JP2023001368A - force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force sensor that can reduce an outer diameter and can increase the moment component of received force.

SOLUTION: A force sensor 101A includes: a strain body 71 having a light receiving part 71c, a fixed part 71d fixed to the light receiving part 71c, and a beam part 71e connected to the fixed part 71d; and a plurality of strain gauges 1-24. In the beam part 71e, an arm part 71f connected to the light receiving part 71c and a flexure part 71g connected to the fixed part 71d are connected to each other, and six beam parts 71e are formed at the same interval around the axial line of the light receiving part 71c.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to force sensors.

Force sensors are used for advanced control of measuring instruments, industrial robots, and the like. As an example, a configuration has been proposed in which a plurality of strain gauges are provided in a predetermined arrangement on each of the first main surface and the second main surface of the strain body (Patent Document 1: Japanese Patent No. 6047703). Also, a configuration has been proposed in which a plurality of strain gauges are provided in a predetermined arrangement only on the first main surface of the strain body (Patent Document 2: Japanese Patent No. 6378381).

Japanese Patent No. 6047703 Japanese Patent No. 6378381

The strain generating body has a structure in which the receiving force is increased by arranging the beam portion closer to the outer periphery. Therefore, there is a problem that when the outer diameter of the strain generating body is reduced, the moment component of the received force is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a force sensor configured to reduce the outer diameter and increase the moment component of the received force.

As one embodiment, the above problem is solved by means of solution as disclosed below.

A force sensor according to the present invention includes a strain body having a force receiving portion, a fixed portion fixed to the force receiving portion, and a beam portion connected to the fixed portion; The beam portion has an arm portion connected to the force receiving portion and a flexure portion connected to the fixed portion which are connected to each other, and the beam portion extends along the axis of the force receiving portion. 6 are formed at equal intervals around it.

According to this configuration, it is possible to increase the moment component of the received force while maintaining a small outer diameter. In addition, the outer diameter can be made smaller than before while maintaining the magnitude of the moment component of the received force (rated capacity).

As a result, it is possible to easily disperse the stress evenly in each beam portion, and it is expected that the linearity is improved by suppressing the cross-axis interference.

A force sensor according to the present invention includes a strain body having a force receiving portion, a fixed portion fixed to the force receiving portion, and a beam portion connected to the fixed portion; The beam portion has an arm portion connected to the force receiving portion and a flexure portion connected to the fixed portion which are connected to each other, and the beam portion extends along the axis of the force receiving portion. Six strain gauges are formed around the beam portion at equal intervals, half of the strain gauges are arranged on the first main surface of the beam portion, and the second main surface of the beam portion is opposite to the first main surface. The other half of the strain gauges are arranged in the arm portion, and the arm portion has a first arm portion where the strain gauge is arranged and a second arm portion where the strain gauge is not arranged. It is characterized in that they are arranged alternately around the axis of the force receiving portion. With this configuration, it is possible to easily match the output of the strain gauge on the first principal surface with the output of the strain gauge on the second principal surface.

A first arm portion provided with the strain gauge among the arm portions and a second arm portion provided with the strain gauge among the arm portions alternately around the axis of the force receiving portion. are placed in This configuration facilitates further reduction of the outer diameter.

A force sensor according to the present invention includes a strain body having a force receiving portion, a fixed portion fixed to the force receiving portion, and a beam portion connected to the fixed portion; The beam portion has an arm portion connected to the force receiving portion and a flexure portion connected to the fixed portion which are connected to each other, and the beam portion extends along the axis of the force receiving portion. The strain gauges are arranged only on the first main surface of the beam portion, and half of the strain gauges are arranged on the first arm portion of the arm portion. The other half of the strain gauges are arranged on the first flexure portion connected to the first arm portion of the flexure portion, and the strain gauges are arranged on the arm portion. The first arm portion and the second arm portion having no strain gauge are alternately arranged around the axis of the force receiving portion. With this configuration, it is possible to easily arrange the strain gauges with high accuracy by reducing the number of surfaces on which the strain gauges are arranged.

As an example, the strain gauge includes a bridge circuit that detects force components and moment components from four combinations of positions symmetrical to each other with respect to a center line perpendicular to the axis of the first beam portion of the beam portion. arranged to configure With this configuration, it is possible to easily optimize the arrangement of the strain gauges.

As an example, the strain gauges are arranged at two positions along a center line perpendicular to the axis of the first beam part of the beam parts and a center of the second beam part of the beam parts in the direction perpendicular to the axis. It is arranged to form a bridge circuit that detects force and moment components by two combinations of positions along the line. With this configuration, it is possible to easily detect six-axis force components and moment components by reducing the number of strain gauges.

The strain gauges are arranged to form a bridge circuit for detecting force and moment components.

The strain gauges are arranged to form a bridge circuit for detecting force and moment components, and a combination of at least three of the bridge circuits provides an X-axis component, a Y-axis component, and a Y-axis component of the force component. It is preferably arranged to detect an axial component, a Z-axis component, and, of the moment component, a component about the X-axis, a component about the Y-axis and a component about the Z-axis. With this configuration, it is possible to easily measure six-axis force components and moment components with high accuracy.

