JPH0749232A - Bearing detection device for vehicle - Google Patents

Abstract

PURPOSE:To provide a highly accurate drive guide by correcting an earth magnetism vector via the calculation of a body magnetism vector from an earth magnetism vector along at least two vehicle travel directions and the magnitude thereof. CONSTITUTION:A direction sensor 1 outputs an earth magnetism detection signal Es and a reference signal Er constituting an earth magnetism vector. A phase detector 2 finds the travel direction of a vehicle from the signals Er and Es. Furthermore, an arithmetic unit 5 finds the current position of the vehicle from a travel distance outputted from a travel sensor 3 or the like, and then computes and outputs a rectilinear distance to a destination and the direction thereof. On the other hand, a correction calculation circuit 16, upon receipt of an instruction on calculation, arithmetically operates the phase difference of a signal component due to body magnetism and the level thereof on the basis of each detected phase and signal level along at least two vehicle travel directions. Then, the circuit 16 generates such a correction signal as agreeing to the signal component due to the body magnetism. Thus, an error signal component contained in the signal Es due to the body magnetism can be eliminated by subtracting the correction signal therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive guide device, and more particularly to correcting the direction of the direction sensor when a detection error occurs in the direction sensor due to a change in vehicle magnetism during traveling. The present invention relates to a vehicle azimuth detecting device.

[0002]

2. Description of the Related Art In a conventional vehicle guidance system, when a driver sets and inputs data of a starting point and a destination point examined on a map, the phase of a geomagnetic detection signal output from a direction sensor as the vehicle travels. The traveling direction of the vehicle is detected based on, and the current position of the vehicle is calculated for each unit traveling distance from the traveling direction of this vehicle and the traveling distance detected by the distance sensor,
There is a device which obtains and displays each of the straight line distance from the current position to the destination and the direction of the destination.

By the way, the direction sensor used in the above-mentioned device outputs an AC signal obtained by constant-speed rotation of a geomagnetic detection coil or the like having an induced magnetic field in the direction of geomagnetism as a geomagnetic detection signal. If a direction sensor is installed in the vehicle, it will be affected by the vehicle magnetism that has a unique size and direction for each vehicle due to the motor, electromagnetic actuator, etc. installed in the vehicle, and the geomagnetic detection signal output by the direction sensor will be affected. Will include an error due to the vehicle body magnetism.

Therefore, in order to eliminate the error of the direction sensor due to the magnetism of the vehicle body, the error is reduced by a means such as providing an electromagnet near the direction sensor which generates a magnetic field in a direction canceling the magnetism of the vehicle body. There was a certain amount of error remaining, and there was a problem that the error of the direction sensor was accumulated and became conspicuous as the traveling distance increased and the destination was approached.

Therefore, the inventors of the present application, as a means for almost completely eliminating the error of the direction sensor due to the magnetism of the vehicle body, when the vehicle is placed in a factory, the direction sensor when the vehicle is arranged in each of the four directions of north, south, east, west and We have proposed a device that corrects the detected value in the traveling direction of the vehicle by measuring the deviation between the detected value of the vehicle and the traveling direction of the vehicle in advance using a checker, and setting this deviation as correction data. [Japanese Patent Application Sho 5
6-125320 (JP-A-58-27009)].
According to this device, the detection error of the direction sensor due to the magnetism of the vehicle body can be almost completely corrected, and a highly accurate drive guide can be realized.

[0006]

However, even if the error of the direction sensor due to the magnetism of the vehicle body is corrected as described above, an error may occur during use. The cause of the error was clarified. It was found that the car body is magnetized when passing through a case where a strong magnetic field is generated with a high voltage and a high current of the overhead wire, and the state of the car body becomes different from that at the time of correction. However, to determine whether the error of the direction sensor is due to changes in vehicle magnetism, bring the vehicle to a facility equipped with a marker indicating north, south, east, and west and measure the detection error for the absolute azimuth indicated by the marker using a dedicated checker. I don't know unless I look at it.

Therefore, the user will use the drive guide without being aware of the error caused by the change in the vehicle body magnetism. When the travel guide device is used in such a state, the travel guide becomes longer as the travel distance increases. There is a problem that the error in the direction and the distance to the destination becomes large.

[0008]

The present invention has been made in view of the above, and includes a vehicle azimuth detecting device, a direction sensor for detecting a geomagnetic vector that is a combination of geomagnetism and vehicle body magnetism,
Vector detecting means for detecting the geomagnetic vector when the direction sensor faces at least two vehicle traveling directions; and storage means for storing the magnitude of the geomagnetism in advance.
Vehicle body magnetic vector calculation means for calculating a vehicle body magnetic vector representing the magnetism of the vehicle body from the at least two vehicle geomagnetic vectors in the traveling direction and the magnitude of the earth magnetism stored in the storage means, and the geomagnetic vector of the direction sensor for the vehicle body A correction means for correcting the magnetic vector is used.

Further, a direction sensor for detecting a geomagnetic vector obtained by combining the geomagnetism and the vehicle body magnetism, a vector detecting means for detecting the geomagnetic vector when the direction sensor faces at least two vehicle traveling directions, and the geomagnetic field Storage means for pre-storing the magnitude, and for each geomagnetic vector detected by the vector detecting means, a circle having the radius of the magnitude of the geomagnetism centered on the coordinates of the end of the geomagnetic vector is obtained and the intersection of the circles is obtained. Coordinate calculation means for obtaining the coordinates, vehicle body magnetic vector calculation means for calculating the vehicle body magnetic vector from the coordinates of the starting point of the geomagnetic vector and the intersection coordinates obtained by the coordinate calculation means, and the geomagnetic vector of the direction sensor as the vehicle body magnetic vector. And a correction means for making correction based on the above.

Further, a direction sensor for detecting a geomagnetic vector which is a combination of the geomagnetism and the vehicle body magnetism, a vector detecting means for detecting the geomagnetic vector when the direction sensors face a plurality of vehicle traveling directions, and a magnitude of the geomagnetism. For each pair of geomagnetic vectors detected by the vector detecting means, a circle having the radius of the magnitude of the geomagnetism with the coordinate of the end of the geomagnetic vector as the center point Coordinate calculation means for obtaining the intersection coordinates, average coordinate calculation means for obtaining the average coordinates of the plurality of intersection coordinates obtained for each of the pair of geomagnetic vectors by the coordinate calculation means, starting coordinates of the geomagnetic vector and the average coordinate calculation. The vehicle body magnetic vector calculating means for calculating the vehicle body magnetic vector from the average coordinates obtained by the means, and the geomagnetic vector of the direction sensor for the vehicle It was assumed and a correcting means for correcting, based on the magnetic vector.

[0011]

Next, the operation of the present invention will be described. The direction sensor detects a geomagnetic vector that is a combination of geomagnetism and vehicle body magnetism. Further, the magnitude of the geomagnetism is stored in advance by the storage means. Further, the vehicle body magnetic vector calculation means calculates a vehicle body magnetic vector representing the magnetism of the vehicle body from the at least two geomagnetic vectors in the traveling direction of the vehicle and the magnitude of the geomagnetism stored in the storage means. Then, the correcting means corrects the geomagnetic vector of the direction sensor based on the vehicle body magnetic vector.

Further, the direction sensor detects a geomagnetic vector which is a combination of geomagnetism and vehicle body magnetism. Further, the magnitude of the geomagnetism is stored in advance by the storage means. Further, by the coordinate calculating means, for each geomagnetic vector detected by the vector detecting means, a circle having the radius of the magnitude of the geomagnetism with the coordinates of the coordinates of the end of the geomagnetic vector as the center point is obtained, and the intersection coordinates of the circle are obtained. The vehicle body magnetic vector calculating means calculates the vehicle body magnetic vector from the coordinates of the start point of the geomagnetic vector and the intersection coordinates obtained by the coordinate calculating means.
Then, the correcting means corrects the geomagnetic vector of the direction sensor based on the vehicle body magnetic vector.

Further, the direction sensor detects a geomagnetic vector that is a combination of geomagnetism and vehicle magnetism. The magnitude of the geomagnetism is stored in advance by the storage means. Further, by the coordinate calculating means, for each of a pair of geomagnetic vectors detected by the vector detecting means, a circle having the radius of the magnitude of the geomagnetism as the center point of the coordinates of the end of the geomagnetic vector is obtained, and the intersection coordinates of the circles are calculated. The average coordinate calculation means calculates the average coordinates of a plurality of intersection coordinates obtained for each of the pair of geomagnetic vectors by the coordinate calculation means, and the vehicle body magnetic vector calculation means calculates the start coordinates of the geomagnetic vector and the average coordinates. The vehicle body magnetic vector is calculated from the average coordinates obtained by the calculating means. Then, the correcting means corrects the geomagnetic vector of the direction sensor based on the vehicle body magnetic vector.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. First, the configuration will be described. 1 is a direction sensor, which has, for example, a geomagnetic detection coil that is rotated at a constant speed by a motor, and a geomagnetic detection signal Es from this detection coil is used as a reference signal Er having a frequency that matches the rotation speed of the motor. I am trying to output with. The geomagnetic vector signal is composed of the geomagnetic detection signal Es and the reference signal Er.

2 is a geomagnetic detection signal E from the direction sensor 1.
is a phase detector that detects the phase difference between s and the reference signal Er, and the detected phase is the traveling direction θ of the vehicle with respect to the reference azimuth.
Becomes a signal indicating. The direction θ detected by the phase detector 2 is output as digital data. For example, with respect to the west, a 360 ° azimuth is divided into 256 clockwise parts. , 0 in the west, 64 in the north, 128 in the east and 192 in the south.

Reference numeral 3 denotes a traveling sensor which outputs a number of pulses proportional to the number of rotations of the wheel. Reference numeral 4 denotes a traveling distance obtained by counting the pulses from the traveling sensor 3 and outputting a pulse for each unit traveling distance ds. The counter 5 obtains the current position of the vehicle based on the traveling direction θ of the vehicle and the traveling distance ds, and further, based on the data of the current position, the straight line distance L to the destination and the direction θ _{G of the} destination. A computing device for computing and outputting, 6 is a departure point (x _o , y _o ) checked on the map,
It is a keyboard for the driver to input each of the destination points (x _G, y _G ). Here, as the calculation by the calculation device 5, first, regarding the current position (x, y) of the vehicle,

[0017]

[Equation 1] For the linear distance L to the destination and the direction θ _G of the destination,

[0018]

[Equation 2] Is calculated.

Reference numeral 7 is a display device for displaying the linear distance L to the destination and the direction θ _G of the destination output from the arithmetic unit 5. A bar graph 8 is provided for the display of the linear distance L and the destination is displayed. As the bar graph 8 is approached, the remaining distance to the destination is displayed by deleting the bar graph 8 from the lower side, and a plurality of display arrows 9 indicating the direction of the destination are provided around the bar graph 8 to indicate the destination. One of the display arrows 9 indicating the ground is turned on.

On the other hand, an error detection circuit 10 is provided between the direction sensor 1 and the phase detector 2 for detecting that an error has occurred in the geomagnetic detection signal Es from the direction sensor 1 due to a change in vehicle magnetism. The output of the error detection circuit 10 activates the alarm device 11 including an alarm lamp, a buzzer, and the like. FIG. 2 is a block diagram showing a specific embodiment of the error detection circuit 10 in the embodiment of FIG.

In FIG. 2, an error detection circuit 10 includes a phase detector 12 for detecting a phase difference θ between the geomagnetic detection signal Es and a reference signal Er, and a magnitude of the geomagnetic detection signal Es at a predetermined phase difference (in the direction of the vehicle). geomagnetic magnitude of the vector signal) in a predetermined angular direction for, namely a storage circuit 13 previously stores a signal level S _O, terrestrial magnetism detection signal phase detector 12 is stored in the storage circuit 13 Es
When the phase difference corresponding to the signal level S ₀ is detected, it is compared with Es using the signal level S ₀ of the memory circuit 13 as a reference signal, and is output when the absolute value of the difference between the two is equal to or more than a predetermined value. And an amplifier 15 for amplifying the output of the comparator 14 to operate an alarm lamp or a buzzer provided in the alarm device 11 shown in FIG. Incidentally, the geomagnetic detection signal Es and the reference signal Er for the phase detector 2 of FIG.
Is still applied via the error detection circuit 10.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described. First, when a vehicle having a signal vector obtained by the magnitude and phase difference of the geomagnetic detection signal Es with respect to the reference signal Er output from the direction sensor 1 is placed at the same point, for example, on a turntable and rotated once, a trajectory is drawn as shown in FIG. It is expressed as. In FIG. 3, the signal vector C is the direction sensor 1.
This is a geomagnetic detection signal Es output from the signal vector C. This signal vector C is a signal vector A having a predetermined phase difference from the reference signal Er due to the vehicle body magnetism and a signal vector B due to the original geomagnetism in the traveling direction of the vehicle. Given as a composite vector. Therefore, in the embodiment of FIGS. 1 and 2,
For example, as shown in the signal vector of FIG. 3, the reference signal Er
Geomagnetic detection signal Es obtained when the vehicle is oriented in a predetermined direction in which the phase difference of the geomagnetic detection signal Es with respect to is θ _0.
Signal level, that is, the magnitude S ₀ of the signal vector C is stored in the storage circuit 13 together with the phase difference θ ₀ .

Next, while the phase difference θ ₀ and the signal level S ₀ with respect to the storage circuit 13 are stored in this manner, the vehicle passes through a strong magnetic field such as a railroad crossing while traveling. The magnetism changes, and for example, as shown in the signal vector of FIG. 4, a change in the vehicle body magnetism causes a change in the phase and magnitude that become the signal vector A ′. Therefore, the phase difference of the geomagnetic detection signal Es with respect to the reference signal Er It is assumed that the signal level at θ ₀ increases like S _n . Such a change in the signal level of the geomagnetic detection signal Es at the predetermined phase difference θ ₀ after the change of the vehicle body magnetism is caused when the vehicle is oriented in the phase detector 12 to detect the predetermined phase difference θ _0. , The signal level S ₀ at the phase difference θ ₀ stored in advance from the memory circuit 13 based on the detection output of the phase difference detector 12 is given to the comparator 14 as a reference signal. At this time, the signal level of the geomagnetic detection signal Es is S _n becomes as shown by a signal vector C 'of FIG. 4, the absolute value of Yes difference _{S n> S 0 | S n} -S 0 | occurs the comparator 14 outputs to become a predetermined value or more [Delta] S, The alarm lamp or alarm buzzer of the alarm device 11 is operated via the amplifier 15 to notify the driver that an error has occurred in the detection signal of the direction sensor 1 due to a change in the vehicle body magnetism.

When an alarm is output from the alarm device 11, the error signal component due to the vehicle body magnetism contained in the geomagnetic detection signal Es from the direction sensor 1 is changed according to another embodiment which will be described later. Correction for removal is performed.

FIG. 5 is a block diagram showing the first embodiment. In this embodiment, the phase difference θ of the geomagnetic detection signal Es with respect to the reference signal Er detected during traveling and the magnitude of the signal, that is, the signal level S. Based on the above, the signal component due to the vehicle body magnetism included in the geomagnetic field detection signal Es is calculated, the signal due to the vehicle body magnetism is generated as a correction signal, and the geomagnetic field detection signal Es is corrected by subtracting the signal from the geomagnetic field detection signal. It is characterized by

First, the structure will be described.
The phase detector 2, the traveling sensor 3, the distance counter 4, the arithmetic unit 5, the keyboard 6 and the display 7 are the same as those in the embodiment of FIG. 1, and in addition to this, the reference signal Er from the direction sensor 1 and the geomagnetism are added. The correction arithmetic circuit 16 to which the detection signal Es is input is provided in the preceding stage of the phase detector 2. The correction arithmetic circuit 16 has the circuit configuration shown in FIG.

In FIG. 6, 17 is a phase detector for detecting the phase difference θ of the geomagnetic detection signal Es with respect to the reference signal Er, and 18 is a signal level of the geomagnetic detection signal Es, for example, an effective value or a rectified DC voltage. Level detector,
Reference numeral 20 denotes a geomagnetic detection signal Es based on the detection phase difference θ of the phase detector 17 and the detection level S of the level detector 18.
Is a calculator for calculating each of the phase difference θ ₀ and the signal level S ₀ of the signal component due to the vehicle body magnetism included in the reference signal Er.

The calculation of the phase difference θ ₀ and the signal level S ₀ by the calculator 20 is performed by using the vehicle body magnetism signal vector A and the earth magnetism signal vector A as the geomagnetic detection signal Es output from the direction sensor 1 as shown in FIG. A geomagnetic signal vector B, which is represented by a composite vector C of B and B, and which is similar to that generated when the vehicle is placed on the turntable at the same point for one rotation, depending on the traveling direction of the vehicle.
Since a locus of a circle due to the rotation of is drawn, if the center (x _o , y _o ) of this circle is obtained from the phase difference θ of the signal vector C and the signal level S, the phase difference θ of the signal vector A due to the vehicle body magnetism. _o and the size S ₀ are respectively obtained,
It is possible to generate a signal component included in the geomagnetic detection signal corresponding to the vehicle magnetism as a correction signal. That is, the circle equation in FIG. 7 is

[0029]

[Equation 3] Therefore, at least two points on the circumference, for example (x
Two points of ( ₁ , y ₁ ) and (x ₂ , y ₂ ) are selected, and based on the above equation 3,

[0030]

[Equation 4] The center of rotation (x _0, y ₀ ) of the signal vector B can be obtained by solving the simultaneous equation of In addition, in the calculation of Expression 4, the signal vector B is a geomagnetic vector, which is unique to the direction sensor 1, and the magnitude R thereof is a value known in advance.

In addition, in order to remove the influence of noise and the like in the calculation of Expression 4, in practice, the above calculation is performed a plurality of times to obtain the average value of the calculated (x _0, y ₀ ). Is desirable. From the value of (x _0, y ₀ ) thus obtained,
The signal level S ₀ and the phase difference θ ₀ of the signal vector A due to the vehicle body magnetism are

[0032]

[Equation 5] Ask by. As a specific configuration of the arithmetic unit 20 for performing the arithmetic operations of the equations 4 and 5, the phase difference θ from the phase detector 17 and the detection level S from the level detector 18 are respectively set as shown in FIG. By inputting to the sine calculator 20a and the cosine calculator 20b, the coordinates x = Scos θ and y = Ssin θ on the circumference of the signal vector C of FIG.
The outputs of the sine and cosine calculators 20a and 20b are input to the calculator 20c to solve the simultaneous equations of the equation (4),
The center of rotation (x _0, y ₀ ) is obtained in the same manner as described above, and the calculation unit 2
The signal level S ₀ and the phase difference θ _o of the signal vector A shown in the equation (5) are calculated and output at each of 0d and 20e. Of course, the calculation in the calculator 20c may be a program calculation using a microcomputer.

Referring again to FIG. 6, each of the phase difference θ _o and the signal level S ₀ representing the signal component due to the vehicle body magnetism contained in the geomagnetism detection signal Es calculated by the calculator 20 has a sine wave oscillator 21. And the multiplier 22. The sine wave oscillator 21 performs a phase control based on the calculated phase difference θ _o from the calculator 20 with respect to the reference signal Er θ _o.
A sine wave signal having a phase delay of is oscillated and output to the multiplier 22, and in the multiplier 22, the sine wave signal from the sine wave oscillator 21 is set by a predetermined count setting based on the operation signal level S ₀ from the calculator 20. The signal level is converted into the signal level S ₀ calculated by the calculator 20, and the multiplier 22 converts the signal level into a signal component due to vehicle magnetism that has a phase difference θ _o with respect to the reference signal Er and has a signal level S _0. The matching correction signal Eo is output.

The correction signal Eo is given to the subtractor 24 to which the geomagnetic detection signal Es is input, and the geomagnetic detection signal Es is supplied.
By subtracting the correction signal Eo from, the signal component due to the vehicle body magnetism included in the geomagnetic field detection signal Es is removed, and the error contained in the geomagnetic field detection signal Es is corrected by the vehicle body field magnetism. The correction action in the subtractor 24 is as shown in FIG.
This is equivalent to the removal of the signal vector A due to the vehicle body magnetism in the signal vector diagram of No. 3, and as a result, the geomagnetic detection signal Es output from the subtractor 24 is only the signal vector B due to the geomagnetism. Is
The error signal component due to the vehicle body magnetism is not included at all.

Next, the correction operation of the first embodiment will be described with reference to FIGS. First, one of the following methods is used as a correction calculation start command to the correction calculation circuit 16. (B) The traveling direction of the vehicle in which the correction calculation is started is determined in advance in a plurality of directions, and the correction calculation is performed when the detected phase difference of the phase detector 17 that matches any of the plurality of calculation start directions is obtained. . (B) The error detection function of the error detection circuit 10 shown in FIGS. 1 and 2 is provided in the correction arithmetic circuit 16, and the detection level from the level detector 18 when a predetermined phase difference is generated is stored in advance. A correction calculation is performed automatically when an error that causes a difference of a predetermined value or more is detected, or by a correction command from a keyboard or the like after an alarm. (C) The correction calculation is instructed for every fixed time or every fixed mileage.

As described above, when a calculation command is issued to the correction calculation circuit 16 by any of the above (a) to (c), at least the phase detector 17 and the level detection when the vehicle faces two different directions. Based on each detected phase θ of the device 18 and the signal level S, the calculation according to the equation 4 is executed, and FIG.
The rotation center (x _o , y _o ) of the signal vector B at is calculated, and based on the center coordinates (x _o , y _o ), the equation 5
Calculates the phase difference θ _o of the signal component due to the vehicle body magnetism and the signal level S ₀ , and generates the correction signal Eo that matches the signal component due to the vehicle body magnetism by the phase control of the sine wave oscillator 21 and the level control for the multiplier 22. As shown in the signal waveform diagram of FIG.
In contrast to the geomagnetic detection signal Es having a phase difference θ and a signal level of S, the phase difference θ _o set by the calculator 20 and the correction signal Eo having a signal level S ₀ are subtracted from the geomagnetic detection signal Es. The error signal component due to the vehicle body magnetism included in the signal Es is removed, and the geomagnetic correction signal corresponding to the signal vector B of FIG. 7 having the phase difference due to the geomagnetism and the signal level is supplied to the phase detector 16 shown in FIG.
When the distance counter 4 outputs a pulse to the unit traveled distance ds, the arithmetic unit 5 outputs
The linear distance L to the predetermined destination based on 2 and the direction θ _G of the destination are calculated and displayed on the display 7.

In the embodiments of FIGS. 5 and 6, since the arithmetic unit 20 is provided in the correction arithmetic circuit 16 because the device configuration is likely to be complicated, the correction arithmetic circuit 16 has a phase controllable sine wave transmission. 6 is provided with only the multiplier 21 and the multiplier 22 in which the coefficient can be set, and after the alarm is issued by the error detection of the error detection circuit 10 shown in FIGS. Phase detector 17, level detector 18, and calculator 20 in the error calculation circuit 16
With a built-in checker connected to a connector, in this state, the vehicle is directed in at least two predetermined directions to calculate the phase difference θ _o of the signal component due to the vehicle body magnetism and the signal level S ₀ , and to the sine wave oscillator 21, The configuration of the error calculation circuit 16 may be simplified by setting the phase difference θ _o and setting the coefficient for outputting the signal level S ₀ to the multiplier 22.

FIG. 10 is a block diagram showing a second embodiment. This embodiment is characterized in that a non-rotation type direction sensor having no rotation mechanism is used as the direction sensor. First, the configuration will be described. The direction sensor 25 includes a pair of detection coils 27 and 28 that are orthogonal to the ring-shaped core 26.
Is wound, and the exciting coil 29 is wound in the circumferential direction of the core 26. The direction sensor 25 detects the direction of the geomagnetism by detecting the exciting coil 29 wound around the core 26.
On the other hand, a pulse signal or an AC signal having a predetermined frequency is supplied from the oscillator 30 to excite the exciting coil 29, and the exciting coil 29 excites the detecting coil 2 arranged orthogonally.
A signal voltage obtained by differentiating the pulse signal or the alternating current signal is induced in 7, 28.

When no external magnetic field is applied to the direction sensor 25, the detection signals of the detection coils 27 and 28 show odd harmonic components of the excitation signal, but when an external magnetic field is applied, even harmonics are generated. The wave component comes to appear, and the signal level of this even harmonic component is detected by the detection coil 2.
It changes in proportion to the magnitude of the magnetic field component of the external magnetic field orthogonal to 7, 28. Therefore, the outputs of the detection coils 27 and 28 are harmonic detection circuits 3 for detecting even harmonic components.
Was added to 1, 32 is proportional to the magnitude of the even-order harmonic component DC voltage e _x, detects e _y, the arithmetic circuit 34 through a correction calculation circuit 33,

[0040]

[Equation 6] The traveling direction θ of the vehicle is calculated and output by the calculation. It should be noted that other circuit parts including the traveling sensor 3, the distance counter 4, the arithmetic unit 5, the keyboard 6 and the display 7 are shown in FIGS.
Will be the same as

The correction operation circuit 33 inputs the respective detection voltages e _x, e _y than harmonics detection circuits 31 and 32 has a circuit configuration shown removed in FIG. 11, the detection voltage e _x, e
_As shown in the signal vector diagram of FIG. 12, _y represents the signal voltage in the X and Y axis directions of the combined vector C of the signal vector A due to the vehicle magnetism and the signal vector B due to the geomagnetism, so the center of rotation of the signal vector B The equation of the circle with radius e _R (size of signal vector B) about the signal voltage (e _xo , e _yo )

[0042]

[Equation 7] Given in. Therefore, in the calculator 35, the detection voltages e _x , at at least two arbitrary points on the circumference of FIG.
By solving the simultaneous equations of Equation 7 based on e _y , the signal voltages e _xo and e _yo representing the magnitude of the signal vector A that is the center of rotation are output.

Calculation outputs e _xo and e _yo from the calculator 35
Are subtracted from the detected voltages e _x and e _y from the harmonic detection circuits 31 and 32, respectively, as a result of being input to the subtractors 36 and 37. The detected voltages e _x and e _y representing only the signal vector B (see FIG. 11) are output, and the traveling direction θ of the vehicle is calculated in the calculator 34 based on the equation (6).

FIG. 13 is a block diagram showing a third embodiment using the non-rotational direction sensor 25. In this embodiment, the detection voltages e _x and e _y of the harmonic wave detection circuits 31 and 32 are shown.
The correction voltages e _xo and e calculated by the calculator 35 based on
Each of _yo is fed back to the input side of the harmonic detection circuits 31 and 32 as a negative voltage, and the harmonic detection circuit 3
The signal component due to the vehicle body magnetism contained in the detection voltage from the direction sensor 25 input to 1, 32 is directly corrected.

Regarding the correction calculation of the geomagnetism detection signal in the embodiment shown in FIGS. 10 and 13, as in the embodiment shown in FIG. Based on this, the error signal component due to the vehicle magnetism included in the geomagnetic detection signal is corrected.

[0046]

As described above, according to the present invention, a direction sensor for detecting a geomagnetic vector that is a combination of the geomagnetism and the vehicle body magnetism, and the direction sensor when the direction sensor faces at least two traveling directions of the vehicle. Vector detection means for detecting a geomagnetic vector, storage means for storing the magnitude of the geomagnetism in advance, magnetism of the vehicle body based on the geomagnetic vectors in the at least two vehicle traveling directions and the magnitude of the geomagnetism stored in the storage means. Since the vehicle body magnetic vector calculating means for calculating the vehicle body magnetic vector represented and the correcting means for correcting the geomagnetic vector of the direction sensor based on the vehicle body magnetic vector are provided, the vehicle body magnetism vector can be appropriately adjusted even if the vehicle body magnetism changes. By correcting, the detection error of the direction sensor due to the vehicle body magnetism can be corrected almost completely, and a highly accurate drive guide is possible. It has the effect of making.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of an error detection circuit in the embodiment of FIG.

FIG. 3 is a vector diagram showing a normal case of a geomagnetism detection signal.

FIG. 4 is a vector diagram showing a case where the geomagnetic detection signal is abnormal.

FIG. 5 is a block diagram showing a first embodiment for correcting an error due to vehicle body magnetism.

6 is a block diagram showing an embodiment of a correction arithmetic circuit in FIG.

FIG. 7 is a signal vector diagram showing the operation of correction calculation.

8 is a block diagram showing an example of a specific configuration of the arithmetic unit of FIG.

9 is a signal waveform diagram showing correction of the geomagnetic detection signal in the embodiment of FIG.

FIG. 10 is a block diagram showing a second embodiment using a non-rotational direction sensor.

11 is a block diagram showing an example of a specific configuration of the correction arithmetic circuit of FIG.

FIG. 12 is a signal vector diagram for explaining the correction calculation in FIG.

FIG. 13 is a block diagram showing a third embodiment using a non-rotational direction sensor.

[Explanation of symbols]

 Es Geomagnetic vector signal 1 Direction sensor 13 Storage circuit 16 Correction means (correction calculation circuit) 20 Body magnetic vector calculation means

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[Procedure amendment]

[Submission date] April 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described. First, when a vehicle having a signal vector obtained by the magnitude and phase difference of the geomagnetic detection signal Es with respect to the reference signal Er output from the direction sensor 1 is placed at the same point, for example, on a turntable and rotated once, a trajectory is drawn as shown in FIG. It is expressed as. In FIG. 3, the signal vector C is the direction sensor 1.
This is a geomagnetic detection signal Es output from the signal vector C, which is a signal vector A having a predetermined phase difference with respect to the reference signal Er due to vehicle body magnetism and a signal vector B due to the original geomagnetism in the traveling direction of the vehicle. Given as a composite vector. Therefore, in the embodiment of FIGS. 1 and 2,
For example, as shown in the signal vector of FIG. 3, the reference signal Er
Geomagnetic detection signal Es obtained when the vehicle is oriented in a predetermined direction in which the phase difference of the geomagnetic detection signal Es with respect to is θ _0.
Signal level, that is, the magnitude S ₀ of the signal vector C is stored in the storage circuit 13 together with the phase difference θ ₀ . Well
Also, in FIG. 3, what is indicated by a broken line is a signal vector.
Shows the case where C is in a direction different from the above predetermined direction
Is. In any case, the geomagnetic signal vector B
It can be seen that is constant in any direction. This
Therefore, the signal vector C stored in the storage circuit 13 is
The magnitude S ₀ and the phase difference θ ₀ of which the signal vector B is
The signal vector A is
Even though it remembers the magnitude and direction of the indicated body magnet
Good

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029]

[Equation 3] Therefore, at least two points on the circumference of the signal vector C , for example, two points of (x ₁ , y ₁ ) and (x ₂ , y ₂ ) are centered and

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

In addition, in order to remove the influence of noise and the like in the calculation of Expression 4, in practice , the calculation at the above-mentioned two points is performed a plurality of times (that is, three or more directions) and the calculation is performed (x ₀ ,
It is desirable to find the average value of y ₀ ). From the value of (x ₀ , y ₀ ) thus obtained, the signal level S ₀ and the phase difference θ ₀ of the signal vector A due to the vehicle body magnetism are obtained.
To

Claims (3)

[Claims] 1. A direction sensor that detects a geomagnetic vector that is a combination of geomagnetism and vehicle body magnetism, vector detection means that detects the geomagnetic vector when the direction sensor faces at least two vehicle traveling directions, and Storage means for storing a magnitude in advance; vehicle body magnetic vector calculation means for calculating a vehicle body magnetic vector representing the magnetism of the vehicle body from the geomagnetic vectors in the at least two vehicle traveling directions and the magnitude of the geomagnetism stored in the storage means; And a correction unit that corrects the geomagnetic vector of the direction sensor based on the vehicle body magnetic vector. 2. A direction sensor for detecting a geomagnetic vector that is a combination of geomagnetism and vehicle body magnetism, vector detecting means for detecting the geomagnetic vector when the direction sensor faces at least two vehicle traveling directions, and Storage means for storing the magnitude in advance, for each geomagnetic vector detected by the vector detection means, a circle having the radius of the magnitude of the geomagnetism centered on the coordinates of the end of the geomagnetic vector is obtained and the intersection of the circles is obtained. Coordinate calculation means for obtaining coordinates, vehicle body magnetic vector calculation means for calculating a vehicle body magnetic vector from the coordinates of the start point of the geomagnetic vector and the intersection coordinates obtained by the coordinate calculation means, and the geomagnetic vector of the direction sensor as the vehicle body magnetic vector. A vehicle azimuth detecting device, comprising: 3. A direction sensor that detects a geomagnetic vector that is a combination of geomagnetism and vehicle body magnetism, a vector detecting unit that detects the geomagnetic vector when the direction sensor faces a plurality of vehicle traveling directions, and a magnitude of the geomagnetism. And a storage means for storing the height in advance, for each pair of geomagnetic vectors detected by the vector detection means, a circle having the radius of the magnitude of the geomagnetism with the coordinates of the coordinates of the end of the geomagnetic vector as the center point is obtained. Coordinate calculation means for obtaining the intersection coordinates, average coordinate calculation means for obtaining the average coordinates of the plurality of intersection coordinates obtained for each of the pair of geomagnetic vectors by the coordinate calculation means, coordinates of the start point of the geomagnetic vector and the average coordinate calculation A vehicle body magnetic vector calculation means for calculating a vehicle body magnetic vector from the average coordinates obtained by the means; A vehicle azimuth detecting device, comprising: a correcting unit that corrects based on a magnetic vector.