JP2014039641A - Multi-axial force detection device and brain activity measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-axial force detection device capable of measuring a direction and a dimension of force generated by movement of a subject, the movement having multi-directional freedom degrees.SOLUTION: A force detection device 100 for detecting force from a subject for a movement issue during measurement of a cranium part of the subject by an MRI apparatus includes a load cell section 110 one end side of which is fixed to a stationary base 102 and that includes a holding part 104 at the other longitudinal end. The load cell section 110 includes a first parallel flat plate portion 121 that is formed of a side part of a first through-hole 120 opened penetrating through an elastic member 112; a second parallel flat plate portion 123 that is formed of a side part of a second through-hole 122 opened penetrating through the elastic member 112; and first and second gauges 130 and 132 that detects deformations of the first and second parallel flat plate portions.

Description

  The present invention relates to a multi-axis force detection device, and more particularly to a configuration of a multi-axis force detection device that can be used during measurement by a brain activity measurement device. The present invention also relates to a configuration of a brain activity measurement device using such a multi-axis direction force detection device.

  As a method of imaging the cross-section of the brain and whole body of a living body, a nuclear magnetic resonance imaging (MRI) method that uses the nuclear magnetic resonance phenomenon of atoms in the living body, particularly hydrogen nuclei, is a human clinical image. It is used for diagnosis.

  When applied to the human body, the nuclear magnetic resonance imaging method has the following features, for example, compared to “X-ray CT” which is a similar tomographic image of the human body.

  (1) An image having a density corresponding to the distribution of hydrogen atoms and the signal relaxation time (reflecting the strength of atomic bonding) can be obtained. For this reason, the lightness and darkness corresponding to the difference in tissue properties is exhibited, and the difference in tissue is easily observed.

  (2) The magnetic field is not absorbed by the bone. For this reason, it is easy to observe the part (intracranial, spinal cord, etc.) surrounded by bones.

  (3) Since it is not harmful to the human body like X-rays, it can be used in a wide range.

  Such nuclear magnetic resonance imaging uses the magnetic properties of hydrogen nuclei (protons) that are contained most in each cell of the human body and have the greatest magnetism. The movement in the magnetic field of the spin angular momentum responsible for the magnetism of the hydrogen nucleus is classically compared to the precession of the coma.

  In the following, for the purpose of explaining the background of the present invention, the principle of nuclear magnetic resonance is briefly summarized with this intuitive classic model.

  The direction of the spin angular momentum of the hydrogen nuclei (the direction of the rotation axis of the coma) as described above is directed in a random direction in an environment without a magnetic field, but is directed in the direction of the lines of magnetic force when a static magnetic field is applied.

  In this state, when the oscillating magnetic field is further superimposed, if the frequency of the oscillating magnetic field is a resonance frequency f0 = γB0 / 2π (γ: a coefficient specific to the substance) determined by the strength of the static magnetic field, the resonance causes The energy moves and the direction of the magnetization vector changes (precession increases). When the oscillating magnetic field is cut in this state, the precession returns to the direction in the static magnetic field while returning the tilt angle. By detecting this process from the outside with an antenna coil, an NMR signal can be obtained.

  Such a resonance frequency f0 is 42.6 × B0 (MHz) for hydrogen atoms when the strength of the static magnetic field is B0 (T).

  Furthermore, in the nuclear magnetic resonance imaging method, it is possible to visualize the active site of the brain with respect to an external stimulus or the like by using the change in the detected signal according to the change in the blood flow. Such a nuclear magnetic resonance imaging method is particularly called fMRI (functional MRI).

  In fMRI, an ordinary MRI apparatus equipped with hardware and software necessary for fMRI measurement is used.

  Here, the change in blood flow brings about a change in the NMR signal intensity utilizing the fact that oxygenated and deoxygenated hemoglobin in blood has different magnetic properties. Oxygenated hemoglobin has a diamagnetic property and does not affect the relaxation time of hydrogen atoms present in the surrounding area, whereas deoxygenated hemoglobin is a paramagnetic material and changes the surrounding magnetic field. Therefore, when the brain is stimulated, local blood flow increases, and oxygenated hemoglobin increases, the change can be detected as an MRI signal. For the stimulation to the subject, for example, visual stimulation, auditory stimulation, or execution of a predetermined task (task) is used (for example, Patent Document 1).

  Here, in brain function research, the increase of nuclear magnetic resonance signal (MRI signal) of hydrogen atoms corresponding to the phenomenon (BOLD effect) in which the concentration of deoxygenated hemoglobin in erythrocytes in microarrhythmias and capillaries decreases. The brain activity is measured by measuring.

  In particular, in research on human motor functions, brain activity is measured by the magnetic resonance imaging apparatus while causing a subject to perform some kind of exercise. As the operation performed by the subject, an object gripping motion or the like is conceivable. When the subject grips the detection unit of the gripping force detection device, the subject detects the force acting on the gripping force detection device, and the subject grips the gripping motion. Brain activity during exercise is measured by the magnetic resonance imaging apparatus.

  However, since such a gripping force detection device generally uses a magnetic metal material such as a strain gauge, there are problems that various adverse effects occur when it is brought into the magnetic resonance imaging device. is there. For this reason, the force detection apparatus which does not use such a metal material is proposed (for example, refer patent document 2). However, in the force detection device disclosed in Patent Document 2, it is possible to accurately evaluate the magnitude and direction of the force generated by the motion with two or more degrees of freedom mainly as a result of assuming the motion in one axis direction. There is a problem that is difficult.

  On the other hand, there are already some studies on how the brain is acting on limb movements.

  For example, the neural expression of the movement-related areas has been clarified mainly by electrophysiological experiments using monkeys (see, for example, Non-Patent Document 1). From such studies on monkeys, it has been found that the primary motor area expresses body movements in the muscle coordinate system.

  However, in monkey research, invasive measurement of the brain is used, and the number of parts that can be measured at one time is limited.

  For this reason, it is not clear what kind of coordinate system (head center, muscle, joint, etc.) the limb movement information is expressed when a human moves limbs. is there.

  By the way, in the case of humans, it is necessary to measure brain activity non-invasively. In this case, a decoding technique capable of extracting more detailed information from fMRI data has been developed (for example, see Non-Patent Document 2). ).

