JP2006275524A - Electronic azimuth meter and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic azimuth meter capable of acquiring a true bearing by detecting a change of a polarization state, namely, a change of offset, and by re-acquiring and correcting the offset only at that time. <P>SOLUTION: This electronic azimuth meter is constituted of a magnetometric sensor, an xyz-offset acquisition device for operating the offset, a bearing calculation device for operating the bearing from the magnetometric sensor output and an offset output, a storage device for storing an xyz-three dimensional coordinate value, an xyz-offset value and an output equivalent to geomagnetism, and a geomagnetism quantity determination device for detecting existence of a change of the output equivalent to the geomagnetism and outputting the result. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic azimuth meter and a recording medium for measuring an azimuth using a magnetic sensor. In particular, the present invention relates to an electronic azimuth meter capable of performing offset correction when an offset other than geomagnetism (xyz offset value) occurs due to the influence of magnetization of peripheral equipment under an arbitrary tilt environment, and a recording medium used for the electronic azimuth meter.

  The electronic azimuth meter has a feature that the azimuth can be electrically displayed using a sensor or the like. In general, an electronic azimuth meter is configured by arranging a plurality of magnetic sensors. A magnetic sensor exhibits a linear output for a magnetic field parallel (or perpendicular) to the sensor. Therefore, the azimuth angle from the direction determined as the reference can be calculated by calculating the data obtained from the outputs of the plurality of magnetic sensors arranged orthogonally. Since the azimuth obtained from this azimuth can be processed as an analog or digital electrical signal, a portable information terminal such as a mobile phone or PDA, a wristwatch, a car navigation device as a vehicle azimuth meter, an attitude detection of an aircraft, a visually impaired person Application to various electronic devices such as a game machine is expected.

  In particular, in recent years, position information providing services for portable information terminals using GPS or the like have begun. According to this service, the user can understand the current position information while looking at the screen on the terminal. By combining this terminal with an electronic compass, it is possible to determine which direction the user is currently facing, or where he is going if he is walking. This information providing service regarding position information and electronic compass is expected to create new business for many industries in the future, and will also provide useful information to users. As such services progress, it is inevitable that the issues required for electronic compass will be higher quality and higher accuracy.

  The improvement in quality and accuracy required for the above-mentioned electronic compass indicates that the azimuth is measured more accurately, but the azimuth cannot be calculated accurately due to the influence of magnetization of peripheral devices of the magnetic sensor. Sometimes. When the magnetic sensor generates only an output corresponding to geomagnetism, the direction can be accurately calculated. However, when components or machines around the magnetic sensor are magnetized, an offset is added to the output voltage of the magnetic sensor, and an output corresponding to the amount of geomagnetism cannot be obtained.

  The above contents will be described with reference to FIG. FIG. 5 is a diagram showing the relationship among the total magnetic vector 301, the offset vector 302, and the geomagnetic vector 303. The coordinate axes in this drawing indicate the outputs of the magnetic sensors of the xyz axes, and in which direction the total magnetic vector 301, the offset vector 302, and the geomagnetic vector 303 are oriented with respect to the arrangement of the magnetic sensors. It expresses how big it is.

The total magnetic vector 301 shown in this drawing represents a vector derived from the output of the x, y, and z axis magnetic sensors, and the xyz three-dimensional coordinate value 304 (x _s , y _s , z _s ) corresponds thereto. The offset vector 302 represents a vector derived from the offset output of each of the x-, y-, and z-axes due to the magnetization of the peripheral device and the influence of the circuit, and the xyz offset value 305 (x _offs , y _offs , z _offs ). Equivalent to. A geomagnetism vector 303 represents a vector derived from an output generated by each magnetic sensor due to the influence of geomagnetism, which corresponds to an output value 306 (x _H , y _H , z _H ) corresponding to geomagnetism.

In order to obtain an azimuth angle using the configuration requirements shown in this drawing, it is necessary to perform calculations using output values 306 (x _H , y _H , z _H ) derived only from geomagnetic output. This (x _H , y _H , z _H ) is obtained by dividing the xyz offset value 305 (x _offs , y _offs , z _offs ) from the xyz three-dimensional coordinate value 304 (x _s , y _s , z _s ). However, it is necessary to know the xyz offset value 305 which is an influence of magnetization of the peripheral device by some method.

  Therefore, a magnetic field vector detection method has been disclosed as a conventional magnetization correction method that can eliminate the influence of offset errors even when they occur (see, for example, Patent Document 1).

  This method is a method of calculating an offset from an output value when a magnetic sensor arranged in three dimensions is arbitrarily changed in at least four directions.

FIG. 6 shows the basic concept of the present invention.
If the offset vector 302 is constant, that is, under an environment where the influence of magnetization of peripheral devices is constant, the total magnetic vector 301 when the azimuth and the tilt angle are changed is centered on the offset vector 302 and the magnitude of the geomagnetic vector 303. The top of the sphere with the radius as the radius is shown. The center point of the sphere is calculated from the four points on the sphere, so that the xyz offset value 305 of the center point can be obtained from the output of the four points whose directions are arbitrarily changed. Furthermore, according to this method, even when the magnetization amount of the peripheral device changes with time, the xyz offset value 305 relating to magnetization can be acquired each time, and the xyz three-dimensional coordinate value shown in FIG. The target output value 306 is obtained based on 304 and the xyz offset value 305, and the orientation can be displayed on the electronic compass.

Japanese Patent Publication No.3-3190 (page 3, Fig. 2)

  However, the electronic azimuth meter based on the means described in Patent Document 1 does not detect a change in magnetization itself. Therefore, there is a problem that the user of the electronic azimuth meter does not know whether the currently displayed azimuth indicates a true azimuth or whether correction is in progress.

  In addition, in this conventional electronic azimuth meter, since this xyz offset value 305 is constantly updated, the amount of calculation until the azimuth is calculated increases, and as a result, the azimuth is output or the azimuth obtained here is calculated. There was a problem that it took time to display.

  Furthermore, depending on how the data in the four directions are taken, there is a problem that the xyz offset value 305 cannot be obtained accurately, and thus the azimuth cannot be calculated accurately.

  Therefore, the present invention solves the above-described problems, detects a change in magnetization state, that is, a change in xyz offset value, and re-acquires the xyz offset value only when the xyz offset value changes. It is an object of the present invention to provide an electronic azimuth meter capable of obtaining a true azimuth by correcting the azimuth and a recording medium used for the electronic azimuth meter.

  In order to solve the above problems, the electronic azimuth meter of the present invention and the recording medium used for the electronic azimuth meter basically adopt the following forms.

The electronic compass according to the present invention has an output value x corresponding to a magnetic vector in the xyz-axis direction.
a magnetic sensor that acquires a yz three-dimensional coordinate value, an xyz offset acquisition device that acquires an xyz offset value resulting from an output other than geomagnetism, and an azimuth calculation device that calculates an azimuth using the xyz three-dimensional coordinate value and the xyz offset value , Xyz three-dimensional coordinate value, xyz offset value and output corresponding to geomagnetism, the current output value corresponding to geomagnetism and the output value corresponding to geomagnetism acquired in the past, And a geomagnetism determining device that detects and outputs a corresponding output change.

  Further, the electronic azimuth meter according to the present invention resets the xyz offset value when the above-described xyz offset acquisition device recognizes an output change larger than a predetermined change amount as a result of being output from the geomagnetism determination device. It further has the function to acquire.

The electronic azimuth meter according to the present invention includes a tilt sensor having a function of acquiring a pitch angle β _g formed by the x-axis and the horizontal plane and an output of a tilt angle corresponding to the roll angle α _g formed by the y-axis and the horizontal plane. Further, the azimuth calculation device further includes a function of calculating the azimuth based on the xyz three-dimensional coordinate value, the xyz offset value, and the tilt angle.

  The recording medium according to the present invention acquires magnetic vector acquisition means for acquiring an xyz three-dimensional coordinate value, which is an output value corresponding to a magnetic vector in the xyz axis direction, from a magnetic sensor, and an xyz offset value resulting from an output other than geomagnetism. xyz offset acquisition means, azimuth calculation means for calculating the azimuth using the xyz three-dimensional coordinate value and the xyz offset value, storage means for storing the xyz three-dimensional coordinate value, the xyz offset value, and an output corresponding to geomagnetism, The present invention has a geomagnetism determining means that compares a current output value corresponding to geomagnetism with an output value corresponding to geomagnetism acquired in the past, detects whether there is a change in output corresponding to geomagnetism, and outputs it. It is what.

  Further, the recording medium according to the present invention has an xyz offset value when the xyz offset acquisition unit described above receives a result of comparison by the geomagnetic amount determination unit and an output change larger than a predetermined change amount is recognized. It has a function of recalculating and updating the xyz offset value.

  In the recording medium according to the present invention, the xyz offset acquisition unit described above further has a function of acquiring four or more different xyz three-dimensional coordinate values from a plurality of xyz three-dimensional coordinate values acquired by the storage unit. It is characterized by.

を満たすことを特徴とするものである。 In addition, the recording medium according to the present invention includes xyz three-dimensional coordinate values (x _si , y _si , z _si ) serving as reference values and xyz three-dimensional coordinate values (x _sj , y _sj , z _sj ) for comparison with the reference values. ) With respect to preset allowable values δ _x , δ _y , δ _z

It is characterized by satisfying.

The recording medium according to the present invention further includes a pitch angle beta _g formed in the x-axis and the horizontal plane, the inclination angle obtaining means for obtaining an output of the tilt angle corresponding to make the roll angle alpha _g of y-axis and the horizontal plane The azimuth calculating means has a function of calculating the azimuth based on the xyz three-dimensional coordinate value, the xyz offset value, and the tilt angle.

