JP7012991B2 - Position estimation system - Google Patents

Description

The present invention relates to a position estimation system.

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

Japanese Unexamined Patent Publication No. 2013-221943

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

If multiple transmitters are used, such as in the fingerprint method, the number of transmitters that must be installed increases, so infrastructure (hereinafter abbreviated as "infrastructure") installation costs are incurred.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a position estimation system capable of reducing infrastructure installation costs.

The position estimation system according to one aspect of the present invention is a position estimation system for estimating the position of a terminal, which comprises a generation device for generating a field and a terminal, and the generation device includes a field generation element and a field generation. The terminal includes a driving unit for rotating the element and a transmitting unit for transmitting rotation information of the field generating element to the terminal, and the terminal has a detecting unit for detecting the field generated by the field generating element and a receiving unit for receiving the rotation information. And, in order to estimate the position of the terminal with respect to the position of the generator, the distance between the field generating element and the detection unit based on the field detected by the detection unit and the rotation information received by the reception unit. And an estimation unit that estimates the angle, and includes.

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

According to the present invention, a position estimation system capable of reducing infrastructure installation costs is provided.

It is a figure for demonstrating the outline of the position estimation system which concerns on embodiment. It is a figure which shows the example of the block diagram of the generator and the terminal. It is a figure for demonstrating the principle of position estimation. It is a figure for demonstrating the principle of position estimation. It is a figure for demonstrating the principle of position estimation. It is a figure which shows the arrangement example of a magnet. It is a figure which shows the example of the asymmetric magnet. It is a figure which shows the example of the magnitude of the detected magnetic field. It is a figure which shows the example of the magnet which rotates at an unequal speed. It is a figure which shows the example of the magnitude of the detected magnetic field. It is a figure which shows the example of the magnitude of the detected magnetic field. It is a figure for demonstrating the principle of position estimation. It is a figure for demonstrating the principle of position estimation. It is a figure for demonstrating the principle of position estimation. It is a figure for demonstrating the principle of position estimation. It is a figure which shows the hardware configuration example of the 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 designated by the same reference numerals, and duplicate description will be omitted.

First, with reference to FIG. 1, the outline of the position estimation system according to the embodiment will be described together 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 the transmitter 2 and the terminal 20e. The transmitter 2 transmits a transmission signal such as a beacon signal. The terminal 20e 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, it can be estimated that the terminal 20e is at a position separated from the transmitter 2 by a distance Le with respect to 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 the two-dimensional coordinates with respect 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 generator 10 generates a field. Here, the term "field" is used to include an electromagnetic field, an ultrasonic field, and the like. The details will be described later with reference to FIGS. 2 and 2, but the fields generated by the generation device 10 vary periodically. The terminal 20 can estimate the distance L and the angle α between the generation device 10 and the terminal 20 by detecting the field accompanied by the periodic fluctuation. The distance L and the angle α are the distance and the angle of the terminal 20 in the two-dimensional polar coordinates with the position of the generation device 10 as the origin when the generation device 10 and the terminal 20 are viewed in a plan view. 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. It's 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 generator 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 (field generation element) that generates the above-mentioned field. The generating element 11 has directivity. That is, the size of the field generated when the generating element 11 is stationary differs depending on the direction seen from the generating element 11. The directivity of the generating element 11 may be designed so that the size of the field is the largest in a particular direction.

The generating element 11 may be an electromagnetic field generating source that generates an electromagnetic field or an ultrasonic wave 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 can have directivity capable of generating a large magnetic field in a particular direction. In addition, an antenna or a laser may be used as the generating element 11. Antennas and lasers can have directivity capable of generating large electromagnetic fields in a particular direction. When the generating element 11 is an ultrasonic 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 portion that rotates the generating element 11. The rotation of the generating element 11 may be a periodic rotational movement. The periodic rotational motion referred to here is not only a constant velocity rotational motion of rotating in one predetermined cycle, but also a rotational motion including constant velocity rotation in a plurality of different cycles (hereinafter, "non-constant velocity rotation" for convenience). "Exercise") is also included. The non-constant speed rotational motion will be described later with reference to FIG. 9 and the like. In the following, unless otherwise specified, a constant velocity rotational motion will be described as an example as a periodic rotational motion. For example, the generating element 11 is attached to a motor, and the driving unit 12 rotates the generating element 11 by driving the motor. The drive unit 12 can control the motion of the generating element 11 and grasps information (rotation information) regarding the rotation of the generating element 11. Examples of rotation information are the rotation speed, rotation angle, and the like of the generating element 11. The rotation speed may be expressed by an angular velocity, a frequency, a period, or the like. The rotation angle may be an angle (azimuth angle) with a predetermined direction (for example, any of the north, south, east, and west directions on the map) as a reference angle (0 degree). As a result, the rotation angle of the generating element 11 is associated with the actual orientation. Here, the drive unit 12 can grasp the rotation speed, rotation angle, and the like of the generating element 11 at each time by referring to the time indicated by the timer 13 described later. Therefore, the rotation speed, the rotation angle, and the like (so to speak, the history information of the rotation of the generating element 11) at each time can be used as the rotation information. Such rotation information can 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 cycle of the generating element 11 (for example, a time of several tenths, a few hundredths, or shorter). Here, the timer 13 is synchronized with the timer 23 included in the terminal 20 described later. The synchronization method is not particularly limited, but may be performed by, for example, the generator 10 and the terminal 20 receiving common time information or a synchronization signal from an external server (not shown), or the generator 10 and the terminal 20. It may be done using communication with.

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

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

The sensor 21 is a detection unit that detects a field generated by the generating element 11. The sensor 21 is configured to be able to detect the size of the field at a time interval sufficiently shorter than the rotation cycle of the generating element 11 (for example, a time interval of a few tenths, a few hundredths, or a shorter time interval). To. 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 capable of detecting 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 the 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 the 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 light. When the generating element 11 is an ultrasonic element, a sound receiving device configured to receive ultrasonic waves 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 the received ultrasonic wave.

The receiving unit 22 is a unit that receives the above-mentioned rotation information transmitted from the transmitting unit 14 of the generation device 10. When the transmitting unit 14 transmits (transmits) the advertising packet generated based on the rotation information, the receiving unit 22 receives the advertising packet.

The timer 23 holds a 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 respect to the position of the generation device 10. Therefore, the estimation unit 24 has a distance and an angle between the generating element 11 of the generator 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 receiving unit 22. To estimate. Since the distance and angle between the generating element 11 and the sensor 21 are substantially the same as the distance L and the angle α (FIG. 1) between the generating device 10 and the terminal 20, the estimation unit 24 has estimated the generating element. The distance and angle between the 11 and the sensor 21 can be estimated as the distance L and the angle α between the generator 10 and the terminal 20. By estimating these distance L and angle α, the position of the terminal 20 determined by the distance L and angle α from the generator 10 is estimated.

Specifically, the estimation by the estimation unit 24 includes the size and detection time of the field detected by the sensor 21, at least one time shown in the rotation information received by the reception unit 22, and the rotation of the generating element 11 at that time. Angle and 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 generator 10). The estimation method by the estimation unit 24 using the information will be described next with reference to FIGS. 3 to 6.

FIG. 3 is a plan view of the generated element. In this example, the generating element is a rod-shaped magnet 11a. In the magnet 11a, the portion on one end side of the magnet 11a in the extending direction corresponds to the N pole, and the 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. Assuming that 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 the azimuth angle. The x-axis positive / negative direction and the y-axis positive / negative direction of the plane coordinates (x, y) may be set so as to correspond to each direction (east, west, north, south, etc.) on the map, for example. The various parameters shown in FIG. 3 correspond to the parameters used when the change in the Z-axis direction is not taken into consideration among the parameters shown in the three-dimensional coordinate system as described in Non-Patent Document 1, for example. Can be. In the figure, at a point (r, ωt) where the distance from the origin is r and the magnet 11a is located in the direction from the S pole side to the N pole side, the magnetic field generated by the magnet 11a is in the r direction (same radial direction). ) Is represented as H _r ′, and the component in the θ direction (direction orthogonal to the same radial direction) is represented as _HT ′. Further, in the figure, the component in the r direction of the magnetic field at an arbitrary point (r, θ) represented by polar coordinates is represented as H _r , and the component in the θ direction is represented as _HT . In this case, the rotation of the magnetic field at an arbitrary point (r, θ) represented in the polar coordinate system is represented as H _r = _Hr'cosφ , HT = _HT'sinφ . However, φ = θ−ωt. At this time, each component of the magnetic field in the XY coordinate system is represented by the following equations (1-1) to (1-3).

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

In the above equation (2), the norm H of the magnetic field becomes the maximum value when θ = ωt or θ = ωt + π. 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 how the terminal 20 is located in the field F generated by the magnet 11a. Hereinafter, 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 becomes the largest at the position in the extending direction of the magnet 11a. The magnitude of the magnetic field detected by the sensor 21 (FIG. 2) of the terminal 20 is _expressed by the following equation (3) in which an ellipse having a major axis as a magnetic field _Hr and a minor axis as a magnetic field HT is rotated by an angle θ. Will be 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. When θ = ωt + π / 2 or θ = ωt + 3π / 2, the magnitude of the detected magnetic field becomes the minimum.

As shown in FIG. 4, the timing at which the magnitude of the magnetic field detected by the sensor 21 becomes maximum is the time when the terminal 20 is located in the extending direction of the magnet 11a.

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 maximized. When the rotation angle ωt of the magnet 11a changes, the position where the magnitude of the magnetic field becomes maximum also moves. In this example, the position where the magnitude of the magnetic field becomes maximum also changes in the order of the coordinates (r, θ1), (r, θ2), (r, θ3) along the rotation direction of the magnet 11a. In this case, if the sensor 21 stays at the same position, the magnitude of the magnetic field detected by the sensor 21 becomes maximum 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 becomes maximum at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ1. Conversely, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 becomes maximum indicates the angle θ1 between the magnet 11a and the sensor 21. If the sensor 21 is located at (r, θ2), the magnitude of the magnetic field detected by the sensor 21 becomes maximum at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ2. Conversely, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 becomes 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 becomes maximum at the timing when the rotation angle ωt of the magnet 11a becomes equal to θ3. Conversely, the rotation angle ωt of the magnet 11a at the time when the magnitude of the magnetic field detected by the sensor 21 becomes maximum indicates the angle θ3 between the magnet 11a and the sensor 21. In this way, 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 becomes 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, rotation angle, and the like of the magnet 11a at each time t. Since the period during which the magnet 11a makes one rotation (rotational cycle) can be known from the rotation speed (for example, the angular velocity ω), the estimation unit 24 is the same as the time when the magnitude of the magnetic field detected by the sensor 21 during the rotation cycle becomes maximum. 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 11a and the sensor 21. As a result, the angle α between the generator 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 rod-shaped magnet 11a having a symmetrical magnetic field magnitude (strength). There can be two maximum values. 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 during the rotation cycle becomes maximum. In this case, two angles different by 180 degrees are estimated as the angles between the generating element 11 and the sensor 21, and which of these angles is the estimated value of the angle between the generating element 11 and the sensor 21. It becomes necessary to judge whether it is the correct answer value indicating. An example of a method for solving this will be described next with reference to FIGS. 6 to 11.

In the example shown in FIG. 6, the 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 of the wall W from the magnet 11a, of the two estimated angles, the angle indicating that the sensor 21 is located in the direction of the wall W from the magnet 11a. Should be excluded and the remaining angle should be adopted as the correct answer value.

In the example shown in FIG. 7, a magnet having an asymmetric magnetic field magnitude (strength) is used as the generating element 11. An example of a magnet having a symmetrical strength is a magnet having a shape in which the area of a portion constituting one pole is smaller than the area of a portion constituting the other pole. Since the magnetic flux density on one pole side becomes larger and the magnetic flux density on the other pole side, that is, the magnetic field becomes larger, the magnitudes of the magnetic fields on both poles are different (symmetrical). In the magnet 11b shown in FIG. 7, the portion constituting the N pole has a rod shape. On the other hand, the portion constituting the S pole has a fan shape that expands as the distance from the portion constituting the N pole increases. The magnet 11b may have a circular shape as a whole when viewed in a plan view. In this case, the N-pole portion and the S-pole portion are made of a magnetic material, and the remaining portion is made of an insulator D such as plastic. The magnet 11b may also have a configuration that does not have 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 shows the time, and the vertical axis shows the magnetic field strength. In the graph, the rotation cycle of the magnet 11b is shown as the cycle T. The magnetic field strength shows a maximum value at time t1 and time t2, but the maximum value at time t1 is larger by ΔH than the maximum value at time t2 due to the asymmetry of the magnet 11b described above. By generating the 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 during the rotation cycle of the magnet 11b becomes maximum. can.

