JP2018112538A - Position estimation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position estimation system capable of reducing infrastructure installation cost. A position estimation system 1 includes a generation device 10 for generating a field and a terminal 20. The generation device 10 includes a generation element 11 (field generation element), a drive unit 12 for moving the generation element 11, and a transmission unit 14 for transmitting rotation information of the generation element 11 to the terminal 20. The terminal 20 has a sensor 21 for detecting the field F generated by the generating element 11, a receiving unit 22 for receiving rotation information, and a sensor 21 for estimating the position of the terminal 20 with reference to the position of the generating element 11. Includes a field F detected by, and an estimation unit 24 that estimates the distance and angle between the generating element 11 and the terminal 20 based on the rotation information received by the receiving unit 22. [Selection diagram] Fig. 2

Description

  The present invention relates to a position estimation system.

  Conventionally, it is known that positioning of a terminal can be performed using a wireless local area network (LAN) (see, for example, Patent Document 1). As a method for accurately estimating the position of the terminal, a method using a plurality of transmitters such as a fingerprint method or a three-point positioning method is also known.

JP 2013-221943 A

Eugene Paperno, Ichiro Sasada, and Eduard Leonovich, `` A New Method for Magnetic Position and OrientationTracking '', IEEE TRANSACTIONS ON MAGNETICS, VOL. 37, NO. 4, JULY 2001.

  When a plurality of transmitters are used as in the fingerprint method, the number of transmitters that need to be installed increases, so infrastructure (hereinafter abbreviated as “infrastructure”) installation costs are required.

  This invention is made | formed in view of the said subject, and aims at providing the position estimation system which can reduce an infrastructure installation cost.

  A position estimation system according to an aspect of the present invention includes a generation apparatus that generates a field and a terminal. The position estimation system estimates a position of a terminal, the generation apparatus including a field generation element, a field generation, and the like. A drive unit that rotates the element; a transmission unit that transmits rotation information of the field generation element to the terminal; the terminal detects a field generated by the field generation element; and a reception unit that receives the rotation information And the distance between the field generation element and the detection unit based on the field detected by the detection unit and the rotation information received by the reception unit in order to estimate the position of the terminal with reference to the position of the generation device And an estimation unit for estimating an angle.

  In the above position estimation system, in order to estimate the position of the terminal with reference to the position of the generation device, based on the detected field and the received rotation information, the distance between the field generating element and the detection unit and The angle is estimated. By using the rotational movement of the field generating element in this way, the position of the terminal determined by the distance and angle from the generating apparatus can be estimated within the environment simply by installing a field generating apparatus including one field generating element, for example. can do. Therefore, the infrastructure installation cost can be reduced as compared with a method in which many transmitters are installed in the environment such as a fingerprint method.

  ADVANTAGE OF THE INVENTION According to this invention, the position estimation system which can reduce an infrastructure installation cost is provided.

It is a figure for demonstrating the outline | summary of the position estimation system which concerns on embodiment. It is a figure which shows the example of the block diagram of a production | generation apparatus and a terminal. It is a figure for demonstrating the principle of a position estimation. It is a figure for demonstrating the principle of a position estimation. It is a figure for demonstrating the principle of a position estimation. It is a figure which shows the example of arrangement | positioning of a magnet. It is a figure which shows the example of an asymmetrical magnet. It is a figure which shows the example of the magnitude | size of the magnetic field detected. It is a figure which shows the example of the magnet which rotates at unequal speed. It is a figure which shows the example of the magnitude | size of the magnetic field detected. It is a figure which shows the example of the magnitude | size of the magnetic field detected. It is a figure for demonstrating the principle of a position estimation. It is a figure for demonstrating the principle of a position estimation. It is a figure for demonstrating the principle of a position estimation. It is a figure for demonstrating the principle of a position estimation. It is a figure which shows the hardware structural example of an apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  First, with reference to FIG. 1, the outline | summary of the position estimation system which concerns on embodiment is demonstrated with a comparative example.

  FIG. 1A shows a schematic configuration of a position estimation system 1e according to a comparative example. The position estimation system 1e according to the comparative example includes a transmitter 2 and a terminal 20e. The transmitter 2 transmits a transmission signal such as a beacon signal. The terminal 20 e is a mobile communication terminal such as a smartphone carried by the user U, and receives a transmission signal from the transmitter 2. The terminal 20e estimates the distance Le between the transmitter 2 and the terminal 20e from the signal strength (reception strength) of the received transmission signal. In this case, with reference to the transmitter 2, it can be estimated that the terminal 20e is located at a distance Le from the transmitter 2, but the angle between the transmitter 2 and the terminal 20e cannot be estimated. Therefore, the position estimation system 1e according to the comparative example cannot estimate the position of the terminal 20e in two-dimensional coordinates with reference to the transmitter 2, for example.

  FIG. 1B shows a schematic configuration of the position estimation system 1 according to the embodiment. The position estimation system 1 according to the embodiment includes a generation device 10 and a terminal 20. The generation device 10 generates a field. Here, “field” is used to include an electromagnetic field, an ultrasonic field, and the like. Details will be described later with reference to FIG. 2 and subsequent figures, but the field generated by the generation apparatus 10 periodically varies. The terminal 20 can estimate the distance L and the angle α between the generation device 10 and the terminal 20 by detecting a field with periodic fluctuation. The distance L and the angle α are the distance and the angle of the terminal 20 in two-dimensional polar coordinates with the position of the generating device 10 as the origin when the generating device 10 and the terminal 20 are viewed in plan. As described above, the position estimation system 1 according to the embodiment is compared with the position estimation system 1e according to the comparative example in that both the distance L and the angle α between the generation device 10 and the terminal 20 are estimated. Is different.

  FIG. 2 shows an example of a block diagram of the generation device 10 and the terminal 20 included in the position estimation system 1 (FIG. 1). First, the generation device 10 will be described. The generation device 10 includes a generation element 11, a drive unit 12, a timer 13, and a transmission unit 14.

  The generation element 11 is an element that generates the above-described field (field generation element). The generating element 11 has directivity. That is, the size of the field generated when the generating element 11 is stationary varies depending on the direction viewed from the generating element 11. The directivity of the generating element 11 may be designed so that the field size is maximized in a specific direction.

  The generating element 11 may be an electromagnetic field generating source that generates an electromagnetic field or an ultrasonic generating source that generates an ultrasonic field. When the generating element 11 is an electromagnetic field generating source, a magnet such as a permanent magnet or an electromagnet may be used as the generating element 11. The magnet may have directivity capable of generating a large magnetic field in a specific direction. In addition, an antenna or a laser may be used as the generating element 11. The antenna and the laser may have directivity capable of generating a large electromagnetic field in a specific direction. When the generating element 11 is an ultrasonic wave generation source, various known ultrasonic elements may be used as the generating element 11. The ultrasonic element may have directivity capable of generating a large ultrasonic field in a specific direction.

  The drive unit 12 is a part that rotates the generating element 11. The rotation of the generating element 11 may be a periodic rotational movement. The periodic rotational motion here is not only a constant-speed rotational motion that rotates at a predetermined cycle, but also a rotational motion including constant-speed rotation in a plurality of different cycles (hereinafter referred to as “unequal-speed rotation for convenience”). Exercise)). The unequal speed rotational motion will be described later with reference to FIG. In the following description, constant speed rotational motion will be described as an example of periodic rotational motion unless otherwise specified. For example, the generating element 11 is attached to a motor, and the drive unit 12 rotates the generating element 11 by driving the motor. The drive unit 12 can control the movement of the generating element 11 and grasps information (rotation information) related to the rotation of the generating element 11. Examples of the rotation information are the rotation speed and rotation angle of the generating element 11. The rotation speed may be represented by an angular speed, a frequency, a period, or the like. The rotation angle may be an angle (azimuth angle) with a predetermined orientation (for example, any orientation of east, west, north, and south on the map) as a reference angle (0 degrees). Thereby, the rotation angle of the generating element 11 and the actual azimuth are associated. Here, the drive part 12 can grasp | ascertain the rotational speed, rotation angle, etc. of the generating element 11 in each time with reference to the time shown by the timer 13 mentioned later. Therefore, the rotation speed, the rotation angle, etc. (so-called rotation history information of the generating element 11) at each time can be used as the rotation information. Such rotation information may be stored in a storage device (not shown) in the generation device 10.

  The timer 13 holds the time. The resolution of the timer 13 may be, for example, a time sufficiently shorter than the rotation period of the generating element 11 (for example, several tenths, hundreds of times, or shorter). Here, the timer 13 is synchronized with a timer 23 included in the terminal 20 described later. The synchronization method is not particularly limited. For example, the generation apparatus 10 and the terminal 20 may receive common time information or a synchronization signal from an external server (not shown), or the generation apparatus 10 and the terminal 20 may be performed. It may be performed using communication between.

  The transmission unit 14 is a part that transmits the above rotation information to the terminal 20. A short-range wireless signal may be used as the transmission signal. A protocol, a modulation method, and the like of the transmission signal are not particularly limited, but a signal conforming to Bluetooth (registered trademark), Wi-Fi (registered trademark), or the like can be used. The generation element 11 generates an advertising packet based on the rotation information described above, and transmits (transmits) the generated advertising packet.

  Next, the terminal 20 will be described. The terminal 20 includes a sensor 21, a reception unit 22, a timer 23, and an estimation unit 24.

  The sensor 21 is a detection unit that detects a field generated by the generation element 11. The sensor 21 is configured to be able to detect the size of the field at a time interval that is sufficiently shorter than the rotation period of the generating element 11 (for example, a time interval that is tens of times, one hundredth, or shorter). The When the generating element 11 is a magnet, a magnetic sensor may be used as the sensor 21. The magnetic sensor may be a known magnetic sensor that can detect the magnitude of the magnetic field. The magnetic sensor may be a sensor that can also detect the direction of the magnetic field. When the generating element 11 is an antenna, an antenna device configured to receive an electromagnetic wave from the generating element 11 may be used as the sensor 21. The antenna device is configured to be able to detect the magnitude of the received electromagnetic wave. When the generating element 11 is a laser, a light receiving device configured to receive laser light from the generating element 11 may be used as the sensor 21. The light receiving device is configured to be able to detect the magnitude of the received laser beam. When the generating element 11 is an ultrasonic element, a sound receiving device configured to receive an ultrasonic wave from the generating element 11 may be used as the sensor 21. The sound receiving device is configured to be able to detect the magnitude of received ultrasonic waves.

  The reception unit 22 is a part that receives the above-described rotation information transmitted from the transmission unit 14 of the generation apparatus 10. When the transmitting unit 14 transmits (transmits) an advertising packet generated based on the rotation information, the receiving unit 22 receives the advertising packet.

  The timer 23 holds the time synchronized with the timer 13. The timer 23 may have the same resolution as the timer 13.

  The estimation unit 24 is a part for estimating the position of the terminal 20 with reference to the position of the generation device 10. Therefore, the estimation unit 24 determines the distance and angle between the generation element 11 of the generation device 10 and the sensor 21 of the terminal 20 based on the field detected by the sensor 21 and the rotation information received by the reception unit 22. Is estimated. Since the distance and the angle between the generation element 11 and the sensor 21 are substantially the same as the distance L and the angle α (FIG. 1) between the generation device 10 and the terminal 20, the estimation unit 24 uses the estimated generation element. 11 and the sensor 21 can be estimated as the distance L and the angle α between the generation device 10 and the terminal 20. By estimating the distance L and the angle α, the position of the terminal 20 determined by the distance L and the angle α from the generation device 10 is estimated.

  Specifically, the estimation by the estimation unit 24 includes at least one time indicated by the field size and detection time detected by the sensor 21 and the rotation information received by the reception unit 22 and the rotation of the generating element 11 at the time. Angle is used. The detection time of the sensor 21 is the time indicated by the timer 23 and is synchronized with the time indicated by the rotation information (the time indicated by the timer 13 of the generation device 10). Next, an estimation method by the estimation unit 24 using such information will be described with reference to FIGS.

FIG. 3 is a plan view of the generating element. In this example, the generating element is a rod-shaped magnet 11a. In the magnet 11a, a portion on one end side in the extending direction of the magnet 11a corresponds to the N pole, and a portion on the other end side corresponds to the S pole. It is assumed that the magnet 11a is rotating at an angular velocity ω. If the time is t, the rotation angle of the magnet 11a is ωt. FIG. 3 shows two two-dimensional coordinate systems of plane coordinates (x, y) and polar coordinates (r, θ) with the position of the magnet 11a as the origin. The angle θ can correspond to an azimuth angle. The x-axis positive / negative direction and the y-axis positive / negative direction of the plane coordinates (x, y) may be determined so as to correspond to, for example, each direction (east, west, north, south, etc.) on the map. Note that the various parameters shown in FIG. 3 correspond to parameters used when the change in the Z-axis direction is not considered among the parameters shown in the three-dimensional coordinate system as described in Non-Patent Document 1, for example. Can do. In the drawing, the r direction (same diameter direction) of the magnetic field generated by the magnet 11a at a point (r, ωt) whose distance from the origin is r and is located in the direction from the S pole side to the N pole side of the magnet 11a. ) Component is expressed as H _r ′, and the component in the θ direction (direction orthogonal to the same diameter direction) is expressed as H _T ′. In the figure, the r-direction component of the magnetic field at an arbitrary point (r, θ) represented by polar coordinates is represented as H _r , and the θ-direction component is represented as H _T. In this case, the rotation of the magnetic field at an arbitrary point (r, θ) expressed in the polar coordinate system is expressed as H _r = Hr′cos φ and H _T = H _{T ′} sin φ. However, φ = θ−ωt. At this time, each component of the magnetic field in the XY coordinate system is expressed by the following equations (1-1) to (1-3).

In this case, the norm H of the magnetic field is expressed by the following formula (2).

  In the above equation (2), when θ = ωt or θ = ωt + π, the norm H of the magnetic field becomes the maximum value. That is, there may be a relationship between the rotation angle ωt of the magnet 11a and the magnitude of the magnetic field. This principle will be described by applying it to the position estimation system 1 according to the present embodiment.

FIG. 4 shows a state where the terminal 20 is located in the field F generated by the magnet 11a. In the following description, it is assumed that the field F is a magnetic field. Since the magnet 11a is a rod-shaped magnet, the magnetic field generated by the magnet 11a is greatest at the position in the extending direction of the magnet 11a. Table sensor 21 of the terminal 20 (FIG. 2) the magnitude of the magnetic field to be detected, that the major axis and the magnetic field H _r, the ellipse minor axis and the magnetic field H _T is rotated by an angle theta, the following equation (3) Is done.

  In the above equation (3), the magnitude of the magnetic field detected by the sensor 21 is maximized when θ = ωt or θ = ωt + π. Note that when θ = ωt + π / 2 or θ = ωt + 3π / 2, the magnitude of the detected magnetic field is minimized.

  The timing when the magnitude of the magnetic field detected by the sensor 21 is maximum is the time when the terminal 20 is located in the extending direction of the magnet 11a, as shown in FIG.

  FIG. 5 is a diagram conceptually showing the relationship between the rotation angle ωt of the magnet 11a and the position where the magnitude of the magnetic field detected by the sensor 21 is maximum. When the rotation angle ωt of the magnet 11a changes, the position where the magnitude of the magnetic field becomes maximum moves. In this example, along the rotation direction of the magnet 11a, the position where the magnitude of the magnetic field becomes maximum also changes in the order of coordinates (r, θ1), (r, θ2), (r, θ3). In this case, if the sensor 21 stays at the same position, the magnitude of the magnetic field detected by the sensor 21 is maximized at a certain timing during one rotation of the magnet 11a.

  For example, if the sensor 21 is located at the coordinates (r, θ1), the magnitude of the magnetic field detected by the sensor 21 is maximized at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ1. In other words, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 is maximum indicates the angle θ1 between the magnet 11a and the sensor 21. If the sensor 21 is positioned at (r, θ2), the magnitude of the magnetic field detected by the sensor 21 is maximized at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ2. In other words, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 is maximum indicates the angle θ2 between the magnet 11a and the sensor 21. If the sensor 21 is located at the coordinates (r, θ3), the magnitude of the magnetic field detected by the sensor 21 is maximized at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ3. In other words, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 is maximum indicates the angle θ3 between the magnet 11a and the sensor 21. Thus, the angle between the magnet 11a and the sensor 21 can be estimated from the rotation angle ωt of the magnet 11a at the time when the magnetic field detected by the sensor 21 is maximum.

  Returning to FIG. 2 again, as described above, the rotation information received by the receiving unit 22 of the terminal 20 includes the rotation speed and rotation angle of the magnet 11a at each time t. Since the period (rotation period) in which the magnet 11a makes one rotation is known from the rotation speed (for example, the angular speed ω), the estimation unit 24 is the same as the time when the magnitude of the magnetic field detected by the sensor 21 becomes the maximum during the rotation period. The rotation angle of the magnet 11a at the time (or the nearest time) is extracted from the rotation information. The estimation unit 24 estimates the extracted rotation angle as an angle between the magnet 11 a and the sensor 21. Thereby, the angle α between the generation apparatus 10 and the terminal 20 is also estimated.

  As described above with reference to FIGS. 3 and 4, the magnitude of the magnetic field detected by the sensor 21 during one rotation of the bar-shaped magnet 11a having a symmetrical magnetic field magnitude (intensity). There can be two local maxima. When the two maximum values have the same magnitude, there are also two times when the magnitude of the magnetic field detected by the sensor 21 becomes maximum during the rotation period. In this case, two angles different from each other by 180 degrees are estimated as the angle between the generating element 11 and the sensor 21, and any of these angles is an estimated value of the angle between the generating element 11 and the sensor 21. It is necessary to determine whether the correct answer value indicates. Next, an example of a technique for solving this will be described with reference to FIGS.

  In the example shown in FIG. 6, a wall W is provided near the magnet 11a. In this case, since the sensor 21 of the terminal 20 cannot be located in the direction from the magnet 11a to the wall W, the angle indicating that the sensor 21 is located in the direction from the magnet 11a to the wall W among the two estimated angles. And the remaining angles may be adopted as correct values.

  In the example shown in FIG. 7, a magnet having asymmetric magnetic field magnitude (strength) is used as the generating element 11. An example of a magnet whose strength is symmetric is a magnet having a shape in which the area of a part constituting one pole is smaller than the area of a part constituting the other pole. Since the magnetic flux density on the one pole side is larger than the magnetic flux density on the other pole side, that is, the magnetic field, the magnitudes of the magnetic fields on both poles are different (symmetric). In the magnet 11b shown in FIG. 7, the portion constituting the N pole has a bar shape. On the other hand, the part which comprises S pole has a fan shape which spreads as it leaves | separates from the part which comprises N pole. The magnet 11b may have a circular shape as a whole when viewed in plan. In this case, the N pole part and the S pole part are made of a magnetic material, and the remaining part is made of an insulator D such as plastic. Note that the magnet 11b may be configured without the insulator D. FIG. 8 shows an example of the magnitude of the magnetic field detected by the sensor 21 of the terminal 20 when the magnet 11b shown in FIG. 7 is rotated at a constant speed. The horizontal axis of the graph indicates time, and the vertical axis indicates magnetic field strength. In the graph, the rotation period of the magnet 11b is shown as a period T. Although the magnetic field intensity shows a maximum value at time t1 and time t2, the maximum value at time t1 is larger than the maximum value at time t2 by ΔH due to the asymmetry of the magnet 11b. By generating an extreme intensity difference in this way, it is possible to uniquely specify the time (azimuth angle of the terminal 20) at which the magnitude of the magnetic field detected by the sensor 21 becomes maximum during the rotation period of the magnet 11b. it can.

  In the example shown in FIG. 9, the drive unit 12 rotates at an unequal speed with respect to the magnet. For example, during one rotation of the magnet, the rotation speed of the magnet is switched to two or more different rotation speeds. In this case, since a magnet having a symmetrical magnetic field may be used, FIG. 9 shows the magnet 11a having the rod shape described above. In this example, while the rotation angle of the magnet 11a is not less than 0 and less than π (the first half rotation), the magnet 11a rotates at a relatively large rotation speed (for example, a short wavelength having a frequency of 3 Hz). While the rotation angle of the magnet 11a is not less than π and less than 2π (half rotation in the second half), the magnet 11a rotates at a relatively low rotation speed (for example, a long wavelength having a frequency of 1 Hz). FIG. 10 shows an example of the magnitude of the magnetic field detected by the sensor 21 of the terminal 20 when the magnet 11a is rotated at an unequal speed as shown in FIG. The horizontal axis of the graph indicates time, and the vertical axis indicates magnetic field strength. In the graph, the rotation period of the magnet 11b is shown as a period T. Of the period T, the first half rotation has a relatively large rotation speed, and the waveform has a short wavelength. Of the period T, the latter half rotation has a relatively low rotation speed, and the waveform has a long wavelength. Although the magnetic field intensity shows the maximum value (peak) at time t11 and time t12, the waveform near time t11 and the waveform near time t12 are different due to unequal speed rotation of the magnet 11b. In this case, the time Δt1 between one time t11 at which the magnetic field intensity reaches a peak and the time at which the magnetic field intensity becomes zero immediately before or immediately after the other time t12 at which the magnetic field intensity reaches a peak and immediately before or Immediately after that, it is shorter than the time Δt2 between the time when the magnetic field strength becomes zero. For example, if it is previously set in the system whether the peak corresponding to the shorter time Δt1 (that is, time t11) corresponds to the N-pole side or the S-pole side of the magnet 11a, the sensor is detected at time t11. It can be estimated in which direction 21 is located with respect to the magnet 11a. Thus, by generating the wavelength difference, the azimuth angle of the terminal 20 can be uniquely specified.

  In the example shown in FIG. 11, the rotation speed is switched every time the magnet 11a rotates once. In this example, the magnet 11a has a relatively high rotational speed during the first rotation, and the waveform has a short wavelength. The next one rotation has a relatively low rotation speed, and the waveform has a long wavelength. In the next one rotation, the rotation speed increases again, and the wavelength of the waveform becomes a short wavelength. Time t21 and time t23 are peaks immediately after switching from the long wavelength to the short wavelength. Time t22 is a peak immediately after switching from a short wavelength to a long wavelength. For example, the system determines whether the peak immediately after the rotation speed is switched from a short wavelength to a long wavelength (or from a long wavelength to a short wavelength) corresponds to the angle on the N pole side or the S pole side of the magnet 11a. In this case, it is possible to estimate in which direction the sensor 21 is located with respect to the magnet 11a at that time. In this way, the azimuth angle of the terminal 20 can be uniquely specified. In the example shown in FIG. 11, the rotation speed is switched every time the magnet 11a rotates once. However, the rotation speed may be switched every time the magnet 11a rotates twice or more. Such a technique is useful when it is difficult to switch the rotation period of the magnet 11a during one rotation as described above with reference to FIGS. In particular, when the magnet 11a is rotated at a high speed, it may be difficult to finely switch the rotation period of the magnet 11a due to the presence of an inertia moment.

  The above description is a method for estimating the angle between the generating element 11 and the sensor 21 when the generating element 11 is the magnet 11a. However, the generating element 11 has the directivity as described above. In the case of an antenna, a laser, or an ultrasonic wave generation source, the angle between the generation element 11 and the sensor 21 can be estimated based on the same principle.

  Returning to FIG. 2 again, the estimation unit 24 also estimates the distance between the generation element 11 and the sensor 21. The distance is estimated based on the size of the field detected by the sensor 21. The method for estimating the distance from the size of the detected field is not particularly limited. For example, a function or table in which the detected field size and distance are associated with each other may be created in advance and stored in a storage device (not shown) in the terminal 20. The estimation unit 24 can estimate the distance between the generation element 11 and the sensor 21 based on the size of the field detected by the sensor 21 by referring to such a function or table.

  Here, in the position estimation system 1, the generating element 11 is rotating. Therefore, the size of the field used for the above-described distance estimation may be a value determined based on the size of a plurality of fields detected by the sensor 21. As such a value, for example, an average value of the sizes of a plurality of fields detected by the sensor 21 over the rotation period of the generating element 11 may be used. An average value over a plurality of rotation cycles may be used.

  Using the method described above, the estimation unit 24 estimates the angle and distance between the generation element 11 and the sensor 21. As described above, the distance L and the angle α (FIG. 1) between the generation device 10 and the terminal 20 are estimated by estimating the angle and distance between the generating element 11 and the sensor 21. Thereby, the estimation part 24 can estimate the position of the terminal 20 defined by the distance L from the generation device 10 and the angle α. For example, if the actual position (such as coordinates on the map) of the generation device 10 is known, the actual position of the terminal 20 can also be estimated.

  The example in which the estimation unit 24 estimates the angle between the generation element 11 and the sensor 21 on the XY plane using the rotation of the generation element 11 on the XY plane has been described above. However, the estimation unit 24 can also estimate the angle between the generation element 11 and the sensor 21 in a plane (for example, the XZ plane) intersecting the XY plane, using the rotation of the generation element 11 in the XY plane. . Below, the case where the generating element 11 is the magnet 11a is demonstrated.

In the XZ plane shown in FIG. 12, the position of the sensor 21 with the position of the magnet 11a as the origin is represented by polar coordinates (r, ψ) on the XZ plane. The z-axis positive direction of the plane coordinates (x, z) is determined so as to correspond to the vertically upward direction, for example. That is, the angle θ described above (FIG. 3 and the like) can correspond to an azimuth angle, whereas the angle ψ can correspond to an elevation angle. The polar coordinates (r, ψ) shown in FIG. 12 are coordinates under the condition of θ = 0 in the three-dimensional polar coordinates (r, θ, ψ). The three-dimensional coordinates may be the same as the three-dimensional coordinates described in Non-Patent Document 1, for example. In the figure, r direction component of the magnetic field at distance r is represented as H _r, [psi direction component is expressed as H _T.

  FIG. 13 is a diagram conceptually showing the magnetic field generated by the magnet 11a using magnetic lines of force. As shown in FIG. 13, as the angle ψ approaches 0 to π / 2, the angle formed between the tangential direction of the magnetic field lines and the XY plane changes from 0 to π. As the angle ψ increases, the magnitude of the magnetic field component in the XY plane direction is expected to gradually decrease, become zero at a certain point, and then decrease further (in the opposite direction).

  FIG. 14 is a diagram conceptually showing how the sensor 21 of the terminal 20 detects the magnetic field (field F) generated by the magnet 11a. As shown in FIG. 14, the angle formed by the ellipse generated by the magnetic field vector generated by the magnet 11a at each point and the xy plane depends on the angle ψ (however, it can also depend on the distance). At the point of angle ψ = ± π / 2, the same magnetic vector only rotates, so that the ellipse is predicted to be circular. In addition, at any angle, it is predicted that there is a moment when the minor axis of the ellipse faces directly beside.

Based on the above, a method for estimating the angle ψ from the magnetic field generated by the magnet 11a will be examined in accordance with the following policy. First, only the case of θ = 0 is considered from the symmetry of the magnetic field. The azimuth angle (angle θ) can be estimated based on the information on the norm of the magnetic field as described above with reference to FIGS. 3 to 6, whereas the elevation angle (angle ψ) is estimated. Each information of the x-axis direction component, y-axis direction component, and z-axis direction component is required. The formula for estimating the final angle [psi, H _r and H _T does not contain (i.e. angle from only the values of the sensor 21 [psi can be estimated) is desirable. In addition, when the coordinate system of the magnet 11a and the coordinate system of the terminal 20 are different, coordinate conversion is necessary, but first, the case where both coordinate systems match is considered.

H _z , H _y , and H _z are represented by the following formulas (4-1) to (4-3).

In the above formula (4-1) to (4-3), by substituting .omega.t = 0 to _{H x} and _{H z,} and substituting ωt = π / 2 in _{H y,} the following equation (5-1) - (5-3).

Clearing the _{H r} and _{H T} from the above equation (5-1) to (5-3), the angle ψ can be determined from the following equation (6). In the equation _{(6), H x (ωt} = 0) is the _{H x} when the _{ωt = 0, H y (ωt} = π / 2) is _{H y} in the case of ωt = π / 2, H _{z (ωt = 0)} is H _z when ωt = 0.

