JPH0617839B2 - Maybe force detector and maybe force detector using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention is, for example, to conduct an experiment in a wind tunnel for the influence of air (for example, air resistance) received by a traveling vehicle, or to construct a relatively large structure such as a parabolic antenna. The present invention relates to a multi-component force detector suitable for detecting each component force and a rotation moment, which are basic data when measuring an influence on a wind force, and a multi-component force detection device using the same.

(b) Prior art When a force acts on an object, the force is a force in the X coordinate axis direction, a force in the Y coordinate axis direction, and a Z coordinate axis (hereinafter, X, Y, and Z coordinate axes are “X axis” and “Y axis”). It is considered that the forces in the directions "," and "Z axis" are combined. Therefore, it is possible to know the mode of the force acting on the object by detecting the three component forces of the force acting on the object in the X-axis direction, the Y-axis direction, and the Z-direction.

Further, by detecting the moments of the rotations of the three components about the X axis, the Y axis, and the Z axis respectively, it is possible to know the mode of the rotation moment acting on the object.

Then, of the above-mentioned three-component force and three-component rotational moment, the required one is measured according to its purpose.

As a conventional force detecting device, for example, Japanese Utility Model Publication No. 47-5
As disclosed in Japanese Patent Publication No. 53-53, an object to be measured which should detect the above-mentioned three-component force and three-component rotational moment is fixed to a movable table, and the lower surface side and the side surface side of the movable table are independent of each other. There is a configuration in which a plurality of displacement force detectors are set and desired component data and rotational moment data are obtained based on the data obtained from each of the displacement force detectors.

However, in such a force detecting device,
Since the transmission of force to the displacement force detector is done via the support movably attached to the movable table, the overall shape of the force detector is likely to become large and thick, and installation work is also required. It is very complicated, and there is a problem that if the movable table is not made thick, a large measurement error due to bending is mixed.

On the other hand, JP-A-58-13 proposed by the applicant of the present invention has been made to solve the above-mentioned drawbacks of the conventional example.
There is a walking analysis force plate shown in No. 8439. This gait analysis force plate supports the four corners of a walking platform on a fixed platform via three-component force detectors, and the three-component force detector is arranged between the upper and lower connecting ends in the Z-axis direction (walking). The first and third detection leg portions along the platform (up and down direction) and the second detection leg portion along the X-axis direction (left and right or front and back direction of the walking platform) are integrally connected to each other, and The second and third detection legs are respectively provided with the X-axis direction, Z-axis direction, and Y-axis direction component force detection extensions that extend in the ZX plane, the XY plane, and the YZ plane, respectively. A strain gauge is formed, and strain gauges are attached to the first, second, and third strain transducers, and the upper connection end of the three-component force detector and the walking platform have elasticity in the X-axis direction, Y. Axial direction, Z
It is configured to be connected by a transmission rod along the axial direction.

In this latter conventional example, the shape of the entire device can be downsized, and the walking platform can also be made thin to some extent, but it is not possible to make it thin enough to significantly reduce the weight because it will deteriorate the interference characteristics. .

If the loading platform is thick, for example, the natural frequency of the vibrating string formed by the weight of the object to be measured and the loading platform will decrease, and therefore the response frequency band will become narrow and the weight will be heavy. As a result, it becomes difficult to carry out work such as transportation, installation, and adjustment, and the cost also rises.Furthermore, this type of force detector is often inserted in the force transmission system of structures and machinery, In particular, it causes inconvenience such as installation being impossible due to dimensional restrictions.

(c) Object The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-component force detector that is small in size, light in weight, inexpensive, and yet capable of accurately detecting multi-component force. Another object of the present invention is to provide a multi-component force detecting device that can realize a significant reduction in weight by thinning the loading platform without particularly deteriorating the interference characteristics by using this multi-component force detector.

