JP4551661B2 - Electronic compass, recording medium, and compass program - Google Patents

Description

  The present invention relates to an electronic azimuth meter that measures an azimuth using a magnetic sensor and a recording medium thereof. Specifically, the present invention relates to an electronic azimuth meter capable of correcting an offset when an offset other than geomagnetism occurs due to the influence of magnetization of a peripheral device 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 can be calculated from the direction determined as the reference 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.

  Although the above improvement in quality and accuracy indicates that the azimuth is measured more accurately, the azimuth may not be calculated accurately due to the influence of magnetization of peripheral devices of the magnetic sensor. When the magnetic sensor generates only an output corresponding to geomagnetism, the direction can be accurately calculated. However, if parts 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. Therefore, unless correction corresponding to the amount of magnetization is performed, an output corresponding to geomagnetism cannot be obtained, and a correct orientation cannot be obtained.

  As a conventional magnetization correction method for solving such a problem, there is known a method of obtaining an offset by rotating a device including a magnetic sensor once and calculating an average of the maximum value and the minimum value of the output. It has been. However, this method has the complication of having to rotate the device once, especially when you want to get an accurate bearing with an electronic compass mounted on a vehicle, etc. However, there was a problem that it took time and labor. Furthermore, the magnetization state is likely to change depending on the measurement environment including peripheral devices, and this magnetization amount changes over time, so even if it is performed once, the vehicle goes around once every time the magnetization state changes. There is a problem that a new correction must be performed.

A method and apparatus that can correct the azimuth error of the geomagnetic sensor without the trouble of turning the vehicle around the above-described problem has been disclosed (for example, see Patent Document 1). .
This is a method of obtaining and correcting an offset according to the magnetization amount of the peripheral device. Specifically, even after magnetization (after the magnetization state has changed), the magnetization state does not change thereafter. Using three points determined by three different sets of two-dimensional coordinate values sampled in between, a two-dimensional coordinate value (intersection of three circles) that is an offset at a predetermined distance from the three points is obtained, and this offset is obtained. To get the correct orientation.

  This method will be described in more detail with reference to the drawings. FIG. 7 shows the relationship between the outputs of the x and y axis magnetic sensors when the device including the electronic compass is rotated once in a horizontal state. In the drawing, the horizontal state means a state in which the pitch angle βg formed by the x axis and the horizontal plane is 0 degrees, and the roll angle αg formed by the y axis and the horizontal plane is 0 degrees, and one turn means an azimuth angle of 0 to 360 degrees. It shows that it rotates.

  It can be seen from FIG. 7 that the xy output graph under the horizontal state is circular. In addition, the radius of the circle at this time represents an output corresponding to the horizontal component of geomagnetism, and the center coordinates of the circle indicate the offset of the x magnetic sensor output and the y magnetic sensor output with respect to the origin. Here, when the xy two-dimensional coordinates of the three points on the output circle, for example, the xy output at the azimuth angles θ of 40 degrees, 90 degrees, and 310 degrees are known, the circle of θ = 40 deg and the angle of θ = 90 deg in FIG. The center coordinates (offset) can be obtained by using the intersection of each of the circle and the circle of θ = 310 deg. According to this method, even when the amount of magnetization of the peripheral device changes with time, an offset relating to magnetization can be acquired each time, so that the vehicle is often used particularly in a horizontal state. When installed, it can be a means for obtaining an accurate orientation.

JP-A-8-105745 (Page 6, FIG. 3)

When a user tries to obtain an azimuth while the electronic azimuth meter having the above-described function is tilted (in an inclined environment), that is, a user of an electronic azimuth meter for a portable device has various usage methods and possession. The magnetic sensor built in the electronic azimuth meter at that time may be used in an inclined state with respect to the horizontal plane.
However, in such an environment, there is a problem in that the above method cannot acquire an accurate offset, and thus the azimuth cannot be calculated accurately.

  The reason why an accurate offset cannot be obtained under the above-described tilt environment will be described in more detail with reference to the drawings. In FIG. 8, the roll angle αg formed by the y-axis and the horizontal plane is constant at 0 degree, and the pitch angle βg formed by the x-axis and the horizontal plane is 0 degrees (in the figure, indicated as “horizontal output circle”). The relationship between the output of the x- and y-axis magnetic sensors when the electronic azimuth meter including the magnetic sensor is rotated once at 20 degrees, 40 degrees, and 60 degrees is shown.

  From this figure, it can be seen that as the pitch angle βg increases, the output graph changes from a circular shape to an elliptical shape, and its center coordinates shift in order. In other words, the offset under the horizontal condition (true offset) is −30 mV on the x-axis and −110 mV on the y-axis from this figure, but as the tilt angle increases, deviation from the true offset occurs. That's it. Therefore, even if an attempt is made to obtain the center coordinates using the xy output coordinates of the three points on the ellipse in a tilted state, the output graph becomes an ellipse, and the center coordinates correspond to the inclination angle from the true offset. Because there are two phenomena of shifting, an accurate offset cannot be obtained. In this way, it is easy to understand that if an accurate offset cannot be obtained, an accurate offset according to the amount of magnetization of the peripheral device cannot be obtained in an inclined environment, and an accurate orientation cannot be obtained. I can do it.

Since there are many cases where the mobile device is used with the mobile device tilted to some extent in actual mobile device usage forms, it is practically impossible to obtain an offset each time with such a portable electronic device. . Therefore, in order to obtain an accurate azimuth, it is necessary to perform the troublesome calibration operation for obtaining the offset under the horizontal state again after returning from the inclined environment to the horizontal.

  Therefore, an object of the present invention is to obtain an offset even in any inclined environment, and even when the offset changes due to a change in the magnetized state, the user is not aware of it without performing a calibration that makes one round each time. It is an object of the present invention to provide an electronic azimuth meter and a recording medium that can automatically acquire an offset and obtain a true orientation.

  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 of the present invention includes a magnetic sensor arranged on the xyz axis having a function of acquiring an output corresponding to a magnetic vector in the xyz axis direction, a pitch angle βg formed between the x axis and the horizontal plane, a y axis and the horizontal plane. A tilt sensor having a function of acquiring an output of each tilt angle corresponding to the roll angle αg, and a horizontal magnetic vector arithmetic device having a horizontal conversion processing function for converting a magnetic vector into a horizontal xyz three-dimensional coordinate value using each tilt angle A tilt offset calculation device having a function of acquiring a tilt offset that is an offset corresponding to each tilt angle, and an azimuth calculation device that calculates an azimuth using the xyz three-dimensional coordinate value and the tilt offset. It is characterized in that the true orientation can be obtained by acquiring the offset of the orientation sensor generated by the influence of magnetism or the like.

  The electronic azimuth meter of the present invention further includes a tilt offset storage device having a function of storing a tilt offset corresponding to each tilt angle.

  Furthermore, the electronic compass of the present invention has three sets of data having the same tilt angle and different xyz three-dimensional coordinate values as the data storage device having a function of storing xyz three-dimensional coordinate values corresponding to each tilt angle. And a data acquisition device having a function of acquiring data from the data storage device.

  Furthermore, the electronic azimuth meter of the present invention further includes a vector quantity calculation device having a function of calculating a horizontal magnetic vector quantity using the xyz three-dimensional coordinate value and the tilt offset stored in the tilt offset storage device. Features.

  Furthermore, the electronic azimuth meter of the present invention further includes an azimuth display device having a function of displaying the azimuth obtained by the azimuth calculation device.

  The recording medium used for the electronic compass of the present invention includes a magnetic vector acquisition means for acquiring an output value corresponding to a magnetic vector in the xyz-axis direction from a magnetic sensor, a pitch angle βg formed by the x-axis and the horizontal plane, a y-axis and a horizontal plane. An inclination angle acquisition means for acquiring the roll angle αg formed from the inclination sensor, a horizontal conversion means for converting a magnetic vector into a horizontal xyz three-dimensional coordinate value using the inclination angle, and at least two sets of xyz three-dimensional coordinates corresponding to the inclination angle An azimuth generated by the influence of magnetization of a peripheral device, etc., comprising an inclination offset acquisition means for calculating and obtaining an inclination offset using a value, and an azimuth calculation means for calculating an azimuth angle using an xyz three-dimensional coordinate value and the inclination offset A program for acquiring a sensor offset and causing it to function so as to obtain a true orientation is recorded.

The recording medium used in the electronic azimuth meter of the present invention further has a function of storing the tilt offset calculated and acquired by the tilt offset acquisition means in the tilt offset storage device in correspondence with the tilt angle.

  Still further, the recording medium used in the electronic azimuth meter of the present invention has the maximum and minimum xyz three-dimensional coordinate values when the tilt offset acquisition means rotates the device once around the azimuth while the tilt angle is constant. It is a means for acquiring data calculated by averaging two points of values.

