JPH1078360A - Multiaxial force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate the output matching of axial force and moment with a relatively inexpensive structure by mutually differing the spring constant between an axial force detecting distortion generating part and a moment detecting distortion generating part. SOLUTION: The spring constant is mutually different between an axial force detecting distortion generating part and a moment detecting distortion generating part, whereby the mechanical load-distortion characteristic for each distortion generating part is regulated to mutually balance the output dynamic ranges of each directional distortion. For example, the sectional areas of the part for sticking axial force detecting strain gauges 6a-6d and the part of sticking moment detecting strain gauges 7a-7d in one beam 4 are mutually differed, or a slit 5 is provided on the base of the beam 4 to form the axial force detecting strain generating part. Namely, both X, Y beams 3, 4 are made more slender in the center parts than in both end parts. The base parts to a frame part 2 of the beams 3, 4 are thinned by the slits 5 in order to allow the axial displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-axial force sensor using a strain gauge capable of detecting axial forces and moments in a plurality of directions simultaneously or individually.

[0002]

2. Description of the Related Art As one of force sensors, a set of four resistance wire strain gauges attached to a strain generating section is bridge-connected, and the strain of the strain generating section according to the force is detected as a change in electric resistance. Is known.

Now, three axes X, Y, and Z orthogonal to each other are described.
As a multi-axial force sensor for detecting the axial forces Xf, Yf, Zf along the axis and the moments Xm, Ym, Zm around these axes simultaneously or individually, 2. Description of the Related Art There is known a structure in which two beams connecting between two beams are made orthogonal to each other, and a force input to an intersection of the two beams is detected by a strain gauge attached to each beam. In this case, for example, the axial force Xf along the X beam is detected from the bending strain in the horizontal plane of the Y beam orthogonal to the X beam, and the moment Xm around the X axis is detected from the bending strain in the vertical plane of the Y beam. It is supposed to. Similarly, the axial force Yf along the Y beam is detected from the bending strain in the horizontal plane of the X beam, and the moment Ym about the Y axis is detected from the bending strain in the vertical plane of the X beam. . The axial force Zf in the Z-axis direction is detected from the bending strain in the vertical plane of the X beam or the Y beam, and the moment Zm around the Z axis is detected from the bending strain in the horizontal plane of the X beam or the Y beam. I have.

[0004]

However, if the beam constituting the strain generating portion has a uniform cross-sectional shape in the axial direction, a difference occurs in the dynamic range between the strain output by the axial force and the strain output by the moment. When passing through amplifiers having a common amplification degree, the scales of the two may become uneven.

In order to prevent such inconvenience, it is necessary to match the strain output between the axial force and the moment. For this purpose, the gain of the amplifier is changed or any of the strain gauges connected in a bridge is used. It is necessary to interpose a resistor for output matching on the side of the circuit, but in any case, the circuit configuration and the specifications of the amplifier cannot be unified for all the strain gauges, so that the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been devised to solve such a disadvantage of the prior art, and its main purpose is to provide an output matching between an axial force and a moment with a relatively inexpensive configuration. It is an object of the present invention to provide a multi-axis type force sensor which can be used.

[0007]

In order to achieve the above object, the present invention provides a multi-axis strain gauge using a strain gauge capable of detecting axial forces and moments in a plurality of directions simultaneously or individually. In the die-type force sensor, the mechanical load-strain characteristics of each strain generating part are adjusted by making the spring constants of the axial force detecting strain generating part and the moment detecting strain generating part different from each other. Thus, the dynamic range of the distortion output in each direction is balanced. As a specific form, the cross-sectional area of the portion where the axial force detection strain gauge is attached to the one beam and the portion where the moment detection strain gauge is attached may be different from each other, or may be perpendicular to the beam at the base of the beam. Orientation slit is provided and this is used as a strain generating part for detecting the axial force, or the beam itself is divided into a plurality of portions having different cross-sectional areas along the axial direction by the slit, and the load is substantially applied to one beam. -It is possible to provide a plurality of distortion generating units having different distortion characteristics from each other.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a six-axis type force sensor configured according to the present invention. This force sensor 1
It is formed by cutting out from a block of elastic material, and is formed of a square frame portion 2, and X beams 3 and Y beams 4 which connect the mutually facing inner surfaces of four sides of the frame portion 2 and which are orthogonal to each other. And two beams.

Both the X and Y beams 3 and 4 are narrower at the center than at both ends. In addition, the base of the beams 3 and 4 with respect to the frame 2 is thinned by a slit 5 along a vertical plane in order to allow displacement of the beams 3 and 4 in the axial direction.

The axis of the X beam 3 is the X axis, and the axis of the Y beam 4 is the Y axis.
Assuming that a virtual axis passing through the intersection of the axis and the X and Y axes and orthogonal to both axes is the Z axis, an input rod (not shown) and a frame that receive a load on the Z axis are fixed.

Here, the plane on which both the X and Y axes extend is a horizontal plane,
If the plane on which the Z-axis extends is defined as a vertical plane, the axial force Xf in the X-axis direction is detected by bending strain of the Y beam 4 in the horizontal plane, and X
The moment Xm about the axis is detected by bending strain in the vertical plane of the Y beam 4. The moment Zm about the Z axis is Y
It is detected by the bending strain of the beam 4 in the horizontal plane. For this reason, Y
Four strain gauges 6a to 6d for detecting an axial force Xf in the X-axis direction are provided on both vertical surfaces of the small-diameter portion 4s of the beam 4, and a Z-axis is provided on both vertical surfaces of the large-diameter portion 4b of the Y beam 4. Four strain gauges 7a to 7d for detecting the moment Zm and four strain gauges 8a to 8d for detecting the X-axis moment Xm are provided on both horizontal surfaces of the large-diameter portion 4b of the Y beam 4 at point-symmetric positions. It is provided in.

Similarly, the axial force Yf in the Y-axis direction is the bending strain of the X beam 3 in the horizontal plane, and the moment Ym about the Y axis is the bending strain of the X beam 3 in the vertical plane. And Z
The axial force Zf in the axial direction is detected by bending strain in the vertical plane of the X beam 3. Therefore, the small-diameter portion 3 of the X beam 3
The four strain gauges 9a to 9d for detecting the axial force Yf in the Y-axis direction are provided on both vertical planes of s, and the Y-axis moment Ym is detected for both horizontal planes of the large-diameter portion 3b of the X beam 3. The three strain gauges 10a to 10d and the small diameter portion 3s of the X beam 3
On both horizontal planes, four strain gauges 11a to 11d for detecting an axial force Zf in the Z-axis direction are provided at point-symmetric positions with respect to each other.

Each of these four sets of strain gauges is bridge-connected. In FIG. 1, reference numerals in parentheses indicate strain gauges attached to opposite surfaces, respectively.

If the beams are made of the same material, the smaller the cross-sectional area, the greater the amount of strain with respect to the load. Therefore, the dynamic range of the strain output of the axial force and the moment is made equal to each other by changing the cross-sectional area according to the part where the strain gauge for detecting the axial force and the moment is attached and optimally setting the spring constant of the beam. Can be.

FIG. 2 shows another embodiment of the present invention. In the present embodiment, a slit 5 is provided at the base of both beams 23 and 24 with respect to the frame 2 so as to be orthogonal to the beam, and on both sides of the base of the beam in the thin portion 12 formed by this. , X-axis force detection strain gauges 6a to 6d and Y-axis force detection strain gauges 9a to 9d are attached. In this case, the axial forces Xf and Yf in both the X and Y axial directions are detected from the bending of the thin portion 12.

On the other hand, the Y beam 24 is
, Two portions 24u and 24 having different cross-sectional areas from each other.
1 in the vertical direction. Four strain gauges 11a to 11d for detecting the axial force Zf in the Z-axis direction are provided on both horizontal surfaces of the upper portion 24u of these two portions, and the X-axis is provided on both horizontal portions of the lower portion 24l. Four strain gauges 8a to 8d for detecting the moment Xm are provided.

The X beam 23 is formed by removing the upper portion from the slit 13 of the Y beam 24 and has four strain gauges 10a for detecting the Y-axis moment Ym on both horizontal planes.
Four strain gauges 7a to 7d for detecting the Z-axis moment Zm are provided on both vertical planes.

Thus, substantially one beam is provided with two strain generating portions having mutually different load-strain characteristics.

In this embodiment, if it is difficult to attach a strain gauge to the inner surface of the slit 13, first, only the lower part of the shape such as the X beam 23 is formed to form the strain gauge. After the attachment, the upper portion to which the strain gauge is attached in advance may be welded with a gap serving as a slit.

The positions of the strain gauges for detecting each axial force and each axial moment are not limited to the positions shown in the above-described embodiment, but may be changed so that desired load-strain characteristics can be obtained. It goes without saying that they can be appropriately selected and combined.

[0022]

As described above, according to the present invention, the mechanical load-strain characteristic of the strain generating section is adjusted to balance the dynamic range of the strain output in each direction. Can be unified for all axes, so that the production cost does not increase.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a six-axis type force detector according to the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 6-axis type force sensor 2 Frame part 3.23 X beam 4.24 Y beam 5 Vertical slit 6 Xf strain gauge 7 Zm strain gauge 8 Xm strain gauge 9 Yf strain gauge 10 Ym strain gauge 11 Zf Strain gauge 12 Thin part 13 Horizontal slit

Claims (4)

[Claims] 1. A strain generating part comprising two beams fixed at both ends and orthogonal to each other and fixed to a frame to simultaneously or individually detect axial forces and moments in a plurality of directions, and a strain provided on the strain generating part. What is claimed is: 1. A multi-axial force sensor having a gauge, wherein a spring constant of an axial force detecting strain generating portion and a moment detecting strain generating portion are different from each other. 2. The cross-sectional area of a portion of one beam to which an axial force detecting strain gauge is attached and a portion to which a moment detecting strain gauge is attached are different from each other. Multi-axis type force sensor. 3. The multi-axial force sensor according to claim 1, wherein a slit in a direction perpendicular to the beam is provided at a base of the beam to form a strain generating portion for detecting an axial force. 4. The beam itself is formed by a slit along an axial direction so as to be divided into a plurality of portions having different cross-sectional areas, and a plurality of strain generating portions having substantially different load-strain characteristics are provided on substantially one beam. The multi-axial force sensor according to claim 1, wherein: