US20150276513A1 - Sensor element, force detecting device, robot and sensor device - Google Patents
Sensor element, force detecting device, robot and sensor device Download PDFInfo
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- US20150276513A1 US20150276513A1 US14/722,248 US201514722248A US2015276513A1 US 20150276513 A1 US20150276513 A1 US 20150276513A1 US 201514722248 A US201514722248 A US 201514722248A US 2015276513 A1 US2015276513 A1 US 2015276513A1
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- 239000000758 substrate Substances 0.000 claims abstract description 135
- 239000013078 crystal Substances 0.000 claims abstract description 58
- 230000003287 optical effect Effects 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 13
- 229910000154 gallium phosphate Inorganic materials 0.000 claims description 6
- LWFNJDOYCSNXDO-UHFFFAOYSA-K gallium;phosphate Chemical compound [Ga+3].[O-]P([O-])([O-])=O LWFNJDOYCSNXDO-UHFFFAOYSA-K 0.000 claims description 6
- RIUWBIIVUYSTCN-UHFFFAOYSA-N trilithium borate Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-] RIUWBIIVUYSTCN-UHFFFAOYSA-N 0.000 claims description 6
- 229910003327 LiNbO3 Inorganic materials 0.000 claims description 3
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims 2
- 229910052744 lithium Inorganic materials 0.000 claims 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 80
- 239000011034 rock crystal Substances 0.000 description 76
- 238000001514 detection method Methods 0.000 description 30
- 238000005452 bending Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 239000010453 quartz Substances 0.000 description 4
- ORQBXQOJMQIAOY-UHFFFAOYSA-N nobelium Chemical compound [No] ORQBXQOJMQIAOY-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
- B25J19/02—Sensing devices
- B25J19/028—Piezoresistive or piezoelectric sensing devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
- G01L1/162—Measuring force or stress, in general using properties of piezoelectric devices using piezoelectric resonators
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
- G01L5/167—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using piezoelectric means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
- G01L5/226—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping
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- H01L41/1132—
-
- H01L41/1873—
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
- H10N30/302—Sensors
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
- H10N30/8542—Alkali metal based oxides, e.g. lithium, sodium or potassium niobates
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S901/00—Robots
- Y10S901/46—Sensing device
Definitions
- the present invention relates to a sensor element, a force detecting device and a robot.
- JP-A-4-231827 discloses a known force sensor using a piezoelectric material. As shown in FIG. 15 of JP-A-4-231827 plural measuring elements are arranged on the force sensor. Each measuring element includes a signal electrode 15 held between crystal disks 16. The crystal disks 16 are made of a piezoelectric material and are covered with a metal cover disk 17 .
- JP-A-4-231827 discloses the use of quartz, which suggests rock crystal, as a piezoelectric material, and maintains that quartz is an optimum material for measuring a multiple-component motive force since quartz receives both compressive and shear stress according to the crystal cut of the quartz.
- quartz which suggests rock crystal
- quartz is an optimum material for measuring a multiple-component motive force since quartz receives both compressive and shear stress according to the crystal cut of the quartz.
- quartz receives both compressive and shear stress according to the crystal cut of the quartz.
- An advantage of some aspects of the invention is to provide a sensor element which can detect a force with high sensitivity by finding a condition of use of a piezoelectric material that enables the generation of more electric charge in response to an external force, a sensor device and a force detecting device using this sensor element, and a robot with high reliability and safety having this force detecting device.
- This application example is directed to a sensor element including a piezoelectric substrate made of a trigonal single crystal, a first electrode arranged on one substrate surface of the piezoelectric substrate, and a second electrode arranged on the other substrate surface.
- the substrate surface of the piezoelectric substrate includes an X-axis (electrical axis) of crystal axes.
- An angle ⁇ formed by the substrate surface and a plane including the X-axis (electrical axis) and a Z-axis (optical axis) of the crystal axes is 0° ⁇ 20°.
- the amount of electric charge generated by a shear force applied to the piezoelectric substrate can be increased and a sensor element with high detection capability can be provided.
- This application example is directed to the above application example, wherein a portion of an outer surface that intersects the substrate surface of the piezoelectric substrate includes a plane extending in the X-axis direction.
- the plane of the site where a large strain is generated by a shear force applied to the piezoelectric substrate extends in the direction of the shear force. Therefore, a site where a large amount of electric charge is generated can be formed on the piezoelectric substrate and a sensor element with high detection capability can be provided.
- This application example is directed to a sensor element including a piezoelectric substrate made of a trigonal single crystal, a first electrode arranged on one substrate surface of the piezoelectric substrate, and a second electrode arranged on the other substrate surface.
- the substrate surface of the piezoelectric substrate has crystal axes including a Y-axis (mechanical axis) and a Z-axis (optical axis).
- a portion of an outer surface intersecting the substrate surface includes a plane.
- An angle ⁇ formed by the plane of the outer surface and a plane including an X-axis (electrical axis) and the Z-axis (optical axis) of the crystal axes is 25° ⁇ 85°.
- a site where a large strain is generated by a compressive force applied to the piezoelectric substrate extends to an outer part of the piezoelectric substrate and therefore an electric charge generation site area where more electric charge is generated by an increase in the strain is broadened.
- a sensor element with high detection capability can be provided.
- This application example is directed to the above application example, where the single crystal is a rock crystal.
- a rock crystal substrate as the piezoelectric substrate, a large amount of electric charge can be generated even with a very small strain and a sensor element with high detection capability can be provided. Moreover, a single crystal can be easily obtained and a piezoelectric substrate with excellent workability and quality stability can be formed. Thus, a sensor element capable of stable detection can be provided.
- This application example is directed to a force detecting device including the above sensor element, and an arithmetic unit which detects an amount of electric charge induced in the first electrode or the second electrode and calculates a force applied to the sensor element.
- a triaxial force detecting device can be provided with a simple configuration. Also, by using plural such triaxial force detecting devices, for example, a six-axis force detecting device including torque measuring can be easily provided.
- This application example is directed to a robot including the above sensor element, and an arithmetic unit which detects an amount of electric charge induced in the first electrode or the second electrode and calculates a force applied to the sensor element.
- a contact with an obstacle and a contacting force to an object during a predetermined operation of a robot arm or robot hand that make differential movements are securely detected by a force detecting device and data is fed back to a robot control device.
- a robot capable of performing safe and fine work can be provided.
- FIGS. 1A to 1C show a sensor element according to a first embodiment.
- FIG. 1A is a sectional view.
- FIG. 1B is an exploded perspective view.
- FIG. 1C is a view from the direction of an arrow A in FIG. 1B .
- FIG. 2 is a schematic view showing a method for forming a rock crystal substrate according to the first embodiment in relation to crystal axes X, Y, and Z.
- FIGS. 3A to 3C show a sensor element according to a second embodiment.
- FIG. 3A is a sectional view.
- FIG. 3B is an exploded perspective view.
- FIG. 3C is a view from the direction of an arrow B in FIG. 2B .
- FIG. 4 is a schematic view showing a method for forming a rock crystal substrate according to the second embodiment in relation to crystal axes X, Y, and Z.
- FIGS. 5A and 5B are plan views showing other forms of the rock crystal substrate according to the second embodiment.
- FIG. 6 is a sectional view showing a sensor device according to a third embodiment.
- FIGS. 7A to 7C show sensor devices as other forms of the third embodiment.
- FIG. 7A is a sectional view.
- FIGS. 7B and 7C are exploded perspective views.
- FIGS. 8A and 8B show a force detecting device according to a fourth embodiment.
- FIG. 8A is a sectional view.
- FIG. 8B is a conceptual view showing the arrangement of sensor devices.
- FIGS. 9A and 9B show another force detecting device according to the fourth embodiment.
- FIG. 9A is a plan view.
- FIG. 9B is a sectional view taken along C-C′ in FIG. 9A .
- FIG. 10 shows the configuration of a robot according to a fifth embodiment.
- FIGS. 11A and 11B are graphs showing examples of implementation.
- FIG. 11A shows an example of implementation of the sensor element according to the first embodiment.
- FIG. 11B shows an example of implementation of the sensor element according to the second embodiment.
- FIGS. 1A to 1C show a sensor element according to a first embodiment.
- FIG. 1A is a sectional view.
- FIG. 1B is an exploded perspective view.
- FIG. 1C is a view from the direction of an arrow A in FIG. 1B .
- a sensor element 100 shown in FIGS. 1A to 1C includes a rock crystal substrate 10 as a piezoelectric substrate, a detection electrode 20 as a first electrode, and a grounding electrode (hereinafter referred to as GND electrode) 30 as a second electrode.
- the material of the piezoelectric substrate is not limited to rock crystal as long as the material is a trigonal single crystal.
- a trigonal single crystal refers to a crystal which has crystal axes such that three symmetry axes with equal lengths intersect each other at an angle of 120°, with one vertical axis meeting the point of intersection.
- trigonal single crystals include langasite (La 3 Ga 5 SiO 14 ), lithium niobate (LiNbO 3 ) single crystal, lithium tantalate (LiTaO 3 ) single crystal, gallium phosphate (GaPO 4 ) single crystal, lithium borate (Li 2 B 4 O 7 ) single crystal and the like.
- a rock crystal which can generate a large amount of electric charge even with a very small strain and can easily provide a single crystal and also has excellent workability and quality stability is used.
- the detection electrode 20 is arranged on one substrate surface 10 a of the rock crystal substrate 10
- the GND electrode 30 is arranged on the other substrate surface 10 b .
- the rock crystal substrate 10 is held between the detection electrode 20 and the GND electrode 30 . That is, in terms of the illustrated coordinate axes ⁇ , ⁇ , ⁇ , the detection electrode 20 , the rock crystal substrate 10 and the GND electrode 30 are stacked in this order in the ⁇ direction, thus forming the sensor element 100 . If a force F ⁇ in a shear direction along the illustrated ⁇ -axis direction is applied to the sensor element 100 , the rock crystal substrate 10 is deformed into a shape like a deformed rock crystal substrate 10 ′. With the strain due to this deformation, electric charge is generated in the rock crystal substrate 10 .
- the rock crystal substrate 10 is made of a so-called Y-cut plate in which a plane intersecting the Y-axis as the mechanical axis of the crystal axes and including the X-axis as the electrical axis constitutes a main surface
- the deformation shown in FIG. 1A that is, the strain that causes the deformation into the rock crystal substrate 10 ′ is generated
- positive (+) electric charge is generated inside the rock crystal substrate 10 on the side of the one substrate surface 10 a of the rock crystal substrate 10 where the detection electrode 20 is arranged
- negative ( ⁇ ) electric charge is generated inside the rock crystal substrate 10 on the side of the other substrate surface 10 b where the GND electrode 30 is arranged.
- the ⁇ electric charge on the side of the other substrate surface 10 b is discharged to the ground (GND), not shown, by the GND electrode 30 .
- the + electric charge on the side of the one substrate surface 10 a is sent as a detection value to an arithmetic unit, not shown, by the detection electrode 20 . Based on the resulting amount of electric charge, the force F ⁇ in the ⁇ direction is calculated.
- the rock crystal substrate 10 made of a rock crystal that is a trigonal single crystal as a piezoelectric body, electric charge is generated as described above by an internal strain.
- the amount of this electric charge increases and decreases depending on the angle of the substrate surfaces 10 a , 10 b of the rock crystal substrate 10 to the crystal axes X, Y, Z.
- a larger amount of electric charge can be obtained particularly depending on the following forming conditions of the substrate surfaces 10 a , 10 b.
- FIG. 1C shows the rock crystal substrate 10 , as viewed from the direction of the arrow A shown in FIG. 1B along the ⁇ -axis.
- the rock crystal substrate 10 is sliced out with an angle ⁇ formed by the one substrate surface 10 a of the rock crystal substrate 10 and a plane defined by the Z-axis and X-axis.
- FIG. 2 schematically shows the method for forming the rock crystal substrate 10 in relation to the crystal axes X (electrical axis), Y (mechanical axis), Z (optical axis).
- the rock crystal substrate 10 is formed in such a way that an angle formed by a surface 1 a including the X-axis and Z-axis and orthogonal to the Y-axis, of a rock crystal body 1 sliced out along the crystal axes X, Y, Z, and the substrate surfaces 10 a , 10 b , within a plane defined by the Y-axis and Z-axis, becomes the angle ⁇ .
- the angle ⁇ may be preferably formed within a range of 0° ⁇ 20°.
- FIGS. 3A to 3C show a sensor element according to a second embodiment.
- FIG. 3A is a sectional view.
- FIG. 3B is an exploded perspective view.
- FIG. 3C is a view from the direction of an arrow B in FIG. 3B .
- a sensor element 200 according to the second embodiment is different in the form of the rock crystal substrate 10 from the sensor element 100 according to the first embodiment, and the other parts of the configuration are the same as the first embodiment. Therefore, the same parts of the configuration are denoted by the same reference numerals and will not be described further in detail. As shown in FIGS.
- the sensor element 200 according to the second embodiment is the sensor element 200 that detects a force F ⁇ in a direction in which a rock crystal substrate 40 is compressed, that is, in a ⁇ direction.
- the sensor element 200 has a configuration in which a detection electrode 20 as a first electrode, the rock crystal substrate 40 as a piezoelectric substrate, and a GND electrode 30 as a second electrode are stacked in the ⁇ direction.
- the material of the piezoelectric substrate is not limited to rock crystal as long as the material is a trigonal single crystal. However, also in this embodiment, an example in which a rock crystal is used as a piezoelectric material is described.
- the rock crystal substrate 40 is compressed and deformed into a shape like a rock crystal substrate 40 ′. With the strain due to this deformation, electric charge is generated in the rock crystal substrate 40 .
- the rock crystal substrate 40 is made of a so-called X-cut plate in which a plane intersecting the X-axis as the electrical axis of the crystal axes and including the Y-axis as the mechanical axis and the Z-axis as the optical axis constitutes a main surface. If the deformation shown in FIG.
- the rock crystal substrate 40 made of a rock crystal that is a trigonal single crystal as a piezoelectric body, electric charge is generated as described above by an internal strain.
- the amount of this electric charge increases and decreases depending on the angle formed by planes 40 c , 40 d forming a part of an outer surface intersecting the substrate surfaces 40 a , 40 b of the rock crystal substrate 40 and the surface defined by the X-axis and Z-axis.
- a larger amount of electric charge can be obtained particularly depending on the following forming conditions of the planes 40 c , 40 d.
- FIG. 3C shows a view from the direction of the arrow B shown in FIG. 3B .
- the outer surface forming the outer shape of the rock crystal substrate 40 includes at least one plane.
- the outer surface includes the planes 40 c , 40 d .
- the rock crystal substrate 40 is sliced out in such a way that the plane 40 d has an angle ⁇ relative to a plane defined by the X-axis and Y-axis of the crystal axes.
- the rock crystal substrate 40 is rectangular and the plane 40 c and the plane 40 d of the outer surface are substantially parallel to each other. Therefore, the rock crystal substrate 40 is sliced out in such a way that the plane 40 c , too, has an angle ⁇ relative to the plane defined by the X-axis and Y-axis of the crystal axes.
- FIG. 4 schematically shows the method for forming the rock crystal substrate 40 in relation to the crystal axes X, Y, Z.
- the rock crystal substrate 40 is formed in such a way that an angle formed by a surface 2 a defined by the X-axis and Z-axis of a rock crystal body 2 sliced out along the crystal axes X, Y, Z and the plane 40 d of the outer surface becomes the angle ⁇ .
- the plane 40 c is substantially parallel to the plane 40 d
- the rock crystal substrate 40 is formed in such a way that an angle formed by the surface 2 a and the plane 40 c becomes the angle ⁇ , too.
- the angle ⁇ may be preferably formed within a range of 25° ⁇ 85°.
- FIGS. 5A and 5B are views showing other forms of the rock crystal substrate 40 .
- the outer surface except the planes 40 c , 40 d is not limited to a plane. That is, as in a rock crystal substrate 41 shown in FIG. 5A , parts other than a plane 41 c or a plane 41 d intersecting the surface 2 a (see FIG.
- one plane 42 b may intersect the surface 2 a (see FIG. 4 ) defined by the X-axis and Z-axis, at the angle ⁇ , and the other parts of the surface may be a round surface 42 a or the like.
- FIG. 6 is a sectional view showing a sensor device according to a third embodiment.
- the sensor element 100 having the rock crystal substrate 10 or the sensor element 200 having the rock crystal substrate 40 is housed in a cylindrical container 400 and is pressed and fixed by bases 301 , 302 .
- the detection electrode 20 and the GND electrode 30 are electrically connected to an arithmetic unit 500 .
- the arithmetic unit 500 includes a QV amplifier, not shown, which converts the electric charge obtained by the detection electrode 20 , and also includes GND (ground) connected with the GND electrode 30 .
- the sensor device 1000 can easily detect a force applied between the base 301 and the base 302 .
- FIGS. 7A to 7C show sensor devices 1100 , 1200 as other forms of the third embodiment.
- FIG. 7A is a sectional view.
- FIG. 7B is an exploded perspective view of the sensor device 1100 .
- FIG. 7C is an exploded perspective view of the sensor device 1200 .
- the sensor devices 1100 , 1200 shown in FIGS. 7A to 7C have a configuration in which the rock crystal substrate 10 or the rock crystal substrate 40 as a piezoelectric substrate is arranged on both sides of the detection electrode 20 , compared with the above sensor device 1000 . That is, two sensor elements 100 or two sensor elements 200 are stacked, sharing the detection electrode 20 . As shown in FIG.
- a sensor element 101 and a sensor element 102 are arranged so as to share the detection electrode 20
- a sensor element 201 and a sensor element 202 are arranged so as to share the detection electrode 20 .
- the two sensor elements 101 , 102 or the sensor elements 201 , 202 , thus arranged, are housed in a cylindrical container 410 and pressed and fixed by the bases 301 , 302 .
- the detection electrode 20 and the GND electrode 30 are electrically connected to an arithmetic unit 510 .
- the arithmetic unit 510 includes a QV amplifier, not shown, which converts the electric charge obtained by the detection electrode 20 , and also includes GND (ground) connected with the GND electrode 30 .
- FIG. 7B shows the arrangement of the sensor elements 101 , 102 in the sensor device 1100 .
- the sensor element 101 and the sensor element 102 are stacked along an illustrated stacking direction N, with the ⁇ directions of the sensor elements aligned, as in the sensor element 100 according to the first embodiment.
- the sensor element 101 and the sensor element 102 are arranged so that the ⁇ directions and ⁇ directions of the sensor elements become opposite to each other so that electric charge of the same polarity is generated on the surface 10 a that contacts the detection electrode 20 , of the rock crystal substrate 10 on the upper side in the illustrated N direction, and on the surface 10 b of the rock crystal substrate 10 on the lower side in the illustrated N direction, when a force along an illustrated L direction is detected in the sensor device 1100 .
- FIG. 7C shows the arrangement of the sensor elements 201 , 202 in the sensor device 1200 .
- the sensor element 201 and the sensor element 202 are arranged with the sides of each sensor element reversed to each other, that is, so that the one substrate surface 40 a of the rock crystal substrate 40 contacts the detection electrode 20 .
- electric charge of the same polarity can be generated on the one substrate surface 40 a of the two rock crystal substrates 40 contacting the detection electrode 20 .
- FIGS. 8A and 8B show a force detecting device according to a fourth embodiment.
- FIG. 8A is a sectional view.
- FIG. 8B is a conceptual view showing the arrangement of sensor devices.
- a direction in which electrodes and rock crystal substrates are stacked (upward direction in FIG. 8A ) is defined as a V(+) direction.
- a rightward direction in FIG. 8A orthogonal to the V direction is an Hx(+) direction.
- a direction heading toward FIG. 8A from the viewer is an Hy(+) direction.
- electrodes and rock crystal substrates are alternately stacked within a cylindrical container 420 between a base 311 and a base 312 and are pressed and fixed by the base 311 and the base 312 .
- the electrodes and the rock crystal substrates housed in the cylindrical container 420 are stacked as follows. From the side of the base 311 , a sensor device 1101 in which sensor elements 101 , 102 are stacked in the same configuration as the sensor device 1100 according to the another form of the third embodiment, followed by a sensor device 1102 in which sensor elements 101 , 102 are stacked in the same configuration as the sensor device 1100 , and then a sensor device 1200 in which sensor elements 201 , 202 are stacked.
- the GND electrodes 30 except the GND electrode contacting the bases 311 , 312 are shared by the sensor devices 1101 , 1102 , 1200 .
- the arrangement of the sensor device 1102 is in a direction that results from rotating the sensor device 1101 by an angle of 90° about the V-axis. That is, the L-axis of the sensor device 1101 which detects a force along the L-axis is aligned with the Hx-axis, and the sensor device 1102 is arranged by rotating the L-axis by an angle of 90° about the V-axis and aligning the L-axis with the Hy-axis. Thus, forces along the Hx-axis and Hy-axis can be detected. Moreover, the sensor device 1200 which detects a force in the N-axis direction is arranged by aligning the N-axis with the V-axis. Thus, a force along the V-axis can be detected. In this manner, the force detecting device 2000 incorporating the sensor devices 1101 , 1102 , 1200 can detect forces in the Hx, Hy and V directions, that is, in triaxial directions.
- a force is applied to the bases 311 , 312 of the force detecting device 2000 thus configured, based on the electric charge generated in the sensor device 1101 , 1102 , 1200 , vector data of the applied external force including force components of Hx, Hy and V directions obtained by an Hx direction arithmetic unit 610 based on the electric charge of the sensor device 1101 , by an Hy direction arithmetic unit 620 based on the electric charge of the sensor device 1102 , and by a V direction arithmetic unit 630 based on the electric charge of the sensor device 1200 , are outputted to a control device, not shown, with the Hx, Hy and V direction arithmetic units 610 , 620 , 630 being provided in an arithmetic device 600 as an arithmetic unit.
- the electric charge excited in the GND electrode 30 is grounded and discharged by GND 640 provided in the arithmetic device 600 .
- the force detecting device 2000 can be a small-sized force detecting device by having electrodes and rock crystal substrates as piezoelectric substrates stacked in one direction. Also, the force detecting device of this embodiment can be formed by stacking electrodes and rock crystal substrates of simple shapes and therefore can be a low-cost force detecting device.
- FIGS. 9A and 9B schematically show a six-axis force detecting device 3000 which uses the force detecting device 2000 according to the above embodiment and is capable of torque detection.
- FIG. 9A is a plan view.
- FIG. 9B is a sectional view taken along C-C′ shown in FIG. 9A .
- the six-axis force detecting device 3000 has a configuration in which four force detecting devices 2000 are fixed by bases 321 , 322 .
- this six-axis force detecting device 3000 it is possible to find the torque about each of the Hx-axis, Hy-axis and V-axis based on the distance between the four force detecting devices 2000 that are arranged and the force obtained by each force detecting device 2000 .
- FIG. 10 is an external view showing the configuration of a robot 4000 using the force detecting device 2000 according to the third embodiment or the six-axis force detecting device 3000 .
- the robot 4000 includes a body portion 4100 , an arm portion 4200 , a robot hand portion 4300 and the like.
- the body portion 4100 is fixed, for example, on a floor, wall, ceiling, movable trolley or the like.
- the arm portion 4200 is provided movably in relation to the body portion 4100 .
- An actuator, not shown, which generates a motive force to rotate the arm portion 4200 , a control unit which controls the actuator, and the like are arranged inside the body portion 4100 .
- the arm portion 4200 includes a first frame 4210 , a second frame 4220 , a third frame 4230 , a fourth frame 4240 and a fifth frame 4250 .
- the first frame 4210 is connected to the body portion 4100 in a rotatable or bendable manner via a rotation-bending axis.
- the second frame 4220 is connected to the first frame 4210 and the third frame 4230 via a rotation-bending axis.
- the third frame 4230 is connected to the second frame 4220 and the fourth frame 4240 via a rotation-bending axis.
- the fourth frame 4240 is connected to the third frame 4230 and the fifth frame 4250 via a rotation-bending axis.
- the fifth frame 4250 is connected to the fourth frame 4240 via a rotation-bending axis.
- the arm portion 4200 operates as each of the frames 4210 to 4250 rotates or bends in a complex manner about each rotation-bending axis.
- the robot hand portion 4300 is attached on the side of the fifth frame 4250 of the arm portion 4200 that is opposite to the connecting part with the fourth frame 4240 .
- the robot hand portion 4300 includes a robot hand 4310 which can grip an object, and a robot hand connecting portion 4320 in which a motor to rotate the robot hand 4310 is arranged.
- the robot hand portion 4300 is connected to the fifth frame 4250 by the robot hand connecting portion 4320 .
- the force detecting device 2000 according to the third embodiment or the six-axis force detecting device 3000 is arranged in addition to the motor.
- the robot hand portion 4300 is moved to a predetermined operating position under the control of the control unit, contact with an obstacle or contact with an object in response to an operation command to exceed a predetermined position, or the like, can be detected as a force by the force detecting device 2000 or the six-axis force detecting device 3000 .
- This force can be fed back to the control unit of the robot 4000 so that an evasive action can be executed.
- a robot that can easily carry out an obstacle avoiding operation, an object damage avoiding operation and the like, which cannot be realized by traditional position control, and that can perform safe and fine work, can be provided.
- the technique is not limited to this embodiment and can also be applied to, for example, a two-arm robot.
- FIGS. 11A and 11B are graphs showing the amount of electric charge generated when a force is applied to the sensor element 100 according to the first embodiment and the sensor element 200 according to the second embodiment.
- the result of calculating the amount of electric charge in relation to the angle ⁇ in the case of the sensor element 100 is shown in FIG. 11A .
- the result of calculating the amount of electric charge in relation to the angle ⁇ in the case of the sensor element 200 is shown in FIG. 11B .
- the piezoelectric substrate is made of a rock crystal with a plane size of 5 mm by 5 mm and a thickness of 200 ⁇ m.
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Abstract
A sensor element includes a piezoelectric substrate made of a trigonal single crystal and an electrode arranged on the piezoelectric substrate. The substrate surface of the piezoelectric substrate includes an electrical axis of crystal axes. An angle θ formed by the substrate surface and a plane including the electrical axis and an optical axis of the crystal axes is 0°<θ<20°.
Description
- This is a continuation patent application of U.S. application Ser. No. 13/669,879 filed Nov. 6, 2012, which claims priority to Japanese Patent Application No. 2011-244208 filed Nov. 8, 2011 both of which are expressly incorporated by reference herein in their entireties.
- 1. Technical Field
- The present invention relates to a sensor element, a force detecting device and a robot.
- 2. Related Art
- JP-A-4-231827 discloses a known force sensor using a piezoelectric material. As shown in FIG. 15 of JP-A-4-231827 plural measuring elements are arranged on the force sensor. Each measuring element includes a signal electrode 15 held between crystal disks 16. The crystal disks 16 are made of a piezoelectric material and are covered with a metal cover disk 17.
- JP-A-4-231827 discloses the use of quartz, which suggests rock crystal, as a piezoelectric material, and maintains that quartz is an optimum material for measuring a multiple-component motive force since quartz receives both compressive and shear stress according to the crystal cut of the quartz. However, there is no description regarding the slicing of the piezoelectric material in a specific crystal direction.
- An advantage of some aspects of the invention is to provide a sensor element which can detect a force with high sensitivity by finding a condition of use of a piezoelectric material that enables the generation of more electric charge in response to an external force, a sensor device and a force detecting device using this sensor element, and a robot with high reliability and safety having this force detecting device.
- The invention can be implemented in the following forms or application examples.
- This application example is directed to a sensor element including a piezoelectric substrate made of a trigonal single crystal, a first electrode arranged on one substrate surface of the piezoelectric substrate, and a second electrode arranged on the other substrate surface. The substrate surface of the piezoelectric substrate includes an X-axis (electrical axis) of crystal axes. An angle θ formed by the substrate surface and a plane including the X-axis (electrical axis) and a Z-axis (optical axis) of the crystal axes is 0°<θ<20°.
- According to the sensor element of this application example, compared with the case where a so-called Y-cut plate with θ=0° is used as the piezoelectric substrate of the sensor element, the amount of electric charge generated by a shear force applied to the piezoelectric substrate can be increased and a sensor element with high detection capability can be provided.
- This application example is directed to the above application example, wherein a portion of an outer surface that intersects the substrate surface of the piezoelectric substrate includes a plane extending in the X-axis direction.
- According to this application example, the plane of the site where a large strain is generated by a shear force applied to the piezoelectric substrate extends in the direction of the shear force. Therefore, a site where a large amount of electric charge is generated can be formed on the piezoelectric substrate and a sensor element with high detection capability can be provided.
- This application example is directed to a sensor element including a piezoelectric substrate made of a trigonal single crystal, a first electrode arranged on one substrate surface of the piezoelectric substrate, and a second electrode arranged on the other substrate surface. The substrate surface of the piezoelectric substrate has crystal axes including a Y-axis (mechanical axis) and a Z-axis (optical axis). A portion of an outer surface intersecting the substrate surface includes a plane. An angle λ formed by the plane of the outer surface and a plane including an X-axis (electrical axis) and the Z-axis (optical axis) of the crystal axes is 25°≦λ≦85°.
- According to the sensor element of this application example, compared with the case where an X-cut plate with λ=0° is used as the piezoelectric substrate of the sensor element, a site where a large strain is generated by a compressive force applied to the piezoelectric substrate extends to an outer part of the piezoelectric substrate and therefore an electric charge generation site area where more electric charge is generated by an increase in the strain is broadened. Thus, a sensor element with high detection capability can be provided.
- This application example is directed to the above application example, where the single crystal is a rock crystal.
- According to this application example, by using a rock crystal substrate as the piezoelectric substrate, a large amount of electric charge can be generated even with a very small strain and a sensor element with high detection capability can be provided. Moreover, a single crystal can be easily obtained and a piezoelectric substrate with excellent workability and quality stability can be formed. Thus, a sensor element capable of stable detection can be provided.
- This application example is directed to a force detecting device including the above sensor element, and an arithmetic unit which detects an amount of electric charge induced in the first electrode or the second electrode and calculates a force applied to the sensor element.
- According to the force detecting device of this application example, a triaxial force detecting device can be provided with a simple configuration. Also, by using plural such triaxial force detecting devices, for example, a six-axis force detecting device including torque measuring can be easily provided.
- This application example is directed to a robot including the above sensor element, and an arithmetic unit which detects an amount of electric charge induced in the first electrode or the second electrode and calculates a force applied to the sensor element.
- According to the robot of this application example, a contact with an obstacle and a contacting force to an object during a predetermined operation of a robot arm or robot hand that make differential movements are securely detected by a force detecting device and data is fed back to a robot control device. Thus, a robot capable of performing safe and fine work can be provided.
- The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
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FIGS. 1A to 1C show a sensor element according to a first embodiment.FIG. 1A is a sectional view.FIG. 1B is an exploded perspective view.FIG. 1C is a view from the direction of an arrow A inFIG. 1B . -
FIG. 2 is a schematic view showing a method for forming a rock crystal substrate according to the first embodiment in relation to crystal axes X, Y, and Z. -
FIGS. 3A to 3C show a sensor element according to a second embodiment.FIG. 3A is a sectional view.FIG. 3B is an exploded perspective view.FIG. 3C is a view from the direction of an arrow B inFIG. 2B . -
FIG. 4 is a schematic view showing a method for forming a rock crystal substrate according to the second embodiment in relation to crystal axes X, Y, and Z. -
FIGS. 5A and 5B are plan views showing other forms of the rock crystal substrate according to the second embodiment. -
FIG. 6 is a sectional view showing a sensor device according to a third embodiment. -
FIGS. 7A to 7C show sensor devices as other forms of the third embodiment.FIG. 7A is a sectional view.FIGS. 7B and 7C are exploded perspective views. -
FIGS. 8A and 8B show a force detecting device according to a fourth embodiment.FIG. 8A is a sectional view.FIG. 8B is a conceptual view showing the arrangement of sensor devices. -
FIGS. 9A and 9B show another force detecting device according to the fourth embodiment.FIG. 9A is a plan view.FIG. 9B is a sectional view taken along C-C′ inFIG. 9A . -
FIG. 10 shows the configuration of a robot according to a fifth embodiment. -
FIGS. 11A and 11B are graphs showing examples of implementation.FIG. 11A shows an example of implementation of the sensor element according to the first embodiment.FIG. 11B shows an example of implementation of the sensor element according to the second embodiment. - Hereinafter, embodiments of the invention will be described.
-
FIGS. 1A to 1C show a sensor element according to a first embodiment.FIG. 1A is a sectional view.FIG. 1B is an exploded perspective view.FIG. 1C is a view from the direction of an arrow A inFIG. 1B . Asensor element 100 shown inFIGS. 1A to 1C includes arock crystal substrate 10 as a piezoelectric substrate, adetection electrode 20 as a first electrode, and a grounding electrode (hereinafter referred to as GND electrode) 30 as a second electrode. The material of the piezoelectric substrate is not limited to rock crystal as long as the material is a trigonal single crystal. A trigonal single crystal refers to a crystal which has crystal axes such that three symmetry axes with equal lengths intersect each other at an angle of 120°, with one vertical axis meeting the point of intersection. In addition to rock crystal, trigonal single crystals include langasite (La3Ga5SiO14), lithium niobate (LiNbO3) single crystal, lithium tantalate (LiTaO3) single crystal, gallium phosphate (GaPO4) single crystal, lithium borate (Li2B4O7) single crystal and the like. In this embodiment, a rock crystal which can generate a large amount of electric charge even with a very small strain and can easily provide a single crystal and also has excellent workability and quality stability is used. - In the
sensor element 100 shown inFIG. 1A , thedetection electrode 20 is arranged on one substrate surface 10 a of therock crystal substrate 10, and theGND electrode 30 is arranged on the other substrate surface 10 b. Therock crystal substrate 10 is held between thedetection electrode 20 and theGND electrode 30. That is, in terms of the illustrated coordinate axes α, β, γ, thedetection electrode 20, therock crystal substrate 10 and theGND electrode 30 are stacked in this order in the γ direction, thus forming thesensor element 100. If a force Fα in a shear direction along the illustrated α-axis direction is applied to thesensor element 100, therock crystal substrate 10 is deformed into a shape like a deformedrock crystal substrate 10′. With the strain due to this deformation, electric charge is generated in therock crystal substrate 10. - Here, in the case where the
rock crystal substrate 10 is made of a so-called Y-cut plate in which a plane intersecting the Y-axis as the mechanical axis of the crystal axes and including the X-axis as the electrical axis constitutes a main surface, if the deformation shown inFIG. 1A , that is, the strain that causes the deformation into therock crystal substrate 10′ is generated, positive (+) electric charge is generated inside therock crystal substrate 10 on the side of the one substrate surface 10 a of therock crystal substrate 10 where thedetection electrode 20 is arranged, and negative (−) electric charge is generated inside therock crystal substrate 10 on the side of the other substrate surface 10 b where theGND electrode 30 is arranged. The − electric charge on the side of the other substrate surface 10 b is discharged to the ground (GND), not shown, by theGND electrode 30. The + electric charge on the side of the one substrate surface 10 a is sent as a detection value to an arithmetic unit, not shown, by thedetection electrode 20. Based on the resulting amount of electric charge, the force Fα in the α direction is calculated. - In the
rock crystal substrate 10 made of a rock crystal that is a trigonal single crystal as a piezoelectric body, electric charge is generated as described above by an internal strain. The amount of this electric charge increases and decreases depending on the angle of the substrate surfaces 10 a, 10 b of therock crystal substrate 10 to the crystal axes X, Y, Z. A larger amount of electric charge can be obtained particularly depending on the following forming conditions of the substrate surfaces 10 a, 10 b. -
FIG. 1C shows therock crystal substrate 10, as viewed from the direction of the arrow A shown inFIG. 1B along the α-axis. As shown inFIG. 1C , if the substrate surfaces 10 a, 10 b of therock crystal substrate 10 are defined in terms of the crystal axes X, Y, Z, therock crystal substrate 10 is sliced out with an angle θ formed by the one substrate surface 10 a of therock crystal substrate 10 and a plane defined by the Z-axis and X-axis. -
FIG. 2 schematically shows the method for forming therock crystal substrate 10 in relation to the crystal axes X (electrical axis), Y (mechanical axis), Z (optical axis). As shown inFIG. 2 , therock crystal substrate 10 is formed in such a way that an angle formed by a surface 1 a including the X-axis and Z-axis and orthogonal to the Y-axis, of arock crystal body 1 sliced out along the crystal axes X, Y, Z, and the substrate surfaces 10 a, 10 b, within a plane defined by the Y-axis and Z-axis, becomes the angle θ. The angle θ may be preferably formed within a range of 0°<θ<20°. By thus forming therock crystal substrate 10, the amount of electric charge generated by the force Fα can be increased and a sensor element with high detection capability can be provided. -
