JP2002355264A - Unit and method to measure three-dimensional motion and three-dimensional position detecting unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a subject friendly and low cost unit to measure motion of a jaw. SOLUTION: A magnetic marker 16a is mounted on the forehead 32 considered integral with the upper jaw 22 and another magnetic marker 16b on the cutting teeth in the lower jaw dentition as the typical point of the lower jaw 24. The magnetic markers 16a, 15b are arranged so that the magnetic directions are respectively arranged to face the right front of the face. A plurality of magnetic field sensors 20i (more than the number of magnetic markers × 5) to detect magnetic fields of the magnetic markers 16a, 16b are respectively placed facing the magnetic markers 16a, 16b. Changes of magnetic fields of the magnetic markers 16a, 16b are detected by the magnetic field sensors 20i, positions of the magnetic markers 16a, 16b are detected, and motion of the jaw is displayed on a display 52 based on the jaw shape. In that case, no inconvenience is given to the subject 14 because no wiring is required for the magnetic markers 16a, 16b. The viual field of the subject 14 is good.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative three-dimensional movement (for example, jaw movement,
3 to measure finger movement, upper limb movement, lower limb movement, etc.)
The present invention relates to a dimensional motion measuring device and a method thereof.

[0002] The present invention also relates to a three-dimensional position detecting device for easily detecting a desired position in an object.

[0003]

2. Description of the Related Art Conventionally, devices for measuring three-dimensional movement of an object have been provided on the market. For example, a magnetic jaw movement measuring device is used to measure the relative movement of the lower jaw with respect to the upper jaw, which is integrated with the head of the human body. In this magnetic jaw movement measuring device, a magnetic field sensor assembly is attached to the head of the subject by a belt or the like, and one magnet is attached to the lower incisor as a magnetic marker.

In this state, the displacement of one magnetic marker attached to the lower incisor due to the jaw movement of the subject is detected by a magnetic field sensor assembly mounted on the head, and the one magnetic marker is detected. Is displayed on a display device or the like, and this is identified as the movement of the lower jaw to measure the jaw movement.

However, in the magnetic jaw movement measuring apparatus according to the prior art, the shape of the magnetic field sensor assembly mounted on the head of the subject is relatively large, and the head of the subject is restrained. Therefore, there is a problem that the degree of inconvenience given to the subject in measuring the jaw movement is large.

Further, since it is difficult to securely fix the magnetic field sensor assembly mounted on the head of the person to be measured, there is a high possibility that the magnetic field sensor assembly will oscillate during the measurement of the jaw movement. In such a case, there is a problem that a measurement error of the jaw movement becomes large, and it becomes impossible to reproduce an accurate jaw movement.

Further, in this magnetic jaw movement measuring apparatus, only the movement of only one magnetic marker attached to the lower incisor is reproduced, and the jaw movement in a state where the lower jaw is recognized as a three-dimensional object is reproduced. There is also the problem that you cannot do that.

In order to solve these problems, an optical jaw movement measuring device has been provided. In this optical type jaw movement measuring device, in order to measure the movement of the upper jaw of the subject, one light source device is disposed with the head or the maxillary dentition of the subject as a fixed source, and the movement of the lower jaw is measured. Is measured, the other light source device is arranged with the lower dentition as a fixed source. The lower jaw is recognized as a three-dimensional object by photographing the change in position due to the jaw movement of these two light source devices with a CCD camera arranged and fixed around the jaw movement.
It is said that jaw movement can be measured (three-dimensional six degrees of freedom jaw movement measurement).

However, in the optical jaw movement measuring apparatus according to the prior art, when the light source device is arranged with the head of the subject as a fixed source, the light source device is relatively large, Since the head is constrained, the problem that the subject has a large degree of inconvenience in measuring the jaw movement has not been solved.

Further, since it is difficult to securely fix the light source device mounted on the head of the person to be measured, the light source device may swing during the measurement of the jaw movement, and the error in the measurement of the jaw movement may increase. The problem that it exists and cannot reproduce accurate jaw movement has not yet been solved.

In addition, since the light source device is photographed by a CCD camera, it must be exposed outside the oral cavity. When the upper dentition or the lower dentition is used as a fixed source, the inside and outside of the oral cavity are exposed. The need for a physical connector to connect makes it impossible to close the lips, and the relatively large and heavy light source device is attached to the lower jaw, so that chewing in a natural state without inconvenience In addition, there are problems such as inability to swallow and pronunciation, and as a result, it is not possible to measure the desired jaw movement.

Furthermore, since the CCD camera is relatively expensive, there is a problem that the jaw movement measuring device as a whole becomes expensive.

In order to measure the six-degree-of-freedom movement, it is essential to recognize the lower jaw as a three-dimensional object. Conventionally, however, an optical three-dimensional position detecting device using a CCD camera or an expensive radiograph There is also a problem that an apparatus or the like is used, and an apparatus that can easily and inexpensively measure the setting of an arbitrary point on the surface of an object is not provided.

As a useful conventional technique for detecting the position of a magnetic marker by a magnetic field sensor, there is a technique disclosed in Japanese Patent Application Laid-Open No. 2000-337811 by the present inventors.

However, this technique has the following problems.

First, this technique can determine the position and direction of a magnetic marker, but cannot measure the motion of an object such as a rigid body.

Second, the magnetic moment of the magnetic marker is
Since it is obtained as a variable, the number of variables increases, which is a factor that increases the error in the obtained position accuracy.

Third, it is assumed that simultaneous equations are solved by the Newton-Raphson method. However, when the number of magnetic field sensors is increased, it is difficult to obtain an optimum solution with high accuracy. I have.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described various problems, and improves inconvenience suffered by a subject and accurately reproduces a motion in a more natural state. Possible and at low cost with at least 2
It is an object of the present invention to provide a three-dimensional motion measuring device and a method thereof that can measure a relative three-dimensional motion between two objects.

Further, the present invention provides a method for detecting an arbitrary point on an object surface.
It is an object of the present invention to provide a three-dimensional position detecting device which can easily and at low cost detect a three-dimensional position with a simple configuration.

[0021]

SUMMARY OF THE INVENTION A three-dimensional motion measuring device according to the present invention comprises at least one magnetic marker disposed on at least two relatively moving objects, and at least one magnetic marker disposed on the object. A magnetic field sensor that detects the magnetic field of each magnetic marker in a non-contact manner for measuring 6 degrees of freedom motion, and a parameter of 6 degrees of freedom motion of each magnetic marker from the magnetic field detected by the magnetic field sensor; Signal processing means for calculating a relative motion of another object with reference to one object based on the shape of each object (the invention according to claim 1).

According to the present invention, at least one magnetic marker is disposed for at least two objects that move relatively, and the magnetic field of each magnetic marker is detected by a magnetic field sensor in a non-contact manner. The relative motion of another object with respect to one object is calculated by the signal processing means based on the shape of each object.

In this case, the magnetic marker can be made relatively small, light and thin, and wiring is not required. And three-dimensional motion can be measured.

Further, even if the magnetic marker is located in a physically shielded space, for example, in the mouth of the person to be measured, since the wiring and the like are unnecessary, the magnetic marker can be easily arranged. For example, mastication, swallowing, and sounding operations can be performed in a natural state with almost no difficulty.

Further, since the magnetic field sensor is inexpensive as compared with the CCD camera, the cost of the three-dimensional motion measuring device can be reduced.

For example, by arranging (attaching) one magnetic marker to each object that moves relatively, movement measurement with five degrees of freedom is possible.
When two magnetic markers are attached to the other object and two magnetic markers are attached to the other object, motion measurement with six degrees of freedom is possible.
Therefore, by attaching two or more magnetic markers to each object, it is possible to measure the motion of each object with six degrees of freedom. However, when the number of magnetic markers is increased, the calculation load on the signal processing device increases.

The number of components of the magnetic field sensor is at least five times the number of magnetic markers (the invention according to claim 2). For example, when the magnetic field sensor is a sensor that detects a component of one axis, at least five one-component magnetic field sensors (one-axis magnetic field sensors) are required for one magnetic marker, and the magnetic field sensor is a two-axis magnetic field sensor. In the case of a sensor that detects the detection component of (1), at least three two-component magnetic field sensors (two-axis magnetic field sensors) are required for one magnetic marker.
For one magnetic marker, two two-component magnetic field sensors (2
An axial magnetic field sensor) and one one-component magnetic field sensor (one-axis magnetic field sensor) may be used.

In this case, by using a magnetic field sensor array in which individual magnetic field sensors are integrated as the magnetic field sensor, handling such as installation and carrying is easy, and individual magnetic field sensors constituting the magnetic field sensor array are used. Since the relative position between them is known in advance, it is easy to calculate the parameters (the invention according to claim 3).

It is preferable that the magnetic field sensor is arranged so as to measure a magnetic field component in a magnetization direction of the magnetic marker. This is because the magnetic field input to the magnetic field sensor increases and the SN ratio improves. Conversely, SN
Since the ratio is improved, a magnetic marker having a small magnetizing force and a small volume can be used, and a magnetic marker having a smaller detection sensitivity can be used.

Further, by using an external magnetic field detection sensor for detecting an external magnetic field, an external unnecessary magnetic field such as terrestrial magnetism detected by the magnetic field sensor can be removed from the output of the magnetic field sensor. Only the magnetic field of the magnetic marker can be detected, and a more accurate three-dimensional movement can be obtained (the invention according to claim 5).

Further, based on the three-dimensional position calculated by the signal processing means, the 3
By providing the display means for displaying the three-dimensional movement, the measurer can visually recognize the three-dimensional movement (the invention according to claim 6). As the display means, for example, a CRT display or a liquid crystal display can be used.

In this case, the tip of the freely movable pointer is brought into contact with a desired part of the person to be measured to detect the position, whereby the position of the magnetic marker disposed on the object is determined as a reference. Then, the three-dimensional position of a desired part of the object can be calculated (the invention according to claim 7).

