JP4310159B2 - Three-dimensional motion measuring apparatus and method - Google Patents

Description

The present invention relates to a three-dimensional motion measurement apparatus and method for measuring the three-dimensional motion of an object by detecting the position of a magnetic marker with a magnetic field sensor.

  2. Description of the Related Art Conventionally, apparatuses for measuring the three-dimensional motion of an object have been provided on the market. For example, a magnetic three-dimensional motion measurement device is used to measure the relative six-degree-of-freedom motion of the lower jaw with respect to the upper jaw configured integrally with the human head (see Patent Document 1). .

  In this measuring apparatus, a field coil is attached to the upper jaw of the person to be measured, and a center coil is attached to the lower jaw via an attachment member. In this case, when the measurement subject performs jaw movement in the state in which an alternating current is applied to the field coil to generate an alternating magnetic field, the movement of the lower jaw is transmitted to the center coil via the attachment member. Due to the movement of the lower jaw, an induction signal is output to the center coil. In this measuring apparatus, the relative position between the upper jaw and the lower jaw is detected using this guidance signal.

  However, in the measuring apparatus described above, since an alternating current is passed through the lead wire to the field coil that is a magnetic marker, the presence of this lead wire increases the discomfort of the subject. It is difficult to measure jaw movement in a natural state.

  As another three-dimensional motion measuring device, there is a three-dimensional motion measuring device 100 shown in FIGS. 14 and 15 (see cited document 2). The three-dimensional motion measuring apparatus 100 has a magnetic marker 16a attached to a forehead 32 that is considered to be integral with the upper jaw 22 of the person 14 to be measured, and a magnetic marker on the incisor of the lower jaw dentition as a representative point of the lower jaw 24. Attach 16b. The magnetic markers 16a and 16b are attached such that the magnetization direction J (magnetic dipole moment direction) faces the front of the face. A plurality of magnetic field sensors 20i (the number of magnetic markers × 5 or more) for detecting the magnetic fields of the magnetic markers 16a and 16b are arranged to face the magnetic markers 16a and 16b. Changes in the magnetic field of the magnetic markers 16a and 16b accompanying the jaw movement are detected by the magnetic field sensor 20i, the positions of the magnetic markers 16a and 16b from the fixed coordinates (absolute coordinate system X0Y0Z0) are detected, and the jaw movement is performed based on the jaw shape. It is displayed on the display 214.

JP 2000-193409 A JP 2002-355264 A

  In the conventional three-dimensional motion measuring apparatus 100, the y coordinate Y0 of the absolute coordinate system X0Y0Z0, the y coordinate Yu of the upper jaw coordinate system XuYuZu, and the y coordinate Yb of the lower jaw coordinate system XbYbZb are assumed to be Yu // Yb // Y0. However, it is possible to measure a six-degree-of-freedom motion only when the magnetization direction J and the x-coordinates X0, Xu, and Xb of the magnetic markers 16a and 16b are set to J // X0 // Xu // Xb. In other words, the three-dimensional motion measuring apparatus 100 is basically a motion measuring apparatus for a five-degree-of-freedom motion (motion represented by five coordinates of x, y, z, θ, and φ).

  By the way, when the relative movement between the upper jaw 22 and the lower jaw 24 is performed, the lower jaw 24 is in the temporomandibular joint portion with respect to the Ψ direction with the x coordinate X0, Xu, Xb (magnetization direction J) as the central axis. Perform 6-DOF motion including rotational motion.

  Since the above-described three-dimensional motion measuring apparatus 100 cannot measure a six-degree-of-freedom motion unless the condition of Yu // Yb // Y0 is satisfied, the three-dimensional motion measuring apparatus 100 performs the rotational motion in the Ψ direction. It cannot be measured.

  Therefore, for example, it is conceivable to measure a motion with 6 or more degrees of freedom by increasing the number of magnetic markers 16a and 16b and increasing the number of parameters (degrees of freedom) to be measured. However, in this method, since the number of parameters increases, the calculation time in the signal processing unit increases when the relative motion is calculated from the magnetic field detected by the magnetic field sensor 20i. The direction accuracy may be reduced.

  As described above, it is difficult for the three-dimensional motion measuring apparatus 100 to measure the six-degree-of-freedom motion including the rotational motion of the lower jaw 24 described above (motion including motion in the Ψ direction).

  Further, in the conventional three-dimensional motion measuring apparatus 100, the magnetic field of the magnetic marker 16a attached to the forehead 32 and the magnetic marker 16b attached to the lower jaw incisor is detected by the magnetic field sensor arrays 18a and 18b. In this case, since the magnetic field sensor arrays 18a and 18b are arranged so as to surround the front of the person to be measured 14, the magnetic field detected by each magnetic field sensor 20i is a magnetic field in which the magnetic fields of the magnetic markers 16a and 16b overlap each other. It is. For this reason, the magnetic field includes interference between the magnetic markers 16a and 16b and a difference in distance between the magnetic markers 16a and 16b and the magnetic field sensor 20i as errors. 100 measurement accuracy is reduced.

The present invention, by attaching to an object moving a magnetic generator, and to provide a three-dimensional movement measuring apparatus and method capable of measuring six degrees of freedom motion of the object.

The magnetic generator according to the present invention is a magnetic generator attached to the object when measuring the motion of the object, and each of the magnetic generators at a position where two magnetic markers are separated by a predetermined distance. the relative magnetic field generation direction of the magnetic marker it is characterized by comprising a fixing member for fixing to a known.

Further, the three-dimensional motion measuring apparatus according to the present invention provides each magnetic marker which is attached to the object and is a magnetic field generation source at a position separated from the two magnetic markers by a predetermined distance when measuring the motion of the object. And a magnetic generator having a fixing member for fixing the relative magnetic field generation direction to be known, and at least detecting a magnetic field generated from the magnetic marker in a non-contact manner for measuring a six-degree-of-freedom motion of the object. Six degrees of freedom information regarding the position and direction of the magnetic marker is obtained from six magnetic field sensors and the magnetic field detected by each of the magnetic field sensors, and the movement of the object is determined based on the obtained six degrees of freedom information and the shape of the object. signal processing means for calculating, it is characterized by comprising a.

  In the magnetic generator described above, the distance and relative direction between the magnetic markers are fixed by fixing the two magnetic markers to the fixing member using an adhesive or the like. Here, if the magnetic field directions of the two magnetic markers are known, by fixing the two magnetic markers with a fixing member, the magnetic field generation direction of the other magnetic marker itself with respect to the magnetic field generation direction of one magnetic marker itself The relative magnetic field generation direction of each magnetic marker is also known.

  The relative magnetic field generation direction of the two magnetic markers is a relative direction with respect to the magnetic field generation direction of the two magnetic generation sources themselves with respect to the two magnetic markers that are the magnetic generation sources. Specifically, when the magnetic marker is a magnetic material, it refers to a relative direction with respect to the magnetization directions (magnetization directions) of the two magnetic materials. When the magnetic marker is a coil, it refers to the relative direction with respect to the magnetic field generation direction of the two coils.

  When the object moves with six degrees of freedom with the magnetic generator configured as described above attached to the object, the distance between the magnetic markers does not change, but absolute coordinates (for example, the six magnetic fields) Since the coordinate position of the magnetic marker with respect to the coordinates of one of the sensors as a reference) changes, the surrounding magnetic field also changes.

  At this time, by detecting the magnetic field generated from the magnetic marker by at least six magnetic field sensors, the magnetic field detected by the six magnetic field sensors is described by the six coordinates, and the coordinate position of the magnetic marker is also determined. It is described by six coordinates (x, y, z, θ, φ, Ψ). That is, the 6-degree-of-freedom motion of the object can be measured with a three-dimensional motion measuring device only by fixing the distance and relative direction between the magnetic markers using the fixing member.

  If the fixing member is made of a non-magnetic material, the magnetic field detected by the magnetic field sensor is only the magnetic field generated from the magnetic marker. Thereby, the measurement accuracy of the magnetic field sensor can be improved.

The three-dimensional motion measurement apparatus according to the present invention is the magnetic field generation source at a position where the two magnetic markers are separated by a predetermined distance when measuring the relative motion of the first and second objects. First and second magnetic generators that include a fixing member that fixes the relative magnetic field generation direction of each magnetic marker to be known, and are attached to the first and second objects, and the first At least six first magnetic field sensors for detecting a magnetic field generated from the magnetic marker of the first magnetic generator in a non-contact manner for measuring the six-degree-of-freedom motion of the first object, and the second magnetic generator From the magnetic field detected by the first magnetic field sensor and at least six second magnetic field sensors that detect the magnetic field generated from the magnetic marker in a non-contact manner for measuring the six-degree-of-freedom motion of the second object, Magnetic marker position and direction First 6 degree-of-freedom information relating to the first and second degrees-of-freedom information relating to the position and direction of the magnetic marker from the magnetic field detected by the second magnetic field sensor. Signal processing means for calculating relative motions of the first and second objects based on the six degrees of freedom information and the shapes of the first and second objects. The

  This three-dimensional motion measuring device is a device that measures the six-degree-of-freedom motion of the first and second objects that perform relative motion. In this case, the first magnetic field sensor is disposed opposite to the first magnetic generator, and the second magnetic field sensor is disposed opposite to the second magnetic generator.

  That is, the magnetic field generated from the magnetic marker of the first magnetic generator is detected by the first magnetic field sensor, and the magnetic field generated from the magnetic marker of the second magnetic generator is detected by the second magnetic field sensor. Is done. Thereby, interference between the magnetic fields generated from the first and second magnetic generators is suppressed, and the measurement accuracy of the magnetic field detected by the first and second magnetic field sensors is improved. Thus, also for the first and second magnetic generators, the measurement accuracy can be improved by using a magnetic marker having a small generated magnetic field. That is, the first and second magnetic field generators can be reduced in size.

  If the fixing member is made of a non-magnetic material, the magnetic field detected by the magnetic field sensor is only the magnetic field generated from the magnetic marker. Thereby, the measurement accuracy of the magnetic field sensor can be further improved.

  Further, since the first and second magnetic field sensors are arranged apart from each other, the arrangement area of the first and second magnetic field sensors with respect to the magnetic marker can be expanded.

  Further, in the three-dimensional motion measuring apparatus, the first and second magnetic generators are attached to the first and second objects, respectively, with two magnetic markers fixed to a fixing member. Let the relative motion (6 DOF motion) of the two objects be performed.

  In this case, the distance and relative direction between the magnetic markers do not change, but the coordinate positions of the magnetic markers with respect to absolute coordinates change, and the surrounding magnetic field also changes. The magnetic field generated from the magnetic marker is detected by at least six first and second magnetic field sensors. Thereby, the magnetic field detected by the first and second magnetic field sensors is described by 6-degree-of-freedom information composed of 6 positions and directions, and the coordinate position of the magnetic marker is also determined from the 6 positions and directions. It is described by configured 6-degree-of-freedom information. That is, the six-degree-of-freedom motion of the first and second objects can be measured with a three-dimensional motion measuring device simply by fixing the fixing member with respect to the distance and relative direction between the magnetic markers.

Then, the magnetic generator described above, the fixed member may have preferably a shape corresponding to the mounting surface of the object. Thereby, since the distance of the said magnetic marker and the surface of the said object gets closer, the measurement precision of the 6 degree-of-freedom motion of the said object can be improved. In addition to this, there is an effect that the measurement subject is less uncomfortable.

  In addition, the shorter the distance between the magnetic markers, the smaller the restrictions on arrangement, but the position accuracy may deteriorate. Also, the greater the distance between the magnetic markers, the better the position accuracy, but the greater the constraints on arrangement. From the result of the preliminary experiment, when the distance between the magnetic field sensor and the magnetic generator is about 5 to 50 [mm], it is confirmed that the distance between the magnetic markers is preferably about 5 to 50 [mm]. When it is larger than 50 [mm], the measurement accuracy is lowered, and the magnetic generator is enlarged, resulting in an increase in discomfort for the measurement subject.

Then, the magnetic marker, it is not preferable is a magnetic generator or a permanent magnet with a coil. If the magnetic marker is a permanent magnet, a magnetic field can be generated from the permanent magnet, which eliminates the need to insert a lead wire or the like into the oral cavity of the person being measured, particularly reducing the burden on children and the elderly. Is done. In this case, the relative magnetic field generation direction in the two permanent magnets refers to the magnetization direction of the other permanent magnet with respect to the magnetization direction of one permanent magnet.

  On the other hand, when the magnetic marker is a magnetism generating means using a coil, the magnetism generating means is a small-sized one in which a power source (for example, a button-type battery), a power supply unit, and the coil are mounted on a circuit board. It is preferable to reduce the burden on the measurement subject as much as possible by using a magnetic generation circuit. In this case, the relative magnetic field generation direction in the two coils refers to the magnetic field generation direction of the other coil with respect to the magnetic field generation direction of one coil.

The object is a portion that moves integrally with the upper jaw of the skull of the measurement subject, or a portion that moves integrally with the lower jaw of the skull. Alternatively, the first object to which the first magnetic generator is attached is a portion of the skull of the measurement subject that moves integrally with the upper jaw, and the second magnetic generator is attached to the first object. the second object, among the cranial, Ru Ah at a portion integrally exercise and lower jaw. The first magnetic generator is attached to the forehead of the portion that moves integrally with the upper jaw, and the second magnetic generator is attached to the lower jaw of the portion that moves integrally with the lower jaw. attached to Ru.

Further, the magnetic field sensor, each of the magnetic field sensor is but it may also be configured as a magnetic field sensor arrays integrally.

In the three-dimensional motion measurement method according to the present invention, the two magnetic markers are fixed at a position separated by a predetermined distance so that the relative magnetic field generation directions of the magnetic markers as magnetic field generation sources are known. A mounting process for attaching a magnetic generator having a fixing member to a moving object, and a detection process for detecting the magnetic field of the magnetic marker in a non-contact manner by using at least six magnetic field sensors for measuring the six-degree-of-freedom movement of the object. And 6-degree-of-freedom information relating to the position and direction of the magnetic marker from the magnetic field detected by each magnetic field sensor, and calculating the motion of the object based on the obtained 6-degree-of-freedom information and the shape of the object and process, that are characterized by comprising a.

  In this measurement method, the magnetic generator is configured by fixing the distance between the two magnetic markers with the fixing member, and the object is moved with six degrees of freedom while the magnetic generator is attached to the object. Make it. In this case, the distance and relative direction between the magnetic markers are not changed by the fixing member, but the coordinate positions of the magnetic markers with respect to the absolute coordinates are changed.

  At that time, since the magnetic field generated from the magnetic marker is detected by at least six magnetic field sensors, the magnetic fields detected by the six magnetic field sensors are described in six positions and directions (six degrees of freedom information), respectively. At the same time, the coordinate position of the magnetic marker is also described in six positions and directions (information on six degrees of freedom). Therefore, it is possible to easily measure the six-degree-of-freedom motion of the object simply by fixing the distance and relative direction between the magnetic markers with the fixing member.

  Also in this measurement direction, if the directions of the magnetic fields of the two magnetic markers are known, the two magnetic markers are fixed by a fixing member, so that The direction of the magnetic field (relative magnetic field generation direction) is also known.

  If the fixing member is made of a non-magnetic material, the magnetic field detected by the magnetic field sensor is only the magnetic field generated from the magnetic marker. Thereby, the measurement accuracy of the magnetic field sensor can be further improved.

In the three-dimensional motion measurement method according to the present invention, the two magnetic markers are fixed at a position separated by a predetermined distance so that the relative magnetic field generation directions of the magnetic markers as magnetic field generation sources are known. The first and second magnetic generators having the fixing members are attached to the relatively moving first and second objects, respectively, and generated from the magnetic marker of the first magnetic generator. A magnetic field is detected in a non-contact manner by at least six first magnetic field sensors, and a magnetic field generated from the magnetic marker of the second magnetic generator is used for measuring a six-degree-of-freedom motion of the first object. The position of the magnetic marker is determined based on a detection process in which the second object is detected in a non-contact manner using at least six second magnetic field sensors, and a magnetic field detected by the first magnetic field sensor. First 6 degree-of-freedom information related to the direction of the magnetic marker, and second 6-degree-of-freedom information related to the position and direction of the magnetic marker from the magnetic field detected by the second magnetic field sensor. And a signal processing step of calculating relative movements of the first and second objects based on second six-degree-of-freedom information and the shapes of the first and second objects. The

  This three-dimensional motion measurement method is a method for measuring the six-degree-of-freedom motion of the first and second objects that perform relative motion. In this case, the first magnetic field sensor is disposed opposite to the first magnetic generator, and the second magnetic field sensor is disposed opposite to the second magnetic generator. The generated magnetic field is measured. That is, the magnetic field generated from the magnetic marker of the first magnetic generator is detected by the first magnetic field sensor, and the magnetic field generated from the magnetic marker of the second magnetic generator is detected by the second magnetic field sensor. Is done. Thereby, interference between the magnetic fields generated from the first and second magnetic generators is suppressed, and the measurement accuracy of the magnetic field detected by the first and second magnetic field sensors is improved. Thus, also for the first and second magnetic generators, the measurement accuracy can be improved by using a magnetic marker having a small generated magnetic field. That is, the first and second magnetic field generators can be reduced in size.

  Further, since the first and second magnetic field sensors are arranged apart from each other, the arrangement area of the first and second magnetic field sensors with respect to the magnetic marker can be expanded.

  If the fixing member is made of a non-magnetic material, the magnetic field detected by the first and second magnetic field sensors is only the magnetic field generated from the magnetic marker. Thereby, the measurement accuracy of the first and second magnetic field sensors can be further improved.

  Also in this measurement method, the distance and relative direction of the magnetic marker are not changed by the fixing member, but the coordinate position of each magnetic marker with respect to the absolute coordinate is changed. In this case, since the magnetic field generated from the magnetic marker is detected by at least six first and second magnetic field sensors, the magnetic field detected by the six magnetic field sensors has six positions and directions (six free positions). Degree information), and the coordinate position of the magnetic marker is also described in six positions and directions (six degree of freedom information). As a result, the relative movement (6-degree-of-freedom movement) of the first and second objects can be easily measured simply by fixing the distance and relative direction of the magnetic marker with the fixing member.

  Also in this measurement direction, if the directions of the magnetic fields of the two magnetic markers are known, the two magnetic markers are fixed by a fixing member, so that The direction of the magnetic field (relative magnetic field generation direction) is also known.

In each of the measurement methods described above, the (first and second) objects are a part of the subject's skull that moves integrally with the upper jaw, or a part of the skull that is integrated with the lower jaw. It is the part that moves. Also, at least two objects to the relatively motion, the out of the skull of the subject, the upper and portion which integrally motion, Ru part and der that moves integrally with the lower jaw.

The engaging Ru 3-dimensional movement measuring apparatus and method of the present invention, the two magnetic markers is fixed to the fixing member by a magnetic generator, so attached to a moving object of the magnetic generator, 6 free of the object Can be measured easily.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings of FIGS. In addition, in order to avoid that drawing becomes complicated, the external appearance, jaw shape, tooth shape, etc. of to-be-measured person 14 are drawn deformed in drawing. Further, the same components as those of the conventional three-dimensional motion measuring apparatus 100 shown in FIGS. 14 and 15 will be described with the same reference numerals.

  FIG. 1 shows an overall configuration of a three-dimensional jaw movement measuring system 10 including a three-dimensional jaw movement measuring apparatus and a three-dimensional position detecting apparatus to which an embodiment of the present invention is applied.

  FIG. 2 schematically shows an enlarged configuration in which a part of the three-dimensional jaw movement measurement system 10 of FIG. 1 is brought close to the person to be measured 14.

  FIG. 3 shows an electric circuit block diagram of the three-dimensional jaw movement measuring system 10 of FIG.

  FIG. 4 shows an enlarged configuration of the magnetic generator 15 used in the three-dimensional jaw movement measurement system 10.

As shown in FIGS. 1 to 3, the three-dimensional jaw movement measuring system 10 basically fixes magnetic markers 16 a to 16 d such as permanent magnets to a fixing member 13, and this fixing member 13 is measured. Magnetic field detector 15 (15a, 15b) (see FIG. 4) attached to a predetermined position of 14 with an adhesive or the like, and the magnetic field of each of magnetic markers 16a-16d for 6-DOF motion measurement without contact, respectively Magnetic field sensor arrays (also simply referred to as magnetic field sensors) 18a (a = 1 to 4) and 18b (b = 1 to 6), and magnetic field sensors 20i constituting the magnetic field sensor array 18 (18a and 18b). (As shown in FIGS. 2 and 3, in this embodiment, a total of 62 magnetic fields including magnetic field sensors 20i (i = _{1 to 62} ), magnetic field sensors 20 _{1 to} 20 ₂₀ and magnetic field sensors 20 _{21 to} 20 62 are provided. Sensor) From the magnetic field, the positions and directions of the magnetic markers 16a to 16d are obtained, and based on the obtained positions and directions of the magnetic markers 16a to 16d and the shapes of the upper jaw 22 and the lower jaw (mandible) 24 that are rigid bodies, the upper jaw 22 And a personal computer (PC) 26 as signal processing means for calculating in real time 6-degree-of-freedom movement of the lower jaw 24.

  Since the magnetic field sensor arrays 18a and 18b are configured as a magnetic field sensor assembly in which the individual magnetic field sensors 20i are integrated, the relative position between the individual magnetic field sensors 20i is a known position in the personal computer 26. You can remember it. As shown in FIGS. 1 and 2, the four magnetic field sensor arrays 18a each contain five magnetic field sensors 20i, and the six magnetic field sensor arrays 18b each contain seven magnetic field sensors 20i.

  As shown in FIGS. 1 and 3, the personal computer 26 includes a main body 50 as signal processing means having a CPU, ROM, RAM, hard disk, etc. (not shown), and a monitor such as a CRT display connected to the main body 50. It has a display 52, a keyboard 54 that functions as input means connected to the main body 50, and a mouse 56, and is housed on an upper shelf of a rack 46 that can be fixed and moved by a caster 45.

  In addition to the personal computer 26, the rack 46 houses a printer 60, an AD converter 62, and a power supply unit 64.

  In the rack 46 in which the personal computer 26 and the like are arranged, magnetic markers 16a to 16d of the magnetic generator 15 attached to the measurement subject 14, a magnetic field sensor array 18, and an external magnetic field detection sensor 44 described later are arranged. It is arranged via wiring 66 so as to be away from the measuring stand 38 so as not to exert a magnetic interaction. As the wiring 66, a multi-core electric wire with an electromagnetic shield coating is used.

  As shown in FIG. 3, the power supply unit 64 is connected to an AC power supply such as AC 100 V (not shown) via a power cord 80, and the DC power generated by the power supply unit 64 is supplied to the AD converter 62. At the same time, it is supplied to the magnetic field sensor arrays 18a and 18b and the external magnetic field detection sensor 44 via the wiring 66b.

  As shown in FIG. 1, a pointer holder 74 is fixed on the lower shelf of the rack 46, and a measurer (not shown) or the like can be arbitrarily moved by the measurer (not shown). A free pointer 70 having a magnetic marker 72 therein is inserted in a freely removable state.

  As shown in FIGS. 2 and 3, the pointer 70 is a pencil-shaped rod having a magnetic marker 72 that is a magnet and having a substantially conical pointed tip 76. The material other than the magnetic marker 72 built in the pointer 70 is a non-magnetic material such as resin. In this case, the distance between the position of the substantially conical tip 76 of the pointer 70 and the magnetic marker 72 (the center thereof) is known, and is stored and stored in the hard disk of the main body 50. Further, the magnetic marker 72 is attached so that the magnetization direction of the magnetic marker 72 coincides with the axial direction of the pointer 70. In order to minimize the measurement error, the built-in magnetic marker 72 is preferably arranged and fixed as close to the tip 76 as possible. Of course, it can also be arranged at the tip 76.

  4A, the magnetic generator 15 is configured by attaching two magnetic markers 16 to the upper surface of a fixed member 13 that is a rigid body with an adhesive or the like. Thereby, the distance d between the two magnetic markers 16 becomes a known distance fixed by the fixing member 13.

  Further, if the magnetic field directions of the two magnetic markers 16 are known in advance, the two magnetic markers 16 are fixed by the fixing member 13, so that The direction of the magnetic field (hereinafter referred to as a relative magnetic field generation direction) is also known.

  The relative magnetic field generation direction of the two magnetic markers 16 is a relative direction with respect to the magnetic field generation directions of the two magnetic generation sources themselves with respect to the two magnetic markers 16 that are the magnetic generation sources. Specifically, when the magnetic marker 16 is a magnetic body, it refers to a relative direction with respect to the magnetization directions (magnetization directions) J of the two magnetic bodies. Further, when the magnetic marker 16 is a coil, it refers to a relative direction with respect to the magnetic field generation direction of the two coils.

  Here, it is preferable that the fixing member 13 is formed of a non-magnetic material such as an acrylic resin. Further, as the distance d between the two magnetic markers 16 is shorter, the arrangement restriction is smaller, but the positional accuracy may be deteriorated. Also, the greater the distance d, the better the position accuracy, but the greater the constraints on the arrangement. From the result of the preliminary experiment, when the distance between the magnetic field sensor 20i and the magnetic generators 15a and 15b is about 5 to 50 [mm], it is confirmed that d is preferably about 5 to 50 [mm]. Yes. When the distance d is smaller than 5 [mm], magnetic field interference occurs between the magnetic markers 16a to 16d. On the other hand, when the distance d is larger than 50 [mm], the measurement accuracy of the magnetic field sensor 20i is lowered, the magnetic generator 15 is enlarged, and the discomfort of the measurement subject 14 is increased.

  If the fixing member 13 is made of a non-magnetic material, the magnetic field detected by the magnetic field sensor 20i is only the magnetic field generated from the magnetic markers 16a to 16d. Thereby, the measurement accuracy of the magnetic field sensor 20i can be further improved.

  1 to 4, the magnetic generator 15 can be easily applied to the crown portion of the lower incisor among the forehead 32 and the lower teeth (lower dentition) 34 of the measurement subject 14 sitting on the chair 30. Are attached via removable adhesives or the like.

  At this time, as shown in FIG. 4B, the shape of the fixing member 13 may be a shape along (corresponding to) the forehead 32 that is the mounting surface of the object (the person 14 to be measured) and the crown portion. Thereby, since the distance between the magnetic markers 16a to 16d, the forehead 32, and the crown portion is closer, the measurement accuracy of the six-degree-of-freedom movement of the upper jaw 22 and the lower jaw 24 can be improved. In addition to this, for example, when the magnetic generator 15b is attached to the crown portion of the person to be measured 14, an effect that the feeling of discomfort of the person to be measured 14 is small can be obtained. In this case, the distance d may be a linear distance connecting the central portion of the magnetic marker 16a (16c) and the central portion of the magnetic marker 16b (16d).

  In this embodiment, the magnetic marker 16 and the magnetic marker 72 have a size of about 1 [mm] × 1 [mm] × 0.5 [mm] (thickness) and a saturation magnetic flux density of 1 [T (Tesla). A permanent magnet of a sintered magnet made of NdFeB (neodymium iron boron) material having a large maximum energy product is used. By using such magnetic markers 16 and 72, the magnetic field sensor 20i can detect a magnetic field of about 0.1 [mG (milli gauss)] to 100 [mG]. In FIG. 3, the magnetization direction (magnetization direction) J of the magnetic marker 16 is directed outward from the measurement subject 14, and the magnetic field detection direction of the magnetic field sensor 20 i coincides with the magnetization direction J. Is set to In this case, the relative magnetic field generation direction between the two magnetic markers 16 is the magnetization direction J of the other magnetic marker with respect to the magnetization direction J of one magnetic marker 16.

  In addition, you may comprise the magnetic marker 16 and the magnetic marker 72 by the magnetic generation means containing a coil. In this case, in order to reduce the burden on the subject 14 as much as possible, a power source (for example, a button-type battery), a power supply unit that supplies power from the power source to the coil, and the coil are provided. It is desirable to make it a small magnetism generating circuit configured to be mounted on a circuit board. In this case, the relative magnetic field generation direction between the two coils is the magnetic field generation direction of the other coil with respect to the magnetic field generation direction of one coil.

  Further, as will be described later, in the three-dimensional jaw movement measuring system 10, the three-dimensional jaw movement can be measured without matching the magnetization direction J of the magnetic marker 16 and the magnetic field detection direction of the magnetic field sensor 20i. . Further, the magnetization directions J of the magnetic markers 16a to 16d do not have to coincide with each other.

  As the magnetic field sensor 20i and the external magnetic field detection sensor 44, one using a Hall element, one using a magnetoresistive effect element, one using a high frequency carrier type thin film magnetic field sensor (Magneto Impedance Sensor), or having a high frequency excitation coil A well-known magnetic field sensor having one axis, two axes, or three axes such as a fluxgate sensor can be used.

  In particular, when a high frequency carrier type thin film magnetic field sensor is used, the size of the head is 1 [mm] or less, and the detection sensitivity of the high frequency carrier thin film magnetic field sensor of 1 [mm] or less is 10 [mm]. mm] about the same or higher sensitivity than the fluxgate sensor.

  Regarding the measurement of jaw movement, when using a high-frequency carrier type thin film magnetic field sensor, it is possible to consider the head size as a point, and when using a fluxgate sensor, the head size is considered to be finite if necessary. Process.

  That is, it is preferable to employ a magnetic field sensor 20i having a head size as small as possible. This is because the magnetic field around the magnetic marker 16 can be measured more accurately as the head size is smaller, and the detection position accuracy of the plurality of magnetic markers 16 is improved.

  As shown in FIG. 1, a headrest 29 that supports the head of the person to be measured 14 is attached to the backrest portion of the chair 30 on which the person to be measured 14 sits. The headrest 29 can be moved up and down, left and right, and forward and backward so that the position of the magnetic field sensor 20 i is as close as possible to the jaw of each person to be measured 14 and corresponding to the position of the head of the person to be measured 14. It has a possible configuration.

  As shown in FIG. 2, at the time of measurement in which the magnetic field sensor 20i is placed close to the measurement subject 14, the magnetic field sensor 20i is disposed so as to surround each of the magnetic markers 16a to 16d from the front of the face. Magnetic field sensor arrays 18 a and 18 b as magnetic field sensor assemblies composed of 20 i are attached to a sensor holder 36. The magnetic field sensor array 18 a is formed in an arc shape of 90 ° or more in the vertical direction so as to surround the forehead 32, and the magnetic field sensor array 18 b is formed in a substantially arc shape in the lateral direction so as to surround the lower jaw 24.

  As shown in FIG. 1, the sensor holder 36 to which the magnetic field sensor arrays 18a and 18b are attached can be adjusted between the columns 40 of the measurement stand 38 that can be adjusted to a free position in the vertical direction (vertical direction) by a fixing screw 41. Is attached. Each strut 40 is vertically attached to both ends of a substantially U-shaped base 42 in order to avoid the legs of the person 14 to be measured, and the measurement stand 38 having such a configuration is attached to the floor side of the base 42. The four casters 43 are movable and fixed in the direction of the person to be measured 14.

  Further, between the support columns 40, an external magnetic field detection sensor 44, which is a three-dimensional magnetic field sensor for detecting an external magnetic field (external unnecessary magnetic field) such as geomagnetism, is attached to the mounting holes 39 (39a, 39b, 39c, 39d) and the U-shaped. The arrangement is fixed via a frame 37. The external magnetic field detection sensor 44 can be arranged and fixed at any position of the mounting portions 39a, 39b, 39c, and 39d with a screw 35.

  The optimum arrangement position of the external magnetic field detection sensor 44 is a position where the magnetic field acting from the magnetic marker 16 is small enough to be ignored (basically, a position relatively distant from the magnetic marker 16), and each It is a position where a magnetic field equivalent to an external magnetic field including geomagnetism other than the magnetic marker 16 acting on the magnetic field sensor 20i can be detected with the three-axis component.

  The external magnetic field detection sensor 44 is arranged to cancel out the in-phase component of each magnetic field sensor 20i. In order to cancel out the fluctuation (fluctuation) magnetic field component in the external magnetic field component including the geomagnetism (DC magnetic field component + fluctuating magnetic field component), the magnetic field from the magnetic marker 16 causes the noise level of the magnetic field sensor 20i (in this case, 0.1). [MG: milligauss]) A position that is equal to or less is preferable.

  In this embodiment, as shown in FIG. 1, the pipe of the sensor holder 36 in which the external magnetic field detection sensor 44 is formed integrally with the magnetic field sensor array 18 having the magnetic field sensor 20i via the frame 37. It is designed to be fixed integrally to the part. For this reason, even if the support 40 is moved up and down and the sensor holder 36 is moved up and down so that the position of the magnetic field sensor array 18 corresponds to each individual person 14 to be measured, the space between the magnetic field sensor 20 i and the external magnetic field detection sensor 44 The positional relationship does not change. Due to this configuration, in each of the attachment portions 39a to 39d, the offset relationship between the output of each magnetic field sensor 20i and the output of the external magnetic field detection sensor 44 is once adjusted and determined and stored in the hard disk or the like of the personal computer 26. If this is done, there is the advantage that readjustment of this offset relationship becomes unnecessary.

  1 is preferably a non-magnetic material such as plastic resin, wood, aluminum, or stainless steel so as not to disturb the magnetic field from the magnetic marker 16 or the external magnetic field. Similarly, the sensor holder 36, the frame 37, and the screw 35 are preferably made of a nonmagnetic material.

  As shown in FIGS. 1 and 3, the magnetic field detected by each magnetic field sensor 20 i and the external magnetic field detection sensor 44 is supplied as an analog signal to an AD converter (analog-digital converter) 62 via a wiring 66. The AD converter 62 converts it into a value of magnetic field strength as digital data, and stores it in a predetermined area of the RAM and hard disk in the main body 50 constituting the personal computer 26.

  As described above, the main body 50 of the personal computer 26 functions as a signal processing unit. This signal processing unit is based on a pre-recorded application program and repeats calculations such as a maximum likelihood method as described later. Is used to calculate the positions of the magnetic markers 16a to 16d in real time from the digital data of the magnetic field strength supplied via the AD converter 62, and to determine the magnitude and direction of the external magnetic field based on the output of the external magnetic field detection sensor 44. In addition, when necessary, the position of the contact part at the tip of the movable pointer 70 having the magnetic marker 72 inside is calculated. The signal processing means stores and registers the position of the contact portion at the tip of the pointer 70 as a relative position with the magnetic marker 16 as a reference, and performs processing of reading out when necessary.

  In this way, the three-dimensional positions of the magnetic markers 16a to 16d and the like are measured. The main body 50 stores the measured positions of the magnetic markers 16a to 16d and the like in the RAM and the hard disk, and on the monitor display 52, based on these positions, the jaw movement image of the person corresponding to the person 14 to be measured is animated. As real time display.

  The three-dimensional jaw movement measurement system 10 according to this embodiment is basically configured and operates as described above. Next, the operation will be further described with reference to the operation flowchart shown in FIG. This will be described in detail.

  First, in step S1, the output value of each magnetic field sensor 20i is calibrated with the output value of the external magnetic field detection sensor 44, so-called calibration. This calibration is performed in a magnetic shielded specific facility in the factory of the manufacturer (manufacturer) of the three-dimensional jaw movement measurement system 10.

  That is, an equal magnetic field (a magnetic field equivalent to geomagnetism) is simultaneously applied to the external magnetic field detection sensor 44 and each magnetic field sensor 20i, for example, sequentially in the order of the three orthogonal axes X, Y, and Z. The relationship between the external magnetic field detection sensor 44 and the output value of each magnetic field sensor 20i (for example, the difference between the output of the external magnetic field detection sensor 44 and each magnetic field sensor 20i), and the output value of each magnetic field sensor 20i is 0 Alternatively, a correction coefficient that is small enough to be ignored is determined, and a lookup table (referred to as a lookup table (table) for external unnecessary magnetic field cancellation (calibration)) is created. This lookup table is stored in a hard disk that is a storage medium in the main body 50 of the personal computer 26. Instead of the lookup table, it can be stored as a calculation formula (calculation formula for canceling external unnecessary magnetic field (calibration)).

That is, in the lookup table (calibration table or calibration table) or calculation formula (calibration calculation formula), the detection magnetic field (vector) of each equal magnetic field by the external magnetic field detection sensor 44 is Bre, and each magnetic field sensor of each equal magnetic field. When the detected magnetic field (vector) by 20i (i is the i-th meaning) is Bmei, the correction coefficient k is set so that the value of the following equation (1) is 0 or the minimum value, and the detected magnetic field Bre is It is determined as a function to be a variable.
Bmei-kBre (1)

  After calibration at this manufacturer or the like, the three-dimensional jaw movement measurement system 10 is delivered to a measurement place such as a hospital, a clinic, or a health center.

  Next, in step S2, when the power is supplied to the three-dimensional jaw movement measurement system 10 at the measurement location as shown in FIG. 1, the output of the magnetic field sensor 20 is output from the external magnetic field detection sensor 44 at the measurement location. Is automatically calibrated. That is, the correction coefficient k, which is the subtraction ratio of the external magnetic field such as the geomagnetism detected by the external magnetic field detection sensor 44 at the measurement location, is based on the external magnetic field (vector) Br at the measurement location, and the calibration table. Alternatively, it is automatically calculated from a calibration formula.

  Thus, the reason why the output of the magnetic field sensor 20 is corrected by the output of the external magnetic field detection sensor 44 at the actual measurement location is because the external magnetic field such as geomagnetism changes in a non-constant manner with the passage of time or location.

  Therefore, according to the three-dimensional jaw movement measurement system 10 having the external magnetic field detection sensor 44, even if an external magnetic field such as geomagnetism changes during measurement, such variable noise components are automatically removed. Is done.