  When obtaining the angle ψ from the above equation (6), first, it should be noted that two cos ψ are obtained because the magnetic field takes the maximum value and the minimum value twice while the magnet 11a rotates once. It is. This problem can be solved by using a method of providing a wall W near the magnet 11a as described above with reference to FIG.

Next, it should be noted that there are two values (± ψ) of the angle ψ determined from cos ψ. Whether the angle ψ is positive or negative can be specified from the sign of _Hz . For example, as shown in FIG. 15, the N pole side of the magnet 11a corresponds to the sign of the sign of the H _z is [psi, it is reversed relationship in S-pole side.

  When the angle ψ is ± (π / 2), the above formula (6) cannot be used. However, this can be solved by using, for example, the following formula (7).

Explaining the above principle by applying it to the position estimation system 1, the estimation unit 24 of the terminal 20 firstly, H _{x at} the time when the norm of the magnetic field detected by the sensor 21 during the one rotation of the generating element 11 is the maximum value. , H _z, and H _y at the time when the norm is the minimum value are acquired. The sensor 21 in this case is a sensor (for example, a three-axis sensor) that can detect H _x , H _y and H _z . Next, the estimation unit 24 obtains cos ψ using the above equation (6), and further obtains an angle ψ from cos ψ. At this time, the estimation unit 24 employs + ψ when H _z is positive, and employs −ψ when H _z is negative. In this way, the estimation unit 24 estimates the angle ψ.

  When the estimation unit 24 further estimates the elevation angle (angle ψ) as well as the distance (distance r) and azimuth angle (angle θ) between the generation element 11 and the sensor 21, the generation element 11 The terminal 20 in the three-dimensional coordinates with reference to the position of can be estimated.

Here, the norm of the magnetic field detected by the sensor 21 at the position of the three-dimensional coordinate system (r, 0, ψ) when θ = 0 can be expressed by the following equation (7).

Also in the above equation (7), as in the case of equation (3) described above, the magnetic field norm is the minimum value when ωt = π / 2, 3π / 2, and when ωt = 0, π. In addition, the norm of the magnetic field is the maximum value. The minimum value H _min and the maximum value H _max of the norm are expressed by the following formulas (8-1) and (8-2).

Specifically, the magnitude of the magnetic field detected by the sensor 21 of the terminal 20 is expressed by the following equation (9).

From the above equation (9), the x-axis direction component, the y-axis direction component, and the z-axis direction component of the magnetic field at the position (r, 0, ψ) of the sensor 21 have the diameters in the x-axis and z-axis directions: (10), and ellipsoid having a diameter in the y-axis direction H _'T is can be deemed to have rotated by ψ the y-axis as a rotation axis.

Further, when θ ≠ 0, conversion may be performed as in the following equations (11-1) and (11-2).

By substituting the above formulas (11-1) and (11-2) into the above formula (9), the following formula (12) is obtained.

  The above expression (12) is a general expression of the x-axis direction component, the y-axis direction component, and the z-axis direction component of the magnetic field at the position (r, θ, ψ) of the sensor 21.

  In the position estimation system 1 described above, in order to estimate the position of the generation device 10 based on the position of the generation element 11, the field F detected by the sensor 21 and the generation element 11 received by the reception unit 22 in the terminal 20. The distance and angle between the generation element 11 and the sensor 21 are estimated based on the rotation information regarding the rotation of the sensor 21. If the rotational movement of the generating element 11 is used in this way, the position of the terminal 20 determined by the distance L and the angle α from the generating device 10 is estimated within the environment only by installing one generating element 11, for example. be able to. Therefore, the infrastructure installation cost can be reduced as compared with a method in which many transmitters are installed in the environment such as a fingerprint method.

  The rotation information related to the rotation of the generation element 11 includes the time and the rotation angle ωt of the generation element 11. The estimation unit 24 receives the size and detection time of the field F detected by the sensor 21 and the reception unit 22. The distance and angle between the generation element 11 and the sensor 21 may be estimated based on the time and the rotation angle ωt included in the rotation information. Thereby, the position of the terminal 20 can be estimated only by transmitting the time and the rotation angle ωt of the generation element 11 as rotation information from the transmission unit 14 of the generation device 10 to the reception unit 22 of the terminal 20.

  The generation element 11 may be an electromagnetic field generation source that generates at least one of an electric field and a magnetic field, or an ultrasonic generation source that generates ultrasonic waves. Thereby, the position of the terminal 20 can be estimated by a simple method using the rotation of the electromagnetic field generation source or the ultrasonic generation source.

  The electromagnetic field generating source may be a magnet that generates a magnetic field, or an antenna or laser that emits electromagnetic waves. When the electromagnetic field generation source is a magnet, the electromagnetic field generation source itself can also have a simple configuration. In addition, when an antenna or a laser is used, there is a possibility that an error occurs in the estimated distance due to the influence of reflection and absorption of electromagnetic waves. However, in the case of a magnet, there is no such influence. And the error of the estimation accuracy of the distance between the sensor 21 and the estimation accuracy of the position of the terminal 20 can be reduced. When the electromagnetic wave generation source is an antenna or a laser, there is an advantage that, for example, the frequency of the field (in this case, the electromagnetic field) can be set to a desired value to increase the degree of freedom in designing the apparatus.

