calculation can be reduced by selection. That is, the MIN coordinate or MAX of the circular vector is obtained 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 subsequent detection points can be reduced, and the number of calculation steps including the correction value can be reduced.

In the present invention, an arbitrary starting point (X
, Y1), and the other two points (X1, Y2), (X
In detecting (2, Y1), in order to prevent a large error when these two points pick up disturbance magnetic or electric noise other than geomagnetism near the starting point and detect them, prior to the circular vector center calculation and correction calculation. Then, a determination process is performed to determine whether or not the detected data can be used to correctly determine the center of the circular vector.

That is, immediately after the starting point (X1, Y1) is determined and the vehicle starts to turn, that is, near the starting point, the other two points (X1, Y1) due to disturbance magnetism and electric noise other than geomagnetism.
2), (X2, Y1), as shown in FIG.
If a point is detected and the center point is obtained by calculation as it is, (X0 ', Y0') in the figure is recognized as the center point, and an error is generated with respect to the center point (X0, Y0) which is truly obtained.

An error due to such erroneous detection can be tolerated as a slight error from a normal dashed locus at a position distant from the start point, but such a noise error near the start point immediately after the start of detection (start of turning). Is extremely large when it is used as data for obtaining a center point which is a point on a circular vector trajectory as shown in the figure, and is almost useless as data for correction.

Therefore, in the present invention, such a starting point (X
(1, Y1) It is determined whether or not the data is erroneously detected near the start point, and when it is determined that the data is near the start point, the center of the circular vector is not obtained, and the azimuth detection based on the erroneous center data is not performed. Has functions.

That is, in the control means 9, the starting point (X1,
Immediately after detecting (Y1), if (X1, Y2) and (X2, Y1) shown in FIG. 4 are detected as other two points due to noise or the like, first, | X1-X2 |> = R, | Y1-Y2 |
> = R, and when either one is satisfied, (X1 + X2) / 2, (Y1 +
Y2) / 2 is performed to determine the center of the circular vector, and to perform a calculation to correct the fluctuation error by subtracting the center data from each data of the detected coordinates (X, Y). The radius R at this time may be set arbitrarily by approximating the radius of a circle corresponding to a circular vector obtained by the turning locus of the vehicle.

With such a determination function, as shown in FIG. 4, a detection input due to noise or the like occurs near the starting point, and when this is input as (X1, Y2), (X2, Y1), | X1-X2 | and | Y1-Y2 | are determined to be smaller than the set radius R, and the process does not proceed to the subsequent vector center calculation operation. It is possible to obtain only a simple calculation result.

In the above embodiment, the center detection based on the coordinates of three points with the other two points having the common start point (X1, Y1) has been described. However, erroneous detection due to noise or the like is prevented to obtain correct detection data. For this purpose, the detection determination function based on the magnitude determination of the absolute value of the coordinate difference with respect to the value R corresponding to an arbitrary radius is not particularly limited to such three-point detection, but finds the center of the coordinates of two points on a circular vector. It goes without saying that the present invention can be applied to any configuration as long as the method is adopted.

[0028]

As described above, according to the azimuth detecting device according to the present invention, even if abnormal data due to noise or the like is input to the detection data on the circular vector obtained by turning the vehicle, it can be easily detected. To prevent the data from being adopted as erroneous detection data and to obtain an accurate azimuth. Further, the starting point coordinates and one of the other two coordinates are compared and matched to obtain a center coordinate which is a correction value. Since it only needs to be executed in simple operation steps, even when the control means is constituted by a microcomputer, the number of the operation processes can be reduced,
It is possible to simplify peripheral circuits and reduce costs by lowering the clock frequency and reducing current consumption by using a low bit processor.

[0029]

[Brief description of the drawings]

FIG. 1 is a typical circuit block diagram of an azimuth detecting device to which the present invention is applied.

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

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

FIG. 4 is an explanatory view of detection output for explaining erroneous detection due to noise or the like in the azimuth detecting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic sensor 2 Annular core 5, 6 Output winding 8 A / D converter 9 Control means 10 Display device

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01C 17/38 G01R 33/02 G01R 33/04

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the position of the magnetic sensor is approximately 90
Receiving a detection signal corresponding to terrestrial magnetism having a phase angle of degrees, detecting an azimuth based on this signal, and detecting a variation error from terrestrial magnetism due to a magnetization characteristic inherent to a moving body on which the magnetic sensor is mounted. Control means for correcting by a center point correction from a circular vector obtained by the rotation of the circular vector, the control means corresponding to at least three detected coordinates having one coordinate in common on the circular vector. When the center of the other coordinate data of the X coordinate and the Y coordinate is obtained based on the coordinate data to be calculated, and the absolute value of the difference between the other coordinate data exceeds an arbitrary fixed value R (an arbitrary radius of a circular vector) Correcting the fluctuation error by executing the coordinate data center calculation process and subtracting the center data from each data of the detected coordinates (X, Y) on the circular vector. Azimuth detecting device according to claim. 2. On the same plane from the magnetic sensor, approximately 90
Receiving a detection signal corresponding to terrestrial magnetism having a phase angle of degrees, detecting an azimuth based on this signal, and detecting a variation error from terrestrial magnetism due to a magnetization characteristic inherent to a moving body on which the magnetic sensor is mounted. Control means for correcting the center point from a circular vector obtained by the rotation of the circular vector. The control means includes an arbitrary starting point (X1, Y1) and one of the starting point coordinates on the circular vector. , Two other points on a circular vector that share the coordinates of (X1, Y
Based on the data of (2) and (X2, Y1), the center of the circular vector is set to (X1 + X2) / 2 and (Y1 + Y2) /
2 and the detected coordinates (X,
The variation error is corrected by subtracting the center data from each data of Y), and the start point (X1, Y
In performing the center correction of the circular vector based on the data of 1) and the other two points (X1, Y2), (X2, Y1), |
It is determined whether or not at least one condition of X1-X2 |> = R or | Y1-Y2 |> = R (R is a fixed value of a circular vector radius) is satisfied, and if so, the circular vector is determined. A azimuth detecting device, which performs a calculation of a center point and a correction.