  It should be noted that the magnetic generators 15a and 15b are not attached to the measurement subject 14 when the power is turned on at the measurement location. Further, the magnetic generators 15a and 15b are placed at positions sufficiently away from each other so as not to affect the magnetic field sensor array 18 and the external magnetic field detection sensor 44 or in a magnetic shield box (not shown).

  Next, in step S <b> 3, the magnetic field sensor 20 i is arranged by disposing the measurement stand 38 against the measurement subject 14 sitting on the chair 30.

  In this case, the measurement stand 38 is moved closer to the person 14 to be measured from the position shown in FIG. 1, and the sensor holder 36 of the magnetic field sensor array 18 is moved to a predetermined position, for example, as seen from the side as shown in FIG. The caster 43 of the measurement stand 38 is fixed so that the tip of the holder 36 on the measured person 14 side is substantially coincident with the front surface of the measured person 14 face.

  In this step S3, the magnetic field sensor array 18 is further arranged and adjusted to a predetermined height with respect to the person 14 to be measured. Specifically, for example, among the lower teeth of the lower jaw (mandible) 24 of the person 14 to be measured, the position of the two central incisors Ti (the position where the magnetism generator 15b will be attached later) and the lower magnetic field sensor The sensor holder 36 is moved up and down so that the height of the array 18b matches, and the sensor holder 36 is fixed to the support column 40 with the fixing screw 41 in the matched state.

  FIG. 7 shows a state in which the measurement stand 38, in other words, the magnetic field sensor 20 i is arranged for the person to be measured 14. The width L2 (see FIG. 1) of the measurement stand 38 is wider than the lateral width L3 of the chair 30 which is set to a distance exceeding the distance between the upper arms, which is the maximum width of the person 14 to be measured. The sensor holder 36 having the sensor 20 i can be arranged at a desired position with respect to the person to be measured 14.

  In this case, since the position in the height direction of the external magnetic field detection sensor 44 is set to be above the arm placed on the thigh of the measurement subject 14, the external magnetic field detection sensor 44 does not contact the measurement subject 14.

  Furthermore, since the headrest 29 is disposed on the back head of the person 14 to be measured, the person 14 to be measured can naturally support his / her head without being compressed by the headrest 29, and the headrest 29 can be moved up and down. Since it can move left and right and back and forth, the mounting position of the magnetic marker 16 can be as close to the magnetic field sensor array 18 as possible.

  Thus, during measurement, the person under measurement 14 is in a state where only a very small magnetic generator 15 is attached, in other words, in a very free state without direct physical compression, as will be described later. It is possible to have jaw movement measurements or examinations. As shown in FIGS. 6 and 7, during this measurement, the field of view of the person to be measured 14 is hardly limited by the measuring device.

  Therefore, by using the three-dimensional jaw movement measuring system 10 according to this embodiment, the inconvenience of fixing the head of the person to be measured by the belt-fixed magnetic field sensor assembly or the light source device is eliminated. Therefore, it can be applied to children and elderly people who have been difficult with conventional devices.

  Next, in step S4, a frame in which the external magnetic field detection sensor 44 is attached by removing the screws 35 in a state where the magnetic field sensor array 18 is disposed opposite to the face of the measurement subject 14 as shown in FIG. By moving up and down 37, the optimum height of the external magnetic field detection sensor 44 at the measurement position is determined so that the value of the above equation (1) becomes the minimum value, and the position closest to the determined height position is determined. A frame 37, that is, an external magnetic field detection sensor 44 is attached and fixed to a certain attachment hole 39 with a screw 35.

During the measurement by the three-dimensional jaw movement measuring system 10, the calculation performed in the main body 50 of the personal computer 26 in relation to the external magnetic field detection sensor 44 is performed before the calibration of each magnetic field sensor 20 i (i is the i-th meaning). The output value (measurement magnetic field: vector) is Bmi0, the detection magnetic field (vector) by the external magnetic field detection sensor 44 is Br, the constant based on the correction table or the correction equation is k, and the measurement magnetic field of each magnetic field sensor 20i after correction is If Bmi is used, the measured magnetic field (vector) Bmi can be expressed by the following equation (2).
Bmi = Bmi0−kBr (2)

  It can be seen from this equation (2) that the time-varying noise of the external magnetic field can be removed.

During this measurement, the magnetic field sensor 20i having at least six components (six axis components) is arranged for one of the magnetic generators 15a and 15b attached to the measurement subject 14. That is, for the magnetic markers 16a and 16b constituting the magnetic generator 15a, the magnetic field sensors 20 _{1 to} 20 ₆ are arranged in the magnetic field sensor array 18a, and the magnetic markers 16c and 16d constituting the magnetic generator 15b are arranged. Thus, the magnetic field sensors 20 _{21 to} 20 ₂₇ are arranged in the magnetic field sensor array 18b. In this way, jaw movement with 6 degrees of freedom (x, y, z, θ, φ, Ψ) can be observed.

  However, as shown in FIG. 8, the angle φ and the angle θ are the inclination (direction angle) φ from the z axis of the vector P determined by the coordinates (x, y, z) from the origin O, and the vector P as xy. It represents the inclination (direction angle) θ from the x-axis when projected onto a plane. Further, as shown in FIG. 9, the angle ψ indicates a rotation angle ψ with the magnetization direction J of the magnetic markers 16 a to 16 d as a central axis.

  Next, in step S5, the magnetic generators 15a and 15b are arranged and the upper and lower jaw feature points are marked. In the measurement place shown in FIG. 1, in the process of steps S <b> 2 to S <b> 4, the magnetic generators 15 a and 15 b are actually not attached to the measurement subject 14.

  Here, the marking processing of the feature points of the upper and lower jaws is an arbitrary point on the surface of the upper jaw 22 or the lower jaw 24, for example, the lower right first molar central fovea point in the lower jaw 24, the point near the left and right lower jaw head, etc. Are set as relative coordinates with respect to the magnetic generator 15b.

  More specifically, the marking process of the feature points on the upper and lower jaws is a relative position of an arbitrary point on the upper and lower jaws with respect to the positions of the magnetic markers 16a to 16d in the magnetic generators 15a and 15b attached to the jaw of the measurement subject 14. This is a process of recognizing and registering (storing) (relative three-dimensional position).

  Therefore, first, in step S5a, two central incisors among the lower jaw teeth in the lower jaw (mandible) 24 of the measurement subject 14 as shown in FIG. A magnetic generator 15b taken out from the above-described magnetic shield box or the like is attached to the center of the crowns over Ti. The teeth are attached to the teeth because the teeth are hard tissue and are considered to be almost integral with the mandible. Therefore, the movement of the lower jaw 24 can be accurately performed by attaching to the teeth compared to the case where the teeth are attached to the soft tissue such as the lower lip. This is because it can be reproduced.

  Next, in step S5b, in order to set an arbitrary point (desired point, feature point, or representative point) of the lower jaw, the measurer or the like removes the pointer 70 from the pointer holder 74 of the rack 46, and the tip of the pointer 70 76 is brought into contact with a predetermined position in the lower dentition, for example, the foveal fovea of the second molar Tm (see FIG. 6), and the second molar Tm with respect to the position of the attached magnetic generator 15b is used as a reference. A three-dimensional coordinate position with respect to the occlusal surface fovea is obtained by a maximum likelihood method, which will be described later, from the output of the magnetic field sensor 20i of the magnetic field sensor array 18b.

  Actually, when the distal end portion 76 of the pointer 70 is in contact with the central fossa of the second molar tooth Tm of the person 14 to be measured, the mouse 56 that is an input device follows the display on the monitor display 52 according to the display on the monitor display 52. The position of the magnetic marker 72 inside the pointer is obtained from the magnetic field of the magnetic field sensor 20i at that time, for example, by clicking on the position of the screen, for example, a position displayed as “touching the pointer with the magnetic marker” on the screen. The position of the front end portion 76 of 70 is obtained. The position of the distal end portion 76 is the position of the central fovea of the occlusal surface of the second molar tooth Tm.

  In this way, the relative position of the occlusal fovea of the left and right second molar teeth Tm in the lower dentition relative to the magnetic generator 15b attached across the central incisor Ti is obtained, and the main body of the personal computer 26 is obtained. 50 is stored in the hard disk and registered. In the same procedure, other characteristic points of the mandible 24, for example, several points such as a mandibular left and right first molar fovea and a point near the left and right mandibular heads are marked, and the relative position with respect to the position of the magnetic generator 15b is stored. As a result of the registration, it is possible to measure the movements of the marked points simultaneously with the movement of the magnetic generator 15b.

  It should be noted that the subject 14 must move the head and jaw while marking an arbitrary point of the lower jaw 24 (feature point, for example, the point of the lower left and right first molar fovea and the point near the left and right lower jaw head). The magnetic markers 16c and 16d are not required, and any point of the lower jaw 24 can be marked only by the pointer 70. However, when the magnetic generator 15b is attached, the tip 76 of the pointer 70 is attached. Even when the head or jaw moves when it is brought into contact with the person 14 to be measured, the relative position of the attached magnetic generator 15b with respect to the magnetic markers 16c and 16d can be stored. It is possible to accurately mark an arbitrary point.

  In the marking of the lower jaw arbitrary point by the pointer 70 (relative position grasping), the coordinate position is stored and registered as the desired point by bringing the tip 76 of the pointer 70 into contact with the desired point, and therefore, the measurement target is measured. Only the points on the surface of the person 14 can register the coordinate position.

  However, in practice, it is necessary to measure the movement of the point inside the person to be measured 14, and in such a case, the position can be calculated by the personal computer 26 and registered. For example, a point in the vicinity of the left and right mandibular head (slightly forward of the tragus) is pointed from the top of the skin by the pointer 70, and each of the points inward is stored inward, for example, 20 [ mm] By calculating the moved point with the personal computer 26, it is possible to register the point (corresponding to the left and right condylar points).