Japanese Unexamined Patent Publication No. 2011-000184 Japanese Patent Application Laid-Open No. 2003-284699

Kakei S, Hoffman DS, Strick PL, Muscles and movement representations in the primary motor cortex.Science 285: 2136-2139 (1999) Kamitani Y, Tong F. Decoding the visual and subjective contents of the human brain. Nat Neurosci. 2005; 8: 679-85.

  The brain activity measurement device such as an MRI device expresses limb movement information in any coordinate system (head center, muscle, joint, etc.) of the brain in a device that measures the activity of the human body, especially the brain. In order to investigate whether or not the limbs move in multiple axes, it is necessary to be able to measure brain activity. In other words, it is necessary to be able to measure the force and direction generated by the movement of the human limb with a higher degree of freedom.

  In particular, when the brain activity measurement device is a device that measures brain activity by magnetic field measurement, the force detection device is also required not to interfere with such magnetic field measurement.

  The present invention has been made to solve the above-described problems, and its purpose is to measure the direction and magnitude of a force generated by a motion of a subject having multiple degrees of freedom. It is to provide a possible multi-axial force detection device.

  Another object of the present invention is to provide a force detection device that does not interfere with magnetic field measurement when detecting force and direction in the motion of a subject in a device that measures brain activity by magnetic field measurement. That is.

  Still another object of the present invention is to provide a brain activity of a subject by magnetic measurement in a state where the subject is performing a task using a multi-axis direction force detection device capable of measuring the direction and magnitude of the force. It is providing the brain activity measuring apparatus which can measure this.

  According to one aspect of the present invention, there is provided a multi-axial force detection device for detecting a force from a subject with respect to an exercise task given to the subject during measurement of the skull portion of the subject in the brain activity measurement device. A fixed base, an action part that receives a force from the subject, and a load cell part that is fixed at one end to the fixed base and has an action part at the other end in the longitudinal direction, the load cell part extending in the longitudinal direction. And a first parallel plate portion formed by a side surface portion of a first through hole that penetrates and opens the elastic member in a first direction orthogonal to the longitudinal direction, and is orthogonal to the first direction. A second parallel flat plate portion formed by a side surface portion of the second through hole that opens through the elastic member in the second direction, and a first for detecting the deformation amount of the first parallel flat plate portion. Change of gauge and second parallel plate part And a second gauge for detecting the amount.

  Preferably, the brain activity measuring apparatus is a nuclear magnetic resonance imaging apparatus, and the fixed base, the action part, and the load cell part are formed of a nonmagnetic material.

  Preferably, the action part has a surface that receives the force applied by the subject and is detachable from the load cell part, and the direction of the surface can be changed to either the horizontal direction or the vertical direction by detaching the action part. The fixing base is provided with a hole into which the elastic member can be inserted on the side where the load cell part is fixed, and the load cell part is fixed to the fixing base by inserting the elastic member into the hole.

  Preferably, a plurality of holes are provided, and the calibration member is inserted into another of the plurality of holes in a state where the elastic member is inserted and fixed in a predetermined hole of the plurality of holes. The calibration member further includes a pulley that is rotatably supported by the calibration member, and calibrates by suspending a weight of a predetermined weight by a string member from the action unit via the pulley during calibration. Execute.

  Preferably, each of the first and second gauges irradiates light from the optical fiber onto the parallel plate at a predetermined angle via the first lens, receives the reflected light via the second lens, and reflects the reflected light. The amount of deformation of the parallel plate is detected from the change in the light receiving state.

  Preferably, the elastic member includes a first elastic part fixed to the fixing base, and the first elastic part includes a pair of leg members each having one end fixed to the fixing base and a pair of leg parts. And a second elastic part that protrudes from the central part of the support member and that has an action part at the other end in the longitudinal direction. The first and second parallel flat plate portions are The load cell portion is formed in the elastic portion, and the third and fourth through-holes opened on both sides sandwiching the central portion of the support member are connected to the third direction orthogonal to both the first direction and the second direction. Third and fourth parallel plate portions for detecting the deformation of the support member in the direction, and third and fourth gauges for detecting the deformation amounts of the third and fourth parallel plate portions, respectively. In addition.

  According to another aspect of the present invention, there is provided a brain activity measuring device for displaying an instruction of a movement direction in a movement task for moving one of a subject's joints isometrically in a direction in at least a predetermined two-dimensional plane. A display device, a brain activity measuring device for non-invasively measuring the brain activity of the subject and identifying an active brain region, and a motor task during measurement of the skull of the subject in the brain activity measuring device A multi-axis force detection device for detecting the magnitude and direction of the force applied by the subject, a force trajectory during movement detected by the multi-axis direction force detection device, And a storage device for storing the brain activity information in association with each other, and the display device presents the trajectory of the force during exercise to the subject during the exercise task.

  Preferably, the force detection device includes a fixed base, an action portion that receives a force by the subject, and a load cell portion that is fixed at one end to the fixed stand and has an action portion at the other end in the longitudinal direction. Is a first parallel flat plate portion formed by an elastic member extending in the longitudinal direction and a side surface portion of a first through hole that opens through the elastic member in a first direction orthogonal to the longitudinal direction; The amount of deformation of the second parallel plate portion formed by the side surface portion of the second through hole that penetrates and opens the elastic member in the second direction orthogonal to the first direction, and the amount of deformation of the first parallel plate portion A first gauge for detection and a second gauge for detecting the deformation amount of the second parallel plate portion are included.

  Preferably, the brain activity measuring apparatus is a nuclear magnetic resonance imaging apparatus, and the fixed base, the action part, and the load cell part are formed of a nonmagnetic material.

  Preferably, the elastic member has a rectangular cross-sectional shape, the action portion has a surface that receives a force applied by the subject, and the fixing base has a force from the subject on the side on which the load cell portion is fixed. A hole into which the elastic member can be inserted is provided regardless of whether the receiving direction is the direction along the first direction or the direction along the second direction, and the load cell portion is fixed by inserting the elastic member into the hole. Fixed to the base.

  According to the force detection device of the present invention, the load cell can detect the direction and magnitude of the force applied to the grip portion in the multiaxial direction.

  Further, according to the present invention, in an apparatus for measuring brain activity by magnetic field measurement, interference is not given to magnetic field measurement when detecting force and direction of the subject's movement.

  Alternatively, according to the brain activity measuring device of the present invention, the subject's brain activity is measured by magnetic measurement in a state where the subject is performing the task using the multi-axis direction force detection device. Brain activity can be observed on the spot.

1 is a schematic diagram showing an overall configuration of an MRI apparatus 10. 1 is an external view showing an external configuration of an MRI apparatus 10. 1 is an external view of a configuration of a biaxial force detection device 100 according to a first embodiment. FIG. 4 is an enlarged view of a portion including a second through hole 122 and a second gauge 132. It is a conceptual diagram for demonstrating how a distortion | strain arises in a parallel plate type dynamometer. It is a figure which shows the external appearance of the jig | tool 200 used for a calibration. It is a figure for demonstrating the calibration using the jig | tool 200. FIG. It is a conceptual diagram for demonstrating the principle at the time of making the test subject 2 perform a subject using the force detection apparatus 100, and measuring brain activity. It is a figure for demonstrating the time passage of the subject which the test subject 2 performs. It is a figure which shows the detection result of the coordinate system about the brain activity site | part measured by fMRI, and a primary motor area. 6 is an external view of a configuration of a triaxial force detection device 300 according to Embodiment 2. FIG.

Hereinafter, the configuration of a multi-axis force detection device according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, components and processing steps given the same reference numerals are the same or equivalent, and the description thereof will not be repeated unless necessary.
[Embodiment 1]
Hereinafter, an MRI apparatus will be described as an example of an apparatus for measuring the brain activity of a subject. However, the multi-axis direction force detection apparatus according to the present embodiment can be used not only for brain activity measurement by the MRI apparatus but also for brain activity measurement by another apparatus. In particular, when the multi-axis direction force detection device is formed of a non-magnetic material, in a device that measures brain activity by magnetic field measurement, the magnitude and direction of the subject's movement force is detected. Is preferred.

  FIG. 1 is a schematic diagram showing the overall configuration of the MRI apparatus 10.

  As shown in FIG. 1, the MRI apparatus 10 includes a magnetic field application mechanism 11 that applies a controlled magnetic field to a region of interest of the subject 2 and irradiates an RF wave, and a response wave (NMR) from the subject 2. Signal) and output an analog signal, a drive unit 21 that controls the magnetic field applied to the subject 2 and controls transmission and reception of RF waves, and a control sequence of the drive unit 21. And a data processing unit 32 configured to set and process various data signals to generate an image.

  Here, the central axis of the cylindrical bore on which the subject 2 is placed is taken as the Z axis, and the X axis in the horizontal direction perpendicular to the Z axis and the Y axis in the vertical direction are defined.

  Since the MRI apparatus 10 has such a configuration, the nuclear spin of the nuclei constituting the subject 2 is oriented in the magnetic field direction (Z-axis) by the static magnetic field applied by the magnetic field applying mechanism 11, and this Precession is performed around this magnetic field direction at the Larmor frequency specific to the nucleus.

  When an RF pulse having the same frequency as that of the Larmor frequency is irradiated, the atoms resonate and absorb energy to be excited, and a nuclear magnetic resonance phenomenon (NMR phenomenon; Nuclear Magnetic Resonance) occurs. When the RF pulse irradiation is stopped after this resonance, the atoms emit an electromagnetic wave (NMR signal) having the same frequency as the Larmor frequency in a relaxation process in which energy is released and returns to the original steady state.

  The output NMR signal is received by the receiving coil 20 as a response wave from the subject 2, and the region of interest of the subject 2 is imaged in the data processing unit 32.

  The magnetic field application mechanism 11 includes a static magnetic field generation coil 12, a gradient magnetic field generation coil 14, an RF irradiation unit 16, and a bed 18 for placing the subject 2 in the bore.

  Next to the subject 2, a multi-axis force detection device (hereinafter simply referred to as “force detection device”) 100 fixed to the bed 18 is provided. Although the subject 2 is not particularly limited, for example, the prism glasses 4 can see the screen displayed on the display 6 installed perpendicular to the Z axis. A visual stimulus is given to the subject 2 by the image on the display 6.

  Note that the visual stimulus to the subject 2 may be configured such that an image is projected by a projector in front of the subject 2.

  The drive unit 21 includes a static magnetic field power source 22, a gradient magnetic field power source 24, a signal transmission unit 26, a signal reception unit 28, a bed driving unit 30 that moves the bed 18 to an arbitrary position in the Z-axis direction, and a force detection device. And a sensor controller 50 that controls 100 and detects force.

  The data processing unit 32 receives various operations and information input from an operator (not shown), a display unit 38 that displays various images and various information related to the region of interest of the subject 2, and various processes. Controls the operation of each functional unit such as a storage unit 36 for storing programs to be executed, control parameters, image data (three-dimensional model image, etc.) and other electronic data, and generating a control sequence for driving the drive unit 21. An interface unit 44 that executes transmission and reception of various signals between the control unit 42 and the drive unit 21, a data collection unit 46 that collects data including a group of NMR signals derived from the region of interest, and data of the NMR signals And an image processing unit 48 for forming an image based on the above.

  The data processing unit 32 is a general-purpose computer that executes a function for operating each functional unit, in addition to the case of being a dedicated computer, and based on a program installed in the storage unit 36, a specified calculation or data This includes cases where processing and control sequences are generated.

  The static magnetic field generating coil 12 generates an induction magnetic field by causing a current supplied from a static magnetic field power supply 22 to flow through a spiral coil wound around the Z axis, and generates a static magnetic field in the Z axis direction in the bore. . The region of interest of the subject 2 is set in a region where the static magnetic field formed in the bore is highly uniform. Here, more specifically, the static magnetic field coil 12 is composed of, for example, four air-core coils, and a combination thereof creates a uniform magnetic field inside the predetermined magnetic nucleus in the body of the subject 2, more specifically, Gives orientation to the spin of hydrogen nuclei.

The gradient magnetic field generating coil 14 includes an X coil, a Y coil, and a Z coil (not shown), and is provided on the inner peripheral surface of the static magnetic field generating coil 12 having a cylindrical shape.
These X coil, Y coil, and Z coil superimpose a gradient magnetic field on the uniform magnetic field in the bore while sequentially switching the X-axis direction, the Y-axis direction, and the Z-axis direction, and give an intensity gradient to the static magnetic field. . During excitation, the Z coil limits the resonance surface by inclining the magnetic field strength in the Z direction, and the Y coil adds a short time immediately after applying the magnetic field in the Z direction to phase-modulate the detection signal in proportion to the Y coordinate. Is added (phase encoding), and the X coil subsequently applies a gradient when data is acquired to give the detected signal a frequency modulation proportional to the X coordinate (frequency encoding).

  Switching of the superimposed gradient magnetic field is realized by outputting different pulse signals from the transmitter 24 to the X coil, the Y coil, and the Z coil in accordance with the control sequence. Thereby, the position of the subject 2 where the NMR phenomenon appears can be specified, and position information on three-dimensional coordinates necessary for forming the image of the subject 2 is given.

The RF irradiation unit 16 irradiates the region of interest of the subject 2 with an RF (Radio Frequency) pulse based on the high-frequency signal transmitted from the signal transmission unit 33 according to the control sequence.
The RF irradiation unit 16 is built in the magnetic field application mechanism 11 in FIG. 1, but may be provided on the bed 18 or integrated with the receiving coil 20.

The receiving coil 20 detects a response wave (NMR signal) from the subject 2 and is disposed close to the subject 2 in order to detect the NMR signal with high sensitivity.
Here, when the electromagnetic wave of the NMR signal cuts the coil wire in the receiving coil 20, a weak current is generated based on the electromagnetic induction. The weak current is amplified by the signal receiving unit 28, further converted from an analog signal to a digital signal, and sent to the data processing unit 32.

  That is, when a high-frequency electromagnetic field having a resonance frequency is applied to the subject 2 in a state where a Z-axis gradient magnetic field is added to the static magnetic field through the RF irradiating unit 16, a predetermined portion of the portion where the magnetic field strength is in the resonance condition is applied. Nuclei, such as hydrogen nuclei, are selectively excited and begin to resonate. Predetermined nuclei in a portion that matches the resonance condition (for example, a tomography having a predetermined thickness of the subject 2) are excited, and spins rotate together. When the excitation pulse is stopped, the electromagnetic wave emitted by the rotating spin is induced in the receiving coil 20 this time, and this signal is detected for a while. By this signal, a tissue containing a predetermined atom in the body of the subject 2 is observed. And in order to know the transmission position of a signal, it is the structure of adding a gradient magnetic field of X and Y, and detecting a signal.

  The image processing unit 48 measures the detection signal while repeatedly applying the excitation signal based on the data constructed in the storage unit 36, and reduces the resonance frequency to the X coordinate by the first Fourier transform calculation. The Y coordinate is restored by Fourier transformation to obtain an image, and an image corresponding to the display unit 38 is displayed.

  FIG. 2 is an external view showing an external configuration of the MRI apparatus 10.

  In FIG. 2, the force detection device 100 is fixed to the bed 18. The method of fixing the force detection device 100 in this way is not particularly limited. For example, a resin plate is fixed on the surface of the bed 18 on which the subject 2 lies, and the force detection device 100 is non-magnetic on the plate. It is possible to take a method of fixing by a fixing tool such as a resin bolt and nut.

  In the drawing, the force detection device 100 is fixed to the right hand side of the subject 2 in the bed 18, but is not limited to this configuration, and is fixed to the left hand side of the subject 2 in the bed 18. May be.

(Configuration of the biaxial force detection device 100)
Hereinafter, as the first embodiment, a configuration of a force detection device 100 capable of detecting a force in two axial directions will be described.

  FIG. 3 is an external view of the configuration of such a biaxial force detection device 100.

  As described in detail later, the subject 2 displays the problem of moving the wrist in a predetermined direction in the XY plane in FIG. 3 when the brain activity is detected by measuring the skull portion by fMRI. 6 is instructed. The force detection device 100 detects the magnitude and direction of the force applied by the subject 2 when the subject 2 moves one wrist in the indicated direction.

  The force detection device 100 includes a fixed base 102, a grip portion 104 that the subject 2 grips, and a load cell portion 110 that is fixed at one end to the fixed base 102 and has the grip portion 104 at the other end in the Z direction, which is the longitudinal direction. Is provided.

  The load cell portion 110 has a rectangular cross-sectional shape, and is formed by an elastic member 112 extending in the longitudinal direction and a side portion of the first through hole 120 that opens through the elastic member 112 in the X direction orthogonal to the longitudinal direction. The first parallel flat plate portion 121, the second parallel flat plate portion 123 formed by the side surface portion of the second through hole 122 that opens through the elastic member 112 in the Y direction, and the first parallel flat plate A first gauge 130 for detecting the deformation amount of the portion 121 and a second gauge 132 for detecting the deformation amount of the second parallel flat plate portion 123 are included.

  In addition, as a material of the fixing base 102, the elastic member 112, and the grip part 104, an elastic material having a predetermined rigidity can be used, and is not particularly limited, but a nonmagnetic material such as a so-called “engineering plastic” can be used. It is possible to use a resin. More specifically, for example, a polyacetal resin can be used as such an engineering plastic. Alternatively, as long as the magnetic field measurement is not affected, the nonmagnetic material is not limited to such a resin, and may be a nonmagnetic metal such as aluminum.

  Here, the grip portion 104 is configured to be detachable from the load cell portion 110, and is fixed to the load cell portion 110 with a non-magnetic material, for example, a resin screw (not shown) during measurement. Has been. And the holding part 104 is a structure which can change the direction of a handle (handle) to either a horizontal direction (Y direction) or a vertical direction (X direction) by changing the direction inserted in the load cell part 110. And In FIG. 3, the grip portion 104 is inserted into the load cell portion 110 so that the handle is in the vertical direction (X direction).

  In FIG. 3, the through hole 120 and the through hole 122 are described as holes having a rectangular cross section, but are not necessarily limited to such a shape. In the elastic member 112 that is a strain generating body, if the side surfaces of the through hole 120 and the through hole 122 can be used as a “parallel plate type force meter (parallel plate type load cell)”, the cross-sectional shape of the hole is The shape may also be Therefore, for example, the thickness of the member of the parallel plate portion does not necessarily have to be uniform.

  FIG. 4 is an enlarged view of a portion including the second through hole 122 and the second gauge 132 in FIG. 3.

  The part including the first through hole 120 and the first gauge 130 is basically the same in configuration.

  FIG. 5 is a conceptual diagram for explaining how strain occurs in a parallel plate force meter.

  Below, the structure and operation | movement as a load cell of the parallel plate part 123 are demonstrated according to FIG. 4 and FIG.

  First, referring to FIG. 4, the second gauge 132 is opposed to one side surface of the parallel plate portion 123 on the mounting portion 124 that protrudes from the elastic member 112 so as to be L-shaped in cross section by integral molding. To be attached. The second gauge 132 detects a change in the distance δ between itself and one side surface of the parallel plate portion 123.

  Although not particularly limited, the second gauge 132 may be an optical displacement sensor, for example, a limited reflection type LED (Light Emitting Diode) type optical fiber displacement sensor. Here, for example, in the case of an optical fiber displacement sensor of the limited reflection method, when one side surface of the parallel plate 123 is irradiated at a predetermined angle with the light of the LED from the optical fiber 126 via the first lens (projecting lens). The reflected light of the reflection component is received via the second lens (light receiving lens). Since the light intensity received and transmitted via the fiber 126 changes according to the displacement of the distance δ, the amount of displacement of the distance to the object can be known by detecting the change in the light reception intensity. From this displacement amount, the X-direction component of the force applied to the load cell can be detected. Due to such a configuration, it is possible to detect the amount of displacement without using a magnetic material in the second gauge 132 portion. In addition, since signal transmission is performed by an optical fiber, noise is not mixed into the signal even in a room where the MRI apparatus is installed.

  Similarly, the Y direction component of the force applied to the load cell can be detected independently of the X direction by the parallel plate portion 121 and the first gauge 130.

  In other words, the parallel plate portion 121 and the parallel plate portion 123 can detect the magnitude and direction of the force in the XY plane applied to the load cell.

  As such an optical sensor, for example, a resin fiber unit composed of a transmission / reception fiber and a lens, for example, FU-38 manufactured by KEYENCE can be used.

  Since the optical sensor of this embodiment is not a system in which thin optical fibers are installed facing each other, it has a feature that there is a margin in accuracy required for alignment and that it is easy to manufacture.

  The second gauge 132 is attached to the mounting portion 124 as described above, and the portion where the mounting portion 124 continues to the elastic member 112 is outside the parallel plate portion 123 (opening of the through hole 122). Therefore, the attachment of the second gauge 132 does not interfere with the deformation of the parallel plate portion 123.

  In general, in a parallel plate type force meter, a strain gauge is used to measure the amount of deformation. However, a general strain gauge has a structure in which a metal resistor (metal foil) laid out in a zigzag shape is attached to a thin insulator, and by measuring the change in electrical resistance due to deformation, “Converted into strain amount”. Since the strain gauge metal resistor has magnetism, it is not necessarily suitable for performing an accurate measurement in an MRI apparatus that uses a strong magnetic field. However, in the present embodiment, as described above, since the change in the distance δ is optically detected, even in the magnetic field, the change in the distance δ is detected with high accuracy without affecting the measurement. It is possible to detect the magnitude and direction of the force in the XY plane applied to the load cell.

  Referring to FIG. 5, the width of the parallel plate (in the depth direction of the screen in FIG. 5) is b, the thickness of the parallel plate is t, the length of the parallel plate is I, the applied force is F, When the longitudinal elastic modulus of the parallel plate is E, the displacement δ is expressed as follows.

δ = FI ³ / (2 Ebt ³ )
Therefore, conversely, the force F can be obtained from the displacement δ.

(Calibration of force detection device 100)
Hereinafter, an example of the calibration method of the force detection device 100 described above will be described.

  FIG. 6 is a diagram showing the appearance of the jig 200 used for calibration.

  As shown in FIG. 6, the jig 200 is supported by the elastic member 210 having the same cross-sectional shape as the force detection device 1002 elastic member 112, a support member 220 attached to the tip of the elastic member 210, and the support member 220. And a pulley 230.

  As shown in FIG. 6, the elastic member 210 is bent in the middle so that the root side and the tip side are displaced in parallel. Further, the support member 220 is provided with a gap 240 from the back surface thereof toward the upper side of the pulley 230.

  Here, it is desirable that both the elastic member 210 and the pulley 230 are made of a nonmagnetic material.

  FIG. 7 is a diagram for explaining calibration using the jig 200.

  First, the fixed base 102 is fixed on the base 3 installed so that the upper surface is horizontal.

  In addition, in the fixed base 102, holes 103-1 to 103-9 that are just large enough to fit the elastic member 112 on the side where the elastic member 112 is attached are arranged in 3 × 3. . However, the number of holes is not limited to nine.

  In the arrangement of the holes 103-1 to 103-9 as described above, the elastic member 112 of the load cell portion 110 is inserted and fixed in the middle hole 103-5 so that the handle of the grip portion 104 is in the vertical direction. ing.

  Further, the elastic member 210 of the jig 200 is inserted and fixed in the hole 103-4 having the same height as the load cell unit 110.

  In this state, the string 250 that suspends the weight 260 is connected to the handle of the grip portion 104 through the gap via the pulley 230. Again, it is desirable that both the weight 260 itself and the string 250 are made of a non-magnetic material.

  With such a configuration, the force detection device 100 itself, the jig 200 used for calibration, the weight 260, and the string 250 can all be made of a nonmagnetic material, In that case, the calibration can be performed in the room where the NMR apparatus is installed without affecting the measurement of the NMR apparatus, and the calibration accuracy and thus the measurement accuracy can be improved. It becomes possible to execute efficiently.

  Since the weight of the weight 260 is known in advance, the load cell can be calibrated by applying a predetermined force in the Y direction (horizontal direction) to the handle of the grip portion 104 with the configuration shown in FIG. it can.

  In the calibration for applying a predetermined force in the X direction (vertical direction) to the handle of the grip portion 104, for example, the grip portion 104 is loosened and the grip portion 104 is removed from the load cell portion 110. Fit the handle in the horizontal direction and fix it. At this time, the load cell portion 110 remains inserted into the hole 103-5. On that basis, the jig 200 is inserted into a hole 103-2 vertically above the hole 103-5 of the fixing base 102 and fixed, with the jig rotated by 90 degrees in the direction of the pulley. Then, the string 250 having one end tied to the handle of the grip portion 104 is suspended from the other end of the string 250 via a pulley positioned vertically above the handle, and the same as in the Y direction. Calibration can be performed.

  In FIG. 6, the pulley 230 is fixed so as to be rotatable in a direction orthogonal to the longitudinal direction of the elastic member 210, assuming calibration in the Y direction. Although not particularly limited, the pulley 230 can be attached to and detached from the support member 220, and when calibrating in the X direction, the pulley 230 is positioned in the gap 240 and the pulley 230 is rotatable in the longitudinal direction. The support part 220 may have a structure in which a groove capable of fitting the pulley 230 is formed. That is, when the groove is provided so as to form a cross with the gap 240 when the support member 220 is viewed from the opening side of the gap 240, the pulley 230 is inserted into the groove, as described above. It can be set as a simple structure. In this case, even in the calibration in the X direction, the calibration can be executed using the same jig 200 as in the calibration in the Y direction.

  In addition, a plurality of holes as described above are provided on the fixing base 102 at different heights, and the load cell is fixed by inserting the elastic member 112 into the holes. The height can be easily adjusted. In addition, since the grip 104 is detachably fixed from the load cell portion 110 with a fixing tool, the handle direction of the grip 104 can be easily changed to either the X direction or the Y direction even when measuring force. can do.

(Measurement procedure)
FIG. 8 is a conceptual diagram for explaining the principle when the subject 2 is caused to execute a task using the force detection device 100 and the brain activity is measured.

  That is, in the following, in order to examine the coordinate expression of the brain in the movement of the limbs, a case where the movement in a plurality of directions and the brain activity at that time are measured will be described as an example.

  Such a method corresponds to that performed by Kakei et al.

  First, as shown in FIG. 8A, the direction of motion is defined as 0 ° and 180 ° in the horizontal direction, and the direction of motion instructed by the subject 2 is eight directions of 45 °.

  Then, the subject 2 is asked to mainly perform isometric exercise (isometric exercise) after holding the handle of the grip 104 of the force detection device 100 in the pronation and supination positions. The reason for the isometric motion is that the variation in motion can be suppressed.

  In this state, subject 2 performs tasks such as wrist extension and flexion.

  The most important feature of this movement task is that the coordinate system of neuronal activity can be distinguished by separating the three coordinate systems of space, joints and muscles related to wrist movement. Since details of coordinate system separation are disclosed in Non-Patent Document 1, only an outline will be briefly described below.

  Here, the “coordinate system” means a method of taking a reference for describing a motion.

  For example, “upper” and “lower” are descriptions of movements based on an external space, and are called a spatial coordinate system. On the other hand, “extension” and “flexion” are motion descriptions based on the wrist joint structure, and are called joint coordinate systems.

  Then, subject 2 performs wrist movements in eight directions with different postures of pronation and supination. For example, suppose that a certain brain region is most profoundly active in the pronation and moving up. This alone cannot distinguish whether the activity of the brain region expresses the “up” direction in the spatial coordinate system or the “extension” of the wrist in the joint coordinate system.

  Therefore, the wrist is rotated 180 degrees to the swivel position. If the activity of the brain region means “up”, it is again activated by movement to “up” (however, the wrist is bent), and is identified as a spatial coordinate system. If it means “extension” of the wrist, it is determined to be a joint coordinate system that is still active in the “extension” movement (but the wrist moves downward). Furthermore, the coordinate system of the muscles that move when moving the wrist is changed to the spatial coordinate system by changing the wrist direction during exercise, such as “pronunciation” → “intermediate” → “extraversion”. It is also shown that it is distinguished from the joint coordinate system.

  FIG. 9 is a diagram for explaining the time course of the task performed by the subject 2.

  Referring to FIG. 9, subject 2 is asked to perform an exercise task according to the visual stimulus displayed on display 6, and the brain activity change at that time is imaged.

  That is, a fixed viewpoint is displayed at the center of the display 6 and the direction of movement is instructed. In response to this, the trajectory of force in the exercise performed by the subject 2 (change in time in magnitude and direction) is displayed.

  As described above, the exercise task is exercise of the wrist, and the subject is caused to move the wrist in a plurality of different directions (direction 1, direction 2,...).

  Although not particularly limited, for example, subject 2 is asked to perform isotonic exercise and isometric exercise. In the isotonic exercise task, the movement of the upper limb is measured by optical motion capture. In the isometric exercise task, the exercise output (force direction and magnitude) is measured using the force detection device 100.

  Furthermore, in order to investigate the coordinate expression of the movement-related cortex, the posture of the upper limb is changed and the movement task is performed. A cuff can also be used to suppress incidental movements of a part (elbow or shoulder) that is not the body part (wrist) of interest. In order to suppress variation in the movement of the subject for each trial, the subject 2 is fed back as a visual stimulus by displaying the movement trajectory or the movement output on the display 6 as a trajectory that can recognize the passage of time. The muscle output during exercise is measured with an electromyograph, and the eye movement is measured with an eye movement monitor.

  The imaging information of the brain activity change thus measured is stored in the storage unit 36 by the control unit 42 in association with the instruction direction of the exercise task and the exercise output information.

  In the analysis of the measurement data, first, the cortical structure of each subject is divided into a primary motor area, a premotor area, a supplementary motor area, etc. according to the form. Next, the direction of motion is decoded in each of these areas. In addition, it investigates how the decoding result changes when moving from one posture to another, and clarifies the coordinate representation of the motion in each region.

  FIG. 10 is a diagram showing the detection results of the coordinate system for the brain activity site and the primary motor area measured by fMRI in this way.

  As shown in FIG. 10A, the brain region that is active during right wrist movement is measured by fMRI.

  FIG. 10 (b) shows a preliminary experimental result. In the decoding result from the primary motor area, there is a possibility that two expressions of spatial coordinates and muscle coordinates are mixed in the right wrist movement. It shows that there is.

  As described above, by adopting a configuration like the force detection device 100, the load cell 110 has a magnitude and direction in the XY plane of the force applied to the grip portion 104, that is, in other words, the force X component and Y component can be detected. In addition, since the force detection device 100 is made of a nonmagnetic material, brain activity during exercise can be measured by a device that measures brain activity by magnetic field measurement, such as an MRI device.

Therefore, in a device that measures brain activity by detecting a magnetic field like an MRI device, it is possible to measure not only the coordinates in the motor cortex for human motion but also various other brain activities during human motion. It becomes.
[Embodiment 2]
Hereinafter, as a second embodiment, a configuration of a force detection device 300 that can detect forces in three axial directions will be described.

  In addition, the same code | symbol is attached | subjected to the part which is the same as that of the force detection apparatus 100 of Embodiment 1, or a corresponding part.

  FIG. 11 is an external view of the configuration of the triaxial force detection device 300 according to the second embodiment.

  As will be described in detail later, the subject 2 is instructed by the display 6 to display the task of moving the wrist in a predetermined three-dimensional direction when the brain activity is detected by measuring the skull by fMRI. . The force detection device 300 detects the magnitude and direction of the force applied by the subject 2 when the subject 2 moves one wrist in the designated direction.

  The force detection device 300 includes a fixed base 102, a grip portion 104 that the subject 2 grips, and a load cell portion 310.

  The load cell portion 310 includes a U-shaped first elastic portion 312 that is fixed to the fixed base 102. The first elastic portion 312 is integrally formed from leg members 312a and 312b whose one ends are fixed to the fixing base 102, and a support member 312c that connects the leg members 312a and 312b. The cross section of the first elastic portion 312 has a rectangular shape.

  The load cell portion 310 further includes a second elastic portion 110 that protrudes from the center of the support member 312c and is provided with the grip portion 104 at the other end in the longitudinal direction (Z direction).

  The second elastic portion 110 has a rectangular cross-sectional shape, an elastic member 112 extending in the longitudinal direction (Z direction), and a first penetration that opens through the elastic member 130 in the X direction orthogonal to the longitudinal direction. A first parallel flat plate portion 121 formed by the side surface portion of the hole 120 and a second parallel flat plate portion 123 formed by the side surface portion of the second through hole 122 that opens through the elastic member 112 in the Y direction. And a first gauge 130 for detecting the amount of deformation of the first parallel flat plate portion 121 and a second gauge 132 for detecting the amount of deformation of the second parallel flat plate portion 123.

  The first elastic part 312 and the second elastic part 110 can be integrally formed of resin.

  In the support portion 312c, the support member 312c passes through the support member 312c in the Y direction between the central portion connected to one end of the elastic member 112 and the leg member 312a and between the central portion and the portion connected to the leg member 312b. A third parallel plate portion 321 formed by the side surface portion of the third through hole 320 that opens and a side portion of the fourth through hole 322 that opens through the support member 312c in the Y direction. 4 parallel plate portions 323, a third gauge 330 for detecting the deformation amount of the third parallel plate portion 321, and a fourth gauge 332 for detecting the deformation amount of the fourth parallel plate portion 323. And are provided.

  As the configurations of the first to fourth gauges 130, 132, 330, and 332, the optical displacement sensor as described in the first embodiment can be used.

  Although not particularly limited, so-called “engineering plastic” can be used as the material of the fixing base 102, the first elastic portion 312 and the second elastic portion 110, and the grip portion 104. More specifically, For example, a polyacetal resin can be used.

  Also, in FIG. 11, the through hole 120, the through hole 122, the through hole 320, and the through hole 322 are described as holes having a rectangular cross section, but are not necessarily limited to such a shape. . In the first elastic part 312 and the second elastic part 110 which are the strain generating bodies, the side surfaces of the through hole 120, the through hole 122, the through hole 320 and the through hole 322 are “parallel plate type force meters (parallel plate type). As long as it can be used as a shape load cell), the cross-sectional shape of the hole may be another shape.

  Also in the force detection device 300 of the second embodiment, the elastic member 312 can be fitted just on the side where the elastic member 312 is attached to the fixed base 102 so that the calibration jig can be used. It is assumed that the holes having a size are arranged in n × m (n and m are natural numbers of 3 or more, respectively).

  In the arrangement of the holes as described above, the elastic member 312 is fixed by inserting the leg portions into the two holes so that the handle of the grip portion 104 is in the vertical direction. By arranging the holes provided in the fixing base 102 in n × m, it becomes easy to change the height of the grip portion 104 and to fix it, as in the first embodiment. Furthermore, since the grip 104 is detachably fixed to the load cell portion 310 by a fixing tool as in the first embodiment, the handle 104 of the grip 104 is fixed by changing the direction of the handle from the vertical direction to the horizontal direction and calibrating. Or force measurement becomes easier.

  Further, the elastic member 210 of the jig 200 is inserted into a hole different from the load cell portion 310 and fixed. Since the calibration method is basically the same as that of the first embodiment, detailed description thereof is omitted.

  By configuring the force detection device 300 as described above, the force detection device 300 has a load cell 310 and the magnitude and direction of the force applied to the grip portion 104 in the XY plane, that is, In other words, not only the X and Y components of the force can be detected, but also the Z component of the force can be detected. Further, since the force detection device 300 is made of a nonmagnetic material, the brain activity during exercise can be measured by a device that measures brain activity by magnetic field measurement, such as an MRI device.

  Therefore, in addition to the effects exhibited by the force detection device according to the first embodiment, the force detection device according to the second embodiment can also measure various other brain activities during human exercise.

  In the above description of the first embodiment or the second embodiment, the exercise task given to the subject 2 is a wrist exercise, but the present invention is not necessarily limited to such a case. For example, the movement may be an ankle movement, a movement of an arm joint, a movement of a leg joint, or a movement of a specific joint of a finger of a hand, for example. Therefore, in the above description, the part gripped by the hand of the subject 2 is referred to as a “gripping part”, and the handle (handle) of the gripping part includes a surface that receives the action of force from the subject 2. In this way, when not limited to wrist movement, a portion including a surface that receives the action of force from the subject 2 is more generally referred to as an “action portion”. By changing the size of the action part and the rigidity and size of the load cell part according to the range of the magnitude of the force to be measured and the size of the place to move, this is a more general exercise task , It is possible to detect the magnitude and direction of the force from the subject.

  Embodiment disclosed this time is an illustration of the structure for implementing this invention concretely, Comprising: The technical scope of this invention is not restrict | limited. The technical scope of the present invention is shown not by the description of the embodiment but by the scope of the claims, and includes modifications within the wording and equivalent meanings of the scope of the claims. Is intended.

  2 subjects, 6 display, 10 MRI apparatus, 11 magnetic field application mechanism, 12 static magnetic field generation coil, 14 gradient magnetic field generation coil, 16 RF irradiation unit, 18 bed, 20 reception coil, 21 drive unit, 22 static magnetic field power source, 24 gradient Magnetic field power supply, 26 signal transmission unit, 28 signal reception unit, 30 bed driving unit, 32 data processing unit, 36 storage unit, 38 display unit, 40 input unit, 42 control unit, 44 interface unit, 46 data collection unit, 48 image Processing unit, 50 sensor controller unit, 100 force detection device, 102 fixing base, 104 gripping unit, 110 load cell unit, 112 elastic member, 120 first through hole, 121 first parallel plate portion, 122 second through hole 123 Second parallel plate portion, 130 First gauge, 132 Second gauge 132, 300 Force test Deposition device, 310 load cell section, 312 first elastic section, 312a, 312b leg member, 312c support member, 320 third through hole, 321 third parallel flat plate portion, 322 fourth through hole, 323 fourth Parallel plate portion, 330 third gauge, 332 fourth gauge 332.

Claims (9)

A multi-axis force detection device for detecting a force from a subject for a motion task given to the subject during measurement of the skull portion of the subject in the brain activity measurement device,
A fixed base;
An action part that receives force by the subject;
One end side is fixed to the fixed base, and the load cell portion is provided with the action portion at the other end in the longitudinal direction.
An elastic member extending in the longitudinal direction;
A first parallel flat plate portion formed by a side surface portion of a first through hole that opens through the elastic member in a first direction orthogonal to the longitudinal direction;
A second parallel flat plate portion formed by a side surface portion of a second through hole that opens through the elastic member in a second direction orthogonal to the first direction;
A first gauge for detecting a deformation amount of the first parallel plate portion;
And a second gauge for detecting the amount of deformation of the second parallel flat plate portion. The brain activity measuring device is a nuclear magnetic resonance imaging device,
The multi-axis direction force detection device according to claim 1, wherein the fixed base, the action portion, and the load cell portion are formed of a nonmagnetic material. The action part has a surface that receives a force applied by the subject and is detachable from the load cell part. The direction of the surface is either horizontal or vertical depending on the attachment / detachment of the action part. Can be changed,
The fixing base is provided with a hole into which the elastic member can be inserted on the side where the load cell portion is fixed,
The multi-axial force detection device according to claim 1, wherein the load cell portion is fixed to the fixing base by inserting the elastic member into the hole. A plurality of the holes are provided,
A calibration member that is inserted into another of the plurality of holes in a state where the elastic member is inserted and fixed in a predetermined hole of the plurality of holes;
The calibration member includes a pulley that is rotatably supported by the calibration member;
The multi-axis direction force detection device according to claim 3, wherein calibration is performed by suspending a weight having a predetermined weight from the acting portion via the pulley and by a string member during calibration.   Each of the first and second gauges irradiates light from an optical fiber to the parallel plate at a predetermined angle via a first lens, receives reflected light via a second lens, and transmits the reflected light. The multi-axis direction force detection device according to claim 1, wherein a deformation amount of the parallel plate is detected based on a change in a light receiving state. The elastic member is
Including a first elastic portion fixed to the fixed base;
The first elastic part is
A set of leg members each having one end fixed to the fixed base;
A support member connecting the pair of legs,
A second elastic portion that protrudes from the central portion of the support member and that has an action portion provided at the other end in the longitudinal direction;
The first and second parallel flat plate portions are formed on the second elastic portion,
The load cell unit is
Deformation of the support member in a third direction orthogonal to both the first direction and the second direction by third and fourth through holes opening on both sides sandwiching the central portion of the support member Third and fourth parallel plate portions for detecting
3. The multi-axial force detection device according to claim 1, further comprising third and fourth gauges for detecting deformation amounts of the third and fourth parallel plate portions, respectively. A display device for displaying an instruction of a movement direction in a movement task for moving one of the joints of the subject in an isometric direction at least in a predetermined two-dimensional plane;
A brain activity measuring device for non-invasively measuring the brain activity of the subject and identifying an active brain region;
A multiaxial force detection device for detecting the magnitude and direction of force applied by the subject when performing the exercise task during measurement of the skull portion of the subject in the brain activity measurement device;
A storage device for storing the trajectory of the force during exercise detected by the multi-axis direction force detection device and the brain activity information during the exercise in association with each other;
The display device is a brain activity measurement device that presents a trajectory of force during the exercise to the subject during execution of an exercise task. The force detection device includes:
A fixed base;
An action part that receives force by the subject;
One end side is fixed to the fixed base, and the load cell portion is provided with the action portion at the other end in the longitudinal direction.
An elastic member extending in the longitudinal direction;
A first parallel flat plate portion formed by a side surface portion of a first through hole that opens through the elastic member in a first direction orthogonal to the longitudinal direction;
A second parallel flat plate portion formed by a side surface portion of a second through hole that opens through the elastic member in a second direction orthogonal to the first direction;
A first gauge for detecting a deformation amount of the first parallel plate portion;
The brain activity measuring device according to claim 7, further comprising a second gauge for detecting a deformation amount of the second parallel plate portion. The brain activity measuring device is a nuclear magnetic resonance imaging device,
The brain activity measuring device according to claim 8, wherein the fixed base, the action portion, and the load cell portion are formed of a nonmagnetic material.