JP4877665B2 - 3-axis force sensor - Google Patents

Description

  The present invention relates to a triaxial force sensor that can measure forces in three axial directions.

  Conventionally, force sensors have been developed that measure multiaxial forces using strain gauges. For example, in Patent Document 1 below, a disc-shaped strain generating portion, four leg-shaped strain generating portions extended to the disc-shaped strain generating portion, and a strain-receiving portion are attached. A sensor that includes a strain gauge provided and can detect a force in a three-dimensional direction is disclosed.

Further, in Patent Document 2 below, there is a sensor that has four legs extending radially from the central portion and can detect a force in a three-dimensional direction by attaching strain gauges to the legs. It is disclosed.
Japanese Unexamined Patent Publication No. 2004-245717 (first page, FIG. 1 etc.) JP-A-10-78360 (first page, FIG. 1 etc.)

  In the case of the sensor disclosed in Patent Document 1, it is difficult to increase the processing accuracy, and the accuracy of the sensor is lowered. More specifically, it is difficult to configure the disc-shaped strain generating portion in parallel to the surface on which the sensor is installed. If the disk-shaped strain generating part is not configured parallel to the surface on which the sensor is installed, the force applied to the disk-shaped strain generating part cannot be accurately measured by the strain gauge. As a result, the accuracy of the sensor is reduced.

  In general, a force sensor or the like is calibrated after manufacturing and calibrated by the verification. In the case of the sensor disclosed in Patent Document 1 above, a member for applying a force to the disk-shaped strained portion with an adhesive or the like in order to apply a force to the disk-shaped strained portion at the time of verification Will be attached. Then, when the force applied at the time of verification is small, it may be sufficient, but when the force applied at the time of verification increases, the member easily peels off from the disk-shaped strained portion, and appropriate verification cannot be performed. In particular, if the member for applying force is not completely peeled off, but only about half of it is peeled off, an unexpected moment will be applied to the disk-shaped strained part, so accurate verification Will not be able to. If proper verification is not possible, the accuracy of the sensor will be low.

  In the case of the sensor disclosed in Patent Document 2, a strain gauge is attached to each surface of the four columnar legs extending radially from the central portion in order to detect a force in a three-dimensional direction. It is installed. As a result, the legs cannot be thinned, and there is a limit to downsizing the sensor.

The present invention has been made to solve the above-described problems, and one of its purposes is to provide a highly accurate force sensor.
Another object is to provide a force sensor that can perform an appropriate test.
Another object is to provide a force sensor that can be miniaturized.

  In order to achieve the above object, a force sensor according to the present invention includes a central portion to which a force to be measured is applied, four leg portions extending from the central portion outward at a substantially equal angle, and the four pieces. A frame portion joined to each outer end portion of the leg portion, and a plurality of first strain gauges attached to the side surface of the leg portion so as to detect a change in the longitudinal direction of the leg portion; And a plurality of second strain gauges attached to the side surfaces of the leg portions so as to detect a change in a direction having a predetermined acute angle with respect to the longitudinal direction of the leg portions.

  With such a configuration, it is possible to increase the processing accuracy of the member constituted by the center portion, the leg portion, and the frame portion, and as a result, the accuracy of the sensor can be improved. Further, by providing the first strain gauge and the second strain gauge for detecting the force in the triaxial direction on the side surface of the leg portion, the width of the horizontal surface of the leg portion can be reduced, and the triaxial force sense. The sensor can be downsized.

In the triaxial force sensor according to the present invention, the predetermined acute angle may be approximately 45 degrees.
With such a configuration, the shear strain generated in the leg can be detected most effectively by the second strain gauge, and as a result, the accuracy of the triaxial force sensor can be improved.

  In the three-axis force sensor according to the present invention, the first strain gauge is attached to each side surface of the four leg portions, and the second strain gauge is provided on each side surface of the four leg portions. May be respectively installed.

