JP2012189516A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor capable of accurately measuring torque.SOLUTION: A torque sensor 1 according to an embodiment of the present invention includes: a first member 11, a second member 12, a connection member 13, a scale 14, and a detection head 15. A torque sensor 1 further includes a first connection part 16 which connects the scale 14 with the detection head 15, allows displacement of the detection head 15 in the direction in parallel with a first line L1 to the scale 14, and restricts the displacement in other directions; and a second connection part 17 which connects the first member 11 with the scale 14, or connects the second member 12 with the detection head 15, restricts the displacement of the scale 14 to the first member 11, or restricts the displacement of the detection head 15 to the second member 12 in the direction in parallel with the first line L1, and allows the displacement in other directions.

Description

  The present invention relates to a torque sensor, and more particularly to a linear encoder type torque sensor.

  The torque sensor is often provided at a joint portion of a robot or the like. Among such torque sensors, a linear encoder type torque sensor is configured as shown in FIG. 13, for example.

  A torque sensor 100 shown in FIG. 13 includes a first disk 110, a second disk 120, a connecting member 130, a scale 140, and a detection head 150. The first disk 110 is connected to an input shaft of a robot arm, for example. The first disc 110 is disposed substantially parallel to a plane including the X axis and the Y axis. The second disk 120 is connected to an output shaft such as a reduction gear mounted on the joint of the robot, for example. The second disc 120 is also disposed substantially parallel to a plane including the X axis and the Y axis. The first disc 110 and the second disc 120 are rotated relative to each other about the connecting member 130 (that is, around the Z axis) by the connecting member 130 arranged in parallel with the Z axis. Is allowed.

  The scale 140 is provided on the first disc 110. A plurality of tracks are shown in the longitudinal direction of the scale 140. The longitudinal direction of the scale 140 is arranged in the X-axis direction.

  The detection head 150 is provided on the second disk 120. This detection head 150 is disposed immediately above the scale 140.

  As a result, when the first disk 110 and the second disk 120 rotate relative to each other about the connecting member 130, the detection head 150 moves on the scale 140 to read the track, and the detection head 150 And the relative displacement amount of the scale 140 is detected. And the detection head 150 outputs the said relative displacement amount to the processing apparatus which abbreviate | omitted illustration. The processing device calculates a torque acting between the first disc 110 and the second disc 120 based on the input relative displacement amount, the elastic coefficient of the connecting member 130, and the like. At this time, since the first disk 110 and the second disk 120 are relatively rotated around the connecting member 130, it is necessary to measure the displacement amount on the arc accurately. Since the rotation angle is very small, even if the linear displacement in the tangential direction of the rotational motion is measured by a linear encoder, the deterioration in accuracy is negligibly small.

By the way, Patent Documents 1 to 3 disclose techniques for calculating torque using other configurations.
In Patent Document 1, the brake lining that contacts the drum surface of the rotating drum is supported by a leaf spring, and the amount of deflection of the leaf spring when the brake lining contacts the rotating rotating drum is measured. Based on the measurement result The torque acting on the rotating drum is calculated.

  In Patent Literature 2, an input side steering shaft and a disk provided on an output side steering shaft are connected by radially arranged leaf springs, and the amount of deflection of the leaf springs is measured. Based on the result, the torque acting on the steering shaft is calculated.

In Patent Document 3, a shaft portion and a fixed portion are connected by a strain gauge, a deflection amount of the strain gauge is measured, and a torque acting on the shaft portion is calculated based on the measured result. Here, the shaft portion and the fixed portion are connected by a leaf spring so that the shaft portion does not generate eccentricity or non-coaxial with respect to the fixed portion.
However, the techniques disclosed in Patent Documents 1 to 3 are not linear encoder type torque sensor techniques.

Japanese Patent Publication No. 5-62937 JP-A-6-229849 Japanese Utility Model Publication No. 63-48131

  Since the connecting member 130 is an elastic member, the torque sensor 100 shown in FIG. 13 is affected by disturbances other than torque around the Z axis, as shown in FIG. Causes relative displacement other than rotation around the Z axis, and the relative distance and parallelism between the scale 140 and the detection head 150 cannot be maintained (FIG. 15). Here, FIG. 15 shows a measurement error of the torque sensor 100. From FIG. 15, it can be seen that the error should be horizontal in the vicinity of 0, but an error has occurred. Therefore, the torque sensor 100 shown in FIG. 13 has a problem that the torque cannot be measured with high accuracy.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a torque sensor capable of accurately measuring torque.

  The torque sensor according to the first aspect of the present invention is a linear encoder type torque sensor, and is disposed so as to face the first member and the first member, and is relative to the first member. A second member in a rotational relationship, a connecting member for connecting the first member and the second member, a plurality of tracks, and a first line extending in a direction in which the tracks extend And a scale provided in the first member so that a second line connecting the first line and the central axis of the connecting member is orthogonal, and provided in the second member, A detection head for detecting position information from a scale; and the scale and the detection head are connected to each other, the displacement of the detection head with respect to the scale in a direction parallel to the first line is allowed, and the detection with respect to the scale is performed. Parallel to the first line of the head A first connecting portion that restrains displacement in a direction other than the direction, the first member and the scale, or the second member and the detection head, and the scale with respect to the first member; Alternatively, the displacement of the detection head relative to the second member in a direction parallel to the first line is constrained, the scale relative to the first member, or the first of the detection head relative to the second member. A second connecting portion that allows displacement in a direction other than a direction parallel to the line.

  In the torque sensor according to a second aspect of the present invention, in the above torque sensor, the first connecting portion includes a plate-like member, and the surface of the plate-like member having the largest area is the second line. And a third line that is the central axis of the connecting member.

  The torque sensor according to a third aspect of the present invention is the above torque sensor, wherein the second connecting portion has a rigidity in a direction parallel to the first line higher than a rigidity of the first connecting portion. The rigidity in a direction other than the direction parallel to the first line is lower than the rigidity of the first connecting portion.

  The torque sensor according to a fourth aspect of the present invention is the above torque sensor, wherein the second connecting portion includes a sheet-like elastic member.

  A torque sensor according to a fifth aspect of the present invention is the above torque sensor, wherein the second connecting portion includes a sheet metal elastic member.

  The torque sensor according to a sixth aspect of the present invention is the torque sensor according to the first aspect, wherein the second connection portion includes a pin provided on the scale or the detection head, and the pin is inserted, Alternatively, a movable portion that extends in parallel with the second line in the second member is provided.

  The torque sensor according to a seventh aspect of the present invention is the above torque sensor, wherein the second connecting portion is an elastic member disposed in parallel with the first line between the pin and the movable portion. Is provided.

  As described above, according to the present invention, it is possible to provide a torque sensor that can accurately measure torque.

It is a front view showing roughly the torque sensor concerning Embodiment 1 of the present invention. It is a left view which shows roughly the torque sensor which concerns on Embodiment 1 of this invention. It is a top view which shows roughly the torque sensor which concerns on Embodiment 1 of this invention. It is a front view which shows roughly the time of a deformation | transformation of the torque sensor which concerns on Embodiment 1 of this invention. It is a front view which shows schematically the torque sensor which concerns on Embodiment 2 of this invention. It is a left view which shows roughly the torque sensor which concerns on Embodiment 2 of this invention. It is a bottom view which shows roughly the torque sensor which concerns on Embodiment 2 of this invention. It is a left view which shows roughly the time of a deformation | transformation of the torque sensor which concerns on Embodiment 2 of this invention. It is a front view which shows schematically the torque sensor which concerns on other embodiment. It is a partial left view which shows roughly the torque sensor which concerns on other embodiment. It is a left view which shows roughly the torque sensor which concerns on other embodiment. It is a left view which shows roughly the torque sensor which concerns on other embodiment. It is a left view which shows the related torque sensor schematically. It is a figure which shows roughly a mode that the 2nd disc with respect to the 1st disc in the related torque sensor was displaced by external forces other than the Z-axis rotation. It is a figure which shows the measurement error of a related torque sensor. It is a figure which shows the arrangement | positioning relationship between a detection head and a scale at the time of a deformation | transformation of a torque sensor.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment. Further, in order to clarify the explanation, the following description and the drawings are simplified as appropriate, and overlapping explanation is omitted. By the way, in the following explanation, the vocabulary “abbreviation” is used for explanation, but the “abbreviation” does not mean parallelism or constraint in a precise sense, but achieves the object of the present invention. It is used in the meaning including the parallelism and the constraints allowed in the range where

<Embodiment 1>
A torque sensor according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a front view schematically showing a torque sensor. FIG. 2 is a left side view schematically showing the torque sensor. FIG. 3 is a plan view schematically showing the torque sensor.

  The torque sensor 1 is a linear encoder type torque sensor and can be suitably used for, for example, a joint of a robot. The torque sensor 1 includes a first member 11, a second member 12, a connecting member 13, a scale 14, a detection head 15, a first connecting portion 16, and a second connecting portion 17.

  The first member 11 is connected to an input shaft of a robot arm, for example. The first member 11 of the present embodiment is a circular plate member. The first member 11 is disposed substantially parallel to a plane including the X axis and the Y axis.

  The second member 12 is connected to an output shaft such as a reduction gear mounted on the joint of the robot, for example. The 2nd member 12 of this embodiment is made into the shape equivalent to the 1st member 11, and is a circular plate-shaped member. The second member 12 is also disposed substantially parallel to a plane including the X axis and the Y axis. The second member 12 is overlapped with the first member 11 when viewed from the Z-axis direction.

  However, the 1st member 11 and the 2nd member 12 should just be a shape, a material, etc. which can transmit torque favorably from the output shaft, such as a reduction gear, to the input shaft of an arm.

  The connecting member 13 connects the first member 11 and the second member 12. Specifically, the connecting member 13 connects the center of the first member 11 and the center of the second member 12. The connecting member 13 is preferably made of a material and a shape that is twisted about the central axis O and does not substantially bend. When the connecting member 13 is twisted, the first member 11 and the second member 12 rotate relatively around the connecting member 13.

  The scale 14 is provided on the first member 11 via the base 18. Specifically, the scale 14 is provided on the surface of the first member 11 that faces the second member 12. The scale 14 is disposed in the vicinity of the outer peripheral edge of the second member 12.

  The scale 14 has a track (not shown) in the longitudinal direction, similar to a scale used in a general linear encoder. The surface on which the track of the scale 14 is shown is disposed substantially parallel to a plane including the X axis and the Y axis. The surface of the scale 14 on which the track is shown is disposed so as to face the second member 12. The scale 14 is connected to the first line L1 extending in the longitudinal direction of the scale 14 on the plane including the X axis and the Y axis, and the first line L1 and the central axis O of the connecting member 13. It arrange | positions so that 2 line | wire L2 may cross substantially orthogonally. As a result, the longitudinal direction of the scale 14 is arranged in the X-axis direction.

  The detection head 15 is provided on the second member 12 via the base 19. Specifically, the detection head 15 is provided on the surface of the second member 12 that faces the first member 11. At this time, when the first member 11 and the second member 12 rotate relative to each other about the connecting member 13, the detection head 15 has a substantially constant distance from the surface on which the track of the scale 14 is shown. It is arranged so that. The detection head 15 is arranged so as to overlap the scale 14 in the Z-axis direction, that is, to face the surface on which the track of the scale 14 is shown. Therefore, the detection head 15 is disposed in the vicinity of the outer peripheral edge of the first member 11.

  The detection head 15 includes a light emitting source, a light receiving element, and the like, similar to a detection head used for a general linear encoder. That is, when the detection head 15 and the scale 14 are relatively displaced, the detection head 15 detects the relative displacement amount as position information from the number of pulses based on the track indicated on the scale 14. The detection head 15 outputs the position information to a processing device not shown. The processing device calculates a torque acting between the input side and the output side based on the position information, the elastic coefficient of the connecting member 13, and the like.

  Therefore, the detection head 15 moves on the scale 14 when the first member 11 and the second member 12 rotate relatively around the connecting member 13. However, since the relative distance and parallelism between the detection head 15 and the scale 14 change as shown in FIG. 14 or the detection head rotates about the connecting member 13 with respect to the scale as shown in FIG. The relative rotational displacement amount between the first member 11 and the second member 12 cannot be accurately measured (FIG. 15).

Therefore, the torque sensor 1 of the present embodiment includes a first connecting portion 16 and a second connecting portion 17.
The first connecting portion 16 allows displacement of the scale 14 with respect to the detection head 15 in a direction substantially parallel to the first line L1, and the other direction of the scale 14 with respect to the detection head 15 (with the first line L1). The displacement in the direction other than the parallel direction is substantially restrained. Here, generally, the plate-like member has lower rigidity in the direction orthogonal to the widest surface than the rigidity in the other direction.

