JP2017058337A - Inner force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sufficient rigidity to the moment of the sensor structure of an inner force sensor.SOLUTION: An inner force sensor according to an embodiment of the invention comprises: a load action part 20 that receives the action of a force; a center shaft part 21 to which the load action part 20 is connected coaxially; at least three or more measurement beam parts 22 radially extending in the radial direction from the center shaft part 21; at least three or more support beam parts 24 arranged on the load action part 20 side, with a space therefrom, in the axial direction of the center shaft part 21, and radially extending in the radial direction from the center shaft part 21; and a connection part 23 for connecting the end of each of the measurement beams 22 and the support beams 24 with each other and sticking fast to the fixing part 19 of the structure, the inner force sensor further having deformation detection sensors 27, 28 for detecting the deformation of the measurement beam 22 due to a force acting on the load action part 20.SELECTED DRAWING: Figure 3

Description

  Embodiments of the present invention relate to a force sensor for measuring, for example, translational forces and moments in a plurality of axial directions acting on a leg or a hand of a robot.

  The performance of manipulators such as industrial robots has been greatly improved, and it has become possible to realize fairly complex motions, and the applications have expanded from simple tasks to tasks that require complex motions. Yes. In order to realize more flexible operations such as grasping, carrying, standing walking, and going up and down stairs for various objects, conventionally, a sense of force is applied to the robot's hand, wrist, or leg. A force sensor is provided.

  Robots equipped with a force sensor include a robot walking with two legs and a multi-legged walking robot having four or more legs. This type of multi-legged walking robot can climb up and down stairs and overcome obstacles by itself. In a multi-legged walking robot, a force sensor is placed at each leg tip to accurately detect the load applied to each leg, calculate the center of gravity, and control the center of gravity so that it will not fall over while walking. ing.

  This type of force sensor is a sensor that detects translational force and moment by converting them into elastic strain. However, the detection accuracy and strength vary depending on the configuration of the sensor structure. In general, in order to increase detection accuracy, the sensor structure is easily bent, but the sensor structure is also required to have rigidity.

  In recent years, force sensors that can measure translational forces and moments in 6-axis directions have been developed. For example, cross-shaped strain-generating arms are arranged in two layers, and the ends of the cross structure are connected to each other. Thus, there is known a force sensor in which the strain-generating arm is easily bent to reduce the size of the sensor structure and to improve the measurement accuracy of the six-axis translational force and moment.

Japanese Patent No. 3459939

  Some robots with built-in force sensors cannot avoid the action of a large moment due to their structure and function. In the case of a multi-legged walking robot, which is a representative example, since the weight of the robot body is supported by the legs, an impact from the floor and a large moment act on each leg during walking. Naturally, a large moment also acts on the force sensor incorporated in each leg.

  In a multi-legged walking robot in which each leg portion is relatively thin in terms of walking function, the moment is excessive for the force sensor, and it may not be able to withstand and may be damaged.

  On the other hand, it is conceivable to use a large sensor that can withstand the moment according to the magnitude of the moment acting during walking, but in this case, the sensor will not fit in the size of a leg of practical thickness. There was a case.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a force sensor capable of ensuring sufficient rigidity against a moment.

In order to achieve the above object, a force sensor according to an embodiment of the present invention measures at least one of three orthogonal forces acting on a manipulator structure and a moment around each axis. A force sensor that receives a force action,
A central shaft portion to which the load acting portion is connected coaxially, at least three or more measurement beam portions extending radially from the central shaft portion in a radial direction, and the load acting portion side in the axial direction of the central shaft portion Fixing the structure by connecting at least three or more support beam portions that are arranged at an interval and extend radially from the central shaft portion, and ends of the measurement beam portion and the support beam portion. And a deformation detecting sensor for detecting deformation of the measurement beam portion due to the force acting on the load acting portion.

  According to the embodiment of the present invention, sufficient rigidity against moment can be secured.

It is a side view showing an outline of a multi-legged walking robot to which a force sensor according to an embodiment of the present invention is applied. It is sectional drawing which shows the force sensor integrated in the leg part of the multilegged walking robot of FIG. It is a perspective view which shows the force sensor by 1st Embodiment of this invention. It is the figure which showed the measurement beam part and the support beam part seeing the force sensor by 2nd Embodiment of this invention from the X-axis direction. It is the figure which showed the measurement beam part and the support beam part seeing the force sensor by 3rd Embodiment of this invention from the X-axis direction. It is the figure which showed the measurement beam part and the support beam part when seeing the force sensor by 4 embodiment of this invention from the X-axis direction. It is the figure which showed the measurement beam part and the support beam part seeing the force sensor by 5th Embodiment of this invention from the X-axis direction. It is the figure which showed the positional relationship of a measurement beam part and a support beam part seeing the force sensor by 6th Embodiment of this invention from a Z-axis direction. It is a perspective view which shows the force sensor by 7th Embodiment of this invention. It is sectional drawing which shows the force sensor by 8th Embodiment integrated in the leg part of the multilegged walking robot of FIG. It is a figure explaining arrangement | positioning of the displacement sensor in the force sensor by 8th Embodiment.

Hereinafter, embodiments of a force sensor according to the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 shows a multi-legged walking robot to which the force sensor according to the present embodiment is applied. This multi-legged walking robot 10 is a robot that walks with four legs. The robot body 12 is supported by legs 14 having a plurality of joints.

  When the leg tip part 15 at the tip of each leg part 14 reaches the floor surface 13 (ground), it receives the reaction force of its own weight as a load. A force sensor 16 is incorporated at the base of each leg portion 15 of the multi-legged walking robot 10. In the walking robot 10, each force sensor 16 accurately detects the translational force and moment applied to each leg tip 15 to calculate the center of gravity position, and controls the center of gravity position so as not to fall during walking. . By such center-of-gravity position control, the multi-legged walking robot 10 is configured not only to walk on a flat ground, but also to climb up and down stairs and get over obstacles by itself.

Next, the structure of the force sensor 16 according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a view showing a longitudinal section of the force sensor 16 incorporated in the distal end portion of the leg portion 14 of the walking robot 10.
As shown in FIG. 2, the distal end portion of the leg portion 14 is a hollow structural member, and a fixing portion 19 for fixing the sensor main body 18 is formed. The sensor body 18 is fixed so as to be fitted into the inner diameter portion of the fixing portion 19.

  A curved surface is formed on the end surface of the leg tip portion 15, and the leg tip portion 15 is landed on the floor surface 13 via the curved surface. The leg tip portion 15 and the sensor body 18 are connected via a coaxial load acting portion 20 having a reduced diameter.

Next, FIG. 3 is a perspective view showing the structure of the sensor body 18 of the force sensor 16.
In the force sensor 16, in order to specify the direction of the force (load) and moment applied from the leg tip portion 15, a three-dimensional coordinate system including the X axis, the Y axis, and the Z axis is set as shown in FIG. Has been. In this case, the Z-axis extends in the length direction of the leg portion 14, and the plane perpendicular to the length direction of the leg portion 14 is the XY plane.

  The sensor body 18 of the force sensor 16 includes a columnar central shaft portion 21 at the center thereof, measurement beam portions 22a to 22d extending radially from one end side of the central shaft portion 21 and having strain measurement surfaces, Support beam portions 24a to 24d extending radially from the other end side of the shaft portion 21, and each of the measurement beam portions 22a to 22d and connection portions 23a to 23d connecting the support beam portions 24a to 24d. ing. As the material of the sensor body 18, for example, aluminum or an aluminum alloy is used.

  In the first embodiment, the central shaft portion 21 has an octagonal prism shape, and from this central shaft portion 21, the measurement beam portions 22a to 22d having the same length are parallel to the XY plane. And are arranged so as to extend equiangularly. Among these, the measurement beam portions 22a and 22c are parallel to the X axis, and the remaining measurement beam portions 22b and 22d are parallel to the Y axis.

  Each of the support beam portions 24a to 24d has the same length as the measurement beam portions 22a to 22d, and is shifted in the Z-axis direction toward the load acting portion 20 so as to be in phase with the support beam portions 24a to 24d. They are arranged to extend equiangularly in a cross in parallel to the Y plane.

  The connecting portions 23a to 23d are arranged in parallel to the Z-axis direction, and connect the measuring beam portions 22a to 22d and the supporting beam portions 24a to 24d.

  The sensor body 18 is provided with a deformation detection sensor that detects deformation of the measurement beam portions 22 a to 22 d due to a load acting via the load action portion 20 at least one of the measurement beam portion 22 and the central shaft portion 21.

  The deformation detection sensor according to the present embodiment is a strain sensor unit as a strain detection unit that detects an elastic strain (deflection) that is a deformation of the measurement beam units 22a to 22d due to a load acting via the load application unit 20. These are arranged in the measurement beam portions 22a to 22d as follows. For example, strain gauges are used in these strain sensor units.

  Each of the measurement beam portions 22a to 22d has a total of four measurement surfaces such as an upper surface and a lower surface (a surface parallel to the XY plane) and left and right side surfaces (a surface parallel to the XZ plane). The upper surface, the lower surface, and the left and right side surfaces form a pair. In the force sensor according to the present embodiment, two paired strain gauges are provided on each of the upper and lower surfaces and the left and right side surfaces.

  In FIG. 3, the measurement surfaces 25a to 25d on the upper surface of the measurement beam portions 22a to 22d and the measurement surfaces 26a to 26d on one side surface are shown, but the lower surface and the other side surface not visible in FIG. The surfaces 25a ′ to 25d ′ and the measurement surfaces 26a ′ to 26d ′ are distinguished by marking “′”. Strain sensor units 27a to 27d are arranged on the measurement surfaces 25a to 25d, and strain sensor units 27'a to 27'd are arranged on the measurement surfaces 25a 'to 25d' on the lower surface.

  Similarly, strain sensor portions 28a to 28d are disposed on the measurement surfaces 26a to 26d on one side surface of each of the measurement beam portions 22a to 22d, and strain sensors are disposed on the measurement surfaces 26a 'to 26d' on the other side surface. Portions 28a 'to 28d' are arranged.

  When a translational force in the (+) X-axis direction is applied to such a sensor body 18 via the load acting portion 20, the measurement surfaces 26b and 26d extend, whereas the opposite measurement surface 26b ′, 26d 'will shrink. When a translational force in the (−) X-axis direction is applied, the measurement surfaces 26b and 26d are contracted, whereas the opposite measurement surfaces 26b ′ and 26d ′ are extended. Therefore, since the voltages of the strain sensor units 28b, 28b ′, 28d, and 28d ′ arranged on these measurement surfaces change in proportion to the magnitude of the force in the X-axis direction, these strain sensor units 28b, 28b ′. , 28d and 28d ′ can be configured as a Wheatstone bridge by a known circuit connection, and the translational force in the X-axis direction can be detected by measuring the voltage.

  Similarly, when the moment about the X-axis acts on the sensor body 18 via the load acting portion 20, the measurement surfaces 25b, 25b ′, 25d, and 25d ′ are deformed, so that the distortions arranged on these measurement surfaces By configuring a Wheatstone bridge with the sensor units 27b, 27b ′, 27d, and 27d ′ and measuring the voltage, a moment around the X axis can be formulated.

なお、Ｚ軸方向の並進力については、歪センサ部２８ｂ、２８ｂ’、２８ｄ、２８ｄ’の組み合わせによっても測定できる、Ｚ軸回りのモーメントにもついても、歪センサ部２７ｂ、２７ｂ’、２７ｄ、２７ｄ’によっても測定できる。測定対象が異なり、歪センサ部の組み合わせが同じ場合はホイートストンブリッジの構成が異なる。すなわち、本実施形態においては、Ｘ軸、Ｙ軸およびＺ軸のそれぞれの方向に対して、２つで一対となる歪ゲージの対が２対ずつ、つまりそれぞれ合計４つの歪ゲージが設けられて、Ｘ軸、Ｙ軸およびＺ軸方向の並進力とこれらの軸周りのモーメントを測定するように構成されている。 Y-axis direction, Z-axis direction translational force, Y-axis direction, and moments around the Z-axis direction can be measured by the same measurement principle, so all the forces and moments in the 6-axis direction are measured in Table 1. The combination of a surface and a strain sensor part is shown.

Note that the translational force in the Z-axis direction can be measured by a combination of the strain sensor units 28b, 28b ′, 28d, and 28d ′, and the moment around the Z axis can be measured with the strain sensor units 27b, 27b ′, 27d, It can also be measured by 27d '. When the measurement object is different and the combination of the strain sensor parts is the same, the configuration of the Wheatstone bridge is different. That is, in this embodiment, two pairs of strain gauges, each pair of which is a pair, that is, a total of four strain gauges are provided in each direction of the X axis, the Y axis, and the Z axis. , X-axis, Y-axis, and Z-axis direction translation forces and moments around these axes are measured.

The force sensor according to the present embodiment is configured as described above. Next, the operation and effect will be described.
In the force sensor 16 according to the present embodiment, the sensor body 18 includes the measurement beam portions 22a to 22d and the support beam portions 24a to 24d that form a pair and extend in a cross shape from the central shaft portion 21, and the measurement beam portions 22a to 22d. 22d and the support beam portions 24a to 24d constitute a sensor structure having a structure connected by connecting portions 23a to 23d. With such a sensor structure, the following effects can be obtained.

2 and 3, it is assumed that a moment around the X-axis acts on the sensor body 18 from the leg tip portion 15 via the load acting portion 20.
At this time, not only the measurement beam portions 22b and 22d are deformed, but also the support beam portions 24b and 24d connected by the connection portions 23b and 23d are simultaneously deformed. That is, since the load due to the moment is distributed to the measurement beam portions 22b and 22d and the support beam portions 24b and 24d, the rigidity of the measurement beam portions 22b and 22d with respect to the moment can be relatively increased. The same applies when a translational force in the X-axis direction is applied.

  In the present embodiment, in order to disperse the load due to the moment and the translational force in this way, four support beam portions 24a to 24d are provided together with the measurement beam portions 22a to 22d. Even when moments and translational forces in all directions around the Z axis and the Z axis are applied, the rigidity can be increased.

  In the present embodiment, the measurement beam portions 22a to 22d and the support beam portions 24a to 24d are each a set of four, but the present invention is not limited to this.

  By increasing the number of the measurement beam portions 22 (hereinafter, the subscripts of lowercase letters are omitted if they are not particularly distinguished, the same applies to the support beam portions, etc.) and the support beam portions 24, the individual measurement beam portions 22, Since the load applied to the support beam portion 24 is further dispersed, the rigidity of the sensor body 18 with respect to the moment can be further increased.

  The upper limit of the number of the measurement beam portions 22 and the support beam portions 24 is related to the thickness of the beam, but can be increased until the adjacent measurement beam portions 22 (or support beam portions 24) overlap each other.

On the other hand, when the number of measurement beam portions 22 (or support beam portions 24) is small, the load applied to each measurement beam portion 22 increases, so that the amount of bending of the measurement beam portion 22 increases, and the strain sensor. It is possible to improve the detection sensitivity of the distortion amount of the units 27 and 28.
Of course, when the number of the measurement beam portions 22 is two or less, the load in all directions cannot be received and the rigidity against the moment is reduced, so the minimum number is three.

  The above is the relationship between the number of measurement beam portions 22 (or support beam portions 24) and the rigidity and detection sensitivity of the sensor main body 18. The material of the measurement beam portions 22 and the support beam portions 24 is the same as that of the central shaft portion 21. The detection sensitivity can be enhanced by using different metal materials, although the same may be used.

  For example, by using a metal material having a Young's modulus lower than that of the central shaft portion 21 as the material of the measurement beam portion 22 and the support beam portion 24, the measurement beam portion 22 and the support beam are maintained while maintaining the strength of the central shaft portion 21. The part 24 can be easily bent, and the detection sensitivity of the strain amount of the strain sensor parts 27 and 28 can be improved.

  Further, in the present embodiment, the measurement beam portion 22 and the support beam portion 24 are arranged equiangularly so as to form a cross around the central axis portion 21, and the central axis portions of the measurement beam portion 22 and the support beam portion 24 are arranged. The radial intervals with respect to the axial center (center axis) of 21 are located radially so that the ends thereof are located at the apexes of the square. With such an arrangement, it is possible to avoid a load from being concentrated on a part of the measurement beam portion 22 and the support beam portion 24 and to prevent damage. Further, since the deformation amount of the measurement beam portion 22 is symmetric about the axis of the central shaft portion 20 regardless of the direction of the force acting on the load acting portion 20, the force direction can be accurately measured. it can. When the number of the measurement beam portions 22 and the support beam portions 24 is other than 4, the end portions in the radial direction of the support beam portions 24 are evenly spaced so as to form regular vertexes. .

  As described above, according to this embodiment, in order to support the weight of the robot body 12 as shown in FIG. 1 with the legs 14, the walking robot 10 in which a large moment acts from the floor surface 13 during walking. Thus, the force sensor 16 incorporated in the leg tip 15 can measure the translational force and the moment with high accuracy without being damaged.

(Second Embodiment)
Next, a force sensor according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a diagram showing the measurement beam portion 22 and the support beam portion 24 that form a pair when the sensor body 18 of the force sensor 16 according to the second embodiment is viewed from the X-axis direction. The force sensor 16 according to the first embodiment has a set of support beam portions 24 when a plurality of support beam portions 24 at the same position in the axial direction (Z-axis direction) of the central shaft portion 21 are taken as a set. A sensor body 18 having a one-stage structure is provided.
In contrast, the force sensor 16 according to the second embodiment is an embodiment in which a plurality of sets of support beam portions 24 having different positions in the Z-axis direction have a multistage structure. In FIG. 4, the support beam portion 24 has two stages, but it may be three or more stages.

  According to the second embodiment as described above, the translational force and the force due to the moment acting on the load acting portion 20 are distributed to the measuring beam portion 22 and the support beam portions 24 in a plurality of stages. 22, the force applied to one of the support beam portions 24 is reduced, and the rigidity can be further increased as compared with the case of the one-stage support beam portion 24.

(Third embodiment)
Next, a force sensor according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a diagram showing the measurement beam portion 22 and the support beam portion 24 that form a pair when the sensor body 18 of the force sensor 16 according to the third embodiment is viewed from the X-axis direction.
The force sensor 16 according to the third embodiment is an embodiment in which the measurement beam portion 22 is easily bent by forming a slit in the measurement beam portion 22.

As shown in FIG. 5, a slit 30 is opened at a portion of the measurement surface 26 parallel to the YZ plane of the measurement beam portion 22 where there is no strain sensor portion, and the slit 30 extends the measurement beam portion 22 vertically. It is designed to penetrate. In this case, the slit 30 corresponds to the measurement surface 25 and the strain sensor portions 27 and 27 ′ arranged on the measurement surface 25 ′ behind the measurement surface 25, and penetrates in parallel with the measurement surfaces 25 and 25 ′. .
Similarly, a slit 31 is formed so as to penetrate the measurement surface 26 so as to correspond to the strain sensor portions 28 and 28 ′ disposed on the measurement surfaces 26 and 26 ′.
Moreover, it is preferable that the support beam portion 24 is also formed with a slit 32 penetrating in the X-axis direction.
Similar slits are formed in the measurement beam portion 22 and the support beam portion 24 other than those shown in FIG.

  According to the third embodiment as described above, since the slits 30 and 31 are formed in the measurement beam portion 22 and the slit 32 is formed in the support beam portion 24, the measurement beam portion 22 and the support beam portion are bent. Thus, the amount of distortion generated in the strain sensor units 27 and 28 can be increased, and the detection sensitivity can be improved.

(Fourth embodiment)
Next, a force sensor according to a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a view showing the measurement beam portion 22 and the support beam portion 24 that form a pair when the sensor body 18 of the force sensor 16 according to the fourth embodiment is viewed from the X-axis direction.
The force sensor 16 according to the fourth embodiment is an embodiment in which the measurement beam portion 22 is easily bent by forming a reduced thickness portion on the measurement beam portion 22.
As shown in FIG. 6, the thickness between the measurement surfaces 25 and 25 ′ of the measurement beam portion 22 is reduced as compared with the other portions. The reduced measurement surfaces 25 and 25 ′ correspond to the strain sensor portions 27 and 27 ′.
Similarly, the measurement surfaces 26 and 26 'are also reduced in thickness corresponding to the strain sensor portions 28 and 28' disposed on the measurement surfaces 26 and 26 '. Further, it is preferable that a similar thickness reduction portion 34 is also formed in the support beam portion 24.
Similar thickness reduction portions are formed in the measurement beam portion 22 and the support beam portion 24 other than those shown in FIG.

  According to the fourth embodiment as described above, the measurement surfaces 25, 25 ′, 26, and 26 ′ of the measurement beam portion 22 are portions where the thickness is reduced, and the support beam portion 24 is also reduced in thickness. Therefore, the measurement beam portion 22 and the support beam portion 24 are easily bent, and the amount of strain generated in the strain sensor portions 27, 27 ′, 28, and 28 ′ can be increased, and the detection sensitivity can be increased. Can be improved.

(Fifth embodiment)
Next, a force sensor according to a fifth embodiment of the present invention will be described with reference to FIG.

FIG. 7 is a diagram showing the measurement beam portion 22 and the support beam portion 24 that form a pair when the sensor body 18 of the force sensor 16 according to the third embodiment is viewed from the X-axis direction.
In the force sensor 16 according to the fifth embodiment, an R portion 36 is formed at the connecting portion between the measurement beam portion 22 and the connecting portion 23, and an R portion 37 is provided at the connecting portion between the support beam portion 24 and the connecting portion 23. This is an embodiment formed. In addition, the same R part is formed also in the connection part of the measurement beam part 22, the support beam part 24, and the connection part 23 except having been illustrated in FIG.

  According to the fifth embodiment as described above, translation force and moment are applied to the sensor body 18 at the connection portion between the measurement beam portion 22 and the coupling portion 23 and at the connection portion between the support beam portion 24 and the coupling portion 23. In this case, the stress is easily concentrated, but by forming the R portions 36 and 37, the stress concentration can be relaxed and the measurement beam portion 22 and the support beam portion 24 are prevented from being broken. Can do.

(Sixth embodiment)
FIG. 8 shows a force sensor according to a sixth embodiment of the present invention. FIG. 8 is a diagram showing the positional relationship between the measurement beam portion 22 and the support beam portion 24 when the force sensor 16 according to the sixth embodiment is viewed from the Z-axis direction.

The force sensor 16 according to the first embodiment is an embodiment in which each support beam portion 24 is connected to each measurement beam portion 22 by the connecting portion 23 in the same phase.
The sixth embodiment is an embodiment in which each support beam portion 24 is connected to each measurement beam portion 22 by an oblique connection portion 23 so as to be deviated, for example, by 45 ° around the central shaft portion 21. is there.

According to the sixth embodiment configured as described above, there are four end portions of each measurement beam portion 22 and end portions of each support beam portion 24 on the inner peripheral surface of the fixing portion 19 that fixes the sensor body 18. The contact is made at a total of four places, that is, eight places, and the contact places are doubled as compared with the first embodiment. Thereby, the direction which supports the sensor main body 18 with respect to the acting translational force and moment increases, and rigidity can be improved more.
The present embodiment can be similarly applied to the case where the number of the measurement beam portions 22 and the support beam portions 24 is other than three or five.

(Seventh embodiment)
Next, a force sensor according to a seventh embodiment will be described with reference to FIG. In FIG. 9, the same components as those in FIG. 3 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The seventh embodiment is an embodiment in which strain sensors for measuring moments about the X axis and moments about the Y axis are arranged on the four side surfaces of the central shaft portion 21.

  In the seventh embodiment, of the eight side surfaces of the central shaft portion 20, the measurement surface 40b and the measurement surface 40d (the opposite surface of the measurement surface 40b) which are side surfaces parallel to the XZ plane are provided on the strain sensor 42b. 42d, and strain sensors 42c and 42a are disposed on the measurement surface 40c and the measurement surface 40a (opposite surfaces of the side surface 40c), which are side surfaces parallel to the YZ plane.

  When a moment around the + X axis acts on the sensor body 18, the measurement surface 40b extends and the measurement surface 40d contracts. When a moment around the -X axis, the measurement surface 40b shrinks and the measurement surface 40d extends. . Therefore, a moment around the X axis can be measured by configuring a Wheatstone bridge with the strain sensor portions 42a and 42d arranged on the measurement surfaces 40b and 40d and measuring the voltage thereof.

  Similarly, when a moment around the + Y axis acts on the sensor body 18, the measurement surface 40a expands and the measurement surface 40c contracts, and when a moment around the -Y axis, the measurement surface 40a contracts and the measurement surface 40c contracts. 40c extends. Therefore, the moment around the Y axis can be measured by configuring the Wheatstone bridge with the strain sensor portions 42a and 42c arranged on the measurement surfaces 40a and 40c and measuring the voltage thereof.

以上のような第７実施形態によれば、Ｘ軸回り、Ｙ軸回りのモーメントを中心軸部２１の歪みで測定するので、剛性が高い上に、第１実施形態と同様に、測定梁部２２が変形するだけでなく、連結部２６によって連結されている支持梁部２４も変形し、モーメントによる荷重は、測定梁部２２と支持梁部２４に分散されるので、相対的に、測定梁部２２のモーメントに対する剛性を高めることができる。 Other translational forces in the X-axis direction, Y-axis direction, Z-axis direction, and moments around the Z-axis direction can be measured in the same manner as in the first embodiment. Table 2 shows the measurement surface and strain sensor. Indicates the combination of parts.

According to the seventh embodiment as described above, since the moments around the X axis and the Y axis are measured by the distortion of the central shaft portion 21, the rigidity is high and the measurement beam portion is the same as in the first embodiment. 22 is not only deformed, but also the support beam portion 24 connected by the connecting portion 26 is deformed, and the load due to the moment is distributed to the measurement beam portion 22 and the support beam portion 24. The rigidity with respect to the moment of the part 22 can be increased.

(Eighth embodiment)
Next, a force sensor according to an eighth embodiment will be described with reference to FIGS. In FIG. 10, the same components as those in FIG. 2 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the first to seventh embodiments described so far, a strain sensor that detects elastic strain (deflection) is used as a deformation detection sensor that detects deformation of the measurement beam portion 22 of the sensor body 18 due to the action of translational force and moment. In this embodiment, the detected elastic strain is converted into force and moment.
On the other hand, in the eighth embodiment, a displacement sensor provided on the central shaft portion 21 as follows is applied as a deformation detection sensor for detecting deformation of the measurement beam portion 22 of the sensor body 18 due to the action of translational force and moment. In this embodiment, the translational force and the moment are measured.

  FIG. 10 shows a force sensor according to an eighth embodiment. In the sensor body 18, a holding plate 51 that holds the receiving portion 50 of the displacement sensor is fixed to the inner diameter portion of the leg portion 14 at a predetermined interval in the + Z-axis direction on the opposite side of the load acting portion 20. Yes. On the other hand, a transmission unit 52 of a displacement sensor is disposed on the end surface of the central shaft portion 21 of the sensor body 18 so as to face the reception unit 50, and the reception unit 50 and the transmission unit 52 constitute a displacement sensor pair. doing.

  The sensor body 18 is the same as that in the first embodiment. However, in the case of the eighth embodiment shown in FIG. 10, the measurement beam portion 22 is an embodiment in which no strain sensor portion is arranged. In addition, the structure of the sensor body according to the second to sixth embodiments can be applied to the structure of the sensor body 18 itself.

In this force sensor, when a translational force in the + Z-axis direction acts on the sensor main body 18 via the load acting portion 20, the measurement beam portion 22 and the support beam portion 24 are bent, and the central shaft portion 21 is displaced in the + Z direction. At this time, the transmission unit 52 of the displacement sensor approaches the reception unit 50. Therefore, the translational force in the + Z-axis direction can be measured by detecting the distance between the reception unit 50 and converting it to a force.
Similarly, in the case of the translational force in the −Z-axis direction, the displacement is performed in the direction of the central axis 21 −Z, and the transmission unit 52 of the displacement sensor moves away from the reception unit 50. The translational force in the −Z axis direction can be measured.

  The above description is the description of the measurement principle of the eighth embodiment, but a plurality of displacement sensors for measuring moments together with the translational force are arranged as shown in FIG.

Here, FIG. 11A shows the arrangement of the transmission units 52a to 52e of the displacement sensor when the central shaft portion 21 of the sensor body 18 is viewed from above (from the −Z-axis direction), and FIG. It is a figure which shows arrangement | positioning of the receiving parts 50a thru | or 50e of a displacement sensor seeing from + Z-axis direction. In this embodiment, five sets of displacement sensors are arranged.
The transmitters 52a to 52d are arranged on the end surface of the central shaft 21 so as to form the vertices of a square centered on the axis of the central shaft 21, and the receivers 50a to 50d are respectively connected to the transmitters 52a to 52d in the Z axis. It is arranged on the holding plate 52 at a position that faces the direction with a predetermined distance apart. The receiving unit 50e and the transmitting unit 52e are arranged opposite to each other on the central axis of the central shaft unit 21.

The two sets of displacement sensors including the receiving unit 50a and the transmitting unit 52a, and the receiving unit 50c and the transmitting unit 52c are pairs that are aligned in the X-axis direction and measure moments around the Y-axis. When a moment around the + Y axis acts on the sensor body 18, the transmission unit 52a moves away from the reception unit 50a, and at a moment around the -Y axis, the transmission unit 52a approaches the reception unit 50a. The moment of rotation can be measured.

  Similarly, the two sets of displacement sensors including the receiving unit 52b and the transmitting unit 50b, and the receiving unit 52d and the transmitting unit 50d are pairs that are aligned in the Y-axis direction and measure moments around the X-axis. When a moment around the + X axis acts on the sensor body 18, the transmission unit 52b approaches the reception unit 50b, and at a moment around the -X axis, the transmission unit 52d moves away from the reception unit 50d. The moment of rotation can be measured.

なお、表３には挙げていないＸ軸方向、Ｙ軸方向の並進力を測定できるようにするには、図３に示した第１実施形態のように、測定梁部２２ｂ、２２ｄにはＸ軸方向の並進力を測定する歪みセンサ部２８ｂ、２８ｂ’、２８ｄ、２８ｄ’を配置し、測定梁部２２ａ、２２ｃにはＹ軸方向の並進力を測定する歪みセンサ部２８ａ、２８ａ’、２８ｃ、２８ｃ’を配置するようにしてもよい。 Summarizing the above, Table 3 shows the translational force and moment that can be measured by the force sensor of this embodiment, and the combinations of the sensors.

In addition, in order to be able to measure the translational forces in the X-axis direction and the Y-axis direction not listed in Table 3, as in the first embodiment shown in FIG. Strain sensor units 28b, 28b ', 28d, 28d' for measuring the axial translational force are arranged, and the strain sensor units 28a, 28a ', 28c for measuring the translational force in the Y-axis direction are arranged on the measurement beam units 22a, 22c. , 28c ′ may be arranged.

  Also in the eighth embodiment as described above, when a moment about the X axis or the Y axis or a translational force in the Z axis direction acts on the sensor body 18 from the leg tip portion 15 via the load acting portion 20, These moments and translational forces can be measured.

  Moreover, in the sensor body 18, as in the first embodiment, not only the measurement beam portion 22 is deformed, but also the support beam portion 24 connected by the connection portion 26 is deformed, and the load due to the moment is measured by the measurement beam portion. Accordingly, the rigidity of the measurement beam portion 22 with respect to the moment can be relatively increased.

  Thus, in order to support the weight of the robot body with the legs, it is a force sensor incorporated in the leg tip portion 15 of the walking robot 10 shown in FIG. However, the translational force and moment can be measured with high accuracy without damage.

  The force sensor according to the present invention has been described with reference to the preferred embodiment applied to a multi-legged walking robot. However, the present invention can also be applied to various robots and manipulators. Also, these embodiments are given as examples and are not intended to limit the scope of the invention. Of course, the novel apparatus, method and system described in the specification can be implemented in various forms, and various omissions, substitutions and changes can be made without departing from the spirit of the present invention. is there. The claims and their equivalents are intended to cover the embodiments or improvements thereof within the spirit of the invention.

  DESCRIPTION OF SYMBOLS 10 ... Multi-legged walking robot, 12 ... Robot main body, 13 ... Floor surface, 14 ... Leg part, 15 ... Leg tip part, 16 ... Force sensor, 18 ... Sensor main body, 19 ... Fixed part, 20 ... Load action part, DESCRIPTION OF SYMBOLS 21 ... Center axis part, 22 ... Measurement beam part, 23 ... Connection part, 24 ... Supporting beam part, 25 ... Measurement surface, 26 ... Measurement surface, 27 ... Strain sensor part, 28 ... Strain sensor part, 30 ... Slit, 31 ... Slit, 32 ... Slit, 36 ... R part, 37 ... R part, 50 ... Displacement sensor receiver, 52 ... Displacement sensor transmitter

Claims (7)

In a force sensor that measures at least one of three orthogonal forces acting on a manipulator structure and moments around each axis,
A load acting part that receives the action of force,
A central shaft portion to which the load acting portion is connected coaxially;
At least three measurement beam portions extending radially from the central shaft portion in a radial direction;
At least three support beam portions that are arranged in the axial direction of the central shaft portion at a distance from the load acting portion and extend radially from the central shaft portion;
A connecting part for connecting the ends of the measurement beam part and the support beam part and closely contacting the fixed part of the structure;
A deformation detection sensor for detecting deformation of the measurement beam portion due to the force acting on the load acting portion;
A force sensor characterized by comprising:   The force sensor according to claim 1, wherein the deformation detection sensor is a strain detection unit that is disposed in the measurement beam unit and detects deformation of the measurement beam unit.   3. The measurement beam part is formed with a slit penetrating the measurement beam part in parallel to the measurement surface, corresponding to the position of the strain sensor on the measurement surface. Force sensor.   The force sensor according to any one of claims 1 to 3, wherein a thickness reduction portion is formed on the measurement surface of the measurement beam portion at a position where the strain sensor is disposed.   The measurement beam portion and the support beam portion are connected by the connection portion so as to be deviated from each other by a predetermined angle about the axis of the central shaft portion. The force sensor according to any one of the items.   The force sensor according to claim 1, wherein the central shaft portion has a measurement surface that is deformed by force or moment, and a strain sensor is disposed on the measurement surface.   The displacement detection sensor is a displacement detection unit that detects a change based on a change in a distance between a pair of displacement sensors by a pair of displacement sensors paired at a distance in the axial direction of the central shaft portion. The force sensor according to 1.

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