  With such a configuration, eight first strain gauges attached to both side surfaces of the four leg portions and eight second strain gauges attached to both side surfaces of the four leg portions. Are used to detect the force in the three-axis direction, and highly accurate detection can be performed.

In the three-axis force sensor according to the present invention, the two second strain gauges attached to the same leg portion detect changes in the same direction, and are attached to the adjacent leg portions. The provided second strain gauges may detect changes in different directions.
With such a configuration, the wiring of the bridge circuit formed by the second strain gauge can be simplified.

In the triaxial force sensor according to the present invention, the second strain gauge may be located outside the first strain gauge.
With such a configuration, it is possible to more appropriately detect a change by the second strain gauge. Here, the fact that the second strain gauge is outside the first strain gauge refers to the strain gauge attached to one leg.

  Further, in the three-axis force sensor according to the present invention, the four pairs of the first strain gauges attached to the pair of opposing leg parts are paired with the pair of the leg parts attached to the same leg part. The bridge circuit may be formed so that the first strain gauges face each other.

  With such a configuration, a uniaxial force in a plane formed by four legs can be measured by the bridge circuit. Further, by providing two such bridge circuits, the biaxial forces in the plane can be measured respectively.

In the triaxial force sensor according to the present invention, the second strain gauges attached to the same leg part are connected in series, and a pair of the second strain gauges attached to the adjacent leg parts. The bridge circuit may be formed so that the strain gauges are adjacent to each other.
With such a configuration, a force in a direction perpendicular to the plane formed by the four legs can be measured by the bridge circuit.

In the triaxial force sensor according to the present invention, the central portion may have a mechanism to which a member for applying a force can be attached.
With such a configuration, by using the mechanism, an appropriate force can be applied to the central portion, and an appropriate test can be performed. As a result, the accuracy of the three-axis force sensor can be improved.

In the triaxial force sensor according to the present invention, the mechanism may be a threaded hole provided in the central portion.
With such a configuration, the mechanism can be created with a simple configuration.

  According to the force sensor of the present invention, the width of the horizontal surface of the leg is reduced by providing the first strain gauge and the second strain gauge for detecting the force in the three axial directions on the side surface of the leg. Therefore, the three-axis force sensor can be downsized.

  Hereinafter, a triaxial force sensor according to the present invention will be described with reference to embodiments. Note that, in the following embodiments, the components given the same reference numerals are the same or equivalent, and repetitive description may be omitted.

(Embodiment 1)
A three-axis force sensor according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a triaxial force sensor 1 according to the present embodiment. In FIG. 1, a triaxial force sensor 1 according to the present embodiment includes a central portion 11 to which a force to be measured is applied, and four leg portions 12 to 12 extending from the central portion 11 outward at substantially equal angles. 15, the frame portion 16 joined to each of the outer ends of the four leg portions 12 to 15, and the side surfaces of the leg portions 12 to 15 so as to detect changes in the longitudinal direction of the leg portions 12 to 15. The side surfaces of the leg portions 12 to 15 so as to detect the change in the direction having a predetermined acute angle with respect to the longitudinal direction of the leg portions 12 to 15 and the eight first strain gauges 21 to 28 attached to the leg portions 12 to 15. And eight second strain gauges 31 to 38 attached to the. In FIG. 1, the first strain gauges 22, 23, 25, and 28 are attached to the back surfaces of the first strain gauges 21, 24, 26, and 27, respectively, and are not shown. The second strain gauges 32, 33, 35, and 38 are respectively attached to the back surfaces of the second strain gauges 31, 34, 36, and 37, and are not shown.

  2A is a top view of the triaxial force sensor 1, and FIG. 2B is a side view of the triaxial force sensor 1. FIG. In FIG. 2, the first strain gauge and the second strain gauge are not shown. As shown in FIG. 2A, in the triaxial force sensor 1 according to the present embodiment, the legs 12 to 15 are equiangular from the center 11 toward the frame 16, that is, 90 degrees. It is provided for each. The length of each leg part 12-15 shall be equal. In addition, as shown in FIG. 2, it is assumed that the X axis, the Y axis, and the Z axis are set. Note that the size of the three-axis force sensor 1 shown in FIG. 2 is an example, and needless to say, the size may not be the size shown in FIG.

  The center portion 11 is formed in a columnar shape, and has a tap hole 17 that is a mechanism to which a member for applying a force to the triaxial force sensor 1 can be attached at the center. The tapped hole 17 is a threaded hole (female screw). The tap hole 17 may be provided from the upper surface of the center portion 11 to a predetermined depth, or may penetrate through the back surface side. The member for applying a force to the triaxial force sensor 1 is, for example, a member having a male screw that is screwed into the tap hole 17. Instead of the tap hole 17, the central portion 11 may have another mechanism to which a member for applying a force to the triaxial force sensor 1 can be attached. For example, the mechanism may be a cylindrical or prismatic hole provided in the central portion 11, may be a male screw provided in the central portion 11, or may be another mechanism. Good.

  As described above, the first strain gauges 21 to 28 and the second strain gauges 31 to 38 are attached to the leg portions 12 to 15. The first strain gauges 21 to 28 and the second strain gauges 31 to 38 are attached to the leg portions 12 to 15 by being bonded to the leg portions 12 to 15, for example. As can be seen from FIGS. 1 and 2, the width of the side surfaces of the leg portions 12 to 15 is sufficiently larger than the width of the horizontal plane. Here, the width of the side surface is a width in a direction perpendicular to the longitudinal direction of the leg portions 12 to 15. Moreover, the width of the horizontal plane is a width in a direction perpendicular to the longitudinal direction of the leg portions 12 to 15. The longitudinal direction of the leg portions 12 to 15 is a direction connecting the center portion 11 side and the frame portion 16 side of the leg portions 12 to 15. The horizontal plane of the leg portions 12 to 15 is a plane formed by the four leg portions 12 to 15.

  The 1st strain gauge 21 and the 2nd strain gauge 31 which were attached to the one side surface of the leg part 12 are demonstrated using FIG. As shown in FIG. 3, the first strain gauge 21 is attached to the side closer to the central portion 11 so that a change in the longitudinal direction of the leg portion 12 can be detected. The second strain gauge 31 is attached to the side close to the frame portion 16 so as to detect a change in a direction having a predetermined acute angle with respect to the longitudinal direction of the leg portion 12. Here, in the present embodiment, the predetermined acute angle is approximately 45 degrees. That is, the second strain gauge 31 can detect a change (shear strain) in the direction of 45 degrees from the direction of the leg portion 12 from the frame portion 16 side to the center portion 11 side. The predetermined acute angle may be any angle as long as it is greater than 0 degrees and less than 90 degrees, but the force can be measured most effectively at 45 degrees. In addition, detecting a change means detecting a change in length. The positional relationship between the side surfaces of the leg portions 12 of the first strain gauge 21 and the second strain gauge 31 is the same for the other side surfaces of the leg portions 12 to 15 other than the direction of the second strain gauge.

  On the other side of the leg 12, that is, on the back side of the side shown in FIG. 3, as shown in FIG. 4, the first strain gauge 22 is attached on the side close to the center 11, A second strain gauge 32 is attached on the side close to the frame portion 16. The direction of the first strain gauge 22 and the direction of the second strain gauge 32 are the same as the direction of the opposite side surface (the side surface shown in FIG. 3). In order to improve the measurement accuracy, the position where the first strain gauge 21 is attached and the position where the first strain gauge 22 is attached are the same on both side surfaces of the leg 12. It is preferable that Similarly, the position and angle at which the second strain gauge 31 is attached and the position and angle at which the second strain gauge 32 are attached may be the same on both side surfaces of the leg portion 12. preferable. As can be seen from FIGS. 3 and 4, in the present embodiment, the two second strain gauges 31 and 32 attached to the same leg 12 detect changes in the same direction, respectively. To do. The same applies to the two second strain gauges attached to the other legs 13 to 15.

  FIG. 5 is a view for explaining the first strain gauge 23 and the second strain gauge 33 attached to one side surface of the leg portion 13. As shown in FIG. 5, in the leg portion 13, the second strain gauge 33 can detect a change in the direction from the center portion 11 side of the leg portion 12 to the frame portion 16 side and a direction that forms 45 degrees. It is installed so that it can. The same applies to the other side surface of the leg portion 13, that is, the back surface side of the side surface shown in FIG. In this way, the second strain gauges 31 and 32 attached to the leg portion 12 and the second strain gauges 33 and 34 attached to the leg portion 13 detect changes in different directions. become. The same applies to the second strain gauges attached to the other legs. That is, in the present embodiment, the second strain gauges attached to the adjacent legs detect changes in different directions.

  Thus, in this Embodiment, the change which arises in the leg parts 12-15 is detected by the 1st strain gauges 21-28 and the 2nd strain gauges 31-38. That is, the leg portions 12 to 15 are strain generating portions.

  In addition, with respect to the leg portion 12 and the leg portion 14, it is preferable that the first strain gauge 21 and the first strain gauge 26 are attached at positions that are symmetric with respect to the central axis of the central portion 11. is there. The same applies to the first strain gauge 22 and the first strain gauge 25, the second strain gauge 31 and the second strain gauge 36, and the second strain gauge 32 and the second strain gauge 35. . The same applies to the first strain gauge and the second strain gauge attached to the leg portion 13 and the leg portion 15.

  Next, a bridge circuit formed by the first strain gauges 21 to 28 will be described. First, the four first strain gauges 21, 22, 25, 26 attached to the pair of opposing leg portions 12, 14 will be described. As shown in FIG. 6, the first strain gauges 21, 22, 25, 26 are formed with a bridge circuit so that a pair of first strain gauges attached to the same leg portion face each other. . More specifically, as shown in FIG. 6, the pair of first strain gauges 21 and 22 attached to the same leg portion 12 exist at positions facing each other in the bridge circuit. Similarly, a pair of first strain gauges 25 and 26 attached to the same leg portion 14 also exist at positions facing each other in the bridge circuit.

  A bridge circuit formed by the four first strain gauges 23, 24, 27, 28 attached to the pair of opposing leg portions 13, 15 will be described. As shown in FIG. 7, the four first strain gauges 23, 24, 27, 28 attached to the pair of opposing legs 13, 15 are attached to the same leg. A bridge circuit is formed such that the pair of first strain gauges face each other. More specifically, the pair of first strain gauges 23 and 24 attached to the same leg portion 13 exist at positions facing each other in the bridge circuit as shown in FIG. Similarly, a pair of first strain gauges 27 and 28 attached to the same leg 15 are also present at opposing positions in the bridge circuit.

  Next, a bridge circuit formed by the second strain gauges 31 to 38 will be described with reference to FIG. In FIG. 8, the second strain gauges attached to the same leg are connected in series, and the bridge circuit is connected so that a pair of second strain gauges attached to adjacent legs are adjacent to each other. It is formed. More specifically, the pair of second strain gauges 31 and 32 attached to the same leg portion 12 are connected in series as shown in FIG. The same applies to the pair of second strain gauges 33 and 34 attached to the other leg portions 13 to 15. The pair of second strain gauges 31 and 32 attached to the leg portion 12 and the pair of second strain gauges 33 and 34 attached to the leg portion 13 are bridged so as to be adjacent to each other. A circuit is formed. In other words, the pair of second strain gauges attached to the opposing leg portions exist at opposing positions in the bridge circuit.

  In each bridge circuit illustrated in FIGS. 6 to 8, the input and output are as illustrated. As an input, for example, a DC voltage of about 2 to 3 V is applied. In addition, this voltage value is an example, For example, you may apply the voltage of about 1-10V. In this embodiment, a case where a DC voltage is applied is described, but an AC voltage may be applied. At the output, current or voltage is measured.

  Next, detection of a change in length by each strain gauge when a force is applied to the central portion 11 of the triaxial force sensor 1 according to the present embodiment will be described. First, a case where a force Fz is applied to the central portion 11 in the Z-axis direction will be described with reference to FIG. As shown in FIGS. 9A and 9B, the force Fz is a positive direction of the Z axis. When the force Fz is applied to the central portion 11, the central portion 11 moves in the positive direction of the Z axis, and the leg portions 12 to 15 are bent. As a result, as shown in FIG. 9A, the first strain gauges 21 and 26 and the second strain gauges 31 and 36 detect a change in the direction in which the length increases. Specifically, the resistance values of the first strain gauges 21 and 26 and the second strain gauges 31 and 36 are increased. The same applies to the first strain gauges 22 and 25 and the second strain gauges 32 and 35.

  As shown in FIG. 9B, the first strain gauges 24 and 27 detect a change in the direction in which the length increases. Specifically, the resistance values of the first strain gauges 24 and 27 are increased. The same applies to the first strain gauges 23 and 28. The second strain gauges 34 and 37 detect a change in the direction in which the length contracts. Specifically, the resistance values of the first strain gauges 24 and 27 are reduced. The same applies to the second strain gauges 33 and 38.

  Thus, the change in the length is detected by each strain gauge, so that the change in the Z-axis direction is detected in the bridge circuit formed by the second strain gauges 31 to 38. Specifically, since the bridge circuit is formed as shown in FIG. 8, the change in the resistance value of the second strain gauges 31, 32, 35, 36, that is, the increase in the resistance value, and the second strain gauge. A change in the resistance values of 33, 34, 37, and 38, that is, a decrease in the resistance value changes the output voltage.

  On the other hand, in the bridge circuit formed by the first strain gauges 21, 22, 25, 26, no change in the Z-axis direction is detected. Specifically, since the bridge circuit is formed as shown in FIG. 6, when the change in the resistance value of the first strain gauges 21, 22, 25, 26, that is, the increase in the resistance value is equal, the output is There will be no change in voltage. Similarly, the output voltage of the bridge circuit formed by the first strain gauges 23, 24, 27, and 28 is not changed.

  As described above, in the triaxial force sensor 1 according to the present embodiment, the shear strain generated in the leg portions 12 to 15 as the strain generating portions is detected by the second strain gauges 31 to 38, thereby Can be detected.

  Next, a case where a force Fy is applied to the central portion 11 in the Y-axis direction will be described with reference to FIG. As shown in FIGS. 10A and 10B, the force Fy is the positive direction of the Y axis. When the force Fy is applied to the central portion 11, the central portion 11 moves in the positive direction of the Y axis, the leg portion 12 is compressed, and the leg portion 14 extends. Moreover, the leg parts 13 and 15 will bend. As a result, as shown in FIG. 10A, the first strain gauge 21 and the second strain gauge 31 detect a change in the direction in which the length contracts. Specifically, the resistance values of the first strain gauge 21 and the second strain gauge 31 are reduced. The same applies to the first strain gauge 22 and the second strain gauge 32. On the other hand, the first strain gauge 26 and the second strain gauge 36 detect a change in the direction in which the length increases. Specifically, the resistance values of the first strain gauge 26 and the second strain gauge 36 are increased. The same applies to the first strain gauge 25 and the second strain gauge 35.

  As shown in FIG. 10B, the first strain gauges 24 and 27 and the second strain gauges 34 and 37 detect a change in the direction in which the length increases. Specifically, the resistance values of the first strain gauges 24 and 27 and the second strain gauges 34 and 37 are increased. On the other hand, for the first strain gauges 23 and 28 and the second strain gauges 33 and 38, not shown, a change in the direction in which the length contracts is detected. Specifically, the resistance values of the first strain gauges 23 and 28 and the second strain gauges 33 and 38 are reduced.

  Thus, by detecting a change in length by each strain gauge, a change in the Y-axis direction is detected in the bridge circuit formed by the first strain gauges 21, 22, 25, and 26. . Specifically, since the bridge circuit is formed as shown in FIG. 6, the resistance value of the first strain gauges 25, 26, that is, the increase of the resistance value, and the first strain gauges 21, 22 are changed. A change in resistance value, that is, a decrease in resistance value changes the output voltage.

  On the other hand, in the bridge circuit formed by the first strain gauges 23, 24, 27, and 28, no change in the Y-axis direction is detected. Specifically, since the bridge circuit is formed as shown in FIG. 7, the magnitude of the change in the resistance value of the first strain gauges 23, 28, that is, the decrease in the resistance value, and the first strain gauge 24. , 27, that is, when the respective magnitudes of the increase in resistance value are equal, the output voltage does not change.

  Further, even in the bridge circuit formed by the second strain gauges 31 to 38, no change in the Y-axis direction is detected. More specifically, since the bridge circuit is formed as shown in FIG. 8, the magnitudes of changes in the resistance values of the second strain gauges 31, 32, 33, and 38, that is, decreases in the resistance value, When the resistance values of the strain gauges 34, 35, 36, and 37 are equal to each other, that is, each increase in resistance value is equal, the output voltage does not change.

  As described above, in the triaxial force sensor 1 according to the present embodiment, the force in the Y-axis direction is detected by detecting the compression and tension (longitudinal strain) generated in the leg portions 12 and 14 as the strain generating portions. can do.

  Even when a force is applied to the central portion 11 in the X-axis direction, the force in the X-axis direction is detected by the bridge circuit shown in FIG. 7 in the same manner as when the force Fy is applied in the Y-axis direction. be able to. In this case, the output voltage of the bridge circuit shown in FIGS. 6 and 8 does not change as in the case where the force Fy is applied in the Y-axis direction.

  In the above description, the ideal case has been described. However, in reality, when a force is applied in the Z-axis direction, the output voltage of the bridge circuit shown in FIGS. 6 and 7 may change. When a force is applied in the Y-axis direction, the output voltage of the bridge circuit shown in FIGS. 7 and 8 may change, and when a force is applied in the X-axis direction, it is shown in FIGS. The output voltage of the bridge circuit may change. This can be particularly noticeable when the strain-generating portion is small. When interference occurs in this way, interference correction may be performed. Since the interference correction method is already known, the description thereof is omitted.

  Next, a method for manufacturing the three-axis force sensor 1 according to the present embodiment will be briefly described. The member composed of the center part 11, the leg parts 12 to 15, and the frame part 16 may be created by, for example, an NC lathe, may be created by pressing or punching, or may be created by sintering or the like. Also good. As a material of the member composed of the central portion 11, the leg portions 12 to 15 and the frame portion 16, for example, a steel material such as chromium molybdenum steel (SCM) or a metal having appropriate rigidity such as aluminum or stainless steel may be used. Good. In order to detect a minute force, for example, a soft metal such as aluminum may be used. On the other hand, when it is desired to detect a large force, for example, a hard metal such as chromium molybdenum steel may be used.

  The first strain gauges 21 to 28 and the second strain gauges 31 to 38 are attached to the leg portions 12 to 15 thus formed. This attachment is performed using an adhesive or the like as described above. In this case, for example, as shown in FIG. 11, a strain gauge unit including a first strain gauge and a second strain gauge is configured, and the strain gauge unit is attached to the legs 12 to 15. You may make it install. By accurately setting the angle and position of the first strain gauge and the second strain gauge in this strain gauge unit, the angle and position at which the strain gauge unit is installed when the strain gauge unit is installed. Since it is only necessary to pay attention to this, workability is improved.

  In this manner, after the first strain gauges 21 to 28 and the second strain gauges 31 to 38 are attached to the leg portions 12 to 15, the bridge circuits of FIGS. 6 to 8 are formed. Perform wiring. In the bridge circuit of FIG. 8, since the 2nd strain gauges stuck on the same leg part are connected in series, wiring can be performed more easily.

