JPH09126781A - Azimuth detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a detection error due to noise and the like when an automobile is rotated for obtaining a circular vector, to simplify the computing processing, and to correct a detection error due to a magnetic characteristic specific to a moving body such as the automobile. SOLUTION: The azimuth detector is provided with a controlling means which receives an output signal from a magnetic sensor outputting a detection signal corresponding to the earth magnetism provided with a phase angle of approximately 90 degrees on the same plane so as to detect an azimuth and corrects a fluctuation error from the earth magnetism due to a magnetic characteristic specific to a moving body according to the center point correction from a circular vector obtained from the rotation of a magnetic sensor. The azimuth detector is also provided with a judging function by which the center is found from the detector coordinates of at least three points on the circular vector and computing of the center is carried out on the basis of the judgement on whether an absolute value of a coordinate data difference is higher than an optional value R or not. The center of the circular vector is found according to (X1+X2)/2 and (Y1+Y2)/2, and a fluctuation error is corrected by subtracting the data of the center from the respective data of detected coordinates (X, Y) on the circular vector.

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.

Further, since the center of the detected coordinate data is obtained in any of the detection methods, for example, a signal generated by the influence of disturbance magnetism other than the normal earth magnetism or the influence of electric noise is regarded as a normal detection signal. Since the input is done and the center point is calculated based on that data, the center point becomes extremely large when the detection points due to such noise are close, and it cannot be used for direction detection. Will end up.

An object of the present invention is to detect erroneous detection data due to noise or the like and not to use it as data for center calculation for accurate azimuth detection, and to obtain the circular vector center by a simple arithmetic processing. It is an object of the present invention to provide an azimuth detecting device that can be obtained and, as a result, can reduce the calculation load and simplify the configuration.

[0008]

The present invention receives a detection signal from a magnetic sensor corresponding to geomagnetism having a phase angle of approximately 90 degrees on the same plane, and detects the azimuth based on this signal, The magnetic sensor is equipped with a control unit that corrects a variation error from the geomagnetism due to the magnetization characteristic of the moving body on which the magnetic sensor is mounted, by correcting the center point from a circular vector obtained by the rotation of the magnetic sensor. Is X based on the coordinate data corresponding to the detected coordinates of at least three points having one coordinate in common on the circular vector.
The coordinate data center calculation processing is performed only when the center of the other coordinate data of the coordinates and the Y coordinate is obtained and the absolute value of the difference between the other coordinate data exceeds an arbitrary fixed value R (arbitrary radius of the circular vector). Is performed, and the variation error is corrected 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 the earth magnetism having a phase angle of approximately 90 degrees on the same plane from the magnetic sensor, and based on this signal, the azimuth is determined. Control means for detecting and correcting a variation error from the earth magnetism due to the magnetization characteristic peculiar to the moving body on which the magnetic sensor is mounted by correcting the center point from a circular vector obtained by the rotation of the magnetic sensor. , The control means has an arbitrary starting point (X1, Y1) on the circular vector and the other two points on the circular vector having one of these starting point coordinates in common (X1, Y2).
Based on the data of (X2, Y1), the center of the circular vector is obtained by (X1 + X2) / 2 and (Y1 + Y2) / 2, and from each data of the detected coordinates (X, Y) on the circular vector. The variation error is corrected by subtracting the center data, and | X1-X2 |> = R, | Y
It is characterized in that it is determined whether or not at least one of 1-Y2 |> = R (R is a fixed value of the radius of the circular vector) is satisfied, and if so, the center correction of the circular vector is performed.

[0010]

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

For a circular vector corresponding to the geomagnetism obtained by rotating the 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), and by providing the control means for performing error correction by subtracting this central data from each coordinate data of the detected coordinates (X, Y), calculation based on a small amount of detected point data becomes possible, and the start point can be further calculated. It is possible to provide an inexpensive device by reducing the calculation load of 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 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 performs a process of correcting the output signal of the A / D converter 8 including an error due to the magnetizing characteristic peculiar to the vehicle to obtain a faithful azimuth by the geomagnetism. 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 during 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, but this calculation start point is set by adopting the turning start initial value when turning the vehicle. 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

Regarding 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 way, 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 shown 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 is not necessary, and the calculation step becomes simpler. Therefore, the starting point of at least one of the coordinates is set in advance to this coordinate 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.

In the present invention, an arbitrary starting point (X
1, Y1) and then the other two points (X1, Y2), (X
2, Y1), in order to prevent a large error when these two points pick up and detect disturbance magnetism and electric noise other than geomagnetism near the starting point, prior to the circular vector center calculation and the correction calculation. Then, it is configured to execute a determination process as to whether or not the detected data can be adopted in correctly obtaining the center of the circular vector.