  The recording medium according to the present invention further has a function in which the xyz offset acquisition unit described above acquires four or more different xyz three-dimensional coordinate values from a plurality of xyz three-dimensional coordinate values acquired by the storage unit. The storage means has a function of storing an inclination angle in correlation with the xyz three-dimensional coordinate value together with an xyz three-dimensional coordinate value, an xyz offset value, and an output value corresponding to geomagnetism.

を満たすように相異なる４点以上のｘｙｚ３次元座標値を取得することを特徴とするものである。 The recording medium according to the present invention, in xyz offset acquisition unit described above, the inclination angle (α _gi, β _gi) and tilt angle (α _gj, β _gj) relationship with is preset allowable value lambda _alpha , Λ _β

It is characterized in that four or more different xyz three-dimensional coordinate values are acquired so as to satisfy the above.

を満たすことを特徴とするものである。 The recording medium according to the present invention includes xyz three-dimensional coordinate values (x _si , y _si , z _si ) serving as reference values and xyz three-dimensional coordinate values (x _sj , y _sj , z _sj ) for comparison with the reference values. ) With respect to preset allowable values δ _x , δ _y , δ _z

It is characterized by satisfying.

  As described above, in the electronic azimuth meter of the present invention and the recording medium using the electronic azimuth meter, the offset is acquired using four or more xyz three-dimensional coordinate values acquired by the magnetic sensor. In the offset acquisition, the current and past geomagnetism are compared to detect a change in the magnetized state, that is, a change in the offset, and the offset is acquired again only at that time. Therefore, there is an advantage that the amount of calculation until the azimuth is calculated does not increase, and as a result, no time is required to output or display the azimuth.

  Furthermore, in order to obtain the four or more xyz three-dimensional coordinate values, coordinate values as far as possible are selected from a plurality of stored xyz three-dimensional coordinate values. That is, by selecting coordinate values of points on the spherical surface as far as possible, the accuracy of the offset value can be improved, and as a result, a true orientation can be obtained.

  According to the present invention, the user of the electronic azimuth meter can know information whether the azimuth currently displayed in an arbitrary tilt environment indicates a true azimuth, or whether correction is in progress. become.

  In addition, since it is possible to detect the change of the magnetization state, that is, the change of the offset, and correct the orientation by re-acquiring the xyz offset value only at that time, the user of the electronic compass is always accurate. It is possible to obtain a simple orientation.

  An electronic azimuth meter of the present invention and a recording medium used for the electronic azimuth meter include a magnetic sensor, an xyz offset acquisition device for acquiring an xyz offset value, and an azimuth calculation for calculating an azimuth from the magnetic sensor output and the offset output. Basically, a device, a storage device for storing xyz three-dimensional coordinate values, an xyz offset value, and an output corresponding to geomagnetism, and a geomagnetism determination device that detects and outputs a change in output corresponding to geomagnetism. Configured.

First, the geomagnetism determination device that is the point of the present invention will be described below.
After acquiring an output value corresponding to the current geomagnetism, this geomagnetism determination device compares the output value corresponding to the geomagnetism acquired in the past and detects whether there is a change in the output corresponding to the geomagnetism and outputs it. It has the function to do. According to this method, changes in offsets other than geomagnetism can be known, and the xyz offset value is acquired as necessary, so the amount of calculation before calculating the direction does not increase, and as a result, the direction is output. Or it does not take time to display.

Specifically, first from the magnetic sensor xyz3 dimensional coordinate values _{(x s, y s, z} s) to acquire. Since the xyz three-dimensional coordinate value corresponds to a combined vector of the geomagnetic vector and the offset vector, the geomagnetism is obtained using the xyz three-dimensional coordinate value and the already stored xyz offset values (x _offs , y _offs , z _offs ). The magnitude of the geomagnetic vector corresponding to the quantity (output value S _h ) can be obtained. Specifically, the calculation is performed by the following equation (1).

上記式（２）により、演算された値が許容値の範囲内、すなわち式（２）を満たさなければ、周辺機器の着磁状態などの変化がないと判断し、先に取得したｘｙｚオフセット値をそのまま用いて方位演算とその演算結果を出力或いは表示する。逆に、上記式（２）により、演算された値が許容値の範囲外、すなわち式（２）を満たせば、周辺機器の着磁状態などの変化が認められたと判断し、その情報を出力或いは表示する。更に、その地磁気量判定装置の出力に基づき、ｘｙｚオフセット値を再取得し、正しいｘｙｚオフセット値を用いて方位演算を行う様にすれば、常に真の方位角を得ることが可能となる。またｘｙｚオフセット値の取得を行っている間は、ｘｙｚオフセット値の取得が進行中である旨の情報を出力或いは表示するようにしても良い。 Then, the numerical value of the past output value S _h ′ calculated by the above equation (1) is compared with the latest calculated output value S _h, and it is larger or smaller than a preset allowable value. Compare and judge. As a specific method for comparing the permissible values, for example, it can be determined whether or not the following equation (2) is satisfied.

