CN113167670B - Elastic body and force sensor using same - Google Patents
Elastic body and force sensor using same Download PDFInfo
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- CN113167670B CN113167670B CN201980078288.5A CN201980078288A CN113167670B CN 113167670 B CN113167670 B CN 113167670B CN 201980078288 A CN201980078288 A CN 201980078288A CN 113167670 B CN113167670 B CN 113167670B
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- 239000002184 metal Substances 0.000 claims abstract description 23
- 229920001971 elastomer Polymers 0.000 claims description 8
- 239000000806 elastomer Substances 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 description 28
- 238000005452 bending Methods 0.000 description 15
- 238000012545 processing Methods 0.000 description 7
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 239000000470 constituent Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000009751 slip forming Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
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Classifications
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- 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
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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
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
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- 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
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Robotics (AREA)
- Mechanical Engineering (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
- Measurement Of Force In General (AREA)
- Manipulator (AREA)
Abstract
The elastic body is provided with a first structure (16-1), a plurality of second structures (16-2), and a plurality of third structures (16-3). A plurality of first elastic parts (16-4) which can deform in the six-axis direction are connected to the first structural body (16-1). Each of the second structures (16-2) has a second elastic section (16-5) that is deformable in the six-axis direction and a relay section (16-6) that is connected to the second elastic section. A plurality of third structures (16-3) are provided between the relay sections of the second structures and the first elastic sections. The first structure, the second structure, the third structure, the relay section, the first elastic section, and the second elastic section are formed of a single metal plate, and the second structure, the third structure, the relay section, the first elastic section, and the second elastic section are bent metal plates.
Description
Technical Field
Embodiments of the present invention relate to an elastic body used for, for example, a robot arm or the like, and a force sensor using the elastic body.
Background
The force sensor is used for, for example, a robot arm or the like, and detects forces (Fx, fy, fz) and moments (Mx, my, mz) about three orthogonal axes (x, y, z) (see, for example, patent document 1).
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open publication No. 2018-48915
Disclosure of Invention
The force sensor includes an elastic body deformable in six-axis directions, for example, three-axis directions and directions around the three axes, and a plurality of strain sensors are provided on the elastic body. Each strain sensor is provided with a plurality of strain gauges on a strain body. In addition, the force sensor is provided with a stopper to protect the elastic body and the strain body from an external force.
When the elastic body and the strain body (hereinafter, both of them are collectively referred to as a sensor body) have high rigidity and the displacement amount in the six-axis direction is extremely small, high processing accuracy is required for the structure of the stopper, and the stopper is difficult to realize.
In addition, when the rigidity of the sensor body greatly differs in each axial direction, the design of the stopper becomes complicated, and the realization of the stopper becomes difficult.
On the other hand, when the sensor body is designed without providing the stopper, it is difficult to increase the displacement of the elastic body and the strain body, and therefore, a large sensor output cannot be obtained, and the sensor is weak in noise and the like, and has low measurement accuracy.
Embodiments of the present invention provide an elastic body capable of obtaining a sufficient sensor output and improving measurement accuracy, and a force sensor using the elastic body.
The present embodiment provides an elastic body including: a first structure body including a plurality of first elastic portions deformable in a six-axis direction; a plurality of second structures having a second elastic portion deformable in the six-axis direction and a relay portion connected to the second elastic portion; and a plurality of third structures provided between each of the relay portions of the second structure and each of the first elastic portions, wherein the first structures, the second structures, the third structures, the relay portions, the first elastic portions, and the second elastic portions are formed of a single metal plate, and the second structures, the third structures, the relay portions, the first elastic portions, and the second elastic portions are formed by bending the metal plate.
The present embodiment provides a force sensor including: a first structural body to which a plurality of first elastic portions deformable in a six-axis direction are connected; a plurality of second structures each having a second elastic portion deformable in the six-axis direction and a relay portion connected to the second elastic portion; a plurality of third structures provided between the relay portion and each of the first elastic portions of the second structures; and a plurality of strain sensors provided between the relay sections of the first structure and the second structure, wherein the first structure, the second structure, the third structure, the relay sections, the first elastic sections, and the second elastic sections are formed of a single metal plate, and the second structure, the third structure, the relay sections, the first elastic sections, and the second elastic sections are formed by bending the metal plate.
Drawings
Fig. 1 is a perspective view showing a force sensor according to the present embodiment.
Fig. 2 is an exploded perspective view of the force sensor shown in fig. 1.
Fig. 3 is a perspective view showing a state in which a part of the force sensor shown in fig. 2 is assembled.
Fig. 4 is a perspective view showing a state in which a part of the force sensor shown in fig. 2 is further assembled.
Fig. 5 is a perspective view showing a part of the force sensor shown in fig. 2 in a further exploded manner.
Fig. 6 is a plan view showing the elastic body of the present embodiment taken out.
Fig. 7 is a perspective view showing the elastic body according to the present embodiment with a part thereof removed.
Fig. 8A is a diagram illustrating an example of deformation of the elastic body according to the present embodiment, and is a side sectional view partially taken out.
Fig. 8B is a perspective view showing an example of deformation of the strain body accompanying the deformation shown in fig. 8A.
Fig. 8C is a diagram showing an example of deformation of an elastic body as a reference example, and is a side sectional view partially taken out and shown.
Fig. 8D is a perspective view showing an example of deformation of the strain body accompanying the deformation shown in fig. 8C.
Fig. 9 is a plan view showing an example of the strain sensor.
Fig. 10 is a circuit diagram showing an example of the bridge circuit.
Fig. 11 is a view showing a modification of the elastic body according to the present embodiment, and is a perspective view partially taken out.
Detailed Description
Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same reference numerals are given to the same parts.
The structure of the force sensor 10 according to the present embodiment will be described with reference to fig. 1 to 6.
The force sensor 10 is used for, for example, a robot arm or the like, and detects a force (Fx, fy, fz) in the X, Y, Z axial direction and a torque (moment: mx, my, mz) around X, Y, Z axis.
As shown in fig. 1 and 2, the force sensor 10 includes a cylindrical body 11 and a cylindrical cover 12 covering the body 11. An attachment plate 13 as a movable body that is movable relative to the main body 11 is provided inside the cover 12, and the attachment plate 13 is fixed to the cover 12 by a plurality of screws 14. The cover 12 and the mounting plate 13 are provided to be movable with respect to the main body 11.
The body 11 is fixed to, for example, a body of a robot arm not shown. The mounting plate 13 is fixed to, for example, a hand portion of the robot arm.
An annular seal member 15 is provided between the body 11 and the cover 12. The sealing member 15 is formed of an elastic material, such as rubber or a foamed member, seals a gap between the main body 11 and the cover 12, and the cover 12 is movable with respect to the main body 11.
As shown in fig. 3, an elastic body 16 is provided between the main body 11 and the mounting plate 13. As described later, the elastic body 16 is formed by, for example, bending a single metal sheet, and includes: one first structure body 16-1, a plurality of second structure bodies 16-2, a plurality of third structure bodies 16-3 disposed between the first structure body 16-1 and the second structure body 16-2, and the like. The plurality of second structures 16-2 are arranged at equal intervals around the first structure 16-1.
In the present embodiment, the elastic body 16 includes, for example, three second structures 16-2. However, the number of the second structures 16-2 is not limited to 3, and may be 3 or more. In addition, when the present embodiment is applied to, for example, a torque sensor other than the force sensor, the number of the second structures 16-2 may be two.
6 first elastic portions 16-4 are provided around the first structural body 16-1. The first elastic portion 16-4 is continuous with the third structural body 16-3 and is disposed around the first structural body 16-1.
Each of the second structures 16-2 includes two second elastic portions 16-5 each having a substantially U shape and a relay portion 16-6 on a straight line connecting the two second elastic portions 16-5 between the two second elastic portions 16-5.
The third structure 16-3 has one end connected to the first elastic portion 16-4 and the other end connected to the relay portion 16-6. Two third structures 16-3 provided between the first structure 16-1 and one second structure 16-2 are arranged in parallel with each other.
The second structure 16-2 is fixed to the main body 11 by a plurality of screws 17, and as shown in fig. 2 and 4, the first structure 16-1 is fixed to the mounting plate 13 by a plurality of screws 18.
As shown in fig. 2 and 3, the strain sensor 19 is provided between the first structure body 16-1 and the relay portion 16-6. Specifically, one end of the strain sensor 19 is fixed to the first structural body 16-1 between the two first elastic parts 16-4 by screws 21 inserted into the fixed plate 20 and the back surfaces of the first elastic parts 16-4, and the other end of the strain sensor 19 is fixed to the center of the relay part 16-6 by screws 23 inserted into the fixed plate 22 and the back surfaces of the relay part 16-6. As will be described later, the strain sensor 19 has a plurality of strain gauges disposed on the surface of a metal strain body.
When the mounting plate 13 and the cover 12 are moved relative to the main body 11 by an external force, the third structural body 16-3, the first elastic portion 16-4, the second elastic portion 16-5, and the relay portion 16-6 are deformed. In response to this, the strain body of the strain sensor 19 deforms, and an electrical signal is output from the strain gauge.
As will be described later, the strain gauges of the strain sensors 19 constitute a bridge circuit, and the force (Fx, fy, and Fz) in the X, Y, Z axis direction and the torque (moment: mx, my, and Mz) around the X, Y, Z axis are detected by the bridge circuit.
As shown in fig. 2, a plurality of stoppers 30 for protecting the elastic body 16 from an external force are provided on the main body 11. Each stopper 30 is composed of a cylindrical stopper member 31, a screw 32 as a fixing member, and a plurality of openings 13a provided in the mounting plate 13.
This embodiment shows a case where three stoppers 30 are provided. However, the number of the stoppers 30 is not limited to 3, and may be 3 or more. The three stoppers 30 are respectively disposed between the three second structural bodies 16-2.
By disposing the stopper 30 between the second structures 16-2, the increase in the diameter and the outer shape of the elastic body 16 and the force sensor as a whole can be suppressed.
On the surface of the main body 11, 3 protrusions 11a are provided at positions corresponding to each other of the three second structures 16-2.
As shown in fig. 4, the stopper member 31 is fixed to the projection 11a of the body 11 with a screw 32 in a state of being inserted into the opening 13a of the attachment plate 13. As will be described later, the outer diameter of the stopper member 31 is set to be slightly smaller than the inner diameter of the opening 13 a. When the attachment plate 13 moves relative to the main body 11 and the outer surface of the stopper member 31 abuts against the inner surface of the opening 13a, the movement of the attachment plate 13 is stopped, and the elastic body 16 and the strain body of the strain sensor 19 are prevented from being broken.
As shown in fig. 5, a printed circuit board 41, a plurality of flexible printed circuit boards 42, a back cover 43, a lead assembly 44, and a hollow tube 45 are provided on the back surface of the main body 11. The printed board 41 includes a processing circuit, not shown, for supplying power to the bridge circuit and processing an output signal of the bridge circuit.
As shown in fig. 2, one end portions of the plurality of flexible printed boards 42 are disposed on the upper surface side of the main body 11 and connected to the strain sensors 19. The other end portions of the plurality of flexible printed boards 42 are connected to a processing circuit or the like on the rear surface of the printed board 41. The plurality of flexible printed boards 42 supply power to the strain gauges or supply signals from the strain gauges to the processing circuit.
The lead assembly 44 is connected to the printed circuit board 41, and supplies power to the processing circuit or transmits a signal from the processing circuit. The back cover 43 is fixed to the main body 11 by a plurality of screws and covers the printed board 41.
An opening is provided in the center of the body 11, the cover 12, the mounting plate 13, the first structural body 16-1 of the elastic body 16, the printed circuit board 41, and the back cover 43 so as to communicate with each other, and a hollow tube 45 is provided in the opening.
As shown in fig. 2 and 3, one end of the hollow tube 45 penetrates the back cover 43, the printed circuit board 41, and the first structure 16-1, and protrudes from the surface of the first structure 16-1. An annular seal member 26 is provided at one end of the hollow tube 45 projecting from the surface of the first structural body 16-1. The sealing member 26 is made of, for example, rubber or a foamed material, and seals a gap between the opening of the mounting plate 13 and one end of the hollow tube 25. This prevents dust from entering the mounting plate 13 from the outside of the cover 12.
(Structure of elastomer)
Fig. 6 shows an elastic body 16 according to the present embodiment. As described above, the elastic body 16 is formed by bending a single metal sheet. The elastic body 16 includes: one first structure 16-1, three second structures 16-2, 6 third structures 16-3, a first elastic portion 16-4 provided to each third structure 16-3, two second elastic portions 16-5 provided to each second structure 16-2, a relay portion 16-6 provided between the two second elastic portions 16-5 and between the two third structures 16-3, and a beam portion 16-7 connecting the first structure 16-1 and the relay portion 16-6.
Fig. 6 a shows a state in which a part of the elastic body 16 is stretched. The first structure 16-1, the second structure 16-2, the third structure 16-3, the first elastic portion 16-4, the second elastic portion 16-5, the intermediate portion 16-6, and the beam portion 16-7 are formed by, for example, punching out from a single metal plate.
The relay section 16-6 is connected to the first structure 16-1 by the beam section 16-7. The second elastic portion 16-5 and the second structural body 16-2 are continuously formed on both sides of the intermediate portion 16-6, and the third structural body 16-3 and the first elastic portion 16-4 are also continuously formed.
The first elastic portion 16-4 is provided at one end portion (front end portion) in the longitudinal direction of the third structural body 16-3 in a direction (width direction) intersecting the longitudinal direction.
The second structure 16-2, the third structure 16-3, and the second elastic portion 16-5 have a width W, and the width W1 of the first elastic portion 16-4 is narrower than the width W. The width of the relay unit is approximately 2W.
The relationship among the thickness T (shown in FIG. 6) of the metal plate, the width W1 of the first elastic portion 16-4, the width W of the second elastic portion 16-5, the third structural body 16-3, etc., and the width 2W of the relay portion 16-6 can be changed as necessary.
The beam section 16-7 has a width equal to the thickness T of the metal plate, and the cross section of the beam section 16-7 is square. Therefore, the ease of deformation in each axial direction is equal. The beam portion 16-7 is used to connect the first structure 16-1 and the relay portion 16-6. However, the beam portion 16-7 may be omitted if, for example, a structure is provided that connects the first structural body 16-1 and the third structural body 16-3 or the first elastic portion 16-4.
As shown in a, the elastic body 16 shown in fig. 6 is formed by bending a plurality of bent portions B shown by broken lines of the punched metal plate. After bending each portion of the metal plate, the tip end portion of the first elastic portion 16-4 is fixed to the first structural body 16-1 by, for example, a screw. The method of fixing the first elastic portion 16-4 is not limited to this, and the distal end portion of the first elastic portion 16-4 may be welded to the first structural body 16-1 or bonded using an adhesive.
As will be described later, the first elastic portion 16-4 is bent with respect to the third structural body 16-3 and has a width W1 narrower than the width W of the third structural body 16-3 and the like. Therefore, the first elastic portion 16-4 has a bending or twisting rigidity that is lower than the rigidity of the second elastic portion 16-5.
The second elastic portion 16-5 is bent into a substantially U shape and has a lower bending or twisting rigidity than the second structural body 16-2.
The strain sensor 19 is provided between the first structural body 16-1 located between the two first elastic portions 16-4 and the central portion of the relay portion 16-6. The strain sensor 19 is located between the two third structures 16-3 and is arranged in parallel with the two third structures 16-3.
The thicknesses of the first elastic section 16-4, the second elastic section 16-5, the intermediate section 16-6, the first structural body 16-1, the second structural body 16-2, and the third structural body 16-3 are equal to the thickness T of the metal plate. The second elastic portion 16-5 is more flexible as the lengths L1 and L2 of the U-shaped portion become longer and as the thickness T of the metal plate becomes thinner, and the first elastic portion 16-4 and the relay portion 16-6 are also more flexible as the thickness T of the metal plate becomes thinner and/or as the width becomes narrower.
The thickness of the strain body 19a constituting the strain sensor 19 is smaller than the thicknesses of the first structure 16-1, the second structure 16-2, the third structure 16-3, the first elastic portion 16-4, the second elastic portion 16-5, and the relay portion 16-6, and the width of the strain body 19a is wider than the thickness T of the third structure 16-3, the first elastic portion 16-4, the second elastic portion 16-5, and the relay portion 16-6.
As will be described later, the strain body 19a has a rectangular shape with a small thickness and a flat shape with a large aspect ratio. Therefore, when the strain body 19a is a single body, the strain body 19a has a characteristic that the displacement is small with respect to the force in the Fx and Fy directions and the moment in the Mz direction, and the displacement is large with respect to the moment in the Mx and My directions and the force in the Fz direction, due to the difference in the cross-sectional second order moments.
On the other hand, when the displacement amount of the elastic body 16 is excessively small, high machining accuracy is required for the structure of the stopper 30. Further, when the displacement amounts of the force in the Fx and Fy directions and the moment in the Mz direction and the displacement amounts of the force in the Mx and My directions and the force in the Fz direction are large, the structure of the stopper 30 becomes complicated. Therefore, in order to configure a highly accurate force sensor with a stopper having a simple structure, it is necessary to make the difference in the displacement amount between the respective axes of the elastic body 16 small.
The elastic body 16 of the present embodiment has an increased displacement amount in a direction parallel to the X-Y plane (a plane including the X axis and the Y axis), and a large displacement amount can be realized as a sensor body even if the strain body 19a is slightly displaced.
The rigidity of the strain body 19a in the Z-axis direction is much smaller than the rigidity of the elastic body 16 in the Z-axis direction. Therefore, the rated load relating to the Z-axis bending of the force sensor cannot be applied to the strain body 19a alone. Therefore, the amount of displacement of the strain body 19a needs to be controlled.
Therefore, the function required of the elastic body 16 is (1) the amount of displacement is large in the X-Y plane. (2) The amount of displacement of the strain body 19a is controlled by the load in the Z-axis direction.
(function of the first elastic portion 16-4)
(1) Deformation of Mz system (Fx, fy, mz)
As shown in fig. 7, the first elastic portion 16-4 is bent at the bent portion 16-4a with respect to the third structural body 16-3, and the width W1 of the first elastic portion 16-4 is narrower than the width W of the third structural body 16-3 and the like. Therefore, the first elastic portion 16-4 has a rigidity equal to or lower than the rigidity of the second elastic portion 16-5, and is easily deformed in the direction of arrow C, D.
When a force in the Fx and Fy directions and a moment in the Mz direction are applied to the elastic body 16, the second structural body 16-2 moves relative to the first structural body 16-1, and the first elastic portion 16-4 connected to the third structural body 16-3 deforms so as to twist. Therefore, the displacement amount of the second structural body 16-2 relative to the first structural body 16-1 is increased. The strain body 19a is displaced in accordance with the thickness of the third structural body 16-3, the width of the strain body 19a, and the load, and the displacement amount of the strain body 19a is extremely small. That is, in the case of the present embodiment, the amount of displacement of the second structural body 16-2 with respect to the first structural body 16-1 can be increased as compared with the amount of displacement of the strain body 19a.
(2) Variants of Fz series (Mx, my, fz)
On the other hand, when a force in the Fz direction is applied to the elastic body 16 and when moments in the Mx and My directions are applied, the first elastic portion 16-4 to which the third structural body 16-3 is connected is deformed in the direction of arrow C, D shown in fig. 7. Therefore, the amount of displacement in the width direction of the third structural body 16-3 can be increased, and the amount of displacement in the thickness direction of the strain body 19a can be increased. Therefore, as will be described later, the third structure 16-3 can be deformed into a substantially S-shape, and the output voltage of the bridge circuit can be increased.
Fig. 8A shows an example of deformation of the elastic body 16 according to the present embodiment.
The rigidity of the first elastic section 16-4 connected to the first structural body 16-1 and the third structural body 16-3 is equal to or less than the rigidity of the second elastic section 16-5. Therefore, when a force in the Fz direction, for example, is applied to the elastic body 16, the first elastic portion 16-4 deforms, whereby the deformation of the second elastic portion 16-5 decreases and the amount of lift of the relay portion 16-6 decreases. Therefore, the third structural body 16-3 is deformed into a substantially S-shape, and the strain body 19a provided between the first structural body 16-1 and the relay portion 16-6 is also deformed into a substantially S-shape.
Fig. 8B schematically shows deformation of the strain body 19a accompanying deformation of the elastic body 16 shown in fig. 8A. As shown in the drawing, a plurality of strain gauges 51 to 54 are disposed on the surface of the strain body 19a.
When the strain body 19a is deformed into a substantially S-shape along with the deformation of the elastic body 16, the strain gauges 51 and 52 provided on the surface of the strain body 19a are extended, and the strain gauges 53 and 54 are compressed. Therefore, the difference between the resistance values of strain gauges 51 and 52 and the resistance values of strain gauges 53 and 54 becomes large, and the output voltage of the bridge circuit including strain gauges 51 to 54 can be increased. Therefore, the accuracy of the force sensor can be improved.