That is, immediately after the starting point (X1, Y1) is determined and the vehicle body starts to turn, that is, near the starting point, the other two points (X1, Y1) due to disturbance magnetism other than geomagnetism and electrical noise.
2), (X2, Y1), they are detected at points deviated from the normal broken line locus as shown in FIG.
When a point is detected and the center point is calculated as it is, (X0 ', Y0') in the figure is recognized as the center point, and an error occurs with respect to the true center point (X0, Y0) to be obtained.

The error due to such erroneous detection can be tolerated as a slight error from the normal broken line locus at a place away from the starting point, but such a noise error near the starting point immediately after the start of detection (start of turning). Is extremely large when it is used as the data for obtaining the center point with the point on the circular vector locus as shown in the figure, and is extremely unusable as data for correction.

Therefore, in the present invention, such a starting point (X
1, Y1) It is judged whether or not the data is near the start point by judging whether or not the data is near the start point, and the judgment is made so that the center of the circular vector is not obtained and the azimuth detection by the wrong center data is not performed. It has a function.

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 the other two points due to noise or the like, first, | X1-X2 |> = R, | Y1-Y2 ｜
> = R is determined, and when either one of these is satisfied, the normal detection input is (X1 + X2) / 2, (Y1 +
Y2) / 2 is calculated to obtain the center of the circular vector, and the fluctuation error is corrected by subtracting the center data from each data of the detected coordinates (X, Y). The radius R at this time may be arbitrarily set by approximating the radius of the circle corresponding to the circular vector obtained from the turning trajectory of the vehicle.

With such a determination function, as shown in FIG. 4, when a detection input due to noise or the like occurs near the start point and this is input as (X1, Y2), (X2, Y1), It is determined that both | X1-X2 | and | Y1-Y2 | are smaller than the set radius R, and the subsequent vector center calculation calculation is not performed, so that a large detection error does not occur and the accuracy in azimuth detection is high. It is possible to obtain only such calculation results.

In the above embodiment, the center detection by three-point coordinates 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 and correct detection data is obtained. The detection / determination function for determining 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, and the center of coordinates of two points on the circular vector is obtained. It goes without saying that any configuration can be applied as long as it adopts the method.

[0028]

As described above, according to the azimuth detecting apparatus of the present invention, even if abnormal data due to noise or the like is input to the detection data on the circular vector when the vehicle turns, it can be easily detected. It is possible to obtain a correct azimuth by avoiding the determination as to erroneous detection data, and further compare the start point coordinates with one axis coordinate of the coordinates of the other two points to obtain a center coordinate as a correction value. Since it suffices to carry out the calculation with only simple calculation steps, even when the control means is configured from a microcomputer, the number of times of the calculation processing is small,
The peripheral frequency can be simplified and the price can be reduced by lowering the clock frequency and reducing the current consumption by using a low bit processor.

[0029]

[Brief description of the 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.

FIG. 4 is a detection output explanatory diagram for explaining erroneous detection due to noise or the like 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. The magnetic sensor is approximately 90 on the same plane.
The detection signal corresponding to the geomagnetism having a phase angle of 10 degrees is received, the azimuth is detected based on this signal, and the variation error from the geomagnetism due to the magnetization characteristic peculiar to the moving body on which the magnetic sensor is mounted is detected by the magnetic sensor. Is provided with a center point correction from a circular vector obtained by the rotation of the circular vector, and the control means corresponds to at least three detected coordinates having one common coordinate 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, and the absolute value of the difference between the other coordinate data exceeds an arbitrary fixed value R (arbitrary radius of the circular vector). Only the coordinate data center calculation process is executed, and the variation error is corrected by subtracting the center data from each data of the detected coordinates (X, Y) on the circular vector. Azimuth detecting device according to claim. 2. The magnetic sensor is approximately 90 on the same plane.
The detection signal corresponding to the geomagnetism having a phase angle of 10 degrees is received, the azimuth is detected based on this signal, and the variation error from the geomagnetism due to the magnetization characteristic peculiar to the moving body on which the magnetic sensor is mounted is detected by the magnetic sensor. Is provided with a center point correction from a circular vector obtained by the rotation of the circular vector, and the control means has an arbitrary starting point (X1, Y1) and one of the starting point coordinates on the circular vector. The other two points (X1, Y
2) and (X2, Y1) based on the data of (X1 + X2) / 2 and (Y1 + Y2) /
2 and the detected coordinates (X,
The variation error is corrected by subtracting the central data from each data of (Y) and the start point (X1, Y
1) and the other two points (X1, Y2), (X2, Y1), the circular vector center correction is performed.
It is determined whether at least one of X1-X2 |> = R or | Y1-Y2 |> = R (R is a fixed value of the radius of the circular vector) is satisfied, and if so, the circular vector is determined. An azimuth detecting apparatus characterized by performing a correction operation with a center point of.