FIGS. 3A to 3C show a sensor element according to a second embodiment.FIG. 3A is a sectional view.FIG. 3B is an exploded perspective view.FIG. 3C is a view from the direction of an arrow B inFIG. 3B . Asensor element 200 according to the second embodiment is different in the form of therock crystal substrate 10 from thesensor element 100 according to the first embodiment, and the other parts of the configuration are the same as the first embodiment. Therefore, the same parts of the configuration are denoted by the same reference numerals and will not be described further in detail. As shown inFIGS. 3A to 3C , thesensor element 200 according to the second embodiment is thesensor element 200 that detects a force Fγ in a direction in which arock crystal substrate 40 is compressed, that is, in a γ direction. Thesensor element 200 has a configuration in which adetection electrode 20 as a first electrode, therock crystal substrate 40 as a piezoelectric substrate, and aGND electrode 30 as a second electrode are stacked in the γ direction. As in thesensor element 100 according to the first embodiment, the material of the piezoelectric substrate is not limited to rock crystal as long as the material is a trigonal single crystal. However, also in this embodiment, an example in which a rock crystal is used as a piezoelectric material is described. - If a compressive force Fγ in the γ direction is applied to the
sensor element 200, as shown inFIG. 3A , therock crystal substrate 40 is compressed and deformed into a shape like arock crystal substrate 40′. With the strain due to this deformation, electric charge is generated in therock crystal substrate 40. Here, therock crystal substrate 40 is made of a so-called X-cut plate in which a plane intersecting the X-axis as the electrical axis of the crystal axes and including the Y-axis as the mechanical axis and the Z-axis as the optical axis constitutes a main surface. If the deformation shown inFIG. 3A , that is, the strain is generated, positive (+) electric charge is generated inside therock crystal substrate 40 on the side of one substrate surface 40 a of therock crystal substrate 40 where thedetection electrode 20 is arranged, and negative (−) electric charge is generated inside therock crystal substrate 40 on the side of the other substrate surface 40 b where theGND electrode 30 is arranged. The − electric charge on the side of the other substrate surface 40 b is discharged to the ground (GND), not shown, by theGND electrode 30. The + electric charge on the side of the one substrate surface 40 a is sent as a detection value to an arithmetic unit, not shown, by thedetection electrode 20. Based on the resulting amount of electric charge, the force Fγ in the γ direction is calculated. - In the
rock crystal substrate 40 made of a rock crystal that is a trigonal single crystal as a piezoelectric body, electric charge is generated as described above by an internal strain. The amount of this electric charge increases and decreases depending on the angle formed by planes 40 c, 40 d forming a part of an outer surface intersecting the substrate surfaces 40 a, 40 b of therock crystal substrate 40 and the surface defined by the X-axis and Z-axis. A larger amount of electric charge can be obtained particularly depending on the following forming conditions of the planes 40 c, 40 d. -
FIG. 3C shows a view from the direction of the arrow B shown inFIG. 3B . As shown inFIG. 3C , the outer surface forming the outer shape of therock crystal substrate 40 includes at least one plane. In this embodiment, the outer surface includes the planes 40 c, 40 d. Therock crystal substrate 40 is sliced out in such a way that the plane 40 d has an angle λ relative to a plane defined by the X-axis and Y-axis of the crystal axes. In this embodiment, therock crystal substrate 40 is rectangular and the plane 40 c and the plane 40 d of the outer surface are substantially parallel to each other. Therefore, therock crystal substrate 40 is sliced out in such a way that the plane 40 c, too, has an angle λ relative to the plane defined by the X-axis and Y-axis of the crystal axes. -
FIG. 4 schematically shows the method for forming therock crystal substrate 40 in relation to the crystal axes X, Y, Z. As shown inFIG. 4 , therock crystal substrate 40 is formed in such a way that an angle formed by a surface 2 a defined by the X-axis and Z-axis of arock crystal body 2 sliced out along the crystal axes X, Y, Z and the plane 40 d of the outer surface becomes the angle λ. Since the plane 40 c is substantially parallel to the plane 40 d, therock crystal substrate 40 is formed in such a way that an angle formed by the surface 2 a and the plane 40 c becomes the angle λ, too. The angle λ may be preferably formed within a range of 25°≦λ≦85°. By thus forming therock crystal substrate 40, the amount of electric charge generated by the force Fγ can be increased and a sensor element with high detection capability can be provided. -
FIGS. 5A and 5B are views showing other forms of therock crystal substrate 40. In therock crystal substrate 40 according to the second embodiment, as described above, as the plane 40 c or the plane 40 d of the outer surface intersects the surface 2 a (seeFIG. 4 ) defined by the X-axis and Z-axis, at the angle λ, a large amount of electric charge is generated. Therefore, the outer surface except the planes 40 c, 40 d is not limited to a plane. That is, as in arock crystal substrate 41 shown inFIG. 5A , parts other than a plane 41 c or a plane 41 d intersecting the surface 2 a (seeFIG. 4 ) defined by the X-axis and Z-axis, at the angle λ, may be round surfaces 41 a, 41 b. Also, as in a rock crystal substrate 42 shown inFIG. 5B , one plane 42 b may intersect the surface 2 a (seeFIG. 4 ) defined by the X-axis and Z-axis, at the angle λ, and the other parts of the surface may be a round surface 42 a or the like. -
FIG. 6 is a sectional view showing a sensor device according to a third embodiment. As shown inFIG. 6 , in asensor device 1000, thesensor element 100 having therock crystal substrate 10 or thesensor element 200 having therock crystal substrate 40 is housed in a cylindrical container 400 and is pressed and fixed bybases detection electrode 20 and theGND electrode 30 are electrically connected to anarithmetic unit 500. Thearithmetic unit 500 includes a QV amplifier, not shown, which converts the electric charge obtained by thedetection electrode 20, and also includes GND (ground) connected with theGND electrode 30. By employing such a configuration, thesensor device 1000 can easily detect a force applied between the base 301 and thebase 302. -
FIGS. 7A to 7C show sensor devices FIG. 7A is a sectional view.FIG. 7B is an exploded perspective view of thesensor device 1100.FIG. 7C is an exploded perspective view of thesensor device 1200. Thesensor devices FIGS. 7A to 7C have a configuration in which therock crystal substrate 10 or therock crystal substrate 40 as a piezoelectric substrate is arranged on both sides of thedetection electrode 20, compared with theabove sensor device 1000. That is, twosensor elements 100 or twosensor elements 200 are stacked, sharing thedetection electrode 20. As shown inFIG. 7A , in thesensor device 1100, asensor element 101 and asensor element 102 are arranged so as to share thedetection electrode 20, and in thesensor device 1200, asensor element 201 and asensor element 202 are arranged so as to share thedetection electrode 20. - The two
sensor elements sensor elements cylindrical container 410 and pressed and fixed by thebases detection electrode 20 and theGND electrode 30 are electrically connected to anarithmetic unit 510. Thearithmetic unit 510 includes a QV amplifier, not shown, which converts the electric charge obtained by thedetection electrode 20, and also includes GND (ground) connected with theGND electrode 30. -
FIG. 7B shows the arrangement of thesensor elements sensor device 1100. As shown inFIG. 7B , thesensor element 101 and thesensor element 102 are stacked along an illustrated stacking direction N, with the γ directions of the sensor elements aligned, as in thesensor element 100 according to the first embodiment. Here, thesensor element 101 and thesensor element 102 are arranged so that the α directions and γ directions of the sensor elements become opposite to each other so that electric charge of the same polarity is generated on the surface 10 a that contacts thedetection electrode 20, of therock crystal substrate 10 on the upper side in the illustrated N direction, and on the surface 10 b of therock crystal substrate 10 on the lower side in the illustrated N direction, when a force along an illustrated L direction is detected in thesensor device 1100. -
FIG. 7C shows the arrangement of thesensor elements sensor device 1200. As shown inFIG. 7C , thesensor element 201 and thesensor element 202 are arranged with the sides of each sensor element reversed to each other, that is, so that the one substrate surface 40 a of therock crystal substrate 40 contacts thedetection electrode 20. Thus, when a force along the N direction, that is, a force in the compressing direction is applied, electric charge of the same polarity can be generated on the one substrate surface 40 a of the tworock crystal substrates 40 contacting thedetection electrode 20. - By employing such a configuration, electric charge can be generated in the two
rock crystal substrates 10 orrock crystal substrates 40 by a force applied between the base 301 and thebase 302, and about twice the electric charge in thesensor device 1000 can be obtained. Therefore, thesensor devices -
FIGS. 8A and 8B show a force detecting device according to a fourth embodiment.FIG. 8A is a sectional view.FIG. 8B is a conceptual view showing the arrangement of sensor devices. InFIG. 8A , a direction in which electrodes and rock crystal substrates are stacked (upward direction inFIG. 8A ) is defined as a V(+) direction. A rightward direction inFIG. 8A , orthogonal to the V direction is an Hx(+) direction. A direction heading towardFIG. 8A from the viewer is an Hy(+) direction. In aforce detecting device 2000 shown inFIG. 8A , electrodes and rock crystal substrates are alternately stacked within a cylindrical container 420 between a base 311 and abase 312 and are pressed and fixed by the base 311 and thebase 312. - The electrodes and the rock crystal substrates housed in the cylindrical container 420 are stacked as follows. From the side of the base 311, a
sensor device 1101 in whichsensor elements sensor device 1100 according to the another form of the third embodiment, followed by asensor device 1102 in whichsensor elements sensor device 1100, and then asensor device 1200 in whichsensor elements sensor devices GND electrodes 30 except the GND electrode contacting thebases 311, 312 are shared by thesensor devices - As shown in
FIG. 8B , the arrangement of thesensor device 1102 is in a direction that results from rotating thesensor device 1101 by an angle of 90° about the V-axis. That is, the L-axis of thesensor device 1101 which detects a force along the L-axis is aligned with the Hx-axis, and thesensor device 1102 is arranged by rotating the L-axis by an angle of 90° about the V-axis and aligning the L-axis with the Hy-axis. Thus, forces along the Hx-axis and Hy-axis can be detected. Moreover, thesensor device 1200 which detects a force in the N-axis direction is arranged by aligning the N-axis with the V-axis. Thus, a force along the V-axis can be detected. In this manner, theforce detecting device 2000 incorporating thesensor devices - If a force is applied to the
bases 311, 312 of theforce detecting device 2000 thus configured, based on the electric charge generated in thesensor device arithmetic unit 610 based on the electric charge of thesensor device 1101, by an Hy directionarithmetic unit 620 based on the electric charge of thesensor device 1102, and by a V direction arithmetic unit 630 based on the electric charge of thesensor device 1200, are outputted to a control device, not shown, with the Hx, Hy and V directionarithmetic units arithmetic device 600 as an arithmetic unit. The electric charge excited in theGND electrode 30 is grounded and discharged byGND 640 provided in thearithmetic device 600. - As described above, the
force detecting device 2000 according to this embodiment can be a small-sized force detecting device by having electrodes and rock crystal substrates as piezoelectric substrates stacked in one direction. Also, the force detecting device of this embodiment can be formed by stacking electrodes and rock crystal substrates of simple shapes and therefore can be a low-cost force detecting device. -
FIGS. 9A and 9B schematically show a six-axisforce detecting device 3000 which uses theforce detecting device 2000 according to the above embodiment and is capable of torque detection.FIG. 9A is a plan view.FIG. 9B is a sectional view taken along C-C′ shown inFIG. 9A . As shown inFIGS. 9A and 9B , the six-axisforce detecting device 3000 has a configuration in which fourforce detecting devices 2000 are fixed by bases 321, 322. By employing this six-axisforce detecting device 3000, it is possible to find the torque about each of the Hx-axis, Hy-axis and V-axis based on the distance between the fourforce detecting devices 2000 that are arranged and the force obtained by eachforce detecting device 2000. -
FIG. 10 is an external view showing the configuration of arobot 4000 using theforce detecting device 2000 according to the third embodiment or the six-axisforce detecting device 3000. Therobot 4000 includes abody portion 4100, anarm portion 4200, arobot hand portion 4300 and the like. Thebody portion 4100 is fixed, for example, on a floor, wall, ceiling, movable trolley or the like. Thearm portion 4200 is provided movably in relation to thebody portion 4100. An actuator, not shown, which generates a motive force to rotate thearm portion 4200, a control unit which controls the actuator, and the like are arranged inside thebody portion 4100. - The
arm portion 4200 includes a first frame 4210, asecond frame 4220, athird frame 4230, afourth frame 4240 and afifth frame 4250. The first frame 4210 is connected to thebody portion 4100 in a rotatable or bendable manner via a rotation-bending axis. Thesecond frame 4220 is connected to the first frame 4210 and thethird frame 4230 via a rotation-bending axis. Thethird frame 4230 is connected to thesecond frame 4220 and thefourth frame 4240 via a rotation-bending axis. Thefourth frame 4240 is connected to thethird frame 4230 and thefifth frame 4250 via a rotation-bending axis. Thefifth frame 4250 is connected to thefourth frame 4240 via a rotation-bending axis. Under the control of the control unit, thearm portion 4200 operates as each of the frames 4210 to 4250 rotates or bends in a complex manner about each rotation-bending axis. - The
robot hand portion 4300 is attached on the side of thefifth frame 4250 of thearm portion 4200 that is opposite to the connecting part with thefourth frame 4240. Therobot hand portion 4300 includes a robot hand 4310 which can grip an object, and a robot hand connecting portion 4320 in which a motor to rotate the robot hand 4310 is arranged. Therobot hand portion 4300 is connected to thefifth frame 4250 by the robot hand connecting portion 4320. - In the robot hand connecting portion 4320, the
force detecting device 2000 according to the third embodiment or the six-axisforce detecting device 3000 is arranged in addition to the motor. Thus, when therobot hand portion 4300 is moved to a predetermined operating position under the control of the control unit, contact with an obstacle or contact with an object in response to an operation command to exceed a predetermined position, or the like, can be detected as a force by theforce detecting device 2000 or the six-axisforce detecting device 3000. This force can be fed back to the control unit of therobot 4000 so that an evasive action can be executed. - Using such a
robot 4000, a robot that can easily carry out an obstacle avoiding operation, an object damage avoiding operation and the like, which cannot be realized by traditional position control, and that can perform safe and fine work, can be provided. The technique is not limited to this embodiment and can also be applied to, for example, a two-arm robot. -
FIGS. 11A and 11B are graphs showing the amount of electric charge generated when a force is applied to thesensor element 100 according to the first embodiment and thesensor element 200 according to the second embodiment. The result of calculating the amount of electric charge in relation to the angle θ in the case of thesensor element 100 is shown inFIG. 11A . The result of calculating the amount of electric charge in relation to the angle λ in the case of thesensor element 200 is shown inFIG. 11B . The piezoelectric substrate is made of a rock crystal with a plane size of 5 mm by 5 mm and a thickness of 200 μm. Fα=500N and Fγ=500N are applied in the illustrated directions. - As shown in
FIG. 11A , in the case where thesensor element 100 according to the first embodiment is used, compared with a general Y-cut plate with θ=0°, an amount of electric charge exceeding the amount of electric charge in the case of θ=0° can be obtained if θ is increased within a range of 0°<θ<20°. - As shown in
FIG. 11B , in the case where thesensor element 200 according to the second embodiment is used, compared with a general X-cut plate with λ=0°, an amount of electric charge exceeding the amount of electric charge in the case of λ=0° can be obtained if λ is within a range of 25°≦λ≦85°.
