JP3459939B2 - Force sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, forces in the x, y and z axis directions acting on a fingertip portion or an arm portion of a robot and x,
The present invention relates to a force sensor for detecting moments around y and z axes.

[0002]

2. Description of the Related Art As a sensor for detecting a force or a moment, as shown in FIG. 19 (a), for example, a parallel slit provided with a rectangular slit 1 penetrating in the z-axis direction (direction orthogonal to the paper surface). A flat plate type sensor 2 is known. When the translational force f in the y-axis direction is applied to the sensor 2, the relationship between the position in the x-axis direction and the strain on the member surface is line symmetric with respect to the y-axis as shown by (b) in the figure. , And the upper and lower parts have opposite signs. Here, the strain becomes positive when the stress in the tensile direction acts, and becomes negative when the stress in the compression direction acts. Further, the relationship between the position in the X-axis direction and the strain when the moment m about the z-axis acts on the sensor 2 is symmetric with respect to the origin, as shown by (c) in the figure. The solid lines in (b) and (c) of FIG.
Of the upper part, that is, the upper surface P, and the dotted line represents the lower part, that is, the lower surface Q.

As shown in FIGS. 19 (b) and 19 (c), since strain increases at the boundary between the slit 1 and the sensor material, strain detecting elements such as strain gauges A to H are usually attached to this boundary. The strain of the sensor 2 is detected. Here, the strain detected by each strain gauge A to H is ε
Let _{A to} ε _H. Equivalent strain ε _f due to force f in the y-axis direction
In the detection, in order to cancel the distortion epsilon _m by moment m around the z-axis, it is possible to use either the addition value or subtraction value in the following formula (1). ε _f = −ε _A −ε _B , ε _C + ε _D , ε _E + ε _F , −ε _G −ε _H , −ε _A + ε _D , −ε _B + ε _C , ε _E −ε _H , ε _F −ε _G (1) When the force (external force) is positive, the equivalent strain ε _f is output as positive, and when the moment (external moment) is positive, the equivalent strain ε _m is output as positive.

On the other hand, in the detection of the equivalent strain epsilon _m by moment m around the z-axis, in order to cancel an equivalent strain epsilon _f by y-axis direction force f, any of the addition in the following formula (2) Values or subtracted values can be used. _{ε m = -ε A -ε D,} ε B + ε C, -ε A + ε B, ε C -ε D ...... (2) In addition, the detection of the equivalent strain epsilon _m by moment m, the following equation (3) It can also be done by. ε _m = −ε _A −ε _F , ε _B + ε _E , ε _C + ε _H , −ε _D −ε _G , −ε _A + ε _H , ε _B −ε _G , ε _C −ε _F , −ε _D + ε _E , Ε _E + ε _H , −ε _F −ε _G , ε _E −ε _F , −ε _G + ε _H …… (3)

Therefore, equations (1) and (2) or equation (1)
By selecting the addition value or the subtraction value one by one from (3), the equivalent strain ε due to the force f can be expressed by the following equation 1.
equivalent strain epsilon _m by _f and the moment m can be detected independently. However, when the formula (3) is used, the output may be small.

[Equation 1]

Next, using the above formula (1) or (2),
Equivalent strain ε_fOr ε_mTo use when seeking
The structural example of a Toston bridge circuit is shown. FIG. 20 (a)
Are strain gauges at positions A and B in (a) of FIG.
Provided, ε in equation (1)_f= Ε _A+ Ε_BThe strain ε
_fIn the example of obtaining
Equivalent strain gauges A and B are arranged at one diagonal position,
Two fixed resistors R on the other diagonal position₁, R₂Place
Input voltage E_inOutput voltage E according to_outAnd measure ε
_fIs to seek.

FIG. 20B shows ε _m = ε _A in the equation (2).
This is an example of obtaining the equivalent strain ε _m by using + ε _D. Further, (c) in the figure is an example of obtaining the equivalent strain ε _m by using ε _m = ε _A −ε _B in the equation (2). In this case, the strain gauge A and the strain gauge A are provided at adjacent positions in the Wheatstone bridge circuit. B is arranged, and the fixed resistor R is arranged at other positions. Further, (d) in the figure is ε _f = ε _A −ε _D in the equation (1).
This is an example of finding the equivalent strain ε _f using.

The parallel plate type sensor 2 described above is capable of detecting the translational force f in the y-axis direction and the moment m about the z-axis.
It is a component force sensor, and x,
In order to detect the forces and moments in the y- and z-axis directions, that is, the 6-component force, it is necessary to have a structure in which a plurality of the above-described sensors 2 are combined. Conventionally, a so-called three-dimensional cross sensor 3 shown in FIG. 21 is known as a combination of a plurality of parallel plate type sensors.

Since the three-dimensional cross sensor 3 is formed by integrating the parallel plate type sensors 2 in a three-dimensional manner in the directions of the three axes x, y, and z, the six-component force is independently detected. In addition, when a strain gauge is used to detect the force, the force applied to the sensor 3 and the corresponding strain output are in a proportional relationship, and the detection accuracy is also good. However, since the three-dimensional cross sensor 3 has a complicated structure, it is difficult to process and it is difficult to reduce the size.

Further, conventionally, as shown in FIG. 22, a first cross-shaped sensor 6 is arranged between a disc-shaped upper connecting portion 4 and an intermediate connecting member 5, and at the lower portion of the intermediate connecting member 5. There is known a 6-component force sensor 9 in which a second cross-shaped sensor 7 is arranged and a lower connecting portion 8 is provided at the center of the lower surface of the second cross-shaped sensor 7 (see Japanese Patent Laid-Open No. 1-156632). ). The sensor 9 has an upper connecting portion 4 connected to one rigid body and a lower connecting portion 8 connected to the other rigid body, and is used for measuring a 6-component force between two rigid bodies.

As shown in FIGS. 23 and 24, the first and second cruciform sensors 6 and 7 are formed by intersecting two parallel plate type sensor elements 6a, 6b and 7a, 7b in a cruciform shape. The slits 6c penetrating in the thickness direction are formed in the sensor elements 6a, 6b of the first cross-shaped sensor 6, and the sensor elements 7a, 7b of the second cross-shaped sensor 7 are formed.
A slit 7c is formed therethrough in the width direction.
In addition, 10 is a strain gauge.

Both ends of one sensor element 6a of the first cross sensor 6 are connected to the upper connecting portion 4 by using holes 6d, and both ends of the other sensor element 6b of the first cross sensor 6 are connected. It is connected to the intermediate connecting member 5. Further, both ends of both sensor elements 7a and 7b of the second cross-shaped sensor 7 are connected to the intermediate connecting member 5 using holes 7d. Therefore, each sensor element 6a in the 6-component force sensor 9,
A schematic representation of the connection relationship between 6b and 7a, 7b is shown in FIG.
5, the sensor element 6b of the first cross sensor 6
Both ends of the pair of sensor elements 7a and 7b of the second cross-shaped sensor 7 are connected by the intermediate connecting member 5.

[0013]

By the way, in the above-described 6-component force sensor 9, the second cross-shaped sensor 7 is replaced by z in FIG.
It is used to detect the translational force in the axial direction and the moments around the x and y axes. Specifically, the sensor element 7b of the second cross-shaped sensor 7 detects the moment around the x-axis,
The sensor element 7a is used to detect the moment about the y-axis. In this case, the sensor element 7 is connected by the intermediate connecting member 5.
Since both longitudinal ends of a and 7b are connected,
In the design of the second cross-shaped sensor 7, it is required to sufficiently reduce the torsional rigidity of the second cross-shaped sensor 7 in order to increase the sensitivity of moment detection about the x-axis and the y-axis. The rigidity of the cross-shaped sensor 7 as a whole is required to be increased to some extent, and it is necessary to satisfy the two contradictory requirements. Therefore, there is a problem that the design of the second cross-shaped sensor 7 becomes difficult.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and facilitates miniaturization, and each component is designed independently to identify each force component such as 6-component force. An object of the present invention is to provide a force sensor that can be independently detected. for that reason,
The force sensor according to claim 1 of the present invention is a measurement object 2
Placed between two rigid bodies and acting between them, x,
A six-component force sensor that detects forces in the y- and z-axis directions and moments around the x, y, and z-axes, and one and the other of the sensors extending respectively in the first axis and the second axis directions orthogonal to each other. A first cross-shaped sensor in which elements are integrated by intersecting each other in a cross shape in a longitudinal direction, and one and the other sensor elements extending in the first axial direction and the second axial direction, respectively, are provided in the longitudinal intermediate portions. And are integrated with each other by crossing in a cross shape between the first shaft and the second cross sensor with the first cross sensor.
A second cross-shaped sensor, which is arranged in parallel at a distance in the third axial direction orthogonal to both axes, and two longitudinal ends of one of the sensor elements of the first and second cross-shaped sensors are connected to each other. A pair of connecting portions, a first connecting portion that connects both longitudinal ends of the other sensor element in the first cross sensor and the one rigid body, and a longitudinal direction of the other sensor element in the second cross sensor. A second connecting portion that connects both end portions and the other rigid body is provided, and one of the first and second cross-shaped sensors has a translational force in the third axial direction and a rotational force about the first axis and the second axis. Used to detect each moment, the first and second
The other one of the cross-shaped sensors is characterized by being used for detecting each translational force in the first and second axis directions and the moment about the third axis.

According to a second aspect of the present invention, in the structure of the first aspect, one or the other sensor element of the first or second cross sensor is a parallel plate in which a slit is formed in a substantially rectangular parallelepiped sensor material. Of the first and second cross-shaped sensors, a slit penetrating in the second axial direction is formed in the one sensor element and the other sensor element is provided with the first sensor element. A slit penetrating in the axial direction is formed, and a slit penetrating in the third axial direction is formed in each of the one and the other sensor elements of the other of the first and second cross-shaped sensors. It is a thing.

A force sensor according to a third aspect is the force sensor according to the first or second aspect, characterized in that the first and second cross-shaped sensors and the connecting portion are integrally formed of the same material. Is.

