JP5125534B2 - Direction detection device and direction detection program - Google Patents

Description

  The present invention relates to an azimuth detection apparatus and an azimuth detection program for detecting an azimuth angle indicated by an apparatus main body on which the electronic compass is mounted using an electronic compass.

  Conventionally, when a disturbance due to an external magnetic field occurs, the geomagnetic sensor mounted on the moving body cannot accurately determine the azimuth, and when the disturbance is very large, a residual magnetic field is generated on the moving body. This phenomenon is called magnetization, and when magnetization occurs, it becomes impossible to accurately determine the direction of geomagnetism due to the residual magnetic field, resulting in a decrease in the reliability of the navigation system. For this reason, the technique which simplified the magnetization determination is disclosed (for example, refer the following patent document 1).

JP-A-5-79842

  However, since the above-described prior art is a technique for preventing misjudgment of the orientation due to the residual magnetic field due to magnetization, when the geomagnetic sensor reacts with an external magnetic source other than the residual magnetic field, naturally the geomagnetism is caused by this magnetic source. Cannot be captured normally. Therefore, if there is a magnetic source nearby, there is a problem that the orientation of the moving body cannot be obtained accurately.

  In addition, the azimuth of the moving object can be obtained using the angular velocity obtained from the gyro sensor. However, when the azimuth of the moving object is obtained by the gyro sensor, the integral value of the obtained angular velocity is accumulated, and errors are accumulated steadily. As a result, there is a problem that the orientation of the moving body cannot be obtained accurately.

  An object of the present invention is to provide an azimuth detection apparatus and an azimuth detection program that can easily and accurately detect the traveling azimuth of a moving body in order to solve the above-described problems caused by the prior art.

  In order to solve the above-described problems and achieve the object, the azimuth detecting device and the azimuth detecting program include a first electronic compass that outputs a first detection signal based on geomagnetism, and a second electronic compass that outputs the first detection signal based on the geomagnetism. A second electronic compass that outputs a detection signal; and a first azimuth angle indicated by the device main body based on the first detection signal, and a second detection signal. A second azimuth angle pointed to by the apparatus main body is obtained based on the calculation, a azimuth difference between the first and second azimuth angles is calculated, and whether the calculated azimuth difference is equal to or greater than a predetermined threshold value is determined. If it is determined that it is greater than or equal to the threshold value, it is a requirement that an output indicating that it is affected by magnetism other than geomagnetism is performed.

  According to this azimuth detection device and azimuth detection program, when the influence of an external magnetic source (excluding geomagnetism) other than the moving body including the device main body and the device main body is weak, the geomagnetism can be normally captured. The azimuth difference between the first azimuth angle and the second azimuth angle is less than the threshold value. On the other hand, when the influence of the magnetic source is strong, since the geomagnetism cannot be detected normally, the azimuth difference is equal to or greater than the threshold value. Therefore, it is possible to easily detect a deviation of the electronic compass due to the influence of the magnetic source.

  In addition, in the azimuth detecting device and the azimuth detecting program, when it is determined that the predetermined threshold value is not exceeded, one of the first and second azimuth angles acquired this time is output. Also good.

  According to this azimuth detection apparatus and azimuth detection program, an accurate azimuth angle can be output by an electronic compass.

  In the azimuth detecting device and the azimuth detecting program, a gyro sensor provided in the device main body for detecting an angular velocity in a horizontal direction of the device main body is provided, and a direction of a predetermined horizontal component is determined based on a detection result from the gyro sensor. The angle of the horizontal component of the apparatus main body with respect to the first and second azimuth angles, and the first and second azimuth angles of the apparatus main body acquired at the previous acquisition of the first and second azimuth angles. Calculate the angle difference with the angle of the device main body acquired at the time of the current acquisition, and if it is determined that the current azimuth difference is greater than or equal to the predetermined threshold, the azimuth angle of the device main body output last time And the current azimuth angle of the apparatus main body may be calculated based on the calculated angle difference and the calculated current azimuth angle of the apparatus main body may be output.

  According to this azimuth detection device and azimuth detection program, only when the influence of the magnetic source is strong, the current azimuth angle of the device main body is determined based on the azimuth angle output last time and the difference between the previous time and the current angle by the gyro sensor. Is calculated. Here, the azimuth angle output last time is a normal azimuth angle obtained from the electronic compass when the influence of the magnetic source is weak. Further, since the angle difference obtained from the gyro sensor is obtained from the previous angle and the current angle, the accumulation of errors by the gyro sensor is kept to a minimum. Therefore, a highly accurate azimuth can be obtained even at a point where the influence of the magnetic source is strong.

  According to this azimuth detection device and azimuth detection program, there is an effect that the traveling azimuth of the moving body can be detected easily and with high accuracy.

  Exemplary embodiments of the azimuth detection device and the azimuth detection program will be described below in detail with reference to the accompanying drawings. In the present embodiment, two electronic compass are mounted on the apparatus main body. When the influence of an external magnetic source (excluding geomagnetism) other than the apparatus main body and the moving body including the apparatus main body is weak, the geomagnetism can be normally captured by both electronic compasses, and therefore the first azimuth and second The azimuth difference with the azimuth is less than the threshold value. On the other hand, when the influence of the magnetic source is strong, since the geomagnetism cannot be detected normally, the azimuth difference is equal to or greater than the threshold value. Therefore, it is possible to easily detect a deviation of the electronic compass due to the influence of the magnetic source. Further, when such a deviation occurs, the current azimuth can be predicted by using the angle difference obtained from the gyro sensor.

(Hardware configuration of orientation detection device)
FIG. 1 is an explanatory diagram showing a hardware configuration of the azimuth detecting device according to the present embodiment. In FIG. 1, an azimuth detecting device 100 includes a CPU 101, a memory 102, an input device 103, a display 104, a communication I / F 105, a first electronic compass 106a, a second electronic compass 106b, a gyro sensor 107, an acceleration sensor 108, and a GPS 109. (Global Positioning System) is connected by a bus 110.

  The CPU 101 governs overall control of the direction detection device 100. The memory 102 includes a ROM, RAM, HD, optical disk, flash memory, and the like. The memory 102 is used as a work area for the CPU 101 and a storage area for various data. In addition, various programs are stored in the memory 102 and loaded according to instructions from the CPU 101.

  The input device 103 includes a keyboard, numeric keys, direction keys, a touch panel, a mouse, and the like. The display 104 displays character data, map data, current position, and direction. The communication I / F 105 controls data communication with the outside. For example, map data is received. The GPS 109 detects the current position.

  The first electronic compass 106a and the second electronic compass 106b detect geomagnetism, and output detection signals related to the azimuth angle indicated by the apparatus main body based on the geomagnetism. The first electronic compass 106a and the second electronic compass 106b are arranged at a predetermined interval in the apparatus main body. The first electronic compass 106a and the second electronic compass 106b include X-axis geomagnetic sensors 161a and 161b, Y-axis geomagnetic sensors 162a and 162b, and control ICs 163a and 163b, respectively.

  Here, the X axis and the Y axis are two axes constituting a horizontal plane. In the first electronic compass 106a, the X-axis geomagnetic sensor 161a and the Y-axis geomagnetic sensor 162a are arranged so as to be orthogonal to each other. In the second electronic compass 106b, the X-axis geomagnetic sensor 161b and the Y-axis geomagnetic sensor 162b are arranged so as to be orthogonal to each other.

  The first electronic compass 106a and the second electronic compass 106b are preferably installed in the same posture. That is, both X-axis geomagnetic sensors 161a and 161b are provided in parallel, and both Y-axis geomagnetic sensors 162a and 162b are also provided in parallel. In this way, when there is no magnetic source, the geomagnetism can be captured normally, so the value obtained from the first electronic compass 106a and the value obtained from the second electronic compass 106b are the same.

  Further, even if they are not in the same posture, (1) they are mounted in the same posture at the time of manufacture, (2) the orientation detection device 100 is rotated 360 degrees, and (3) the first electronic compass 106a and the second electronic The value of the compass 106b is acquired. (4) The obtained values are individually corrected. Specifically, an offset value is obtained so that the largest difference between the maximum value and the minimum value is divided by 360, and half of the difference is 180. (5) Finally, the values corrected in (4) are compared, and an offset value is determined so as to be the same. In this way, when there is no magnetic source, the geomagnetism can be captured normally, so the value obtained from the first electronic compass 106a and the value obtained from the second electronic compass 106b are the same.