The strain-generating body is deformed according to a force component in the X-axis direction, a force component in the Y-axis direction, a force component in the Z-axis direction, a moment component about the X-axis, a moment component about the Y-axis, and a moment component about the Z-axis. Consists of possible materials and shapes. The strain-generating body is made of, for example, stainless steel, iron, aluminum, or an alloy thereof.

According to the present invention, it is possible to realize a compact and rationally configured force sensor capable of detecting force and moment with high accuracy.

FIG. 1 is a schematic perspective view showing an example of a force sensor according to the first embodiment of the invention. 2A is a plan view of the force sensor shown in FIG. 1, FIG. 2B is a front view of the force sensor, and FIG. 2C is a bottom view of the force sensor. FIG. 3 is an example of a bridge circuit of the force sensor shown in FIG. FIG. 4 is an output signal table of the bridge circuit shown in FIG. FIG. 5 is a schematic plan view showing an example of a force sensor according to the second embodiment of the invention. FIG. 6 is an example of a bridge circuit of the force sensor shown in FIG. FIG. 7 is an output signal table of the bridge circuit shown in FIG.

(First embodiment)
A first embodiment of the present invention will be described in detail below with reference to the drawings. The force sensor 101A of the present embodiment has force components Fx, Fy, and Fz in the three-axis orthogonal coordinate system (X-axis, Y-axis, and Z-axis) in a three-dimensional space, moment components Mx about the three axes, It is a 6-axis force sensor capable of simultaneously detecting a total of 6 components My and Mz. The force sensor 101A of the present embodiment is an example of a configuration in which six beam portions 71e indicated by dashed lines are provided at rotationally symmetrical positions about the central axis P1. FIG. 1 is a schematic perspective view showing an example of a force sensor 101A according to this embodiment (a signal processing unit and wiring are not shown). In addition, in all drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and repeated description thereof may be omitted.

As shown in FIGS. 1 and 2A to 2C, the force sensor 101A includes a force receiving portion 71c, a fixed portion 71d fixed to the force receiving portion 71c, and a beam portion 71e connected to the fixed portion 71d. and a plurality of strain gauges 1-24. Here, for example, strain gauges 1 and 3 each detect bending strain, and for example, strain gauges 13 and 14 each detect shear strain. In the beam portion 71e, an arm portion 71f connected to the force receiving portion 71c and a flexure portion 71g connected to the fixed portion 71d are connected to each other. are formed. In this example, half of the plurality of strain gauges 1-24 are arranged on the first main surface 71a, and the other half of the plurality of strain gauges 1-24 are arranged on the second main surface 71b. It is A plurality of strain gauges 1 to 24 are all arranged on the arm portion 71f. In this example, a screw hole 71i is formed for fixing to the object to be measured, and a through hole 71h is formed for fixing to the measurement base.

As an example, the strain body 71 is manufactured by forming a through hole or the like in a springy material such as an aluminum alloy, alloy steel, or stainless steel using an NC machine. As an example, the strain body 71 is manufactured by subjecting a plate-shaped body having a circular outer shape to cutting, laser processing, electrical discharge machining, or a combination of these processes.

As an example, the strain gauges 1 to 24 may have a configuration in which a wiring pattern of a metal thin film of a Cu—Ni alloy or an Ni—Cr alloy is covered with a polyimide film or an epoxy film, and a configuration using a semiconductor thin film. may be As an example, there is a case where a strain gauge made of a metal thin film is directly formed using a sputtering method or a vacuum deposition method. As an example, the strain gauges 1 to 24 are made of sputtered films of the same material or deposited films of the same material. As a result, symmetry can be maintained, productivity is improved, and a configuration in which manufacturing variations are suppressed as much as possible can be achieved. As an example, the strain gauges 1 to 24 can be configured to be collectively formed simultaneously. As a result, the strain gauges 1 to 24 can have a uniform resistance value. It should be noted that the strain gauges 1 to 24 are not limited to the configuration described above, and may be configured by adhering each of the strain gauges 1 to 24 in the shape of a plate, a sheet, or a film. The strain gauges 1 to 24 are arranged so that four combinations of positions symmetrical to each other with respect to the center line in the direction perpendicular to the axis of the arm portion 71f constitute a bridge circuit for detecting a force component in a predetermined direction. It is Further, the first arm portion 71f1 of the arm portion 71f having the strain gauge and the second arm portion 71f2 having no strain gauge of the arm portion 71f move around the axis of the force receiving portion 71c. are arranged alternately.

FIG. 3 shows bridge circuits C6A1, C6A2, C6A3, C6A4, C6A5 and C6A6 which are composed of a plurality of strain gauges 1-24. It is configured to apply a voltage to each bridge circuit and take out an output signal Vo. A plurality of strain gauges 1 to 24 are sufficient to obtain the output signals necessary for detecting the six-axis force and moment components in the strain body 71 having a Y beam.

FIG. 4 is an output signal table of the bridge circuits C6A1, C6A2, C6A3, C6A4, C6A5 and C6A6. For each strain gauge, when the resistance value of the strain gauge forming each bridge increases when a force is applied in each direction, it is defined as "+", and when the resistance value of the strain gauge decreases, it is defined as "-". and "0" when the resistance value of the strain gauge does not change or when the amount of change in the resistance value of the strain gauge is small and can be regarded as not changing. Each output signal is "1" when an unbalanced output occurs in each bridge, and "0" when an unbalanced output does not occur in each bridge.

According to this embodiment, the moment component of the received force can be increased by the configuration in which six beam portions are formed at equal intervals around the axis and the stress is dispersed in each beam portion. As an example, the outer diameter can be 120 [mm] or less.

(Second embodiment)
Continuing on, the second embodiment of the present invention will be described with a focus on the differences from the above-described first embodiment. As shown in FIG. 5, the force sensor 101B of the present embodiment is an example of a configuration in which six beam portions are provided at rotationally symmetrical positions in a plan view. A first arm portion having the strain gauge and a second arm portion having no strain gauge are alternately arranged around the axis of the force receiving portion. and the strain gauges 1 to 24 are arranged only on the first main surface of the beam portion. Here, for example, the strain gauges 1 to 4 are configured so that a bridge circuit for detecting a force component in a predetermined direction is formed by a combination of four positions symmetrical to each other with respect to the center line in the direction perpendicular to the axis of the arm portion. are placed in each. Further, for example, the strain gauges 5 to 8 are configured so that a bridge circuit for detecting a force component in a predetermined direction is formed by a combination of four positions symmetrical to each other with respect to the center line perpendicular to the axis of the flexure portion. are arranged respectively. A first arm portion 72f1 having a strain gauge out of the arm portions 72f and a second arm portion 72f2 having no strain gauge out of the arm portions 72f move around the axis of the force receiving portion 72c. are arranged alternately.

FIG. 6 shows bridge circuits C6B1, C6B2, C6B3, C6B4, C6B5 and C6B6 which are composed of a plurality of strain gauges 1-24. A plurality of strain gauges 1 to 24 are sufficient to obtain the output signals required to detect the six-axis force and moment components. FIG. 7 is an output signal table of the bridge circuits C6B1, C6B2, C6B3, C6B4, C6B5 and C6B6.

According to this embodiment, since the strain gauges 1 to 24 are arranged only on the first main surface of the beam portion, the number of surfaces on which the strain gauges 1 to 24 are arranged is reduced, and the strain gauges are arranged with high accuracy. can be easily placed in

1 to 24 strain gauge 71 strain generating body 71a first main surface 71b second main surface 71c force receiving portion 71d fixing portion 71e beam portion 71f arm portion 71g flexure portion 71h through hole 71i screw hole 72 strain generating body 72a first main surface 72b second main surface 72c force receiving portion 72d fixing portion 72e beam portion 72f arm portion 72g flexure portion 72h through hole 72i screw hole 101A, 101B force sense Sensor C6A1, C6A2, C6A3, C6A4, C6A5, C6A6 Bridge circuit C6B1, C6B2, C6B3, C6B4, C6B5, C6B6 Bridge circuit C8A1, C8A2, C8A3, C8A4, C8A5, C8A6 Bridge circuit P1 Central axis (axis)

Claims (3)

a strain body having a force receiving portion, a fixed portion fixed to the force receiving portion, and a beam portion connected to the fixed portion; and a plurality of strain gauges arranged on the beam portion, In the beam portion, an arm portion connected to the force receiving portion and a flexure portion connected to the fixed portion are connected to each other, and six beam portions are formed at equal intervals around the axis of the force receiving portion. and
The strain gauge is arranged only on the first main surface of the beam portion,
Half of the strain gauges are arranged on the first arm portion of the arm portion, and the other half of the strain gauges are arranged on the first flexure portion of the flexure portion connected to the first arm portion. has been
In the arm portion, the first arm portion provided with the strain gauge and the second arm portion not provided with the strain gauge are alternately provided around the axis of the force receiving portion. A force sensor characterized by: a strain body having a force receiving portion, a fixed portion fixed to the force receiving portion, and a beam portion connected to the fixed portion; and a plurality of strain gauges arranged on the beam portion, In the beam portion, an arm portion connected to the force receiving portion and a flexure portion connected to the fixed portion are connected to each other, and six beam portions are formed at equal intervals around the axis of the force receiving portion. and
Half of the strain gauges are arranged on a first principal surface of the beam portion, and the other half of the strain gauges are arranged on a second principal surface of the beam portion opposite to the first principal surface. and
In the arm portion, a first arm portion provided with the strain gauge and a second arm portion provided with no strain gauge are alternately arranged around the axis of the force receiving portion. A force sensor characterized by: The strain gauges are arranged to form a bridge circuit for detecting force and moment components, and a combination of at least three of the bridge circuits provides an X-axis component, a Y-axis component, and a Y-axis component of the force component. It is arranged to detect an axial component, a Z-axis component, and, of the moment components, a component about the X-axis, a component about the Y-axis, and a component about the Z-axis. The force sensor according to claim 1 or 2.

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