  Still further, the recording medium used for the electronic compass of the present invention includes three different sets of data storage means for sequentially storing the tilt angle and xyz three-dimensional coordinate values, and xyz three-dimensional coordinate values obtained by the data storage means. data acquisition means for acquiring xyz three-dimensional coordinate values, and the inclination offset acquisition means is means for calculating an inclination offset using three different sets of xyz three-dimensional coordinate values.

  Still further, in the recording medium used for the electronic azimuth meter of the present invention, the three sets of xyz three-dimensional coordinate values acquired by the data acquisition means are the same as the current inclination angle obtained by the inclination angle acquisition means, but are different. It is a coordinate value, and the inclination offset acquisition means is a means for acquiring an inclination offset corresponding to the current inclination angle.

  Furthermore, the recording medium used for the electronic compass of the present invention calculates the magnetic vector amount corresponding to the horizontal magnetic vector using the xyz three-dimensional coordinate value and the tilt offset, and the obtained magnetic vector amount and the past Magnetic vector amount calculation / comparison means for comparing the calculated magnetic vector quantity, inclination offset reacquisition means for recalculating the inclination offset to acquire the secondary inclination offset, and inclination offset storage means for storing the secondary inclination offset It is characterized by having.

  Furthermore, the recording medium used for the electronic azimuth meter of the present invention is further characterized by further comprising azimuth display means having a function of displaying the azimuth obtained by the azimuth calculation means.

  According to the present invention, it is possible to acquire a tilt offset corresponding to the tilt angle under an arbitrary tilt environment. Furthermore, even after the magnetized state changes in the tilt environment, the tilt offset can be automatically acquired without being noticed by the user by using it as it is.

  Specifically, a tilt offset that is an offset according to the tilt angle to be measured is calculated. Then, when the magnetic vector obtained from the magnetic sensor is horizontally converted in accordance with the inclination angle, the horizontally converted xy output coordinates use a circular shape centered on the inclination offset in accordance with the inclination angle. .

  Therefore, if the coordinate values of at least two points on the circle are known, the center coordinate can be calculated to obtain the tilt offset that is the center coordinate. Further, even when the magnetization state of the peripheral device changes, using the three sets of xyz three-dimensional coordinate values acquired while the magnetization state and the tilt angle do not change thereafter, a predetermined value is obtained from the three sets of xyz three-dimensional coordinate values. The slope offset can also be obtained by obtaining the coordinate value at a distance of, and in this case, the calibration can be automatically obtained without the user performing the calibration operation each time. It becomes possible.

  The basic configuration of the present invention includes a magnetic sensor, a tilt sensor, and a horizontal magnetic vector calculation device that is a calculation device having three different functions, a tilt offset calculation device, and an azimuth calculation device.

  In the steps until obtaining the azimuth by this configuration, first, the magnetic vector obtaining means obtains an output corresponding to the magnetic vector in the xyz axis direction from the magnetic sensor. Next, the tilt angle acquisition means acquires from the tilt sensor the output of each tilt angle corresponding to the pitch angle βg formed by the x-axis and the horizontal plane and the roll angle αg formed by the y-axis and the horizontal plane. Using the output of these sensors, the horizontal magnetic vector arithmetic unit performs horizontal conversion means for horizontally converting the magnetic vector corresponding to each inclination angle, and converts it into horizontal xyz three-dimensional coordinate values. Then, an inclination according to the inclination angle is calculated by the inclination offset calculation device to acquire the inclination offset. Finally, a means for calculating the azimuth using the obtained inclination offset and the xyz three-dimensional coordinate value is employed by the azimuth calculation device.

  The tilt offset will be described in more detail with reference to FIG. FIG. 9 is a diagram showing the concept of the tilt offset, where the horizontal xy output graph (shown as “horizontal output circle” in the figure), and the pitch angle βg formed by the x axis and the horizontal plane is 40 degrees. Output corresponding to the xyz three-dimensional coordinate value after further horizontal conversion processing (shown as “after horizontal conversion” in the figure).

  From this figure, as described above, the xy output value in the inclined state (the output value existing on the output graph of β = 40 deg in the figure) is on the ellipse and not on the circle. . It can also be seen that the center coordinates are also different from the horizontal center coordinates of the xy output circle. On the other hand, even in the xy output graph after horizontal conversion, the center coordinates thereof are different from the center coordinates of the horizontal xy output graph, but the xy output graph after horizontal conversion processing shows a circular shape, and the center coordinates thereof. It can be seen that indicates a tilt offset.