  In the present embodiment, the first electronic compass 106a and the second electronic compass 106b are two axes of the X axis and the Y axis, but may be three axes including the Z axis which is the vertical direction. As the geomagnetic sensor, an MI element, a Hall element, a fluxgate sensor, a GMR element, or the like can be used, but an MI element is preferably used in terms of element sensitivity and reaction speed. The accuracy of the azimuth angle obtained from the MI element is determined by the bit rate of the AD converter in the control IC. Currently, since a 16-bit AD converter is used, the minimum resolution is 360 degrees / 256 degrees, but if it is 32 bits, it is 360 degrees / 65536.

  The gyro sensor 107 is provided in the apparatus main body and detects an angular velocity in the horizontal direction of the apparatus main body. As the gyro sensor 107, a ring laser gyro or a vibration gyro can be employed. However, the vibration gyro is preferable in terms of low cost, small size, light weight, and low power consumption. In the present embodiment, since the first electronic compass 106a and the second electronic compass 106b have two axes, the gyro sensor 107 also has two axes, the X axis and the Y axis.

  When the first electronic compass 106a and the second electronic compass 106b have three axes, the gyro sensor 107 also has three axes. The measurement timing of the angular velocity by the gyro sensor 107 is preferably set so as to be synchronized with the output timing of the detection signal from the first electronic compass 106a and the second electronic compass 106b.

  In any case, since the Z-axis is an axis for correcting when the XY plane is not horizontal, the first electronic compass 106a, the second electronic compass 106b, and the gyro sensor 107 are at least X-axis. What is necessary is just to be comprised by 2 axes | shafts of an axis | shaft and a Y-axis. The acceleration sensor 108 detects the acceleration of the apparatus main body. The movement distance of the apparatus main body can be calculated by integrating the detected acceleration twice. The GPS 109 detects the current position of the apparatus main body.

  FIG. 2 is a plan view showing a passage inside the building. In the building 200, reference numeral 201 denotes a passage, reference numeral 202 denotes a magnetic source, and a dot-and-dash area indicated by reference numeral 203 is an area affected by the magnetic source.

  The user carrying the azimuth detecting device 100 moves from the point P0, which is the entrance, in the order of P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, and P12. Within the building 200, the current position by the GPS 109 is not detected. In the section from the points P0 to P8, geomagnetism can be normally captured by the first electronic compass 106a and the second electronic compass 106b. On the other hand, in the section between the points P9 to P11 in the region 203, the first electronic compass 106a and the second electronic compass 106b are not normally able to capture the geomagnetism by being dragged by the magnetic source 202, and the azimuth angle obtained The orientation difference of becomes larger.

  Therefore, in the section between the points P9 to P11, the values of the first electronic compass 106a and the second electronic compass 106b at the position immediately before the geomagnetism can be normally captured (here, the point P8) are temporarily Then, the azimuth angle of the apparatus main body at the points P9 to P11 is detected by correcting with the angle of the apparatus main body at the points P8 to P11 obtained from the gyro sensor 107. When it moves to the point P12, it will be outside the region 203, so that the geomagnetism can be normally captured by the first electronic compass 106a and the second electronic compass 106b.

  FIG. 3 is an explanatory diagram (part 1) showing the stored contents of a table indicating values obtained for each point shown in FIG. In the example shown in FIG. 3, the point P8 in FIG. 2 is the current position. The value obtained from the first electronic compass 106a and the second electronic compass 106b is an azimuth angle with reference to the north (magnetic north), but the angle obtained from the gyro sensor 107 is the value obtained when the GPS 109 is not received. The direction indicated by the azimuth detecting device 100 is a reference. In the example of FIG. 2, the GPS 109 is no longer received at the point P0, so the west (W) is the reference. That is, it is 0 degrees when facing west.

In FIG. 3, i (i = 0, 1, 2,...) Is a subscript representing a point. The azimuth angle ca _i is an azimuth angle indicated by the azimuth detection apparatus 100 obtained from the detection signal of the first electronic compass 106a. The flag f _i is a flag for specifying the azimuth angle ca _i to be referred to when the geomagnetism cannot be normally captured. Reference is made when the value of the flag f _i is “0”, but not “1”. The setting of the flag f _i will be described later. The value of the flag _{f 8} azimuth ca ₈ at a point P8 in the example of FIG. 2 is changed from "0" to "1" (FIG. 3 remains "0").