  Therefore, in the present embodiment, a plate-like member such as a steel material is used as the first connecting portion 16. The widest surface 16a of the first connecting portion 16 is disposed substantially parallel to a plane including the first line L1 and the line L3 that is the central axis O of the connecting member 13. That is, in the illustrated example, the widest surface 16a of the first connecting portion 16 is disposed substantially parallel to a plane including the Y axis and the Z axis. And the 1st connection part 16 is arrange | positioned so that the scale 14 may be inserted | pinched from the longitudinal direction of the said scale 14. FIG. That is, the first connecting portion 16 is disposed so as to face each other in the X-axis direction with the scale 14 interposed therebetween.

  In addition, one portion in the Z-axis direction of the surface of the first connecting portion 16 that faces the other first connecting portion 16 (the portion on the upper side with respect to the paper surface in FIG. 1) is joined to the detection head 15. ing. On the other hand, the other portion of the first connecting portion 16 facing the other first connecting portion 16 in the Z-axis direction (the lower portion relative to the paper surface in FIG. 1) is joined to the scale 14. ing. However, in this embodiment, it is joined to the scale 14 via the base 18. As a result, the first connecting portion 16 connects the scale 14 and the detection head 15.

  Such a first connecting portion 16 allows displacement of the scale 14 with respect to the detection head 15 in a direction substantially parallel to the first line L1 as described above, and the other direction of the scale 14 with respect to the detection head 15. What is necessary is just to set a material, each dimension, etc. so that the displacement to may be substantially restrained. Since the rigidity in each direction can be estimated by using a theoretical formula or a finite element method analysis, it is possible to design in consideration of the degree of reduction in torque detection sensitivity by considering it together with the torsional rigidity of the elastic member 13. . Further, the thickness, width, length, and the like of the member of the first connecting portion 16 can be used as design parameters.

  Here, since the amount of rotational displacement due to the torsion of the elastic member 13 is small, if the rigidity of the first connecting portion 16 in the longitudinal direction of the scale 14 is low, the rigidity of the micro twisting around the central axis O by the first connecting portion 16 is small. Therefore, the influence of the torsional rigidity of the elastic member 13 on the torque measurement is so small that it does not affect the torque measurement (the rigidity of the first connecting part 16 in the X-axis direction is K, the radius from the central axis O is r, the central axis If the equivalent torsional stiffness around O is G, it can be approximated as G = d \ tau / d \ theta = K r ^ 2 d \ theta / d \ theta = K r ^ 2, so if K is low, G will be low ).

  Note that lowering G and K is a trade-off with rigidity in other directions, but the first connecting portion 16 is made sufficiently thin with respect to the width to reduce the length (head surface and scale surface). By shortening the distance direction, the anisotropy of the rigidity can be increased (the rigidity in the longitudinal direction of the scale is low and the rigidity in the other directions is high).

  The second connecting portion 17 substantially restrains displacement of the scale 14 in a direction substantially parallel to the first line L1 on a plane substantially parallel to the plane including the X axis and the Y axis, and moves in the other direction. Allow displacement. Here, in general, a sheet-like elastic body such as rubber has high rigidity in a direction substantially parallel to the plane, while it has low rigidity in other directions. Considering the shape of the scale 14, the rubber sheet takes a long shape in the X-axis direction, and its rigidity is selectively increased in the X-axis direction.

  Therefore, in the present embodiment, a sheet-like elastic body is used as the second connecting portion 17. The second connecting portion 17 is interposed between the base 18 and the first member 11. As a result, the second connecting portion 17 connects the first member 11 and the scale 14.

  Such a second connecting portion 17 is substantially restrained from displacement in a direction substantially parallel to the first line L1 of the scale 14 and is allowed to displace in other directions. What is necessary is just to set a dimension.

FIG. 4 is a front view schematically showing the state of the torque sensor 1 when the first member 11 and the second member 12 are relatively rotated around the connecting member 13.
As described above, the first connecting portion 16 allows the displacement of the scale 14 with respect to the detection head 15 in the direction substantially parallel to the first line L1, and the scale 14 with respect to the detection head 15 in the other direction. The displacement is substantially restrained. Moreover, the second connecting portion 17 substantially restrains the displacement of the scale 14 in the direction substantially parallel to the first line L1 and allows the displacement in other directions. That is, the second connecting portion 17 is substantially prevented from being pulled by the first connecting portion 16 so that the scale 14 follows the direction substantially parallel to the first line L1, and the first member 11 and the second member Even if a relative displacement other than the rotation around the Z axis occurs between the member 12 and the member 12, the relative distance and parallelism between the detection head 15 and the scale 14 are prevented from changing. Further, the second connecting portion 17 slightly moves the scale 14 outward on the second line L2 so as to follow the rotation of the detection head 15 that is displaced along the circumference around the rotation shaft 13. Rotate at the selected position. Since the rigidity of the second connecting portion 17 in the direction other than the first line L1 is lower than the rigidity of the first connecting portion 16, torque measurement is performed between the first member 11 and the second member 12. A displacement in a direction other than the first line L <b> 1 between the scale 14 and the first member 11 can be absorbed without generating an excessive force that prevents it.

  Therefore, the detection head 15 can be accurately displaced along the longitudinal direction of the scale 14 with the relative distance and parallelism between the scale 14 and the detection head 15 being substantially maintained. Therefore, the relative displacement amount between the scale 14 and the detection head 15 can be calculated with high accuracy, and the torque acting on the output side (for example, the arm of the robot) can be calculated with high accuracy.

  Incidentally, the elastic deformation of the second connecting portion 17 causes the scale 14 to be pulled in the direction substantially parallel to the first line L1 by being pulled by the first connecting portion 16, but the second connecting portion 17 The elastic deformation is very small, and the elastic deformation is extremely small compared to the amount of displacement of the scale 14 with respect to the detection head 15 in the direction substantially parallel to the first line L1, and therefore does not substantially affect the measurement accuracy.

  The relative distance between the scale 14 and the detection head 15 when the first member 11 and the second member 12 rotate relative to each other about the connecting member 13 and the first connecting portion 16 tilts. However, the amount of displacement is very small and does not substantially affect the measurement accuracy.

<Embodiment 2>
A torque sensor according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a front view schematically showing the torque sensor. FIG. 6 is a left side view schematically showing the torque sensor. FIG. 7 is a bottom view schematically showing the torque sensor. In addition, the same code | symbol is attached | subjected to the element common to the torque sensor of Embodiment 1. FIG.

The torque sensor 10 according to the present embodiment has substantially the same configuration as the torque sensor 1 according to the first embodiment, but the configuration of the second connecting portion 27 is different.
That is, the second connecting portion 27 includes the pin 21 and the movable portion 22. The pin 21 protrudes from the lower surface of the base 18 in the Z-axis direction. The pin 21 is inserted into the movable part 22.

  The movable portion 22 is formed on the first member 11. The movable part 22 is a notch part formed in a direction parallel to the Y axis. However, the movable part 22 does not need to be a notch shape, and may be a groove or a long hole.

FIG. 8 is a front view schematically showing a state of the torque sensor 10 when the first member 11 and the second member 12 are relatively rotated around the connecting member 13.
When the first member 11 and the second member 12 rotate relative to each other about the connecting member 13, the pin 21 rotates outward in the movable portion 22 while the pin 21 moves outward in the movable portion 22. Thus, the scale 14 can be rotated at a position slightly moved outward on the second line L2 so as to follow the rotation of the detection head 15 that is displaced along the circumference around the connecting member 13. it can. Therefore, similarly to the torque sensor 1 of the first embodiment, the detection head 15 can be accurately displaced along the longitudinal direction of the scale 14. Therefore, the relative displacement amount between the scale 14 and the detection head 15 can be calculated with high accuracy, and the torque acting on the output side (for example, the arm of the robot) can be calculated with high accuracy.

  Note that, as in the illustrated example of the present embodiment, it is preferable that the movable portion 22 has a margin in the X-axis direction, and an elastic member 23 such as a spring is provided between the pin 21 and the movable portion 22. Thereby, the pin 21 can be smoothly operated in the movable portion 22. In addition, since the displacement of the pin 21 in the direction substantially parallel to the first line L1 is substantially restrained by the elastic member 23, the relative displacement between the scale 14 and the detection head 15 is calculated without reducing accuracy. be able to.

  At this time, the elastic modulus in the first line L1 direction of the elastic member 23 is higher than the elastic modulus in the circumferential direction of the first connecting portion 16, and the elastic modulus in the other directions is the elastic modulus of the first connecting portion 16. Set lower.

<Other forms>
The configuration of the second connecting portion is not limited to the above, and as shown in FIGS. 9 and 10, for example, a plane including a portion substantially parallel to the plane including the X axis and the Y axis, and the X axis and the Z axis. The scale 14 and the first member 11 may be connected by plate-like members (sheet metal-like elastic bodies) 37 that are bent so that the substantially parallel portions are alternately continued. In short, it is only necessary that the second connecting portion substantially restrains the displacement in the direction substantially parallel to the longitudinal direction of the scale 14 and allows the displacement in the other direction of the scale 14.

  Further, the arrangement of the scale 14 and the detection head 15 is not limited to the above, and may be arranged as shown in FIGS. 11 and 12, for example. The torque sensor shown in FIG. 11 has substantially the same configuration as that of the torque sensor 1 of the first embodiment, but the surface on which the track of the scale 14 is shown is arranged substantially parallel to a plane including the X axis and the Z axis. Has been. The surface on which the track of the scale 14 is shown is arranged outward. The longitudinal direction of the scale 14 is arranged in the X-axis direction. The scale 14 is connected to the first member 11 via the second connecting portion 47.

  The second connecting portion 47 includes a jig 48 having a L-shaped Y / Z cross section and a sheet-like elastic body 49. The elastic body 49 substantially restrains the displacement of the scale 14 in the longitudinal direction of the scale 14 relative to the first member 11 and allows the displacement in the other direction.

  Further, the detection head 15 is arranged so as to overlap the scale 14 when viewed from the Y-axis direction, that is, to face the surface on which the track of the scale 14 is shown. The detection head 15 is disposed outward from the scale 14 in the Y-axis direction, and is connected to the second member 12 via a jig 41 having an L-shaped Y / Z cross section. However, the surface on which the track of the scale 14 is shown may be disposed inward, and the detection head 15 may be disposed inward with respect to the scale 14 so as to face the track of the scale 14.

  The scale 14 and the detection head 15 are connected via a first connecting portion 46. As the 1st connection part 46, a plate-shaped member is used similarly to the above-mentioned embodiment. The widest surface of the first connecting portion 46 is disposed substantially parallel to a plane including the Y axis and the Z axis. And the 1st connection part 46 is arrange | positioned so that the scale 14 may be inserted | pinched from the longitudinal direction of the said scale 14. FIG.

  Even in such a configuration, the first connecting portion 46 is substantially constrained to allow displacement only in the longitudinal direction of the scale 14, and the longitudinal direction of the scale 14 between the scale 14 and the first member 11. The relative displacement in the direction other than is excessively increased in a direction other than the longitudinal direction of the scale 14 between the scale 14 and the first member 11 due to elastic deformation of the elastic body 49 of the second connecting portion 47 in each direction. It is absorbed without generating a strong force. At this time, when the first member 11 and the second member 12 rotate relatively around the connecting member 13 and the first connecting portion 46 tilts, the relative relationship between the scale 14 and the detection head 15 is reached. Although the distance is displaced, the amount of displacement is minute and does not substantially affect the measurement accuracy. The parallelism between the scale 14 and the detection head 15 is substantially maintained by the elastic deformation of the elastic body 49 of the second connecting portion 47.

  Therefore, the torque sensor shown in FIG. 11 can also accurately displace the detection head 15 along the longitudinal direction of the scale 14 while maintaining the relative distance and parallelism between the scale 14 and the detection head 15 substantially. Therefore, the relative displacement amount between the scale 14 and the detection head 15 can be calculated with high accuracy, and the torque acting on the output side (for example, the arm of the robot) can be calculated with high accuracy.

  The torque sensor shown in FIG. 12 has substantially the same configuration as the torque sensor shown in FIG. 11, but, like the torque sensor shown in FIG. 9, a plate-like member (second connecting portion) in which the scale 14 is bent. It is connected to the first member 11 via 57. In other words, the first member 11 includes portions that are substantially parallel to a plane including the X axis and the Y axis, and portions that are approximately parallel to a plane including the X axis and the Z axis are alternately continuous. A surface of the scale 14 opposite to the surface on which the track is shown is joined to the outer surface of a portion substantially parallel to the plane including the Z axis.