  This tilt offset is determined by the tilt angle and the true offset value. By performing horizontal conversion processing on this elliptical xy output, the xy output graph of xyz three-dimensional coordinates can be made into a substantially circular shape, and the azimuth is calculated by using the tilt offset that is the center coordinate. It becomes possible to do. Since the center coordinates are calculated when several points (for example, two or more points) on the circumference are known, an inclination offset is obtained by acquiring the xyz three-dimensional coordinate values after the horizontal conversion process. Is possible.

  As described above, the tilt offset is different from the true offset described in the background art, and indicates an offset corresponding to the tilt state. That is, in the conventional method, when the magnetization state fluctuates, a true offset cannot be obtained under an arbitrary tilt environment. Therefore, when using in an inclined environment, if the offset changes, it is necessary to perform calibration horizontally each time.

  On the other hand, in the present invention, the tilt offset and the xyz three-dimensional coordinate value are used. That is, even after the magnetization state of the peripheral device changes, it is possible to obtain several xyz three-dimensional coordinate values sampled in the magnetization state and calculate the tilt offset, which is troublesome for horizontal calibration and the like. Even if the procedure is not followed, it is possible to measure the correct orientation under any inclined environment.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a block configuration of an electronic azimuth meter according to the present invention, and FIG. 4 is a flowchart for explaining each step until obtaining an azimuth using the block configuration shown in FIG.

As shown in FIG. 1, the electronic compass 2 includes a magnetic sensor unit 4, a tilt sensor unit 6, a horizontal magnetic vector calculation device 8, a tilt offset calculation device 10, a tilt offset storage device 12, a direction calculation device 14, and a direction display device. 16 is composed. The magnetic sensor unit 4 is composed of x, y, and z axis magnetic sensors, and can obtain magnetic vectors by taking out outputs in the respective axial directions. The tilt sensor 6 is arranged on the x and y axes so that outputs corresponding to the pitch angle and roll angle can be obtained from the respective outputs.

  The horizontal magnetic vector calculation device 8 is a calculation device for converting a magnetic vector obtained from a magnetic sensor into a horizontal xyz three-dimensional coordinate value. As described above, an xy output existing on an ellipse in an inclined environment is output. It is a device for converting to exist on a circle. The tilt offset calculation device 10 is a device that calculates a tilt offset corresponding to each tilt angle from at least two sets of xyz three-dimensional coordinate values, and the tilt offset is stored in the tilt offset storage device 12 together with each tilt angle. . The azimuth calculation device 14 is a device that calculates the azimuth using the tilt offset and the xyz three-dimensional coordinate value, and the azimuth display device 16 is a device for displaying the azimuth.

Next, the recording medium used in the electronic azimuth meter of the present invention will be described more specifically with reference to FIG.
First, the magnetic vector acquisition means (S2) performed first is means for acquiring an output value corresponding to a magnetic vector in the xyz axis direction from the magnetic sensor. The magnetic vector obtained here is a combination of the output corresponding to the offset and the output corresponding to the geomagnetism. The inclination angle acquisition means (S4) to be performed next is means for acquiring the pitch angle βg formed by the x axis and the horizontal plane and the roll angle αg formed by the y axis and the horizontal plane from the inclination sensor. When an acceleration sensor is used as the tilt sensor, 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, storing a plurality of data and adding a process that averages these data results in a more stable output. Obtainable.

The horizontal conversion means (S6) is a means for converting the magnetic vector into a horizontal xyz three-dimensional coordinate value according to the pitch angle βg and roll angle αg obtained by the inclination angle acquisition means (S4). This means will be described specifically using mathematical expressions. The magnetic vector obtained by the magnetic sensor is (x _H , y _H , z _H ), and the xyz three-dimensional coordinate value obtained after the horizontal conversion is (x ′ _h , y ′ _h , z ′ _h ).
Assuming that the coordinate value of the vector obtained by rotating the magnetic vector by the inclination angle of the x-axis and the y-axis is an xyz three-dimensional coordinate value, the relational expression can be expressed by the following equation (1). In Equation 1, Xr represents a rotation matrix around the X axis, and Yr represents a rotation matrix around the Y axis.

By substituting the values obtained by the magnetic vector acquisition means (S2) and the tilt angle acquisition means (S4) into this equation 1, xyz three-dimensional coordinate values (x ′ _h , y ′ _h , z ′ _h ) are obtained. be able to.

