WO2019187707A1 - トルクセンサ - Google Patents

トルクセンサ Download PDF

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Publication number
WO2019187707A1
WO2019187707A1 PCT/JP2019/004753 JP2019004753W WO2019187707A1 WO 2019187707 A1 WO2019187707 A1 WO 2019187707A1 JP 2019004753 W JP2019004753 W JP 2019004753W WO 2019187707 A1 WO2019187707 A1 WO 2019187707A1
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WO
WIPO (PCT)
Prior art keywords
torque
strain
sensor
strain sensor
stopper
Prior art date
Application number
PCT/JP2019/004753
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English (en)
French (fr)
Japanese (ja)
Inventor
嵩幸 遠藤
Original Assignee
日本電産コパル電子株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本電産コパル電子株式会社 filed Critical 日本電産コパル電子株式会社
Publication of WO2019187707A1 publication Critical patent/WO2019187707A1/ja

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating

Definitions

  • the embodiment of the present invention relates to a torque sensor provided at a joint of a robot arm, for example.
  • the torque sensor has a first structure to which torque is applied, a second structure to which torque is output, and a plurality of strain generating portions as beams that connect the first structure and the second structure.
  • a plurality of strain gauges as sensor elements are arranged in these strain generating portions. These strain gauges constitute a bridge circuit (see, for example, Patent Documents 1, 2, and 3).
  • the torque sensor can detect the torque up to the allowable strain of the strain gauge, the sensitivity can be increased, and a high-resolution or high-accuracy torque sensor can be obtained.
  • the safety factor is designed to be a value larger than 1, for example, in the range of about 3 to 5.
  • Safety and sensitivity are in a trade-off relationship, and when the safety factor is set large, the rated torque becomes small and the torque detection accuracy (sensitivity) decreases. Therefore, the accuracy of the torque sensor is reduced.
  • Embodiments of the present invention are intended to provide a torque sensor that can improve the accuracy of torque detection by preventing deterioration of a strain gauge.
  • the torque sensor according to the embodiment includes a first structure, a second structure, a plurality of third structures that connect the first structure and the second structure, the first structure, and the first structure. At least one strain sensor connected between two structures, one end is fixed to one of the first structure and the second structure, and the other end is the first structure and the second And at least one stopper that can be engaged with an engaging portion provided on the other side of the structure.
  • the embodiment of the present invention can provide a torque sensor that can prevent deterioration of a strain gauge and improve the accuracy of torque detection.
  • FIG. 4 is a perspective view of FIG. 3.
  • FIG. 8 is a cross-sectional view taken along the line VIIIA-VIIIA shown in FIG. 7 and is a view shown for explaining a cross-sectional secondary moment in a direction other than torque (Fz, Mx).
  • FIG. 8 is a cross-sectional view taken along line VIIIB-VIIIB shown in FIG.
  • the circuit diagram which shows an example of the bridge circuit of a 1st distortion sensor.
  • FIG. 17A is a diagram schematically illustrating a part of FIG.
  • FIG. 16 illustrating the operation of a stopper different from that of FIG. 17A.
  • the figure shown in order to demonstrate the relationship between the torque applied to a torque sensor, and the operation
  • FIG. 1 shows an example of a torque sensor 10 to which the present embodiment is applied.
  • the torque sensor 10 includes a first structure 11, a second structure 12, a plurality of third structures 13, a fourth structure 14, a fifth structure 15, stoppers 16 and 17, and a cover 18. is doing.
  • the first structure 11 and the second structure 12 are formed in an annular shape, and the diameter of the second structure 12 is smaller than the diameter of the first structure 11.
  • the second structure 12 is arranged concentrically with the first structure 11, and the first structure 11 and the second structure 12 are connected by a third structure 13 as a plurality of beam portions arranged radially.
  • the second structure 12 has a hollow portion 12a, and, for example, a wiring (not shown) is passed through the hollow portion 12a.
  • the first structure 11 is connected to, for example, a measurement target, and the plurality of third structures 13 transmit torque from the first structure 11 to the second structure 12.
  • the second structure 12 may be connected to the measurement target, and torque may be transmitted from the second structure 12 to the first structure 11 via the plurality of third structures 13.
  • the first structure 11, the second structure 12, and the plurality of third structures 13 are made of metal, for example, stainless steel. However, if sufficient mechanical strength can be obtained with respect to applied torque. It is also possible to use materials other than metals.
  • FIG. 2 shows a state where the stoppers 16 and 17 of FIG. 1 are removed.
  • a first strain sensor 19 and a second strain sensor 20 are provided between the first structure 11 and the second structure 12. That is, as will be described later, one end portions of the first strain sensor 19 and the second strain sensor 20 are joined to the first structure 11, and the other end portions of the first strain sensor 19 and the second strain sensor 20 are The two structures 12 are joined.
  • first strain sensor 19 and the second strain sensor 20 are disposed at positions symmetrical with respect to the centers of the first structure 11 and the second structure 12 (the center of torque action). In other words, the first strain sensor 19 and the second strain sensor 20 are arranged on the diameters of the annular first structure body 11 and second structure body 12.
  • the thickness of the first strain sensor 19 and the second strain sensor 20, that is, the thickness of the strain generating body described later is thinner than the thickness of the third structure 13.
  • the mechanical strength of the torque sensor 10 is set by the thickness and width of the third structure 13.
  • the strain body is provided with a plurality of strain gauges as sensor elements, and a bridge circuit is constituted by these sensor elements.
  • the stoppers 16 and 17 protect the mechanical deformation of the first strain sensor 19 and the second strain sensor 20 and have a function as a cover for the first strain sensor 19 and the second strain sensor 20. Details of the stoppers 16 and 17 will be described later.
  • the first strain sensor 19 is connected to the flexible substrate 21, and the second strain sensor 20 is connected to the flexible substrate 22.
  • the flexible boards 21 and 22 are connected to a printed board (not shown) covered by the cover 18.
  • An operational amplifier that amplifies an output voltage of a bridge circuit, which will be described later, is disposed on the printed circuit board. Since the circuit configuration is not the essence of this embodiment, the description is omitted.
  • FIGS. 3 and 4 show the first embodiment.
  • the first strain sensor 19 and the second strain sensor 20, the flexible substrates 21 and 22, the cover 18 and the like are removed from FIGS. Only the structure 11, the second structure 12, the plurality of third structures 13, the fourth structure 14, and the fifth structure 15 are shown.
  • the strain generating bodies of the first strain sensor 19 and the second strain sensor 20 are used.
  • strain is not concentrated on a plurality of strain gauges as sensor elements.
  • the fourth structure 14 and the fifth structure 15 are provided at positions symmetrical with respect to the centers of the first structure 11 and the second structure 12, and the fourth structure 14 includes the first structure 14 and the first structure 11.
  • the structure 11 has a recess 14 f continuous from the second structure 12, and the fifth structure 15 has a recess 15 f continuous from the first structure 11 to the second structure 12.
  • the first strain sensor 19 is disposed in the recess 14 f of the fourth structure 14, and the second strain sensor 20 is disposed in the recess 15 f of the fifth structure 15.
  • the number of strain sensors may be three or more. In this case, the number of structures may be increased according to the number of strain sensors.
  • the fourth structure 14 includes a first connection part 14 a and a second connection part 14 b as joint parts for joining the first strain sensor 19, and a third connection part 14 c and a fourth part as beams. It has the connection part 14d and the opening part 14e enclosed by the 1st connection part 14a, the 2nd connection part 14b, the 3rd connection part 14c, and the 4th connection part 14d.
  • the fourth structure 14 is a beam having an opening 14 e provided between the first structure 11 and the second structure 12.
  • the first connection portion 14a extends from the first structure 11 to the second structure 12 side.
  • the second connection portion 14b extends from the second structure 12 to the first structure 11 side.
  • the 3rd connection part 14c and the 4th connection part 14d as a beam are provided between the 1st connection part 14a and the 2nd connection part 14b.
  • the length L1 of the third connection portion 14c and the fourth connection portion 14d is shorter than the length L2 (also shown in FIG. 1) of the third structure 13 as a beam.
  • a width W1 in the torque (Mz) direction of the third connection portion 14c and the fourth connection portion 14d is narrower than a width W2 in the torque direction of the first connection portion 14a and the second connection portion 14b, and the third connection portion 14c and the fourth connection portion 14c.
  • the total width W1 of the connecting portion 14d is narrower than the width W3 (shown in FIG. 1) of the third structure 13 in the torque (Mz) direction. For this reason, the stiffness in the torque direction of the third connection portion 14c and the fourth connection portion 14d is lower than the stiffness in the torque direction of the first connection portion 14a, the second connection portion 14b, and the third structure 13.
  • the thickness in the Fz direction of the third connection portion 14c and the fourth connection portion 14d is equal to the thickness in the Fz direction of the first structure body, the second structure body, and the third structure body. Furthermore, the sum of the length L11 of the first connection portion 14a, the length L12 of the second connection portion 14b, and the length L1 of the third connection portion 14c and the fourth connection portion 14d is the length of the third structure 13. Is equal to For this reason, the rigidity in the Fz direction of the third connection part 14c and the fourth connection part 14d is slightly smaller than the rigidity of the third structure 13 in the Fz direction.
  • the first connection portion 14a and the first structure 11 constitute a high-rigidity portion HS1
  • the second connection portion 14b and the second structure 12 Constitutes the high-rigidity portion HS2.
  • the third connection portion 14c constitutes the low rigidity portion LS1
  • the fourth connection portion 14d constitutes the low rigidity portion LS2.
  • the total of the length L11 of the first connection portion 14a, the length L12 of the second connection portion 14b, and the length L1 of the third connection portion 14c and the fourth connection portion 14d is the length of the third structure 13. Is not limited to the case of being equal to each other.
  • the first connection portion 14a has the above-described recess 14f.
  • the thickness of the recess 14 f is thinner than the thickness of the first to third structures 11, 12, and 13.
  • first strain sensor 19 One end of the first strain sensor 19 is connected to the recess 14f of the first connection portion 14a, and the other end is connected to the recess 14f of the second connection portion 14b. For this reason, the first strain sensor 19 straddles the opening 14e. As will be described later, the bottom of the recess 14f is positioned below the center of the thickness of the fourth structure 14, and the surface of the strain-generating body constituting the first strain sensor 19 is the first structure 11 and the second structure. 12, a plane including the center of gravity of the structure including the plurality of third structures 13, the fourth structure 14, and the fifth structure 15.
  • FIG. 6A and 6B are diagrams schematically showing FIG. 5, FIG. 6A shows a case where a force in the torque (Mz) direction is applied to the torque sensor 10, and FIG. 6B shows a case other than torque on the torque sensor 10. The case where the force of the direction of (Fz, Mx) is applied is shown.
  • the first strain sensor 19 (second strain) is applied when a force in a direction other than torque (Fz, Mx) is applied.
  • the deformation of the sensor 20) occurs in the range of the length L2, and the strain can be prevented from concentrating on a plurality of strain gauges as sensor elements provided on the strain generating body of the first strain sensor 19. It is possible to prevent a decrease in detection accuracy of the sensor 19 (second strain sensor 20).
  • FIG. 7 schematically shows the fourth structure 14.
  • the secondary moment of inertia (ease of deformation) of the fourth structure 14 and the conditions required for the fourth structure 14 (fifth structure 15) will be described.
  • the ratio of the cross-sectional secondary moment of the high-rigidity part HS1 in the torque (Mz) direction to the cross-sectional secondary moments of the low-rigidity parts LS1 and LS2 is expressed by the following equation (1).
  • the deformation concentration level of the low rigidity portions LS1 and LS2 when a force in the torque (Mz) direction is applied is greater than the deformation concentration level of the low rigidity portions LS1 and LS2 when a force in a direction other than the torque (Fz) is applied.
  • the condition required for the fourth structure 14 (the fifth structure 15) is that the relationship represented by the following expression (3) is satisfied.
  • FIG. 8A is a cross-sectional view along the line VIIIA-VIIIA shown in FIG. 7, and shows an example of the dimension of the high-rigidity portion HS1.
  • FIG. 8B is a cross-sectional view taken along the line VIIIB-VIIIB shown in FIG. 7, and shows an example of dimensions of the low-rigidity portions LS1 and LS2.
  • the cross-sectional secondary moment Is regarding the axis N1-N1 is as follows: It is.
  • the axis N1-N1 is an axis passing through the center in the thickness direction of the high rigidity portion HS1.
  • the cross-sectional secondary moment Is regarding the axis N2-N2 is It is as follows.
  • the axis N2-N2 is an axis passing through the center in the thickness direction of the low-rigidity portions LS1, LS2.
  • the cross-sectional secondary moment Iw ′ of a structure having a rectangular cross-section is expressed by the following equation (5).
  • the cross-sectional secondary moment Js with respect to the axis N3-N3 is as follows. is there.
  • the axis N3-N3 is an axis passing through the center in the width direction of the high rigidity portion HS1.
  • FIG. 8H shows the positional relationship between the recess 14f and the first strain sensor 19 (strain body).
  • the bottom of the recess 14f is located at the center H / 2 or less of the thickness of the fourth structure 14.
  • the surface of the strain-generating body constituting the first strain sensor 19 is formed on the first structure 11, the second structure 12, the plurality of third structures 13, the fourth structure 14, and the fifth structure. Therefore, the bottom of the recess 14f is lower than the surface CG including the center of gravity of the fourth structure 14 by the thickness of the strain generating body.
  • This position is a neutral plane, and no compressive force or tensile force is applied to the strain generating body. For this reason, it is possible to reduce the strain in the bending direction of the strain generating body, that is, in the direction other than the torque (Fz).
  • the fourth structure 14 provided with the first strain sensor 19 and the fifth structure 15 provided with the second strain sensor 20 are in the torque (Mz) direction and other than the torque (Fz, respectively).
  • Mx acts as a high rigidity portion with respect to the force in the direction of Mx), and acts as a low rigidity portion with respect to the force in the torque (Mz) direction, and other than torque (Fz , Mx) is provided with a third connection portion 14c and a fourth connection portion 14d that act as a highly rigid portion with respect to the force in the direction of Mx).
  • FIG. 9 shows a comparative example of the torque sensor 10.
  • the torque sensor 30 shown in FIG. 9 is different from the torque sensor 10 shown in the first embodiment in the configuration of the connecting portion between the first strain sensor 19 and the second strain sensor 20, and other configurations are the same as those in the first embodiment. It is the same.
  • one end of the first strain sensor 19 and the second strain sensor 20 is connected to the protrusion 11-1 provided on the first structure 11, and the other end is connected to the second structure 12.
  • Each is connected to the provided protrusion 12-1.
  • the protrusions 11-1 and 12-1 have a thickness equivalent to, for example, the first structure 11 and the second structure 12.
  • the distance between the protrusion 11-1 and the protrusion 12-1 is equal to the length L1 of the third connection portion 14c and the fourth connection portion 14d shown in FIG.
  • the torque sensor 30 as a comparative example, only the third structure 13 acts as a high-rigidity part with respect to forces in the torque direction and directions other than torque, and the first strain sensor 19 and the second strain sensor 20 are the first Only the strain body is provided between the structure 11 and the second structure 12. For this reason, the first strain sensor 19 and the second strain are applied to the torque sensor 30 in either direction when a force in the torque (Mz) direction is applied or when a force in a direction other than the torque (Fz, Mx) is applied. The strain is concentrated on the strain gauge provided on the strain body of the strain sensor 20.
  • FIG. 10A and FIG. 10B are diagrams schematically showing FIG. 9, FIG. 10A shows a case where a torque (Mz) direction force is applied to the torque sensor 30, and FIG. The case where the force of the direction of (Fz, Mx) is applied is shown.
  • FIG. 11 shows distortions when the same force is applied in the respective axial directions of the torque sensor 10 according to the first embodiment and the torque sensor 30 according to the comparative example.
  • the distortion with respect to the force in the torque (Mz) direction is larger than in the comparative example, and other than the torque (Fx, Fy, Fz, Mx, My ) Is less strained than the comparative example.
  • the strain with respect to forces in the Fz and Mx directions can be significantly reduced compared to the comparative example. Therefore, according to the first embodiment, the first strain sensor 19 and the second strain sensor 20 can be reduced in distortion due to a force in a direction other than the torque, and the detection accuracy of the first strain sensor 19 and the second strain sensor 20 can be reduced. It is possible to prevent the decrease.
  • the surface of the strain generating body constituting the first strain sensor 19 includes the first structure 11, the second structure 12, the plurality of third structures 13, the fourth structure 14, and the fifth structure 15. It is located on the plane CG including the center of gravity of the structure. For this reason, it is possible to reduce the strain in the bending direction of the strain generating body, that is, in the direction other than the torque (Fz).
  • FIG. 12 shows a second embodiment.
  • the first strain sensor 19 is provided in the fourth structure 14, and the second strain sensor 20 is provided in the fifth structure 15. Since the first strain sensor 19 and the second strain sensor 20 have the same configuration, only the configuration of the first strain sensor 19 will be described.
  • the first strain sensor 19 includes a strain body 41 and a plurality of strain gauges 51, 52, 53, 54 as sensor elements arranged on the surface of the strain body 41.
  • the strain body 41 is made of a rectangular metal plate, for example, stainless steel (SUS).
  • the thickness of the strain body 41 is thinner than the thickness of the third structure 13.
  • the strain gauges 51, 52, 53, 54 are constituted by, for example, Cr—N thin film resistors provided on the strain generating body 41.
  • the material of the thin film resistor is not limited to Cr—N.
  • the strain body 41 has one end connected to the first connecting portion 14a and the other end connected to the second connecting portion 14b.
  • a connection method between the strain body 41 and the first connection portion 14a and the second connection portion 14b for example, a connection method using welding, screwing, or an adhesive can be used.
  • the effective length of the strain body 41 corresponds to the length between the location connected to the first connection portion 14a and the location connected to the second connection portion 14b.
  • the plurality of strain gauges 51, 52, 53, 54 are arranged in the region AR 1 on the second structure 12 side from the central portion CT of the effective length of the strain body 41 in the strain body 41.
  • This region AR1 is a region where a large strain is generated in the strain generating body 41 within the range of the opening 14e.
  • this area AR1 is an area where the sensitivity of the first strain sensor 19 with respect to forces in directions other than torque, for example, Fx and My directions, and the sensitivity of the first strain sensor 19 in the torque (Mz) direction are the same. It is.
  • the strain gauges 51, 52, 53, 54 are arranged along the two diagonal lines DG1, DG2 of the strain body 41 in the longitudinal direction of the strain gauges 51, 52, 53, 54 in the area AR1. That is, the strain gauges 51 and 52 are arranged along one diagonal line DG1 whose longitudinal direction is indicated by a broken line, and the strain gauges 53 and 54 are arranged along the other diagonal line DG2 whose longitudinal direction is indicated by a broken line. .
  • the diagonal lines DG1 and DG2 correspond to rectangular regions located in the opening 14e of the strain generating body 41.
  • the strain gauges 51, 52, 53, and 54 of the first strain sensor 19 constitute one bridge circuit, and the strain gauges 51, 52, 53, and 54 of the second strain sensor 20 also constitute one bridge circuit. For this reason, the torque sensor 10 includes two bridge circuits.
  • FIG. 13 shows an example of the bridge circuit 50 of the first strain sensor 19.
  • the second strain sensor 20 also includes a bridge circuit having the same configuration as the bridge circuit 50.
  • Each of the output voltage of the bridge circuit 50 of the first strain sensor 19 and the output voltage of the bridge circuit 50 of the second strain sensor 19 is compensated for offset, temperature, and the like using software (not shown), for example. Thereafter, the output voltage of the bridge circuit 50 of the first strain sensor 19 and the output voltage of the bridge circuit 50 of the second strain sensor 19 are integrated and output as a detection voltage of the torque sensor 10. Compensation for offset, temperature, etc. is not limited to software, but can also be performed by hardware.
  • a series circuit of a strain gauge 52 and a strain gauge 53 and a series circuit of a strain gauge 54 and a strain gauge 51 are arranged between the power supply Vo and the ground GND.
  • the output voltage Vout + is output from the connection node between the strain gauge 52 and the strain gauge 53
  • the output voltage Vout ⁇ is output from the connection node between the strain gauge 54 and the strain gauge 51.
  • the output voltage Vout + and the output voltage Vout ⁇ are supplied to the operational amplifier OP, and the output voltage Vout is output from the output terminal of the operational amplifier OP.
  • R1 is the resistance value of the strain gauge 51
  • R2 is the resistance value of the strain gauge 52
  • R3 is the resistance value of the strain gauge 53
  • R4 is the resistance value of the strain gauge 54.
  • the output voltage Vout is output from the bridge circuit 50 by changing the resistance values of R1 to R4.
  • the output voltage of the bridge circuit 50 of the second strain sensor 20 is a voltage whose polarity is opposite to that of the bridge circuit 50 of the first strain sensor 19. For this reason, the output voltage in each bridge circuit 50 has the same absolute value and is different in positive and negative, so that they are canceled out and the detected voltage becomes 0V.
  • the strain gauges 51, 52, 53, and 54 as the sensor elements have the same displacement amount in the torque (Mz) direction and the directions other than the torque (Fx, My), they can output the same voltage. preferable.
  • the strain gauges 51, 52, 53, and 54 are regions in which the strain of the strain generating body 41 is equal in the torque (Mz) direction and directions other than the torque (Fx, My) (regions in which the sensitivity of measurement is equal). It is preferable to arrange
  • FIG. 14 schematically shows the state of the strain generating body 41 when a torque (Mz) direction force is applied to the torque sensor 10 and when a force other than the torque (Fx, My) direction is applied. ing.
  • the difference from the strain of the strain generating body 41 in the case is that in the region AR2 of the strain generating body 41, the strain of the strain generating body 41 when a force in the torque (Mz) direction is applied and other than the torque (Fx, My) It is smaller than the difference from the strain of the strain generating body 41 when a force in the direction of is applied.
  • the difference between the detection sensitivity of torque (Mz) and the detection sensitivity of other than torque (Fx, My) is as small as less than 1%.
  • the difference between the detection sensitivity of torque and the detection sensitivity other than torque is several percent. Therefore, it is preferable to arrange a plurality of strain gauges 51, 52, 53, 54 in the area AR1 on the second structure 12 side.
  • each of the first strain sensor 19 and the second strain sensor 20 includes the first structure 11 and the strain body 41 connected between the second structure 12 and A plurality of strain gauges 51, 52, 53, and 54 as sensor elements provided on the strain generating body 41 are provided, and the plurality of strain gauges 51, 52, 53, and 54 are center portions in the longitudinal direction of the strain generating body 41. It arrange
  • the region AR1 of the strain generating body 41 includes strain (sensitivity) (a1, a2) when a force in the torque direction is applied to each of the first strain sensor 19 and the second strain sensor 20, and a direction other than the torque.
  • the bridge circuit 50 arranged in the region AR1 of the strain generating body 41 has a small difference in detection sensitivity with respect to the force in the torque direction and the force in the direction other than the torque, the first strain sensor 19 and the second strain sensor 20 The output voltage error is also small. For this reason, when the voltages output from the two bridge circuits 50 are calibrated, the detection errors other than the torque can be calibrated only by calibrating the detection error with respect to the torque. Therefore, since it is not necessary to provide another strain sensor to detect a force in a direction other than torque (Fx, My), the calibration time can be shortened and a high-speed response can be realized.
  • FIG. 15 schematically shows a torque sensor 60 according to a comparative example.
  • the torque sensor 60 includes a first strain sensor 61 and a second strain sensor 62 between the first structure 11 and the second structure 12.
  • the first strain sensor 61 and the second strain sensor 62 each have a strain body 63, and each of the strain bodies 63 includes a plurality of strain gauges 51, 52, 53, and 54 that form a bridge circuit shown in FIG. Is arranged. Since FIG. 15 is a schematic diagram, the third structure 13 is omitted.
  • the arrangement of the strain gauges 51, 52, 53, 54 is different from that of the second embodiment. That is, the strain gauges 52 and 53 are disposed in the region of the strain body 63 on the first structure 11 side, and the strain gauges 51 and 54 are disposed in the region of the strain body 63 on the second structure 12 side. Yes.
  • the strain gauges 52 and 53 arranged in the region on the first structure 11 side are arranged in the torque (Mz) direction and the directions other than the torque (Fx, My). Distortion is different. Therefore, the sensitivity of the first strain sensor 61 and the sensitivity of the second strain sensor 62 when a force in the torque (Mz) direction is applied, and the force in a direction other than the torque (Fx, My) are applied. The difference between the sensitivity of the first strain sensor 61 and the sensitivity of the second strain sensor 62 is large.
  • the torque sensor 60 outputs an error consisting of an average value of the first strain sensor 61 and the second strain sensor 62.
  • the torque sensor 10 of the second embodiment when a force in a direction other than torque (Fx, My) is applied to the torque sensor 10, the sensitivity in the direction other than torque (Fx, My) is torque (Mz ) Coincides with the direction sensitivity. Therefore, the output voltage value (positive value) (Vout1) of the first strain sensor 19 and the output voltage value (negative value) ( ⁇ Vout2) of the second strain sensor 20 are substantially equal (
  • the torque sensor 60 according to the comparative example In the case of the torque sensor 60 according to the comparative example, the errors in the output voltages of the first strain sensor 61 and the second strain sensor 62 are large (
  • the second embodiment is not limited to the structure of the torque sensor 10, and the strain gauges 51, 52, 53, and 54 may be disposed in the area AR1. For this reason, even if the arrangement according to the second embodiment is applied to a torque sensor 30 having a structure as shown in FIG. 9, for example, the same effect as that of the second embodiment can be obtained.
  • FIG. 16 shows a third embodiment, and shows an enlarged portion indicated by B in FIG.
  • the first strain sensor 19 is covered with the stopper 16, and the second strain sensor 20 is covered with the stopper 17.
  • the stopper 16 and the stopper 17 are made of, for example, stainless steel or an iron-based alloy.
  • the stopper 16 and the stopper 17 prevent mechanical deformation of the first strain sensor 19 and the second strain sensor 20, and protect the strain gauges 51, 52, 53, and 54. Further, the stopper 16 and the stopper 17 also serve as a waterproof cover for the first strain sensor 19 and the second strain sensor 20. Description of a specific waterproof structure is omitted.
  • the stopper 16 has one end portion 16a and the other end portion 16b, and the width of the other end portion 16b of the stopper 16 is narrower than the width of the one end portion 16a.
  • One end 16a of the stopper 16 is, for example, press-fitted and fixed in a recess 14f as an engaging portion formed on the second structure 12 side of the fourth structure 14.
  • the other end 16 b of the stopper 16 is disposed in a recess 14 f formed on the first structure 11 side of the fourth structure 14.
  • the width of the other end 16b of the stopper 16 is narrower than the width of the recess 14f provided on the first structure 11 side.
  • Each GP is provided.
  • the gap GP is determined by the rigidity of the third structure 13 and the rated torque.
  • the gap GP is set to, for example, 10 ⁇ m.
  • FIG. 17A and FIG. 17B show the operation of the stopper, and a part of FIG. 16 is schematically shown.
  • a predetermined gap GP is provided between both sides of the other end 16b of the stopper 16 and the recess 14f.
  • the first structure 11 moves relative to the second structure 12, and a voltage corresponding to the torque applied from the first strain sensor 19. Is output.
  • the first strain sensor 19 returns due to elastic deformation.
  • FIG. 18 is a diagram for explaining the relationship between the torque as a load applied to the torque sensor 10 and the operation of the stopper 16.
  • the output voltage is schematically shown.
  • the first strain body 11 of the first strain sensor 19 (second strain sensor 20) has the second structure.
  • a voltage corresponding to the applied torque is output from the first strain sensor 19 (second strain sensor 20) while moving relative to the body 12.
  • the side surface of the recess 14f comes into contact with the stopper 16, and the deformation of the plurality of third structures 13 is suppressed by the rigidity of the stopper 16 (stopper 17). Accordingly, deformation of the strain generating body 41 is suppressed. That is, the operating point Op of the stopper 16 is set equal to the rated torque of the torque sensor 10, and the stopper 16 protects the strain generating body 41 against a torque larger than the rated torque.
  • the first strain sensor 19 and the second strain sensor 20 are provided with the stopper 16 as a cover, and the one end 16a of the stopper 16 is fixed in the recess 14f on the second structure 12 side.
  • the torque sensor 10 is applied with a torque larger than the rated torque, the other end portion 16b contacts the side surface of the recess 14f on the first structure 11 side. For this reason, it is possible to protect the first strain sensor 19 and the second strain sensor 20. Further, the structures other than the first strain sensor 19 and the second strain sensor 20 are also protected from plastic deformation and the like, similarly to the first strain sensor 19 and the second strain sensor 20.
  • the rated torque of the torque sensor 10 can be brought close to the 0.2% proof stress of the strain gauge. For this reason, the output voltage of the bridge circuit 50 at the rated torque can be increased. Therefore, it is possible to provide a high resolution and high accuracy torque sensor.
  • FIG. 19 shows the relationship between strain and stress of the strain gauge.
  • the strain gauge is designed with a safety factor against impact and fatigue set to about 3 to 5.
  • the safety factor is 3, the strain gauge stress is set to 1/3 of the 0.2% proof stress.
  • the rated torque is also set to 1/3 of the breaking torque.