  When the registration processing of the relative position of the mandibular shape feature point (position based on the position of the magnetic generator 15b) in step S5b is completed, the pointer 70 is returned to the pointer holder 74 in step S5c.

  Next, in step S5d, the magnetic generator 15a is attached to the upper jaw 22 side with an adhesive as shown in FIGS.

  For example, the magnetic generator 15a is attached on the center line of the face and on the horizontal line of the forehead 32 so as to be surrounded by the magnetic field sensor array 18a as shown in FIG. As will be described later, the reason for attaching the magnetic generator 15a to the upper jaw 22 side is that even when the upper jaw 22 moves during the measurement, the movement of the upper jaw 22 is subtracted from the movement of the lower jaw 24. This is because it is possible to detect and measure pure movement of only the lower jaw 24.

  In this way, the magnetic field sensor array 18a is disposed opposite to the front of the magnetic generator 15a on the forehead 32 side, and the magnetic field sensor array 18b is disposed opposite to the front of the magnetic generator 15b on the lower jaw 24 side.

  The forehead 32 was selected as the attachment location of the magnetic generator 15a without selecting the maxillary teeth or the like, which is a hard tissue, because the forehead 32 was formed integrally with the upper jaw. Although it is an upper soft tissue (skin tissue) and not strictly a rigid body, it is compared with a case where the distance from the magnetic generator 15b attached to the lower jaw dentition is, for example, attached to the upper teeth constituting the upper jaw 22. This is because the distance between the magnetic markers 16a to 16d is reduced and the magnetic field of the magnetic markers 16a to 18d can be detected more accurately by the magnetic field sensor arrays 18a and 18b. In addition, although the magnetization direction (magnetization direction J) of the magnetic markers 16a to 16d faces the front of the person to be measured 14 as shown in FIG. 3 and FIG. You don't have to go. Further, the magnetization directions J of the magnetic markers 16a to 16d may be in different directions. Here, the rectangle surrounding the arrow J indicating the magnetization direction J and the magnetic field direction J in FIG. 6 is a schematic one and does not actually exist.

  Next, in step S <b> 5 e, in order to set an arbitrary point (desired point, feature point, or representative point) of the upper jaw 22, the measurer or the like again removes the pointer 70 from the pointer holder 74 of the rack 46. The tip 76 is brought into contact with a predetermined position in the maxillary dentition, for example, the first molar mesial buccal cusp, and the three-dimensional coordinate position based on the position of the attached magnetic generator 15a is used as a magnetic field sensor array. The maximum likelihood method, which will be described later, is obtained from the output of the magnetic field sensor 20i.

  Here, when the distal end portion 76 of the pointer 70 is in contact with an arbitrary position of the upper jaw 22 of the person 14 to be measured, the mouse 56 as an input device follows a display on the monitor display 52 according to the display on the monitor display 52, for example, By clicking on the screen where “the pointer with the magnetic marker is being touched” is displayed, the position of the magnetic marker 72 inside the pointer is obtained from the magnetic field of the magnetic field sensor 20 i at that time, and the tip 76 of the pointer 70 is obtained. Find the position of.

  In this way, the relative position of the maxillary left and right first molar mesial buccal cusps with respect to the magnetic generator 15a attached to the forehead 32 is obtained, stored in the hard disk in the main body 50 of the personal computer 26, and registered. Keep it. In the same procedure, other characteristic points of the upper jaw 22, for example, several points such as the maxillary left and right canine cusps and the midpoint of the maxillary left and right central incisors are marked, and the relative position with respect to the position of the magnetic generator 15a is stored and registered By doing so, it is possible to measure the movements of the marked points simultaneously with the movement of the magnetic generator 15a.

  If the measurement subject 14 does not move the head during marking of an arbitrary point on the upper jaw 22 (feature point, for example, the midpoint of the maxillary left / right canine cusp or maxillary left / right central incisor), the magnetic markers 16a, 16b However, when the magnetic generator 15a is attached, the distal end portion 76 of the pointer 70 is brought into contact with the person 14 to be measured. Even when the head is moved when it is moved, it can be stored as a relative position of the attached magnetic generator 15a with respect to the magnetic markers 16a and 16b. Is possible.

  Next, when the registration processing of the relative position of the upper jaw-shaped feature point (position with respect to the position of the magnetic generator 15a) in step S5e is completed, the pointer 70 is returned to the pointer holder 74 again in step S5f. .

  Next, in step S6, the output of the magnetic field sensor 20i in the magnetic field sensor array 18a causes the magnetic markers 16a and 16b attached to the upper jaw from the distribution of two dipole magnetic fields (dipole magnetic fields by the magnetic markers 16a and 16b). In addition to determining the position and direction, the output of the magnetic field sensor 20i in the magnetic field sensor array 18b allows the magnetic markers 16c and 16d attached to the upper jaw from the distribution of the two dipole magnetic fields (dipole magnetic fields by the magnetic markers 16c and 16d). Find the position and direction. Here, a method for obtaining the positions and directions of the magnetic markers 16c and 16d will be described. However, the positions and directions of the magnetic markers 16a and 16b can be obtained only by changing the subscripts of symbols described below.

  First, as shown in FIG. 9, the position vector p1 from the origin position of the absolute coordinate system X0Y0Z0, which is a fixed point, to the origin position of the lower jaw coordinate system XbYbZb indicating the position of the magnetic marker 16c and the position vector p2 of the magnetic marker 16d are obtained. Ask.

In this case, the origin of the lower jaw coordinate system XbYbZb may be any position in the upper jaw 22 or the lower jaw 24, but here it is assumed to coincide with the center position of the magnetic marker 16c for simplicity. Further, the origin position of the absolute coordinate system X0Y0Z0, for example, and connecting it midpoints of the left and right of the magnetic field sensor 20 ₂₁ and 20 ₂₇ for constituting a magnetic field sensor array 18b.

  Under this assumption, the origin coordinates of the magnetic marker 16a, in other words, the origin coordinates of the lower jaw coordinate system XbYbZb are expressed by parameters (6 degree-of-freedom information) of position and direction angle (posture angle, rotation angle), and P (X, y, z, θ, φ, Ψ).

In this case, the measurement magnetic field Bmi detected by each magnetic field sensor 20i of the magnetic field sensor array 18b and the position of each magnetic field sensor 20i of each dipole magnetic field (dipole field) of each magnetic marker 16c, 16d whose magnetic moment is known. Where Bci is a calculated magnetic field, which is a calculated value in the above, the vector P (x, y, z, θ,...) From the measured magnetic field Bmi and the calculated magnetic field Bci by the maximum likelihood method or the like by the following equation (3). (φ, Ψ) parameters are obtained. In the case of the arrangement example of the magnetic field sensor 20 i in FIG. 2, the range of Σ in the formula (3) is i = 21 to 62.
Σ (Bmi−Bci) ² = 0 or local minimum value (3)

  In this case, since the number of markers and the magnetic moment are known, the parameters of the maximum likelihood method can be reduced, and the convergence and accuracy can be improved.

  The calculation for obtaining the positions and directions of a plurality of dipoles by the maximum likelihood method based on the least square method of equation (3) will be described in detail.

First, the above equation (3) is set as the evaluation function S (p) of the following equation (3-1).
S (p) = S (p1, p2) = Σ (Bmi−Bci) ² = 0
Or the minimum value (3-1)

However, in the equation (3-1), each value is as follows.
Bci = (1 / 4πμ) ×
[{(−M ₁ / p ₁ ³ ) + (3 (M ₁ · p ₁ ) p ₁ / p ₁ ⁵ )}
+ {(− M ₂ / p ₂ ³ ) + (3 (M ₂ · p ₂ ) p ₂ / p ₂ ⁵ )}] (3-2)
“·” In (M ₁ · r ₁ ) and (M ₂ · r ₂ ) is an inner product of vectors vector p ₁ = (xi−x, yi−y, zi−z)
Vector p ₂ = (xi−x, yi−y, zi−z) −d (−sin θ cos Ψ, cos φ cos θ cos Ψ−sin φ sin Ψ, sin φ cos θ cos Ψ + cos φ sin Ψ)
Vector p ₁ : Position vector of magnetic marker 16c, direction Vector p ₂ : Position vector of magnetic marker 16d, direction (xi, yi, zi): Position vector of i-th magnetic field sensor 20i n: Number of components of magnetic field sensor 20i M ₁ and M ₂ : Magnetic moments of magnetic markers 16c and 16d (known), respectively

  In the equation (3) defined above, if the evaluation function S (p) takes a minimum value in the vector p = q, the following equation (3-3) is established with m as the number of parameters to be described later. .

(∂S (p) / ∂p _j ) | _{p = q} = 0 (j = 1, 2... M) (3-3)
Substituting the above equation (3-1) into this equation (3-3) and expanding it, the following equation (3-4) is obtained with the range of Σ set to k = 1 to m.

Σ (∂ ² S / ∂p _j ∂p _k ) Δp _k = − (∂ ² S / ∂p _j ), (j = 1, 2,... M) (3-4)
The (3-4) equation is a simultaneous equation given by a matrix equation of m rows and m columns, which determine the vector Delta] p _k by solving the optimal solution from the vector p ^{(i + 1)} = vector p ⁱ + vector Delta] p _k A vector q can be obtained.

  It is to be noted that the magnetic field is proportional to the cube of the distance by obtaining the first differential value according to the distance between the magnetic fields Bmi and Bci and applying the maximum likelihood method only to the first differential value and the measured magnetic field Bmi. Considering it, the accuracy can be improved.

  The accuracy can be improved by using the measurement magnetic field Bmi of all the magnetic field sensors 20i. In addition, by using the measurement magnetic field Bmi of the magnetic field sensor 20i that can obtain a magnetic field strength equal to or higher than a predetermined value, it is possible to significantly reduce the measurement time while keeping the accuracy deterioration small.

  As in the above equation (3), when the calculation is performed using the magnetic moment, if the interaction between the magnetic markers 16c and 16d is small, it can be used as it is. However, if the interaction cannot be ignored, it is effective. It is necessary to calculate the effective magnetic moment.

  Furthermore, by setting the sampling interval for detecting the magnetic field to a time during which the movement of the jaw is within 10 to 20 [mm], the convergence is improved and the movement of the jaw can be tracked smoothly.

  Even in this case, when the calculation of the expression (3) does not converge or even when it converges, if the parameter solution is unnatural from the preceding and following trajectories, the solution at that point is excluded, The calculation may be repeated with the solution at the previous time as the initial value.

  In step S6 described above, the magnetization direction J of the magnetic markers 16c and 16d is different from the magnetization direction Jc (magnetization direction of the magnetic marker 16c) and Jd (magnetization direction of the magnetic marker 16d) as shown in FIG. The convergence calculation in the case of In this case, the magnetization direction Jd is inclined by an angle φd and an angle θd with respect to the magnetization direction Jc. That is, the relative magnetic field generation direction of the magnetization direction Jd with respect to the magnetization direction Jc is a direction indicated by an angle φd and an angle θd.

  When such a relative magnetic field generation direction exists, θ is replaced with (θ + θd) and (φ + φd) is replaced with φ shown in Equation (3-2), and then convergence calculation is performed. Thereby, even if the magnetization directions Jc and Jd of the magnetic markers 16c and 16d do not face the front of the person to be measured 14, the positions and directions of the magnetic markers 16c and 16d can be obtained.

  In addition, the description of step S6 described above is a method for obtaining the positions and directions of the magnetic markers 16c and 16d. However, when obtaining the positions and directions of the magnetic markers 16a and 16b, the coordinate system XbYbZb is shown in FIG. The position and direction of the magnetic markers 16a and 16b can be obtained by replacing with the upper jaw coordinate system XuYuZu and further setting i of the magnetic field sensor 20i (see FIG. 2, FIG. 3, etc.) to i = 1-20. .

  This calculation is explained by jaw movement through the temporomandibular joint. However, the present invention is not limited to jaw movement, and as a moving object to which the magnetic markers 16a to 16d are attached, each joint such as a human body, fingers, upper limbs, lower limbs, etc. The present invention can be similarly applied to an object that moves through the.

  Next, in step S7, parameters of the objects of the upper jaw 22 and the lower jaw 24 (6-degree-of-freedom information composed of 6 positions and relative directions) are obtained from the positions and directions of the magnetic markers 16a to 16d. Specifically, the relative positional relationship between the feature points of the upper jaw 22 and the lower jaw 24 stored in the personal computer by the marking process of step S5 and the positions and directions of the magnetic markers 16a to 16d obtained from step S6 are shown. Used to calculate the relative movement of the upper jaw 22 and lower jaw 24.

  In step S8, the relative movement can be converted into an image on the monitor display 52 and displayed as the movement of the lower jaw 24. That is, even if the magnetic generator 15a and the magnetic markers 16a and 16b of the forehead 32 are moved, they are processed so that they become fixed points on the screen, and the positions of the magnetic markers 16c and 16d accompanying the jaw movement With the movement, the positions of the plurality of feature points registered in step S5b can be read and simultaneously moved and displayed.

  Since the movement of the lower jaw 24 can be recorded on a hard disk or a digital video disk, it can be reproduced any number of times, and since slow reproduction, still reproduction, and high-speed reproduction are possible, It is possible to diagnose jaw movement from various viewpoints.

  In addition to the above-described measurement of the relative movement of the lower jaw 24 with respect to the upper jaw 22, the three-dimensional jaw movement measurement system 10 according to the present embodiment moves the upper jaw 22 with respect to the absolute coordinate system X0Y0Z0 (see FIG. 9) and the lower jaw. It is also possible to calculate 24 movements, convert these movements into images on the monitor display 52, and display them together.

  In this case, instead of steps S7 and S8, in step 9 after step S6, the parameters (6 degree of freedom information) of the object of the upper jaw 22 are obtained from the positions and directions of the magnetic markers 16a and 16b, and the magnetic marker 16c is obtained. , The parameter of the object of the lower jaw 24 is obtained from the position / direction of 16d.

  Specifically, the relative positional relationship between the feature points of the upper jaw 22 and the lower jaw 24 stored in the personal computer by the marking process in step S5, and the positions and directions of the magnetic markers 16a to 16d obtained from step S6. Are used to determine the position coordinates of the characteristic points (representative points) of the upper jaw 22 and the lower jaw 24, respectively. In this case, in step S5, the arrangement of the magnetic generators 15a and 15b and the feature points of the upper and lower jaws are each subjected to marking processing, so that the position coordinates of the representative points can be easily obtained. Thereby, the movement of the upper jaw 22 and the movement of the lower jaw 24 can be calculated respectively.

  Next, in step S10, the calculated movements of the upper jaw 22 and the lower jaw 24 are converted into images on the monitor display 52 as movements of the upper jaw 22 and the lower jaw 24 with respect to the origin O of the absolute coordinate system X0Y0Z0 and collectively. To display. Also in this case, along with the movement of the magnetic markers 16a to 16d accompanying the movement of the upper jaw 22 and the movement of the lower jaw 24, the positions of a plurality of feature points registered in step S5 can be read out and simultaneously moved and displayed. it can.

The origin position of the absolute coordinate system X0Y0Z0 described above may be, for example, a midpoint connecting the left and right magnetic field sensors 20 ₂₁ and 20 ₂₇ constituting the magnetic field sensor array 18b, as shown in FIG. It is good also as the midpoint which connected the upper and lower magnetic field sensors 20 ₁ and 20 ₅ which comprise the magnetic field sensor array 18a. In the three-dimensional jaw movement measurement system 10 according to the present embodiment, even if any midpoint is selected and the movements of the upper jaw 22 and the lower jaw 24 are measured, the movement of the upper jaw 22 relative to the absolute coordinate system X0Y0Z0 and the lower jaw The 24 exercises can be collectively displayed on the monitor display 52.

  Since each movement of the upper jaw 22 and the lower jaw 24 can be recorded on a hard disk or a digital video disk, it can be reproduced any number of times, and can also be played back slowly, still, and at high speed. Therefore, it becomes possible to diagnose jaw movement from various viewpoints.

  Here, one experimental result is shown in FIG. This experimental result is a result of measuring the relative movement of the lower jaw 24 with respect to the upper jaw 22 using the three-dimensional jaw movement measuring system 10. In FIG. 12, the origin O of the absolute coordinate xyz is set to a point (slightly forward of the tragus) as shown in FIG. 13, but the origin O of the absolute coordinate xyz is It is not limited to a point in the vicinity of the right mandibular head, and can be set on a hard tissue such as the left and right central incisors of the lower jaw 24 (applying position of the magnetic generator 15b).

  In this case, z = −2 [mm] at y = 0 [mm], z decreases as y increases, and at y = 55 [mm] (the central portion in front of the person 14 to be measured). z = −40 [mm]. That is, the change of the coordinate z in FIG. 12 indicates that the oral cavity (see FIG. 13) of the person to be measured 14 is open.

  As shown in FIG. 12, the coordinate x changes in the range of x = 10-15 [mm] with respect to the change of y = 0-55 [mm].

  On the other hand, when changing in the range of y = 0 to 55 [mm], the angle θ changes about 5 °, the angle φ changes about 40 °, and the angle ψ changes about 5 °. From these results, if the three-dimensional jaw movement measuring system 10 is used, it can be easily understood that the lower jaw 24 is moving relative to the upper jaw 22 with 6 degrees of freedom. Note that the change in the angle Ψ is caused by the movement of the lower jaw 24 at the temporomandibular joint.

  As described above, according to the above-described embodiment, the magnetic generators 15a and 15b having at least two magnetic markers 16a to 16d are attached to the upper jaw 22 and the lower jaw 24, which are two moving objects, respectively. Magnetic fields generated from the magnetic markers 16a to 16d are detected in a non-contact manner by the magnetic field sensors 20i constituting the magnetic field sensor arrays 18a and 18b arranged to face them.

  And the position and direction of each magnetic marker 16a-16d are calculated | required from the magnetic field detected by the magnetic field sensor 20i, Based on the obtained position and direction of each magnetic marker 16a-16d, and the positional information on the upper jaw 22 and the lower jaw 24, When the relative movement of the lower jaw 24 with respect to the upper jaw 22 is performed, information on six degrees of freedom of arbitrary positions and directions of the upper jaw 22 and the lower jaw 24 is calculated.

  In this case, the magnetic generators 15a and 15b are configured by fixing the two magnetic markers 16a to 16d to the upper surface of the fixing member 13 made of a nonmagnetic material with an adhesive or the like. The side surfaces of the magnetic generators 15a and 15b are attached to the upper jaw 22 and the lower jaw 24 with an adhesive or the like. As a result, the distance d, which is the relative distance between the two magnetic markers 16 a and 16 b and between the two magnetic markers 16 c and 16 d, is fixed by the fixing member 13.