According to the above equation (2), if the calculated value does not satisfy the range of the allowable value, that is, if the equation (2) is not satisfied, it is determined that there is no change in the magnetization state of the peripheral device, and the xyz offset value acquired earlier. Is used as it is to output or display the azimuth calculation and the calculation result. On the other hand, if the calculated value is out of the allowable range according to the above equation (2), that is, if the equation (2) is satisfied, it is determined that a change in the magnetization state of the peripheral device is recognized, and the information is output. Or display. Furthermore, if the xyz offset value is reacquired based on the output of the geomagnetism determination device and the azimuth calculation is performed using the correct xyz offset value, a true azimuth angle can always be obtained. Further, during the acquisition of the xyz offset value, information indicating that the acquisition of the xyz offset value is in progress may be output or displayed.

Then, the xyz offset value _{(x offs, y offs, z} offs) and the acquisition result of the output value _{S h} corresponding to the geomagnetic amount, not only azimuth calculation, for use as a numerical value when performing the next comparison Stored in the storage device. In this xyz offset value is reacquired value itself, the output value S _h corresponding to geomagnetic utilizes one of the data of four points using its xyz offset value and the offset acquired geomagnetism The output corresponding to the quantity is calculated.

  Further, while the data necessary for obtaining the above xyz offset value is available, the azimuth may be calculated using the previous xyz offset value. If the azimuth is calculated using the previous xyz offset value, an error occurs from the true azimuth. However, the time required to acquire four points of data does not require much time, so that it is practically used. It is not a big problem.

  With the above configuration, the user of the electronic azimuth meter of the present invention has information such as whether the currently displayed azimuth indicates a true azimuth or in the middle of correction under an arbitrary tilt environment. It becomes possible to understand, and it becomes possible to use the electronic compass in peace. Furthermore, if the electronic azimuth meter of the present invention is used, a change in the magnetization state, that is, a change in offset can be detected, and only at that time, an xyz offset value can be reacquired and corrected. Therefore, the calculation amount until the calculation of azimuth is not increased, and as a result, it is possible to adopt a form that does not require time to output or display the azimuth.

Here, the first embodiment of the electronic compass of the present invention will be described.
FIG. 1 is a diagram showing a block configuration of an electronic azimuth meter in Embodiment 1 of the present invention, and FIG. 2 is a diagram showing a flowchart of azimuth calculation in a recording medium used in the electronic azimuth meter of the present invention.

As shown in FIG. 1, the electronic azimuth meter 2 a includes a magnetic sensor 4, a geomagnetic amount determination device 8, a storage device 10, an xyz offset acquisition device 12, and an azimuth calculation device 14. The magnetic sensor 4 is composed of an x-axis, y-axis, and z-axis magnetic sensor, and can obtain all magnetic vectors by taking out outputs in the respective axial directions. The storage device 10 includes a plurality of xyz three-dimensional coordinate values (x _Si , y _Si , z _Si ) (i = 1 to 4), which are outputs corresponding to magnetic vectors, and xyz offset values (x _offs , y _offs , z having a _offs), the output value corresponding to a geomagnetism _{(x H,} y _H, a function of storing an output value _{S h} indicating the magnitude of the magnetic vector obtained from _{z H),} respectively. The xyz offset acquisition device 12 has a function of calculating an xyz offset value using four different xyz three-dimensional coordinate values from the xyz three-dimensional coordinate value stored in the storage device 10. The azimuth calculation device 14 calculates the azimuth using the xyz offset value and the xyz three-dimensional coordinate value.

  Next, the recording medium used in the electronic azimuth meter 2a of the present invention will be described with reference to FIG.

First, an xyz three-dimensional coordinate value (x _s , y _s , z _s ), which is an output value corresponding to a magnetic vector in the xyz axis direction, is acquired from the magnetic sensor 4 by the magnetic vector acquisition means (S2). The xyz three-dimensional coordinate value is a combination of the output corresponding to the xyz offset value influenced by the magnetism and the circuit of the peripheral device and the output corresponding to the geomagnetism as described above. Since the output of the magnetic sensor 4 includes noise or the like and may contain an error, a stable output can be obtained by adding a process that averages some of the acquired data. It is preferable.

Then, the xyz three-dimensional coordinate value obtained above is stored in the storage device 10 (see FIG. 1) in the first storage means (S4). A rewritable RAM is preferably used as the storage device 10 and data is sequentially written over time. When the RAM capacity is filled, data is rewritten in order from the oldest one so that the latest data is always left in the RAM. Note that if the data capacity is too small, the number of the latest data decreases, and effective data for offset calculation may not be obtained. Therefore, it is desirable to have a certain capacity.

Next, the geomagnetism determining means (S6) obtains xyz three-dimensional coordinate values (x _s , y _s , z _s ) from the magnetic sensor 4 as described above, and the magnitude of the geomagnetic vector corresponding to the geomagnetism. (Output value S _h ) is obtained. And it compares with the magnitude | size (output value S _h ') of the geomagnetic vector acquired in the past. As a result of the comparison, if the amount of change is smaller than the predetermined change amount, the azimuth calculation means (S8) is performed using the previous xyz offset value. If an output change larger than the predetermined change amount is recognized, the xyz offset value is recalculated to update the xyz offset value.

