JP2021115679A - Gripping force adjusting device - Google Patents

Abstract

To provide an adjusting device that enables gripping force of a pair of claw parts to be adjusted with good accuracy, even if the claw parts get warped.SOLUTION: A gripping force adjustment device 10, which adjusts gripping force of a pair of claw parts 16, for a servo hand 12 which comprises the pair of claw parts 16 opposed to each other in a separation direction D16, where an interval in the separation direction D16 of the pair of claw parts 16 is varied by driving of a servo motor 18, comprises: a first connection part 24 that is connected to either of the pair of claw parts 16; a second connection part 26 that is connected to the other; an energizing mechanism 28, provided between the first connection part 24 and the second connection part 26, and generating energization force corresponding to the interval; and a turning mechanism 32, provided between the first connection part 24 and the energizing mechanism 28, and making the first connection part 24 and the second connection part 26 turn relatively to each other in response to warpage of the pair of claw parts 16, so as to vary a direction D40 of the energization force in accordance with the warpage.SELECTED DRAWING: Figure 4

Description

The present invention relates to a gripping force adjusting device. In particular, the present invention relates to a gripping force adjusting device used for adjusting the gripping force of a pair of claws included in a servo hand.

As disclosed in Patent Document 1, an industrial robot hand (servo hand) is well known. Further, Patent Document 1 discloses that the gripping force of the servo hand can be detected by the load cell.

Japanese Unexamined Patent Publication No. 2012-218084

When the servo hand has a pair of claws and the pair of claws grips the object to be gripped, the warp of the pair of claws may become a problem when trying to adjust the gripping force. ..

For example, the load cell described above detects the magnitude of the load (grip force) applied to itself, but the load is not correctly applied to the load cell when the claw portion is warped. In this case, it is difficult for the load cell to accurately detect the gripping force of the pair of claws. Further, in this case, since it is difficult to detect the gripping force with high accuracy, it is naturally difficult to adjust the gripping force with high accuracy.

Therefore, an object of the present invention is to provide a gripping force adjusting device capable of accurately adjusting the gripping force of a pair of claws even if the claws are warped.

One aspect of the present invention is to provide a pair of claws facing each other in the separation direction, and for a servo hand in which the distance between the pair of claws in the separation direction is changed by driving a servomotor, the pair of claws of the pair of claws. A gripping force adjusting device for adjusting the gripping force, the first connecting portion connected to the claw portion side of one of the pair of the claw portions, and the other of the pair of the claw portions. An urging mechanism provided between a second connecting portion connected to the claw portion side, the first connecting portion, and the second connecting portion to generate an urging force according to the interval, and the above. By being provided between the first connecting portion and the urging mechanism, the first connecting portion and the second connecting portion are rotated relative to each other according to the warp of the pair of the claw portions. A rotation mechanism that changes the direction of the urging force according to the warp is provided.

According to the aspect of the present invention, there is provided a gripping force adjusting device capable of accurately adjusting the gripping force of a pair of claws even if the claws are warped.

It is the whole block diagram of the servo hand of embodiment. It is a figure for demonstrating the configuration example of the conventional means for adjusting the gripping force of a pair of claws. It is a figure for demonstrating the case where the claw portion is warped during the adjustment by the means of FIG. It is an overall block diagram of the gripping force adjusting device of embodiment. It is a block diagram which shows the state which the gripping force adjusting device of embodiment is attached to the servo hand. It is a figure for demonstrating the case where the claw part is warped during the adjustment by the gripping force adjusting apparatus of embodiment.

The gripping force adjusting device of the present invention will be described in detail below with reference to the accompanying drawings, with reference to preferred embodiments.

[Embodiment]
Before explaining the gripping force adjusting device (hereinafter, simply "adjusting device") 10 of the present embodiment, the servo hand 12 which is the adjustment target of the adjusting device 10 will be described first.

FIG. 1 is an overall configuration diagram of the servo hand 12 of the embodiment.

As shown in FIG. 1, the servo hand 12 illustrated in the present embodiment includes a base portion 14, a pair of claw portions 16 provided on the base portion 14, and a servomotor 18. Of these, the servomotor 18 is driven by a drive current supplied from a drive device (servo amplifier) (not shown).

The pair of claw portions 16 are provided for gripping the gripping object W, and are provided on the base portion 14 so as to be _{separated from each other in a predetermined separation direction D 16.} In the present embodiment, it is assumed that the pair of claw portions 16 contains metal in the material. Although FIG. 1 shows an object (block member) having a rectangular cross section as an example of the gripping object W, the gripping object W is not limited to this as a matter of course.

One of the pair of claw portions 16 is connected to the rotation shaft of the servomotor 18 via a conversion mechanism (not shown) provided in the base portion 14. The conversion mechanism (not shown) provided in the base portion 14 converts the rotational motion of the rotating shaft into a linear motion and transmits it to the claw portion 16 connected to itself.

The servo hand 12 having the above configuration changes the distance (separation interval) between the _{pair of claws 16 in the separation direction D 16} by driving the servomotor 18, and the pair of claws 16 holds the gripping object W. Can be grasped.

At this time, the pair of claws 16 when gripping the gripping object W grips the gripping object W with a gripping force in a direction parallel to the _{separation direction D 16.} In order to preferably maintain the state in which the gripping object W is gripped by the servo hand 12, it is desirable to adjust the gripping force of the pair of claws 16 so that the gripped object W does not fall.

FIG. 2 is a diagram for explaining a configuration example of a conventional means for adjusting the gripping force of a pair of claw portions 16.

As a means for adjusting the gripping force of the pair of claws 16, a load cell 20 is considered as shown in FIG. In the configuration of FIG. 2, the load cell 20 and the rigid columnar holding member 22 are _{gripped by a pair of claws 16} in a state of being lined up in the separation direction D 16. The holding member 22 is gripped in a state in which _{its axial direction D 22 is parallel to the separation direction D 16} which is the direction of the gripping force.

_{According to the configuration of FIG. 2, the load in the separation direction D 16} that correlates with the gripping force of the servo hand 12 is efficiently applied from the holding member 22 to the load cell 20. At this time, if the correlation between the load detected by the load cell 20 and the gripping force is investigated in advance by an experiment, the load cell 20 detects the load applied to itself and adjusts the gripping force based on the load. You should be able to.

FIG. 3 is a diagram for explaining a case where the claw portion 16 is warped during the adjustment by the means of FIG.

However, the claw portion 16 of the servo hand 12 may warp due to the repulsive force received from the holding member 22 and the load cell 20. As an example, FIG. 3 illustrates a case where the claw portion 16 is warped by an angle θ.

In this case, the direction of the load is tilted by an angle θ with respect to the load cell 20. Therefore, the load is not correctly applied to the load cell 20, and it becomes difficult to accurately obtain the gripping force by the means shown in FIG. As a result, it becomes difficult for the operator to accurately adjust the gripping force.

Therefore, in the present embodiment, the adjusting device 10 described below makes it possible to accurately adjust the gripping force of the pair of claws 16 even if the claws 16 of the servo hand 12 are warped. .. Hereinafter, the configuration of the adjusting device 10 of the present embodiment will be described.

FIG. 4 is an overall configuration diagram of the adjusting device 10 of the embodiment.

The adjusting device 10 includes, for example, a metal as a material, and an urging mechanism provided between the first connecting portion 24, the second connecting portion 26, and the first connecting portion 24 and the second connecting portion 26. 28, a ball screw mechanism 30, and a rotation mechanism 32 are provided.

Hereinafter, each element constituting the adjusting device 10 will be described step by step. The first connecting portion 24 is connected to one of the claw portions 16 side of the pair of claw portions 16 included in the servo hand 12. A magnet 34 is provided in the first connecting portion 24. When the first connecting portion 24 and the claw portion 16 come into contact with each other, the magnet 34 magnetically pulls the claw portion 16 toward the first connecting portion 24, thereby causing the first connecting portion 24 and the claw portion 16 to come into contact with each other. Easy to connect with.

The second connecting portion 26 is connected to the other claw portion 16 side of the pair of claw portions 16. The magnet 34 is also provided in the second connecting portion 26. The magnet 34 provided in the second connecting portion 26 easily realizes these connections by magnetism when the second connecting portion 26 and the claw portion 16 come into contact with each other.

The urging mechanism 28 includes a housing 36, a pressing member 38, and an elastic member 40. Of these, the housing 36 is a box-shaped member having a first surface 36a provided with an opening 42 and a second surface 36b facing the first surface 36a. In the first surface 36a and the second surface 36b, the first surface 36a is on the first connecting portion 24 side, and the second surface 36b is on the second connecting portion 26 side. Further, the second surface 36b of the housing 36 is in contact with and fixed to the second connecting portion 26. The means for fixing is not particularly limited, but it is preferable that the housing 36 is removable from the second connecting portion 26, for example, by screwing. It is not essential to make it removable, and the housing 36 and the second connecting portion 26 may be connected (fixed) by welding, for example.

