JPH03293516A - Correcting method for output of azimuth detecting apparatus - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy of azimuth by a method wherein the central coordinates, ellipticity, axial direction of an ellipse output by the terrestrial magnetism which is necessary to calculate the azimuth with use of a terrestrial magnetism sensor are obtained from coordinates of a plurality of representative points on the ellipse obtained from the data during a one turn. CONSTITUTION:A host detector is constituted of a terrestrial magnetism sensor 1 which decomposes the intensity of the terrestrial magnetism into components in two directions orthogonal to each other, a turning angle sensor 2, A/D converters 31, 32, a microcomputer 4, an output means 5 and a memory. The geomagnetic azimuth data collected during one turn is averaged in an averaging process based on outputs from the sensor 2 for every turn of predetermined angles, so that a representative point is calculated. Moreover, the central coordinates of the ellipse are obtained from the representative points. It is detected whether the ellipse is linearly symmetric to a linear component connecting the central coordinates with each representative point on the circumference of the ellipse. The direction of the linear component assuming the linear symmetric relation is calculated as an axial direction of the ellipse, whereby the axial direction can be obtained correctly. Accordingly, outputs can be corrected correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention 1 relates to a method for correcting the output of a direction detecting device used in a position detecting device for detecting the current position of a moving body such as an automobile.

2. Description of the Related Art A conventional method for correcting the output of an azimuth detecting device is disclosed in, for example, Japanese Patent Laid-Open No. 190711/1983.

As shown in this example! F. A geomagnetic sensor that detects the strength of the earth's magnetic field by dividing it into components in two mutually orthogonal directions has been used as the orientation sensor of conventional orientation detection devices.
If this sensor is installed on a moving body mainly made of iron, there may be a difference in detection sensitivity in two directions.To correct this sensitivity, the maximum and minimum values of the two outputs when the moving body turns are calculated. However, in the above configuration, the geomagnetic direction is affected by the influence of the steel plates that make up the moving body. It does not take into account the case where the output circle of the sensor becomes an ellipse with a tilted axis.The present invention solves the above problems and creates an output ellipse. Aiming to calculate the direction of the axis of the earth and calculate the heading direction with high accuracy using a geomagnetic direction sensor Means for solving the four problems of the present invention In an azimuth detection device that detects the traveling direction of a moving body, which is equipped with a geomagnetic sensor that is disassembled and detected, and a turning angle sensor, averaging is performed to calculate a representative point by averaging the outputs of the geomagnetic sensor during rotation by a predetermined angle. The line symmetry of the output ellipse is determined by determining the line symmetry of the output ellipse with respect to the straight line connecting each representative point and the center coordinates, and determining the line symmetry of the output ellipse with respect to the straight line connecting each representative point and the center coordinates. The present invention is also effective in an output correction method for an orientation detection device characterized by calculating an axial direction in which the direction of a straight line that is line-symmetrical to the output ellipse is determined as the axial direction of the output ellipse. The geomagnetic azimuth data collected during one revolution is averaged every time it rotates by a predetermined angle based on the output from the turning angle sensor, and a representative point is calculated.The center coordinates of the ellipse are also determined from this representative point.Center coordinates and ellipse The axial direction can be accurately determined by determining whether the ellipse is symmetrical to the line segment connecting each representative point on the circumference and calculating the direction of the symmetrical line segment as the axial direction of the ellipse. (8) Accurate correction of the output is possible and the accuracy of the detected direction is improved This is a diagram showing the configuration of the direction detection device. In Figure 1, 1 is a geomagnetic sensor, which detects the strength of the geomagnetism by decomposing it into components in two mutually orthogonal directions. 2 is a turning angle sensor, for example Both wheel sensors, angular velocity sensors, etc. are used.4 31.32 is A
/D converter 4 is a microcomputer, 5 is an output means such as a CRT, and 6 is a memory.The operation of the output correction method of the orientation detecting device of this embodiment configured as described above will be explained below. do. In this example, the two mutually orthogonal outputs of the geomagnetic sensor are assumed to be x and y, respectively, and it is assumed that the outputs are expressed as points on the xy plane. In the flowchart, steps 201 and 202 correspond to the azimuth change amount calculation process. First, in step 201, the two mutually orthogonal outputs of the geomagnetic sensor when the vehicle turns are detected at regular time intervals so that they can be handled by a microcomputer. In the next step 202, the turning angle of the moving body is calculated from the output of the turning angle sensor.In step 203, it is determined whether the moving body has rotated by a predetermined angle. When the angle has not been rotated, the processes of steps 201 and 202 are repeated.When the angle has been rotated, the process moves to step 204.Step 204
In step 205, the data stored in step 201 is averaged to calculate a representative point.Next, in step 205, it is determined from the turning angle calculated in step 202 whether or not the moving object has completed one revolution. Repeat the process up to step 204 while the moving body rotates once to find n representative points DI to D on the circumference of the geomagnetic output ellipse. n is an integer and is the value obtained by dividing 360゛ by the predetermined angle mentioned above. Aa - When the cycle is complete, proceed to step 206.
In this case, steps 203 and 204 correspond to an averaging process. Next, step 206 corresponds to a center coordinate calculation process. center coordinates 0 (Cx, C
y). Next, in step 207, a constant p for determining the symmetry of the ellipse is determined.
In addition, initialize by assigning 1 to C, which is a counter for the number of repetitions. In step 208, the vector OD, and the vector Do-
Calculate the inner product E with eDo+- as follows: E= (X@
-Cx)* (Xs, *--Xs-s)+ (Y*-
Cy) * (Y・◆−−Y・−) ...(1)
However, by assuming the coordinates of D as (X,, Y,) and taking the inner product in this way, we can create a line segment connecting a certain representative value and the center coordinates, and p pieces of that representative value, as shown in Figure 3. The angle at which the line segment connecting the previous and p representative values intersects is calculated, and the closer the angle is to 90" (the closer the inner product is to 0), the greater the symmetry of the ellipse is determined. And here is the calculation result: The values of E and C are memorized. In step 209, C is carried forward. In step 210, it is determined whether C is greater than n.
If C is smaller than or equal to n, repeat the process in step 2.8. Conversely, if C is greater than n, the ellipse symmetry judgment process is performed for all representative points and the process moves to step 211. In step 211, step 208
Find the value of C that minimizes E from E and C memorized in step 212.Finally, in step 212, calculate the direction of vector ○D from C found in step 211, and use it as the axis direction of the exit ellipse. Once determined, the distortion rate of the ellipse is calculated from the difference between the distance from the center coordinate of the representative value in this axial direction and the distance between the representative value in the direction 90° from this axis direction and the center coordinate. A method to determine whether the direction is the major axis or the minor axis.
The steps from step 207 to step 212 correspond to the axial direction calculation step.