Here, a method for specifically updating the xyz offset value will be described below.
First, in the data acquisition means in the xyz offset acquisition means (S10), four points of three-dimensional coordinate values (x _Si , y _Si , z _Si ) (i = 1 to 4) from the data stored in the storage device 10 described above. Retrieve the data. These four points of data must be selected so as to have different values. In other words, the accuracy of the xyz offset value obtained here can be further increased by selecting the one located as far as possible on the spherical surface of the sphere centered on the xyz offset value serving as the reference value described above. It becomes like this.

More specifically, for the first three-dimensional coordinate value (x _si , y _si , z _si ) serving as the reference value, the three-dimensional data serving as data to be compared with the reference value from the next second point. A difference between coordinate values (x _sj , y _sj , z _sj ) is calculated, and data whose values exceed a preset allowable value is selected. For example, when it is desired to select and set data in which the outputs of the x-axis, y-axis, and z-axis magnetic sensors are separated by allowable values δ _x , δ _y , and δ _z [mV], respectively, the following equations (3) (4 ) The reference is set as in (5), and the four magnetic sensor outputs satisfying this condition are acquired.

Note that if the allowable values δ _x , δ _y , and δ _z are too small, the xyz offset value may not be obtained accurately. Conversely, if the allowable values δ _x , δ _y , δ _z are too large, it takes time to acquire data. Therefore, it is desirable to set the allowable values δ _x , δ _y , and δ _z to predetermined values in advance according to the application in which the electronic azimuth meter 2a of the present invention is used. In the arithmetic processing of the electronic azimuth meter 2a of the present invention, it is not always necessary to satisfy all of the expressions (3), (4), and (5), and any one of them may be satisfied.

  In this way, before the external influence of the measurement environment of the magnetic sensor 4 changes, the three-dimensional coordinates of four different points when the orientation and inclination of each magnetic sensor 4 arranged on the xyz axis are changed. You will be able to get the value.

Further, the offset computing device in the xyz offset obtaining means (S10) computes and obtains an xyz offset value. This will be specifically described below using mathematical expressions.
First, the four points data, output values _{S h} and xyz offset value corresponding to a geomagnetism When _{(x offs, y offs, z} offs) and is one that was acquired in the same conditions, the number of data number as i When attached to a subscript, they can be expressed by the following relational expressions (6) and (7), respectively.

The right side in the above equation (6) is an operation determined by all the output values obtained by the magnetic sensor 4, and the four different xyz three-dimensional coordinate values obtained by the magnetic sensor 4 are substituted into the above equation (6). By doing so, it becomes possible to acquire xyz offset values ( _xoffs , _yoffs , _zoffs ).

The numerical value at the time of performing previously obtained xyz offset value _{(x offs, y offs, z} offs) and the acquisition result of the output value _{S h} corresponding to the geomagnetic amount, not only azimuth calculation, the next comparison Therefore, the data in the storage device 10 is updated by the second storage means (S12). Xyz offset value stored here, a re-obtained value itself, the output value S _h corresponding to geomagnetic utilizes one of the data of four points using its offset value and the offset acquisition , to that calculated output value S _h corresponding to geomagnetic.

Next, the azimuth calculation means (S8) will be described.
In the azimuth calculation means (S8), the three-dimensional coordinate values (x _s , y _s , z _s ) acquired by the magnetic vector acquisition means (S2) and the xyz offset value (x x) obtained by the offset acquisition means (S10). azimuth is calculated using " _offs , _yoffs , _zoffs )". In this embodiment, it uses a magnetic sensor 4 of the 3-axis, the tilt correction, taking into account the state of the pitch angle beta _g tilt only x-axis is observed axis, employs means for calculating converted horizontally did. In the system described above, the output value from the geomagnetic magnetic sensor _{4 (x H, y H,} z H) , the output value S _h which corresponds to the total geomagnetic _amount, the pitch angle beta _g, azimuth theta, and geomagnetic It is expressed by the following relational expression (8) using the dip angle I.

By developing the relational expression (8), the following relational expression (9) relating to the azimuth angle θ is obtained, and the xyz three-dimensional coordinate values and xyz stored in the magnetic vector acquisition means (S2) and the storage means (S4) are obtained. The azimuth angle θ can be obtained using the offset value.

Here, the dip angle I can also be acquired using GPS position information or the like. Specifically, the latitude φ and longitude λ of the measurement position are acquired, and the dip angle value I at that location is calculated and output. The dip angle value I in various parts of Japan can be approximated by the following quadratic expression (15).

In addition, since the dip angle value I calculated here is a positive value, it is a negative value when substituting it into the equation (13) or the like. As described above, an angle corresponding to the pitch angle β _g (= rotation angle β) can be obtained from the magnetic sensor output by these means.

