JP2019203896A - Wireless position sensing using magnetic field of single transmitter - Google Patents

Abstract

To provide a positioning system for determining the location of a receiver relative to a transmitter that provides high accuracy and does not require large databases.SOLUTION: The system includes a transmitting coil 102 having a known orientation with respect to the earth's coordinate system and configured to transmit a periodic signal during a positioning event, at least one receiver 104 including a sensing unit for measuring a magnetic field vector produced by the transmitting coil 102 and an orientation of the receiver 104 with respect to the earth's coordinate system, and at least one computing unit 118 configured to estimate a position and orientation of the receiver 104 with respect to the coordinate system of the transmitting coil 102 using the measured magnetic field vector, the measured orientation with respect to the earth's coordinate system, and the known orientation of the transmitting coil 102 with respect to the earth's coordinate system.SELECTED DRAWING: Figure 1A

Description

  The present application relates to wireless detection of the position of a device such as a portable or mobile device.

  There is an increasing demand for methods for determining the position of mobile or portable objects or devices such as mobile phones or blood-borne sensors. GPS, LORAN and similar systems can provide location information, but often have a resolution on the order of 15 meters. Also, such systems are more difficult to use indoors due to changes in signal propagation through building walls and other configurations. WIFI or BLUETOOTH (registered trademark) triangulation has been proposed, but there may be only a low accuracy of 1-2 m indoors. However, such schemes often require a large database for known transmitters (TX). Accordingly, there is a need for a positioning system that has high accuracy and does not require a large-scale database.

  US 2013/0166002 by Jung et al., Published on June 27, 2013, is cited and its disclosure is incorporated herein.

  Where possible, the above and other objects, features and advantages of the present invention will become more apparent when read in conjunction with the following description and drawings, wherein like reference numerals are used to refer to like features that are common to the drawings. become.

1 is a simple block diagram of a positioning system according to one embodiment. FIG.

1B is a block diagram illustrating the system of FIG. 1A in a three-dimensional environment. FIG.

It is a simple block diagram of the positioning process by one Embodiment.

It is the figure which showed the experimental setting example of the system of FIG. 1A.

It is a flowchart which shows the positioning process by one Embodiment.

FIG. 2 is a simple block diagram of a positioning system incorporated in a computing unit with which a receiver is associated.

It is a human body wearing example of the system of FIG.

It is a building area application example of the system of FIG.

It is a simple block diagram of the positioning system incorporated in the arithmetic unit associated with the transmission coil.

It is a human body wearing example of the system of FIG.

FIG. 9 is an embodiment of the system of FIG. 8 in which a receiver is incorporated into the controller.

FIG. 9 is an embodiment of the system of FIG. 8 in which the computing unit is separated from the receiver and the transmit coil.

1 is a simple block diagram of a positioning system according to an embodiment in which a transmission coil and a receiver are separated from a computing device and have another computing device.

It is a human body wearing example of the system of FIG.

It is a building area application example of the system of FIG.

FIG. 13 is an embodiment of the system of FIG. 12 where the pen-shaped controller has a receiver.

13 is an embodiment of the system of FIG. 12 in which the pen-shaped controller has a receiver and the computing unit is separated from the electronic display device.

4 illustrates quadrant determination processing according to one embodiment.

An example beacon signal configuration utilizing time division according to one embodiment is shown.

An example beacon signal configuration utilizing modulation according to one embodiment is shown.

A collision avoidance configuration according to one embodiment is shown.

A transmit coil design according to one embodiment is shown.

A transmit coil design incorporating an LC resonator according to one embodiment is shown.

A transmit coil design incorporating an excitation coil according to one embodiment is shown.

  The accompanying drawings are for illustrative purposes and are not necessarily to scale.

  In the following description, a mode in the case of being generally implemented as a software program is described. One skilled in the art will readily appreciate that such software equivalents can also be built in hardware, firmware or microcode. Since data manipulation algorithms and systems are well known, this specification specifically forms part of the systems and methods described herein, or algorithms and systems that cooperate more directly with said systems and methods. It is about. Although not specifically illustrated or described herein, other aspects of such algorithms and systems, as well as hardware or software, that generate or process signals associated therewith, are as such known in the art. Selected from various systems, algorithms, components and elements. Given the systems and methods described herein, software that is not specifically illustrated, suggested, or described herein, but that is useful in the implementation of any aspect, is prior art and is commonly used in the art. It is within the scope of knowledge.

  Each aspect here has the advantage of enabling quick position determination using a low power microcontroller. A large database of hot spots or antennas is not required. Each aspect enables ultrafast motion tracking.

  Throughout this disclosure, the term “coil” as used when referring to an antenna is not limiting and other types of antennas capable of performing the listed functions can be used. In each aspect here, low frequencies are used, for example <1 MHz or <500 kHz, ~ 70 kHz or ~ 80 kHz or ~ 35 kHz. Other frequencies can be used, for example> 1 MHz. The magnetic sensors described herein can include sensors that include two or more substantially orthogonal coils that measure magnetic field components. Triaxial or other magnetoresistive sensors can also be used in combination or alternatively.

  Throughout this disclosure, reference to the earth's coordinate system includes other reference coordinate systems that are common or substantially common to the transmitter and receiver.

  In one embodiment, the earth coordinate orientation is used, rotating the measured magnetic field from uvw coordinates to xyz coordinates, then examining the strength and direction of the magnetic field, and where (at what position) in the transmitter near field. It is determined whether or not the intensity and direction are generated. This determination position is substantially equal to the position of the receiver (RX).

  In view of the above, in each aspect, the position of the receiver in the vicinity of the wireless transmitter is determined. There is a technical effect of detecting the magnetic field from the transmitter and determining the position of the receiver using the detected magnetic field. Further technical effects of each aspect include displaying the receiver position indication on an electronic display device and transmitting the determined position to a transmitter, computer or computing unit or other device.

  FIG. 1A is a basic block diagram of a positioning system 100 according to an embodiment. As shown, the positioning system 100 includes a transmitter (shown as an antenna coil 102) and at least one receiver 104. The receiver 104 includes a three-axis magnetic sensor 106 and an orientation sensor 108. The coil 102 can be a two-dimensional or three-dimensional circle, ellipse, rectangle, quadrangle, rhombus, triangle, or the like. By including the signal generator 110 and the driver 112, a waveform may be generated, the coil 102 may be driven, and a periodic beacon signal having a constant frequency may be transmitted. Any periodic signal can be used, but the most effective sinusoidal signal is preferred to simplify transmitter and receiver design. The transmission coil 102 generates a spatial magnetic field in which the strength and direction of the magnetic field depend on the position in space. As shown, amplifier 112 and A / D converter 116 may be operatively connected to amplify and convert the output of magnetic sensor 106 into a digital format suitable for the input of computing unit 118. The arithmetic unit 118 may further receive the output of the direction sensor 108.

FIG. 1B shows the operation of the system 110 in a three-dimensional environment. Also shown in FIG. 2 are the steps involved in determining the position and orientation of the receiver 104 relative to the coil 102. The three-axis magnetic sensor 106 of the receiver 104 uses the magnetic field (H _u , H _v , H _w ) generated by the transmitter coil 102 at the position (x, y, z) of the receiver 104 in the coordinate system (U , V, W) (block 202). The three-dimensional orientation sensor 108 measures the orientation in the earth coordinate system (α _Earth , β _Earth , γ _Earth ) (block 204). The measurement data (H _u , H _v , H _w ) and (α _Earth , β _Earth , γ _Earth ) are provided to the arithmetic unit 118. The computing unit 118 may be located at the receiver, transmitter, or other location. When the arithmetic unit 118 is not arranged in the receiver 104, the measurement data may be transmitted to a remote arithmetic unit arranged outside the receiver 104 via a wireless line or a wired line. The orientation of the transmit coil 102 in the Earth coordinate system (α _{Tx, Earth} , β _{Tx, Earth} , γ _{Tx, Earth} ) is provided to the arithmetic unit 118 (block 206). The direction of the transmission coil 102 in the earth coordinate system (α _{Tx, Earth} , β _{Tx, Earth} , γ _{Tx, Earth} ) can be provided to the remote calculation unit via a wireless line or a wired line. If the coil is fixedly installed, a known value of the direction of the transmission coil 102 in the earth coordinate system (α _{Tx, Earth} , β _{Tx, Earth} , γ _{Tx, Earth} ) can be stored in the arithmetic unit 118. The stored value can be used in subsequent calculations.

The arithmetic unit 118 calculates the direction of the receiver 104 with respect to the transmission coil 102 from the direction sensor data (α _Earth , β _Earth , γ _Earth ) and known coil orientation data (α _{Tx, Earth} , β _{Tx, Earth} , γ _{Tx, Earth} ). Estimate (α _x , β _y , γ _z ) (block 208). Then, using the estimated azimuth (α _x , β _y , γ _z ) with respect to the transmission coil, the measured magnetic field vectors (H _u , H _v , H _w ) are adjusted to match the coordinate system (X, Y, Z) of the transmission coil. Can be rotated (block 210). By this processing, magnetic field vectors (H _x , H _y , H _z ) at the receiver position (x, y, z) generated by the transmission coil in the coordinate system (X, Y, Z) of the transmission coil are obtained. It is done. Since an expected magnetic field vector (H _x , H _y , H _z ) at an arbitrary position (x, y, z) generated by the transmission coil by physical modeling can be estimated, the estimated magnetic field vector (H _x , H _y , H _z ) may be utilized to estimate the receiver position (x, y, z) (block 212). The orientation and position of the receiver 104 relative to the transmit coil 102 is then output by the arithmetic unit 118 (block 214).

  The aspect of indoor RF transmission can be highly dependent on line characteristics, eg, building structure. In each embodiment, for example, frequencies below 1 MHz are used to effectively propagate through walls, human bodies, and other indoor environment configurations. Since such frequencies have a wavelength of several tens of meters, the receiver can operate in the near field rather than the far field of the transmitting antenna. Thus, it is not necessary to consider or compensate for radioactive effects in each embodiment. If the frequency is lowered, the antenna becomes larger and the object passing rate is improved. In each embodiment using a frequency of 12 MHz or higher, the influence of the wall on the position accuracy is greater than in the case of a low frequency. However, a frequency of 12 MHz or more can be used, and it does not change that the human body is advantageously passed.

  Because the frequency of use of the electromagnetic spectrum is low at low frequencies, various low frequencies can be used in the disclosed embodiments. Other users include amateur radio operators. Multiple frequencies can be used for different transmitters, and the receiver can avoid interference by providing a notch filter corresponding to a particular transmitter frequency.

  Various azimuth sensors 108, for example, a solid azimuth meter and an accelerometer device can be used. The earth orientation is used as a reference for rotation from xyz to uvw. The triaxial magnetic sensor can be used to detect both the geomagnetic field (DC field) and the TX magnetic field (AC field), or another sensor can be used.

  Throughout this disclosure, once the position or orientation of the receiver relative to the transmitter is determined, the position or orientation may be another coordinate system, such as an earth-relative system such as WGS84, or a room or building coordinate system. Can be transformed into a local system. Coordinate transformations can be performed by rotation, skew, and other well known techniques in the field of computer graphics and cartography.

  FIG. 3 illustrates an embodiment of a system 100 that uses a transmitter coil 102 to detect the position and orientation of a receiver 104. In the example of FIG. 3, 750 kHz is used as the transmission signal frequency, and 28 coils, a coil diameter of 22 cm, and a peak-to-peak signal amplitude of 10 V are used as the coil 102. In this example, the receiver 104 may be tracked by estimating the spatial magnetic field distribution generated by the transmitter coil 102 by using a magnetic field distribution model. The reason why the magnetic field distribution model is used instead of the magnetic field model based on the mathematical formula is that the model based on the mathematical formula tends to show an inaccurate magnetic field particularly near the transmission coil. By using this distribution model, tracking accuracy is greatly improved. The method used to apply the distribution model will be described later. First, each of the turns of the coil 102 is divided into a plurality of parts (in this example, 30 segments are used), and the resultant magnetic field vector at the observation point is obtained by adding the magnetic field vectors generated by the 30 segments. The same is repeated for all the turns of the coil 102. Alternatively, instead of performing the process of dividing each turn of the coil 102 into segments and applying the Bio-Savart law to all segments of each turn, the magnetic field by one turn is calculated and the number of turns of the coil 102 is By multiplying, the total magnetic field can be obtained. Here, it is assumed that the coil wire is extremely fine.

A solid compass / accelerometer is used as the orientation sensor 108 of the receiver 104 to measure the orientation (α _Earth , β _Earth , γ _Earth ) of the receiver 104 in the earth coordinate system. In this example, the output rate of the azimuth sensor 108 is 220 Hz, the geomagnetic field resolution is 5 milligauss, and the linear acceleration sensitivity is 4 mg / digit. A method for obtaining the orientation (α _Earth , β _Earth , γ _Earth ) of the receiver using the measurement output of the solid compass and the accelerometer will be described below. The triaxial accelerometer provides the receiver pitch and roll angles, while the compass provides the receiver yaw and uses the following formula:
However,
A _x is + x direction of the acceleration _{A y} + y direction of the acceleration _{A z} + z-direction acceleration _{M x} + field _{M y} in the x direction + y direction of the magnetic _{field, M z} and + z direction of the magnetic field.

  The azimuth sensor 108 in this example defines a ground reference system that is used in many aerospace applications by using north, east, and down (commonly referred to as NED) angle transformations. The arithmetic unit 118 receives data from the orientation sensor and calculates the orientation of the receiver 104 with respect to the earth by applying the above formula. In this example, instead of the classic Euler angles, (yaw, pitch, roll) angle transformations are used and the mutual transformation is easy.

Next, using the known orientation (α _{Tx, Earth} , β _{Tx, Earth} , γ _{Tx, Earth} ) of the transmitter coil 102 in the Earth coordinate system, the orientation (α _Earth , β _Earth , γ _Earth ) is converted into the orientation (α _x , β _y , γ _z ) of the receiver 104 in the coordinate system (X, Y, Z) of the transmitter coil 102. In this example, the transmitter coil is upright. For this reason, it is certain that β _{Tx, Earth} = 0 and γ _{Tx, Earth} = 0, which is as follows.

If β _{Tx, Earth} ≠ 0 or γ _{Tx, Earth} ≠ 0, a coordinate transformation can be used to determine the correct angle.

In the illustrated embodiment, a triaxial coil comprising three planar coils arranged orthogonally is used as a magnetic field sensor 106 that measures the magnetic field vector generated by the transmit coil 102. A solid triaxial magnetic sensor (eg, Honeywell HMC1043) can also be used. The three-axis magnetic sensor 106 of the receiver 104 measures the magnetic field vector (H _u , H _v , H _w ) at the position of the receiver 104 in the coordinate system (U, V, W) of the sensor 106 (receiver) itself. . The magnetic field vectors (H _u , H _v , H _w ) measured in the coordinate system (U, V, W) of the receiver 104 itself are the receiver 104 in the coordinate system (X, Y, Z) of the transmitter coil 102. Are converted into magnetic field vectors (H _x , H _y , H _z ) in the transmitter coordinate system (X, Y, Z) using the azimuth (α _x , β _y , γ _z ). This is as follows.

Next, the estimated magnetic field vectors (H _x , H _y , H _z ) are analyzed using a transmitter magnetic field model to estimate the position of the receiver. FIG. 4 shows a flowchart 400 for estimating the position of the receiver 104 relative to the coil 102. First, the orientation (yaw, pitch, and roll) of the receiver is read from the orientation sensor 108, and the amplitude of the magnetic field is read from the triaxial magnetic sensor 106 (step 402). In step 404, the arithmetic unit applies angle correction to the magnetic field vectors read from the three coils of the magnetic sensor 106 (using the rotation matrix generated from the orientation sensor 108 data), and the receiver 104 for the coil 102. Are determined and output (step 406).

In step 408, the arithmetic unit 118 determines an approximate value of the initial position of the receiver 104 using the angle / orientation corrected in step 404. The transmitter coil is a point signal source, as described in Wing Phi et al., “Magnetic Tracking System for Radiation Therapy”, IEEE Tran. Biomedical Circuits and system 2010, the entire contents of which are incorporated herein by reference. The approximate position may be calculated by assuming a field equation.

These near field equations can be written in Cartesian coordinates as follows:

Solving the above equation gives the following.
(14)
Where K is a proportionality constant calculated empirically (for a given transmitter and receiver).
Substituting these into the above equation and calculating again gives the following.
As a result, the estimated position x, y, z of the receiver is obtained.

  Moving to step 410, the measured magnetic field data is compared with the magnetic field distribution model for the transmitting coil 102 described above to determine an error. If the error is within a predetermined limit, proceed to step 416 and compare the x / y / z step size with a predetermined lower limit. If the step size is the lower limit value, the arithmetic unit 118 outputs the estimated x, y, z position of the receiver 104 (step 420). If not, reduce the step size, eg, halve (step 418), and re-evaluate the error (step 410). If it is determined in step 410 that the error is not within the predetermined limit, the process proceeds to step 412. In step 412, predicted magnetic field values are obtained for a plurality of positions around the estimated position. As an example, 27 corners are evaluated (x−Δx: Δx: x + Δx, y−Δy: Δy: y + Δy, z−Δz: Δz: z + Δz), where Δ is the step size. Thereafter, the Euclidean distance between the predicted magnetic field value and the predicted magnetic field value calculated for the 27 corners is obtained. The shortest corner (out of 27) is selected as the new starting position (step 414) and this step is repeated until the solution converges and the error falls within the predetermined limits. In the illustrated example, in most of the target area, an orientation error of 1 degree or less and a position error of several millimeters or less were observed. The accuracy is further improved by optimizing the design of the transmission coil 102 (size, shape, transmission power, etc.) and the design of the receiver 104 (amplification sensitivity, noise characteristics, etc.).

  The positioning system 100 may be incorporated into various arithmetic systems and networks having different configurations. In FIG. 5, an implementation in which the receiver 104 is associated with a computing device 118 such as a television receiver, mobile phone, tablet computer, notebook computer, wearable computing device, game device, video streaming set-top box, etc. The form is shown. In this embodiment, the computing device executes an application 121 that uses position / orientation data. The receiver 104 may be disposed in / on / above / below / above / in the computing device 118. Receiver 104 may optionally be part of computing device 118. Using the receiver 104, the computing device 118 can estimate its position and orientation. The computing device 118 may use the estimated position and orientation data in its own application, or can share data with other computing devices 119 via a wired or wireless line.

  FIG. 6 shows still another embodiment. In this embodiment, the transmission coil 102 is attached to a human body using a belt, clothes, glasses, or the like, and the tracking receiver 104 is incorporated in the wearable arithmetic unit. ing.

  FIG. 7 shows still another embodiment. In this embodiment, the transmission coil 102 is installed in a building 140 (wall, roof, ceiling, floor, etc.), and the tracking receiver 104 is a mobile computing device. Built in.

  In still other embodiments, the transmit coil 102 is integrated with the computing device 118 or is operably connected. In this embodiment, as shown in FIG. 8, receiver 104 (including magnetic sensor 106 and orientation sensor 108) measures the magnetic field strength in its own coordinate system and measures its orientation in the Earth coordinate system. When there is an arithmetic unit in the receiver 104, the position and orientation can be estimated using the measurement data as described above. The receiver 104 can send measurement data or position and orientation estimation data to the arithmetic device 118 or other arithmetic device 119 associated with the transmission coil via a wired or wireless line.

  In the embodiment of FIG. 8, the receiver 104 has the raw measurement data or processed necessary to estimate the position and orientation of the receiver 104 relative to the arithmetic unit 118 or other arithmetic unit 119 associated with the transmit coil 102. You can send data. This configuration is particularly useful when the transmission coil 102 is not stationary (that is, a moving body). When the transmission coil 102 is a moving body, if the receiver 104 needs to estimate its position and orientation internally, it is necessary to send the orientation data of the transmission coil 102 in the earth coordinate system to the receiver 104 in real time. If the receiver 104 does not need to estimate its position and orientation internally, the raw measurement data or processed data can be sent to the computing device 118, which, as described above, can receive the receiver 104. Can be estimated.

  FIG. 9 shows still another embodiment similar to the embodiment of FIG. 8, in which the transmitting coil 102 and the computing device 118 are mobile wearable computing devices (e.g., the user's head). The tracking receiver 104 (including the magnetic sensor 106 and the orientation sensor 108) is placed on the wrist, arm, finger, or the like. A pen-shaped tracking receiver that can be controlled by hand may be used as well. In any of the disclosed embodiments, two or more receivers 104 can operate simultaneously and independently, and the same beacon signal from the transmit coil 102 can be used to detect their position and orientation.

  FIG. 10 shows another embodiment similar to the embodiment of FIG. 8, in which the computing device 118 realized as a tablet computer, a smartphone, a notebook computer, or a smart TV is Measurement data or position / orientation estimation data is received from a controller 123 (for example, a game remote controller or a TV remote controller) incorporating the receiver 104. The controller 123 operably communicates with the computing device 118 using the illustrated wired or wireless line such as Bluetooth (registered trademark) or infrared. In some embodiments, the rectangular transmission coil 102 may be formed around the computing device 118 (eg, generally near the periphery of the television).

  FIG. 11 shows still another embodiment similar to FIG. 8, in which the computing device 118 receives measurement data or position / orientation estimation data from a controller 123 that includes a receiver 104. Implemented as a smartphone (or tablet). Again, the arithmetic unit 118 executes the application 121 that uses the data received from the controller 123. The computing device 118 sends the video to another device 130 (for example, a television or a video monitor) having video display capability (via a wired or wireless line).

  FIG. 12 shows yet another embodiment in which the transmit coil 102 and receiver 104 operate as stand-alone components rather than as part of a computing device. The receiver 104 (including the magnetic sensor 106 and the orientation sensor 108) measures the magnetic field at that position in its own coordinate system and measures its orientation in the earth coordinate system. When the receiver 104 has a built-in arithmetic unit, its position and orientation can be estimated in the transmitter coordinate system by the method described above. The measurement data or the estimation data of the position and orientation is sent to one arithmetic device 118 (for example, a television, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a wearable device, a game device via a wired or wireless line. , Video streaming box, etc.) or a plurality of arithmetic devices (for example, arithmetic device 119). In this embodiment, it is assumed that the orientation of the transmit coil 102 in the earth coordinate system is known to the computing system, and the receiver is responsible for the raw measurement data or processed data required to estimate the position and orientation of the receiver 104. By simply sending data to the computing device (118 or 119), the computing device can estimate the position and orientation of the receiver 104.

  FIG. 13 shows an embodiment similar to FIG. 12, in which the transmitter coil 102 is attached to the human body using a belt, clothes, glasses, etc., and the tracking receiver 104 is connected to the wrist, Arranged on arms, fingers, etc. A pen-shaped tracking receiver 104 that can be controlled by hand may be used similarly.

  FIG. 14 shows still another embodiment similar to FIG. 12, in which the transmission coil 102 is fixedly installed in a building 140 (wall, roof, ceiling, floor, etc.) The mobile tracking receiver 104 can estimate the position and orientation using the beacon signal transmitted by the coil 102, and can send the estimated data of the position and orientation to the computing device 118 via a wired or wireless network.

  FIG. 15 shows still another embodiment similar to FIG. 12, in which a pen-shaped controller 123 including a receiver 104 is connected via a Bluetooth (registered trademark) or Wi-Fi line. Then, the measurement data or the position / orientation estimation data is sent to the arithmetic device 118 (TV, mobile phone, tablet, notebook, desktop, etc.). The arithmetic device 118 executes an application 121 that uses data received from the controller 123.

  FIG. 16 shows still another embodiment similar to FIG. 12, in which a pen-shaped controller 123 including a receiver 104 is connected via a Bluetooth (registered trademark) or Wi-Fi line. Then, the measurement data or the estimated position / orientation data is sent to the arithmetic device 118 (mobile phone, tablet, notebook, desktop, etc.). The arithmetic device 118 executes an application 121 that uses data received from the controller 123. The computing device 118 sends video and / or audio (via a wired or wireless line) to the video display device 142 (eg, television, monitor, projector, etc.).

FIG. 17 shows a processing step 1700 for determining a quadrant based on the phase. That is, processing step 1700 allows system 100 to determine one of four candidate quadrants in the XY plane of the XYZ coordinate system where the receiver is located. Assuming that the transmitter coil 102 is in the XY plane of the transmitter coordinate system (X, Y and Z coordinate systems), the quadrant is obtained by the relative phase between the signals received by the coils of the triaxial sensor 106. In the most practical application, the receiver 104 is located in the + Z direction (on one side of the transmitter 102), so a quadrant detection method in such a setting will now be described. This method may be extended to an eight quadrant system to locate a device located in any direction of the transmitter 102. Processing step 1700 begins at step 1702 where a magnetic field signal is detected by magnetic sensor 106, and the relative phase is stored (step 1704). In the illustrated example, the signal H _u -H _w is out of phase in the implementation block 1702 and the signal H _u -H _w is also out of phase. In step 1706, four candidate locations (one in each xy quadrant) are determined by transforming the signal from the earth's U, V, W coordinate system to the transmitter's X, Y, Z coordinate system. Once the four candidate positions are known, the expected relative phase between the signals at the candidate receiver position is calculated (also step 1706) and compared to the observed relative phase (step 1708). This relative phase matches exactly so that the exact quadrant of the receiver is known and the exact position of the receiver is known (output at step 1710). In the example shown in FIG. 17, the pair of H _u -H _w and H _v -H _w is in a phase-shifted relationship only in quadrant 3, so the receiver is actually in quadrant 3.

  As an alternative to the initial receiver position approximation method described above with respect to step 408 of FIG. 4, an approximation of the initial position of the receiver 104 may be performed using an available transmitter magnetic field distribution model. Magnetic field vectors at various positions around the transmitter 102 (apart from a certain rough space) are calculated in advance and stored in a table. This lookup table can be used to map the location of the receiver 104 directly into the transmitter coordinate system. Alternatively, this table may be used to perform a curve approximation and generate a polynomial (similar to step 408 in FIG. 4) used to calculate the approximate position of the receiver 104. The coefficients of the polynomial are specific to a particular transmitter 102 and cannot be generalized for another transmitter. If the approximate position coordinates of the receiver are known by using any of the above-described methods (or a combination of these methods), the position of the receiver 104 is accurately calculated using the distribution model of the transmitter 102. This technique is useful for shortening calculation time and improving accuracy.

  In some embodiments, the beacon signal transmitted by the transmit coil 102 includes a periodic signal used by the receiver 104 to estimate position and orientation. In still other embodiments, the beacon signal may include another signal that provides other information to the receiver 104. Other information that can be transmitted by the transmission coil 102 includes a transmission coil identification number, a transmission coil orientation, a transmission coil position, a transmission signal frequency, the size and shape of the transmission coil, and the like. As illustrated in FIG. 18, another signal including other information can be transmitted in a time division manner. As shown, the first portion 150 of the beacon signal 152 is a positioning signal, and the second portion 154 is an auxiliary signal containing other information. Alternatively, as shown in FIG. 19, the auxiliary signal (156) is transmitted with the periodic signal (158) by the modulator 160 using phase modulation or frequency modulation.

  When multiple systems 100 (ie, multiple sets of transmitters / receivers) are operating in the same vicinity, a particular receiver 104 may pick up transmission signals from multiple transmitters and thereby receive The position of the aircraft cannot be estimated properly. In some embodiments, different transmitter coils 102 transmit at different frequencies. Then, as shown in FIG. 20, each receiver 104 is tuned to a specific frequency of the corresponding target transmitter 102 using a narrowband circuit or filtering. In FIG. 20, since the receiver 2 uses a narrow band circuit tuned to f1, the beacon signal transmitted by the transmission coil 1 is picked up. As a result, the receiver 2 estimates its position and orientation in the coordinate system of the transmission coil 1.

  In some embodiments, the antenna coil 102 may be optimized to improve quality. In one embodiment, a simple coil as shown in FIG. 21 (A) is used. By using the LC resonator 162 configured as shown in FIG. 21B, the quality of the transmission signal can be improved. As shown in FIG. 21C, the quality of the transmission signal can be further improved by using the excitation coil 164 that drives the transmission coil 102. The capacitor 163 shown in FIGS. 21B and 21C may be a voltage-controlled or mechanically-controlled variable capacitor. By using the variable capacitor, the resonance frequency of the LC tank 162 can be adjusted to match the frequency of the transmission signal. In the example shown in FIG. 21, a single end driver is used. Instead of using a single-ended driver, a differential driver may optionally be used.

