Living body motion measurement device and living body motion measurement system

Abstract

A living body motion measurement device is provided with: one or more magnetic generators disposed at a first site of a living body; one or a plurality of magnetic field sensors which are disposed at a different site from the first site of the living body and which measure the magnetic field generated by each of the magnetic generators using two or more orthogonal measurement axes; and a signal processing unit that calculates the relative position between each of the magnetic generators and each of the magnetic field sensors on the basis of the magnetic fields measured by each of the magnetic field sensors.

Description

Technical Field

[0001] The present invention relates to a biological motion measuring device and a biological motion measuring system. This application claims priority from Japanese Patent Application No. 2022-148197 filed in Japan on September 16, 2022, the contents of which are incorporated herein by reference. Background Art

[0002] Patent Document 1 describes a device for measuring three-dimensional in vivo motion. The device attaches a magnetic generator to one of the upper and lower jaws of a living body, and a magnetic field sensor to the other, to measure the relative three-dimensional motion of one jaw relative to the other. The device described in Patent Document 1 includes multiple magnetic generators and multiple calibration coils that are non-contacting with the multiple magnetic field sensors. There are at least five different combinations of magnetic generators, magnetic field sensors, and calibration coils. The initial position and orientation of each magnetic generator and magnetic field sensor are measured by detecting the calibration magnetic field generated by each calibration coil using the magnetic generator and magnetic field sensor.

[0003] Patent Document 2 describes a device for measuring at least one of the relative position and relative movement of a patient's mandible relative to the upper jaw. The device described in Patent Document 2 includes a transmitter coil positioned adjacent to the patient's head and a mandibular sensor positioned on the mandible. The device determines at least one of the relative position and relative movement of the mandible relative to the upper jaw based on the position determined by the mandibular sensor.

[0004] Prior art literature Patent Literature Patent Document 1: Japanese Patent No. 4551395 Patent Document 2: Japanese Patent Application Publication No. 2019-510553. Summary of the Invention

[0005] Problems to be solved by the invention However, the device described in Patent Document 1 requires at least five different combinations of magnetic generators, magnetic field sensors, and correction coils, leading to increased device size and power consumption. Furthermore, the device described in Patent Document 2 requires a transmitter coil positioned adjacent to the patient's head, making it impractical for daily measurements.

[0006] The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a biological motion measurement device and a biological motion measurement system capable of simply measuring the motion of a part of a biological body.

[0007] Solutions to Problems One embodiment of the present invention is a biological motion measurement device, which comprises: one or more magnetic generators, arranged at a first part of the biological body; and one or more magnetic field sensors, arranged at other parts of the biological body different from the first part, for measuring the magnetic field generated by each magnetic generator using more than two orthogonal measurement axes.

[0008] In one embodiment of the present invention, in the above-mentioned biological motion measuring device, the magnetic generator is a bipolar magnet.

[0009] In one aspect of the present invention, in the above-mentioned biological motion measurement device, the magnetic poles of the magnetic generator are arranged so as to face the movable directions of the first portion and the other portion.

[0010] In one embodiment of the present invention, in the above-mentioned biological motion measuring device, the magnetic flux density of the magnetic generator is 300 millitesla or more.

[0011] In one embodiment of the present invention, in the biological motion measurement device, the magnetic field sensor is formed by a combination of one or more of a Hall sensor, a magnetoresistive effect sensor, and a magnetoresistive impedance sensor.

[0012] In one aspect of the present invention, in the above-mentioned biological motion measurement apparatus, the plurality of magnetic field sensors are arranged at different distances from the one magnetic generator.

[0013] In one embodiment of the present invention, the biological motion measurement device further includes one or more posture sensors, which are arranged at at least one of the first portion and the other portion and measure the orientation of the portion in which they are arranged.

[0014] In one embodiment of the present invention, in the above-mentioned biological motion measurement device, the posture sensor measures three-dimensional orientation.

[0015] In one embodiment of the present invention, in the above-mentioned biological motion measurement device, the posture sensor is formed by a combination of one or more of a gyro sensor, an acceleration sensor, and a geomagnetic sensor.

[0016] In one embodiment of the present invention, the above-mentioned biological motion measuring device further includes: a magnetic generator with opposite polarity to the magnetic generator, which is arranged at the first part; and an additional magnetic field sensor, which is arranged at the other part, and is used to measure the magnetic field generated by the magnetic generator with opposite polarity using more than two orthogonal measurement axes.

[0017] In one embodiment of the present invention, in the above-mentioned biological motion measurement device, the first part is a part that is linked to either the upper jaw or the lower jaw of the biological body, and the other part is a part that is linked to the other jaw of the upper jaw or the lower jaw of the biological body that is different from the first part.

[0018] In one embodiment of the present invention, in the above-mentioned living body motion measurement device, the first part is either the upper jaw or the lower jaw in the oral cavity of the living body, and the other part is the other jaw of the upper jaw or the lower jaw in the oral cavity of the living body that is different from the first part.

[0019] In one aspect of the present invention, in the biological motion measurement device, the first site and the other sites are molars.

[0020] In one embodiment of the present invention, in the above-mentioned biological motion measurement device, the magnetic generator is provided on the mouthpiece attached to the first portion, and the magnetic field sensor is provided on the mouthpiece attached to the other portion.

[0021] In one aspect of the present invention, in the above-mentioned biological motion measurement device, the magnetic generator is arranged so that the magnetic pole faces the direction of the opening.

[0022] In one embodiment of the present invention, in the above-mentioned biological motion measurement device, the magnetic field sensor is disposed at a position where two or more vector components of the magnetic field generated by the magnetic generator change.

[0023] In one embodiment of the present invention, in the above-mentioned biological motion measuring device, a posture sensor is also provided on the mouthguard installed at the other part, and the biological motion measuring device also has a signal processing unit, which measures the movement of the jaw of the biological body with six degrees of freedom based on the magnetic field measured by each magnetic field sensor and the orientation measured by the posture sensor.

[0024] One embodiment of the present invention is a biological motion measurement system, which comprises: one or more magnetic generators, arranged at a first part of the biological body; one or more magnetic field sensors, arranged at other parts of the biological body different from the first part, for measuring the magnetic field generated by each magnetic generator using two or more orthogonal measurement axes; and a signal processing unit, which calculates the relative position between each magnetic generator and each magnetic field sensor based on the magnetic field measured by each magnetic field sensor.

[0025] One embodiment of the present invention is a biological motion measurement system, which comprises: the above-mentioned biological motion measurement device; and a signal processing unit, which calculates the relative position between each magnetic generator and each magnetic field sensor based on the magnetic field measured by each magnetic field sensor, and in the calculation of the relative position, the signal processing unit performs correction related to the inclination of each magnetic generator or each magnetic field sensor generated during the movement of the biological body based on the orientation measured by each posture sensor.

[0026] In one embodiment of the present invention, the above-mentioned biological motion measurement system is further provided with a geomagnetic sensor, which measures the geomagnetism received by the magnetic field sensor, and the signal processing unit reduces the influence of the geomagnetism from the magnetic field measured by the magnetic field sensor based on the geomagnetism measured by the geomagnetic sensor.

[0027] In one embodiment of the present invention, in the above-mentioned biological motion measurement system, the magnetism received by the plurality of magnetic field sensors is measured, and the tilt is corrected based on the relative coordinates of the plurality of magnetic sensors.

[0028] In one embodiment of the present invention, in the above-mentioned biological motion measurement system, the first part and the other parts are molar parts, and a storage unit is also provided, which stores data showing the positional relationship from the molar part to the front tooth part of the biological body, and the signal processing unit transforms the calculation result of the relative position into the relative position between the front tooth part of the upper jaw and the front tooth part of the lower jaw of the biological body based on the positional relationship.

[0029] In one embodiment of the present invention, the above-mentioned biological motion measurement system is further provided with a transformation table, which is used to transform the magnetic field measured by the magnetic field sensor to the relative position. When the signal processing unit obtains the relative position based on the magnetic field measured by each magnetic field sensor based on the transformation table, it supplements the insufficient position information in the transformation table through interpolation processing.

[0030] In one embodiment of the present invention, in the biological motion measurement system, the interpolation processing is linear interpolation or interpolation using radial basis functions.

[0031] In one embodiment of the present invention, the living body motion measurement system further includes a storage unit that stores a history showing a series of movements of the first part and the other parts of the living body, and the signal processing unit calculates the relative position using the history.

[0032] In one aspect of the present invention, in the biological motion measurement system, the signal processing unit limits the range of the relative position referred to in the conversion table based on a previous calculation result of the relative position.

[0033] In one embodiment of the present invention, in the biological motion measurement system, the magnetic field sensor measures the magnetic field at a sampling rate of 100 Hz or higher.

[0034] In one embodiment of the present invention, in the biological motion measurement system, the magnetic field sensor measures the magnetic field at a sampling rate of 100 Hz or higher, and the posture sensor measures the posture at a sampling rate of 20 Hz or higher.

[0035] Effects of the Invention According to the present invention, it is possible to easily measure the movement of a part of a living body. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a diagram showing an example of the biological motion measurement device according to the first embodiment. Figure 2 This is a diagram showing an example of the biological motion measurement device according to the first embodiment. Figure 3 This is a block diagram showing a configuration example of a main unit of the biological motion measurement device according to the first embodiment. Figure 4 This is a diagram showing an example of the magnet according to the first embodiment. Figure 5 It is an explanatory diagram for explaining the magnetic field of the first embodiment. Figure 6 It is an explanatory diagram for explaining the magnetic field of the first embodiment. Figure 7 This is a diagram showing a configuration example of a conversion table according to the first embodiment. Figure 8 This is an explanatory diagram for explaining an example of a relative position calculation method according to the first embodiment. Figure 9 This is a block diagram showing a configuration example of a main unit of a biological motion measurement device according to a second embodiment. Figure 10 This is a diagram showing an example of arrangement of posture sensors according to the second embodiment. Figure 11 This is a block diagram showing a configuration example of a main unit of a biological motion measurement device according to a third embodiment. Figure 12 It is a diagram showing an example of arrangement of geomagnetic sensors according to the third embodiment. Figure 13 This is a diagram for explaining an example of the geomagnetism reduction method according to the third embodiment. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0038] <First embodiment> Figure 1 and Figure 2 1 is a diagram showing an example of a biological motion measuring device according to a first embodiment. The biological motion measuring device according to this embodiment includes a main device 1 and a magnetic generator 2. The main device 1 and the magnetic generator 2 are arranged on a biological body 200. Figure 1 In the example, the organism 200 is a human. Figure 1 This is a side view of a person's face. Figure 2 In this embodiment, the living body motion measuring device is a measuring device for measuring the relative position of the lower jaw 202 with respect to the upper jaw 201 of a living body 200 .

[0039] exist Figure 1 In the embodiment, the magnetic generator 2 is arranged at the molar part of the upper jaw 201 of the biological body 200. More specifically, as Figure 2 As shown, the magnetic generator 2 is provided on a mouthpiece 211, which is attached to the molar portion of the upper jaw 201 of the living body 200. By attaching the mouthpiece 211 to the molar portion of the upper jaw 201 of the living body 200, the magnetic generator 2 is arranged in the molar portion of the upper jaw 201 of the living body 200.

[0040] like Figure 2 As shown, an example of the magnetic generator 2 is a bipolar magnet. The magnet used for the magnetic generator 2 is, for example, a samarium cobalt magnet or a neodymium magnet. The magnetic flux density of the magnetic generator 2 is preferably 300 millitesla (mT) or more. The magnetic flux density of the magnetic generator 2 is, for example, 400 mT. In addition, a plurality of magnetic generators 2 may be configured. In this embodiment, as an example of the magnetic generator 2, Figure 2 Hereinafter, the magnetic generator 2 may be referred to as a magnet 2 .

[0041] exist Figure 1 In the embodiment, the main device 1 includes a control unit 10, a magnetic field sensor 11, and a battery 12. The main device 1 is arranged on the molar part of the lower jaw 202 of the living body 200. More specifically, as Figure 2 As shown, the main device 1 is provided on a mouthpiece 212, which is attached to the molar portion of the lower jaw 202 of the living subject 200. By attaching the mouthpiece 212 to the molar portion of the lower jaw 202 of the living subject 200, the main device 1 is disposed on the molar portion of the lower jaw 202 of the living subject 200. As a result, the magnetic field sensor 11 included in the main device 1 is disposed on the molar portion of the lower jaw 202 of the living subject 200.

[0042] The magnet 2 and the main body device 1 are respectively provided on the mouthpiece 211 and 212 , thereby making it easy to attach and detach the mouthpiece to the living body 200 .

[0043] The magnetic field sensor 11 measures the magnetic field generated by the magnetic generator 2 using two or more orthogonal measurement axes. By measuring the magnetic field generated by the magnetic generator 2 using two orthogonal measurement axes, the magnetic field sensor 11 can measure two orthogonal magnetic field vectors. By measuring the magnetic field generated by the magnetic generator 2 using three orthogonal measurement axes, the magnetic field sensor 11 can measure three orthogonal magnetic field vectors. The magnetic field sensor 11 can be configured by, for example, a combination of one or more sensors that measure static magnetic fields, such as a Hall effect sensor (MR sensor), a magnetoresistive effect sensor (MR sensor), and a magneto-impedance sensor (MI sensor). Alternatively, multiple magnetic field sensors 11 may be configured. Preferably, the multiple magnetic field sensors 11 are positioned at different distances from a single magnetic generator 2.

[0044] In the main device 1, the control unit 10 performs calculations to calculate the relative position of the lower jaw 202 of the living subject 200 relative to the upper jaw 201 based on the magnetic field measured by the magnetic field sensors 11. More specifically, the control unit 10 includes a signal processing unit that calculates the relative position between each magnetic generator 2 and each magnetic field sensor 11 based on the magnetic field measured by each magnetic field sensor 11. The battery 12 is a power source for supplying power to each component of the main device 1.

[0045] Figure 3 1 is a block diagram showing a configuration example of the main unit 1 of the biological motion measurement device according to the first embodiment. Figure 3 In the embodiment, the main device 1 includes a magnetic field sensor 11 , a battery 12 , a signal processing unit 100 , a storage unit 101 , a wireless communication unit 102 , an antenna 103 , and an RTC (Real-Time Clock) 104 . Figure 3 The signal processing unit 100, storage unit 101, wireless communication unit 102, antenna 103 and RTC 104 of the main device 1 shown correspond to Figure 1 The control unit 10 is shown.

[0046] The signal processing unit 100 includes a CPU (Central Processing Unit). The functions of the signal processing unit 100 are realized by the CPU executing a computer program stored in the storage unit 101. The signal processing unit 100 calculates the relative position between each magnetic generator 2 and each magnetic field sensor 11 based on the magnetic field measured by each magnetic field sensor 11.

[0047] The storage unit 101 includes memories such as ROM (Read Only Memory) and RAM (Random Access Memory), and stores computer programs executed by the CPU of the signal processing unit 100 and various data.

[0048] The wireless communication unit 102 performs wireless communication with the external device 30 by transmitting and receiving wireless signals via the antenna 103. The external device 30 includes an antenna 33, a wireless communication unit 32, and a signal processing unit 31. The wireless communication unit 32 of the external device 30 performs wireless communication with the main device 1 of the biological motion measurement apparatus by transmitting and receiving wireless signals via the antenna 33. As a wireless communication method for wireless communication between the main device 1 of the biological motion measurement apparatus and the external device 30, for example, well-known wireless communication methods such as "Bluetooth (registered trademark)", "Bluetooth Low Energy", "Wi-Fi (registered trademark)", and "LPWA (Low Power Wide Area)" can be applied.

[0049] The RTC 104 generates a time for adding time information (time stamp) to the relative position information indicating the relative position between each magnetic generator 2 and each magnetic field sensor 11 calculated by the signal processing unit 100 .

[0050] The main unit 1 of the biological motion measurement apparatus transmits time-series data (relative position time-series data) of relative position information, which is time-stamped, to the external device 30 via wireless communication. The relative position information indicates the relative positions between each magnetic generator 2 and each magnetic field sensor 11, as calculated by the signal processing unit 100. Based on the relative position time-series data of the biological subject 200 received from the main unit 1 of the biological motion measurement apparatus via wireless communication, the external device 30 performs calculations for analyzing the jaw movement of the biological subject 200 via the signal processing unit 31. For example, the signal processing unit 31 of the external device 30 calculates the trajectory of the jaw movement of the biological subject 200 based on the relative position time-series data of the biological subject 200.

[0051] The following describes in detail the measurement performed by the biological motion measurement device according to this embodiment.

[0052] The first location where one or more magnetic generators 2 are disposed in the living body 200 may be any location that is linked to either the upper jaw 201 or the lower jaw 202 of the living body 200. Furthermore, the location where one or more magnetic field sensors 11 are disposed in the living body 200 may be any location that is linked to either the upper jaw 201 or the lower jaw 202 of the living body 200 that is different from the first location.

[0053] In order to measure the relative position of the lower jaw 202 of the biological subject 200 relative to the upper jaw 201, the magnetic generator 2 and the magnetic field sensor 11 are respectively arranged on different jaws (opposite jaws). Figure 1 and Figure 2As shown, when the magnetic generator 2 is placed on the upper jaw 201, the magnetic field sensor 11 is placed on the lower jaw 202. Conversely, when the magnetic generator 2 is placed on the lower jaw 202, the magnetic field sensor 11 is placed on the upper jaw 201. In this way, the magnetic generator 2 and the magnetic field sensor 11 can be placed on the opposing jaws.

[0054] like Figure 2 As shown, the magnetic poles of the magnetic generator 2 are arranged in the movable direction 300 of the first part (upper jaw 201) where the magnetic generator 2 is arranged and the part (lower jaw 202) where the main body device 1 is arranged. Figure 2 In the embodiment, the movable direction 300 is the opening direction. Therefore, the magnetic generator 2 is arranged so that the magnetic poles face the opening direction 300. In addition, the arrangement of the N pole and the S pole may be reversed.

[0055] In addition, the magnetic field generated by the magnet 2 attenuates in proportion to the square of the distance. Therefore, it is preferable to configure the distance between the magnet 2 and the magnetic field sensor 11 as short as possible when the opening is maximum in order to prevent a decrease in the magnetic field measurement sensitivity for measuring the magnetic field generated by the magnet 2. Specifically, Figure 1 As shown, the magnet 2 and the magnetic field sensor 11 are preferably arranged on the opposing teeth. In addition, since the distance between the opposing teeth when the molar part is the largest opening is shorter than that of the front tooth part, Figure 1 As shown, the magnet 2 and the magnetic field sensor 11 are preferably arranged on the molars of the upper jaw 201 and the lower jaw 202, respectively.

[0056] However, when measuring an opening movement at a relatively close distance, such as a hinge movement when gently opening and closing the mouth, the magnet 2 and the magnetic field sensor 11 do not need to be separately arranged on the opposing teeth, the molars of the upper jaw 201, and the lower jaw 202. This is because the distance between the magnet 2 and the magnetic field sensor 11 does not extend to such an extent that an unacceptable decrease in magnetic field measurement sensitivity occurs, and the decrease in magnetic field measurement sensitivity falls within an acceptable range. In addition, even when measuring the maximum opening movement, when measuring an opening movement at a relatively close distance is important, the magnet 2 and the magnetic field sensor 11 do not need to be separately arranged on the opposing teeth, the molars of the upper jaw 201, and the lower jaw 202. For example, when measuring the body 200 while grinding (grinding) the teeth is important, the magnet 2 and the magnetic field sensor 11 do not need to be separately arranged on the opposing teeth, the molars of the upper jaw 201, and the lower jaw 202.

[0057] Furthermore, the magnetic field sensor 11 is preferably capable of measuring two or more degrees of freedom, i.e., magnetic field vectors along two orthogonal axes, in order to calculate at least a two-dimensional relative position (the trajectory of jaw movement) as the relative position of the lower jaw 202 relative to the upper jaw 201 of the living body 200. Furthermore, in order to measure both frontal and side views of jaw movement, the magnetic field sensor 11 is preferably capable of measuring three degrees of freedom, i.e., magnetic field vectors along three orthogonal axes.

[0058] The material of magnet 2 is irrelevant as long as it generates a magnetic field. To ensure that the fit of the organism 200 is not compromised, magnet 2 is preferably as small as possible and not awkward when installed. Based on this requirement, magnet 2 is preferably a neodymium magnet or samarium-cobalt magnet, both of which have relatively strong magnetic force. Furthermore, to balance the magnetic field generated by magnet 2 with the fit, the thickness of magnet 2 is preferably between 1.5 and 4 mm, and more preferably between 5 and 10 mm square.

[0059] The shape of the magnet 2 can be a cube, a rectangular parallelepiped, or a cylinder. However, in order to improve the sensitivity of magnetic field measurement when the distance between the magnet 2 and the magnetic field sensor 11 is short, a cylindrical shape is preferred. This is because, when the magnet 2 is a cube or a rectangular parallelepiped, as shown in FIG. Figure 4 As shown in (1), since a substantially uniform magnetic field is generated around the periphery 311 of the magnetic field sensor 11 located near the magnet 2, even if the relative position of the magnetic field sensor 11 and the magnet 2 changes, the magnetic field vector measured by the magnetic field sensor 11 hardly changes, and thus the magnetic field measurement sensitivity decreases. On the other hand, in the case where the magnet 2 is cylindrical, as shown in FIG. Figure 4 As shown in (2), since the magnetic field generated around 312 of the magnetic field sensor 11 located near the magnet 2 changes depending on the position, if the relative position of the magnetic field sensor 11 and the magnet 2 changes, the magnetic field vector measured by the magnetic field sensor 11 also changes, thereby achieving good magnetic field measurement sensitivity.

[0060] Furthermore, when measurement is important when the distance between magnetic field sensor 11 and magnet 2 is long, good magnetic field measurement sensitivity can be achieved even when magnet 2 is in the shape of a cube or a rectangular parallelepiped. Therefore, the shape of magnet 2 is not a problem. For example, when measuring the trajectory of jaw movement at maximum opening, the shape of magnet 2 is not a problem even when it is in the shape of a cube or a rectangular parallelepiped. In addition, when the shape of the magnet 2 is a cube or a rectangular parallelepiped, not only can the distance between the magnet 2 and the opening direction of the magnetic field sensor 11 be extended, but also Figure 4 As shown in (3), the magnetic field sensor 11 is shifted to a position where the vector of two or more components of the magnetic field generated by the magnet 2 changes. Figure 4In the example of (3), the magnetic field sensor 11 is arranged at a position deviated from the position 311 where the magnetic field lines extend perpendicularly to the surface of the north pole of the magnet 2, and at the position of the magnetic field sensor 11, the vectors of two or more components of the magnetic field generated by the magnet 2 change. In this way, by configuring the magnet 2 in the shape of a cube or a rectangular parallelepiped, position estimation can be performed without using the magnetic field near the surface of the magnet 2. For example, the magnetic field sensor 11 can be set on a tooth adjacent to a tooth on which the magnet 2 in the shape of a cube or a rectangular parallelepiped is arranged. In this way, by using the magnet 2 in the shape of a cube or a rectangular parallelepiped, it is easy to identify the direction of the magnetic pole, thereby simplifying the process of mounting the magnet 2 on the mouthguard.

[0061] When the magnet 2 is placed on the upper jaw 201 and the magnetic field sensor 11 is placed on the lower jaw 202 , the magnetic field vector measured by the magnetic field sensor 11 changes depending on the relative position of the lower jaw 202 with respect to the upper jaw 201 . Figure 5 The diagram shows examples of magnet 2, the magnetic field generated by magnet 2, and the positions (positions P1, P2, P3, and P4) of magnetic field sensor 11. Magnetic field sensor 11 measures magnetic field vectors (x, y, and z components) along three orthogonal axes (x, y, and z).

[0062] exist Figure 5 In the figure, when magnetic field sensor 11 is at positions P1 or P2, the magnetic field vector measured by magnetic field sensor 11 is only the z component. For ease of explanation, the magnetic field vector measured by magnetic field sensor 11 at position P1 is "Bx = 0, By = 0, Bz = 3000." "Bx, By, Bz" represents the magnetic flux density, where Bx is the x component, By is the y component, and Bz is the z component, and the unit is mT. At position P2, where the distance from magnet 2 is longer than position P1, the magnetic field attenuates proportionally to the square of the distance, and is therefore measured as a smaller magnetic field. For ease of explanation, the magnetic field vector measured by magnetic field sensor 11 at position P2 is "Bx = 0, By = 0, Bz = 1000."

[0063] Furthermore, when magnetic field sensor 11 moves from position P1 to positions P3 and P4 in the y-axis direction, the magnetic field generated by magnet 2 obliquely penetrates magnetic field sensor 11, generating a y-component of the magnetic field vector. For ease of illustration, the magnetic field vector measured by magnetic field sensor 11 at position P3 is "Bx = 0, By = -500, Bz = 2000." For ease of illustration, the magnetic field vector measured by magnetic field sensor 11 at position P4 is "Bx = 0, By = 500, Bz = 2000." Similarly, when magnetic field sensor 11 moves from position P1 in the x-axis direction, an x-component of the magnetic field vector is generated.

[0064] In this way, the size and direction of the magnetic field change according to the relative position of the lower jaw 202 with respect to the upper jaw 201. Therefore, by using a magnetic field sensor 11 capable of measuring magnetic field vectors of two or more orthogonal axes, the relative position of at least two orthogonal axes can be measured as the relative position of the lower jaw 202 with respect to the upper jaw 201. Thus, the trajectory of at least two-dimensional jaw movement can be calculated. Furthermore, by using a magnetic field sensor 11 capable of measuring magnetic field vectors of three orthogonal axes, the relative position of three orthogonal axes can be measured as the relative position of the lower jaw 202 with respect to the upper jaw 201. Thus, the trajectory of three-dimensional jaw movement can be calculated.

[0065] Furthermore, by arranging multiple magnetic field sensors 11 at different distances from a single magnet 2, the dynamic range of the magnetic field sensors 11 can be visually expanded, thereby widening the measurable range of the relative position of the lower jaw 202 relative to the upper jaw 201. For example, if both magnetic field sensors 11 (11A and 11B) can measure from 0 mT to 4 mT, magnetic field sensor 11A can be positioned near magnet 2, while magnetic field sensor 11B can be positioned farther from the magnet 2 than magnetic field sensor 11A. Consequently, even if magnetic field sensor 11A saturates above the measurement value of "4 mT" near magnet 2, magnetic field sensor 11B can still output a valid measurement value. Furthermore, even if the magnetic field measurement sensitivity of magnetic field sensor 11B decreases as the distance from magnet 2 increases, magnetic field sensor 11A can still measure with good magnetic field measurement sensitivity. Therefore, compared with the case of using a single magnetic field sensor 11, when using two magnetic field sensors 11A and 11B, the measurable range of the relative position of the lower jaw 202 relative to the upper jaw 201 can be expanded by approximately the distance from the magnetic field sensor 11A to the magnetic field sensor 11B.

[0066] Furthermore, it is preferable to arrange the magnet 2 and magnetic field sensor 11 so that the minimum distance between them is at least a certain length. This is because, since the strength of the magnetic field decays proportionally to the square of the distance, the rate of change of the magnetic field relative to position changes is small at a certain distance from the magnet 2. However, the rate of change of the magnetic field relative to position changes is large near the magnet 2. Therefore, if the magnetic field sensor 11 is arranged too close to the magnet 2, the dynamic range required of the magnetic field sensor 11 increases, resulting in increased costs for the magnetic field sensor 11. For example, when measuring jaw movement, including at maximum jaw opening, it is preferable to arrange the magnet 2 and magnetic field sensor 11 so that the minimum distance between them is approximately 5 mm to 10 mm.

[0067] In addition, since the short-circuit distance of the magnetic flux of the bipolar magnet is long, the attenuation of the magnetic field corresponding to the distance from the magnet is small. Therefore, the magnet used as the magnetic generator 2 is preferably bipolar.

[0068] The magnetic pole (magnetization direction) of magnet 2 is preferably oriented toward opening direction 300. This is because oriented toward opening direction 300 reduces errors in estimating the relative position (relative position) between magnet 2 and magnetic field sensor 11. Figure 6 This is the case where the magnetization direction of the magnet 2 is directed toward the opening direction 300 ( Figure 6 (1)), and when the magnetization direction of the magnet 2 is directed in a direction different from the opening direction 300 ( Figure 6 (2) Explanatory diagram. The magnet 2 is placed on the upper jaw 201 , and the magnetic field sensor 11 is placed on the lower jaw 202 .

[0069] exist Figure 6 The upper part of (1) and (2) shows the magnetic fields 321 and 322 of the yz plane of the y-axis and the z-axis when the value of the x-axis is "x=0" in the magnetic field generated by the magnet 2. In addition, the magnetic field sensor 11 moves within the moving ranges 323 and 324 shown by the single-dot chain line. In either of the magnetic fields 321 and 322 of the yz plane, the change in the relative position between the magnet 2 and the magnetic field sensor 11 caused by the movement of the magnetic field sensor 11 within the moving ranges 323 and 324 can be measured as a change in the magnetic fields 321 and 322 (a change in the magnetic field vector). Therefore, in the yz plane, whether Figure 6 (1) The magnetic field 321 or Figure 6 The magnetic field 322 of (2) can estimate the relative position between the magnet 2 and the magnetic field sensor 11 based on the magnetic field vector measured by the magnetic field sensor 11.

[0070] exist Figure 6 The lower parts of (1) and (2) show the magnetic fields 325 and 326 of the x-axis and z-axis in the xz plane when the y-axis value is "y=0" in the magnetic field generated by the magnet 2. When the magnetization direction of the magnet 2 is oriented toward the opening direction 300 ( Figure 6 (1)), the magnetic field 325 in the xz plane is the same as the magnetic field 321 in the yz plane. Therefore, in the xz plane, the relative position between the magnet 2 and the magnetic field sensor 11 can be estimated based on the magnetic field vector measured by the magnetic field sensor 11. When the magnetization direction of the magnet 2 is oriented toward the opening direction 300 ( Figure 6 (1)), the relative position between the magnet 2 and the magnetic field sensor 11 can be estimated three-dimensionally.

[0071] On the other hand, when the magnetization direction of the magnet 2 is directed in a direction different from the opening direction 300 ( Figure 6(2)), the magnetic field 326 in the xz plane is different from the magnetic field 322 in the yz plane and is oriented in the y-axis direction. At this time, at points on the same circumference with a radius from the center of the magnet 2 (points in the diagram representing the magnetic field 326), the magnetic field is equally oriented in the y-axis direction and is at the same distance from the magnet 2, so the magnitude of the magnetic field is also the same. Therefore, even if the magnetic field sensor 11 moves at each point on the circumference, the magnetic field vectors measured by the magnetic field sensor 11 are all the same, so it is impossible to distinguish each point on the circumference based on the magnetic field vector measured by the magnetic field sensor 11. Therefore, when the magnetization direction of the magnet 2 is oriented in a direction different from the opening direction 300 ( Figure 6 (2)) In the xz plane, it is difficult to estimate the relative position between magnet 2 and magnetic field sensor 11 based on the magnetic field vector measured by magnetic field sensor 11, and a significant error in the relative position estimation may occur. For this reason, the magnetic pole (magnetization direction) of magnet 2 is preferably oriented in the opening direction 300. For example, when calculating the trajectory of a three-dimensional jaw movement, the accuracy of the calculation is improved by aligning the magnetic pole (magnetization direction) of magnet 2 in the opening direction 300.

[0072] The signal processing unit 100 of the main device 1 calculates the relative position between each magnetic generator 2 and each magnetic field sensor 11 based on the magnetic field measured by each magnetic field sensor 11. When measuring one-dimensional motion, the magnetic field generated by magnet 2 decays proportionally to the square of the distance. This allows estimation of the relative position "x" between magnet 2 and magnetic field sensor 11 based on the one-dimensional magnetic field vector "x component Bx" measured by magnetic field sensor 11. Specifically, the function f(Mx) shown in the following equation is used to determine the relative position x based on the one-dimensional magnetic field Mx. x=f(Mx)

[0073] On the other hand, when measuring three-dimensional motion, the three-dimensional motion (x-axis, y-axis, and z-axis) of the relative position between magnet 2 and magnetic field sensor 11 and the three-dimensional magnetic field values ​​(x-axis, y-axis, and z-axis) do not affect each axis independently. For example, when relative motion occurs in the x-axis direction, the magnetic field not only affects the x-axis component (x component), but also the y-axis component (y component) and the z-axis component (z component). Therefore, the relative position between magnet 2 and magnetic field sensor 11 cannot be determined for each axis by using the components Bx, By, and Bz of each axis independently from the three-dimensional magnetic field vector (x component Bx, y component By, and z component Bz) measured by magnetic field sensor 11, as described above with "x = f(Mx)".

[0074] Therefore, when measuring three-dimensional motion, it is necessary to consider the crosstalk between the three-dimensional values ​​of the magnetic field (x-axis, y-axis, and z-axis) for each axis. Specifically, the functions fx(Mx, My, Mz), fy(Mx, My, Mz), and fz(Mx, My, Mz) that determine the relative position "x, y, z" between magnet 2 and magnetic field sensor 11 from the three-dimensional magnetic field "Mx, My, Mz" are used, as shown in the following equations. x=fx(Mx,My,Mz) y=fy(Mx,My,Mz) z=fz(Mx,My,Mz)

[0075] Functions fx(Mx, My, Mz), fy(Mx, My, Mz), and fz(Mx, My, Mz) can also be obtained in advance through experiments or simulations.

[0076] In this embodiment, a method of making Figure 7 The conversion table 100T shown in FIG. The conversion table 100T is a conversion table for obtaining the relative position "x, y, z" based on the magnetic field vector "Bx, By, Bz" measured by the magnetic field sensor 11. Figure 7 The numerical values ​​in the conversion table 100T are shown for ease of explanation.

[0077] exist Figure 7 In the transformation table 100T, the numerical value groups of the components Bx, By, Bz of the magnetic field vector "Bx, By, Bz" (magnetic field component groups) are associated with the numerical value groups of the components x, y, z of the relative position "x, y, z" (relative position component groups) stored. As an example of a method for making the transformation table 100T, in a sample of an actual biological body 200, the magnet 2 and the magnetic field sensor 11 are arranged at known relative positions "x, y, z", and the magnetic field vector "Bx, By, Bz" is measured by the magnetic field sensor 11. The measurement is performed at multiple known relative positions "x, y, z". Then, the magnetic field vector "Bx, By, Bz" of each measurement result is associated with the known relative position "x, y, z", as shown in FIG. Figure 7 The data are recorded in a table format, thereby creating a conversion table 100T.

[0078] In the main body 1 of the biological motion measurement device, the storage unit 101 stores a conversion table 100T. The signal processing unit 100 uses this conversion table 100T to determine the relative position "x, y, z" based on the magnetic field vector "Bx, By, Bz" measured by the magnetic field sensor 11. For example, if the magnetic field vector measured by the magnetic field sensor 11 is "Bx = -1000, By = -1000, Bz = 0, in units of mT," the signal processing unit 100 obtains the relative position "x = -10.0, y = -10.0, z = 50.0, in units of mm" from the conversion table 100T. For example, if the magnetic field vector measured by the magnetic field sensor 11 is "Bx = 0, By = 0, Bz = 2005, in units of mT," the signal processing unit 100 obtains the relative position "x = 0, y = 0, z = 30.5, in units of mm" from the conversion table 100T.

[0079] The number of combinations of magnetic field component groups and relative position component groups that can be stored in transformation table 100T is limited. Therefore, it is impossible to store in transformation table 100T combinations of magnetic field component groups and relative position component groups corresponding to all magnetic field vectors "Bx, By, Bz" measurable by magnetic field sensor 11. Therefore, if a magnetic field component group that matches the magnetic field vector "Bx, By, Bz" measured by magnetic field sensor 11 does not exist in transformation table 100T, signal processing unit 100 uses the relative position component group associated with the magnetic field component group near the magnetic field vector "Bx, By, Bz" in transformation table 100T to determine the relative position "x, y, z" using a predetermined interpolation method. An example of this interpolation method is the nearest-neighbor interpolation method.

[0080] In the nearest neighbor interpolation method, the signal processing unit 100 selects the magnetic field component group closest to the magnetic field vector "Bx, By, Bz" measured by the magnetic field sensor 11 in the transformation table 100T, and obtains the relative position component group associated with the selected magnetic field component group from the transformation table 100T.

[0081] In the aforementioned nearest neighbor interpolation method, since the relative positions "x, y, z" are limited to the relative position component groups present in the transformation table 100T, the estimated errors of the relative positions "x, y, z" may be large. Therefore, examples of other interpolation methods include linear interpolation and interpolation using radial basis functions (RBFs). These other interpolation methods are less complex and can produce good results in applications involving jaw movement measurement.

[0082] Furthermore, the form is not limited to the table form such as the above-mentioned conversion table 100T, and for example, a form or function such as a polynomial expression or a network structure may be used.

[0083] Furthermore, the signal processing unit 100 may store a history of the relative position between the magnet 2 and the magnetic field sensor 11 in the storage unit 101, and use this history to calculate the relative position in the future. For example, since the lower jaw does not move significantly rapidly during human jaw movement, the most reasonable relative position can be estimated based on the series of past relative position movements. This improves the accuracy of the relative position.

[0084] In addition, the signal processing unit 100 may also limit the range of relative positions referenced in the conversion table 100T based on the calculation result of the relative position just before. Figure 8 As shown, a trajectory 330 (relative position history) of the relative position of the magnetic field sensor 11 with respect to the magnet 2 is stored in the storage unit 101. When calculating the next relative position P_t, the signal processing unit 100 limits the range of relative positions referenced in the conversion table 100T based on the immediately preceding relative position calculation result P_t-1. For example, when calculating the next relative position P_t, the signal processing unit 100 only references a range of a certain size (e.g., 2 mm x 2 mm) surrounding the immediately preceding relative position calculation result P_t-1 within the relative position component group within the conversion table 100T as a search range. This reduces the amount of referenced data compared to when the entire data within the conversion table 100T is referenced as the search range, thereby shortening processing time. Furthermore, even when the relative positions are completely different, if similar magnetic field vectors exist, it is possible to prevent incorrect relative positions from being determined from the conversion table 100T. This improves the accuracy of relative position estimation.

[0085] In addition, the signal processing unit 100 can also use the past relative position trajectory (the history of relative position) to learn the machine learning model through a machine learning algorithm with a network structure such as LSTM (Long-short term model), and use the learned machine learning model to perform subsequent relative position calculations.

[0086] In addition, it is described that the magnet 2 and the magnetic field sensor 11 are Figure 1The present invention is an example of a relative position calculation method for determining the relative position between the front teeth of the upper jaw 201 and the front teeth of the lower jaw 202 when the molars are respectively arranged in the upper jaw 201 and the lower jaw 202. In the main body device 1 of the biological motion measurement device, data showing the positional relationship from the molar part to the front teeth part in the biological body 200 (molar front teeth position relationship data) are pre-stored in the storage unit 101. The molar front teeth position relationship data is data obtained by measuring the three-dimensional relative position of the front teeth part of the biological body 200 relative to the molar part in advance. Based on the molar front teeth position relationship data, it is possible to obtain the relative position of the front teeth part of the biological body 200 from the magnet 2 and the magnetic field sensor 11 as shown in FIG. Figure 1 The three-dimensional relative positions of the magnetic field sensors 11 located in the molars of the upper jaw 201 and lower jaw 202, respectively, are converted into the three-dimensional relative positions of the anterior teeth. Based on the molar-anterior tooth positional relationship data, the signal processing unit 100 converts the relative positions between the molar magnets 2 and the magnetic field sensors 11, calculated based on the three-dimensional magnetic field vectors measured by the molar magnetic field sensors 11, into the relative positions between the anterior teeth of the upper jaw 201 and the anterior teeth of the lower jaw 202. This allows the trajectory of the anterior teeth of the lower jaw 202 relative to the anterior teeth of the upper jaw 201 to be calculated as the jaw motion of the living subject 200.

[0087] Furthermore, when measuring three-dimensional jaw motion, it is preferable to use a three-axis orthogonal magnetic field sensor 11. By using a three-axis orthogonal magnetic field sensor 11, three-dimensional jaw motion can be measured with a minimal configuration consisting of a single magnet 2 and a single magnetic field sensor 11. This contributes to the miniaturization and cost reduction of biological motion measurement devices.

[0088] While the above embodiment measures the movement of the jaw of a living subject 200, the measurement is not limited to jaw movement. For example, the measurement can also be applied to the measurement of movement of a limb or finger. In this case, by arranging the magnetic poles of the magnet (magnetic generator) 2 in the direction of movement relative to the first portion where the magnet 2 is positioned and the other portion where the magnetic field sensor 11 is positioned, it is possible to more effectively detect movement of a joint or other similar object.

[0089] According to the first embodiment, the relative motion between the reference portion and the movable portion in a living body can be easily measured. For example, the relative motion between the upper jaw 201 and the lower jaw 202 (movable portion) can be easily measured with the upper jaw 201 as the reference portion.

[0090] Furthermore, the magnetic field sensor 11 preferably measures the magnetic field at a sampling rate of 100 Hz or higher. This is because if the sampling rate of the magnetic field sensor 11 is lower than 100 Hz, it is difficult to accurately measure the movement of the jaw.

[0091] <Second embodiment> Figure 9 : is a block diagram showing a configuration example of a main unit 1a of a biological motion measurement device according to a second embodiment. Figure 9 In, with Figure 3 The corresponding parts of the various parts are marked with the same symbols and their descriptions are omitted. Figure 9 The main device 1a shown is different from the first embodiment. Figure 3 The main device 1 also includes a posture sensor 13.

[0092] Figure 10 An example of arrangement of the posture sensor 13 according to the second embodiment is shown. Figure 10 This is a side view of the face of a person (organism 200) as viewed from the side. Figure 10 As shown, the posture sensor 13 is arranged on the lower jaw 202 of the living body 200. Specifically, the main device 1a is as shown in FIG. Figure 2 As shown, the main device 1a is provided on a mouthpiece 212, which is attached to the molar portion of the lower jaw 202 of the living subject 200. By attaching the mouthpiece 212 to the molar portion of the lower jaw 202 of the living subject 200, the main device 1a is disposed on the molar portion of the lower jaw 202 of the living subject 200. As a result, the magnetic field sensor 11 and the posture sensor 13 included in the main device 1a are disposed on the molar portion of the lower jaw 202 of the living subject 200.

[0093] In addition, the magnet 2 is Figure 2 The magnet 2 is provided on a tooth guard 211, which is mounted on the molar portion of the upper jaw 201 of the living body 200. By mounting the tooth guard 211 on the molar portion of the upper jaw 201 of the living body 200, the magnet 2 is arranged on the molar portion of the upper jaw 201 of the living body 200.

[0094] The reason why the posture sensor 13 is provided in this embodiment will be described. In the magnet 2 or magnetic field sensor 11 ( Figure 10 In the example of the magnetic field sensor 11, if the angle θ between the orientation 410 and the horizontal direction 400 remains unchanged and the magnet 2 or the magnetic field sensor 11 moves parallel to the horizontal direction 400, thereby changing the relative position between the magnet 2 and the magnetic field sensor 11, the signal processing unit 100 can calculate the relative position based on the conversion table 100T, as described in the first embodiment. However, when the angle θ changes, the magnitude of the magnetic field vector measured by the magnetic field sensor 11 remains unchanged, but its direction changes. The calculation of the relative position between the magnet 2 and the magnetic field sensor 11 depends on both the magnitude and direction of the magnetic field vector measured by the magnetic field sensor 11. Therefore, if the angle θ changes, the direction of the magnetic field vector measured by the magnetic field sensor 11 also changes, reducing the accuracy of the relative position calculation.

[0095] Therefore, in this embodiment, a posture sensor 13 is provided to detect the change in the angle θ. Figure 10 As shown, the posture sensor 13 and the magnetic field sensor 11 are arranged together on the lower jaw 202 , and the orientation 410 of the magnetic field sensor 11 is measured by the posture sensor 13 .

[0096] The posture sensor 13 is preferably located on the same jaw as the magnetic field sensor 11. Furthermore, the posture sensor 13 preferably has the same degrees of freedom as the magnetic field sensor 11. For example, if the magnetic field sensor 11 measures a three-dimensional magnetic field vector, the posture sensor 13 preferably also measures a three-dimensional orientation. The posture sensor 13 is composed of a combination of one or more of a gyroscope, an acceleration sensor, and a geomagnetic sensor. The posture sensor 13 outputs information indicating the orientation 410 (posture), such as Euler angles or quaternions.

[0097] The signal processing unit 100 performs correction related to the tilt of each magnet 2 or each magnetic field sensor 11 generated when the biological body 200 moves based on the orientation 410 measured by the posture sensor 13 when calculating the relative position between the magnet 2 and the magnetic field sensor 11. Figure 10 As shown, since the posture sensor 13 is arranged on the same jaw as the magnetic field sensor 11, the inclination of the posture sensor 13 is the same as the inclination of the magnetic field sensor 11. Therefore, the inclination of the magnetic field sensor 11 can be corrected based on the orientation 410 measured by the posture sensor 13 (i.e., the orientation 410 of the magnetic field sensor 11).

[0098] Specifically, based on the orientation 410 measured by the posture sensor 13, the signal processing unit 100 rotates the magnetic field vector in a direction opposite to the direction of change in orientation 410 by an amount equal to the change in orientation 410 from the orientation 410 at the start of measurement (the initial orientation). This allows the magnetic field vector obtained at the initial angle θ to be reproduced even if the angle θ changes from the initial angle θ at the start of measurement. In other words, this rotation allows the magnetic field vector to be obtained while maintaining the initial angle θ at the start of measurement. The signal processing unit 100 uses this rotated magnetic field vector to calculate the relative position between the magnet 2 and the magnetic field sensor 11. This prevents a decrease in the accuracy of the relative position calculation.

[0099] Furthermore, the posture sensor 13 only needs to be arranged on at least one of the upper jaw 201 where the magnet 2 is arranged and the lower jaw 202 where the magnetic field sensor 11 is arranged.

[0100] In addition, the posture sensor 13 can be arranged in addition to the jaw (in which the magnetic field sensor 11 is arranged) Figure 10In the example of the lower jaw 202), it can also be configured in the other jaw (in the configuration of the magnet 2) Figure 10 In this example, the upper jaw 201 is used. When the person 200 changes their posture (particularly by tilting their head), the angle θ can vary significantly. For example, when the person faces forward (horizontally 400 degrees), the angle θ differs significantly from when the person faces the ground or the sky. Furthermore, the angle θ of both the upper jaw 201 and the lower jaw 202 varies.

[0101] To address this situation, posture sensors 13 are disposed on both the upper jaw 201 and the lower jaw 202. When calculating the relative position between the magnet 2 and the magnetic field sensor 11, the signal processing unit 100 controls the direction and amount of rotation of the magnetic field vector measured by the magnetic field sensor 11 based on the orientation 410 measured by each posture sensor 13 disposed on each jaw.

[0102] Specifically, the signal processing unit 100 first rotates the magnetic field vector in a direction opposite to the direction of change in the lower jaw's orientation 410, based on the orientation 410 of the lower jaw 202 measured by the posture sensor 13 of the lower jaw 202 equipped with the magnetic field sensor 11, by an amount equal to the change in the lower jaw's orientation 410 from the lower jaw's initial orientation at the start of measurement (the lower jaw's initial orientation). Next, the signal processing unit 100 rotates the magnetic field vector in a direction opposite to the direction of change in the upper jaw's orientation 410, based on the orientation 410 of the upper jaw measured by the posture sensor 13 of the upper jaw 201 equipped with the magnet 2, by an amount equal to the change in the upper jaw's orientation 410 from the upper jaw's initial orientation at the start of measurement (the upper jaw's initial orientation). The signal processing unit 100 uses this rotated magnetic field vector to calculate the relative position between the magnet 2 and the magnetic field sensor 11. This prevents a decrease in the accuracy of the relative position calculation.

[0103] Alternatively, instead of configuring the posture sensor 13 on both the upper jaw 201 and the lower jaw 202 , the posture sensor 13 configured on the lower jaw 202 may be a sensor that can simultaneously measure the orientation 410 of the lower jaw and the relative angle of the lower jaw 202 with respect to the upper jaw 201 .

[0104] According to the second embodiment, when measuring jaw movement of a person (living subject 200) in daily life, for example, it is possible to prevent a decrease in jaw movement measurement accuracy even if the living subject 200 adopts any posture during measurement. This alleviates restrictions on the person's movements during measurement. This also facilitates obtaining measurement data for analyzing the impact of individual lifestyles and behavior patterns on jaw movement.

[0105] Furthermore, the signal processing unit 100 may measure the jaw movement with six degrees of freedom in the living body 200 based on the three-dimensional magnetic field vector measured by the magnetic field sensor 11 and the three-dimensional orientation 410 measured by the posture sensor 13 .

[0106] According to the second embodiment, in addition to the same effects as those of the first embodiment, an effect of preventing a decrease in measurement accuracy by correcting the influence of a change in the posture of the living body 200 on the measurement can be obtained.

[0107] Furthermore, it is preferred that the magnetic field sensor 11 measure the magnetic field at a sampling rate of 100 Hz or higher, and the posture sensor 13 measure the posture at a sampling rate of 20 Hz or higher. This is because, since jaw tilt changes relatively slowly, the posture sensor 13 does not need to have a sampling rate as high as the magnetic field sensor 11. However, if the sampling rate of the posture sensor 13 is lower than 20 Hz, it will be difficult to accurately measure jaw tilt.

[0108] <Third embodiment> Figure 11 : is a block diagram showing a configuration example of a main unit 1b of a biological motion measurement device according to a third embodiment. Figure 11 In, with Figure 3 The corresponding parts of the various parts are marked with the same symbols and their descriptions are omitted. Figure 11 The main device 1b shown is different from the first embodiment. Figure 3 The main device 1 further includes a geomagnetic sensor 14. The geomagnetic sensor 14 measures a geomagnetic vector indicating the magnitude and direction of the geomagnetic field. The geomagnetic sensor 14 preferably measures a three-dimensional geomagnetic vector. In this embodiment, the magnetic field sensor 11 measures a three-dimensional magnetic field vector, and the geomagnetic sensor 14 measures a three-dimensional geomagnetic vector.

[0109] Figure 12 An example of arrangement of the geomagnetic sensor 14 according to the third embodiment is shown. Figure 12 This is a front view of the face of a person (living body 200) viewed from the front. The location where the geomagnetic sensor 14 is disposed may be any location where the geomagnetism received by the magnetic field sensor 11 can be measured.

[0110] like Figure 12 As shown, the geomagnetic sensor 14 is arranged at a distance greater than or equal to a certain distance from the magnet 2. The reason for arranging the geomagnetic sensor 14 at a distance greater than or equal to a certain distance from the magnet 2 is to suppress the influence of the magnetic field generated by the magnet 2 on the geomagnetic sensor 14.

[0111] exist Figure 12In the example, the geomagnetic sensor 14 is arranged on the second molar portion opposite to the first molar portion on the lower jaw 202 of the living body 200 where the magnetic field sensor 11 is arranged. Specifically, the geomagnetic sensor 14 is provided on the second tooth guard 212. Figure 2 The tooth guard 212 (first tooth guard) shown is also attached to the second molar portion of the lower jaw 202 of the living body 200. By attaching the second tooth guard 212 to the second molar portion of the lower jaw 202 of the living body 200, the geomagnetic sensor 14 is arranged on the second molar portion of the lower jaw 202 of the living body 200.

[0112] exist Figure 12 In the example, the main device 1b including the magnetic field sensor 11 is disposed on the first molar portion of the lower jaw 202 of the living body 200. Therefore, in the lower jaw 202 of the living body 200, wiring is provided to connect the geomagnetic sensor 14 disposed on the second molar portion to the main device 1b disposed on the first molar portion.

[0113] In addition, if Figure 2 As shown, the magnet 2 is provided on a mouthpiece 211, which is attached to the molar portion of the upper jaw 201 of the living body 200. By attaching the mouthpiece 211 to the molar portion of the upper jaw 201 of the living body 200, the magnet 2 is arranged on the molar portion of the upper jaw 201 of the living body 200.

[0114] In addition, the place where the geomagnetic sensor 14 is arranged can be any place where the geomagnetism received by the magnetic field sensor 11 can be measured and the influence of the magnetic field generated by the magnet 2 is within the allowable range. As an example of a place that is kept at a certain distance from the magnet 2 arranged in the molar part, the geomagnetic sensor 14 can also be arranged in the molar part or the front tooth part. Figure 12 In the example, in order to keep as much distance as possible from the magnet 2 arranged on the molar portion of the upper jaw 201, the geomagnetic sensor 14 is arranged on the molar portion on the opposite side of the magnet 2 in the lower jaw 202.

[0115] In this embodiment, a geomagnetic sensor 14 is provided, and the signal processing unit 100 performs a calculation to reduce the influence of geomagnetism from the magnetic field vector measured by the magnetic field sensor 11 based on the geomagnetic field measured by the geomagnetic sensor 14. Specifically, the signal processing unit 100 subtracts the geomagnetic vector measured by the geomagnetic sensor 14 from the magnetic field vector measured by the magnetic field sensor 11. The signal processing unit 100 uses this subtracted magnetic field vector to calculate the relative position between the magnet 2 and the magnetic field sensor 11. This prevents a decrease in the accuracy of the relative position calculation due to the influence of geomagnetism.

[0116] In addition, as another geomagnetic reduction method for reducing the influence of geomagnetism from the magnetic field vector measured by the magnetic field sensor 11, there is a method of using the polarity of a magnet without using the geomagnetic sensor 14. In this other geomagnetic reduction method, Figure 3 The main device 1 is shown. Figure 13 This is a diagram for explaining a method of reducing the geomagnetic field using the polarity of a magnet. Figure 13 An example of arrangement of two magnets 2 - 1 and 2 - 2 and two magnetic field sensors 11 - 1 and 11 - 2 is shown. Figure 13 This is a front view of the face of a person (living body 200) as viewed from the front.

[0117] like Figure 13 As shown, in the upper jaw 201 of the biological body 200, the magnet 2-1 is arranged on the first molar part, and the magnet 2-2 is arranged on the second molar part opposite to the first molar part. Specifically, each magnet 2-1, 2-1 is set on each tooth guard 211, and each tooth guard 211 is connected to Figure 2 The mouthpiece 211 shown is also attached to each molar portion of the upper jaw 201 of the living body 200. By attaching the mouthpiece 211 to each molar portion of the upper jaw 201 of the living body 200, each magnet 2-1, 2-1 is arranged on each two molar portions of the upper jaw 201 of the living body 200.

[0118] In addition, if Figure 13 As shown, magnet 2-1 and magnet 2-2 are configured to have opposite polarities. Figure 13 In the example, magnet 2-1 has an opening direction 300 as an N pole, and magnet 2-2 has an opening direction 300 as an S pole. As a result, the magnetic field in magnetic field sensor 11-1 and the magnetic field in magnetic field sensor 11-2 have opposite polarities.

[0119] In addition, if Figure 13 As shown, in the lower jaw 202 of the living body 200, the magnetic field sensor 11-1 is arranged at the first molar portion, and the magnetic field sensor 11-2 is arranged at the second molar portion on the opposite side of the first molar portion. Figure 2As shown, the main device 1 including the magnetic field sensor 11-1 is provided on a mouthpiece 212 (first mouthpiece), which is attached to the first molar portion of the lower jaw 202 of the living subject 200. By attaching the first mouthpiece 212 to the first molar portion of the lower jaw 202 of the living subject 200, the main device 1 is positioned at the first molar portion of the lower jaw 202 of the living subject 200. Thus, the magnetic field sensor 11-1 included in the main device 1 is positioned at the first molar portion of the lower jaw 202 of the living subject 200. The magnetic field sensor 11-2 is provided on a mouthpiece 212 (second mouthpiece), which is attached to the second molar portion of the lower jaw 202 of the living subject 200. By attaching the second mouthpiece 212 to the second molar portion of the lower jaw 202 of the living subject 200, the magnetic field sensor 11-2 is positioned at the second molar portion of the lower jaw 202 of the living subject 200.

[0120] exist Figure 13 In the example, the main device 1 including the magnetic field sensor 11-1 is disposed in the first molar portion of the lower jaw 202 of the living body 200. Therefore, in the lower jaw 202 of the living body 200, wiring is provided that connects the magnetic field sensor 11-2 and the main device 1 from the magnetic field sensor 11-2 disposed in the second molar portion to the main device 1 disposed in the first molar portion.

[0121] The signal processing unit 100 performs calculations to reduce the influence of geomagnetism from the magnetic field measured by the magnetic field sensor 11-1 based on the magnetic field measured by the magnetic field sensor 11-2. Figure 13 As shown, since magnets 2-1 and 2-2 are arranged with opposite polarities, the magnetic field in magnetic field sensor 11-1 and the magnetic field in magnetic field sensor 11-2 have opposite polarities. Therefore, if the magnetic field vector caused by magnet 2-1 in magnetic field sensor 11-1 is H_M, the magnetic field vector caused by magnet 2-2 in magnetic field sensor 11-2 is -H_M. Furthermore, if the geomagnetic vector is H_0, the influence of geomagnetism can be eliminated by subtracting the magnetic field vector "-H_M + H_0" measured by magnetic field sensor 11-2 from the magnetic field vector "H_M + H_0" measured by magnetic field sensor 11-1 using the following equation. This effectively doubles the sensitivity of the magnetic field generated by magnets 2 (2-1, 2-2). (H_M+H_0)-(-H_M+H_0)=2H_M

[0122] This can reduce the influence of geomagnetism and improve the sensitivity of the magnetic field, thereby enabling calculation of relative positions with higher accuracy.

[0123] According to the third embodiment, in addition to the same effects as those of the first embodiment, an effect of preventing a decrease in measurement accuracy by reducing the influence of geomagnetism on measurement can be obtained.

[0124] Alternatively, the third embodiment may be combined with the second embodiment described above. In this case, the main device includes a magnetic field sensor 11, a posture sensor 13, and a geomagnetic sensor 14. The signal processing unit 100 performs a correction for the tilt of the magnet 2 or the magnetic field sensor 11 based on the orientation 410 measured by the posture sensor 13 when calculating the relative position between the magnet 2 and the magnetic field sensor 11, and performs a calculation to reduce the influence of geomagnetism from the magnetic field vector measured by the magnetic field sensor 11 based on the geomagnetism measured by the geomagnetic sensor 14. Alternatively, the main device includes magnetic field sensors 11-1 and 11-2, and a posture sensor 13. The signal processing unit 100 performs a correction for the tilt of the magnet 2 or the magnetic field sensor 11 based on the orientation 410 measured by the posture sensor 13 when calculating the relative position between the magnet 2 (2-1, 2-2) and the magnetic field sensor 11 (11-1, 11-2), and performs a calculation to reduce the influence of geomagnetism from the magnetic field vector measured by each of the magnetic field sensors 11-1 and 11-2.

[0125] While the embodiments have been used to describe the methods for implementing the present invention, the present invention is by no means limited to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. The structures described in the above embodiments and examples may also be combined.

[0126] Industrial applicability According to the present invention, it is possible to easily measure the movement of a part of a living body.

[0127] Description of Reference Signs 1, 1a, 1b…Main unit of the biological motion measuring device, 2…Magnet of the biological motion measuring device, 10…Control unit, 11…Magnetic field sensor, 12…Battery, 13…Posture sensor, 14…Geomagnetic sensor, 100…Signal processing unit, 101…Storage unit, 102…Wireless communication unit, 103…Antenna, 104…RTC.

Claims

1. A biological motion measuring device, wherein: have: One or more magnetic generators disposed at a first location in the biological body; and One or more magnetic field sensors are arranged at other parts of the biological body different from the first part, and are used to measure the magnetic field generated by each magnetic generator using more than two orthogonal measurement axes.

2. The biological motion measuring device according to claim 1, wherein: The magnetic generator is a bipolar magnet.

3. The biological motion measuring device according to claim 1 or 2, wherein: The magnetic poles of the magnetic generator are arranged to face the movable directions of the first portion and the other portions.

4. The biological motion measuring device according to any one of claims 1 to 3, wherein: The magnetic flux density of the magnetic generator is above 300 millitesla.

5. The biological motion measuring device according to any one of claims 1 to 4, wherein: The magnetic field sensor is composed of any one or more combinations of a Hall sensor, a magnetoresistive effect sensor and a magnetoresistive impedance sensor.

6. The biological motion measuring device according to any one of claims 1 to 5, wherein: The plurality of magnetic field sensors are arranged at different distances from one magnetic generator.

7. The biological motion measuring device according to any one of claims 1 to 6, wherein: One or more posture sensors are further provided. The one or more posture sensors are arranged at at least one of the first part and the other part, and measure the orientation of the arranged part.

8. The biological motion measuring device according to claim 7, wherein: The posture sensor measures three-dimensional orientation.

9. The biological motion measuring device according to claim 7 or 8, wherein: The posture sensor is composed of a combination of any one or more of a gyro sensor, an acceleration sensor, and a geomagnetic sensor.

10. The biological motion measuring device according to any one of claims 1 to 9, wherein: It also comprises: a magnetic generator having a polarity opposite to that of the magnetic generator, arranged at the first portion; and An additional magnetic field sensor is arranged at the other location and is used to measure the magnetic field generated by the magnetic generator with opposite polarity using two or more orthogonal measurement axes.

11. The biological motion measuring device according to any one of claims 1 to 10, wherein: The first part is a part that moves in conjunction with either the upper jaw or the lower jaw of the organism, The other part is a part that moves in conjunction with another jaw, different from the first part, of the upper jaw and the lower jaw of the living body.

12. The biological motion measuring device according to any one of claims 1 to 11, wherein: The first part is either the upper jaw or the lower jaw in the oral cavity of the organism, The other part is another jaw, different from the first part, of the upper jaw and the lower jaw in the oral cavity of the living body.

13. The biological motion measuring device according to any one of claims 1 to 12, wherein: The first site and the other sites are molar sites.

14. The biological motion measuring device according to any one of claims 1 to 13, wherein: The magnetic generator is arranged on the mouthpiece installed on the first part, The magnetic field sensor is arranged on the mouthpiece installed on the other part.

15. The biological motion measuring device according to any one of claims 1 to 14, wherein: The magnetic generator is configured such that the magnetic pole faces the opening direction.

16. The biological motion measuring device according to any one of claims 1 to 14, wherein: The magnetic field sensor is disposed at a position where vectors of two or more components of the magnetic field generated by the magnetic generator change.

17. The biological motion measuring device according to any one of claims 7 to 14, wherein: The mouthguard installed at the other position is also provided with a posture sensor. The living body motion measurement device further includes a signal processing unit that measures the motion of the jaw of the living body with six degrees of freedom based on the magnetic field measured by each of the magnetic field sensors and the orientation measured by the posture sensor.

18. A biological motion measurement system, wherein: have: One or more magnetic generators are disposed at a first portion of the biological body; One or more magnetic field sensors, arranged at other parts of the biological body different from the first part, for measuring the magnetic field generated by each magnetic generator using two or more orthogonal measurement axes; as well as The signal processing unit calculates the relative position between each of the magnetic generators and each of the magnetic field sensors based on the magnetic field measured by each of the magnetic field sensors.

19. A biological motion measurement system, wherein: have: The biological motion measuring device according to any one of claims 7 to 17; and a signal processing unit that calculates the relative position between each magnetic generator and each magnetic field sensor based on the magnetic field measured by each magnetic field sensor, The signal processing unit performs correction related to the inclination of each magnetic generator or each magnetic field sensor generated during the movement of the living body based on the orientation measured by each posture sensor in the calculation of the relative position.

20. The biological motion measurement system according to claim 18 or 19, wherein: A geomagnetic sensor is also provided, the geomagnetic sensor measures the geomagnetism received by the magnetic field sensor, The signal processing unit reduces the influence of the geomagnetism from the magnetic field measured by the magnetic field sensor based on the geomagnetism measured by the geomagnetic sensor.

21. The biological motion measurement system according to any one of claims 18 to 20, wherein: The magnetism received by the plurality of magnetic field sensors is measured, and the tilt is corrected based on the relative coordinates of the plurality of magnetic sensors.

22. The biological motion measurement system according to any one of claims 18 to 21, wherein: The first part and the other parts are molar parts, A storage unit is further provided, the storage unit storing data indicating a positional relationship between a molar part and a front tooth part of the living body, The signal processing unit converts the calculation result of the relative position into the relative position between the front teeth of the upper jaw and the front teeth of the lower jaw of the living body based on the positional relationship.

23. The biological motion measurement system according to any one of claims 18 to 22, wherein: A conversion table is further provided, the conversion table being used to convert the magnetic field measured by the magnetic field sensor into the relative position, When acquiring the relative position from the magnetic field measured by each of the magnetic field sensors based on the conversion table, the signal processing unit supplements the insufficient position information in the conversion table through interpolation processing.

24. The biological motion measurement system according to claim 23, wherein: The interpolation process is linear interpolation or interpolation using a radial basis function.

25. The biological motion measurement system according to any one of claims 18 to 24, wherein: further comprising a storage unit storing a history showing a series of movements of the first part and the other parts of the living body, The signal processing unit calculates the relative position using the history.

26. The biological motion measurement system according to claim 23, wherein: The signal processing unit limits the range of the relative position referred to in the conversion table based on a previous calculation result of the relative position.

27. The biological motion measurement system according to any one of claims 18 to 26, wherein: The magnetic field sensor measures the magnetic field at a sampling rate of more than 100 Hz.

28. The biological motion measurement system according to claim 19, wherein: The magnetic field sensor measures the magnetic field at a sampling rate of more than 100 Hz. The posture sensor measures posture at a sampling rate of more than 20 Hz.

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