A force sensor according to a fourth aspect of the present invention is arranged between two rigid bodies as an object to be measured, and the three-component force sensor detects the forces acting between the rigid bodies in the x-, y-, and z-axis directions. And a cross-shaped sensor in which one and the other sensor elements extending in the first axis direction and the second axis direction which are orthogonal to each other are made to intersect each other in a cross shape in the longitudinal middle portion, and are integrated. In the cross-shaped sensor, the first connecting portion connecting both ends in the longitudinal direction of the other sensor element and the one rigid body by point contact, and connecting the both ends in the longitudinal direction of the one sensor element in the cross sensor and the other rigid body. A second connecting portion for connecting the first shaft , the second shaft, and the second shaft to the second shaft.
It is characterized in that the origin of the coordinate system composed of the third axis orthogonal to the direction is determined so as to coincide with the connection point of the first connection portion by point contact with the one rigid body.

In the force sensor according to a fifth aspect of the present invention, in the structure of the fourth aspect, one and the other sensor elements of the cross sensor are parallel plate type sensor elements in which slits are formed in a sensor material having a substantially rectangular parallelepiped shape. And a slit penetrating in the second axial direction is formed in the one sensor element, and a slit penetrating in the first axial direction is formed in the other sensor element. .

Here, according to the structure of claim 4 or 5,
The reason why the translational force in the first to third axis directions can be detected will be described. The origin O ₁ of the coordinate system Σ ₁ of the sensor 2 shown in FIG. 18 is the center position of both slits 1 in the x1 axis direction, the center position in the thickness direction in the y1 axis direction, and the center position in the depth direction in the z1 axis direction. It is set to be. As is clear from the above description, the sensor 2 originally has a role as a two-component force sensor that detects the translational force in the y1 axis direction and the moment about the z1 axis.

By the way, even if the coordinate system Σ ₁ is translated in the z1 axis direction and the coordinate system Σ whose origin is O is set, y1
For the translational force in the axial direction and the moment about the z1 axis, those measured in the coordinate system Σ ₁ can be used as they are. That is, assuming that the translational force and moment in the coordinate system Σ ₁ are f _y1 and m _z1 , respectively, and the translational force and moment in the coordinate system Σ are f _y and m _z , respectively, f _y = f _y1 , m _z = m _z1. (4)

On the other hand, if the coordinate system Σ ₁ is moved in parallel in the y1 axis direction to make the coordinate system Σ ′ whose origin is O ′, it may be possible to detect the translational force in the x ′ axis direction. is there. That is, the moment about the z1 axis is m _z1 , z ′
Moment about the axis is m _z ', translational force in the x'axis direction is f
_When the distance in the y1 axis direction between _x ′ and both coordinate systems Σ ₁ and Σ ′ is L, the relationship of the following expression (5) is established. m _z1 = m _z '-f _x ' L (5)

From equation (5), the translational forces f _x 'and f _y '
And the moment m _z 'does not act, the following equation (6) is established. f _y '= f _y1 , f _x ' = -m _z1 / L (6) In this equation (6), the translational forces f _x 'and f _y ' act on O'and the moment m _z 'acts. If not, the sensor 2 should be used as a two-component force sensor that detects the translational force in the two directions of the x′-axis direction and the y′-axis direction, in other words, the translational force in the two directions of the longitudinal direction and the thickness direction of the sensor 2. Means that you can.

In the structure of claim 4 or 5, the configuration of FIG.
The sensor 2 and the like as above are used as respective sensor elements, and the sensor elements are made to intersect with each other in the first axis direction and the second axis direction so as to be integrated with each other, whereby translational forces in the first axis to the third axis directions can be detected.
It is used as a force sensor. That is, the one sensor element extending in the first axial direction can detect translational forces in two directions of the first axial direction (longitudinal direction) and the third axial direction (thickness direction), and the other sensor element extending in the second axial direction. Since the sensor element can detect translational forces in the second axis direction and the third axis direction, it is possible to detect translational forces in the three directions of the first axis to the third axis as a whole. Although the translational force in the third axis direction is detected redundantly,
This point is not particularly problematic.

In the fourth aspect, the origin of the coordinate system composed of the first axis to the third axis is determined so as to coincide with the connection point of the first connecting portion by point contact with the one rigid body. However, this means that the origin of the coordinate system deviates from the center position in the thickness direction of the cross sensor, which is the original position, in the third axis direction. Further, the first connecting portion is connected to the one rigid body by point contact,
This is the first point at the origin (connection point by point contact).
This is because a moment about the axis to the third axis is not generated, and by this, the above-mentioned formula (6) is established and a three-component force force sensor capable of detecting translational forces in three directions is configured. become.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below. As shown in FIG. 1, the 6-component force sensor 12 of the present embodiment includes a first cross-shaped sensor 13 and a 20th cross-shaped sensor 13 which are arranged in parallel with each other with a space in the z-axis (third axis) direction. The character sensor 14 is provided. The first and second cruciform sensors 13 and 14 are parallel plate type one sensor elements 13a and 14a extending in the x-axis (first axis) direction, and parallel plate type sensors extending in the y-axis (second axis) direction, respectively. The other sensor elements 13b and 14b are integrated at right angles to each other at their longitudinal intermediate portions.

The 6-component force sensor 12 further includes a sensor element 1 of one of the first and second cross sensors 13 and 14.
A pair of connecting portions 15 for connecting both longitudinal end portions of 3a and 14a, and one longitudinal end portion of the other sensor element 13b of the first cross sensor 13 to one rigid body, for example, a fingertip portion of a robot ( A pair of first for connecting to (not shown)
A connecting portion 16 and a pair of second connecting portions 17 for connecting both longitudinal ends of the other sensor element 14b of the second cross-shaped sensor 14 to the other rigid body, for example, a robot hand (not shown). Is equipped with.

In one sensor element 13a of the first cross-shaped sensor 13, rectangular slits 13d penetrating in the y-axis direction are formed on both sides of a central intersection 13c, and the other sensor element 13b. The rectangular slits 13e penetrating in the x-axis direction are formed on both sides of the intersection 13c. Further, one and the other sensor elements 14a, 14b of the second cross-shaped sensor 14 are provided with a pair of rectangular slits 14d, 14e penetrating in the z-axis direction on both sides of the central intersection 14c. There is.

The origin O of the coordinate system of the first cross-shaped sensor 13 in the six-component force sensor 12 is the center position of the intersection 13c in the x and y axis directions, and the first in the z axis direction. It is the center position of the cross sensor 13 in the thickness direction. Further, although the origin of the coordinate system of the second cross sensor 14 is originally the center position in the thickness direction of the second cross sensor 14, the origin of the second cross sensor 14 is determined from the above equation (4). The first cross-shaped sensor 13 is moved by moving in the z-axis direction.
Since the force and moment in the second cross sensor 14 do not change even if they coincide with the origin O, the origin of the coordinate system of the second cross sensor 14 can be considered to be the origin O.

When the 6-component force sensor 12 is divided into sensor elements of the cross sensors 13 and 14 and schematically shown, it becomes as shown in FIG. From the fingertip side of a robot, the first connecting portion 16, the other sensor element 13b of the first cross sensor 13, the one sensor element 13a, the connecting portion 15, and the one sensor element 14a of the second cross sensor 14, The force and the moment are transmitted in order of the other sensor element 14b, the second connecting portion 17, and the robot hand that is the fixed end of the 6-component force sensor 12.

In the present embodiment, each sensor element 13b, 13a, 14a, 14b, which is a two-component force sensor, is connected in series. In other words, the sensor elements 13 a and 13 b of the first cross sensor 13 and the sensor elements 14 a and 14 b of the second cross sensor 14 intersect with each other at the intersection portion 13.
c, 14c, and the two cross-shaped sensors 13, 14 are connected to each other only by one of the sensor elements 13a, 14a.
Are connected only at both longitudinal ends. Therefore, unlike the 6-component force sensor 9 (FIG. 24) of the conventional example, each sensor element 13a, 13b, 14a, 14b can be designed completely independently, and each sensor element is not a detection target. It should be designed to have as high a rigidity as possible with respect to the force and moment.

Specifically, for example, the first cross-shaped sensor 1
The other sensor element 13b of 3 has a translational force in the z-axis direction and x
Two strain gauges A are used to detect the moment around the axis ((b) in FIG. 2), and the translational force in the z-axis direction causes the other sensor element 13b to have the surface (that is, the upper surface) side of the other sensor element 13b.
3 and B3 are attached, and one strain gauge A4 and D4 are attached to the front surface side and the back surface (that is, the lower surface side) of the sensor element 13b for detecting the moment around the x-axis.

Each strain gauge has a slit 13
It is attached to a position corresponding to the end portion of the other sensor element 13b in the e direction near the middle portion in the longitudinal direction. The outputs of the strain gauges A3 and B3 are input to the same Wheatstone bridge circuit as in FIG. 20A, and the outputs of the strain gauges A4 and D4 are input to the same Wheatstone bridge circuit as in FIG. 14B. It In addition, in FIG. 2 (b)
In (e) to (e), the strain gauges shown in black are attached to the front surface side, and the strain gauges shown in hatching are attached to the back surface side.

The one sensor element 13a of the first cross sensor 13 is used for detecting the translational force in the z-axis direction and the moment about the y-axis ((c) in the figure), and the translational force in the z-axis direction. Two strain gauges A3 'on the surface side for the detection of
While B3 ′ is attached, one strain gauge A5, D5 is attached on each of the front surface side and the back surface side for detecting the moment around the y-axis. The connection of the strain gauges of each set to the Wheatstone bridge circuit is performed in the same manner as the strain gauges of the other sensor element 13b. As a precaution, a top view and a bottom view of the first cross sensor 13 are shown in FIGS. 3 and 4, respectively.

One of the sensor elements 14a of the second cross-shaped sensor 14 is used for detecting the translational force in the y-axis direction and the moment about the z-axis ((d) in the figure), and the translational force in the y-axis direction is detected. Two strain gauges A2 and B2 are attached to the back surface (side surface opposite to the front side of (a) in FIG. 2) for detection, and the back surface and front surface (FIG. Two strain gauges A6 and D6 are attached to the inside of 2 (a side surface on the front side).

The other sensor element 14b of the second cross-shaped sensor 14 is used for detecting the translational force in the x-axis direction and the moment about the z-axis ((e) in the figure), and the translational force in the x-axis direction. Two strain gauges A1 and B on the front side for detecting
1 is attached, while one strain gauge A is provided on each of the front surface side and the back surface side for detecting the moment around the z-axis.
6'and D6 'are attached. In the above-described configuration, the translational force in the Z-axis direction and the moment about the z-axis are detected in duplicate at each of two places, but this point is not a particular problem, and the structure of the 6-component force sensor 12 is not limited. It can be said that the merit of being able to simplify is much greater.

In actual detection, one of the strain gauges at the overlapping portion (for example, strain gauge A in (c) of FIG. 2) is used.
3'and B3 'and strain gauges A6' and B of (e) in the figure.
6 ') can be omitted, or four strain gauges in the overlapping portion can be used in one Wheatstone bridge circuit. For example, as shown in FIG.
When the four strain gauges A3, B3, A3 ′, B3 ′ in the first cross sensor 13 are used to detect the translational force in the z-axis direction, the strain gauges A3, B3 are connected in series at one diagonal position of the Wheatstone bridge circuit. , And the strain gauges A3 ′ and B3 ′ can be input in series at the other diagonal position. R ₃ and R ₄ are fixed resistors.

Further, the translational force in the z-axis direction is detected by the strain gauges A3 and B shown in FIG. 2B as shown in FIG. 5B.
3 may be connected to one diagonal position of the Wheatstone bridge circuit, and the strain gauges C ′ and D ′ may be connected to the other diagonal position. Here, the strain gauges C ′ and D ′ are the strain gauges A in FIG.
The gauges are attached to the back surface sides of B3 and B3, that is, the positions corresponding to the strain gauges A3 and B3 on the bottom surface side of the second sensor element 13b.

On the other hand, for example, when four strain gauges are used to detect the moment around the x-axis, the strain gauges A6 and D6 of FIG. 2 are connected to one pair of the Wheatstone bridge circuit as shown in (c) of FIG. The strain gauges A6 ′ and D6 ′ may be connected to the other diagonal positions, respectively. In addition, the detection of the moment around the x-axis is performed as shown in (d) of FIG.
6 may be connected to one diagonal position of the Wheatstone bridge circuit, and the strain gauges C ′ and B ′ may be connected to the other diagonal position. Here, the strain gauges C ′ and B ′ are the strain gauges A in FIG.
6, Strain gauges A6, D on the side opposite to D6
6 is a gauge attached to a position corresponding to 6.

It should be noted that this is merely an example of the mounting position of the strain gauge shown in FIG. 2, and the sensor elements 13b, 13a,
It is possible to attach strain gauges to 14a and 14b at various combined positions shown by (a) in FIG. 19 and the formula (1).

The force in the 6-minute force sensor 12 will be described below.
The relationship between the moment and the equivalent strain will be described. The relationship between force, moment and strain in the 6-component force sensor is expressed by the following mathematical expression 2.

[Equation 2]

Next, the relationship between the strain and the output voltage from the amplifier connected to the strain gauge through the Wheatstone bridge circuit is expressed by the following mathematical expression 3.

[Equation 3]

From the formula (7) in the formula 2 and the formula (8) in the formula 3, the following formula (9) is established. V = AF However, A = KC (9) In order to clarify the characteristic of the 6-component force sensor, the basic equation is normalized and the equation (10) in the following equation 4 is obtained from the equation (7). obtain. In designing, the strain is set to the elastic limit value when the desired rated force F is applied while satisfying the expression (10).

[Equation 4]

The equation (10) is the same as the equation (11) in the following equation (5).

[Equation 5]

[0044] The eigenvalue of C in equation (11) is       σ_i= 1, i = 1, 2, ..., 6 (12) And the condition number condC (maximum eigenvalue /
The smallest eigenvalue) is       condC = σ_max/ Σ_min= 1 …… (13) Becomes This has the same sensitivity for each component, which is ideal
It means a state. The actual 6-minute force sensor is
Lines that show characteristics although they deviate slightly from ideal due to various influences
Column C (see equation 2) or matrix A (see equation (9))
It may be used after setting. Ideal characteristics and design
When it is important to have a structure and the structure of the present invention is used,
In this case, even if it deviates a little, the characteristics close to the ideal can be realized.

In the above embodiment, each sensor element 13a, 13b, 14a, 14b is formed as a parallel plate type. However, as shown in FIG.
In order to reduce the thickness of the portion of the sensor element 13a having the slit 13d, grooves 13f may be provided at the upper and lower portions of the slit 13d. Further, it is not always necessary to provide the slit 13d or the like on each sensor element 13a or the like, and as shown in FIG.
The thickness of the entire sensor element 13a ′ or the like may be made smaller than that of the sensor element 13a or the like having the above. Also in this case, it is preferable to provide the groove 13f 'in the vicinity of the portion where the strain due to the force or the moment is actually detected.

The adjustment of the force rating of the sensor element 13a 'having no slit shown in FIG. 6B is mainly performed by adjusting the width c of the groove 13f' and the thin wall having the groove 13f 'shown in FIG. The thickness h'of the portion, the depth dimension d (dimension in the direction orthogonal to the paper surface) of the sensor element 13a ', etc. are adjusted, and the moment rating is adjusted by adjusting the center of the sensor element 13a', etc. in addition to the above c, h, d. It is adjusted using the distance b between the ends of the groove 13f 'and the groove 13f'. In this case, since b is independent of the force rating, the moment rating can be adjusted using b after determining the force rating using parameters other than b.

On the other hand, in the sensor element 13a having the slit 13d shown in FIG. 6A, the ratings of the force and moment can be determined by using the same parameters as described above. The rating can be adjusted by using the dimensions h and a in FIG. 6A instead of the thickness h ′, but it is rational because the rating can be increased without increasing the size of each sensor element 13a or the like.

[0048]

EXAMPLES Examples of the present invention will be described below. As shown in FIG. 7, the robot hand 20 has a plurality of, for example,
Three fingers 21 (only two are shown in FIG. 7) are provided. Each finger 21 has a plurality of joints 21d to 21d that connect the link portions adjacent to the plurality of link portions 21a to 21c in a rotatable manner.
21f, and the most distal joint 21f is 6 of the present invention.
It is connected to the fingertip member 23 via the force-force sensor 22. Then, an object (not shown) can be gripped between the fingertip members 23 of the three fingers 21 in accordance with the rotational movement of each of the joints 21d to 21f. At that time, the 6-component force sensor 22 detects the forces in the x, y, z axis directions and the moments about the x, y, z axes generated between the fingertip member 23 and the joint 21f. . The robot hand 20 may be rotatably supported by a wrist mechanism (not shown).

The 6-component force sensor 22 has a concrete shape, for example, as shown in FIG. 8, in which the first connecting portion 16 is the central hole 16a and the joint 21f at the most distal end side (one side). Rigid body) is rotatably connected. Further, in this embodiment, the first connecting portion 16 and the 6-component force sensor body 24 are integrally connected via the pair of connecting tips 16b, and each of these portions is super super duralumin. It is formed of a material such as.

As shown in FIGS. 9 and 10, a thick portion 16c is formed in the portion of the first connecting portion 16 near the connecting tip portion 16b, and the thick portion 16c has an arc shape centered on the hole 16a. Has a contour of. The pair of connection tip portions 16b are the first portion of the 6-minute force / force sensor main body portion 24.
The other cross-shaped sensor 13 is integrally connected to both ends in the longitudinal direction of the other sensor element 13b. In addition, the same reference numerals as those described above are given to the respective components of the 6-component force sensor body 24.

As shown in FIG. 11, the first cross-shaped sensor 1
In each of the sensor elements 13a and 13b of No. 3, the slit 13
d and 13e are provided. Also, FIGS.
As also shown in FIG. 1, one end of a pair of connecting portions 15 is integrally connected to both ends of the one sensor element 13 a, and the other end of these connecting portions 15 is one of the sensor elements in the second cross-shaped sensor 14. 14a is integrally connected to both ends in the longitudinal direction. Then, holes 14f are provided at both longitudinal ends of the other sensor element 14b of the second cross-shaped sensor 14.
The hole 14f is adapted to be connected to the other fingertip member 23, which is a rigid body, via the second connecting portion (not shown). In addition, the radial dimension A of the 6-component force sensor body 25 (FIG. 9) is, for example, about 10 mm and the axial dimension B.
Is, for example, about 10 mm, and the 6-minute force sensor can be sufficiently miniaturized.

In the above embodiment, the first connecting portion 16, the first cross-shaped sensor 13, the connecting portion 15 and the second cross-shaped sensor 14 are provided.
This has the advantage that the number of parts can be reduced and the miniaturization of the entire sensor can be promoted, etc., but the above-mentioned respective parts may be configured as separate members.
Further, the slits 13d and 13e in the first cross sensor 13 and the second cross sensor 14 shown in FIG. 1 or FIG.
And 14d and 14e are reversed in direction so as to penetrate the slits 13d and 13e of the first cross-shaped sensor 13 in the z-axis direction, while the slit 14 of the second cross-shaped sensor 14 is formed.
It is also possible to penetrate d and 14e in the y and x axis directions.

Next, a second embodiment of the present invention will be described. As shown in FIG. 15, in this embodiment, x, y, z
The present invention relates to a three-component force sensor 26 capable of detecting a translational force in the axial direction. The force sensor 26 is a cross-shaped sensor in which one and the other sensor elements 26a and 26b, each of which has a substantially rectangular parallelepiped shape extending in the x-axis direction and the y-axis direction, are integrated by intersecting each other in a cross shape at each longitudinal intermediate portion 26c. Slits 26d penetrating in the y-axis direction are formed on both sides of the intersection portion 26c in one sensor element 26a, and a slit 26d penetrating in the x-axis direction is formed in the other sensor element 26b.
e is formed.

Both ends in the longitudinal direction of the other sensor element 26b of the force sensor 26 are connected to the forked tip portion 27a of the first connecting portion 27. A ball 28 is provided on a base end portion 27b of the first connecting portion 27, and a spherical receiving portion is formed on one rigid body (not shown), and the ball 28 is rotatably supported by the receiving portion. As a result, a ball joint (universal joint) is formed between the base end portion 27b and the one rigid body. Further, the forked base end portion 30a of the second connection portion 30 is connected to both longitudinal end portions of one sensor element 26a of the force sensor 26, and the tip end portion 3 of the second connection portion 30 is connected.
0b is connected to the other rigid body (not shown).

In this case, assuming that the center position of the ball 28 is the origin O of the coordinate system, the ball 28 is rotatable with respect to the receiving portion of the one rigid body.
Only the translational forces in the y- and z-axis directions act, and the moments around the x-, y-, and z-axes do not act, and the above equation (6) is established for each sensor element 26a, 26b. The origin O is displaced in the z-axis direction from the center position in the thickness direction of each force sensor 26, which is a normal origin position in the force sensor 26.

FIG. 16 schematically shows the connection relation of each part around the force sensor 26. The origin O ₁ of the original coordinate system Σ ₁ with respect to the other sensor element 26b is the central position in the thickness direction of the sensor element 26b, and the sensor element 26b has a moment m _x1 about the x1 axis and a translational force f _{z1 in the} z1 axis direction. Should be used for the detection of However, in the present embodiment, the origin O of the coordinate system Σ is set to the center position of the ball 28, and the moment is not applied to the origin O. Therefore, the sensor element 26b coordinates the origin O. A two-component force sensor for detecting translational forces in the y direction and the z direction in the system Σ is configured.

That is, assuming that the translational forces in the y-axis direction and the z-axis direction in the coordinate system Σ are f _y and f _z , respectively, and the distance between the origins O ₁ and O is L, the following equation (6) is obtained. Expression (1
4) is established. f _z = f _z1 , f _y = −m _x1 / L (14) Similarly, if the origin O ₂ of the original coordinate system Σ ₂ of one sensor element 26a is the center position of the sensor element 26a in the thickness direction. , In this coordinate system Σ ₂ , the sensor element 26
a is to be used for detecting the translational force f _z2 in the z2 axis direction and the moment m _y2 about the y2 axis. However, in the present embodiment, the coordinate system Σ with the center position of the ball 28 as the origin O is used, and since no moment acts on the origin O, the translational forces in the x and z axis directions in the coordinate system Σ are f _x. ,
If f _z , the relationship of the following expression (15) is established from the above expression (6). f _z = f _z2 , f _x = _my2 / L (15)

From the expressions (14) and (15), the force sensor 2
It can be seen that 6 constitutes a three-component force sensor capable of detecting translational forces in the three directions of the x, y, and z axes. As described above, in the present embodiment, when it is necessary to detect only the translational forces in three directions, the force sensor can be configured with a simpler structure than the first embodiment.

FIG. 17 shows a third embodiment of the present invention. The force sensor 31 of this embodiment uses only one parallel plate type sensor element 31a having two slits 31b penetrating in the x-axis direction.
The upper surface side at both ends in the longitudinal direction of a is connected to one rigid body (not shown) using the same first connecting portion 27 and ball 28 as described above. Further, the lower surface side of the sensor element 31a in the longitudinal middle portion is connected to the other rigid body (not shown) through the second connecting portion 32.

Also in this case, the origin O of the coordinate system Σ is the ball 2
8 is the center position of the sensor element 31a, is deviated from the original origin O ₁ which is the intermediate position in the thickness direction of the sensor element 31a, and no moment acts on the origin O. And detecting the translational force in the z-axis direction 2
It becomes a force sensor. That is, assuming that the translational forces in the y-axis direction and the z-axis direction in the coordinate system Σ are f _y and f _z , respectively, and the distance between the origins O ₁ and O is L, the following equation (16) is obtained from the above equation (6). ) Is established. f _z = f _z1 , f _y = −m _x1 / L (16)

[0061]

As described above, according to the force sensor of claim 1 of the present invention, the other sensor element in the first cross sensor, the one sensor element, and the one sensor element in the second cross sensor, the other Since all the sensor elements of are connected in series, when a strain gauge is used to detect the force, the force applied to the 6-minute force sensor and the equivalent strain output corresponding to it have an ideal linear relationship, and each component is completely Has the advantage that it can be taken out independently. Moreover, since the design of each sensor element may be performed for each component of force and moment, it is easy to design according to the rating. Further, since the structure is simpler than that of the conventional so-called three-dimensional cross sensor, there is an advantage that the size can be easily reduced.

According to the force sensor of the second aspect, since each sensor element of the first and second cross-shaped sensors is a parallel plate type sensor element having a slit, there is an advantage that each sensor element can be configured easily and inexpensively. is there.

In the force sensor of the third aspect, the first and second cross-shaped sensors and the connecting portion are integrally formed, so that the number of parts can be reduced and the size can be reduced.

According to the force sensor of the fourth aspect, the origin position of the coordinate system is moved in parallel from the original origin position, and the moment is prevented from acting on the origin position.
It becomes possible to detect translational forces in three directions with a simple configuration using two cross-shaped sensors.

The force sensor of claim 5 has an advantage that the three-minute force sensor can be constructed with a simple configuration using one parallel plate type sensor.

[Brief description of drawings]

FIG. 1 is a perspective view showing a 6-component force sensor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing the connection relationship of each sensor element in the 6-component force sensor and showing an example of attaching a strain gauge to each sensor element.

FIG. 3 is a top view of a first cross-shaped sensor in the 6-component force sensor.

FIG. 4 is a bottom view of a first cross-shaped sensor in the 6-component force sensor.

FIG. 5 is an explanatory diagram illustrating a connection relationship between a strain gauge and a Wheatstone bridge circuit in the 6-component force sensor.

FIG. 6 is an explanatory diagram showing a modification of the sensor element according to the above embodiment.