Thereafter, the azimuth is calculated from the output of the geomagnetic sensor using the axial strain rate of the ellipse obtained as above, and the azimuth detection result is outputted by the output means. A system that calculates a representative point by averaging the geomagnetic direction data collected during each rotation at a predetermined angle based on the output from the turning angle sensor.
Find the center coordinates of the ellipse from this representative point, determine whether the ellipse has line symmetry with respect to the line segment connecting the center coordinates and each representative point on the circumference of the ellipse, and set the direction of the line segment that is line symmetrical to the ellipse. By calculating the axial direction of the output ellipse, the axial direction of the output ellipse can be accurately calculated even when noise is superimposed on the collected data due to the influence of surrounding abnormal magnetic fields during data collection.The accuracy of the detection direction is improved. do.

Note: In this example, the line symmetry of an ellipse may be determined using the angle at which two straight lines intersect, and multiple values of b<p may be set to determine the line symmetry from three or more straight lines. Now, we can determine the line symmetry of the ellipse by calculating the inner product of the vectors.The angle at which the two straight lines intersect can be expressed as a trigonometric function to find the line symmetry. , Calculate the center coordinates of the ellipse by taking the average of the y coordinates. Find the maximum and minimum values of the x and y coordinates of the Hojo representative point. You can use the coordinates of the midpoint as the center coordinates of the ellipse ~ Effects of the invention As described above, according to the present invention, the center feature of the geomagnetic output ellipse is required when calculating the direction using the geomagnetic sensor.
Oblate wind It is possible to accurately calculate by determining from the coordinates of multiple representative points on the output ellipse obtained from the data when turning once in the axial direction, and the direction detection accuracy is improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a direction detecting device according to an embodiment of the present invention. Fig. 2 is a flowchart of an output correction method in the embodiment, and Fig. 3 is a line symmetry of an ellipse. FIG. 2 is an explanatory diagram of a determination method. ■... Geomagnetic direction sensor, 2... Turning angle sensor, 3
1, 32...A/D converter 4...Microcomputer 5...How to get it 6...Memo 19

Claims (1)

[Claims] In an azimuth detection device that detects the heading of a moving object, it is equipped with a geomagnetic sensor that separates and detects the strength of the earth's magnetic field into components in two directions orthogonal to each other, and a turning angle sensor. Compare the azimuth change amount calculation process and the azimuth change amount calculated in the azimuth change amount calculation process with a predetermined setting value, and average the geomagnetic sensor output during rotation by a predetermined angle to obtain a representative point. The averaging process calculates the center coordinates of the geomagnetic output ellipse, the center coordinate calculation process calculates the center coordinates of the geomagnetic output ellipse, and the averaging process calculates a plurality of representative points on the output ellipse from the geomagnetic sensor output when the moving body turns, and each representative point is An axial direction calculation process that determines the line symmetry of the output ellipse with respect to a straight line connecting a point and the center coordinate, and determines the direction of the straight line in which the output ellipse is line symmetrical with respect to the line as the axial direction of the output ellipse. An output correction method for an orientation detection device, characterized in that: