JP6143443B2 - Sensor - Google Patents

Description

  The present invention relates to a magnetic force sensor that detects a change in magnetic flux caused by a relative displacement between a magnetic flux generation source and a magnetoelectric transducer and converts it into force and moment components.

  The force sensor is composed of a maximum of six axes of forces Fx, Fy, Fz in the translational direction of each axis and moments Mx, My, Mz in the rotation direction of each axis in the three-dimensional coordinate space of the X, Y, and Z axes. And a sensor for detecting moments. This force sensor is attached to, for example, a wrist portion of an industrial robot hand, detects a force and a moment generated in the assembling work, and can correct the assembling work operation according to the detected value.

  As the force sensor, various types of force sensors such as a strain gauge type, a capacitance type, and a magnetic type are known depending on applications. Among these, the magnetic force sensor has a simple configuration and can be manufactured at low cost, and is expected to be used in various applications. However, the magnetic sensor has a problem of multi-axis interference due to its detection principle (= for example, it occurs when it is displaced in the vertical direction due to the influence of the gradient of the magnetic field in spite of receiving an external force that is displaced only in the horizontal direction. Because there was a phenomenon in which output changes also appeared), it was difficult to detect the output of each axis independently with high accuracy, so the application was limited.

  Therefore, in order to solve this problem of other-axis interference, the magnetic force sensor described in Japanese Patent Application Laid-Open No. 2011-145286 (Patent Document 1) has magnetic pole surfaces of adjacent magnets that are opposite to each other in a specific direction. The magnetic flux generation source is composed of two or more magnets arranged to be.

  The acting portion to which the external force acts is provided between the first magnetoelectric conversion element and the first magnetoelectric conversion element respectively provided at positions facing the magnetic pole surface of the magnet so that the magnetic pole surfaces are opposite to each other. And a magnetoelectric conversion element. The force of the vertical direction component is detected based on the output of the first magnetoelectric conversion element, and the force of the horizontal direction component is detected based on the output of the second magnetoelectric conversion element.

  Thus, the problem of the multi-axis interference of the magnetic force sensor is solved by independently detecting the force of the vertical component and the force of the horizontal component.

JP 2011-145286 A

  When the magnetic force sensor having such a configuration is used, it is necessary to adjust the relative position between the magnetoelectric transducer and the magnetic flux generation source and calibrate in advance. However, Patent Document 1 does not specifically describe a mechanism that is easy for a user to calibrate.

An object of the present invention is to provide a magnetic force sensor that can easily adjust the relative position between a magnetoelectric transducer and a magnetic flux generation source.
The sensor of the present invention includes a base , a support member that is an annular frame, a working portion that is formed from the center in four directions toward the support member, and a plurality of parts that connect the base and the support member. A sensing unit comprising: a column of the first electrode; a substrate fixed to the action unit; a first magnetoelectric conversion element and a second magnetoelectric conversion element fixed to the substrate; and a magnetic flux generation source held by a holder; The sensing part is formed between the base and each of the action parts formed in the four directions, and the holder is installed on the base so as to be movable. The position of the magnetic flux generation source relative to the first magnetoelectric conversion element and the second magnetoelectric conversion element is changed by the movement of the holder.

  The present invention can provide a magnetic force sensor that can easily adjust the relative position between a magnetoelectric transducer and a magnetic flux generation source.

It is a perspective view of a magnetic type force sensor. FIG. 4 is a schematic perspective view showing an arrangement of a magnetoelectric conversion element and a magnetic flux generation source on a horizontal plane (on an XY plane). It is the figure which showed the specific structure of the position adjustment part. It is a figure which shows other embodiment. It is an enlarged view of sensing. It is a figure which best represents the detection principle of a magnetic force sensor. It is the block diagram which showed the flow of the output of the 6-axis force sensor which concerns on this invention.

  A magnetic force sensor will be described with reference to the accompanying drawings. Hereinafter, the force and the moment may be collectively referred to as “force”.

  FIG. 6A is one of the drawings showing the detection principle of the magnetic force sensor, and is a schematic perspective view of the sensing unit of the magnetic force sensor. In the present invention, the magnetoelectric transducer and magnetic flux generation source related to force sensing are collectively referred to as a sensing unit. The sensing unit functions to detect the relative position between the action unit 4 and the magnetic flux generation source 7 described below by converting the detected magnetic field into an electrical signal. The sensing unit includes first magnetoelectric conversion elements 1a to 1d arranged opposite to the magnetic pole surface of the magnet, second magnetoelectric conversion elements 2a to 2d arranged between the first magnetoelectric conversion elements, and 3a. -3d has four magnets 3a-3d constituting a magnetic flux generation source. The magnets 3a to 3d are arranged so that the N pole and the S pole are opposite to each other in the Z-axis direction.

  The magnetic flux generation source 7 should just be comprised from the 2 or more magnet arrange | positioned so that the magnetic pole surface of an adjacent magnet may become mutually opposite, and the magnet which comprises the magnetic flux generation source 7 needs to be four Absent. Moreover, the number of sensing units is not necessarily one, and a plurality of sensing units may be provided in one sensor.

  Furthermore, the number of arranged magnetoelectric transducers does not necessarily have to be as described above, and the user of the magnetic force sensor according to the present invention may appropriately select it according to desired accuracy.

  FIG. 6B is a cross-sectional view taken along the X axis-Z axis of the magnetic force sensor having the sensing unit of FIG. The sensing unit is housed in a cylindrical housing K.

  The magnetic force sensor includes an action portion 4 on which an external force acts, an elastic body 5 having a function of converting the force applied by the force applied to the action portion 4 and converting the force into a displacement, the magnetoelectric conversion element 1, and the magnetoelectric conversion. It has the board | substrate 6 with which the element 2 is mounted, and the magnetic flux generation source 7 comprised from a some magnet. The magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 mounted on the substrate 6 are fixed to the action part 4 via the substrate 6. The action part 4 is supported by an elastic body 5. Furthermore, it has the conversion part, the calculating part, and the memory | storage part which A / D convert the output of the magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 which were distribute | arranged to the board | substrate 6. FIG. The conversion unit, calculation unit, and storage unit will be described later again.

  The magnetic flux generation source 7 is composed of two or more magnets 3 having a pair of N pole and S pole. The magnetic flux generation source 7 may form a pattern formed by connecting a plurality of magnets to one magnetic flux generation source. In short, what is necessary is just to be comprised so that the direction of the magnetic field which generate | occur | produces from a magnet may be reversed on the boundary of the adjacent magnet.

  The magnet 3 and the magnetic flux generation source 7 may be permanent magnets such as Nd—Fe—B magnets, Sm—Co magnets, Sm—Fe—N magnets, and ferrite magnets. Alternatively, an electromagnet that generates a magnetic force by winding and energizing a coil may be used. The magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are a Hall element, an MR element, a magnetic impedance element, a fluxgate element, or a wound coil.

  When the action part 4 receives a force Fx in the X-axis direction, a force Fy in the Y-axis direction, and a moment Mz in the Z-axis direction, the magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are horizontal (on the X axis-Y axis plane). To be relatively displaced with respect to the magnetic flux generation source 7. On the other hand, when the action part 4 receives the moment Mx in the X-axis direction, the moment My in the Y-axis direction, and the force Fz in the Z-axis direction, the magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are moved in the vertical direction (Z axis-X axis). Or it is displaced relatively on the Z-axis-Y-axis plane). The magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 detect a change in magnetic flux density passing through the magnetoelectric conversion element caused by this displacement, and convert it into a force and a moment.

That is, the magnetic flux generation source includes at least a first magnet and a second magnet, and the first magnetoelectric conversion element A is disposed to face the central portion of the magnetic pole surface of the first magnet. ing. The first magnetic pole of the magnetic pole surface of the first magnet and the second magnetic pole of the magnetic pole surface of the second magnet are adjacent to each other,
The first magnetic pole and the second magnetic pole have opposite polarities, and the second magnetoelectric conversion element A is arranged facing the boundary between the first magnet and the second magnet.

  FIG. 6C is an elevational view when viewed from the side surface of the sensing unit shown in FIG. 6A, and also shows the generated magnetic lines of force. In FIG. 6C, two magnets 3 are arranged, and adjacent magnets 3 have opposite polarities with respect to the Z-axis orientation. The magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are arranged so as to face the magnetic pole surface of the magnet 3, and are arranged so as to detect the Z-axis direction component of the magnetic field, respectively. The first magnetoelectric conversion element 1 has a large change in the magnetic flux density of the Z-axis direction component of the magnetic field flowing with respect to the displacement in the Z-axis direction, but the Z-axis direction of the flowing magnetic field with respect to the displacement in the X-axis direction. The change in the magnetic flux density of the component is small. On the other hand, the second magnetoelectric transducer 2 has a large change in the magnetic flux density of the Z-axis direction component of the incoming magnetic field with respect to the displacement in the X-axis direction, but the incoming magnetic field does not change with respect to the Z-axis direction displacement. The change in the magnetic flux density of the Z-axis direction component is small.

  Next, the flow of the output of the 6-axis magnetic force sensor according to the present invention is shown for the principle of detecting the 6-axis force and moment by the magnetic flux generation source composed of 2 × 2 magnets 3a to 3d. This will be described with reference to FIG. 7 which is a block diagram.

[Detection of vertical direction components Fz, Mx, My]
In order to calculate the vertical direction components Fz, Mx, My, the magnetic field of the vertical direction component detected by the first magnetoelectric transducers 1a to 1d arranged to face the center of the magnetic pole surface of the magnet is used. The output change caused by the displacement of the first magnetoelectric transducer 1a is amplified by the signal amplifying unit 8 and detected as V1a using the converter 9 having an A / D converter. Similarly, the first magnetoelectric conversion elements 1b to 1d are also detected as V1b to V1d.

Fz = V1a + V1b + V1c + V1d
Mx = (V1a + V1b) − (V1c + V1d)
My = (V1b + V1c) − (V1a + V1d)
Fz, Mx, My are calculated by the calculation unit 10 as described above. Fz is calculated from the total change amount of the four elements, Mx is calculated from the change amount of two pairs of elements arranged parallel to the X-axis direction, and My is an element arranged parallel to the Y-axis direction. It is calculated from the amount of change between two pairs.

[Detection of horizontal direction components Fx, Fy, Mz]
In order to calculate the horizontal direction components Fx, Fy, and Mz, the magnetic field of the horizontal direction component detected by the second magnetoelectric conversion elements 2a to 2d respectively disposed between the first magnetoelectric conversion elements is used. An output change caused by the displacement of the second magnetoelectric conversion element 2a is amplified by the signal amplifier 8, and detected as V2a using the converter 9 having an A / D converter. Similarly, the magnetoelectric conversion elements 2b to 2d are also detected as V2b to V2d.

Fx = V2b−V2d
Fy = V2a-V2c
Mz = V1a + V1b + V1c + V1d
Fx, Fy, and Mz are calculated by the calculation unit 10 as described above. Fx is calculated from the amount of change of a pair of elements arranged perpendicular to the X direction, Fy is calculated from the amount of change of a pair of elements arranged perpendicular to the Y direction, and Mz is a total change of four elements. Calculate by quantity.

  As described above, the four first magnetoelectric transducers arranged respectively facing the magnetic pole surfaces of the 2 × 2 magnets detect the force of the vertical component, and between the first magnetoelectric transducers The force of the horizontal component is detected by four second magnetoelectric transducers arranged respectively. Accordingly, it is possible to provide a 6-axis magnetic force sensor that reduces other-axis interference between the horizontal component and the vertical component.

  That is, the external force applied to the action part is determined based on the value of the output of the first magnetoelectric transducer A by the magnetic force sensor based on the magnetic pole surface of the first magnet and the magnetic pole surface of the second magnet. The axial force is detected by the detector. At the same time, based on the output value of the second magnetoelectric transducer A, the detection unit detects the force in the Y-axis direction and the force in the X-axis direction based on the magnetic pole surface of the first magnet and the magnetic pole surface of the second magnet. Detect with.

[Position adjustment section]
Hereinafter, the position adjusting unit, which is a feature of the present embodiment, will be specifically described with reference to the drawings.

  FIG. 1 is a perspective view of the magnetic force sensor described above. The magnetic force sensor includes a housing K composed of a plurality of columnar structures, and the action portion 4 cuts a cross with respect to the elastic body 5 as a support member having an annular frame. It is formed with beams. A substrate 6 is fixed to the action part 4, and the magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are mounted on the substrate 6. The magnetoelectric conversion element 1 and the magnetoelectric conversion element 2 are disposed at a position facing the magnetic flux generation source 7 having a plurality of magnets placed on a holder.

FIG. 2 is a schematic perspective view showing the arrangement of the magnetoelectric conversion element and the magnetic flux generation source 7 on the horizontal plane (on the X-axis-Y-axis plane). FIG. 2 shows the arrangement of the magnetic force sensor when the action portion side is viewed from above, with the action portion side being upward, and the beam portion of the action portion 4 is drawn in a cross shape with broken lines.
FIG. 3 shows a configuration in which four sensing units each including a magnetic flux generation source 7 including two magnets, a first magnetoelectric conversion element, and a second magnetoelectric conversion element are provided.

  When the force applied in the horizontal direction and the force applied in the vertical direction are detected independently, the first magnetoelectric conversion element and the second magnetoelectric conversion element are predetermined with respect to the magnetic flux generation source 7 as described above. It is necessary to be arranged in the position.

  FIG. 3 is a diagram illustrating a specific configuration of the position adjustment unit. Sensing units each having a magnetic flux generation source 7 and a magnetoelectric conversion element are arranged vertically and horizontally on the paper surface. For the sake of explanation, a part of the sensing part of the left hand is drawn with a perspective image of a part of the member for explanation.

  A description will be given below on behalf of a well-sensing sensing unit. The magnetic flux generation source 7a is fixed to the holder, and is fixed to the holder by screwing with a bolt provided on the side surface of the holder. The holder is installed so as to be displaceable in a horizontal direction (X-axis direction) with respect to the paper surface with respect to a guide provided on a base having a rod-shaped member.

  And the screw hole which lets a fixing screw pass is provided in the holder, and the fixing screw is inserted in the base provided with the long hole which took the length with respect to the slidable direction. When the fixing screw is loosened, the holder becomes movable with respect to the base in the longitudinal direction of the long hole, and when the fixing screw is tightened, the position is fixed with respect to the base. On the other hand, the positions of the first magnetoelectric conversion element and the second magnetoelectric conversion element are fixed to the action part 4 via the substrate. By adopting such a configuration, the facing position of the magnetic flux generation source 7 can be relatively adjusted with respect to the magnetoelectric transducer.

  The holders may be composed of a single member so that the holders can have a plurality of magnetic flux generation sources 7 and can be held together, but the holders are provided independently so that they can be individually adjusted by each sensing unit. Is preferred.

  FIG. 4 is a diagram showing another embodiment.

  The same members as those described above are denoted by the same reference numerals and description thereof is omitted. Compared to the above-described example, a difference is that a rotation axis is provided instead of a slide. The holder holding the magnetic flux generation source 7 is held so as to be rotatable with respect to a rotating shaft provided at the center of the base. The longitudinal direction of the long hole into which the fixing screw is inserted is formed along the direction of rotation. By taking such a configuration, the position of the magnetic flux generation source 7 can be adjusted relative to the magnetoelectric transducer. In the case where the distance from the rotation center to the position where the magnetic flux generation source is disposed is larger than the distance between the first magnetoelectric conversion element and the second magnetoelectric conversion element, such a configuration has a simple structure. Is preferred.

  FIG. 5 is an enlarged view of the upper sensing unit shown in FIG.

  The distance L from the rotation axis to the center of gravity of the magnetic flux generation source 7 is 15.5 mm, and the length of one side of the magnet is 5 mm. When detecting the force, a change in the relative position between the magnetic flux generation source 7 and the magnetoelectric conversion element in a range of ± 50 μm from the reference position is detected via a change in the magnetic field flowing into the magnetoelectric conversion element. Therefore, it is sufficient that the longitudinal length of the long hole is about 200 μm = 0.2 mm.

  In other words, assuming that ΔX = 0.2 mm is displaced in the X-axis direction around the rotation axis, this displacement is much smaller than the distance L, so that it can be approximated as ΔY≈0.2 / 15.5 mm = 0.013 mm. Therefore, since the displacement of the long hole for adjustment is hardly displaced in the Y-axis direction, the position adjustment can be executed with sufficient accuracy.

  The present invention can be suitably used as a force sensor for detecting force.

DESCRIPTION OF SYMBOLS 1 (1a-1d) 1st magnetoelectric conversion element 2 (2a-2d) 2nd magnetoelectric conversion element 3 (3a-3d) Magnet 4 Action part 5 Elastic body 6 Magnetoelectric conversion element mounting board 7 Magnetic flux generation source 8 Signal amplification part 9 Conversion unit 10 Calculation unit

Claims (4)

The base,
A support member that is an annular frame;
An action part formed toward the support member in four directions from the center;
A plurality of pillars connecting the base and the support member;
A substrate fixed to the action part;
A sensing unit including a first magnetoelectric conversion element and a second magnetoelectric conversion element fixed to the substrate, and a magnetic flux generation source held by a holder;
Have
The sensing part is formed between the base and each of the action parts formed in the four directions,
The holder is installed on the base so as to be movable,
The position of the magnetic flux generation source with respect to the first magnetoelectric conversion element and the second magnetoelectric conversion element is changed by the movement of the holder.   2. A long hole provided in the base and a fixing screw provided in the holder, or a fixing screw provided in the base and a long hole provided in the holder. The sensor described.   The sensor according to claim 1, further comprising a base on which a rotating shaft is provided for mounting the holder and rotatably supporting the holder. Obtaining the force in the Z-axis direction based on the output value of the first magnetoelectric conversion element, and obtaining the force in the Y-axis direction and the force in the X-axis direction based on the output value of the second magnetoelectric conversion element. The sensor according to any one of claims 1 to 3 .

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