The pressing member 38 prevents the columnar pressing portion 44 partially housed in the housing 36 and a part of the pressing portion 44 housed in the housing 36 from coming out of the housing 36 through the opening 42. It has a flange portion 46 and a flange portion 46. Of these, the pressing portion 44 is connected to the ball screw mechanism 30 on the first connecting portion 24 side. The means for connecting the first connecting portion 24 side and the pressing member 38 is not particularly limited, but it is preferable that the means is removable like the means for connecting the housing 36 and the second connecting portion 26.

The elastic member 40 is, for example, a compression coil spring, which has elasticity and generates an urging force having a magnitude correlated with its own expansion / contraction (compression) amount. One end of the elastic member 40 is connected to the second surface 36b side of the housing 36, and the other end is connected to the pressing portion 44 in the housing 36.

The ball screw mechanism 30 has a screw shaft 48 connected to the pressing member 38 side and a nut portion 50 having a nut connected to the rotating mechanism 32 side and screwed to the screw shaft 48. However, the nut portion 50 may be connected to the pressing member 38 side, and the screw shaft 48 may be connected to the rotating mechanism 32 side. The ball screw mechanism 30 makes it possible to easily adjust the distance between the pressing member 38 and the rotating mechanism 32. The circulation type of the ball screw mechanism 30 is not particularly limited, but is, for example, a top type.

By the distance between the pressing member 38 and the rotating mechanism 32 is adjusted, the result, the total length L ₁₀ of the adjusting device 10 from the first connecting portion 24 toward the second coupling portion 26 is adjusted NS. That is, in the present embodiment, the operator can easily change _{the total length L 10} of the adjusting device 10 according to the separation interval of the pair of claw portions 16 by operating the ball screw mechanism 30.

The rotating mechanism 32 includes a first link member 52 connected to the first connecting portion 24 side, a second link member 54 connected to the urging mechanism 28 side, a first link member 52, and a first link member 52. It is a link mechanism having a shaft member 56 that rotatably inserts the link members 54 of 2 into each other. In the present embodiment, the first link member 52 is fixed to the first connecting portion 24, and the second link member 54 is fixed to the nut portion 50 of the ball screw mechanism 30.

The rotating mechanism 32 causes the first connecting portion 24 and the second connecting portion 26 to rotate relative to each other according to the warp of the pair of claw portions 16, and as a result, urge the first connecting portion 26 and the second connecting portion 26 according to the warp. The direction of the urging force generated by the mechanism 28 changes.

FIG. 5 is a configuration diagram showing a state in which the adjusting device 10 of the embodiment is attached to the servo hand 12.

When adjusting the gripping force of the pair of claws 16 when gripping the gripping object W, first, as shown in FIG. 5, a pair of servo hands 12 are provided prior to gripping the gripping object W. The adjusting device 10 is attached to the claw portion 16. For attachment, one of the pair of claws 16 included in the servo hand 12 is connected to the first connecting portion 24, and the other claw portion 16 is connected to the second connecting portion 26. To be done by.

At this time, the direction of the urging force of the elastic member 40, i.e. the expansion and contraction direction D ₄₀ of the elastic member 40, and a contact surface 16a of each of the pair of claw portions 16 with respect to the first connecting portion 24 and second connecting portion 26 Make it orthogonal. As a premise, at the stage of attaching the adjusting device 10 to the pair of claw portions 16, the pair of claw portions 16 are not warped, and the contact surface 16a of one claw portion 16 and the contact surface 16a of the other claw portion 16 are parallel to each other. It is assumed that you are doing.

Next, by driving the servomotor 18 of the servo hand 12 based on a predetermined torque command or speed command (rotational speed command), while applying a gripping force to the adjusting device 10, the pair of claws 16 The separation interval is brought close to the length of the gripping object W in the separation direction D _16. To drive the servomotor 18 based on a predetermined torque command or speed command, detectors such as a current sensor and an encoder are provided in the servomotor 18, and the drive device provides feedback control based on the information obtained from the detectors. It may be realized by doing.

The elastic member 40 is pressed by the pressing member 38 according to the magnitude of the gripping force applied to the adjusting device 10, and is compressed in the _{expansion / contraction direction D 40.} Further, the elastic member 40 generates an urging force having a magnitude corresponding to the amount of compression thereof.

This urging force affects the drive current supplied to the servomotor 18 according to its magnitude. That is, the servomotor 18 that controls the pair of claw portions 16 that apply the gripping force to the adjusting device 10 is driven so as to narrow the separation interval of the pair of claw portions 16 based on the torque command or the speed command. Here, the urging force generated by the elastic member 40 is a force that repels the narrowing of the distance between the pair of claws 16, and is a load that tends to hinder the driving based on the torque command or the speed command for the servomotor 18. Is. Therefore, when the elastic member 40 generates an urging force, a larger driving current is supplied from the driving device to the servomotor 18 in order to realize the driving based on the torque command or the speed command against the urging force. At this time, the magnitude of the drive current supplied to the servomotor 18 increases as the urging force increases.

As described above, in the state where the adjusting device 10 of the present embodiment is attached to the pair of claws 16, the larger the urging force of the elastic member 40, the larger the driving current of the servomotor 18. That is, in this state, the drive current of the servomotor 18 and the urging force of the elastic member 40 correlate with each other.

Further, since the amount of expansion and contraction increases according to the gripping force applied from the pair of claws 16 to the elastic member 40, the gripping force and the urging force that correlates with the amount of expansion and contraction are correlated from a bird's-eye view. .. From this, it is possible to specify the urging force according to the gripping force based on the gripping force desired to be generated when gripping the gripping object W. Further, the amount of expansion and contraction of the elastic member 40 required to generate the gripping force can be specified based on the correlation between the urging force and the amount of expansion and contraction.

Then, as described above, in the present embodiment, the drive current of the servomotor 18 and the urging force are correlated. Therefore, in the present embodiment, when the distance between the pair of claws 16 becomes the distance when the gripping object W is gripped, the elastic member 40 is expanded and contracted according to the required gripping force. If selected, the value of the drive current corresponding to the gripping force can be obtained.

After that, when the operator grips the gripping object W with the pair of claws 16, the operator adjusts the drive current of the servomotor 18 so as to obtain the value obtained as described above. As a result, when the pair of claws 16 grip the object W to be gripped, the gripping force of the servo hand 12 is adjusted to a gripping force corresponding to the driving current. As described above, by using the adjusting device 10 of the present embodiment, the operator can accurately adjust the gripping force of the pair of claw portions 16. Here, if a plurality of elastic members 40 (biasing mechanism 28) having different characteristics are prepared and configured to be appropriately replaceable (removable) in the adjusting device 10, various cases can be dealt with.

Further, in the present embodiment, even if the pair of claw portions 16 are warped, the expansion / contraction direction D ₄₀ of the elastic member 40 changes according to the warp, so that the expansion / contraction direction D ₄₀ is the second connecting portion 26. A state perpendicular to the contact surface 16a of the claw portion 16 on the side is preferably maintained.

FIG. 6 is a diagram for explaining a case where the claw portion 16 is warped during the adjustment by the adjusting device 10 of the embodiment.

For example, when the claw portion 16 (contact surface 16a) on the second connecting portion 26 side warps by an angle θ as shown in FIG. 6, the expansion / contraction direction D ₄₀ also tilts by an angle θ accordingly. In FIG. 6, the expansion / contraction direction of the elastic member 40 before the warp of the angle θ occurs in the claw portion 16 is _{indicated by D 40} , and the expansion / contraction direction of the elastic member 40 after the warp occurs is conveniently D'. It is shown by _40.

In this way, the rotating mechanism 32 included in the adjusting device 10 reduces the influence of the warp of the claw portion 16 on the amount of expansion and contraction of the elastic member 40, that is, the influence of the warp on the urging force generated by the urging mechanism 28. NS. As a result, the possibility that the warp affects the drive current is reduced. Therefore, in the present embodiment, even if the claw portion 16 is warped, the gripping force can be adjusted accurately based on the driving current.

In FIG. 6, the case where the second connecting portion 26 side of the pair of claw portions 16 is warped is illustrated, but the case where the claw portion 16 (contact surface 16a) on the first connecting portion 24 side is warped. However, in the present embodiment, the gripping force can be adjusted with high accuracy. That is, when the claw portion 16 on the side of the first connecting portion 24 is warped, the first connecting portion 24 rotates with respect to the urging mechanism 28 in accordance with the warp. Therefore, the influence of the warp on the amount of expansion and contraction of the elastic member 40, that is, the influence of the warp on the urging force generated by the urging mechanism 28 is reduced.

As described above, according to the present embodiment, there is provided an adjusting device 10 capable of accurately adjusting the gripping force of the pair of claw portions 16 even if the claw portions 16 are warped.

[Modification example]
Embodiments have been described above as an example of the present invention. Various changes or improvements can be made to the embodiments. Moreover, it is clear from the description of the scope of claims that such a modified or improved form may be included in the technical scope of the present invention.

(Modification example 1)
If it is not particularly necessary to adjust the total length L ₁₀ of the adjusting device 10, the ball screw mechanism 30 may be omitted from the configuration of the adjusting device 10. In that case, the second link member 54 may be fixed to the pressing member 38 instead of the ball screw mechanism 30.

Thereby, the configuration of the adjusting device 10 can be made simpler. Taking one example of need to adjust the overall length L ₁₀ of the adjusting device 10 is not especially, if it is, for example, spaced distance between the pair of claw portions 16 at the time of adjusting the gripping force is always regular intervals Can be considered.

(Modification 2)
The adjusting device 10 may further include a scale with a scale indicating the amount of expansion and contraction of the elastic member 40. The scale is provided, for example, in the housing 36.

As a result, the operator can visually recognize the amount of expansion and contraction of the elastic member 40, which is convenient for the operator.

(Modification example 3)
The above-described embodiment and each modification may be arbitrarily combined as long as there is no contradiction.

[Invention obtained from the embodiment]
The inventions that can be grasped from the above-described embodiments and modifications are described below.

A pair of claw facing in the direction of separation _{(D 16)} to (16), servo pair of the claw portion by the driving of the servo motor (18) is the distance in the spacing direction _{(D 16)} of (16) is changed Regarding the hand (12), it is a gripping force adjusting device (10) for adjusting the gripping force of the pair of the claw portions (16), and the claw portion (10) of one of the pair of the claw portions (16). A first connecting portion (24) connected to the 16) side and a second connecting portion (26) connected to the other claw portion (16) side of the pair of the claw portions (16). An urging mechanism (28) provided between the first connecting portion (24) and the second connecting portion (26) to generate an urging force according to the interval, and the first connecting portion ( It is provided between the urging mechanism (24) and the urging mechanism (28), and the first connecting portion (24) and the second connecting portion (26) are relative to each other according to the warp of the pair of the claw portions (16). A rotation mechanism (32) that changes the direction of the urging force (D _{40) in response to the warp is provided.}

This provides a gripping force adjusting device (10) capable of accurately adjusting the gripping force of the pair of claw portions (16) even if the claw portions (16) are warped.

The rotating mechanism (32) has a first link member (52) connected to the first connecting portion (24) side and a second link member connected to the urging mechanism (28) side. (54) and a shaft member (56) for rotatably inserting the first link member (52) and the second link member (54) into each other may be provided. As a result, the rotation mechanism (32) constitutes a link mechanism that rotates the first link member (52) and the second link member (54) relative to each other.

The gripping force adjusting device (10) has a screw shaft (48) connected to one of the urging mechanism (28) and the rotating mechanism (32), and a nut portion (50) connected to the other. ), And a ball screw mechanism (30) having the above. This makes it possible to easily change _{the total length (L 10} ) of the adjusting device (10).

10 ... Gripping force adjusting device 12 ... Servo hand 16 ... Claw part 18 ... Servo motor 24 ... First connecting part 26 ... Second connecting part 28 ... Biasing mechanism 30 ... Ball screw mechanism 32 ... Rotating mechanism 48 ... Screw Shaft 50 ... Nut portion 52 ... First link member 54 ... Second link member 56 ... Shaft member D ₁₆ ... Separation direction D ₄₀ ... Elastic member expansion / contraction direction (direction of urging force)
L ₁₀ : Overall length of gripping force adjusting device W: Object to be gripped

Claims (3)

Gripping for adjusting the gripping force of the pair of claws for a servo hand that has a pair of claws facing each other in the separation direction and whose spacing of the pair of claws changes in the separation direction by driving a servomotor. It ’s a force regulator,
A first connecting portion connected to the claw portion side of one of the pair of claw portions,
A second connecting portion connected to the other claw portion side of the pair of the claw portions,
An urging mechanism provided between the first connecting portion and the second connecting portion to generate an urging force according to the interval, and an urging mechanism.
By being provided between the first connecting portion and the urging mechanism, the first connecting portion and the second connecting portion are rotated relative to each other according to the warp of the pair of the claw portions. , A rotating mechanism that changes the direction of the urging force according to the warp,
A gripping force adjusting device. The gripping force adjusting device according to claim 1.
The rotating mechanism includes a first link member connected to the first connecting portion side, a second link member connected to the urging mechanism side, the first link member, and the second link member. A gripping force adjusting device having a shaft member that rotatably inserts the link members of the above. The gripping force adjusting device according to claim 1 or 2.
A gripping force adjusting device further comprising a ball screw mechanism having a screw shaft connected to one of the urging mechanism and the rotating mechanism, and a nut portion connected to the other.

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