In the example shown in FIG. 9, the drive unit 12 rotates the magnet at an unequal speed. 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 magnitude may be used, FIG. 9 shows the magnet 11a having a rod shape described above. In this example, while the rotation angle of the magnet 11a is 0 or more and less than π (half rotation in the first half), 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 π or more and less than 2π (half rotation in the latter half), the magnet 11a rotates at a relatively small 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 shows the time, and the vertical axis shows the magnetic field strength. In the graph, the rotation cycle of the magnet 11b is illustrated as the cycle T. In the first half of the period T, the rolling speed is relatively large, and the waveform has a short wavelength. In the latter half of the period T, the rotation speed is relatively small, and the waveform has a long wavelength. The magnetic field strength shows the maximum value (peak) at time t11 and time t12, but the waveform near time t11 and the waveform near time t12 are different due to the unequal velocity rotation of the magnet 11b. In this case, the time Δt1 between the time t11 at which the magnetic field strength peaks and the time when the magnetic field strength becomes zero immediately before or after the peak is the time t12 immediately before or immediately after the other time t12 at which the magnetic field strength peaks. It is shorter than the time Δt2 between the time when the magnetic field strength becomes zero immediately afterwards. For example, if the system presets whether the peak corresponding to the shorter time Δt1 (that is, the time t11) corresponds to the north pole side or the south pole side of the magnet 11a, the sensor at the time t11. It is possible to estimate in which direction the 21 is located with respect to the magnet 11a. By generating the wavelength difference 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 each time the magnet 11a makes one rotation. In this example, the magnet 11a has a relatively high rotation speed in the first rotation, and the wavelength of the waveform is a short wavelength. The next rotation has a relatively low rotation speed, and the wavelength of the waveform is a long wavelength. In the next 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 a long wavelength to a short wavelength. Time t22 is the peak immediately after switching from the short wavelength to the long wavelength. For example, the system determines whether the peak immediately after the rotation speed is switched from the short wavelength to the long wavelength (or from the long wavelength to the short wavelength) corresponds to the angle on the north pole side or the angle on the south pole side of the magnet 11a. If it is set in advance in, 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, but the rotation speed may be switched every time the magnet 11a rotates two or more times. Such a method is useful when it is difficult to switch the rotation cycle of the magnet 11a during one rotation as described above with reference to FIGS. 9 and 10. In particular, when the magnet 11a is rotated at high speed, it may be difficult to finely switch the rotation cycle of the magnet 11a due to the existence of a moment of inertia or the like.

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

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

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

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

In the above, an example in which the estimation unit 24 estimates the angle between the generating element 11 and the sensor 21 in the XY plane by using the rotation of the generating element 11 in the XY plane has been described. However, the estimation unit 24 can also use the rotation of the generating element 11 in the XY plane to estimate the angle between the generating element 11 and the sensor 21 in a plane intersecting the XY plane (for example, the XZ plane). .. Hereinafter, a case where the generating element 11 is a magnet 11a will be described.

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) in the XZ plane. The z-axis positive direction of the plane coordinates (x, z) is determined to correspond to, for example, a vertically upward direction. That is, the angle θ (FIG. 3, etc.) described above can correspond to the azimuth angle, while the angle ψ can correspond to the 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 as described in Non-Patent Document 1, for example. In the figure, the component in the r direction of the magnetic field at the distance r is represented as H _r , and the component in the _ψ direction is represented as HT.

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

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 with the xy plane depends on the angle ψ (but can also depend on the distance). At the point of angle ψ = ± π / 2, it is predicted that the ellipse will be circular because the same magnetic vector only rotates. In addition, it is predicted that there will be a moment when the minor axis of the ellipse turns to the side at any angle.