The above device selects at least two relatively moving objects on which the magnetic markers are located, respectively, a part of the skull that moves integrally with the upper jaw and a part that moves integrally with the lower jaw. Thus, the jaw movement can be accurately and easily measured (the invention according to claim 8).

In this case, by selecting the part that moves integrally with the lower jaw as the lower jaw teeth and arranging the magnetic marker, the teeth are considered to be a rigid body almost integral with the lower jaw unlike soft tissues such as the lower lip. Thus, the movement of the lower jaw can be measured more accurately (the invention according to claim 9).

It should be noted that a magnetic marker can be arranged on the upper teeth instead of the forehead (the invention according to claim 10). In this case, the distance between the magnetic markers becomes shorter, and the separation of the magnetic field becomes slightly difficult.However, as described above, the maxillary teeth are different from soft tissues such as the forehead, and are considered to be a rigid body that is almost integral with the maxilla. The jaw movement can be measured more accurately as compared with the arrangement of the jaw movement.

The magnetic field sensor is preferably arranged close to the periphery of the magnetic marker, and a one-axis, two-axis or three-axis sensor can be used (the invention according to claim 11).

The signal processing means can determine a parameter by the maximum likelihood method using the magnetic field around the magnetic marker detected by the magnetic field sensor as an ideal dipole magnetic field (the invention according to claim 12).

The magnetic field around the magnetic marker cannot be approximated to an ideal dipole magnetic field, and is a pseudo dipole magnetic field generated by a magnetic marker having a finite magnitude. The magnetic field sensor also has a finite magnitude. In this case, the correlation between the relative position and the magnetic field between the magnetic marker and each magnetic field sensor is determined in advance, and the parameter can be determined by the maximum likelihood method using the correlation.
3).

In this case, the theoretical value of the magnetic field at the position of the magnetic field sensor is obtained by a magnetic field analysis using a discretization method.
The parameter can also be obtained by the maximum likelihood method using this theoretical value (the invention according to claim 14).

The present invention is not limited to the jaw movement via the jaw joint, and includes at least two relatively movable objects on which magnetic markers are arranged, which are moved through each joint such as the human body, fingers, upper limbs, and lower limbs. The present invention can be similarly applied to an object to be changed.

According to the three-dimensional motion measuring method of the present invention, an arranging step of arranging at least one magnetic marker on at least two objects that move relatively, and a magnetic field of each magnetic marker arranged on the object A non-contact detection process using a magnetic field sensor for measuring 6 degrees of freedom motion, and obtaining a parameter of 6 degrees of freedom motion of each magnetic marker from the magnetic field detected by the magnetic field sensor. A signal processing step of calculating a relative motion of another object based on one object based on the shape of the object (the invention according to claim 16).

According to the present invention, the positions of the magnetic markers arranged with respect to at least two objects that move relatively are detected by the magnetic field sensor, and one object is identified based on the detection result and the shape of each object. The relative motion of another reference object is calculated. In this case, the magnetic marker is relatively small and light and does not require wiring, and can be used in a shielded space (part) such as the oral cavity. Absent. That is, it is possible to measure the movement of the subject in a more natural state. Further, since the magnetic field sensor is inexpensive as compared with the CCD camera, the cost of the three-dimensional exercise device can be reduced.

Also in this case, by using an external magnetic field detection sensor for detecting an external magnetic field, an external magnetic field such as geomagnetism can be removed from the output of the magnetic field sensor.
More accurate three-dimensional motion can be obtained.
Described invention).

Further, by providing a display step of displaying the three-dimensional movement of the at least two objects based on the calculated three-dimensional position, the measurer can visually recognize the three-dimensional movement (claim). Item 18)).

In addition, at least two relatively movable objects on which the magnetic markers are arranged are respectively selected as a part of the skull that moves integrally with the maxillary body and a part that moves integrally with the mandible. Thus, the jaw movement can be accurately and easily measured (the invention according to claim 19).

Still further, the three-dimensional position detecting device according to the present invention comprises a movable pointer having a magnetic marker, and a contact signal output for outputting a signal indicating the contact when the pointer contacts the surface of the object. Means, a magnetic field sensor for detecting the magnetic field of the magnetic marker constituting the pointer in a non-contact manner, and signal processing means for performing signal processing on the output of the magnetic field sensor, wherein the signal processing means The invention according to claim 20, wherein upon detecting a signal to be notified, a position of the magnetic marker is obtained from a magnetic field detected by the magnetic field sensor, thereby detecting a contact position of the pointer with the object. .

According to the present invention, it is possible to easily and inexpensively measure the shape of the surface of an object such as a jaw with a simple configuration. The contact signal output device can be configured separately from the pointer and operated manually.
Alternatively, it is also possible to automatically detect the contact by being integrated with the pointer and output it as a signal (wireless signal or wired signal).

This three-dimensional position detecting device can be used in the human body, jaw,
The present invention is useful when applied to a site that moves through a joint, such as a finger, an upper limb, or a lower limb (the invention according to claim 21).

Further, the three-dimensional motion measuring apparatus according to the present invention includes a fixed magnetic marker fixed to the surface of the object, and a magnetic marker capable of freely pointing at the surface of the object to detect the position of the surface of the object. A movable pointer having a marker, contact signal output means for outputting a signal indicating that the pointer has touched when the pointer touches the surface of an object, a magnetic field of the fixed magnetic marker and a magnetic marker constituting the pointer A magnetic field sensor that detects contactlessly,
Signal processing means for performing signal processing on the output of the magnetic field sensor, wherein the signal processing means detects the signal indicating that the magnetic field sensor has come into contact with the fixed magnetic marker from the magnetic field detected by the magnetic field sensor. The relative position of the object is obtained and registered in advance as a feature point of the object,
When the position of the fixed magnetic marker that moves according to the movement of the object is detected by the magnetic field sensor after the pointer is positioned outside the detection range of the magnetic field sensor, the detected position of the fixed magnetic marker is The feature point registered as a relative position from this position is read out, and the three-dimensional motion of the object as a solid is measured (the invention according to claim 22).

According to the present invention, one or more arbitrary points on the surface of the object represented by relative positions from the position of the fixed magnetic marker fixed on the surface of the object in advance are used. Is detected by a pointer and registered as a feature point. After the completion of the position detection registration by the pointer, when the movement of the position of the fixed magnetic marker associated with the movement of the object is detected, the characteristic point is read out, and the position of the fixed magnetic marker and the position of the characteristic point (the position of the fixed magnetic marker It is possible to simultaneously measure the three-dimensional motion of the registered position (not placed) three-dimensionally.

This three-dimensional motion measuring device is used for measuring the inside of the human body, the jaw,
It is useful when applied to a site that moves through joints such as fingers, upper limbs, and lower limbs (the invention according to claim 23).

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In addition,
In order to avoid complicating the drawing, the appearance, jaw shape, tooth shape, and the like of the subject 14 are deformed in the drawing.

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

FIG. 2 schematically shows an enlarged configuration in a state in which a part of the three-dimensional jaw movement measuring system 10 of FIG.

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

As shown in FIGS. 1 to 3, the three-dimensional jaw movement measuring system 10 basically includes a magnetic marker 16 such as a permanent magnet attached to a predetermined position of a subject 14 with an adhesive or the like. A magnetic field sensor array (also simply referred to as a magnetic field sensor) 18 (1) that is a magnetic field sensor that detects the magnetic field of each magnetic marker 16 in a non-contact manner for measuring the 6-DOF motion.
8a, and 18b), the magnetic field sensors 20i constituting the magnetic sensor array 18 (FIG. 2, as shown in FIG. 3, in this embodiment, the magnetic field sensor 20i (i = 1 to 14, the magnetic field sensor 20 ₁ to 20 up to ₇ and the magnetic field sensor 20 _{8-20 14,}
The position and direction of each magnetic marker 16 are determined from the magnetic field detected by the upper and lower seven magnetic field sensors (a total of 14 magnetic field sensors),
Based on the determined position and direction of each magnetic marker 16 and the shapes of the rigid upper jaw 22 and lower jaw (mandibular bone) 24,
It has a personal computer (PC) 26 as signal processing means for calculating the three-dimensional position of the upper and lower jaws 22, 24 in real time.

Since the magnetic field sensor array 18 is 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 set as a known position in the personal computer 26.
Can be stored.

As shown in FIGS. 1 and 3, the personal computer 26 includes a CPU, ROM,
A main unit 50 as a signal processing unit having a RAM, a hard disk, and the like; a monitor display 52 such as a CRT display connected to the main unit 50;
Keyboard 54 that functions as input means and the like connected to
And a mouse 56, and are housed on the upper shelf of a rack 46 that can be fixed and moved freely by the casters 45.

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

The rack 46 on which the personal computer 26 and the like are disposed is a measurement marker on which the magnetic marker 16 disposed on the subject 14 and the magnetic field sensor array 18 and an external magnetic field detection sensor 44 described later are disposed. It is arranged via the wiring 66 so as to be away from the stand 38 so as not to exert a magnetic interaction. As the wiring 66, a multi-core electric wire coated with an electromagnetic shield is used.

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

As shown in FIG. 1, a pointer holder 74 is fixed on the lower shelf plate of the rack 46, and a measurer (not shown) or the like can arbitrarily move the pointer holder 74 with his / her hand. A pointer 70 having a magnetic marker 72 therein, which is free to be inserted, is inserted in a freely removable state.

As shown in FIGS. 2 and 3, the pointer 70 is a pencil-like rod body having a built-in magnetic marker 72 as a magnet and having a substantially conical pointed tip 76. The material of the portion other than the magnetic marker 72 incorporated 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 center of) the magnetic marker 72 is known, and is stored and stored in the hard disk of the main body 50. The magnetic marker 72 is attached so that the magnetization direction of the magnetic marker 72 matches the axial direction of the pointer 70. In order to minimize measurement errors, it is preferable that the built-in magnetic marker 72 is arranged and fixed at a position as close as possible to the distal end portion 76. Of course, it can also be arranged at the tip 76.

In this embodiment, the magnetic marker 16
And the size of the magnetic marker 72 is 5 mm × 5 mm ×
A permanent magnet of a sintered magnet made of NdFeB (neodymium iron boron) having a large maximum energy product of about 2 mm (thickness) and a saturation magnetic flux density of about 1 [T (tesla)] is used. By using such magnetic markers 16 and 72,
In the magnetic field sensor 20i, 10 [mG (milligauss)] to
A magnetic field of about 100 [mG] can be detected. Further, in this embodiment, the magnetization direction (magnetization direction) J (see FIG. 3) of the magnetic marker 16 is directed outward from the subject 14 and the magnetic field detection direction of the magnetic field sensor 20i is It is set to match this magnetization direction J.

As the magnetic field sensor 20i and the external magnetic field detecting sensor 44, those using a Hall element, those using a magnetoresistive effect element, and high-frequency carrier type thin film magnetic field sensors (Magneto Impedance Sen)
sor) or a well-known sensor such as a flux gate sensor having a high-frequency excitation coil can be used. The three-axis fluxgate sensor is disclosed in detail, for example, in Japanese Patent Application Laid-Open No. 2000-337811.

In particular, when a high-frequency carrier type thin-film magnetic field sensor is used, the size of the head becomes 1 mm or less.
The detection sensitivity of the high-frequency carrier thin-film magnetic field sensor of 1 mm or less has a sensitivity substantially equal to or higher than that of a fluxgate sensor having a head size of about 10 mm.

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 flux gate sensor, the head size may be changed as necessary. Processing is performed assuming it is finite.

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

In the examples of FIGS. 1 to 3, the magnetic marker 1
6a and 16b indicate the subject 14 sitting on the chair 30.
In the forehead part 32 and the lower teeth (lower dentition) 34 of the lower incisor, they are respectively attached to the crown part of the lower incisor via an adhesive which can be easily removed.

As shown in FIG. 1, a headrest 29 for supporting the head of the subject 14 is attached to a backrest of a chair 30 on which the subject 14 sits. The headrest 29 is used to bring the position of the magnetic field sensor 20i as close as possible to the jaw 24 of each subject 14 and the subject 1
4 so that it can be moved up and down, left and right, and back and forth so as to correspond to the position of the head.

As shown in FIG. 2, at the time of measurement in which the magnetic field sensor 20i is placed close to the person 14 to be measured and opposed thereto, the magnetic field sensors 20i are respectively arranged so as to surround the magnetic markers 16a and 16b from the front of the face. The magnetic field sensor arrays 18a and 18b as a magnetic field sensor assembly including the magnetic field sensors 20i are mounted on a sensor holder 36.

As shown in FIG. 1, the sensor holder 36 to which the magnetic field sensor arrays 18a and 18b are attached
It is attached between the columns 40 of the measurement stand 38 which can be adjusted to a free position in the vertical direction (vertical direction) by a fixing screw 41. Each of the columns 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.
Is freely movable and fixed in the direction of the subject 14 by four casters 43 attached to the floor side of the base 42.

An external magnetic field detecting sensor 44, which is a three-dimensional magnetic field sensor for detecting an external magnetic field (external unnecessary magnetic field) such as terrestrial magnetism, is provided between the columns 40.
b, 39c, 39d) and a U-shaped frame 37. The external magnetic field detection sensor 44
5, it is possible to arrange and fix it at any position of the mounting portions 39a, 39b, 39c, 39d.

The optimal arrangement position of the external magnetic field detection sensor 44 is a position where the magnetic field acting on the magnetic marker 16 is so small that it can be ignored (basically, a position relatively far from the magnetic marker 16). And each magnetic field sensor 20
The position is such that a magnetic field equivalent to an external magnetic field including geomagnetism other than the magnetic marker 16 acting on i can be detected by three-axis components.

The external magnetic field detection sensor 44 is arranged to cancel the in-phase component of each magnetic field sensor 20i. The position where the magnetic field from the magnetic marker 16 becomes 0.1 [mG: milligauss] or less in order to also cancel the fluctuating (wobble) magnetic field component in the external magnetic field component (DC magnetic field component + fluctuating magnetic field component) including geomagnetism. preferable.

In this embodiment, as shown in FIG. 1, an external magnetic field detection sensor 44 is provided with a sensor holder integrally formed with a magnetic field sensor array 18 having a magnetic field sensor 20i via a frame 37. 36 and is integrally fixed to the pipe portion. Therefore, even if the column 40 is moved up and down so that the position of the magnetic field sensor array 18 corresponds to each individual person 14 and the sensor holder 36 is moved up and down, the spatial position of the magnetic field sensor 20i and the external magnetic field detection sensor 44 is maintained. Relationship does not change. Due to this configuration, each of the magnetic field sensors 20i is temporarily set in each of the mounting portions 39a to 39d.
If the offset relationship between the output of the external magnetic field sensor 44 and the output of the external magnetic field detection sensor 44 is adjusted and determined and stored in the hard disk or the like of the personal computer 26, there is an advantage that readjustment of the offset relationship becomes unnecessary. .

As a material of the entire measurement stand 38 shown in FIG. 1, it is preferable to use a non-magnetic material such as plastic resin, wood or stainless steel so as not to disturb the magnetic field from the magnetic marker 16 or an external magnetic field. Similarly, it is preferable to use a non-magnetic material for the material of the sensor holder 36, the frame 37, and the screw 35.

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

Main unit 50 of personal computer 26
Functions as a signal processing means as described above. This signal processing means uses an iterative calculation such as a maximum likelihood method based on an application program recorded in advance, as described later, and performs AD conversion. From the digital data of the magnetic field strength supplied via
6b is calculated in real time, the magnitude and direction of the external magnetic field are calculated based on the output of the external magnetic field detection sensor 44. When necessary, the position of the movable pointer 70 having the magnetic marker 72 inside is calculated. Calculate the position of the tip contact area. Further, 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 respect to the magnetic marker 16, and reads out the position when necessary.

Thus, the magnetic markers 16a, 16a
A three-dimensional position such as b is measured. The main body unit 50 stores the measured positions of the magnetic markers 16a, 16b and the like in the RAM and the hard disk and, based on these positions, displays a jaw movement image of the person corresponding to the subject 14 on the display 52 as a moving image. Display in real time.

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

First, in step S1, each magnetic field sensor 2
The output value of 0i is calibrated with the output value of the external magnetic field detection sensor 44, so-called calibration. This calibration is performed in a specific facility that is magnetically shielded in a factory of the manufacturer (manufacturer) of the jaw movement measuring system 10 or the like.

That is, an equal magnetic field (a magnetic field on the order of terrestrial magnetism)
To the external magnetic field detection sensor 44 and each magnetic field sensor 20i simultaneously, for example, sequentially in the order of three orthogonal axes, X axis, Y axis, and Z axis, and for each axis, the external magnetic field detection sensor 44 and each The relationship between the output value of the magnetic field sensor 20i (for example, the difference between the output of the external magnetic field detection sensor 44 and the output of each magnetic field sensor 20i) is set so that the output value of each magnetic field sensor 20i becomes a zero value or a negligibly small value. A correction coefficient is determined in advance, and a look-up table (referred to as a look-up table (table) for canceling (calibrating) external unnecessary magnetic field) is prepared. This look-up table is stored in a hard disk which is a storage medium in the main unit 50 of the personal computer 26. Instead of the lookup table, it may be stored as a calculation formula (calculation formula for canceling (calibrating) external unnecessary magnetic field).

That is, the look-up table (calibration table or calibration table) or the calculation formula (calculation formula for calibration) is the external magnetic field sensor 44 of each equal magnetic field.
When the detected magnetic field (vector) by the following equation (1) is Bre and the detected magnetic field (vector) by each magnetic field sensor 20i (i is the i-th meaning) of each equal magnetic field is Bmei, the value of the following equation (1) is 0 or The correction coefficient k that becomes the minimum value is determined as a function using the detected magnetic field Bre as a variable.

Bmei-kBre (1) After calibration by the manufacturer or the like, the jaw movement measuring system 10 is delivered to a measuring place such as a hospital, a clinic, or a health center.

Next, in step S2, when the power is turned on to the three-dimensional jaw movement measuring system 10 at the measuring place as shown in FIG. 1, the output of the magnetic field sensor 20 at the measuring place is changed to the external magnetic field detecting sensor. Calibrated automatically at the output of 44. That is, at the measurement location, the correction coefficient k, which is the subtraction ratio of the external magnetic field such as the terrestrial magnetism detected by the external magnetic field detection sensor 44, is calculated based on the external magnetic field (vector) Br at the measurement location. Alternatively, it is automatically calculated from the calibration formula.

The reason why the output of the magnetic field sensor 20 is corrected at the actual measurement location by the output of the external magnetic field detection sensor 44 is that the external magnetic field such as the terrestrial magnetism is not constant but varies with time or location. is there.

Therefore, according to the jaw movement measuring system 10 having the external magnetic field detecting sensor 44, even if an external magnetic field such as geomagnetism changes during measurement, such a noise component of variability is automatically generated. Removed.

When the power is turned on at the measurement location, the magnetic markers 16a and 16b
Not attached to 4. Also, the magnetic markers 16a,
16b is located at a sufficiently distant position 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 S3, the magnetic field sensor 20i is arranged by placing the measuring stand 38 facing the subject 14 sitting on the chair 30.

In this case, the measurement stand 38 is moved toward the subject 14 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 shown in FIG.
As shown in (1), the caster 43 of the measurement stand 38 is fixed such that the tip of the sensor holder 36 on the side of the subject 14 substantially coincides with the front surface of the face of the subject 14 when viewed from the side.

In this step S3, the magnetic field sensor array 18 is further adjusted at a predetermined height with respect to the person 14 to be measured. Specifically, for example, of the lower teeth in the lower jaw (mandibular bone) 24 of the subject 14, two middle incisors Ti
The holder 36 is moved up and down so that the position of the so-called front tooth (the position where the magnetic marker 16b is to be pasted) and the height of the lower magnetic field sensor array 18b coincide with each other. It is fixed to the support 40.

FIG. 6 shows a state in which the measuring stand 38, in other words, the magnetic field sensor 20i, is arranged on the person 14 to be measured. As shown in FIG.
8 has a magnetic field sensor 20i because the width L2 (see FIG. 1) is wider than the width L3 of the chair 30 which is set to be larger than the maximum width of the subject 14 between the upper arms. The sensor holder 36 can be arranged at a desired position with respect to the person 14 to be measured.

In this case, since the position of the external magnetic field detection sensor 44 in the height direction is set so as to be above the arm placed on the thigh of the person to be measured 14, the external magnetic field detection sensor 44 may come into contact with the person to be measured 14. Absent.

Further, since the headrest 29 is disposed on the back of the subject's 14 head, the subject 14 can support his / her own head naturally by the headrest 29 without any pressure. Can be moved up and down, left and right, and back and forth, so that the sticking position of the magnetic marker 16 can be as close to the magnetic field sensor array 18 as possible.

As described above, during the measurement, the subject 1
4 is a very small magnetic marker 16 as described later.
It is possible to take a jaw movement measurement or a medical examination in a state where only the body is attached, in other words, in a very free state without direct physical compression. As shown in FIGS. 5 and 6, during this measurement, the field of view of the subject 14 is hardly limited by the measuring device.

Therefore, by using the three-dimensional jaw movement measuring system 10 according to this embodiment, as described in the section of the prior art, the head of the subject is fixed by the belt-fixed magnetic field sensor assembly or the light source device. The inconvenience of fixing is eliminated. Therefore, the present invention can be applied to children and elderly people, which is difficult with the conventional device.

Next, in step S4, as shown in FIG. 6, the magnetic field sensor
By dismounting the screw 35 and moving up and down the frame 37 on which the external magnetic field detection sensor 44 is mounted in a state where the positions 8 are opposed to each other, the value of the above equation (1) becomes the minimum value at the measurement position. The optimum height of the external magnetic field detection sensor 44 is determined, and the frame 37, that is, the external magnetic field detection sensor 44 is mounted and fixed to the mounting hole 39 closest to the determined height position by the screw 35.

During the measurement by the three-dimensional jaw movement system 10, the calculation performed by the main body 50 of the personal computer 26 in relation to the external magnetic field detection sensor 44 is performed by calibrating each magnetic field sensor 20i (i is the i-th meaning). The previous output value (measured magnetic field: vector) is Bmi0, the detected magnetic field (vector) by the external magnetic field sensor 44 is Br, the constant based on the above correction table or correction formula is k, and the measured magnetic field of each corrected magnetic field sensor 20i is k. Is Bmi, the measured magnetic field (vector) Bmi can be expressed by the following equation (2).

Bmi = Bmi0−kBr (2) It can be seen from the equation (2) that noise with time variability of the external magnetic field can be eliminated.

During this measurement, the magnetic field sensor 20i having at least five components is arranged for one of the magnetic markers 16 attached to the subject 14. In this way, five degrees of freedom (x, y, z, θ,
φ) jaw movement can be observed.

However, as shown in FIG. 7, the angles φ and θ are the inclination (direction angle) φ of the vector P defined by the coordinates (x, y, z) from the origin O from the z-axis and the vector P. The inclination (direction angle) θ from the x-axis when projected onto the xy plane
Represents

Next, in step S5, the magnetic marker 16
And processing for marking the characteristic points of the upper and lower jaws. Note that, at the measurement locations shown in the example of FIG.
In the process of step 4, the magnetic marker 16 is not actually placed on the person 14 to be measured.

Here, the marking process of the characteristic points of the upper and lower jaw means an arbitrary point on the surface of the upper jaw 22 or the lower jaw 24, for example, in the case of the lower jaw 24, the point of the fossa of the lower right and left first molars and the vicinity of the left and right lower condyles. This is a process of setting feature points such as points as relative coordinates.

More specifically, the marking process of the characteristic points of the upper and lower jaws is performed with respect to the position of the magnetic marker 16 fixedly attached to the jaw of the subject 14 in the processing after step S6 described below. In this process, the relative positions (relative three-dimensional positions) of arbitrary points on the upper and lower jaws are recognized and registered (stored).

For this reason, first, in step S5a, one position in front of the lower jaw 24, in this case, as shown in FIG.
Of the lower teeth in the lower jaw (mandible) 24 of the subject 14,
A magnetic marker 16 taken out of the above-described magnetic shield box or the like is provided at the center of the crowns over two central incisors Ti.
b is attached. To be affixed to the teeth, the teeth are hard tissues,
Since it is considered to be almost integral with the mandible, by attaching it to the teeth, the lower jaw 24
This is because the movement of the person can be accurately 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 removes the pointer 70 from the pointer holder 74 of the rack 46, and Tip 76 of
At a predetermined position in the lower dentition, for example, both second molars Tm
(See FIG. 5). The three second molars Tm with respect to the position of the magnetic marker 16b which was brought into contact with the crown portion of FIG.
The dimensional coordinate position is obtained from the output of the magnetic field sensor 20i by the maximum likelihood method described later or the like.

In practice, when the distal end portion 76 of the pointer 70 is in contact with the second molar Tm of the subject 14, the mouse 56 as an input device is used to display a predetermined portion in accordance with the display on the display 52. For example, by clicking on a portion of the screen where "touching pointer with magnetic marker" is displayed, the position of magnetic marker 72 inside the pointer is obtained from the magnetic field of magnetic field sensor 20i at that time, The position of the part 76 is determined. The position of the distal end portion 76 is the position of the second molar Tm.

In this manner, the relative positions of the left and right second molars Tm in the mandibular dentition with respect to the magnetic marker 16b affixed over the central incisor Ti are obtained, and the relative positions in the main body 50 of the personal computer 26 are determined. Store and register on the hard disk. In a similar procedure, other characteristic points of the lower jaw 24 are marked, for example, several points such as a point of the lower right and left first molar fovea and a point near the right and left lower condyles, and the magnetic marker 16b is marked.
By storing and registering the relative position with respect to the position, the movement of several points marked at the same time as the movement of the magnetic marker 16b can be measured.

It is to be noted that, while the subject 14 is marking an arbitrary point of the lower jaw 24 (a characteristic point, for example, a point in the central fossa of the lower right and left first molars and a point in the vicinity of the lower right and left jaws), the head or jaw is moved. If it is not moved, the magnetic marker 16b is not required, and any point on the lower jaw 24 can be marked without using the pointer 70. However, when the magnetic marker 16b is attached, the tip 76 of the pointer 70 is Even when the head or the jaw moves when it is brought into contact with the person to be measured 14, the position can be stored as a relative position with respect to the magnetic marker 16 b attached to the lower jaw 24. Marking can be performed.

In the marking of an arbitrary point on the lower jaw by the pointer 70 (to grasp the relative position), the user touches the tip 76 of the pointer 70 with a desired point to store and register the coordinate position as the desired point. , Subject 1
The coordinate position can be registered only for the point on the surface of No. 4.

However, in practice, it is necessary to observe the movement of a point inside the person 14 to be measured. In such a case, the position can be calculated and registered by the personal computer 26. . For example, a point (slightly forward of the tragus) near the right and left condyles is pointed from the skin with a pointer 70.
To the inside of the straight line connecting the left and right points pointed and stored by the pointer 70, for example, 20 [m
m] By calculating the moved point by the personal computer 26, it is also possible to measure the movement of that point (corresponding to the left and right condylar points).

When the registration processing of the relative position of the characteristic point of the lower jaw shape (position based on the position of the magnetic marker 16b) in step S5b is completed, in step S5c,
The pointer 70 is returned to the pointer holder 74.

Next, in step S5d, as shown in FIGS. 2 and 5, the magnetic marker 16a is placed on the upper jaw 22 side.
Is attached with an adhesive.

The magnetic marker 16a is positioned on the center line of the face and, as shown in FIG.
Affix on a horizontal line at the same height as a. As described later, the reason why the magnetic marker 16a is attached to the upper jaw 22 is that even when the upper jaw 22 moves during the measurement, the motion of the upper jaw 22 is subtracted from the motion 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 marker 1 on the forehead 32 is
A magnetic field sensor array 18a is disposed in front of 6a,
The magnetic field sensor array 18b is opposed to the front of the magnetic marker 16b on the lower jaw 24 side.

Note that the forehead 32 was selected without selecting the hard tissue, such as the upper teeth, as the attachment location of the magnetic marker 16a, because the forehead 32 is a frontal scale of the frontal bone formed integrally with the upper jaw. Although it is the upper soft tissue (skin tissue) and cannot be said to be strictly rigid, the magnetic marker 1 attached to the lower dentition
The distance between the magnetic markers 16a and 16b is reduced by 5 times or more as compared with the case where the magnetic markers 16a and 16b are arranged on the upper teeth forming the upper jaw 22, for example. The magnetic marker 16 at 18b
This is because it is possible to more accurately detect the magnetic field of each of a and 16b. The direction of magnetization (magnetization direction J) of the magnetic markers 16a and 16b is, as shown in FIGS.
To face the front. Here, in FIG. 5, the rectangle surrounding the arrow indicating the direction J of the magnetization and the direction J of the magnetic field is a schematic one, and does not actually exist.

Next, in step S6, the output of the magnetic field sensor 20i in the magnetic field sensor arrays 18a and 18b is used.
The positions and directions of the magnetic markers 16a and 16b arranged on the upper and lower jaws are obtained from the combined distribution of the two dipole magnetic fields (dipole magnetic fields).

For this purpose, as shown in FIG. 8, first, from the origin position of the absolute coordinate system X0Y0Z0 which is a fixed point, the origin position of the upper jaw coordinate system XuYuZu indicating the position of the magnetic marker 16a and the position of the magnetic marker 16b are shown. The position / direction (vector) Pu0, Pb0 up to the origin position of the lower jaw coordinate system XbYbZb is obtained.

In this case, the origin of the upper jaw coordinate system XuYuZu and the lower jaw coordinate system XbYbZb is the upper jaw 22 or the lower jaw 2
4 may be any position, but here, for simplicity,
It is assumed that the magnetic markers 16a and 16b coincide with the respective center positions. Further, the origin position of the absolute coordinate system X0Y0Z0, for example, and connecting it midpoint vertically center of the magnetic field sensor 22 ₄ and 22 ₁₁ of the magnetic field sensor array 18.

Under this assumption, the two magnetic markers 16
a, the origin coordinates of 16b, in other words, the upper jaw coordinate system XuY
The coordinates of the origin of uZu and the lower jaw coordinate system XbYbZb are represented by parameters of a position and a direction angle (posture angle), respectively, and Pu0 (x1, y1, z1, θ1, φ1), Pb0
(X2, y2, z2, θ2, φ2).

In this case, the measured magnetic field Bmi detected by each magnetic field sensor 20i and the dipole magnetic field (dipole field) of each magnetic marker 16a, 16b whose magnetic moment is known at the position of each magnetic field sensor 20i. When the calculated magnetic field, which is a calculated value, is Bci, the measured magnetic field Bm
From the i and the calculated magnetic field Bci, the vector Pu0 (x1, y1, z1,
θ1, φ1), Pb0 (x2, y2, z2, θ2, φ
Find each parameter of 2). Magnetic field sensor 20 of FIG. 2 example
In the case of the arrangement example of i, in Expression (3), the range of Σ is i = 1 to 1.
n = 1 to 14.

Σ (Bmi−Bci) ² = 0 or minimum value (3) In this case, since the number of markers and the magnetic moment are known, the parameters of the maximum likelihood method are reduced, and the convergence and accuracy are improved. Can be done.

The calculation for finding the positions and directions of a plurality of dipoles by the maximum likelihood method using the least squares method of equation (3) will be described in detail.

[0124] To account for comprehensibility of by appearance of expression, placed where the vector PU0, Pb0 respectively simply a vector p _1, p _2. At this time, the above equation (3) is set as an evaluation function S (p) of the following equation (3-1).

S (p) = S (p ₁ , p ₂ ) = Σ (Bmi−Bci (p ₁ , p ₂ )) ² = 0 or maximum value (3-1) where expression (3-1) , Each value is as follows.

[0126] _{Bci (p 1, p 2)} = (1 / 4π) × [{(-M 1 / r 1 3) + (3 (M 1 · r 1) r 1 / r 1 5)} + {( -M in ^{_{2 / r 2 3) + (}} 3 (M 2 · r 2) r 2 / r 2 5)}] ... (3-2) (M 1 · r 1) and (M ₂ · r ₂₎ " - "inner product vector p ₁ = vector (x1, y1, z1, θ1 , φ1) vector _{p 2 = (x2, y2,} z2, θ2, φ2) vector p = (x1, y1, z1 , θ1, φ1, x2
y2, z2, θ2, φ2) Vector r ₁ = (x1, y1, z1) − (xi, yi,
zi) Vector r ₂ = (x2, y2, z2) − (xi, yi,
zi) Vector p ₁ : Position vector and direction of magnetic marker 16a Vector p ₂ : Position vector and direction of magnetic marker 16b (xi, yi, zi): Position vector of i-th magnetic field sensor 20i n: Component of magnetic field sensor 20i Number vectors M ₁ , M ₂ : magnetic markers 16a, 16b, respectively
Vector r ₁ : a position vector from the i-th magnetic field sensor 20i to the magnetic marker 16a vector r ₂ : a position vector from the i-th magnetic field sensor 20i to the magnetic marker 16b is defined as above ( In the expression 3), the evaluation function S
If (p) takes the minimum value in the vector p = q, m
The following equation (3-3) holds as the number of parameters described below.

(∂S (p) / ∂p _j ) | _{p = q} = 0, (j = 1, 2,..., M) (3-3) ), The range of Σ is set as k = 1 to m, and the following (3-4)
An expression is obtained.

Σ (∂ ² S / ∂p _j ∂p _k ) Δp _k = − (∂ ² S / ∂p _j ), (j = 1, 2,... M) (3-4) 4) expression, m-m is a simultaneous equation given by a matrix equation of the column, obtains a vector Delta] p _k by solving this vector p ^{(i + 1)} = vector p ⁱ + vector Delta] p _k optimal solution from which the vector q Can be requested.

Note that the first order differential value based on the distance between the magnetic fields Bmi and Bci is obtained, and the maximum likelihood method is applied only to the first order differential value and the measured magnetic field Bmi, so that the magnetic field is proportional to the cube of the distance. In consideration of this, accuracy can be improved.

The measured magnetic field Bmi of all magnetic field sensors 20i
The accuracy can be improved by using. 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 more than a predetermined value, the measurement time can be significantly reduced while deterioration in accuracy is kept small.

As shown in the above equation (3), when the calculation is performed using the magnetic moment, if the interaction between the magnetic markers 16a and 16b is small, it may be used as it is. Needs to calculate the effective magnetic moment.

Further, the magnetic marker 1 attached to the lower jaw 24
Assuming that the movement of 6b is within 70 (up and down) × 40 (left and right) × 30 (back and forth) mm ³ and that the movement of the magnetic marker 16a attached to the upper jaw 22 is within 30 × 30 × 30 mm ³ , By limiting the range of solutions using the maximum likelihood method,
It is possible to improve the convergence and shorten the calculation time.

Further, by setting the sampling interval for detecting the magnetic field to a time when 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.

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

This calculation has been described with reference to the jaw movement via the jaw joint, but is not limited to the jaw movement.
a, at least two relatively moving where the 16b is located
The present invention can be similarly applied to an object that moves through each joint, such as the human body, fingers, upper limbs, and lower limbs.

Next, the parameters of the objects of the upper jaw 22 and the lower jaw 24 are obtained from the position directions of the magnetic markers 16a and 16b.

In this case, in the upper jaw coordinate system XuYuZu
(X)_u, Y_u, Z _u) And the lower jaw coordinates
Let the coordinates of an arbitrary point in the system XbYbZb be (x_b, Y_b,
z_b).

[0138] Further, the above arbitrary point coordinates as seen from the absolute coordinate system X0Y0Z0 each _{(x u0, y u0, z} u0),
(X _b0 , y _b0 , z _b0 ).

At this time, jaw coordinates (x _u , _yu , z _u ),
_{(X b, y b, z} b) the absolute coordinates (x _u0, y _u0,
z _u0 ) and (x _b0 , y _b0 , z _b0 ) are converted into the following (4)
It is obtained by the equation and the equation (5). In Equations (4) and (5), the leftmost three-row, three-column matrix on the right side is called a transformation matrix, and each component (each parameter) is a direction of the maxillary coordinate system XuYuZu with respect to the absolute coordinate system X0Y0Z0. Cosine is the direction cosine of the lower jaw coordinate system XbYbZb with respect to the absolute coordinate system. Note that the vectors Pu0, Pb0
(See FIG. 8) are the coordinates P of the magnetic marker 16a of the upper jaw and the magnetic marker 16b of the lower jaw, which have already been obtained.
u0 (x1, y1, z1), Pb0 (x2, y2, z
2).

[0140]

(Equation 1)

[0141]

(Equation 2)

Hereinafter, the expression (5) mainly relating to the movement of the lower jaw will be described. Since the equation (4) is the same, a description thereof will be omitted except where necessary.

Since the transformation matrix in the equation (5) is the direction cosine, the following equations (6) to (11) hold.

L _1b ² + l _2b ² + l _3b ² = 1 ... (6) m _1b ² + m _2b ² + m _3b ² = 1 ... (7) n _1b ² + n _2b ² + n _3b ² = 1 ... (8) l _{2b l 3b + m 2b m 3b +} n 2b n 3b = 0 ... (9) l 3b l 1b + m 3b m 1b + n 3b n 1b = 0 ... (10) l 1b l 2b + m 1b m 2b + n 1b n 2b = 0 ... ( 11) In all six equations of equations (6) to (11), there are nine variables, so the degree of freedom is 3 (the number obtained by subtracting the number of equations from the variables).

Here, assuming that the magnetization directions J of the magnetic markers 16a and 16b are parallel and are respectively parallel to the Xu axis and the Xb axis (they are originally set to be parallel). Equations (12) to (14) hold.

L ₁ = cos θ sin φ (12) m ₁ = sin φ sin θ (13) n ₁ = cos φ (14) That is, the following equations (15) to (20) hold.

L1b = cosθu · sinφu (15) m1b = sinθu · cosφu (16) n1b = cosφu (17) 12b = cosθb · sinφb (18) m2b = sinθb · cosφb… (19) φ2 (20) By substituting the expressions (15) to (20) into the above expressions (4) and (5), the following expressions (21) and (22) are obtained.

[0148]

(Equation 3)

[0149]

(Equation 4)

Considering the transformation matrices of the equations (21) and (22), there are six equations and five equations (one equation has a relationship of right side = left side, so there are only five equations). , That is, the solution cannot be obtained.

Here, the absolute coordinate system X0Y0Z
0, upper jaw coordinate system XuYuZu, and lower jaw coordinate system XbY
In bZb, it is assumed that Yu // Yb // Y0 and the y coordinate are parallel to each other.

By this assumption, equation (4) and (21)
In the equation, yu0 // yu, m1u = m3u = 0, m2u =
1, θu = 0 °, and in Expressions (5) and (22),
yb0 // yb, m1b = m3b = 0, m2b = 1, θ
Since b = 0, Equations (21) and (22) become Equations (23) and (24) shown below, respectively.
The transformation matrices shown in the equations (6) to (11) have 5 variables, 5
It becomes an equation, and variables (φu, l2u, l3u, n2u, n3u) and (φb,
l2b, l3b, n2b, n3b) can all be obtained.

[0153]

(Equation 5)

[0154]

(Equation 6)

When the positions and directions of the magnetic markers 16a and 16b are obtained from the above-described equations (23) and (24), the coordinates of the arbitrary positions of the upper jaw 22 and the lower jaw 24 from the absolute coordinate system are obtained. Becomes possible.

Here, in step S7, the relative movement of the lower jaw 24 with respect to the upper jaw 22 is determined by the following equation (25).

[0157]

(Equation 7)

In step 10, the relative movement can be converted into an image on the display 52 and displayed as a movement of the jaw. That is, even if the magnetic marker 16a of the forehead 32 is moved, the magnetic marker 16a is processed so as to be a fixed point on the screen, and the magnetic marker 1a accompanying the jaw movement is moved.
Along with the movement of the position 6b, the positions of a plurality of feature points registered in step S5b can be read out, moved simultaneously, and displayed.

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

When the subject 14 performs a jaw movement with a complicated movement and Yu // Yb // Y0 cannot be assumed, as shown in FIG. 9, the magnetic marker 16b attached to the lower jaw teeth is used. With the magnetic marker 16b and the magnetic marker 16
c, the parameters of the jaw movement can be calculated with three-dimensional six degrees of freedom by respectively attaching them to the lower dentition, for example, near the crown of the left and right canines.

As described above, according to the above-described embodiment,
At least one magnetic marker 16a, 16b is disposed (mounted) on each of the upper jaw 22 and the lower jaw 24, which are examples of at least two objects that move relatively, and the magnetic field of each magnetic marker 16a, 16b is applied to them. Non-contact detection is performed by the magnetic field sensors 20i having the magnetic field sensor array 18 arranged to face each other. Next, the positions and directions of the magnetic markers 16a and 16b are determined from the magnetic field detected by the magnetic field sensor 20i, and based on the positions and directions of the determined magnetic markers 16a and 16b and the shapes of the upper jaw 22 and the lower jaw 24,
The three-dimensional positions of the upper jaw 22 and the lower jaw 24 are calculated. In this case, the magnetic markers 16a, 16b
Is relatively small and light, requires no wiring, and can be used in a shielded space such as the oral cavity. It is possible to measure movement.

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 measuring device. Further, as shown in FIG. 2, since the measurement is designed so as not to obstruct the field of view of the subject 14 as much as possible, the subject 14 does not feel a feeling of oppression, and in that respect, the measurement is gentle to the subject 14. It can be said that it is a device.

According to the above-described embodiment, the number of magnetic markers 16 in the measurement area (magnetic field detection area) by magnetic field sensor 20i during measurement of jaw movement is two. Generally, the smaller the number of magnetic fields in the magnetic field detection area, the higher the position detection accuracy.
According to the above-described embodiment in which a and 16b are measured, the positions of the magnetic markers 16a and 16b can be detected with extremely high accuracy. In addition, in the upper jaw 22, forehead 32
Are used to measure the movement of the lower jaw 24 (magnetic marker 16b) relative to the upper jaw 22 (to extract the pure movement of the lower jaw 24). Therefore, even if the upper jaw 22 slightly moves during the jaw movement, the movement can be eliminated.

Furthermore, according to the above-described embodiment, the pointer 70 with the magnetic marker 72 that the measurer or the person 14 can freely move while holding it is prepared, and the magnetic marker 72 in the pointer 70 is an object. When a user touches the second molar teeth Tm or the like on the surface of a certain subject 14 by clicking on the mouse 56 or the like functioning as a contact signal output means, a personal computer as a signal processing means outputs a signal indicating that the contact has been made. 26 to the main unit 50. At this time, the main body unit 50 can calculate the three-dimensional position of an arbitrary part of the object by obtaining the position of the magnetic marker 70 from the magnetic field detected by the magnetic field sensor 20i. That is, the movement of the lower jaw 22 can be recognized as a three-dimensional object. By registering the characteristic point of the jaw shape as a position relative to the fixed magnetic marker 16b in this way, when the movement of the magnetic marker 16b is detected, the characteristic point of the registered jaw shape is registered. Is read out and displayed three-dimensionally at the same time, whereby the jaw movement can be diagnosed accurately and easily.

As the contact signal output means, a switch (not shown) is provided for the pointer 70 instead of the mouse 56, and the switch is provided in accordance with the pressing force when the magnetic marker 70 is pressed against the surface of the object. Is turned on. In this on state, even if an infrared signal is sent to an infrared receiving device (not shown) attached to the main body 50 of the personal computer 26, the contact position of the magnetic marker 70 can be changed. Can be measured.

By using the pointer 70 having such a configuration, the magnetic field sensor 20i, and the personal computer 26 as signal processing means, a simple three-dimensional position detecting device for measuring the surface shape of an object such as a jaw shape can be obtained. The measurement can be easily performed at a low cost with the configuration.

In the following, various modifications of the present invention will be described.

The magnetic field sensor 20 may be a one-axis sensor, a two-axis sensor, or a sensor having three or more axes. However, the one-axis sensor measures only a large component of the magnetic field strength in the magnetization direction of the magnetic marker 16 in a concentrated manner. Has the advantage that

The two-axis sensor has the advantages that the volume and cost can be reduced as compared with the one-axis sensor, and that the accuracy can be improved by measuring the portion of the magnetic field that is strong in a plane.

Since the three-axis sensor can measure three or more components with a single core, the number of sensors can be reduced, and even if a rigid body such as a jaw moves complicatedly, it can be measured with three-axis components. Accuracy can be improved because one of the components increases.

As in the arrangement shown in FIG. 2, as shown in FIG. 10, the magnetic markers 16a and 16b arranged on the lower jaw 34 and the forehead 32 of the lower jaw 24, respectively, have the same height as the magnetic markers 16a and 16b. Magnetization direction) on extension of J and magnetic field sensor 20i
Are arranged so that the measurement directions (magnetic field detection directions) coincide with each other.
Since the magnetic field strength is closest to the dipole magnetic field on the extension of the magnetization direction, the SN ratio increases, and the measurement accuracy improves.

The magnetic field sensors 20i may be arranged on a straight line. However, as shown in FIG. 10 (similarly in FIG. 2), the magnetic field sensors 20i are arranged so as to be shifted along a curved surface close to the shape of the face, so that the magnetic field sensor 20i is displaced. Since the interaction between the sensors 20i can be suppressed, and the magnetic field sensor 20i can be brought closer to the magnetic marker 16, the accuracy is improved. In addition, although the magnetic field sensors 20i are arranged in one row each in the upper and lower rows, the accuracy of the maximum likelihood method is further improved by providing two or more rows. It should be noted that the fact that two or more rows may be applied is also applicable to the following description with reference to FIG.

The magnetic marker 16b can be attached (adhered) to the back side (lingual side) of the tooth. In some cases, the magnetic marker 16 cannot be adhered to the front side (labial side) of the lower incisor due to over-occlusion or the like. The ability to perform jaw movements is a huge advantage.

As shown in FIG. 11, the magnetic field sensors 20i can be arranged vertically with respect to the magnetic markers 16b arranged on the lower teeth 34. In this way, even if the magnetic marker 16b moves up and down, the magnetic field sensor 20i in which the magnetic field of the magnetization direction J component of the magnetic marker 16b is arranged vertically.
Thereby, it is possible to measure as a large magnetic field strength, and the measurement accuracy is improved.

In this case, as shown in FIG. 12, a magnetic field sensor 20i is applied to the magnetic marker 16b so as to measure the magnetic field of the front and rear components in front of the face, and a two-dimensional magnetic field in the lateral direction is applied to the side of the face. Two rows of magnetic field sensors 20i to be measured
May be arranged.

Further, as shown in FIG.
By arranging the three-axis magnetic field sensors 20i along the face vertically and horizontally with respect to the lower jaw 24 (the magnetic marker 16)
Even if the movement in b) is complicated, any of the components can be detected as a strong magnetic field, so that the measurement accuracy is improved.

Further, as shown in FIG. 14, the magnetization directions J of the magnetic markers 16a and 16b are arranged in the left and right direction of the face,
Correspondingly, by arranging the magnetic field sensor 20i having the magnetic field detection direction in the left and right direction on the left and right sides (left and right sides of the face) of the magnetic markers 16a and 16b, the front of the face becomes empty. The movement of the fourteen jaws can be more easily observed. Further, since the magnetic field sensor 20i can detect the magnetic field in the magnetization direction J, the measurement accuracy is improved.

Further, as shown in FIG. 15, when the magnetization directions J of the magnetic markers 16a and 16b are set in the vertical direction, a magnetic field sensor 20i whose magnetic field detection direction is aligned with the magnetic marker 16a is located above the magnetic marker 16a. By arranging the magnetic field sensor 20i arranged along the shape of the lower jaw 24 with the magnetic field detection direction aligned with the magnetic marker 16b along the shape of the lower jaw 24, the magnetic field in the magnetization direction J is detected, and the measurement accuracy is improved. Since the front and side surfaces are empty, the measurer can more easily observe the movement of the face of the subject 14.

Since the magnetic marker 16 does not rotate with the magnetization direction J as the rotation axis, in other words, since the rotation direction of the magnetization direction J and the rotation direction of the jaw motion do not match, the measurement with substantially six degrees of freedom is required. Become.

As shown in FIG. 16, the arrangement combination of the magnetic markers 16 is not limited to the combination of only the magnetic field sensors 16a and 16b (represented by symbols (16a, 16b)) in the example of FIG. And magnetic field sensor 16g
Combination of only (the last molar on the left side in the upper jaw) (meaning that the magnetic field sensor 16a is removed)
6b, 16g). In this combination (16b, 16g) (the same is true for the combination of only 16b and 16h), the magnetic marker 16b can be fixed to the hard tissue of the upper and lower jaws, and the lower jaw fixes the magnetic marker 16b at the position with the largest amount of momentum. Jaw movement measurement accuracy is improved.

