JPH0629730B2 - Vehicle compass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention detects the direction from the output circle center coordinate of the sensor to the coordinate indicated by the output value obtained by the geomagnetic direction sensor as the traveling direction of the vehicle. The present invention relates to a vehicle compass.

《Prior art and its problems》 Regarding the device that detects the traveling direction of the vehicle using the geomagnetic direction sensor, Automotive Technology Vol.39, No.5,
The one shown in 1985. is known, and in the geomagnetic direction sensor used in the device, a pair of windings are orthogonal to each other in a horizontal attitude.

Then, each of these windings obtains a geomagnetic component detection voltage (output value) corresponding to the interlinkage geomagnetism. When the vehicle travels in a uniform geomagnetism, the coordinates indicated by the detection voltage of those windings are used. A circle (an output circle of the geomagnetic direction sensor) is drawn on the coordinate plane.

Furthermore, during normal running of the vehicle, the direction from the coordinates of the output circle center to the coordinates indicated by the detected voltage of both windings is found as the running direction of the vehicle, and the center coordinates of the output circle are the geomagnetic field in the absence of magnetic field. It is given by the voltage obtained by both coils of the orientation sensor.

Here, when the vehicle body is magnetized, the output circle moves, which causes an error in the detection of the traveling direction.

In that case, the vehicle travels around, the detection voltage obtained by both coils of the geomagnetic direction sensor is sampled during that time, and the traveling direction detection error is corrected using the sampled detection voltage.

However, when a large vehicle such as a truck passes near the vehicle while the vehicle is traveling around, the detected voltage from the geomagnetic direction sensor is greatly disturbed in a short time, and the coordinates indicated by the detected voltage deviate greatly from the output circle. I will end up.

Therefore, the detected voltage, which is the data for correcting the traveling direction detection error, is not reliable as data, and therefore the proper direction correction is not performed, and as a result, the accurate detection of the vehicle traveling direction becomes impossible. There was a problem.

<Purpose of the Invention> The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to make a vehicle run around when a vehicle makes a round trip in order to correct a detected azimuth error caused by magnetization of a vehicle body or the like. Even if the bearing sensor output becomes abnormal due to passing near a large vehicle or a railway bridge, the vehicle's geomagnetic bearing sensor's output circle center coordinates can be accurately set to correct the bearing detection error accurately. The purpose is to provide a compass.

<< Structure of the Invention >> In order to achieve the above object, the vehicle azimuth meter according to the present invention is configured as shown in FIG.

In the figure, the geomagnetic direction sensor A decomposes the geomagnetic direction into two orthogonal directions on the horizontal plane, and the geomagnetic component in each direction is output as an electric signal indicating coordinates. The abnormal output value invalidating means B drives the vehicle. The output value is invalidated when the coordinate indicated by the output value output from the geomagnetic direction sensor A is separated from the coordinate indicated by the output value already output by a predetermined amount or more.

Then, the extracting means C extracts, from the effective output values obtained while the vehicle is traveling, a plurality of output values in which the positional relationship of the coordinates indicated by each output value is a predetermined distance interval from each other.

Further, the central coordinate calculating means D performs an averaging process on the plurality of output values extracted by the extracting means C, and the central coordinates of the output circle drawn by the coordinates indicated by the effective output values output from the geomagnetic direction sensor A. Is required.

<< Description of Embodiments >> Preferred embodiments of an apparatus according to the present invention will be described below with reference to the drawings.

FIG. 2 shows the configuration of a system to which the present invention is applied. In this system, the traveling position and traveling locus of the vehicle are displayed on a map.

Those displays are displayed on the display unit 2 of FIG.
The CPU 22 determines the running position of the vehicle.

The CPU 22 obtains the traveling position of the vehicle relative to the reference position by an integration process using the detection signals of the vehicle speed sensor 24 and the geomagnetic direction sensor 26, and the reference position is a key input unit 28 including a keyboard or the like. To the CPU 22.

The map data displayed on the display unit 20 is fetched from the external storage device 30 via the data input unit 32.
The external storage device 30 is composed of a compact disk device, a ROM, and the like.

The processing of the CPU 22 is performed using the RAM according to the contents stored in the ROM of the memory unit 34, and the map data including the traveling position of the vehicle is read from the external storage device 30 into the CPU 22. The map is displayed on the display unit 20.

A vehicle speed sensor 24 of this embodiment is shown in FIG. 3, and a vehicle speed pulse is obtained by driving a reed switch 24c on and off by a magnet 24b provided on a speedometer cable 24a.

Further, FIG. 4 shows a geomagnetic direction sensor 26, and an annular permalloy core 36 is provided with windings 38X and 38Y orthogonal to each other.

A winding 40 is wound around the permalloy core 36, and the winding 40 is formed by the permalloy core 36 as shown in FIG.
Is excited by the excitation power source 42 until just before saturation.

When the above geomagnetic direction sensor 26 is placed in a non-magnetic field,
The magnetic fluxes Φ ₁ and Φ ₂ passing through the portions S ₁ and S ₂ of the permalloy core 36 have the same magnitude but opposite directions as shown in FIG.

Therefore, when the magnetic flux linked to the winding 38X becomes zero, the detected voltage (N is the number of turns) is also zero, and similarly, the detection voltage Vy of the winding 38Y is also zero.

Further, when the geomagnetic He is applied to the geomagnetic direction sensor 26 at right angles to the winding 38X as shown in FIG. 4, the magnetic flux is biased in the permalloy core 36 by the magnetic flux density Be = μHe (μ is the magnetic permeability of the permalloy core 36). And the magnetic fluxes Φ ₁ and Φ ₂ are asymmetrical as shown in FIG.

Therefore, the detection voltage Vx having the waveform shown in FIG. 8 is obtained at the winding 38X.

Since the geomagnetism He is parallel to the winding 38Y,
The geomagnetism He does not intersect with the winding 38Y, so that the voltage Vy is not generated in the winding 38Y.

The geomagnetic direction sensor 26 is mounted on the vehicle in a horizontal posture as shown in FIG. 9, and for example, as shown in FIG.
Intersect the windings 38X and 38Y, and as a result, the windings 38X and 38Y have a detection voltage V corresponding to the geomagnetism He.
x and Vy (output values) are obtained respectively.

The detection voltages Vx and Vy are expressed by the following equations (1) and (2), respectively, where the value K is the winding constant and the value B is the horizontal component of the geomagnetism He.

Vx = KB cos θ ... Equation (1) Vy = KBsin θ ... Equation (2) Therefore, when the width direction of the vehicle is used as a reference as shown in FIG. 9, the angle θ indicating the traveling direction is θ = tan ⁻¹ (Vx / Vy) ... Formula (3):

Then, as understood from the expressions (1) and (2), when the vehicle travels in the uniform geomagnetic He, the coordinates indicated by the detection voltages Vx and Vy of the windings 38X and 38Y are changed. As shown in FIG. 10, a circle (an output circle of the geomagnetic direction sensor 26) is drawn on the XY plane coordinates, and the output circle is represented by the following equation.

Vx ² + Vy ² = (KB) ² Equation (4) Since the coordinates determined by the detection voltages Vx and Vy of the windings 38X and 38Y exist on the output circle in this manner, the CPU 22 has the coordinate points (output points). The direction from the center O of the output circle is detected as the traveling direction of the vehicle.

Here, the vehicle body of the vehicle is magnetized, and as shown in FIG.
When interlinking with 8X and 38Y, the output circle moves from the broken line position to the solid line position as shown in FIG.

As a result, an error occurs in the detection of the traveling direction of the vehicle performed by the CPU 22, and the traveling position display on the display unit 20 does not match the map display.

In that case, the correction switch 44 shown in FIG. 2 is operated, and a correction command is given to the correction controller 46.

The correction control unit 46 is mainly composed of a microcomputer, and performs a correction process for vehicle magnetization according to a correction command given from the correction switch 44.

The correction control unit 46 monitors the radius of the output circle by using the detection voltages Vx and Vy of the geomagnetic direction sensor 26, and when the radius becomes abnormal due to vehicle body magnetization as shown in FIG. Also, the above correction process is automatically performed.

FIG. 13 is a flowchart showing the procedure of the process performed by the CPU 22, and FIGS. 14 to 17 are flowcharts showing the procedure of the correction process performed by the correction control unit 46.

In FIG. 13, in the first step 100, the vehicle departure point (x ₀ , y ₀ ) is set using the key input unit 28.

In the next step 110, the vehicle traveling position (x, y) with the departure point (x ₀ , y ₀ ) as the reference position is the following formula (5),
It is obtained by the integration process according to the equation (6).

However, in both of the above equations, the value T is the elapsed time from the time of departure, the value V (t) is the vehicle speed at time t obtained based on the detection signal of the vehicle speed sensor 24, and the value θ (t) is the geomagnetic direction sensor 26. The respective vehicle traveling directions (see FIG. 9) at time t obtained based on the detected voltage are shown.

When the traveling position (x, y) of the vehicle is obtained in step 110, it is determined in step 120 whether the traveling position (x, y) of the vehicle is included in the map displayed on the display unit 20. If it is determined in step 120 that the vehicle traveling position (x, y) is not included in the currently displayed map, map data including the vehicle traveling position (x, y) is output in step 130 to the outside. It is read from the storage device 30.

Then, in step 140, the traveling position (x, y) of the vehicle is displayed on the map, and when it is determined in step 120 that the traveling position (x, y) of the vehicle is included in the displayed map. Is also displayed.

Further, in step 150, it is determined whether or not the correction mode signal from the correction control unit 46 is received. If not received, the process returns to step 110 and the traveling position (x, y) of the vehicle is simply displayed on the map. To be done.

When the correction mode signal is received, step 160
The correction mode is displayed with.

A display example of this correction mode is shown in FIG. 18, and as can be understood from the same figure, the content for instructing the driver to drive the vehicle in a circuit is displayed on the display unit 20.

Then, in step 170, it is determined whether or not the output circle center coordinates have been calculated by the correction control unit 46, and if the center coordinates have not been calculated, the process returns to step 110 and the map and the vehicle traveling position (x, y) are calculated. Along with the display, the correction mode display of step 160 is performed.

Further, when the output circle center coordinates are calculated by the correction control unit 46,
The center coordinates are fetched in step 180, and the correction mode display is ended in step 190.

During the subsequent traveling of the vehicle, the vehicle traveling azimuth θ (t) is obtained in step 110 with reference to the output circle center coordinates obtained by the correction control unit 46, and the fifth (5) using the θ (t) is obtained. , The vehicle traveling position (x, y) is obtained by the equation (6).

Next, the operation of the correction controller 46 will be described with reference to FIGS. 14 to 17.

In FIG. 14, in step 200, it is judged whether or not the output value (radius of the output circle) of the geomagnetic direction sensor 26 is equal to or larger than the specified value. The output value of the geomagnetic direction sensor 26 may be equal to or higher than the specified value when the vehicle passes through a place where the magnetic field is strong such as a railroad crossing or when the vehicle body is magnetized.

Further, in step 210, it is judged whether or not the correction switch 44 is pushed, and the correction switch 44 is pushed when it is confirmed from the display of the display section 20 that the vehicle body is magnetized.

If YES at step 200 or YES at step 210, the correction mode signal is sent to the CPU 2 at step 220.
It is sent to 2.

Further, in step 230, the output circle center coordinates are obtained by the processing described later, and when this processing ends, step '
At 230, the transmission of the correction mode signal is stopped and the correction mode display ends as described above.

FIG. 15 shows the contents of the processing in step 230, and this processing is carried out while the vehicle is traveling around.

When the vehicle travels in accordance with the correction mode display in step 160 of FIG. 13 as shown in FIG. 19, the detected voltages Vx and Vy output from the geomagnetic direction sensor 26 loop as shown in FIG. 20, for example. Locus P
Draw ₁ or P ₂ . Of these loci, the locus P ₂ is greatly different from the locus P ₁ that should be originally drawn,
This is because the detected voltage V of the geomagnetic direction sensor 26 is because the vehicle has passed around another large vehicle such as a truck when traveling around the vehicle.
This is because x and Vy became abnormal.

In FIG. 15, in the first step 300, the extraction interval constant DLT8MIN shown in FIG. 21, the constant DLTENDMAX used in the process for confirming the end of the vehicle traveling (one-round check process), and the abnormality obtained from the geomagnetic direction sensor 26. The constants DLTMAX and DLTMIN used in the data collection determination process for invalidating the various detection voltages Vx and Vy are set.

The extraction interval constant DLT8MIN is a constant preset based on the radius of the output circle, and the constant DLTEN
DMAX is a constant that sets a neighborhood area of an extraction representative point (described later) extracted in the initial stage (for example, the first stage).

Further, the constant DLTMAX and the constant DLTMIN are used as a criterion for judging whether the output value of the geomagnetic direction sensor 26 is valid or invalid.

Then, in step 310, the detected voltages Vx and Vy obtained at that time are the first extracted representative points {X (1), Y.
(1)} is extracted and stored, and the extracted representative point number c is set to the value 1.

In the next step 320, the output voltages Vx and Vy obtained from the geomagnetic direction sensor 26 are collected. Are these detected voltages Vx and Vy appropriate as data for obtaining the output circle center coordinates in the next step 330? It is determined whether or not.

Here, in step 330, as is understood from FIG. 21, every time the detected voltage Vx, Vy is obtained from the geomagnetic direction sensor 26, the output point Q on the coordinate indicated by the obtained detected voltage Vx, Vy. (Q 1 _{to Q 6)} is determined whether distant from the previous output point (e.g., if the output point Q ₃ are the output point Q ₂₎ more than a predetermined amount, in which case a distance of more than a predetermined amount The detection voltages Vx and Vy indicating the output point Q are invalidated as abnormal data. The processing procedure is performed according to the flowchart of FIG.

In step 500 in FIG. 16, the distance DLT between the coordinates (PREX, PREY) indicated by the immediately preceding detection voltages Vx, Vy and the coordinates (x, y) indicated by the next detection voltages Vx, Vy is obtained by the following equation. To be

Then, in step 510, the coordinates (x, y) are temporarily stored as output data.

Next, at step 520, the distance DLT and the previously set constant DLTMIN are compared in size to determine the distance DLT as a constant D.
If it is larger than LTMIN, the routine proceeds to step 530, where the distance DLT is compared with the previously set constant DLTMAX. And the distance DL
When T is smaller than the constant DLTMAX, the detection voltages Vx and Vy that give the coordinates (x, y) are appropriate data.

If the distance DLT is smaller than the constant DLTMIN in step 520, the vehicle is stopped and the detection voltage V
Since x and Vy hardly change, the above coordinates (x,
The detection voltages Vx and Vy that give y) are invalidated as unnecessary and take in the next detection voltages Vx and Vy.

If the distance DLT is larger than the constant DLTMAX at step 530, the output point Q is largely deviated from the original position, such as the output point Q _{3 in} FIG. 21, and therefore the coordinates (x, y) are given. The detection voltages Vx and Vy are invalidated.

As described above, in step 330 of FIG. 15, only the effective detection voltages Vx and Vy are taken in as data for calculating the output circle center coordinates, and the process proceeds to the next step 340.

Then, in step 340, the coordinates (x, y) indicated by the effective detection voltages Vx, Vy and the first extraction point {X are displayed.
The distance DLT8 between (1) and Y (1)} is obtained by the following equation.

Further, in step 350, it is determined whether or not the extracted representative score C has reached the value 10. Since the number C is 1 at the start of the round traveling, the process proceeds to step 370.

Then, when the extracted representative score C reaches the value 10, the routine proceeds to step 360, where the one-round check processing is performed.

Therefore, the one-round check process of this step 360
A description will be given according to the flowchart in the figure.

The round check processing, after extracting representative points c reaches the value 10, is repeated every time the output point R ₁ to R ₆ are obtained, when R ₆ is obtained as understood from FIG. 21 Then, the process ends.

In FIG. 17, the extraction representative point (c =
The counter value n indicating the number 1) is set to 1. Then, in the next step 610, it is determined whether or not the counter value n has reached the value 2, and since the counter value n is the value 1, the process proceeds to step 620.

Then, in step 620, the distance DLTEND between the extracted representative point (c = 1) and the output point R ₁ is calculated by the following equation.

Then, in the next step 630, the magnitude of the distance DLTEND and the previously set constant DLTENDMAX are compared, and as can be understood from FIG. 21, the distance DLTEND is larger than the constant DLTENDMAX at the output point R ₁ . In step 640, the counter value n is n
It counts up to +1 and returns to step 610.

It should be noted that whether or not the traveling of the vehicle is completed is confirmed by whether or not the output point R exists near the extracted representative point (c = 1 to 4) extracted in the initial stage. In the present embodiment, if the output point R exists within the circle having the radius DLTENDMAX centered on the extracted representative point (c = 1), it is confirmed that the vehicle orbital traveling has ended.

Therefore, when the counter value n reaches 2 in step 610, the one-round check process is once terminated and the next output point R ₂ is obtained. Then, for this output point R ₂ , steps 600 to
The process of step 630 is performed, and thereafter, the same process is similarly performed on the output points R ₃ , R ₄ , and R ₅ .

Then, the output point R ₆ is obtained, and the distance DLTEND and the constant D are obtained.
When the magnitude of LENDMAX is compared in step 630, the distance DLTEND is smaller, as can be understood from FIG. 21, so that it is confirmed that the vehicle is running round, and the one-round check process is finished.

As described above, the one-round check process is performed in step 360 of FIG. 15, and if the end of the vehicle round trip is not yet confirmed, or if the extracted representative score C has not reached the value 10, go to step 370. move on.

In this step 370, the extraction interval constant DLT8MI
It is determined whether or not the distance DLT8 has reached N, and when the distance DLT8 is shorter than the extraction interval constant DLT8MIN, the process returns to step 320, and the following steps 350 to 3 are performed.
The process of 70 is repeated. Since the above process is set to be repeated in about 50 ms, the coordinates (x, y) at the initial stage of acquisition are shorter than the extraction interval constant DLT8MIN.

After that, when the distance DLT8 reaches or exceeds the extraction interval constant DLT8MIN, the process exits to step 380, and in step 380, the extraction representative score C is incremented.

Further, in step 390, the coordinate (x, y) at that time is 2
The th extraction representative point {X (2), Y (2)} is extracted and stored. Then, the above steps 320 to 3370
The process of is repeated.

As described above, a plurality of extracted representative points (C = 1, C = 2, ... C = 10) on the locus P shown in FIG. 21 are sequentially extracted while the vehicle is traveling around, and their coordinates are stored.

Then, in step 380, the extracted representative score C reaches 10,
This is confirmed in step 350, and when it is confirmed in step 360 that the vehicle orbital traveling has ended, the routine proceeds to step 400.

In this step 400, the detected voltage V which gives all the stored representative points (C = 1, C = 2, ... C = 10) are stored.
The averaging process (arithmetic mean) of x and Vy is performed according to the following equation, whereby the center coordinates C _X and C _Y of the output circle are obtained.

As described above, in this embodiment, it is determined whether or not the detection voltages Vx and Vy obtained from the geomagnetic direction sensor 26 are appropriate as data for obtaining the output circle center coordinates O, and the effective detection voltages Vx and Vy are determined. Output circle center coordinates O based on
Therefore, even if the detected voltages Vx and Vy obtained from the geomagnetic direction sensor 26 become abnormal when passing through the vicinity of another large vehicle such as a truck or an iron bridge when the vehicle travels around the output circle center. It is possible to accurately obtain the coordinate O.

Since the vehicle traveling azimuth is calculated with reference to the output circle center coordinates O, the azimuth detection error can be accurately corrected.

Further, the detection voltage Vx obtained from the geomagnetic direction sensor 26,
Even when Vy hardly changes due to the stop of the vehicle, the detected voltages Vx and Vy are invalidated, so that unnecessary data can be eliminated.

Further, in the present embodiment, the output circle center coordinate O is obtained by the arithmetic mean of the detection voltages Vx and Vy which give all the extracted representative points (C = 1, C = 10), so the coordinates indicated by the output value of the geomagnetic direction sensor 26. Even if the locus P drawn by is significantly distorted with respect to the perfect circle, the distortion error is canceled out, so that a more accurate center coordinate O can be obtained.

Further, since the completion of the round trip of the vehicle can be surely confirmed by the one-round check process, the automation of the process for correcting the azimuth detection error becomes sure.

<< Effects of the Invention >> As is clear from the above description, the vehicular azimuth meter according to the present invention is within a predetermined amount from the coordinates indicated by the already output output value among the output values obtained from the geomagnetic direction sensor. Since the output circle center coordinates are calculated based only on the valid output values in the table, when the geomagnetic component detection voltage becomes abnormal when passing around other large vehicles such as trucks or near railway bridges while traveling around the vehicle. Even in this case, the azimuth detection error can be accurately corrected.

In addition, among the valid output values, a plurality of output values are extracted such that the positional relationship of the coordinates indicated by each output value is a predetermined distance interval from each other, and the center coordinates of the output circle are calculated by averaging the plurality of extracted output values. Therefore, even if the locus drawn by the coordinates indicated by the output value obtained while the vehicle is running is distorted to the true circle due to the disturbance of the earth's magnetic field, the output circle that the output value should originally draw It is possible to accurately obtain the center of.

Therefore, it is possible to reliably eliminate the azimuth detection error due to the magnetization of the vehicle body or the like and obtain the accurate azimuth.

[Brief description of drawings]

1 is a block diagram showing a preferred embodiment of a vehicular azimuth meter according to the present invention, FIG. 3 is a configuration explanatory view of a vehicle speed sensor, and FIG. 4 is a configuration of a geomagnetic direction sensor. Explanatory diagram, FIG. 5 is an explanatory diagram of the excitation characteristic of the geomagnetic direction sensor,
FIG. 6 is a characteristic diagram showing a magnetic flux change in the permalloy core of the geomagnetic direction sensor in the absence of a magnetic field, FIG. 7 is an explanatory view of the detection action of the geomagnetic direction sensor, FIG. 8 is a detection voltage characteristic diagram of the geomagnetic direction sensor, and FIG. FIG. 9 is an explanatory view of the vehicle traveling direction, the first
FIG. 0 is an explanatory diagram of an output circle, FIG. 11 is an explanatory diagram showing a state in which a magnetic field other than geomagnetism is applied to the geomagnetic direction sensor, FIG. 12 is an explanatory diagram showing movement of the output circle due to magnetization of the vehicle body, and FIG. Flowchart showing the processing procedure of the CPU 22, 14th
FIG. 15, FIG. 16, FIG. 16 and FIG.
6 is a flow chart showing the processing procedure of No. 6, FIG. 18 is an explanatory view of a display example for instructing traveling around, FIG. 19 is an explanatory diagram showing the traveling situation of the vehicle, and FIG. FIG. 21 is an explanatory view showing a comparison with an output circle, and FIG. 21 is an explanatory view of a correction action of the correction control unit 46. 20 ... Display unit 22 ... CPU 24 ... Vehicle speed sensor 26 ... Geomagnetic direction sensor 28 ... Key input unit 30 ... External storage device 32 ... Data input unit 34 ... Memory unit 36 ... Permalloy core 38X, 38Y ... Winding 40 ... Winding (for excitation) 42 ... Excitation power supply 44 ... Correction switch 46 ... Correction control unit

Claims (1)

[Claims] 1. A geomagnetic direction sensor in which the geomagnetic direction is decomposed into two directions orthogonal to each other on a horizontal plane, and geomagnetic components in each direction are output as electric signals indicating coordinates, and a geomagnetic direction sensor output while the vehicle is traveling. An abnormal output value invalidating means for invalidating the output value when the coordinate indicated by the output value is separated from the coordinate indicated by the output value by a predetermined amount or more, and an effective output value obtained while the vehicle is traveling. Among these, the extraction means for extracting a plurality of output values whose positional relationship of the coordinates indicated by each output value is a predetermined distance interval from each other, and the averaging processing of the plurality of extracted output values are performed, and output from the geomagnetic direction sensor. A vehicle azimuth meter, comprising: a central coordinate calculating unit that obtains central coordinates of an output circle drawn by coordinates indicated by effective output values.