As described above, the output value (x _H , y _H , z _H ) derived from the geomagnetism of the magnetic sensor 4 is derived from the sensor output of the xyz three-dimensional coordinate value (x _S , y _S , z _S ) by the xyz offset value (x _(offs , _yoffs , _zoffs ) can be obtained as a difference. Therefore, in order to calculate an accurate output value (x _H , y _H , z _H ), an accurate xyz offset value needs to be acquired, and the offset acquisition method of this embodiment is effective. In addition, the electronic azimuth meter 2a can be provided so that the wrong azimuth is not shown as much as possible.

  As described above, according to the configuration of the present embodiment, the user of the electronic azimuth meter 2a using the three-axis magnetic sensor can determine whether or not the offset correction is performed by the geomagnetic amount determination means. It can be used with confidence. Furthermore, the electronic azimuth meter 2a of the present invention can detect a change in the magnetized state, that is, a change in the offset, and can only acquire and correct the xyz offset value only at that time, and always updates the offset. Since it is not necessary, the amount of calculation until the azimuth is calculated does not increase, and as a result, no time is required to output or display the azimuth.

In addition, the xyz offset value may not be obtained accurately depending on how the data in the four directions are taken, but the xyz offset acquisition means of the present invention should be devised to acquire four points of data. Thus, an accurate xyz offset value can be acquired. Therefore, the user of the electronic azimuth meter 2a can automatically know an accurate azimuth.

Next, a second embodiment of the electronic azimuth meter of the present invention will be described.
FIG. 3 is a diagram showing a block configuration of the electronic compass in the second embodiment of the present invention, and FIG. 4 is a flowchart for explaining each step until obtaining an azimuth using the block configuration shown in FIG. is there.

The block configuration of the electronic azimuth meter 2b in the present embodiment is basically the same as that in FIG. 1, except that a tilt sensor 6 having an x-axis tilt sensor and a y-axis tilt sensor is newly added. This is different from the first embodiment. In addition, the storage device 10 in this embodiment has a function of storing not only the output of the magnetic sensor 4 but also the output (α _gi , β _gi ) of the tilt sensor 6 serving as a reference value. The xyz offset acquisition device 12 further has a function of acquiring, from the storage device 10, four points of data with different outputs of the magnetic sensor 4 based on the stored output of the tilt sensor 6. In addition, since the other component requirements of the electronic azimuth meter 2b in the present embodiment are the same as those in the first embodiment as described above, description thereof is omitted here.

Next, the recording medium used for the electronic azimuth meter 2b of the present invention in this embodiment will be described with reference to the flowchart of FIG.
The magnetic vector acquisition means (S2) shown in this flowchart is performed in the same manner as in the first embodiment. Then, at a tilt angle acquisition means (S14), the roll angle alpha _g formed by the pitch angle beta _g and the y-axis and the horizontal plane form the x-axis and the horizontal plane is obtained from the inclination sensor 6. When an acceleration sensor is used as the tilt sensor 6, an output proportional to the magnitude of gravitational acceleration in each axial direction can be obtained. Since the output of these sensors includes noise and may contain errors, a more stable output can be obtained by storing a plurality of data in advance and adding a process that averages these data. You will be able to get

  Next, the first storage means (S4) stores the magnetic sensor output obtained by the magnetic vector acquisition means (S2) and the inclination angle acquisition means (S12) in correspondence with the inclination angle. A rewritable RAM may be used for the storage device 10 as in the first embodiment, and data is sequentially written over time.

  Further, xyz offset acquisition means (S10) acquires four different magnetic sensor output data from the data stored in the storage device 10. Note that this means does not acquire any value, but acquires only necessary data after selecting different tilt angles stored at the same time as the magnetic sensor output. Is preferred.

Specifically, the difference between the roll angle α _gi and the pitch angle β _gi to be compared with the reference value is calculated for the first point data serving as the reference value, and the preset allowable value is calculated. If it exceeds, select the data. For example, when it is desired to select and set data in which the output of the roll angle α _gj and the pitch angle β _gj are different from each other by the allowable values λ _α and λ _β [deg], the reference is expressed by the following equations (18) and (19). The four-point magnetic sensor outputs having the inclination angles α _g and β _g satisfying this condition are obtained.

If the allowable values λ _α and λ _β are too small, an accurate xyz offset value may not be obtained. Conversely, if the allowable values λ _α and λ _β are too large, it takes time to acquire data. Therefore, it is desirable to set the permissible values λ _α and λ _β to predetermined values according to the application in which the electronic azimuth meter 2b is used. It should be noted that the above-mentioned conditions with different inclination angles are added when considering the above xyz three-dimensional system, when four points of data exist on a circle formed by the intersection of a sphere and an arbitrary plane. It is because it corresponds. This corresponds to the case where four points of data are acquired in the state where the roll α _g angle and the pitch angle β _g are the same, and therefore different under different conditions as in this embodiment. By acquiring four points of data, it is possible to acquire an accurate xyz offset value.

The data acquired here is calculated by an xyz offset acquisition means (S10), and an xyz offset value ( _xoffs , _yoffs , _zoffs ) can be acquired. The specific method is the same as in the first embodiment, and the description here is omitted. Then, similarly to the second storage means (S12) also Example 1, xyz offset value _{(x offs, y offs, z} offs) and, by updating the acquisition results of the output values _{S h} corresponding to geomagnetic storage Store in device 10.

Then, in the azimuth calculation means (S8), the three-dimensional coordinate values (x _s , y _s , z _s ) acquired by the magnetic vector acquisition means (S2) and the offset (x10) obtained by the xyz offset acquisition means (S10) x _offs , y _offs , z _offs ), and the roll angle α _g and pitch angle β _g obtained by the tilt angle acquisition means (S4), the azimuth is calculated. Thus, in the electronic compass 2b shown in this embodiment, a triaxial magnetic sensor and a biaxial tilt sensor are used, and a means for calculating by correcting the tilt is adopted. Therefore, in the above system, the magnetic sensor The output value (x _H , y _H , z _H ) derived from the geomagnetism of 4 is expressed by the following relational expression (20) using the output value S _h corresponding to the total geomagnetism, the dip angles I, α, β, and the azimuth angle θ. ).

さらに、上記の式（２１）に、磁気ベクトル取得手段（Ｓ２）で得られたｘｙｚ３次元座標値、傾斜角取得手段（Ｓ１２）で得られたロール角α_ｇ、ピッチ角β_ｇ、記憶手段（Ｓ４）で記憶されたとｘｙｚオフセット値をそれぞれ代入して、目的の方位角θを得ることができる。 Then, by developing the relational expression (20), the following relational expression (21) regarding the target azimuth angle θ is obtained.

Further, in the above equation (21), the xyz three-dimensional coordinate value obtained by the magnetic vector obtaining unit (S2), the roll angle α _g , the pitch angle β _g obtained by the inclination angle obtaining unit (S12), the storage unit ( By substituting the xyz offset values stored in S4), the target azimuth angle θ can be obtained.

The electronic azimuth meter 2b to which the tilt sensor 6 is further added and the recording medium 10 have been described in addition to the configuration of the first embodiment. In addition to the conditions shown in the first embodiment, the xyz three-dimensional coordinate values of the present embodiment are also described. When acquiring data of four points with different values, an xyz offset value can be acquired with higher accuracy by adding a condition with different inclination angles.

  Further, similarly to the first embodiment, it is possible to determine whether or not the offset is being acquired by the geomagnetic amount determination means (S6), and the user of the electronic azimuth meter 2b can use it with peace of mind. For example, the same effects as in the first embodiment can be obtained.

In the first embodiment of the present invention, the four points of data acquired by the xyz offset acquisition means (S10) are described so as to select allowable values λ _α and λ _β and select values that exceed them. However, it is also possible to select a method in which the measured azimuth angle θ is separated. In this case, when the calculated value of the azimuth angle θ is fed back to the storage device 10 again and four different magnetic sensor outputs are selected, a function that selects azimuth angles θ as far as possible is selected. If it is further provided, a more accurate azimuth can be obtained.

The recording medium used in the electronic azimuth meter 2a, 2b of the present invention is not limited to this method, the arc tangent of the x _H output value S _h, divided by y _H corresponding to geomagnetism The target azimuth angle θ can also be obtained by calculation. According to this means, correction according to the inclination cannot be performed by the electronic azimuth meter, but the load of calculation of the azimuth is clearly reduced, and the target azimuth can be obtained more quickly.

  In addition, the xyz offset acquisition device 12 in each embodiment of the present invention has been described so as to acquire four xyz three-dimensional coordinate values from the storage device 10 when acquiring data. The number of acquisition points is not limited to four, and a plurality of data of four or more points may be acquired. Further, in the xyz offset acquisition means (S10), an example is shown in which an offset is acquired with four points of data. However, in order to select four points of data, four or more points of data are taken in, as described above. A method for performing such an allowable value calculation may be used.

  In addition, the electronic azimuth meters 2a and 2b shown in the first and second embodiments of the present invention may be electronic azimuth meters that are provided with a display device and a power source and operate alone. Further, in the recording medium used for the electronic azimuth meters 2a and 2b for incorporation into various electronic devices, the magnetic sensor 4, the tilt sensor 6, the geomagnetic quantity determination device 8, the storage device 10, the xyz offset acquisition device 12, and the azimuth calculation. The device 14 and the azimuth display device are not limited to be configured in one package. For example, various data storage, offset acquisition, and azimuth calculation functions are performed by CPUs and microcomputers on various devices. Also good.