In the inclination offset acquisition means (S8), the inclination offset is calculated using at least two sets of xyz three-dimensional coordinate values calculated by the horizontal conversion means (S6) and stored in the inclination offset storage device 12. Here, a description will be given of a case where a device including an electronic compass is rotated around an azimuth with the same tilt angle. In this case to retrieve the slope offset two sets of data to acquire the maximum value x _{'H_max} and the minimum value _x' h_min when the inclination angle was one circuit around the azimuth angle in the same state, with the average value some _{(x 'h_max + x' h_min} ) / 2 and tilting offset _x 'h_offs at the inclination angle. Similarly, _{y′h_offs} is acquired. Further, the calculated x ′ _{h_offs} and y ′ _{h_offs} are stored in the tilt offset storage device.

As described above, since x ′ _{h_offs} and y ′ _{h_offs} differ depending on the inclination angle, it is preferable to store data in a table format for each inclination angle. Further, since x ′ _{h_offs} and y ′ _{h_offs for} each inclination angle obtained once vary depending on the magnetization state of the peripheral device, it is preferable to use a RAM or the like so that it can be rewritten accordingly. Thus, the inclination offset acquisition means (S8) can acquire the inclination offset based on the inclination angle obtained by the inclination angle acquisition means (S4).

The azimuth calculation means (S10) uses the x ′ _h and y ′ _h calculated by the horizontal conversion means (S6) and the offsets x ′ _{h_offs} and y ′ _{h_offs} obtained by the inclination offset acquisition means (S8). Means for calculating are shown. Specifically, the azimuth angle θ is calculated by the following formula 2.

  Since θ that can be obtained above is a value in the range of −90 degrees to 90 degrees, in actual use, conditional branching can be performed based on the signs of xh and yh to calculate the azimuth angle θ. preferable. Finally, the obtained result is displayed by the direction display means (S12).

In the above method, the inclination offset is acquired by the inclination offset acquisition means (S8) and the azimuth is calculated. The result of concrete measurement will be described with reference to Table 1. Table 1, 'the maximum value of _h (x' x obtained while one circuit equipment including electronic azimuth meter _{H_max),} minimum value _(x 'h_min) and y' the maximum value of _h (y _{'H_max),} minimum It represents the value _(y 'h_min) and then calculates the _x' h_offs and y _{'h_offs.}

X _{H _offs} and y _{H _offs} and _{ZH _Offs} a true offset of the magnetic sensor, respectively -168mV, 291mV, was -120 mV. In this condition, the pitch angle βg formed by the x-axis and the horizontal plane becomes larger in -20 or et 40 °, as shown in section a ~ e section inclined offset x _{'H_offs} decreased. On the other hand, when the roll angle αg formed by the y-axis and the horizontal plane is increased, the inclination offset y ′ _{h_offs} is decreased as shown in the terms f to h. Further, when αg and βg change at the same time, both x ′ _{h_offs} and y ′ _{h_offs} change, and the slope offset x ′ _{h_offs} when αg = −20 and βg = 20 indicated by the term i is αg = 0 indicated by the term c, 'substantially equal to the value of _{h_offs,} y' x when the βg = 20 _{h_offs} is, .alpha.g = -20 indicated by h sections were almost the same as the value of y _{'H_offs} when the βg = 0 (h).

As described above, two sets of xyz three-dimensional coordinate values that are the maximum value (x ′ _{h — max} ) and the minimum value (x ′ _{h — min} ) of x ′ _h when the device is rotated once in a certain inclined environment are used. As a result, x ′ _{h_offs} which is a tilt offset of x can be obtained. Similarly, the same can be said for _{y'h_offs} .

Further, when both αg and βg are inclined, as described above, it is only necessary to acquire data in which either αg or βg overlaps 0 ° data. Specifically, for example .alpha.g = m, when the βg = n, 'αg = 0 as the value of _{H_offs,} x of .beta.g = n' x using _{H_offs,} as the value of _{y 'h_offs, αg = m,} βg = Y ′ _{h_offs} at 0 may be used.

  In order to obtain a more accurate slope offset, it is desirable to have a data table in which more data is recorded. However, if it is too much, it takes time to obtain the desired offset data. There should be a data table with a certain interval.

As described above, according to the electronic azimuth meter and the recording medium of the present invention, it is possible to acquire a tilt offset corresponding to an offset under an arbitrary tilt environment. Although the tilt offset changes according to the tilt angle, it is possible to cope with an arbitrary tilt environment by using the data table as in the present embodiment. The tilt offset can be calculated from the xyz three-dimensional coordinate value after the horizontal conversion, and the tilt offset can be obtained by making a round in the same manner as in the conventional method. This makes it possible to calculate the azimuth more accurately under an arbitrary tilt environment.