FIG. 7 is an explanatory diagram showing a robot hand according to an embodiment of the present invention.

FIG. 8 is a perspective view showing a 6-component force sensor attached to the robot hand.

9 is a front view showing the 6-component force sensor of FIG. 8. FIG.

FIG. 10 is a partial cross-sectional side view showing the 6-component force sensor of FIG.

11 is a cross-sectional view taken along the line XI-XI of FIG.

FIG. 12 is a view on arrow XII in FIG.

13 is a sectional view taken along line XIII-XIII in FIG.

14 is a sectional view taken along line XIV-XIV in FIG.

FIG. 15 is a perspective view showing a three-component force sensor according to a second embodiment of the present invention.

16 is an explanatory diagram schematically showing the connection relationship of each part in the force sensor of FIG.

FIG. 17 is a perspective view showing a two-component force sensor according to a third embodiment of the present invention.

FIG. 18 is an explanatory diagram illustrating the principle of detecting a translational force in two directions with a parallel plate sensor.

FIG. 19 is an explanatory diagram showing a relationship between a parallel plate type sensor and each strain and position due to a translational force and a moment in the sensor.

20 is an explanatory diagram showing a connection relationship between the strain gauge and the Wheatstone bridge circuit when the strain gauge is attached to various positions of the sensor of FIG.

FIG. 21 is a perspective view showing a conventional three-dimensional cruciform six-component force sensor.

FIG. 22 is a front view showing another conventional 6-component force sensor.

23 is a plan view showing a first cross-shaped sensor in the sensor of FIG. 22. FIG.

24 is a plan view showing a second cross-shaped sensor in the sensor of FIG. 22. FIG.

FIG. 25 is an explanatory diagram showing a connection relationship of each sensor element in the 6-component force sensor of FIG. 22.

[Explanation of symbols]

12 6-minute force sensor 13 First cross sensor 13a One sensor element 13b The other sensor element 13d, 13e slit 14 Second cross sensor 14a One sensor element 14b the other sensor element 14d, 14e slit 15 Connection 16 First connection 17 Second connection part 22 6-minute force sensor 26 3 minute force sensor

Claims (5)

(57) [Claims] 1. A 6-minute unit which is arranged between two rigid bodies which are objects to be measured and which detects forces acting in the x, y and z axis directions and moments around the x, y and z axes acting between these rigid bodies. A force sensor, which is a first cross sensor in which first and second sensor elements extending in directions of first and second axes that are orthogonal to each other are integrated by intersecting each other in a cross shape at an intermediate portion in each longitudinal direction. And one and the other of the sensor elements extending in the first axis direction and the second axis direction, respectively, are made to intersect with each other in the shape of a cross at each longitudinal intermediate portion, and are integrated with each other. A second cross-shaped sensor arranged in parallel with a third axial direction orthogonal to both the first axis and the second axis, and both longitudinal ends of one of the sensor elements of the first and second cross-shaped sensors. A pair of connecting parts for connecting the parts, and a first cross-shaped section A first connecting portion that connects both ends of the other sensor element in the longitudinal direction to the one rigid body, and connects both ends of the other sensor element in the second cross sensor in the longitudinal direction to the other rigid body. A second connecting portion, and one of the first and second cross-shaped sensors is used for detecting the translational force in the third axis direction and each moment about the first axis and the second axis. The other of the second cross-shaped sensors is a force sensor which is used to detect each translational force in the first and second axis directions and a moment about the third axis. 2. One or the other sensor element in the first or second cross sensor is a parallel plate type sensor element in which slits are formed in an approximately rectangular parallelepiped sensor material, and the first and second tenth sensor elements are provided. A slit penetrating in the second axial direction is formed in the one sensor element of any one of the character-shaped sensors, and a slit penetrating in the first axial direction is formed in the other sensor element, and the first, The force sensor according to claim 1, wherein slits penetrating in the third axis direction are formed in the one and the other sensor elements of the other of the second cross-shaped sensors. 3. The force sensor according to claim 1, wherein the first and second cross-shaped sensors and the connecting portion are integrally formed of the same material. 4. A three-component force sensor that is arranged between two rigid bodies that are objects to be measured and that detects forces acting in the x, y, and z-axis directions between these rigid bodies, which are orthogonal to each other. A cross-shaped sensor in which one and the other sensor elements extending in the first axis direction and the second axis direction, respectively, are integrated by intersecting each other in a cross shape at each longitudinal intermediate portion, and the length of the other sensor element in the cross-shaped sensor. First connecting point end contact between both ends in the direction and the one rigid body
A connecting part and a second connecting part for connecting both ends in the longitudinal direction of one sensor element of the cross sensor and the other rigid body, the first shaft , the second shaft, and the first shaft and the first shaft. Orthogonal to both two axes
The force sensor is characterized in that the origin of the coordinate system consisting of the third axis is set so as to coincide with the connection point of the first connection portion by point contact with the one rigid body. 5. The one and the other sensor elements in the cross-shaped sensor are parallel plate type sensor elements in which slits are formed in an approximately rectangular parallelepiped sensor material, and the one sensor element is arranged in the second axis direction. The force sensor according to claim 4, wherein a slit penetrating therethrough is formed and a slit penetrating in the first axial direction is formed in the other sensor element.