  Even in such a configuration, the first connecting portion 46 is substantially constrained to allow displacement only in the longitudinal direction of the scale 14, and the longitudinal direction of the scale 14 between the scale 14 and the first member 11. Relative displacement in other directions generates an excessive force in a direction other than the longitudinal direction of the scale 14 between the scale 14 and the first member 11 due to elastic deformation of the second connecting portion 57 in each direction. Without being absorbed. At this time, when the first member 11 and the second member 12 rotate relatively around the connecting member 13 and the first connecting portion 46 tilts, the relative relationship between the scale 14 and the detection head 15 is reached. Although the distance is displaced, the amount of displacement is minute and does not substantially affect the measurement accuracy. Further, the parallelism between the scale 14 and the detection head 15 is substantially maintained by the elastic deformation of the second connecting portion 57.

  Accordingly, the torque sensor shown in FIG. 12 can also accurately displace the detection head 15 along the longitudinal direction of the scale 14 while maintaining the relative distance and parallelism between the scale 14 and the detection head 15. Therefore, the relative displacement amount between the scale 14 and the detection head 15 can be calculated with high accuracy, and the torque acting on the output side (for example, the arm of the robot) can be calculated with high accuracy.

As mentioned above, although embodiment of the torque sensor which concerns on this invention was described, it can change in the range which does not deviate not only from said structure but the technical idea of this invention.
For example, in the above-described embodiment, the first member is provided with the scale, and the second member is provided with the detection head. However, the reverse configuration may be used. Moreover, in the above-mentioned embodiment, although the 2nd connection part is arrange | positioned at the scale side, you may arrange | position at the detection head side.

1, 10 Torque sensor 11 First member 12 Second member 13 Connecting member 14 Scale 15 Detection head 16 First connecting portion 16a Widest surface 17, 27, 37 Second connecting portion 18, 19 Base 21 Pin 22 Movable part 23 Elastic member 41 Jig 46 First connecting part 47 Second connecting part 48 Jig 49 Elastic body 57 Second connecting part 100 Torque sensor 110 First rotating plate 120 Second rotating plate 130 Shaft 140 Scale 150 Detection head

Claims (7)

A linear encoder type torque sensor,
A first member;
A second member disposed to face the first member and in a relative rotational relationship with the first member;
A connecting member that connects the first member and the second member;
A plurality of tracks are shown, and the first line extending in the direction in which the tracks extend and the second line connecting the first line and the central axis of the connecting member are orthogonal to each other. A scale provided on one member;
A detection head provided on the second member for detecting position information from the scale;
Connecting the scale and the detection head, allowing displacement of the detection head relative to the scale in a direction parallel to the first line, and parallel to the first line of the detection head relative to the scale A first connecting portion that restrains displacement in a direction other than
The first member and the scale, or the second member and the detection head are connected to each other, the scale relative to the first member, or the first line of the detection head relative to the second member; A second that restrains displacement in a parallel direction and allows displacement in a direction other than the direction parallel to the first line of the scale relative to the first member or the detection member relative to the second member; A connecting portion of
A torque sensor comprising: The first connecting portion includes a plate-like member,
2. The torque sensor according to claim 1, wherein the surface having the largest area of the plate-like member is arranged in parallel to a surface including the second line and a third line that is a central axis of the connecting member. .   The second connecting portion has a rigidity in a direction parallel to the first line higher than that of the first connecting portion, and a rigidity in a direction other than the direction parallel to the first line is the first connecting portion. The torque sensor according to claim 1, wherein the torque sensor is lower than the rigidity of the one connecting portion.   4. The torque sensor according to claim 1, wherein the second connecting portion includes a sheet-like elastic member.   The torque sensor according to claim 1, wherein the second connecting portion includes a sheet metal elastic member. The second connecting portion includes a pin provided on the scale or the detection head,
A movable part in which the pin is inserted and extends in parallel with the second line in the first member or the second member;
The torque sensor according to any one of claims 1 to 3, further comprising:   The torque sensor according to claim 6, wherein the second connection portion includes an elastic member disposed in parallel with the first line between the pin and the movable portion.

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