The magnetic markers 16d and 16d
In the case of fixing to the last molars on the opposite sides of the upper jaw 22 and the lower jaw 24 as in the combination of only h (16d, 16h), the position becomes maximum apart in the dentition which is a hard tissue, so that the measurement accuracy is low. improves.

When both are hard tissues and it is desired to increase the displacement and improve the accuracy, a combination of only the magnetic marker 16f and the magnetic marker 16b (16f, 16b)
As shown in FIG. In this case, the magnetization directions J are, for example, perpendicular to each other (the magnetization directions J of one magnetic marker 16f) so that the magnetic field interaction between the magnetic markers 16f and 16b is reduced.
Is the vertical direction, the magnetization direction b of the other magnetic marker 16b is oriented in the horizontal direction. In addition,
In practice, it is often desirable that the magnetization direction J of the magnetic marker 16b disposed on the lower jaw 24 does not go up and down. When the rotational motion and the magnetization direction J are the same,
This is because the detection accuracy of the rotation angle decreases.

The three-dimensional jaw movement measuring system 10 according to this embodiment is a system for measuring the movement of the upper jaw 22 and the lower jaw 24 which are rigid bodies relatively moving via the jaw joint, so-called jaw movement. The invention is generally applicable to at least two objects that move relatively.

For example, the present invention can be applied to the relative motion of the lower jaw relative to the upper jaw via the temporomandibular joint, the relative motion of the lower arm relative to the upper arm of the forearm via the elbow joint, and the relative motion of the lower leg relative to the thigh via the knee joint. It is.

In this case, as shown in FIG. 17 to FIG. 19, when there are two objects 111 and 112 which move within the angle α with respect to the fulcrum 110, the magnetization directions j are substantially parallel to each other. (FIG. 17: Magnetic marker 16j and magnetic marker 16k) or by being arranged so as to be substantially perpendicular to each other (FIG. 18: Magnetic marker 16j and magnetic marker 16l), the interaction of the magnetic field of each magnetic marker 16 is reduced. The measurement accuracy with a magnetic field sensor not shown is improved. As shown in the magnetization direction J of the magnetic marker 16m and the magnetic marker 16n in FIG. 19, it is not preferable that the magnetization direction J is aligned.

That is, it is preferable to arrange the plurality of magnetic markers 16 in parallel, perpendicular, or twisted positions (positions that are not on the same plane), because it is possible to reduce the interaction of magnetic fields.

The arrangement of the magnetic field sensor 20i is shown in FIG.
The arrangement described with reference to FIGS.
7 and FIG. 18 can be applied in the same manner, and the description is omitted.

Further, the relative movement with respect to three or more objects can be measured. The relative movement of the upper arm and the forearm via the shoulder joint and the elbow joint with respect to the chest where the magnetic markers are arranged, and the hip joint and the knee joint with respect to the abdomen. It can be applied to the relative movement of the thigh and the lower leg via the.

As shown in FIG. 20, in the above-described embodiment, when the parameters are obtained by using the maximum likelihood method, the magnetic marker 16 and the magnetic field sensor 20i are each set to the ideal (infinitely small) dipole. Assume a magnetic field and a magnetic field sensor. That is, it is preferable to use as small as possible the magnetic marker 16 and the magnetic field sensor 20i.

In this case, the magnetic moment of the magnetic field sensor 16 for generating the magnetic flux line 120 is represented by the vector M and the magnetic field sensor 2
The calculated magnetic field at 0i (measurement point) is represented by vector B. At this time, as described in the above equation (3-2), the calculated magnetic field B
Assuming that a vector between the magnetic marker 16 indicated by a point and the magnetic field sensor 20i in FIG. 20 is r, the following equation (26) holds.

B = (１ ／ π) ｛− (M / r ³ ) +3 (M · r) r / r ⁵ ｝ (26) where “r ³ ” and “r ⁵ ” are scalar amount,"·"
Represents the inner product of the vectors.

However, even in the case where the magnetic marker 16 and the magnetic field sensor 20i have a finite size in relation to the object or the like to be measured, the first or second
According to the method described above, parameters can be calculated using the maximum likelihood method.

First Method (Method Using Actual Measurement Value Table) As shown in FIG. 21, a magnetic marker 16x having a finite pseudo dipole magnetic field, generating a magnetic flux line 121, and a finite magnetic field sensor 20x are used. In some cases, as shown in an actually measured calibration table 122 (see FIG. 23), a known coordinate position (vector r ^(x) , declination θ
^(x), the magnetic field sensor 20x in deflection angle ^{φ (x)) (x =} 1,
At each position of 2... I), a magnetic field Bm ^{(x) as} shown in FIG.
Is measured in advance.

In this manner, the coordinates (r ^(x) , which are the relative positions between the magnetic marker 16x and each magnetic field sensor 20x,
θ ^(x) , φ ^(x) ) is obtained and registered (stored) in a calibration table 122 shown in FIG. 22, which is a correlation between the measured magnetic field B (x) measured by each magnetic field sensor 20x. When calculating the parameters of the maximum likelihood method, the parameters of the plurality of magnetic markers 16x can be obtained with high accuracy by referring to the calibration table 122 which is a lookup table. If the data of the measurement magnetic field Bm measured during the measurement of the three-dimensional motion is data that does not exist in the calibration table 122, the data is interpolated by a plurality of measurement magnetic fields in the calibration table 122 that are close to the value of the measurement magnetic field Bm. , Coordinates can be obtained.

[0195] The second method (method using a discretization technique) In this case, in FIG. 21, the magnetic field sensor 20x having a volume V, given the calculated magnetic field Bc ^(i), the theory of this calculation field Bc ⁽ⁱ⁾ The value is obtained by the following equation (27).

Bc ⁽ⁱ⁾ = (∫ _s B (i) dv) / V (27) Here, “∫ _s ” means integral with respect to the volume V.

By solving this equation (27) by a discrete method such as the finite element method using the Maxwell equation, the coordinates (r ^(x) , θ ^(x) , φ ^(x) ) and the calculation magnetic field Bc ⁽ⁱ⁾ can be calculated. The magnetic field theoretical value table 12 shown in FIG.
4 is obtained. If this magnetic field theoretical value table 124 is used as a lookup table in the calculation of the maximum likelihood method, the parameters of the plurality of magnetic markers 16x can be obtained with high accuracy. Also in this case, interpolation processing can be used.

It is to be noted that the present invention is not limited to the above-described embodiment, but can adopt various configurations without departing from the gist of the present invention.

[0199]

As described above, according to the present invention, a magnetic marker is arranged on at least two objects that move relative to each other, and a change in the magnetic field of the magnetic marker accompanying the movement of the object is measured by a non-contact magnetic field sensor. By doing so, the effect of being able to measure the motion of the object in a more natural state with a small burden on the person to be measured or the object to be measured is achieved.

According to the present invention, unlike the prior art, there is no need to use a CCD camera, so that the cost of the apparatus itself can be reduced.

Further, according to the present invention, it is sufficient that a minute magnetic marker can be attached to the subject, so that the burden on the subject at the time of measurement is small. Therefore, the present invention is suitably applied to, for example, measurement of jaw movement, and is useful for diagnosis and treatment of temporomandibular disorders, jaw deformities, malocclusions, and the like. In the maxillofacial region, by arranging a plurality of magnetic markers on the tongue, it is also possible to measure tongue movement three-dimensionally, and it is also applicable to diagnosis and treatment of swallowing disorders and pronunciation disorders.

Furthermore, not limited to the maxillofacial area,
It is possible to measure a subject in a natural state even in a part where a plurality of objects constituting an upper limb, a lower limb, etc. make a complex movement through a plurality of joints. Is also applicable.

Further, according to the present invention, a three-dimensional position of an object can be detected with a simple configuration including a freely movable pointer with a magnetic marker, a magnetic field sensor, and signal processing means.

Further, according to the present invention, the position of the fixed magnetic marker fixed to the surface of the object is set as a reference, and one of the arbitrary points on the object surface expressed by the relative position from the reference position is set to 1 The above plurality of points are detected by a pointer and registered as feature points. After the position detection by the pointer is completed, when the movement of the position of the fixed magnetic marker accompanying the movement of the object is detected, the feature points are read out, so that the three-dimensional movement of the position of the fixed magnetic marker and the position of the feature point is obtained. It can be measured three-dimensionally at the same time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a three-dimensional motion measurement system to which an embodiment of the present invention is applied.

FIG. 2 is an explanatory perspective view of a positional relationship between a magnetic marker disposed on a forehead and a lower central incisor and a magnetic field sensor;

FIG. 3 is an electric circuit block diagram of the three-dimensional motion measurement system of FIG. 1;

FIG. 4 is a flowchart provided for describing the operation of the three-dimensional motion measurement system of the example of FIG. 1;

FIG. 5 is a side view illustrating a positional relationship between a magnetic marker disposed on a forehead and a lower central incisor and a magnetic field sensor.

FIG. 6 is an explanatory perspective view showing a state in which a measurement stand is arranged with respect to a subject;

FIG. 7 is an explanatory diagram of a relationship between a position of a magnetic marker and a direction angle.

FIG. 8 is a diagram illustrating the relationship between absolute coordinates and upper and lower jaw coordinates.

FIG. 9 is an explanatory diagram of an arrangement of three magnetic markers for obtaining six degrees of freedom.

FIG. 10 is an explanatory diagram of an example of arrangement of a magnetic marker and a magnetic field sensor.

FIG. 11 is an explanatory diagram of another arrangement example of a magnetic marker and a magnetic field sensor.

FIG. 12 is an explanatory diagram of yet another arrangement example of a magnetic marker and a magnetic field sensor.

FIG. 13 is an explanatory diagram of still another arrangement example of a magnetic marker and a magnetic field sensor.

FIG. 14 is an explanatory diagram of still another arrangement example of a magnetic marker and a magnetic field sensor.