The azimuth angle cb _i is an azimuth angle indicated by the azimuth detection apparatus 100 obtained from the detection signal of the second electronic compass 106b. The measurement angle θi is an angle of the horizontal component of the azimuth detecting device 100 obtained from the angular velocity output from the gyro sensor 107. Angular difference d [theta] _i is a value obtained by subtracting the previous measured angle theta _i-1 from the current measured angle theta _i. In FIG. 3, all the signs are “−” because the geomagnetism can be normally captured and the azimuth angle ca _i can be used as it is, so that it is not necessary to calculate.

The accumulated angle Θ _i is an integrated value of the measurement angles so far. Actually, it is not necessary to calculate the cumulative angle Θ _i , but here, it is shown in order to express how much error propagation of the gyro sensor 107 exists. The output azimuth angle c _i is the azimuth angle that is finally output. Here, when the geomagnetism is normally captured, the azimuth angle ca _i is directly used as the output azimuth angle c _i . In the example of FIG. 3, the azimuth angle ca _i and the azimuth angle cb _i have the same value up to the points P0 to P4. However, since the points P5 to P8 gradually approach the magnetic source 202, The angle ca _i and the azimuth angle cb _i are different.

FIG. 4 is an explanatory diagram (part 2) showing the stored contents of a table indicating values obtained for each point shown in FIG. In the example shown in FIG. 4, the point P10 in FIG. 2 is the current position. Since the points P9 and P10 are in the region 203, they are affected by the magnetic source 202. That is, the azimuth difference Δc _i between the azimuth angle ca _i and the azimuth angle cb _i is equal to or greater than the predetermined threshold value C.

This threshold value C is set according to the resolution and the installation interval of the first electronic compass 106a and the second electronic compass 106b. Here, C = 3. The bearing difference Δc ₉ at the point P9 is Δc ₉ = 3, which is equal to or greater than the threshold value C. By making a transition from a state below the threshold C to a state above the threshold C, the value of the previous flag f _i−1 is changed from “0” to “1”. Here, because of the state transition above the threshold value C at the point P9, the value of the flag f ₈ at the point P8 to "1" to "0".

Since the point P9 is equal to or greater than the threshold value C, the angle difference dθ _i is calculated. Specifically, the angle difference dθ ₉ (= 0) is calculated by subtracting the measurement angle θ ₈ (= 0) at the point P8 from the measurement angle θ ₉ (= 0) at the point P9. Therefore, the output azimuth angle _{c 9} at the point P9, the value of the flag _{f i} is the sum of the value and the angle difference d [theta] ₉ of the azimuth angle ca ₈ is "1".

Similarly, since the point P10 is equal to or greater than the threshold value C, the angle difference dθ _i is calculated. Specifically, the angle difference dθ ₁₀ (= −89) is calculated by subtracting the measurement angle θ ₉ (= 0) at the point P9 from the measurement angle θ ₁₀ (= −89) at the point P10. Therefore, the output azimuth angle _{c 10} at the point P10, the value of the flag _{f i} is the sum of the values and angular difference d [theta] ₉ and angular difference d [theta] ₁₀ of the azimuth angle ca ₈ is "1".

Here, paying attention to the accumulated angle Θi, when the azimuth is detected only from the point P0 by the gyro sensor 107, the reference angle at the point P0 is 0, but since it is facing west, it is 270 degrees when expressed in the azimuth angle. is there. When the cumulative angle Θ ₉ = 2 is added to this 270 degrees, it becomes 272 degrees. Therefore, it is possible to detect the azimuth with higher accuracy than detecting the azimuth from the point P0 only by the gyro sensor 107.

FIG. 5 is an explanatory diagram (part 3) showing the stored contents of a table showing values obtained for each point shown in FIG. In the example shown in FIG. 5, the point P12 in FIG. 2 is the current position. Since the point P12 is outside the region 203, it is not affected by the magnetic source 202, and the azimuth difference Δc _i between the azimuth angle ca _i and the azimuth angle cb _i is less than the threshold value C. That is, the azimuth difference Δc ₁₂ = 0 between the azimuth angle ca ₁₂ and the azimuth angle cb ₁₂ is less than the threshold value C. Therefore, the angle difference dθ ₁₂ is not calculated, and the azimuth angle ca ₁₂ becomes the output azimuth angle c ₁₂ as it is.

As described above, the state of the flag f _i whose value is “1” is changed from “1” to “0” by making the transition from the state above the threshold C to the state below the threshold C. Here, because of the state transition below the threshold C at point P12, the value of the flag f ₈ at the point P8 value is "1" to "1" to "0".

In this way, by resetting the flag when the transition is less than the threshold value C, the azimuth angle ca _{i serving} as a reference destination can be set to the azimuth immediately before the geomagnetism can be normally captured. Thereby, the angle difference obtained from the gyro sensor 107 can be kept to the minimum necessary, and the influence of error propagation by the gyro sensor 107 can be suppressed.

(Functional configuration of orientation detection apparatus 100)
FIG. 6 is a block diagram showing a functional configuration of the azimuth detecting device 100. 6, the azimuth detection apparatus 100 includes an azimuth angle acquisition unit 601, an azimuth difference calculation unit 602, a determination unit 603, a detection unit 604, an angle acquisition unit 605, an angle difference calculation unit 606, and an azimuth angle calculation. A part 607, a current position specifying part 608, and an output part 609.

The azimuth angle acquisition unit 601 has a function of acquiring the azimuth angle ca _i indicated by the apparatus main body based on the detection signal output from the first electronic compass 106a and the detection signal output from the second electronic compass 106b. based on, and a function of acquiring azimuth cb _i indicated by the apparatus main body. From the first electronic compass 106a, the electrical signal from the X-axis geomagnetic sensor and the electrical signal from the Y-axis geomagnetic sensor are signal-processed and output as detection signals.

The azimuth angle ca _i can be calculated by taking arctan of the X-axis and Y-axis detection signal values. The second electronic compass 106b also calculates the azimuth angle cb _i by the same method. The azimuth acquisition unit 601 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

The azimuth difference calculation unit 602 has a function of calculating an azimuth difference Δc _i between the azimuth angle ca _i and the azimuth angle cb _i . Specifically, Δc _i = ca _i −cb _i is calculated. The azimuth difference calculation unit 602 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

The determination unit 603 has a function of determining whether or not the azimuth difference Δc _i is greater than or equal to a predetermined threshold value C. When the threshold value C is equal to or higher than the threshold value C, the first electronic compass 106a and the second electronic compass 106b are not normally capturing geomagnetism by the magnetic source 202. On the other hand, when it is less than the threshold value C, the first electronic compass 106 a and the second electronic compass 106 b are normally capturing the geomagnetism by the magnetic source 202.

  As described above, the threshold value C is set according to the resolution and the installation interval of the first electronic compass 106a and the second electronic compass 106b. The determination unit 603 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

  The detection unit 604 has a function of detecting the current position of the apparatus main body. A coordinate value indicating the detected current position is sent to the current position specifying unit 608. The detecting unit 604 realizes its function by the GPS 109 shown in FIG.

The angle acquisition unit 605 has a function of acquiring the angle θ _i of the horizontal component of the apparatus main body based on the direction of the predetermined horizontal component based on the detection result from the gyro sensor 107. Specifically, for example, when the current position is no longer detected by the detection unit 604, the gyro sensor 107 starts measurement and integrates the obtained angular velocity to obtain the horizontal component immediately before the current position is not detected. The angle θ _i of the horizontal component of the apparatus main body with respect to the direction is acquired.