  As described above, after the triaxial force sensor 1 according to the present embodiment is configured, a predetermined male screw is screwed into the tap hole 17 and the test is performed. Further, if necessary, interference correction may be performed.

  Actually, when the triaxial force sensor 1 according to the present embodiment is used, the frame portion 16 is fixed to a predetermined position with screws or the like. Then, by applying a predetermined input voltage to each bridge circuit and observing the change in output according to the force applied to the central portion 11, the magnitude of the force in the three-axis directions can be known.

As described above, according to the three-axis force sensor 1 according to the present embodiment, when the three-axis force sensor 1 is manufactured, there is no need to perform a process of bending a metal plate or the like like the sensor of Patent Document 1 described above. Therefore, the highly accurate triaxial force sensor 1 can be configured, and as a result, the detection accuracy of the triaxial force sensor 1 is increased.
Moreover, since the tap hole 17 is provided in the center part 11 and the test can be performed using the tap hole 17, an appropriate test can be performed.

  Further, since the force in the Z-axis direction is detected by the shear strain, the force in the Z-axis direction can be detected by the second strain gauges 31 to 38 attached to the side surfaces of the leg portions 12 to 15. Therefore, unlike the sensor of Patent Document 2 described above, it is not necessary to install strain gauges on the horizontal surfaces of the leg portions 12 to 15, and the width of the horizontal surfaces of the leg portions 12 to 15 can be reduced. As a result, the radius of the cylindrical side surface inside the frame portion 16 can be reduced, the triaxial force sensor 1 can be miniaturized, and strain gauges are attached to the side surfaces of the leg portions 12 to 15. Workability is improved.

  In the present embodiment, the first strain gauges 21 to 28 are respectively attached to the side surfaces of the four leg portions 12 to 15, and the second strain is applied to the side surfaces of the four leg portions 12 to 15. Although the case where the gauges 31 to 38 are respectively installed has been described, the number of strain gauges is not limited to this. For example, although the measurement accuracy is lowered, the first strain gauge may be attached only to one side surface of the four legs 12 to 15. Further, the second strain gauge may be attached only to one side surface of the four leg portions 12 to 15.

  In the present embodiment, the case where the second strain gauge is on the outer side with respect to the central portion 11 than the first strain gauge has been described, but it is needless to say that the present invention is not limited to this. For example, the first strain gauge may be located outside the center portion 11 with respect to the second strain gauge 31. However, as a result of experiments by the inventor, it is known that the detection by the second strain gauge can be performed more effectively when the second strain gauge is outside the first strain gauge. For this reason, it is preferable that the second strain gauge is outside the first strain gauge.

  Further, in the present embodiment, a case has been described in which the two second strain gauges attached to the same leg portion detect changes in the same direction, but this need not be the case. For example, two second strain gauges attached to the same leg may detect changes in different directions. In that case, it is necessary to change the configuration of the bridge circuit of FIG. 8, but by using an appropriate bridge circuit, the force in the Z-axis direction is appropriately detected by the second strain gauge as in the present embodiment. can do.

  Further, in the present embodiment, the case where the bridge circuit is formed as illustrated in FIGS. 6 to 8 has been described, but it is needless to say that the bridge circuit is not limited thereto. For example, in FIG. 6, the positions of the first strain gauge 21 and the first strain gauge 22 may be interchanged.

Moreover, it cannot be overemphasized that the shape of the center part 11, the leg parts 12-15, and the frame part 16 is not limited to the thing of this Embodiment. For example, the central portion 11 may be formed in a prismatic shape or a spherical shape. Further, the inner peripheral surface of the frame portion 16 may not be cylindrical, and may be formed in a prismatic shape, for example. Moreover, although this Embodiment demonstrated the case where each length of the leg parts 12-15 was equal, it may not be so. Therefore, the center part 11 does not have to exist at the exact center position of the frame part 16. However, even if the lengths of the leg portions 12 to 15 are not equal, the lengths of the opposing leg portions are preferably equal.
Further, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the triaxial force sensor according to the present embodiment, the force in the triaxial direction can be appropriately detected. For example, in various devices as a sensor for detecting the triaxial force, etc. Useful.

The perspective view which shows the triaxial force sensor by Embodiment 1 of this invention. Top view (a) and side view (b) of triaxial force sensor according to the embodiment The figure for demonstrating the installation to the leg part of the strain gauge in the embodiment The figure for demonstrating the installation to the leg part of the strain gauge in the embodiment The figure for demonstrating the installation to the leg part of the strain gauge in the embodiment The figure which shows an example of the bridge circuit formed with the strain gauge in the embodiment The figure which shows an example of the bridge circuit formed with the strain gauge in the embodiment The figure which shows an example of the bridge circuit formed with the strain gauge in the embodiment The figure for demonstrating the case where the force of a Z-axis direction is applied to the triaxial force sensor by the same embodiment The figure for demonstrating the case where the force of the Y-axis direction is applied to the triaxial force sensor by the same embodiment The figure for demonstrating the installation to the leg part of the strain gauge in the embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3 axis force sensor 11 Center part 12-15 Leg part 16 Frame part 17 Tap hole 21-28 1st strain gauge 31-38 2nd strain gauge

Claims (7)

A center where the force to be measured is applied,
Four legs extending substantially equiangularly outward from the center,
A frame portion joined to each of the outer ends of the four legs,
A plurality of first strain gauges attached to the side of the leg so as to detect a change in the longitudinal direction of the leg;
A plurality of second strain gauges attached to the side of the leg so as to detect a change in a direction having a predetermined acute angle with respect to the longitudinal direction of the leg ,
The first strain gauges are respectively attached to the side surfaces of the four legs,
The second strain gauges are respectively attached to the side surfaces of the four legs,
The two second strain gauges attached to the same leg portion detect changes in the same direction,
The triaxial force sensor , wherein the second strain gauges attached to the adjacent legs detect changes in different directions . A center where the force to be measured is applied,
Four legs extending substantially equiangularly outward from the center,
A frame portion joined to each of the outer ends of the four legs,
A plurality of first strain gauges attached to the side of the leg so as to detect a change in the longitudinal direction of the leg;
A plurality of second strain gauges attached to the side of the leg so as to detect a change in a direction having a predetermined acute angle with respect to the longitudinal direction of the leg,
The first strain gauges are respectively attached to the side surfaces of the four legs,
The second strain gauges are respectively attached to the side surfaces of the four legs,
For the four first strain gauges attached to the pair of opposing leg portions,
A triaxial force sensor in which a bridge circuit is formed so that a pair of the first strain gauges attached to the same leg portion face each other. A center where the force to be measured is applied,
Four legs extending substantially equiangularly outward from the center,
A frame portion joined to each of the outer ends of the four legs,
A plurality of first strain gauges attached to the side of the leg so as to detect a change in the longitudinal direction of the leg;
A plurality of second strain gauges attached to the side of the leg so as to detect a change in a direction having a predetermined acute angle with respect to the longitudinal direction of the leg,
The first strain gauges are respectively attached to the side surfaces of the four legs,
The second strain gauges are respectively attached to the side surfaces of the four legs,
The second strain gauges attached to the same leg are connected in series;
A triaxial force sensor in which a bridge circuit is formed so that a pair of the second strain gauges attached to the adjacent leg portions are adjacent to each other. The triaxial force sensor according to any one of claims 1 to 3, wherein the predetermined acute angle is approximately 45 degrees. The second strain gauge, than said first strain gauge is outside, 3-axis force sensor according to any one of claims 1 to 4. The triaxial force sensor according to any one of claims 1 to 5 , wherein the central portion has a mechanism to which a member for applying a force can be attached. The triaxial force sensor according to claim 6 , wherein the mechanism is a threaded hole provided in the central portion.

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