(d) Structure In order to achieve the above-mentioned object, the first invention (the invention according to claim 1) is such that strain gauges are attached to a plurality of locations of a flexure element that elastically deforms when an external force is applied. In the force detector, which is obtained by separating a plurality of electric signals corresponding to external force applied from a plurality of directions by the strain gauges, an external force introducing portion having a large rigidity formed on one end side of the columnar strain generating body. A columnar strain generating portion whose one end side is connected to the external force introducing portion, and at least four beams which extend in a direction orthogonal to the axis of the columnar strain generating portion and one end side of which is connected to the other end side of the columnar strain generating portion. And a pedestal portion having high rigidity connected to the other end of the beam, and a surface along the axis of the columnar strain generating portion, which is attached to each of the surfaces orthogonal to each other, in the X-axis direction and the Y-axis direction. First strain gauge that detects each component force And a second strain gauge, and a third strain gauge attached to each of the beams for detecting a component force in the Z-axis direction, the pedestal portion is fixed, and a force is applied to the external force introducing portion from an arbitrary direction. When applied, the first, second, and third strain gauges are configured to separately obtain electric signals corresponding to the forces of the axial components of the X axis, the Y axis, and the Z axis, respectively. A second aspect of the invention (the invention according to the second aspect of the claim) is characterized in that an external force introducing portion having large rigidity is formed on one end side, and the columnar straining portion is formed in the external force introducing portion. Are connected to each other, and at least four beams extending in a direction orthogonal to the axis of the columnar strain generating portion are connected to the other end side of the columnar straining portion. The flexure element connected to each other and the surface along the axis of the columnar flexure portion, which are directly connected to each other. A first strain gauge and a second strain gauge attached to each of the surfaces to be detected to detect component forces in the X-axis direction and the Y-axis direction, respectively, and a first strain gauge to detect component force in the Z-axis direction attached to the beam. A plurality of multi-component force detectors each having a strain gauge of 3, a base fixing each pedestal of the plurality of multi-component force detectors, and each external force introduction part of the multi-component force detectors in a point contact state. A flat plate that is connected to the external force introducing portion via a connecting member that transmits a force acting in a direction orthogonal to the axial direction of the columnar strain generating portion to the load introducing portion when contacted, and is arranged to face the base in a parallel state. It is characterized in that it is constituted by a flat loading plate and a flat plate-shaped intermediate plate which is arranged to face the loading plate at a predetermined interval and which connects each of the external force introducing portions of the multi-component force detector.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a perspective view showing a schematic configuration of the present invention (including the first and second inventions).

In the figure, 1 is a multi-component force detector according to the first invention, and the main configuration of the multi-component force detection device according to the second invention is
The four above-mentioned multi-component force detectors 1, a base 2 for fixing the pedestals of the four multi-component force detectors 1, and a flat plate-like structure for connecting the respective external force introducing portions of the multi-component force detector 1 It comprises an intermediate plate 3 and a loading table 4 which is in point contact with the external force introducing portions of each of these four multi-component force detectors 1 and which is connected via a connecting member 5.

Between the base 2 and the loading table 4, there is provided a clamp mechanism 6 that functions as a stopper when an excessive force is applied during movement of the force detection device or during measurement.

First, the structure of the multi-component force detector 1 will be described with reference to FIGS. 1 to 3.

FIG. 1 is a partially cutaway front view showing the structure of a main part of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 3, and FIG. 3 is a sectional view taken along the line BB. It is a figure.

In these figures, the multi-component force detector 1 has a substantially columnar shape, and an external force introducing portion 1a having increased rigidity is formed at one end portion (upper end portion in FIG. 1) of the external force introducing portion 1a. To form a columnar strained portion 1b, one end of which is connected to the other end portion (lower end portion in FIG. 1) of the columnar strained portion 1b and which extends radially in a direction orthogonal to the axis of the columnar strained portion 1b. The four beams 1c are formed, and the four beams 1c are further formed.
A pedestal portion 1d having a large rigidity and connected to the other end of the pedestal is formed.

As shown in FIG. 2, the columnar strain generating portion 1b is formed in a columnar shape having a square cross section, and a portion for detecting a component force in the X-axis direction is formed at a portion near the lower end of the surface along the axial direction. The strain gauges 11 and 11 as the strain gauges of 1 are bonded, vapor-deposited,
They are attached by fusion or other means, and the strain gauges 11 and 9 are attached to the surface on which the strain gauges 11 and 11 are attached, respectively.
Strain gauges 12, 12 as second strain gauges for detecting a component force in the Y-axis direction are attached to the surface forming 0 ° by the same means. As described above, one end of the four beams 1c is integrally connected to the lower end of the columnar strained portion 1b, and the other end of the beam 1c extending in the radial direction is
An annular pedestal portion 1d is integrally connected. The side surface of the beam 1c, that is, the surface along the axis of the columnar strained portion 1b, has a shear axis having a sensitive axis (principal axis) in a direction deviated from the longitudinal direction of the beam 1c by + 45 ° and -45 °, respectively. Strain gauges 13 to 16 that are of the strain detection type and that are third strain gauges for detecting the Z-axis direction force are attached. The first, second and third strain gauges 11,
12 and 13 to 16 each have a well-known Wheatstone bridge configuration, and the Wheatstone bridge configured by the first strain gauge 11 has the columnar strain generating portion 1
It is sensitive to the force in the X-axis direction of b, that is, the lateral direction in FIG. 1, outputs an electric signal corresponding to the force, and is insensitive to the force in the other directions. The Wheatstone bridge constituted by the second strain gauge 12 is sensitive only to the force in the Y-axis direction of the columnar strain generating portion 1b, that is, the direction orthogonal to the paper surface in FIG. 1, and outputs an electric signal corresponding to the force. However, it is insensitive to forces in other directions. Third strain gauge 13, 14, 15, 1
The Wheatstone bridge constituted by 6 is sensitive only to the force of the columnar straining portion 1b in the Z-axis direction, that is, the vertical direction in FIG. 1, and outputs electric signals corresponding to the force and the rotational moment, respectively.

When the multi-component force detector 1 having such a configuration is used alone, the pedestal portion 1d is fixed to the fixed base by means such as screwing, and the object to be measured is attached to the external force introducing portion 1a by screwing or the like. It may be firmly fixed by means. Then, the external force received by the object to be measured from the fluid or the like is separated into at least a three-component force of the X-axis, the Y-axis, and the Z-axis and a rotational moment about the Z-axis by the multi-component force detector 1, and each is converted into an electric signal. It can be detected.

Next, an embodiment of the multi-component force detecting device constructed by using four multi-component force detectors 1 constructed as described above will be described in detail.

Possibly the pedestal portion 1d of the force detector 1 is made of a lightweight material such as an aluminum alloy and is attached to a base 2 formed in a thick plate shape.
It is fixed by a fixing screw 18 inserted in the screw through hole 17.

On the other hand, the flange portion 19 is provided near the upper end of the columnar straining portion 1b.
The intermediate plate 3 formed in a relatively thin plate shape is brought into contact with the upper surface of the flange portion 19 in a state in which the external force introduction 1a is projected from the circular hole 20, and the fixing screw 21 is formed. Is fixed by. Further, an abutting portion 22 having a substantially hemispherical projecting surface is formed on the upper portion of the columnar strain generating portion 1b and fixed by a fixing screw 23 with an annular diaphragm 24 interposed therebetween. There is. A thick-walled annular attachment member 25 is integrally or adjacently connected to the outer peripheral portion of the diaphragm 24. The mounting member 25 is firmly fixed to the above-described loading table 4 by a mounting screw (not shown).

Here, the external force introducing portion 1a of the force detector 1 and the loading table 4 serve to connect the X-axis and Y-axis directions in a restraining relationship with each other and with the Z-axis direction not restraining each other. The diaphragm 24, the mounting member 25, and the like described above are referred to as “connecting members”.
Shall be called.

Further, the tip of the contact portion 22 is in contact with the receiving member 26 having a relatively high rigidity, which is attached to the recess formed in a part of the loading table 4. The receiving member 26 is fixed to the loading table 4 by a fixing screw 28 that is inserted into a screw hole 27 formed in the loading table 4. As described above, the receiving member 26 is provided because the loading platform 4 is formed of a soft aluminum alloy material for weight reduction, and when the loading platform 4 is brought into direct contact with the load introducing portion 1a, wear progresses rapidly, and detection is performed. This is because the accuracy is lowered. The strain gauges 11 to 1 described above
The bellows-shaped cover member 29 has its upper and lower ends welded to the upper and lower ends of the columnar strained portion 1b in order to prevent the entry of foreign matter such as dust, etc. In order to make each of the strain gauges 13 to 16 attached to the beam 1c similarly moisture-resistant and to prevent foreign matter such as dust from entering, two bellows-shaped cover members are attached. Both inner diameter portions of 30 are welded to the base portion of the columnar strain generating portion 1b, and both outer diameter portions thereof are attached to the pedestal portion 1d in a welded state.

On the other hand, two clamp mechanisms 6 are provided at each of the four corners of the force detection device. That is, the support member 7 forming the clamp mechanism 6 is fixed to the lower surface of the loading table 4, and the support member 8 is also fixed to a portion of the base 2 facing the support member 7. A female screw is formed on the support member 8, and a bolt 9a is embedded in the female screw, and the base portion thereof is fixed by a nut 9b. Further, a nut 9c is screwed into an intermediate portion of the bolt 9a, and a truncated cone-shaped cylindrical body 10 is inserted into an upper portion of the nut 9c. The upper portion of the cylindrical body 10 is in contact with the receiving hole portion formed in the support member 7. A nut 9d is screwed onto the upper end of the bolt 9a.

With such a clamp mechanism, when the force detection device is moved or the object to be measured is attached, the base 2 and the loading table 4 are clamped to each other so that the force detector 1 may receive an excessive force. It is provided so as not to be loaded and to function as a stopper that prevents the base 2 and the loading table 4 from approaching or separating from each other by a certain amount or more.
For example, assuming that the state shown in FIG. 1 is set to the clamped state, the nut 9c of each clamp mechanism 6 is loosened and moved downward by a predetermined amount in the figure to make the state detectable. At the same time, the nut 9d may be loosened and moved upward. On the contrary, when the nuts 9c and 9d are tightened in the relationship shown in FIG. 1, the clamped state can be obtained. If such a clamp state is set, even if the loading table 4 is lifted using the unillustrated eye bolts or the like fixed to the loading table 4 and the entire force detection device is moved, the force detection device 1 is excessively large. Since no great stress is applied, a situation in which the device is broken is prevented.

If the distance between the cylindrical body 10 and the support member 7 is set to the displacement amount when the maximum load allowed by the force detector 1 is set, a safety measure for the force detector 1 is taken. It will be.

Next, the operation of the thus configured multi-component force detecting device according to the present invention will be described.

A load, a force, a moment, etc. are applied to the loading platform 4 from an object to be measured placed or fixed on the loading platform 4. For example, the acting direction of the force is shown in FIG. The force Fx acts on the loading platform 4 only in the left-right direction. By this force Px, the loading platform 4 is displaced in the left-right direction with respect to the base 2, and this displacement is transmitted to the load introducing portion 1a via the connecting member 5, and the load introducing portion 1a is displaced in the left-right direction. . Then, the strain gauges 11 and 11 attached to the opposite surfaces of the columnar strain generating portion 1b which are deviated from each other by 180 °.
One shrinks and reduces its resistance, the other stretches and increases its resistance. The force Fx can be detected based on the electric signal obtained from the output of the Wheatstone bridge circuit (not shown) constituted by the strain gauge 11 that changes the resistance. At this time, strain gauge 1
Since Nos. 2 and 12 are attached to the bending neutral axis, respectively, substantially no output is produced.

Further, at this time, the rotation moment Mx about the axis of the force Fx can be obtained by calculating the sum of the outputs of the component forces in the Z-axis direction of the four multi-component force detectors 1 shown in FIG. it can.

On the other hand, when the displacement of the loading table 4 is in the Y-axis direction, that is, in the vertical direction shown in FIG. 5, one of the strain gauges 12, 12 contracts as the columnar strain-generating portion 1b displaces, as described above. The other stretches. Therefore, the force Fy can be detected by detecting each resistance change of the strain gauge 12 which makes such a change with a Wheatstone bridge circuit or the like not shown.
At this time, the displacement of the strain gauges 11, 11 does not substantially occur for the same reason as described above.

Further, at this time, the rotational moment My about the axis of the force Fy can be obtained by calculating the sum of the output of the component forces in the Z-axis direction of the four multi-component force detectors 1 shown in FIG. it can.

In addition, when a force having components in both the left-right direction and the vertical direction shown in FIG.
Wheatstone bridge including strain gauge 11 of
The Wheatstone bridge including the second strain gauge 12 can separately detect the component force in the X-axis direction and the component force in the Y-axis direction.

On the other hand, when a force Fz in the Z-axis direction is applied to the loading table 4, substantially the same shear strain occurs in the four beams 1c. This shear strain is detected by the third strain gauges 13 to 16 attached to each beam 1c, and an electric signal corresponding to the force Fz is generated by one or a plurality of Wheatstone bridges constituted by these strain gauges 13 to 16. Can be obtained. At this time, the first strain gauge 1
1, 11 and the second strain gauges 12, 12 are also displaced, but the strain gauges 11 and 11 (or 12) attached to the mutually opposite surfaces (the surfaces displaced by 180 °) of the columnar strain generating portion 1b.
And 12) do not appear as an output when they generate the same strain, because they are electrically canceled by the Wheatstone bridge.

Further, the rotational moment Mz about the Z axis can be obtained by calculating the output sum of the component forces in the X axis direction and the output sum of the component forces in the Y axis direction of the four multi-component force detectors 1. it can.

The outputs obtained from the first, second and third strain gauges (Wheatstone bridge) of the four force detectors 1 obtained as described above are appropriately amplified, for example, via a dynamic strain gauge. Predetermined arithmetic processing is performed by the arithmetic circuit, and the component force and the rotational moment that act on the object to be measured that is mounted on the mounting table 4 and is almost fixed are obtained.

Here, the operation of the intermediate plate 3 will be described.

As in this embodiment, since the loading table 4 is made thin and is made of an aluminum material, without the intermediate plate 3, the force (or load) in the Z-axis direction from the object to be measured is placed on the loading table 4. Is loaded, the loading table 4 is largely bent, and a force for attracting the adjacent force detector 1 acts,
The columnar strained portions 1b are tilted toward each other. Therefore, although the force acts in the Z-axis direction, an output as a component force in the X-axis direction or the Y-axis direction appears, which causes a large measurement error. As shown in FIG. 1, such a problem is to arrange the intermediate plate 3 so as to connect the external force introducing portions 1b of the respective force detectors 1 at regular intervals from the loading table 4. Will be solved. This is because the loading table 4 bends so as to bulge downward due to the application of an external force from the Z-axis direction, and the intermediate plate 3 resists the force that tends to draw the detectors 1 adjacent to each other. . Despite the improved interference characteristics as described above, the total thickness of the loading table 4 and the intermediate plate 3 can be made considerably thinner than the conventional loading table 4 alone, resulting in weight reduction. It can make a big contribution.

Further, in the present embodiment, the loading table 4 is configured to be in point contact with each of the external force introducing portions 1b of the four multi-component force detectors 1 and to be connected via the connecting member 5, so that Even if the external force (load) is intensively applied to the loading table 4 and the loading table 4 bends, the contact point of the upper end of the columnar straining portion 1b with respect to the abutting portion 22 moves, so that the columnar straining portion 1b. However, it can be prevented from being tilted by the loading table 4. This point also greatly contributes to the improvement of the interference characteristic.

The present invention is not limited to the above-described and illustrated embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, the third strain gauges 13 to 16 on the beam 1c are
In the above-mentioned embodiment, an example is shown in which the shear strain is attached so that it can be detected. However, the bending strain may be attached to the upper surface and the lower surface of the beam so that the bending strain can be detected.

The first and second strain gauges 11 and 12 may be attached to only the upper portion of the columnar strain generating portion 1b, or both of the upper and lower portions, or the strain. The number of gauges can be appropriately increased or decreased.

The cross-sectional shape of the columnar strain generating portion 1b is not limited to the regular square columnar shape, and may be circular, polygonal, or hollow.

In addition, the cross-sectional area of the intermediate portion of the columnar strain generating portion 1b is increased, and the cross-sectional area between this intermediate portion and the external force introducing portion 1a and / or between this intermediate portion and the beam 1c is reduced to reduce this small disconnection. The part having the area may be used as the strain generating part. With such a configuration, it is possible to obtain a force detector which is strong against buckling.

Further, the scope of application of the present invention is not limited to the above-mentioned examples, but in the field of rehabilitation, for example, diagnosis of the degree of gait disorders, design and evaluation of assistive devices for persons with gait disorders, and degree of improvement before and after plastic surgery. It can also be applied to force plates used for judgment, etc.
Three-component force load (vertical load F) on the contact surface while the tire is running
Of course, the present invention can also be applied to a plate type tire running test machine, a tire characteristic testing machine, etc. used for measuring z, lateral load Fy, running direction front-back load Fx) and the like.

(e) Effects As described in detail above, according to the first invention, the external force introducing portion, the columnar strain generating portion, the beam and the pedestal portion are integrated,
Compact, lightweight, simple in structure and not particularly difficult to process, so it can be manufactured at low cost, and a multi-component force detector that can accurately detect each component force of the X-axis, Y-axis, Z-axis and the moment around the Z-axis. And according to the second invention,
Perhaps a force detection device that can significantly reduce the weight of the loading platform without deteriorating the interference characteristics, thereby significantly reducing the weight, increasing the natural frequency, and expanding the range of application by reducing the thickness. Can be provided.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing the structure of a main part of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is FIG. 1B- FIG. 4 is a perspective view showing a schematic configuration of the present invention, and FIG. 5 is a plan view for explaining the operation of the present invention. 1 ... Maybe force detector, 2 ... base, 3 ... intermediate plate, 4 ... loading platform, 5 ... connecting member, 6 ... clamping mechanism, 11-16 ... strain gauge, 19 ... flange Part, 22 ... Abutting part, 24 ... Diaphragm, 25 ... Mounting member, 26 ... Receiving member, 29-31 ... Cover member.

Claims (2)

[Claims] 1. A strain gauge is attached to a plurality of locations of a flexure element that elastically deforms when an external force is applied, and the strain gauges separate a plurality of electric signals corresponding to the external force applied from a plurality of directions. In the obtained force detector, an external force introducing portion having a large rigidity formed on one end side of the columnar strain generating body, a columnar strain generating section whose one end side is connected to the external force introducing section, and an axis of the columnar strain generating section. At least four beams extending in a direction orthogonal to each other and one end side of which is connected to the other end side of the columnar strain generating section, a pedestal portion having high rigidity connected to the other end of the beam, and the columnar strain generating section. A first strain gauge and a second strain gauge which are attached to the respective surfaces which are orthogonal to each other and which detect the component forces in the X-axis direction and the Y-axis direction, and which are attached to the respective beams. The component force in the Z-axis direction is detected. When a force is applied to the external force introducing portion from an arbitrary direction, the X-axis and the Y-axis are provided by the first, second and third strain gauges. , A force detector characterized in that the electric signals corresponding to the forces of the respective axial components of the Z axis are separately obtained. 2. An external force introducing portion having high rigidity is formed on one end side, and a columnar strain generating portion is connected to the external force introducing portion, and the other end side of the columnar strain generating portion is orthogonal to the axis of the columnar strain generating portion. At least four beams extending in the same direction are connected, and a rigid base is connected to the other ends of these beams, and A first strain gauge and a second strain gauge attached to each of the orthogonal planes for detecting the component forces in the X-axis direction and the Y-axis direction respectively, and a first strain gauge attached to the beam for detecting the component force in the Z-axis direction. A plurality of possibly force detectors having three strain gauges;
A base for fixing the pedestal portion of each of these multiple component force detectors, and a direction orthogonal to the axial direction of the columnar strain generating portion while making contact with each external force introducing portion of this multiple component force detector in a point contact state. A flat loading platform connected to the external force introducing section via a coupling member for transmitting a force acting on the load introducing section to the load introducing section and facing the base in parallel with each other, and at a predetermined interval with respect to the loading platform. A multi-component force detecting device, comprising: a flat intermediate plate that is arranged to face each other and connects each of the external force introducing portions of the multi-component force detector.