  Either the arithmetic unit 118 or 119, the receiver 104, the magnetic sensor 106, the azimuth sensor 108, the signal generator 110, the driver 112 and the controller 123 include one or more arithmetic processors, memory, and data analysis and Other data storage devices for performing analysis described herein, and related parts may be included. Each processor includes one or more microprocessors, microcontrollers, field programmable gate arrays (FPGA), application specific integrated circuits (ASIC), programmable logic devices (PLD), programmable logic arrays (PLA), programmable array logic. A device (PAL) or digital signal processor (DSP) can be included. The data storage unit includes one or more information storage memories accessible to the processor, or is communicably connected to the information storage memory. The memory may be in a housing, for example, or may be part of a distributed system. The expression “processor accessible memory” includes all data storage devices that the processor 186 can send or receive data to, such as volatile or non-volatile memory, removable or fixed memory, electronic memory , Magnetic memory, optical memory, chemical memory, mechanical memory or other memory. Examples of processor accessible memory include registers, floppy disks, hard disks, tapes, barcodes, compact disks, DVDs, read only memories (ROM), erasable programmable read only memories (EPROM, EEPROM or Flash) And random access memory (RAM). One of the processor-accessible memories in data storage system 140 is a tangible, non-transitory computer-readable storage medium, i.e., a non-transitory involved in storing instructions for execution provided to the processor There can be a mechanical device or product.

  Each aspect described here may be embodied as a system or method. Accordingly, each aspect described herein may take the form of all hardware, all software (including firmware, resident software, microcode, etc.), or a combination of software and hardware aspects. . All of these aspects may be generically referred to herein as “services”, “circuits”, “circuit configurations”, “modules”, or “systems”.

  Also, each aspect described herein may be embodied as a computer program product, including computer readable program code stored on a tangible non-transitory computer readable medium. Such a medium can be produced, for example, by pressing a CD-ROM as is conventional in the product. The program code includes computer program instructions that are readable by the processor (and possibly by other processors) and contribute to the functions, operations or operational steps of each aspect described herein that are executed by the processor. . The computer program code for executing the operation of each aspect described herein may be described in any combination of one or two or more program languages.

  The present invention includes combinations of the embodiments described herein. References such as “specific aspects” or “embodiments” refer to configurations that are present in at least one aspect of the invention. Different references such as “an aspect” (or “embodiment”) or “a plurality of specific aspects” do not necessarily refer to the same aspect or aspects, These aspects are not mutually exclusive unless it is obvious that it is one of knowledge in the technical field. The use of the singular or plural form when referring to “a method” or “a plurality of methods” is not limiting. Unless otherwise expressly stated, the term “or” is used in this disclosure in a non-exclusive sense.