  In the example of FIG. 2, the west (W) direction at the point P0 is the reference direction, and the angle in that direction is 0 degrees. The angle acquisition unit 605 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

The angle difference calculation unit 606 includes the angle θ _i−1 of the apparatus main body acquired when the azimuth angles ca _i−1 and cb _i−1 are acquired, and the apparatus main body acquired when the azimuth angles ca _i and cb _i are acquired. It has a function of calculating an angle difference dθ _i from the angle θ _i . Specifically, dθ _i = θ _i −θ _i−1 is calculated. The angle difference calculation unit 606 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

When the determination unit 603 determines that the current azimuth difference Δc _i is greater than or equal to a predetermined threshold C, the azimuth calculation unit 607 calculates the angle difference from the previously output azimuth c _{i−1 of} the apparatus body. Based on the angle difference dθ _i calculated by the unit 606, the apparatus has a function of calculating the current azimuth angle c _i of the apparatus main body. Specifically, c _i = c _i−1 + dθ _i is calculated. The angle difference calculation unit 606 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

The current position specifying unit 608 has a function of specifying the current position of the apparatus main body. Specifically, when the current position is detected by the detection unit 604, the current position is specified as it is. If not detected, the current position is specified by the value of the twice integral of acceleration obtained from the acceleration sensor 108 and the angle θ _i at each point obtained from the angle acquisition unit 605.

Specifically, taking FIG. 2 as an example, when the point P0 is used as a reference, the movement distance can be obtained by the value of the double integration of the acceleration obtained from the acceleration sensor 108. Therefore, the reference direction (westward) at the point P0 The next point P1 can be specified by the angle θ _i . The same applies to the other points P2 to P12. The current position specifying unit 608 realizes its function by causing the CPU 101 to execute a program stored in the memory 102 shown in FIG.

The output unit 609 has a function of outputting the output azimuth angle _{c i.} Specifically, when the determination unit 603 determines that the value is less than the threshold value C, the current azimuth angle ca _i is output as the output azimuth angle c _i . On the other hand, when it is determined that the value is equal to or greater than the threshold value C, the output azimuth angle c _i calculated by the azimuth calculation unit 607 is output. Further, when outputting, the current position specified by the current position specifying unit 608 may be output together.

Alternatively, map data may be acquired, the map data and the current position may be displayed on the display 104, and an arrow indicating the output azimuth angle c _i may be displayed on an icon indicating the current position. Further, these pieces of information may be transmitted to an external device through the communication I / F 105, or may be output as sound or printed. The output unit 609 realizes its function by the display 104, the communication I / F 105, and the like.

(Azimuth angle detection processing procedure)
7 to 9 are flowcharts showing the azimuth angle detection processing procedure. FIG. 7 is a flowchart in a state where the current position is detected by the GPS 109. Therefore, the azimuth detection process is performed by the first electronic compass 106a and the second electronic compass 106b.

First, it is determined whether or not the current position is detected by the detection unit 604 (GPS 109) (step S701). If it is detected (step S701: Yes), obtains the azimuth cb _i by azimuth ca _i and second electronic compass 106b of the first electronic compass 106a azimuthally acquisition unit 601 (step S702). Then, the acquired azimuth angles ca _i and cb _i are stored in the memory 102 (step S703). Thereafter, the output unit 609 executes azimuth angle output processing (step S704), and the process returns to step S701. On the other hand, if it is not detected in step S701 (step S701: No), the process proceeds to step S801 in FIG.

  The flowchart of FIG. 8 is a flowchart when the gyro sensor 107 is operating. The gyro sensor 107 operates from when the current position is no longer detected by the detection unit 604 (GPS 109) until it is next detected.

First, when the current position is no longer detected (step S701: No), measurement by the gyro sensor 107 is started (step S801). Next, the azimuth angle acquisition unit 601 acquires the azimuth angle ca _i by the first electronic compass 106a and the azimuth angle cb _i by the second electronic compass 106b, and the angle acquisition unit 605 acquires the angle θ _i (step). S802). Then, the acquired azimuth angles ca _i and cb _i and the angle θ _i are stored in the memory 102 (step S803).

Thereafter, the azimuth difference calculation unit 602 calculates the azimuth difference Δc _i (step S804). Then, the determination unit 603 determines whether or not the azimuth difference Δc _i is greater than or equal to the threshold value C (step S805). If the azimuth difference Δc _i is not equal to or greater than the threshold value C (step S805: No), the current position is specified by the current position specifying unit 608 (step S806). Then, the azimuth output process is performed by the output unit 609 (step S807), and the flag whose value is “1” is reset (step S808).

Thereafter, it is determined whether or not the current position is detected by the detection unit 604 (GPS 109) (step S809), and if not detected (step S809: No), the process returns to step S802. On the other hand, when detected (step S809: Yes), the measurement of the gyro sensor 107 is stopped (step S810), and the process returns to step S702. In this way, power saving can be achieved by restricting the operation of the gyro sensor 107. Further, in step S805, the case where the orientation difference .DELTA.c _i is determined to be equal to or greater than the threshold value C (step S805: Yes), the process proceeds to step S901.

The flowchart in FIG. 9 is a flowchart for obtaining the output azimuth angle c _i using the angle θ _i obtained from the gyro sensor 107. In FIG. 8, when it is determined that the azimuth difference Δc _i is equal to or greater than the threshold value C (step S805: Yes), the angle difference dθ _i is calculated (step S901). Next, it is determined whether or not there is a flag having a value of “1” in the table (step S902).

When the flag having the value “1” exists in the table (step S902: Yes), the process proceeds to step S904. On the other hand, if not (step S902: No), the value of the flag f _i-1 of the previous azimuth angle ca _i-1 of the first electronic compass 106a is set from "0" to "1" (step S903). The process proceeds to step S904. In step S904, the current output azimuth angle c _i is calculated by adding the angle difference dθ _i calculated in step S901 to the previous output azimuth angle c _i−1 (step S904). The current position is specified by the current position specifying unit 608 (step S905), and the azimuth output process is performed by the output unit 609 (step S906). Thereafter, the process proceeds to step S809.

  In the above-described flowchart, when the current position is no longer detected by the GPS 109, the processing shown in FIGS. 8 and 9 is executed. However, regardless of the detection by the GPS 109, the gyro sensor 107 is measured. Alternatively, the processing of FIGS. 8 and 9 may be executed.

According to the present embodiment, when the influence of an external magnetic source 202 (excluding geomagnetism) other than the apparatus main body and the mobile body including the apparatus main body is weak, the geomagnetism can be normally captured, and thus the azimuth angle ca _i an azimuth difference .DELTA.c _i of the azimuth angle cb _i is less than the threshold value C. On the other hand, when the influence of the magnetic source 202 is strong, it is not possible to capture geomagnetic successfully, misorientation .DELTA.c _i is greater than or equal to the threshold value C. Therefore, it is possible to easily detect the electronic compass error due to the influence of the magnetic source 202.

Also, calculated only when the influence of the magnetic source 202 is strong, the and the current angular difference d [theta] _i last from the previous output azimuth c _i-1 and the gyro sensor 107, the current output azimuth c _i of the main body To do. Here, the previous output azimuth angle c _i-1 is a normal azimuth angle obtained from the electronic compass when the influence of the magnetic source 202 is weak. Further, since the angle difference dθ _i obtained from the gyro sensor 107 is obtained from the previous angle and the current angle, the accumulation of errors by the gyro sensor 107 is kept to the minimum necessary.

  Therefore, a highly accurate orientation can be obtained even at a point where the influence of the magnetic source 202 is strong. From the above, according to the present embodiment, the traveling direction of the moving body can be detected easily and with high accuracy.

  The azimuth detection method described in the present embodiment can be realized by executing a program prepared in advance by a computer. This program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, and a DVD, and is executed by being read from the recording medium by the computer. The program may be a medium that can be distributed through a network such as the Internet.

  In addition, the orientation detection apparatus 100 described in the present embodiment includes an application specific IC (hereinafter simply referred to as “ASIC”) such as a standard cell or a structured ASIC (Application Specific Integrated Circuit), or a PLD (Programmable) such as an FPGA. It can also be realized by Logic Device). Specifically, for example, the orientation detection device 100 can be manufactured by defining the functions of the orientation detection device 100 described above by HDL description, and logically synthesizing the HDL description and giving it to the ASIC or PLD.