It is a block block diagram which shows the structural example of the electronic bearing meter used as the basic composition of this invention. Example 1 It is a flowchart figure which shows the example of the recording medium used as the basic composition of this invention. Example 1 It is a block block diagram which shows the other structural example of the electronic bearing meter of this invention. (Example 2) It is a flowchart figure which shows the other example of the recording medium of this invention. (Example 2) It is the figure which showed the relationship between a magnetic vector, an offset vector, and a geomagnetic output vector when a magnetic sensor output is made into a coordinate axis in the conventional electronic azimuth meter. It is a figure explaining the offset acquisition method in the conventional electronic compass.

Explanation of symbols

2a, 2b Electronic azimuth meter 4 Magnetic sensor 6 Tilt sensor 8 Geomagnetic quantity determination device 10 Storage device 12 xyz offset acquisition device 14 Direction calculation device

Claims (11)

In electronic compass,
a magnetic sensor that obtains an xyz three-dimensional coordinate value that is an output value corresponding to a magnetic vector in the xyz-axis direction;
An xyz offset acquisition device for acquiring an xyz offset value resulting from an output other than geomagnetism;
An azimuth computing device for computing an azimuth using the xyz three-dimensional coordinate value and the xyz offset value;
A storage device for storing the xyz three-dimensional coordinate value, the xyz offset value, and an output corresponding to geomagnetism, respectively;
A current output value corresponding to geomagnetism, and an output value corresponding to geomagnetism acquired in the past, detecting whether or not there is a change in output corresponding to the geomagnetism, and outputting a geomagnetism determination device;
An electronic azimuth meter comprising:   The xyz offset acquisition device has a function of reacquiring the xyz offset value when an output change larger than a predetermined change amount is recognized as a result of output from the geomagnetism determination device. Item 2. An electronic compass according to item 1. a tilt sensor having a function of acquiring a pitch angle β _g formed by the x-axis and the horizontal plane and an output of a tilt angle corresponding to the roll angle α _g formed by the y-axis and the horizontal plane;
The electronic azimuth meter according to claim 1 or 2, wherein the azimuth computing device has a function of computing a azimuth based on the xyz three-dimensional coordinate value, the xyz offset value, and the tilt angle. magnetic vector acquisition means for acquiring an xyz three-dimensional coordinate value, which is an output value corresponding to a magnetic vector in the xyz axis direction, from a magnetic sensor;
Xyz offset acquisition means for acquiring an xyz offset value resulting from an output other than geomagnetism;
An azimuth calculating means for calculating an azimuth using the xyz three-dimensional coordinate value and the xyz offset value;
Storage means for storing the xyz three-dimensional coordinate value, the xyz offset value, and an output corresponding to the geomagnetism;
A current output value corresponding to geomagnetism and an output value corresponding to geomagnetism acquired in the past, detecting the presence or absence of a change in output corresponding to the geomagnetism, and outputting a geomagnetism determining means;
A recording medium for an electronic azimuth meter, comprising:   The xyz offset acquisition means receives the result of comparison by the geomagnetic quantity determination means, and when an output change larger than a predetermined change amount is recognized, the xyz offset value is recalculated to obtain the xyz offset value. The recording medium according to claim 4, which has a function of updating.   6. The xyz offset acquisition unit further has a function of acquiring four or more different xyz three-dimensional coordinate values from the plurality of xyz three-dimensional coordinate values acquired by the storage unit. The recording medium described in 1. The relationship between the xyz three-dimensional coordinate value (x _si , y _si , z _si ) serving as the reference value and the xyz three-dimensional coordinate value (x _sj , y _sj , z _sj ) to be compared with this reference value is set in advance. For the values δ _x , δ _y , δ _z ,

The recording medium according to claim 6, wherein: a tilt angle obtaining means for obtaining a pitch angle β _g formed by the x axis and the horizontal plane and an output of a tilt angle corresponding to the roll angle α _g formed by the y axis and the horizontal plane;
6. The recording medium according to claim 4, wherein the azimuth calculating means has a function of calculating an azimuth based on the xyz three-dimensional coordinate value, the xyz offset value, and the tilt angle. The xyz offset acquisition unit further has a function of acquiring four or more different xyz three-dimensional coordinate values from the plurality of xyz three-dimensional coordinate values acquired by the storage unit,
The storage means has a function of storing the tilt angle in correlation with the xyz three-dimensional coordinate value together with the xyz three-dimensional coordinate value, the xyz offset value, and an output value corresponding to the geomagnetism. The recording medium according to claim 8. The xyz offset acquisition means has a relationship between the inclination angle (α _gi , β _gi ) and the inclination angle (α _gj , β _gj ) with respect to preset allowable values λ _α , λ _β .

The recording medium according to claim 9, wherein four or more different xyz three-dimensional coordinate values are acquired so as to satisfy The relationship between the xyz three-dimensional coordinate value (x _si , y _si , z _si ) serving as the reference value and the xyz three-dimensional coordinate value (x _sj , y _sj , z _sj ) to be compared with the reference value is set in advance. For the tolerance values δ _x , δ _y , δ _z ,

The recording medium according to claim 10, wherein:

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