Although the invention has been described in detail with particular reference to certain preferred embodiments, it will be understood that variations, combinations and modifications can be made by those skilled in the art within the spirit and scope of the invention.
In addition, the positioning system and method by this invention are comprised as follows, for example.
[1]
a) a transmission coil having a known orientation in the earth coordinate system and transmitting a periodic signal during a positioning event;
b) at least one receiver having a detection unit for measuring the magnetic field vector generated by the transmitter coil and the orientation of the receiver in the earth coordinate system;
c) using the measured magnetic field vector, the measured orientation in the earth coordinate system, and the known orientation of the transmitter coil in the earth coordinate system, the position of the receiver in the transmitter coordinate system, and A positioning system comprising at least one computing unit configured to estimate a bearing.
[2]
The positioning system according to [1], wherein the detection unit includes a three-axis magnetic sensor that measures a magnetic field and an orientation sensor that measures an orientation.
[3]
The transmission coil is incorporated in a mobile electronic device, and both the transmission coil and the position sensor move simultaneously, and the orientation of the transmission coil in the earth coordinate system is supplied in real time to the arithmetic unit in the receiver. The positioning system according to [1] above.
[4]
The positioning system according to the above [1], comprising a plurality of receivers operating independently at the same time.
[5]
The positioning system according to [1], wherein the arithmetic unit is incorporated in the receiver.
[6]
The arithmetic unit is separated from the receiver, and the receiver transmits the measured magnetic field vector and the azimuth in the earth coordinate system to the arithmetic unit via a wired or wireless line. ] The positioning system described in the above.
[7]
The positioning system according to [1], wherein the magnetic sensor includes three planar coils whose directions are orthogonal to each other.
[8]
The positioning system according to [1], wherein the receiver includes a plurality of three-axis magnetic sensors that measure the magnetic field of the transmission coil.
[9]
The positioning system according to [1], wherein the transmission coil is incorporated in the arithmetic unit, and position data of the receiver is transmitted to the arithmetic unit.
[10]
The positioning system according to [1], wherein the arithmetic unit includes at least one of a television receiver, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a wearable device, and a video game device.
[11]
The positioning system according to [1], wherein the receiver is incorporated in the arithmetic unit, and the position of the arithmetic unit with respect to the transmission coil can be determined.
[12]
The positioning system according to [1], wherein the receiver is configured as a stand-alone unit, and the receiver transmits position and orientation data to the arithmetic unit via a wired or wireless line.
[13]
The positioning system according to [1], wherein the transmission coil is configured to transmit a beacon signal, and the beacon signal includes a periodic signal unit for determining a position of the receiver and an auxiliary signal unit. .
[14]
The positioning system according to [13], wherein the auxiliary signal unit includes at least one of coil identification information, coil orientation, transmission signal frequency, transmission coil size, and transmission coil shape.
[15]
A plurality of transmit coils each configured to transmit at a different frequency;
The positioning system according to [1], further including a plurality of receivers each receiving a signal from one of the transmission coils.
[16]
The positioning system according to [1], wherein the arithmetic unit is configured to determine a quadrant of the receiver position relative to the coil using phase-based quadrant detection.
[17]
The positioning system according to [1], wherein the arithmetic unit performs initial estimation of the receiver position and the azimuth of the receiver, and then evaluates a plurality of positions around the initially estimated position.
[18]
The positioning system according to [17], wherein the arithmetic unit further evaluates an error between the field value measured for the plurality of positions and the estimated field value.
[19]
The arithmetic unit is further configured to select a second estimated position from the plurality of positions, and the second estimated position has the smallest field error compared to the other plurality of positions [18]. The positioning system described in.
[20]
Send a periodic signal during a positioning event using the transmit coil,
Using a receiver to detect the magnetic field vector generated by the transmitter coil and the orientation of the receiver with respect to the earth;
Using the arithmetic unit, the measured magnetic field vector, the measured orientation in the earth coordinate system and the known orientation of the transmitter coil in the earth coordinate system, the position and orientation of the receiver in the transmitter coordinate system A method of determining a position of a receiver with respect to a transmission coil.

Claims (15)

a) a transmission coil having a known orientation in the earth coordinate system and transmitting a periodic signal during a positioning event;
b) at least one receiver having a detection unit for measuring the magnetic field vector generated by the transmitter coil and the orientation of the receiver in the earth coordinate system;
c) using the measured magnetic field vector, the measured orientation in the earth coordinate system, and the known orientation of the transmitter coil in the earth coordinate system, the position of the receiver in the transmitter coordinate system, and A positioning system comprising at least one computing unit configured to estimate a bearing.   The positioning system according to claim 1, wherein the detection unit includes a three-axis magnetic sensor that measures a magnetic field and an orientation sensor that measures an orientation.   The transmission coil is incorporated in a mobile electronic device, and both the transmission coil and the position sensor move simultaneously, and the orientation of the transmission coil in the earth coordinate system is supplied in real time to the arithmetic unit in the receiver. The positioning system according to claim 1.   The positioning system according to claim 1, comprising a plurality of receivers operating independently at the same time.   The positioning system according to claim 1, wherein the arithmetic unit is incorporated in the receiver.   The arithmetic unit is separated from the receiver, and the receiver transmits the measured magnetic field vector and the orientation in the earth coordinate system to the arithmetic unit via a wired or wireless line. The positioning system described in.   The positioning system according to claim 1, wherein the magnetic sensor includes three planar coils whose directions are orthogonal to each other.   The positioning system according to claim 1, wherein the receiver includes a plurality of three-axis magnetic sensors that measure the magnetic field of the transmission coil.   The positioning system according to claim 1, wherein the transmission coil is incorporated in the arithmetic unit, and position data of the receiver is transmitted to the arithmetic unit.   The positioning system according to claim 1, wherein the arithmetic unit includes at least one of a television receiver, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a wearable device, and a video game device.   The positioning system according to claim 1, wherein the receiver is incorporated in the arithmetic unit, and the position of the arithmetic unit with respect to the transmission coil can be determined.   The positioning system according to claim 1, wherein the receiver is configured as a stand-alone unit, and the receiver transmits position and orientation data to the arithmetic unit via a wired or wireless line.   The positioning system according to claim 1, wherein the transmission coil is configured to transmit a beacon signal, and the beacon signal includes a periodic signal unit for determining a position of the receiver and an auxiliary signal unit.   The positioning system according to claim 13, wherein the auxiliary signal unit includes at least one of coil identification information, coil orientation, transmission signal frequency, transmission coil size, and transmission coil shape. A plurality of transmit coils each configured to transmit at a different frequency;
The positioning system according to claim 1, further comprising a plurality of receivers each receiving a signal from one of the transmission coils.