  When the generating element 11 is the magnet 11a, the distance (distance r), the azimuth angle (angle θ), and the elevation angle (angle ψ) between the generating element 11 and the sensor 21 can be estimated. The terminal 20 in the three-dimensional coordinates based on the position of 11 can also be estimated.

  In the above-described embodiment, the rotation information transmitted from the generation device 10 to the terminal 20 includes not only the rotation angle of the generating element 11 but also the rotation speed, and the estimation unit 24 in the terminal 20 includes the rotation speed. An example in which the above-described estimation is performed using also the above has been described. However, the rotation information may not include the rotation speed. Even in that case, for example, if the rotation speed of the generating element 11 is set to a known value in the position estimation system 1, the estimation unit 24 of the terminal 20 performs the above-described estimation using the set rotation speed. be able to.

  Finally, an example of the hardware configuration of the terminal 20 of the present invention will be described with reference to FIG. The terminal 20 may be physically configured as a computer device including a processor 20A, a memory 20B, a storage 20C, a communication module 20D, an input device 20E, an output device 20F, a bus 20G, and the like. The functional block (configuration unit) of the terminal 20 is realized by any combination of hardware and / or software. Further, the means for realizing each functional block is not particularly limited. In other words, each functional block may be realized by one device physically and / or logically coupled, or two physically and / or logically separated two wired and / or wirelessly linked to each other. You may implement | achieve with the above apparatus.

  In the following description, the term “apparatus” can be read as a circuit, a device, a unit, or the like. The hardware configuration of the terminal 20 may be configured to include one or a plurality of devices illustrated in the figure, or may be configured not to include some devices.

  Each function in the terminal 20 is obtained by reading predetermined software (program) on hardware such as the processor 20A and the memory 20B, so that the processor 20A performs an operation and performs communication by the communication module 20D, data in the memory 20B and the storage 20C. This is realized by controlling reading and / or writing.

  Although the present embodiment has been described in detail above, it will be apparent to those skilled in the art that the present embodiment is not limited to the embodiment described in this specification. The present embodiment can be implemented as a modification and change without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present embodiment.

  Note that the terms described in this specification and / or terms necessary for understanding this specification may be replaced with terms having the same or similar meaning.

  As used herein, the phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” means both “based only on” and “based at least on.”

  These terms are similar to the term “comprising” as long as “include”, “including” and variations thereof are used herein or in the claims. It is intended to be comprehensive. Furthermore, the term “or” as used herein or in the claims is not intended to be an exclusive OR.

  In this specification, a plurality of devices are also included unless there is only one device that is clearly present in context or technically.

  DESCRIPTION OF SYMBOLS 1 ... Position estimation system, 10 ... Generator, 11 ... Generating element, 12 ... Drive part, 13 ... Timer, 14 ... Transmitter, 20 ... Terminal, 21 ... Sensor, 22 ... Receiver, 23 ... Timer, 24 ... Estimation Part, F ... field.

Claims (6)

A position estimation system for estimating a position of the terminal, comprising a generation device for generating a field and a terminal,
The generator is
A field-generating element;
A driving unit for rotating the field generating element;
A transmission unit for transmitting rotation information of the field generation element to the terminal;
Including
The terminal
A detection unit for detecting a field generated by the field generation element;
A receiving unit for receiving the rotation information;
Based on the field detected by the detecting unit and the rotation information received by the receiving unit, the field generating element and the detection are estimated to estimate the position of the terminal with respect to the position of the generating device. An estimation unit for estimating a distance and an angle between the unit,
including,
Position estimation system. The rotation information includes a time and a rotation angle of the field generating element,
The estimation unit includes the field generation element and the detection unit based on the size and detection time of the field detected by the detection unit and the time and rotation angle included in the rotation information received by the reception unit. Estimate the distance and angle between
The position estimation system according to claim 1. The field generating element is an electromagnetic field source that generates at least one of an electric field and a magnetic field, or an ultrasonic source that generates ultrasonic waves.
The position estimation system according to claim 1 or 2. The electromagnetic field generation source is a magnet that generates a magnetic field, or an antenna or laser that radiates electromagnetic waves.
The position estimation system according to claim 3. The electromagnetic field generation source is a magnet having asymmetric strength,
The drive unit rotates the magnet having asymmetric strength at a constant speed,
The position estimation system according to claim 4. The electromagnetic field generation source is a magnet having a symmetrical strength,
The drive unit is intended for a magnet having a symmetrical strength, and performs a rotational motion including a constant speed rotation at a plurality of different periods.
The position estimation system according to claim 4.

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