  • the rated torque of the strain gauge can be set larger than that of a general torque sensor that does not have the stopper 16 and the stopper 17. Therefore, it is possible to provide a high resolution and high accuracy torque sensor.
  • FIG. 20 shows a first modification of the third embodiment.
  • the stopper 16 protects the first strain sensor 19 by the other end portion 16b coming into contact with the side surface of the recess 14f on the first structure 11 side.
  • the other end 16b of the stopper 16 has an opening 16b-1, and is inserted into the opening 16b-1 on the first structure 11 side of the fourth structure 14.
  • a protrusion 14g is provided.
  • a gap GP1 is provided between the opening 16b-1 and the protrusion 14g. The dimension of the gap GP1 is, for example, smaller than the dimension of the gap GP. Therefore, when a torque larger than the allowable torque is applied to the torque sensor 10, the first strain sensor 19 can be protected by the protrusion 14g coming into contact with the opening 16b-1 of the stopper 16.
  • the stopper 17 of the second strain sensor 20 has the same configuration as the stopper 16.
  • the same effect as that of the third embodiment can be obtained by the first modification. Moreover, according to the first modification, it is possible to further protect the first strain sensor 19 (second strain sensor 20) by the protrusion 14g contacting the opening 16b-1 of the stopper 16. .
  • FIG. 21 shows a second modification of the third embodiment.
  • the third embodiment includes the stopper 16 and the stopper 17, whereas the second modification further includes four stoppers 16-1, 16-2, 17-1, 17-2. It has.
  • the structures of the stoppers 16-1, 16-2, 17-1, and 17-2 are the same as the stoppers 16 and 17.
  • the same effect as that of the third embodiment can be obtained by the second modification.
  • the second modification since the number of stoppers is larger than that in the third embodiment, the first strain sensor 19 and the second strain sensor 20 can be further protected.
  • the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.
  • various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
  • the torque sensor of this embodiment is applied to a joint of a robot arm, for example.
  • SYMBOLS 10 Torque sensor, 11 ... 1st structure, 12 ... 2nd structure, 13 ... 3rd structure, 14 ... 4th structure, 14a ... 1st connection part, 14b ... 2nd connection part, 14c ... 1st 3 connection part, 14d ... 4th connection part, 14e ... opening part, 14f ... recessed part (engagement part), 14g ... projection, 15 ... 5th structure, 16, 16-1, 16-2 ... stopper, 16b- DESCRIPTION OF SYMBOLS 1 ... Opening part, 17, 17-1, 17-2 ... Stopper, 19 ... 1st strain sensor, 20 ... 2nd strain sensor, 41 ... Strain body, GP, GP1 ... Gap, 51, 52, 53, 54 ... Strain gauge as a sensor element.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)
  • Manipulator (AREA)
  • Power Steering Mechanism (AREA)
PCT/JP2019/004753 2018-03-29 2019-02-08 トルクセンサ WO2019187707A1 (ja)

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JPS5376882U (zh) * 1976-11-29 1978-06-27
JP2002502962A (ja) * 1998-02-04 2002-01-29 エス．エヌ．エール．ルールマン 回転シャフトのためのトルクセンサ
JP2005084000A (ja) * 2003-09-11 2005-03-31 Nissan Motor Co Ltd トルク計測装置
EP2322905A1 (de) * 2009-11-16 2011-05-18 Baumer Innotec AG Kraftmesszelle zur Messung der Einspritzkraft beim Spritzgiessen
JP2017172983A (ja) * 2016-03-18 2017-09-28 株式会社安川電機 ロボット及びトルクセンサ

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CN101118194A (zh) * 2007-09-14 2008-02-06 哈尔滨工业大学 提供转矩和弯矩过载保护的关节力矩传感器

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Publication number Priority date Publication date Assignee Title
JPS5376882U (zh) * 1976-11-29 1978-06-27
JP2002502962A (ja) * 1998-02-04 2002-01-29 エス．エヌ．エール．ルールマン 回転シャフトのためのトルクセンサ
JP2005084000A (ja) * 2003-09-11 2005-03-31 Nissan Motor Co Ltd トルク計測装置
EP2322905A1 (de) * 2009-11-16 2011-05-18 Baumer Innotec AG Kraftmesszelle zur Messung der Einspritzkraft beim Spritzgiessen
JP2017172983A (ja) * 2016-03-18 2017-09-28 株式会社安川電機 ロボット及びトルクセンサ

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