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, from the symmetry of the magnetic field, consider only the case of θ = 0. The estimation of the azimuth angle (angle θ) can be performed based on the information of the norm of the magnetic field as described above with reference to FIGS. 3 to 6, whereas the estimation of the elevation angle (angle ψ) is performed by the magnetic field. Information on the x-axis direction component, the y-axis direction component, and the z-axis direction component of the above is required. It is desirable that the calculation formula for finally estimating the angle _ψ does not include H _r and HT (that is, the angle ψ can be estimated only from the value of the sensor 21). If the coordinate system of the magnet 11a and the coordinate system of the terminal 20 are different, coordinate conversion is required, but first, the case where both coordinate systems match will be examined.

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

Substituting ωt = 0 for H _x and H _z and ωt = π / 2 for _Hy in the above equations (4-1) to (4-3), the following equations (5-1) to (5-1) to It becomes (5-3).

By eliminating H _r and _HT from the above equations (5-1) to (5-3), the angle ψ can be obtained from the following equation (6). In equation (6), H _{x (ωt = 0)} is H _x when ωt = 0, and _{Hy (ωt = π / 2)} is _Hy when ωt = π / 2. H _{z (ωt = 0)} is H _z when ωt = 0.

When calculating the angle ψ from the above equation (6), it should be noted that the magnetic field takes the maximum value and the minimum value twice while the magnet 11a makes one rotation, so that two cos ψs to be obtained appear. Is. This problem is solved by using, for example, 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 also two (± ψ) values of the angle ψ obtained from cos ψ. Whether the angle _ψ has a positive or negative value can be specified from the sign of Hz. For example, as shown in FIG. 15, the code of Hz corresponds to the code of _ψ on the north pole side of the magnet 11a, and the relationship is opposite on the south pole side.

When the angle ψ is ± (π / 2), the above equation (6) cannot be used, but this can be solved by using, for example, the equation (7) described later.

To explain by applying the above principle to the position estimation system 1, first, the estimation unit 24 of the terminal 20 first H _x at the time when the norm of the magnetic field detected by the sensor 21 during one rotation of the generating element 11 is the maximum value. , H _z and the value of _Hy at the time when the norm is the minimum value is acquired. The sensor 21 in this case is a sensor (for example, a 3-axis sensor) capable of detecting H _x , _Hy and H _z . Next, the estimation unit 24 further obtains the angle ψ from cos ψ, which obtains cos ψ using the above equation (6). At this time, the estimation unit 24 adopts + ψ when H _z is positive, and adopts −ψ when H _z is negative. In this way, the angle ψ is estimated by the estimation unit 24.

When the estimation unit 24 not only estimates the distance (distance r) and the azimuth angle (angle θ) between the generating element 11 and the sensor 21, but also estimates the elevation angle (angle ψ), the generating element 11 It becomes possible to estimate the terminal 20 in three-dimensional coordinates based on the position of.

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 the equation (3) described above, the norm of the magnetic field becomes the minimum value when ωt = π / 2, 3π / 2, and when ωt = 0, π. 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 equations (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, y-axis direction component, and z-axis direction component of the magnetic field at the position (r, 0, ψ) of the sensor 21 have the following equations having diameters in the x-axis and z-axis directions. (10), it can be considered that an elliptical body having a diameter of _H'T in the y-axis direction is rotated by ψ with the y-axis as the rotation axis.

Further, when θ ≠ 0, it is advisable to perform conversion as in the following equations (11-1) and (11-2).

Substituting the above equations (11-1) and (11-2) into the above equation (9) gives the following equation (12).

The above equation (12) is a general equation 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 with respect to the position of the generation element 11, the field F detected by the sensor 21 and the generation element 11 received by the receiving unit 22 at the terminal 20 are estimated. The distance and angle between the generating element 11 and the sensor 21 are estimated based on the rotation information about the rotation of. By using the rotational motion of the generating element 11 in this way, for example, by installing only one generating element 11, the position of the terminal 20 determined by the distance L and the angle α from the generator 10 is estimated in the environment. be able to. Therefore, the infrastructure installation cost can be reduced as compared with the method of installing many transmitters in the environment such as the fingerprint method.

The rotation information regarding the rotation of the generating element 11 includes the time and the rotation angle ωt of the generating element 11, and the estimation unit 24 receives the size and detection time of the field F detected by the sensor 21 and the receiving unit 22. The distance and angle between the generating 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 generating element 11 as rotation information from the transmitting unit 14 of the generation device 10 to the receiving unit 22 of the terminal 20.