  Another embodiment of the present invention will be described. FIG. 2 is a block diagram showing a block configuration of an electronic azimuth meter according to the second embodiment of the present invention, and FIG. 5 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 in the present embodiment is basically the same as that in FIG. 1, but the data storage device 18 and the data acquisition device 20 are located between the horizontal magnetic vector calculation device 8 and the tilt offset calculation device 10. Only the points added are different from the previous embodiment. This data storage device 18 is a device having a function of storing the xyz three-dimensional coordinate values calculated by the horizontal magnetic vector calculation device in association with each inclination angle, and the data acquisition device 20 has the same inclination angle. In addition, the data storage device 18 has a function of acquiring three sets of data having different xyz three-dimensional coordinate values.

Embodiment 2 of the present invention will be described using the flowchart of FIG. Magnetic vector obtaining means shown in the flowchart (S2), the inclination angle obtaining means (S4), the horizontal transformation means (S6), a square-position calculating means (S10), the azimuth display means (S12) is the same as in the previous Example Because there is, explanation here is omitted.
The data storage means (S14) is means for storing the xyz three-dimensional coordinate values obtained by the horizontal conversion means (S6). A rewritable RAM is preferably used for the data storage device 18 so that data is sequentially written over time.

  The RAM which is the data storage device 18 is rewritten in order from the oldest when the data is full, so that the latest data is always left in the RAM. If the data capacity of the RAM is too small, the number of the latest data decreases, and data effective for offset calculation cannot be obtained. Therefore, it is desirable to have a certain capacity.

The data acquisition means (S16) is means for extracting three different sets of xyz three-dimensional coordinate values from the data stored in the data storage means (S14). The acquired data is calculated by the inclination offset acquisition means (S8). More specifically, the equation (3) below, to obtain the inclination O Fuse' preparative x _{'h_offs,} y' the _{H_offs.}

  The azimuth calculation means (S10) is the same as the previous embodiment, and finally the obtained result is displayed by the azimuth display means (S12).

  The azimuth angle obtained by this method will be described using experimental data. FIG. 10 shows the results of measuring the influence on the azimuth angle when the true offset of each xyz sensor is changed due to the influence of the magnetization of peripheral devices and the like in the prior art and the present invention. The horizontal axis of the graph shows the set azimuth angle, and the vertical axis shows the error angle that is the difference between the set azimuth angle and the calculated azimuth angle.

  From this graph, it can be seen that in the prior art, the azimuth error is increased due to the change in the magnetized state, but in the present invention, it can be seen that there is almost no error and the azimuth can be measured accurately. The change in the magnetization state of the peripheral device is that the true offset is (−150, 300, −150) for each axis of xyz, but is changed to (−125, 250, −165). It was found by subsequent measurements. Even in the prior art, there is almost no error if the calculation is performed using the true offset after the change of the magnetized state, but it is necessary to perform calibration each time. This result is an example, but it can be easily understood that the azimuth error increases as the change in the offset of each axis increases.

  Even if the magnetization state of the peripheral device is changed by the above procedure, an accurate inclination offset can be obtained by using three sets of xyz three-dimensional coordinate values acquired while the inclination state and the subsequent magnetization state are not changed. Can be acquired. Therefore, if the configuration and means of the present embodiment are employed, calibration can be automatically acquired without the user performing calibration operations each time.

In addition, it is preferable to select the three sets of data acquired by the data acquisition means (S16) that have different azimuth angles θ measured at that time. That is, it is possible to acquire a more accurate tilt offset by feeding back the calculated value of the azimuth angle θ to the data storage device 18 again. Specifically, the azimuth angle θ obtained from the data is stored together with the xyz three-dimensional coordinate value in the data storage device 18 and the inclination angles αg and βg. And by the data acquisition means (S16), when selecting a set of xyz3 dimensional coordinates, the inclined angle is the same as the current tilt angle, and select the one that far away as possible azimuth θ is the inclination A means for obtaining an accurate azimuth angle θ by acquiring an offset may be employed.

  Still another embodiment of the present invention will be described. FIG. 3 is a diagram showing a block configuration of an electronic compass in Embodiment 3 of the present invention, and FIG. 6 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 in this embodiment is basically the same as that in FIG. 2 except that a vector quantity calculation device 22 is added between the horizontal magnetic vector calculation device 8 and the data storage device 18. Only the difference. The vector calculation unit 22 then calculates the magnetic vector quantity corresponding to the magnetic vector is a device for comparing the data of the magnetic vector amount stored in the past.
In the second embodiment described above, it is necessary to always update data. However, according to this method, only necessary data is always stored, and calculation is performed based on the data to obtain a tilt offset. It becomes possible.

  The third embodiment of the present invention will be described in further detail using the flowchart of FIG. First, as in the previous embodiment, the magnetic vector acquisition means (S2), the inclination angle acquisition means (S4), and the horizontal conversion means (S6) acquire the inclination angle and xyz three-dimensional coordinate values. Then, the inclination offset acquisition unit (S8) reads the inclination offset value corresponding to the inclination angle from the data table stored in the inclination offset storage device 12.

Next, the magnetic vector quantity calculating means (S18), resulting xyz3 dimensional coordinate values of the x _'h and y' _h, and Starring magnetic vector quantity S'h with inclined offset _x 'h_offs and _y' h_offs Do the arithmetic. Specifically, the calculation is performed according to the following equation 4.

Then, a comparison of _h ^'S are stored in the past and ^_h' to the calculated S of the above, the calculated S _^'h compares determines whether within the range of preset tolerances. Within the scope computed S _^'h is the allowable value, performs an azimuth calculating means (S10) orientation display means (S12) using a gradient offset obtained previously.

Conversely, by comparing the S _^'h and the calculated ^S' _h stored in the past, when the computed S _^'h is out of the range of acceptable values, the inclination angle is that data Storage of xyz three-dimensional coordinate values is started by the data storage means (S14). When the data necessary for calculating the tilt offset is obtained, the data is extracted from the data acquisition unit (S16), and the tilt offset is re-calculated by the tilt offset re-acquisition unit (S20) to obtain the secondary tilt offset. When recalculation is performed, it is necessary to rewrite the slope offset value to a secondary slope offset value. This procedure is performed by the slope offset storage means (S22). According to FIG. 3 showing a block diagram, data is rewritten in the slope offset storage device 12.

  While the data necessary for the above-described tilt offset calculation is available, the azimuth calculation means (S10) and the azimuth display means (S12) are performed using the tilt offset values stored in the past. In some cases, information indicating that the calibration is in progress may be displayed in the direction display means (S12). In addition, the inclination angle may change from the current inclination angle during that time. In this case, it is desirable to stop the re-acquisition of the inclination offset and perform the process at the inclination angle again.

  With the above configuration, it is not always necessary to update data, it is possible to store only necessary data and obtain a tilt offset by calculation based on the data. And when the magnetization state of a peripheral device changes, inclination offset can be acquired using three sets of xyz three-dimensional coordinate values acquired while the magnetization state and inclination angle did not change after that.

  The electronic azimuth meter of the present invention in all the embodiments described above has been described on the assumption that all functions are supplemented by a single IC module. However, the present invention is not particularly limited thereto, and the display device An electronic azimuth meter having a power source and operating alone may be used. Further, even for incorporation into various electronic devices, the magnetic sensor 4, the tilt sensor 6, the arithmetic processing device 8, and the information input processing device 10 are not limited to one, but for example, the arithmetic processing device 8 or The functions of the information input processing device 10 may be performed by a CPU or a microcomputer on various devices.

  Moreover, in the electronic azimuth meter of the present invention, an example in which a calculation device and a storage device are separately provided for each function is shown, but it is not always necessary to provide a plurality of calculation devices and storage devices for each function, and the same calculation device, As long as it is a storage device, a single device may be configured to perform a plurality of functions.

It is the figure which showed the block configuration of the Example which is the basic composition of this invention. Example 1 It is the figure which showed the block configuration of the Example which added the data storage device and the data acquisition apparatus to the basic composition of this invention. (Example 2) It is the figure which showed the block configuration of the Example which added the data storage device, the data acquisition apparatus, and the vector quantity arithmetic unit to the basic composition of this invention. (Example 3) It is the figure which showed the flowchart of the Example which is the basic composition of this invention. Example 1 It is the figure which showed the flowchart of the Example of this invention. (Example 2) It is the figure which showed the flowchart of the Example of this invention. (Example 3) It is the figure which showed the relationship of the output of an x-axis and a y-axis magnetic sensor when an azimuth angle changes from 0 degree to 360 degree | times under a horizontal state. It is a figure showing the relation of the output of an x and y axis magnetic sensor when roll angle α is constant 0 degree and pitch angle βg is changed by 20 degrees from 0 degree to 60 degrees. It is the figure which showed the output corresponding to the xyz three-dimensional coordinate value after performing horizontal xy output, xy output whose pitch angle (beta) g is 40 degree | times, and horizontal conversion processing. It is the figure which showed the comparison result which computed the azimuth angle obtained by implementation of this invention in case of inclination | tilt angle (alpha) = 0 and (beta) = 40, and the azimuth angle by conventional implementation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Electronic azimuth meter 4 Magnetic sensor part 6 Inclination sensor part 8 Horizontal magnetic vector calculating apparatus 10 Inclination offset calculating apparatus 12 Inclination offset memory | storage apparatus 14 Direction calculating apparatus 16 Direction display apparatus 18 Data storage apparatus 20 Data acquisition apparatus 22 Vector quantity calculating apparatus

Claims (4)

a magnetic sensor disposed on the xyz axis for obtaining an output corresponding to a magnetic vector in the xyz axis direction;
an inclination sensor for obtaining an output of an inclination angle corresponding to a pitch angle βg formed by the x axis and the horizontal plane and a roll angle αg formed by the y axis and the horizontal plane;
A horizontal magnetic vector arithmetic device that converts a magnetic vector into a horizontal xyz three-dimensional coordinate value using the tilt angle ;
A data storage device for storing a plurality of inclination angles when the postures of the magnetic sensor and the inclination sensor are different, and the horizontal xyz three-dimensional coordinate values together with the inclination angles;
At least three sets of data selected from the plurality of inclination angles and having the same inclination angle as the current apparatus inclination angle and having different horizontal xyz three-dimensional coordinate values are acquired from the data storage device. A data acquisition device;
Using said at least three sets of data acquired by the data acquisition device, and the tilt offset calculating device for calculating a tilt offset,
And xyz3 dimensional coordinate values of the current horizontal, using the tilt offset, the electronic azimuth meter, characterized in that it comprises a bearing calculation unit for calculating an azimuth, a. A magnetic vector amount is calculated using the horizontal xyz three-dimensional coordinate value and the tilt offset stored in the tilt offset storage device, and the magnetic vector amount obtained here, and a magnetic vector amount calculated in the past, Further comprising a vector quantity computing device for comparing
When determining that the magnetic vector quantity is outside the range of the preset allowable value, the vector quantity calculation device causes the data storage device and the tilt offset calculation device to function to reacquire the tilt offset. And
When the magnetic vector quantity is determined to be within the range of the allowable value, by using as the tilt offset previously obtained, to claim 1, characterized in that computing the azimuth by the azimuth calculation unit The electronic compass as described. obtaining an output value corresponding to a magnetic vector in the xyz-axis direction from the magnetic sensor;
obtaining a pitch angle βg formed by the x-axis and the horizontal plane and a roll angle αg formed by the y-axis and the horizontal plane from the tilt sensor;
Using the tilt angle, the magnetic vector in the xyz axis direction is converted into a horizontal xyz three-dimensional coordinate value.
Converting , and
Storing a plurality of inclination angles when the postures of the magnetic sensor and the inclination sensor are different from each other and the horizontal xyz three-dimensional coordinate values together with the inclination angles;
Selecting and acquiring at least three sets of data that are selected from the plurality of inclination angles and that have the same inclination angle as that of the current device and have different horizontal xyz three-dimensional coordinate values; ,
Calculating a tilt offset using the at least three sets of data ;
Using the tilt offset and xyz3 dimensional coordinate values of the current horizontal, computer-readable recording medium storing a program for executing the steps of: recording a program for calculating the azimuth angle. obtaining an output value corresponding to a magnetic vector in the xyz-axis direction from the magnetic sensor;
obtaining a pitch angle βg formed by the x-axis and the horizontal plane and a roll angle αg formed by the y-axis and the horizontal plane from the tilt sensor;
Converting the magnetic vector in the xyz-axis direction into a horizontal xyz three-dimensional coordinate value using the tilt angle;
Storing a plurality of inclination angles when the postures of the magnetic sensor and the inclination sensor are different from each other and the horizontal xyz three-dimensional coordinate values together with the inclination angles;
Selecting and acquiring at least three sets of data that are selected from the plurality of inclination angles and that have the same inclination angle as that of the current device and have different horizontal xyz three-dimensional coordinate values; ,
Calculating a tilt offset using the at least three sets of data;
An azimuth calculation program for causing a computer to execute an azimuth calculation step using a current horizontal xyz three-dimensional coordinate value and the tilt offset.

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