Claims (5)
1. A robot comprising:
a piezoelectric substrate including a trigonal single crystal having crystal axes;
a first electrode on a first surface of the piezoelectric substrate;
a second electrode on a second surface, the first and second surfaces being on opposite sides of the piezoelectric substrate;
an arithmetic unit which detects an amount of electric charge induced in the first or second electrode and calculates a force applied to the piezoelectric substrate;
a rotatable arm portion; and
a hand portion supported on the arm portion via the piezoelectric substrate, the hand portion being adapted to grip an object;
wherein the first surface of the piezoelectric substrate includes an electrical axis of the crystal axes,
an angle θ between the first surface and a plane including the electrical axis and an optical axis of the crystal axes is 0°<θ<20°, and
a material for the piezoelectric electric substrate is selected from the group consisting of langasite (La3Ga5SiO14), lithium niobate (LiNbO3) single crystal, lithium tantalite (LiTaO3) single crystal, gallium phosphate (GaPO4) single crystal, and lithium borate (Li2B4O7) single crystal.
2. The robot according to claim 1 , comprising four of the sensor units.
3. The robot according to claim 1 , wherein the first surface of the piezoelectric substrate includes the electrical axis, a mechanical axis, and an optical axis of the crystal axes,
a portion of an outer side surface that is different from the first and second surfaces of the piezoelectric substrate includes a plane, and
an angle λ between the plane of the outer side surface and a plane including an electrical axis and the optical axis of the crystal axes is 25°≦λ≦85°.
4. A robot comprising:
a piezoelectric substrate including a trigonal single crystal having crystal axes;
a first electrode on a first surface of the piezoelectric substrate; and a second electrode on a second surface, the first and second surfaces being on opposite sides of the piezoelectric substrate;
an arithmetic unit which detects an amount of electric charge induced in the first electrode or the second electrode and calculates a force applied to the piezoelectric substrate;
a rotatable arm portion; and
a hand portion supported on the arm portion via the sensor element, the hand portion being adapted to grip an object;
wherein the first surface of the piezoelectric substrate includes a mechanical axis and an optical axis of the crystal axes,
an outer side surface being different from the first and second surfaces of the piezoelectric substrate includes a plane,
an angle λ between the plane of the outer surface and a plane including an electrical axis and the optical axis of the crystal axes is 25°≦λ≦85°, and
a material for the piezoelectric electric substrate is selected from the group consisting of langasite (La3Ga5SiO14), lithium niobate (LiNbO3) single crystal, lithium tantalite (LiTaO3) single crystal, gallium phosphate (GaPO4) single crystal, and lithium borate (Li2B4O7) single crystal.
5. The robot according to claim 4 , comprising four of the sensor units.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US14/722,248 US20150276513A1 (en) | 2011-11-08 | 2015-05-27 | Sensor element, force detecting device, robot and sensor device |
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JP2011-244208 | 2011-11-08 | ||
JP2011244208A JP5811785B2 (en) | 2011-11-08 | 2011-11-08 | Sensor element, force detection device and robot |
US13/669,879 US9102067B2 (en) | 2011-11-08 | 2012-11-06 | Sensor element, force detecting device, robot and sensor device |
US14/722,248 US20150276513A1 (en) | 2011-11-08 | 2015-05-27 | Sensor element, force detecting device, robot and sensor device |
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US13/669,879 Continuation US9102067B2 (en) | 2011-11-08 | 2012-11-06 | Sensor element, force detecting device, robot and sensor device |
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US13/669,879 Active 2033-06-06 US9102067B2 (en) | 2011-11-08 | 2012-11-06 | Sensor element, force detecting device, robot and sensor device |
US14/722,248 Abandoned US20150276513A1 (en) | 2011-11-08 | 2015-05-27 | Sensor element, force detecting device, robot and sensor device |
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CN106363260A (en) * | 2016-11-22 | 2017-02-01 | 天津大学 | Mechanical arm for electrolytic machining of corrosion defects in pipe |
US20210190609A1 (en) * | 2018-01-24 | 2021-06-24 | Avl List Gmbh | Measuring system and method for determining a force and/or a torque on a torque-transmitting shaft |
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JP5811785B2 (en) * | 2011-11-08 | 2015-11-11 | セイコーエプソン株式会社 | Sensor element, force detection device and robot |
JP2015087289A (en) * | 2013-10-31 | 2015-05-07 | セイコーエプソン株式会社 | Sensor element, force detection device, robot, electronic component conveyance device, electronic component inspection device, and component processing device |
CN104614118B (en) * | 2013-11-05 | 2019-01-11 | 精工爱普生株式会社 | Force checking device, robot and electronic component handling apparatus |
US10061213B2 (en) * | 2014-09-02 | 2018-08-28 | Asml Netherlands B.V. | Sensor, object positioning system, lithographic apparatus and device manufacturing method |
CN106142133B (en) * | 2016-06-20 | 2018-12-11 | 昆山国显光电有限公司 | Mechanical arm and its electrostatic detection methods |
JP2018189385A (en) * | 2017-04-28 | 2018-11-29 | セイコーエプソン株式会社 | Force detection device and robot |
CN109974764A (en) * | 2017-12-27 | 2019-07-05 | 天津明源机械设备有限公司 | A kind of automatic appearance test device |
JP7192292B2 (en) * | 2018-07-30 | 2022-12-20 | セイコーエプソン株式会社 | Robot and robot anomaly detection method |
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Also Published As
Publication number | Publication date |
---|---|
CN103091004B (en) | 2016-10-26 |
US9102067B2 (en) | 2015-08-11 |
JP2013101018A (en) | 2013-05-23 |
JP5811785B2 (en) | 2015-11-11 |
CN103091004A (en) | 2013-05-08 |
US20130112011A1 (en) | 2013-05-09 |
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