  When the lower jaw 24 moves relative to the upper jaw 22, the magnetic field generated by the magnetic markers 16a to 16d includes a component of an angle Ψ with the magnetization direction J of the magnetic markers 16a to 16d as an axis. Come. Therefore, when the magnetic field sensor 20i detects the magnetic field and obtains the positions and directions of the magnetic markers 16a to 16d from the detection results of the magnetic field, the position and direction include the angle Ψ. That is, the positions and directions of the magnetic markers 16a to 16d are described by six positions and directions (6 degree-of-freedom information) including the angle Ψ (x, y, z, θ, φ, Ψ). Therefore, it is possible to easily measure the relative movement (6-degree-of-freedom movement) of the lower jaw 24 with respect to the upper jaw 22.

  If the magnetic field directions of the magnetic markers 16a to 16d are known in advance, the magnetic generator 16a is configured by fixing the two magnetic markers 16a and 16b with the fixing member 13, and the two magnetic markers 16c and 16d are separated. The magnetic generator 15b is configured by being fixed by the fixing member 13 of the other, whereby the direction of the magnetic field of the other magnetic marker 16b, 16d with respect to the direction of the magnetic field of the one magnetic marker 16a, 16c (relative magnetic field generation direction). Is also known. Thereby, for example, even when the magnetic markers 16c and 16d have different magnetization directions Jc and Jd, and there is a relative magnetic field generation direction between the magnetic markers 16c and 16d, the angle φd and the angle θd are set. By taking into consideration, it is possible to easily measure the 6-degree-of-freedom motion related to the upper jaw 22 and the lower jaw 24 of the measurement subject 14.

  Further, the magnetic field generated by the magnetic markers 16a and 16b of the magnetic generator 15a attached to the upper jaw 22 is detected by the magnetic field sensor 20i of the magnetic field sensor array 18a, and the magnetic marker 16c of the magnetic generator 15b attached to the lower jaw 24. , 16d is detected by the magnetic field sensor 20i of the magnetic field sensor array 18b. That is, the magnetic fields of the magnetic markers 16a and 16b and the magnetic fields of the magnetic markers 16c and 16d can be detected independently by different magnetic field sensors 20i.

  Therefore, the problem that the generated magnetic field interferes and the measurement accuracy of the magnetic field sensor 20i decreases as in the conventional three-dimensional motion measurement apparatus 100 can be avoided. Thereby, the measurement accuracy of the magnetic field sensor 20i is improved, and small magnetic markers 16a to 16d that can generate only a small magnetic field can be used for the magnetic generators 15a and 15b. Therefore, the magnetic generators 15a and 15b and the three-dimensional jaw movement measuring system 10 can be downsized.

  Moreover, since the magnetic field of the magnetic markers 16a and 16b and the magnetic field of the magnetic markers 16c and 16d are detected independently by different magnetic field sensors 20i, the movement of the upper jaw 22 and the movement of the lower jaw 24 are separately examined. Is also possible. Thus, the three-dimensional jaw movement measurement system 10 is not limited to the measurement of the relative movement of the upper jaw 22 and the lower jaw 24, and can also measure the movement of each object.

  Further, if the magnetic generators 15a and 15b are attached to the measurement subject 14 after the fixing member 13 is formed in a shape along the upper jaw 22 and the lower jaw 24, the detection accuracy of the magnetic field detected by the magnetic field sensor 20i is increased. The measurement accuracy of the three-dimensional jaw movement measurement system 10 can be further improved. It is also possible to reduce the burden on the person being measured 14.

  In addition, the magnetic generators 15a and 15b, particularly the magnetic markers 16a to 16d, are relatively small and light, do not require wiring, and can be used in a shielded space such as the oral cavity. Especially for children and the elderly, it is possible to measure exercise in a more natural state with little inconvenience.

  Further, since the magnetic field sensor 20i is less expensive than a CCD camera, it is possible to provide a significantly less expensive three-dimensional motion measurement device. Further, as shown in FIG. 2, the measurement is designed so as not to obstruct the field of view of the measured person 14 as much as possible. It can be said that it is a device.

  Further, according to the above-described embodiment, the number of magnetic markers 16 in the measurement region (magnetic field detection region) by the magnetic field sensor 20i is two during measurement of jaw movement. In general, since the position detection accuracy increases as the number of magnetic fields in the magnetic field detection region decreases, according to the above-described embodiment in which only two magnetic markers 16a and 16b (16c and 16d) are measured, The positions of the magnetic markers 16a and 16b (16c and 16d) can be detected with high accuracy. The magnetic markers 16a and 16b of the magnetic generator 15a attached to the forehead 32 are used for measuring the relative movement of the lower jaw 24 (magnetic markers 16c and 16d) with respect to the upper jaw 22 (pure movement of the lower jaw 24). Used to extract). Therefore, even if the upper jaw 22 moves a little during jaw movement, the movement can be removed.

Incidentally, 3-dimensional movement measuring apparatus and method Ru engaged to the present invention is not limited to the above embodiments without departing from the gist of the present invention, it is should be understood that various configurations.

1 is a schematic configuration diagram of a three-dimensional motion measurement system to which an embodiment of the present invention is applied. It is a perspective explanatory drawing of the positional relationship of the magnetic marker and magnetic field sensor which were distribute | arranged to the forehead and the mandibular central incisor. It is an electric circuit block diagram of the three-dimensional motion measurement system of FIG. 4A and 4B are perspective views of a magnetic generator in the three-dimensional motion measurement system of FIG. It is a flowchart with which it uses for operation | movement description of the three-dimensional motion measurement system of the example of FIG. It is side view explanatory drawing of the positional relationship of the magnetic marker and magnetic field sensor which were distribute | arranged to the forehead and the mandibular central incisor. It is perspective explanatory drawing which shows the state which has arrange | positioned the measurement stand with respect to a to-be-measured person. It is explanatory drawing of the relationship between the position of a magnetic marker, and a direction angle. It is explanatory drawing of the relationship between the position of a magnetic generator, and a direction angle. It is a relationship explanatory drawing which shows the magnetization direction of each magnetic marker of a magnetic generator. It is an explanatory view of the relationship between absolute coordinates and upper and lower jaw coordinates. It is a figure which shows the measurement result of 6 degree-of-freedom movement. It is explanatory drawing of the absolute coordinate of FIG. It is a typical block diagram of the conventional three-dimensional motion measurement system. FIG. 15 is a diagram illustrating the relationship between absolute coordinates and upper and lower jaw coordinates in the three-dimensional motion measurement system of FIG. 14.

Explanation of symbols

10 ... three-dimensional jaw movement measuring system 13 ... fixing member 14 ... the measurement subject 15, 15a, 15b ... magnetic generators 16,16A～16d ... magnetic marker 18, 18a, 18b ... magnetic sensor array 20, 20 20 ₁ to 20 ₆₂ 20i ... Magnetic field sensor 22 ... Upper jaw 24 ... Lower jaw 26 ... Personal computer

Claims (3)

In order to measure the relative motion of the first and second objects, the relative magnetic field generation direction of each magnetic marker as a magnetic field generation source is known at a position where the two magnetic markers are separated by a predetermined distance. First and second magnetic generators, each of which includes a fixing member that fixes the first and second objects, and is attached to the first and second objects.
At least six first magnetic field sensors for detecting a magnetic field generated from the magnetic marker of the first magnetic generator in a non-contact manner for measuring a six-degree-of-freedom motion of the first object;
At least six second magnetic field sensors for detecting a magnetic field generated from the magnetic marker of the second magnetic generator in a non-contact manner for measuring a six-degree-of-freedom motion of the second object;
First 6-degree-of-freedom information relating to the position and direction of the magnetic marker is obtained from the magnetic field detected by the first magnetic field sensor, and the position and direction of the magnetic marker are determined from the magnetic field detected by the second magnetic field sensor. Second 6-degree-of-freedom information relating to the first and second 6-degree-of-freedom information and the shapes of the first and second objects based on the obtained first and second 6-degree-of-freedom information. Signal processing means for calculating a dynamic movement;
With
The first object to which the first magnetic generator is attached is a part of the skull of the measurement subject that moves integrally with the upper jaw,
The three-dimensional motion measuring apparatus, wherein the second object to which the second magnetic generator is attached is a portion of the cranium that moves integrally with the lower jaw. The three-dimensional motion measuring apparatus according to claim 1 ,
Of the portion that moves integrally with the upper jaw, the first magnetic generator is attached to the forehead,
Of the portion that moves integrally with the lower jaw, the second magnetic generator is attached to the lower jaw teeth. First and second magnetic generators having a fixing member that fixes two magnetic markers at a predetermined distance so that the relative magnetic field generation direction of each magnetic marker that is a magnetic field generation source is known. Attaching to the relatively moving first and second objects, respectively,
A magnetic field generated from the magnetic marker of the first magnetic generator is detected in a non-contact manner by at least six first magnetic field sensors for measuring a six-degree-of-freedom motion of the first object, and the first A detection process in which a magnetic field generated from the magnetic marker of the second magnetic generator is detected in a non-contact manner by at least six second magnetic field sensors for measuring a six-degree-of-freedom motion of the second object;
First 6-degree-of-freedom information relating to the position and direction of the magnetic marker is obtained from the magnetic field detected by the first magnetic field sensor, and the position and direction of the magnetic marker are determined from the magnetic field detected by the second magnetic field sensor. Second 6-degree-of-freedom information relating to the first and second 6-degree-of-freedom information and the shapes of the first and second objects based on the obtained first and second 6-degree-of-freedom information. Signal processing process to calculate dynamic movement,
Have
The first and second objects that move relative to each other are a portion that moves integrally with the upper jaw and a portion that moves integrally with the lower jaw of the skull of the measurement subject 3 Dimensional motion measurement method.

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