Fig. 8C shows deformation of the elastic body 60 as a comparative example. The elastic body 60 is obtained by removing the first elastic portion 16-4 from the elastic body 16 of the present embodiment. In the absence of the first elastic portion 16-4, when a force in the Fz direction, for example, is applied to the elastic body 60, the third structural body 16-3 bends due to bending or twisting deformation of the second elastic portion 16-5 having lower rigidity than the second structural body 16-2. Subsequently, the relay section 16-6 is raised. Therefore, the strain body 19a provided between the first structural body 16-1 and the relay portion 16-6 is also bent.
Fig. 8D shows deformation of the strain body 19a accompanying deformation of the elastic body 60 shown in fig. 8C. When the strain body 19a is bent in accordance with the bending of the elastic body 60, the strain gauges 51 and 52 and the strain gauges 53 and 54 provided on the surface of the strain body 19a are simultaneously extended. Therefore, the difference between the resistance values of the gauges 51 and 52 and the resistance values of the gauges 53 and 54 is small, and the output voltage of the bridge circuit formed by the gauges 51 to 54 is also small. Therefore, it is difficult to improve the accuracy of the force sensor.
(function of the second elastic part 16-5)
The second elastic portion 16-5 has lower bending or twisting rigidity than the second structural body 16-2. Therefore, even when a force in the Fx and Fy directions is applied to the elastic body 16 and a moment in the Mz direction is applied, the displacement amount of the second structural body 16-2 with respect to the first structural body 16-1 can be increased even if the strain body 19a provided between the first structural body 16-1 and the relay portion 16-6 is displaced by an amount controlled by the third structural body 16-3 described later.
Specifically, the thickness of the U-shaped second elastic portion 16-5 is smaller than the width thereof, and the second elastic portion 16-5 has a significantly different cross-sectional quadratic moment. Therefore, the second elastic portion 16-5 has high rigidity against the force in the Fz direction and low rigidity against the moment in the Mz direction. When torsion is considered, the flexibility of the second elastic portion 16-5 is assumed to be more than that of simply bending with respect to the force in the Fz direction. However, the rigidity of the second elastic portion 16-5 with respect to the force in the Fz direction is sufficiently higher than the moment in the Mz direction.
(function of third Structure 16-3)
The third structural body 16-3 is provided between the first elastic portion 16-4 and the relay portion 16-6, and is arranged in parallel with the strain sensor 19. Therefore, when the elastic body 16 is applied with the force in the Fx and Fy directions and/or the moment in the Mz direction, the displacement amounts in the thickness direction and the width direction of the strain body 19a constituting the strain sensor 19 can be controlled.
Specifically, the width W of the third structure 16-3 is larger than the thickness of the strain body 19a, and the thickness T of the third structure 16-3 is smaller than the width of the strain body 19a. Therefore, the third structure 16-3 can control the displacement amounts in the thickness direction and the width direction of the strain body 19a having different cross-sectional second order moments.
(Structure of Strain sensor)
Fig. 9 shows an example of the strain sensor 19. As described above, the strain sensor 19 is configured by the strain body 19a and the plurality of gauges R1 to R8 provided on the surface of the strain body 19a. The strain body 19a is made of metal and has a thickness smaller than a width. Therefore, the strain body 19a is easily deformed in the thickness direction and is hardly deformed in the width direction.
One end of the strain body 19a is provided to the first structure 16-1, and the other end is provided to the relay section 16-6 of the second structure 16-2. The gauges R1, R3, R5, and R8 are provided near one end portion of the strain body 19a, and the gauges R2, R4, R6, and R7 are provided near the other end portion of the strain body 19a.
Fig. 10 shows an example of a bridge circuit using the strain gauges R1 to R8. The gauges R1, R2, R3, and R4 constitute a first bridge circuit BC1, and the gauges R5, R6, R7, and R8 constitute a second bridge circuit BC2.
The first bridge circuit BC1 is configured by arranging a series circuit of the strain gauge R2 and the strain gauge R1 and a series circuit of the strain gauge R4 and the strain gauge R3 between the power supply V and the ground GND. An output voltage Vout + is output from the connection node between the gauge R2 and the gauge R1, and an output voltage Vout-is output from the connection node between the gauge R4 and the gauge R3. The output voltage Vout + and the output voltage Vout-are supplied to the operational amplifier OP1, and the output voltage Vout is output from the output terminal of the operational amplifier OP 1.
The second bridge circuit BC2 is configured by arranging a series circuit of the strain gauge R6 and the strain gauge R5 and a series circuit of the strain gauge R8 and the strain gauge R7 between the power supply V and the ground GND. An output voltage Vout + is output from the connection node between the gauge R6 and the gauge R5, and an output voltage Vout-is output from the connection node between the gauge R8 and the gauge R7. The output voltage Vout + and the output voltage Vout-are supplied to the operational amplifier OP2, and the output voltage Vout is output from the output terminal of the operational amplifier OP 2.
As described above, the strain body 19a is deformed into an S shape by a force in the Fz direction, for example, and thereby a large output voltage can be obtained from the first bridge circuit BC1 and the second bridge circuit BC2.
The arrangement of the strain gauges R1 to R8 with respect to the strain body 19a and the configuration of the bridge circuits BC1 and BC2 are not limited to this, and may be modified.
(effects of elastomer 16 and force sensor)
The elastic body 16 of the present embodiment includes: a first structure 16-1, a plurality of second structures 16-2, a second elastic section 16-5 provided to each of the second structures 16-2, a relay section 16-6 provided between the two second elastic sections 16-5, two third structures 16-3 provided to the relay section 16-6, and a first elastic section 16-4 provided to each of the third structures 16-3 and connected to the first structure 16-1, wherein the second elastic section 16-5 has a rigidity lower than that of the second structure 16-2, and the rigidity of the first elastic section 16-4 is equal to or lower than that of the second elastic section 16-5. Therefore, the rigidity of the entire elastic body 16 can be reduced as compared with the case without the first elastic portion 16-4 and the second elastic portion 16-5, and the displacement amount of the elastic body 16 can be increased with respect to the force in the Fx and Fy directions. Therefore, the displacement amount of the elastic body 16 can be increased compared to the extremely small deformation of the strain body 19a with respect to the force in the Fx and Fy directions.
In addition, the elastic body 16 of the present embodiment includes the first elastic portion 16-4, the second elastic portion 16-5, and the relay portion 16-6, so that the displacement amounts in the six-axis direction can be made substantially equal. Further, the third structural body 16-3 and the relay unit 16-6 can be suppressed from being deformed by the force in the Fz direction, and the first elastic unit 16-4, the third structural body 16-3 and the relay unit 16-6 can be deformed into a substantially S shape. Accordingly, the strain body 19a can be deformed in an S-shape, and therefore, a sufficient strain can be applied to the strain body 19a in response to the force in the Fz direction. Therefore, a large sensor output can be obtained, and a highly accurate force sensor can be configured.
Further, since the rigidity of the first elastic portion 16-4 is equal to or less than the rigidity of the second elastic portion 16-5, a larger strain can be applied to the force corresponding variation 19a in the Fz direction, and a larger sensor output can be obtained. Here, the rigidity includes axial rigidity, bending rigidity, shearing rigidity, and torsional rigidity.
The six-axis displacement of the elastic body 16 is substantially equal, and the overall rigidity is low. Therefore, the strain body 19a can be protected by the stopper 30 having a simple structure.
Specifically, in the case of an elastic body having high rigidity, it is necessary to set the gap between the side surface of the stopper member 31 of the stopper 30 and the inner surface of the opening 13a of the mounting plate 13 to 20 μm or less, for example. Therefore, the machining is difficult. However, as in the present embodiment, when the rigidity of the entire elastic body 16 is low, the displacement amount of the elastic body 16 at the rated load can be increased to, for example, 100 μm to 200 μm. Therefore, the distance between the side surface of the stopper member 31 and the inner surface of the opening 13a of the mounting plate 13 can be increased, and therefore, the stopper 30 can be easily designed when an overload occurs, and the stopper 30 can be easily machined.
In addition, since the stopper 30 having high rigidity can suppress displacement of the elastic body 16 and the strain body 19a at the time of overload, sufficient strain can be applied to the strain body 19a within the range of rated load. Therefore, a high sensor output can be obtained. If the stopper 30 is not provided, it is assumed that a rated load with a sufficient safety factor expected is required to be set at the time of overload. Therefore, sufficient strain cannot be applied to the strain body, and it is difficult to obtain a high sensor output.
(modification of elastomer 16)
Fig. 11 shows a modification of the elastic body 16.
In the above embodiment, the first elastic portion 16-4 is provided at one end portion (distal end portion) in the longitudinal direction of the third structural body 16-3 in a direction (width direction) intersecting the longitudinal direction, and has the bent portion 16-4a.
In contrast, in the modification shown in fig. 11, the first elastic portion 16-4 is formed by bending in the thickness direction of the metal plate at one end portion in the longitudinal direction of the third structural body 16-3. The first elastic portion 16-4 thus formed has a rigidity equal to or lower than that of the second elastic portion 16-5, and is configured to be easily deformed in the direction of arrow C, D.
The same effects as those of the above embodiment can be obtained by the above modified example.
In addition, the present invention is not limited to the above embodiments, and constituent elements may be modified and embodied in the implementation stage without departing from the spirit thereof. In addition, various inventions can be formed by appropriate combinations of a plurality of constituent elements disclosed in the above embodiments. For example, several components may be deleted from all the components shown in the embodiments. Further, the constituent elements according to the different embodiments may be appropriately combined.
Claims (8)
1. An elastomeric body, comprising:
a first structural body including a plurality of first elastic portions that are deformable in a six-axis direction;
a plurality of second structures having a second elastic portion that is deformable in the six-axis direction and a relay portion connected to the second elastic portion; and
a plurality of third structures provided between the relay section and each of the first elastic sections of the second structures,
the first structure, the second structure, the third structure, the relay portion, the first elastic portion, and the second elastic portion are formed of a single metal plate, and the second structure, the third structure, the relay portion, the first elastic portion, and the second elastic portion are formed of the bent metal plate.
2. The elastomer according to claim 1,
the rigidity of the first elastic portion is lower than the rigidity of the second elastic portion.
3. The elastomer according to claim 1,
the first elastic portion is provided at a part of the third structure in the width direction.
4. The elastomer according to claim 1,
the first elastic portion is provided at one end portion in the longitudinal direction of the third structure.
5. A force sensor, comprising:
a first structural body to which a plurality of first elastic portions that are deformable in a six-axis direction are connected;
a plurality of second structures each having a second elastic portion deformable in the six-axis direction and a relay portion connected to the second elastic portion;
a plurality of third structures provided between the relay section and each of the first elastic sections of the second structures; and
a plurality of strain sensors provided between the relay sections of the first structure and the second structure, respectively,
wherein the first structure, the second structure, the third structure, the relay portion, the first elastic portion, and the second elastic portion are formed of one metal plate,
the second structure, the third structure, the relay section, the first elastic section, and the second elastic section are the bent metal plates.
6. The force sensor of claim 5,
the rigidity of the first elastic portion is lower than the rigidity of the second elastic portion.
7. The force sensor of claim 5,
the first elastic portion is provided at a part of the third structure in the width direction.
8. The force sensor of claim 5,
the first elastic portion is provided at one end portion in the longitudinal direction of the third structure.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019-012326 | 2019-01-28 | ||
| JP2019012326A JP6999587B2 (en) | 2019-01-28 | 2019-01-28 | Elastic body and force sensor using it |
| PCT/JP2019/047067 WO2020158168A1 (en) | 2019-01-28 | 2019-12-02 | Elastic body and force sensor using same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113167670A CN113167670A (en) | 2021-07-23 |
| CN113167670B true CN113167670B (en) | 2023-02-17 |
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| CN201980078288.5A Active CN113167670B (en) | 2019-01-28 | 2019-12-02 | Elastic body and force sensor using same |
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| Country | Link |
|---|---|
| JP (1) | JP6999587B2 (en) |
| CN (1) | CN113167670B (en) |
| WO (1) | WO2020158168A1 (en) |
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Also Published As
| Publication number | Publication date |
|---|---|
| JP6999587B2 (en) | 2022-01-18 |
| WO2020158168A1 (en) | 2020-08-06 |
| CN113167670A (en) | 2021-07-23 |
| JP2020118647A (en) | 2020-08-06 |
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