The generating 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 of utilizing the rotation of the electromagnetic field generation source or the ultrasonic wave generation source.

The electromagnetic field generation source may be a magnet that generates a magnetic field, or an antenna or a laser that radiates an electromagnetic wave. When the electromagnetic field generation source is a magnet, the electromagnetic field generation source itself can have a simple configuration. Further, when an antenna or a laser is used, an error may occur in the estimated distance due to the influence of reflection and absorption of electromagnetic waves, but in the case of a magnet, there is no such influence. It is possible to reduce the error in the estimation accuracy of the distance between the sensor 21 and the sensor 21, and by extension, the estimation accuracy of the position of the terminal 20. When the electromagnetic wave source is an antenna or a laser, 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 device.

When the generating element 11 is a 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, so that the generating element 11 can be estimated. The terminal 20 with three-dimensional coordinates based on the position of 11 can also be estimated.

In the above 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 rotation speed in which the estimation unit 24 is included in the rotation information in the terminal 20. We have described an example of making the above estimation using the above. However, the rotation information does not have to 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 estimation using the set rotation speed. be able to.

Finally, with reference to FIG. 16, an example of the hardware configuration of the terminal 20 of the present invention will be described. 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 (component) 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. That is, each functional block may be realized by one physically and / or logically coupled device, or two physically and / or logically separated physical and / or logically linked to each other by wire and / or wirelessly. It may be realized by the above-mentioned apparatus.

In the following description, the word "device" 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 more of the devices shown in the figure, or may be configured not to include some of the devices.

For each function in the terminal 20, by loading predetermined software (program) on hardware such as the processor 20A and the memory 20B, the processor 20A performs an calculation, communication by the communication module 20D, and data in the memory 20B and the storage 20C. It is realized by controlling the reading and / or writing of.

Although the present embodiment has been described in detail above, it is clear to those skilled in the art that the present embodiment is not limited to the embodiments described in the present specification. This embodiment can be implemented as an amendment or modification without departing from the spirit and scope of the present invention as determined by the description of the scope of claims. Therefore, the description herein is for purposes of illustration only and has no limiting implications for this embodiment.

The terms described herein and / or the terms necessary for understanding the present specification may be replaced with terms having the same or similar meanings.

The phrase "based on" as used herein does not mean "based on" unless otherwise stated. In other words, the statement "based on" means both "based only" and "at least based on".

As long as "include", "including", and variations thereof are used herein or within the scope of the claims, these terms are similar to the term "comprising". In addition, it is intended to be inclusive. Moreover, the term "or" as used herein or in the claims is intended to be non-exclusive.

In the present specification, a plurality of devices shall be included unless the device has only one device apparently in context or technically.

1 ... position estimation system, 10 ... generator, 11 ... generating element, 12 ... driving unit, 13 ... timer, 14 ... transmitting unit, 20 ... terminal, 21 ... sensor, 22 ... receiving unit, 23 ... timer, 24 ... estimation Department, F ... Field.

Claims (5)

A position estimation system that estimates the position of a terminal, including a generator that generates a field and a terminal.
The generator is
Field generation element and
A drive unit that rotates the field generating element and
A transmission unit that transmits rotation information of the field generation element to the terminal,
Including
The terminal is
A detector that detects the field generated by the field generation element, and
A receiver that receives the rotation information and
In order to estimate the position of the terminal with respect to the position of the generator, the field generating element and the detection are based on the field detected by the detection unit and the rotation information received by the reception unit. The estimation part that estimates the distance and angle between the parts, and the estimation part,
Including
The rotation information includes a time and a rotation angle of the field generating element.
The estimation unit has 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 and
Position estimation system. 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 . The electromagnetic field generation source is a magnet that generates a magnetic field, or an antenna or a laser that radiates an electromagnetic wave.
The position estimation system according to claim 2 . The electromagnetic field generation source is a magnet having an asymmetric strength.
The drive unit rotates a magnet having an asymmetrical strength at a constant speed.
The position estimation system according to claim 3 . The electromagnetic field generation source is a magnet having a symmetric intensity.
The drive unit makes a rotational motion including constant velocity rotation in a plurality of different cycles for the magnet having a symmetric intensity.
The position estimation system according to claim 3 .

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