It is explanatory drawing which shows the hardware constitutions of the azimuth | direction detection apparatus concerning this Embodiment. It is a top view which shows the channel | path inside a building. It is explanatory drawing (the 1) which shows the memory content of the table which shows the value obtained for every point shown in FIG. It is explanatory drawing (the 2) which shows the memory content of the table which shows the value obtained for every point shown in FIG. It is explanatory drawing (the 3) which shows the memory content of the table which shows the value obtained for every point shown in FIG. It is a block diagram which shows the functional structure of an azimuth | direction detection apparatus. It is a flowchart (the 1) which shows an azimuth angle detection process sequence. It is a flowchart (the 2) which shows an azimuth angle detection process sequence. It is a flowchart (the 3) which shows an azimuth angle detection process sequence.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Direction detection apparatus 106a 1st electronic compass 106b 2nd electronic compass 107 Gyro sensor 202 Magnetic source 601 Azimuth angle acquisition part 602 Azimuth difference calculation part 603 Judgment part 604 Detection part 605 Angle acquisition part 606 Angle difference calculation part 607 Azimuth angle Calculation unit 608 Current position specifying unit 609 Output unit

Claims (5)

A first electronic compass and a second electronic compass that are arranged apart from the apparatus body and output the same detection signal to the geomagnetism;
An azimuth difference between a first azimuth angle based on a detection signal output from the first electronic compass and a second azimuth angle based on a detection signal output from the second electronic compass is equal to or greater than a predetermined threshold value. A determination means for determining whether or not
A gyro sensor that detects a horizontal angular velocity of the apparatus body;
An angle acquisition means for acquiring an angle of a horizontal component of the apparatus main body based on a detection result of the gyro sensor based on a direction of a predetermined horizontal component;
When the azimuth difference is less than the predetermined threshold value, the first azimuth angle and the horizontal component angle are recorded, and the first azimuth angle is output as an azimuth angle,
When the azimuth difference becomes equal to or higher than the predetermined threshold value, said first azimuth angle which the misorientation is recorded immediately before the above predetermined threshold value, and, the azimuth difference is the predetermined Based on the difference between the angle of the horizontal component recorded immediately before the threshold value or more and the angle of the horizontal component recorded first after the azimuth difference exceeds the predetermined threshold value, the azimuth angle is calculated. Calculate and output ,
The first recorded immediately before the azimuth difference becomes greater than or equal to the predetermined threshold value during a period from when the azimuth difference becomes greater than or equal to the predetermined threshold value to less than the predetermined threshold value. An azimuth detection device that calculates and outputs an azimuth angle based on the difference between the azimuth angle, the difference, and the difference between horizontal component angles recorded continuously during the period . A detection means for detecting a current position of the apparatus main body,
2. The azimuth detecting device according to claim 1, wherein when the current position of the device main body is not detected by the detection means, the angular velocity in the horizontal direction of the device main body is detected by the gyro sensor.   The azimuth detecting device according to claim 1, wherein the gyro sensor is a vibration gyro.   The azimuth detecting device according to claim 1, wherein each of the first electronic compass and the second electronic compass includes an MI element as a geomagnetic sensor. A computer comprising: a first electronic compass and a second electronic compass that are spaced apart from the apparatus main body and output the same detection signal to the geomagnetism; and a gyro sensor that detects an angular velocity in the horizontal direction of the apparatus main body.
An azimuth difference between a first azimuth angle based on a detection signal output from the first electronic compass and a second azimuth angle based on a detection signal output from the second electronic compass is equal to or greater than a predetermined threshold value. Whether or not
Based on the detection result of the gyro sensor, obtain the angle of the horizontal component of the apparatus body with reference to the direction of the predetermined horizontal component,
When the azimuth difference is less than the predetermined threshold value, the first azimuth angle and the horizontal component angle are recorded, and the first azimuth angle is output as an azimuth angle,
When the azimuth difference becomes equal to or higher than the predetermined threshold value, said first azimuth angle which the misorientation is recorded immediately before the above predetermined threshold value, and, the azimuth difference is the predetermined Based on the difference between the angle of the horizontal component recorded immediately before the threshold value or more and the angle of the horizontal component recorded first after the azimuth difference exceeds the predetermined threshold value, the azimuth angle is calculated. Calculate and output ,
The first recorded immediately before the azimuth difference becomes greater than or equal to the predetermined threshold value during a period from when the azimuth difference becomes greater than or equal to the predetermined threshold value to less than the predetermined threshold value. An azimuth detection program that executes a process of calculating and outputting an azimuth angle based on a difference between the azimuth angle, the difference, and a difference between horizontal component angles continuously recorded during the period .

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