FIG. 15 is an explanatory diagram of still another arrangement example of a magnetic marker and a magnetic field sensor.

FIG. 16 is an explanatory diagram of various arrangement examples of a magnetic marker.

FIG. 17 is an explanatory diagram of an example of arrangement (parallel) of a magnetic marker on two objects that move relatively to a fulcrum.

FIG. 18 is an explanatory diagram of another arrangement example (perpendicular to each other) of a magnetic marker on two objects that move relative to a fulcrum.

FIG. 19 is an explanatory diagram of an example of an undesirable arrangement of magnetic markers in which magnetic fields interfere with each other.

FIG. 20 is an explanatory diagram when it is assumed that a magnetic marker and a magnetic field sensor are ideal.

FIG. 21 is an explanatory diagram in the case where each of a magnetic marker and a magnetic field sensor is assumed to be finite.

FIG. 22 is an explanatory diagram for creating a calibration table on the assumption that the calibration table is finite.

FIG. 23 is an explanatory diagram of a calibration table.

FIG. 24 is an explanatory diagram of a magnetic field theoretical value table when it is assumed to be finite.

[Explanation of symbols]

Reference Signs List 10 3D jaw movement measuring system 16, 16a, 16b, 72 Magnetic marker 18 Magnetic field sensor array 20 Magnetic field sensor 22 Upper jaw 24 Lower jaw 26 Personal computer 36 Sensor holder 38 Measurement stand 40 Column 42 ... Base 44 ... External magnetic field detection sensor 46 ... Rack 50 ... Main body 52 ... Display 53 ... Jaw movement image 54 ... Keyboard 56 ... Mouse 60 ... Printer 62 ... A
D converter 64 Power supply unit 66 Wiring 70 Pointer 72 Magnetic marker Tm Second molar Teeth Central incisor XuYuZu Upper jaw coordinate system XbYb
Zb: Lower jaw coordinate system X0Y0Z0: Absolute coordinate system

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Yabugami Aoba, Aoba-ku, Aoba-ku, Sendai-shi, Miyagi Prefecture Kameoka Residence (2) 14-21 (72) Inventor Hideo Mitani 1-3-3 Kadogoro, Aoba-ku, Sendai-shi, Miyagi -5 (72) Inventor Hiroyasu Kintaka 1-39-14 Kunimigaoka, Aoba-ku, Sendai, Miyagi Prefecture F-term (reference) 2F063 AA04 BA29 BB08 BD15 DA01 DB06 DC08 GA01 KA01 LA19 2G017 AA03 AA09 BA15 BA18 2G053 AB01 CA05 CA06 CC01 DB04 DB14 4C052 AA20 NN01 NN16

Claims (23)

[Claims] 1. At least two magnetic markers disposed on at least two objects that move relatively to each other, and the magnetic field of each magnetic marker disposed on the object is set to 6
A magnetic field sensor for non-contact detection for measuring the degree of freedom motion, and a parameter of 6 degrees of freedom motion of each magnetic marker from the magnetic field detected by the magnetic field sensor, based on the obtained parameters and the shape of each object, A signal processing means for calculating a relative motion of another object with respect to one object as a reference. 2. The three-dimensional motion measuring apparatus according to claim 1, wherein the number of components of the magnetic field sensor is at least five times the number of magnetic markers. . 3. The three-dimensional motion measuring apparatus according to claim 1, wherein the magnetic field sensor is configured as a magnetic field sensor array in which individual magnetic field sensors are integrated. . 4. The three-dimensional motion measuring device according to claim 1, wherein the magnetic field sensor is arranged to measure a magnetic field component in a magnetization direction of the magnetic marker. 5. The three-dimensional motion measuring device according to claim 1, further comprising: an external magnetic field detection sensor for detecting an external magnetic field other than the magnetic field of the magnetic marker; A three-dimensional motion measuring apparatus, which is used to cancel the external magnetic field detected by a magnetic field sensor that detects a magnetic field. 6. The three-dimensional motion measuring device according to claim 1, further comprising: display means for displaying a three-dimensional motion of the at least two objects based on the three-dimensional position calculated by the signal processing means. A three-dimensional motion measuring device, comprising: 7. The three-dimensional motion measuring device according to claim 1, further comprising a magnetic marker arbitrarily movable, wherein the signal processing means is configured to move the magnetic marker to a desired portion of the object. Three-dimensional motion, wherein, when touched, a position of a desired part of the object is calculated based on a position of a magnetic marker disposed on the object by detecting the touched position. measuring device. 8. The three-dimensional motion measuring device according to claim 1, wherein the at least two relatively moving objects on which the magnetic markers are arranged are a part of the skull that moves integrally with the upper jaw, and a lower jaw. A three-dimensional motion measuring device, which is a part that moves integrally. 9. The three-dimensional movement measuring device according to claim 8, wherein the magnetic marker is arranged on a forehead and moves integrally with the lower jaw in a part moving integrally with the upper jaw. A three-dimensional motion measuring device, wherein the magnetic marker is arranged on lower jaw teeth. 10. The three-dimensional movement measuring apparatus according to claim 8, wherein the magnetic marker is arranged on an upper jaw and the part moves integrally with the lower jaw. A three-dimensional motion measuring device, wherein the magnetic marker is arranged on a lower jaw tooth. 11. The three-dimensional motion measuring device according to claim 1, wherein the magnetic field sensor is a one-axis, two-axis, or three-axis magnetic field sensor disposed close to a periphery of the disposed magnetic marker. A three-dimensional motion measuring device, characterized in that: 12. The three-dimensional motion measuring device according to claim 1, wherein the signal processing means sets a magnetic field around the magnetic marker detected by the magnetic field sensor as an ideal dipole magnetic field,
A three-dimensional motion measuring device, wherein the parameter is obtained by a maximum likelihood method. 13. The three-dimensional motion measuring device according to claim 1, wherein said signal processing means is such that a magnetic field around said magnetic marker detected by said magnetic field sensor is a pseudo dipole magnetic field and said magnetic field sensor has a finite dimension. In the case of, the correlation between the magnetic field actually measured by each magnetic field sensor with respect to the relative position between the magnetic marker and each magnetic field sensor is obtained in advance, and the maximum likelihood method is used using the correlation between the relative position and the measured magnetic field The three-dimensional motion measuring device, wherein the parameter is obtained by: 14. The three-dimensional motion measuring device according to claim 1, wherein said signal processing means is such that a magnetic field around said magnetic marker detected by said magnetic field sensor is a pseudo dipole magnetic field and said magnetic field sensor has a finite dimension. Wherein a theoretical value of the magnetic field at the position of the magnetic field sensor is determined by a magnetic field analysis by a discretization method, and the parameter is determined by a maximum likelihood method using the theoretical value. 15. The three-dimensional motion measuring apparatus according to claim 1, wherein the at least two relatively moving objects on which the magnetic markers are arranged are connected to each other through joints such as a human body, fingers, upper limbs, and lower limbs. A three-dimensional motion measuring device, characterized in that it is a moving part. 16. An arranging step of arranging at least one magnetic marker on at least two objects which move relatively, and changing a magnetic field of each magnetic marker arranged on the object by 6
A detection process for non-contact detection by a magnetic field sensor for measuring the degree of freedom motion; a parameter of 6 degrees of freedom motion of each magnetic marker from the magnetic field detected by the magnetic field sensor; a parameter obtained and a shape of each object; A signal processing step of calculating a relative movement of another object with respect to one object based on the method. 17. The three-dimensional motion measuring method according to claim 16, further comprising detecting an external magnetic field other than the magnetic field of the magnetic marker by an external magnetic field detection sensor, and detecting the magnetic field of each of the magnetic markers in a non-contact manner. A method for measuring three-dimensional motion, comprising a step of canceling the external magnetic field detected by a sensor. 18. The three-dimensional motion measuring method according to claim 16, further comprising the step of displaying the three-dimensional motion of the at least two objects based on the three-dimensional position calculated in the signal processing step. A three-dimensional motion measuring method, characterized in that: 19. The three-dimensional movement measuring method according to claim 16, wherein the at least two relatively moving objects are a part of the skull that moves integrally with the upper jaw and a part that moves integrally with the lower jaw. And a three-dimensional motion measurement method. 20. A freely movable pointer having a magnetic marker; contact signal output means for outputting a signal indicating that the pointer has touched when the pointer touches the surface of an object; and the magnetic marker constituting the pointer A magnetic field sensor that detects the magnetic field of the magnetic field in a non-contact manner; and a signal processing unit that performs signal processing on an output of the magnetic field sensor. The position of the pointer touching the object is detected by obtaining the position of the magnetic marker from the detected magnetic field.
Dimensional position detection device. 21. The three-dimensional position detecting device according to claim 20, wherein the object is a part that moves through each joint, such as a human body, jaw, finger, upper limb, and lower limb. Position detection device. 22. A fixed magnetic marker fixed to a surface of an object, a movable pointer having a magnetic marker capable of freely pointing at the surface of the object to detect a position of the surface of the object, When the pointer contacts the surface of the object, a contact signal output unit that outputs a signal indicating that the pointer has touched, a magnetic field sensor that detects the magnetic field of the fixed magnetic marker and the magnetic marker of the pointer in a non-contact manner, Signal processing means for performing signal processing on the output of the magnetic field sensor, the signal processing means, when detecting a signal indicating that the contact, the pointer to the fixed magnetic marker from the magnetic field detected by the magnetic field sensor The relative positions of the constituent magnetic markers are obtained and registered in advance as feature points of the object, and the pointer is detected by the magnetic field sensor. When the position of the fixed magnetic marker that moves according to the movement of the object is detected by the magnetic field sensor after being set to the outside position, the position of the detected fixed magnetic marker and the relative position from this position are determined. A three-dimensional motion of the object as a three-dimensional object by reading the registered feature points. 23. The three-dimensional motion measurement according to claim 22, wherein the object is a part that moves through each joint, such as a human body, jaw, finger, upper limb, and lower limb. measuring device.