JPH046509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flexible grasping mechanism that can flexibly grasp and hold a workpiece.

There is a need in the industry for a gripping mechanism that satisfies the following conditions: adaptability to the shape of the workpiece, flexibility due to stress distribution during gripping, adaptability to any shape, gripping the workpiece with equal pressure, and easy control. A flexible grasping mechanism that can meet such demands is well known, for example, as disclosed in Japanese Patent Publication No. 13874/1983.

This mechanism is as shown in FIGS. 11 to 13, and a cord-like grasping body 21 is constructed from a multi-articulated body 22 formed by rotatably connecting a large number of links 23, 23 to each other. One end of the grasping body 21 is a supporting end,
It is held in a cantilevered manner with the other end as a free end, and an actuator for generating gripping torque is provided at each joint of the gripping body 21, and the torque generated by the actuator is applied along the axial length of the multi-jointed body 22. This basic structure is designed to decrease in a quadratic manner from the supporting end toward the free end.

In this way, the entire gripping body 21 can grip the workpiece with a uniform force, and the pulley and wire system can generate torque under predetermined conditions at each joint. Alternatively, the torque transmission wheel of the chain sprocket has a limit on the minimum winding radius depending on the size of the wire 26 or the chain, so even if you try to make it smaller, it cannot be made smaller than the limit. As the width dimension increased, it became difficult to make the entire hand compact.

Furthermore, since this gripping body 21 uses a torque transmission wheel such as a pulley or a chain sprocket, the torque transmission conditions for gripping and release are completely equal, and it is impossible to change the torque between the two movements. For example, there were problems in that even if you tried to grip the device slowly and surely and release it quickly, it was not easy to do so.

The present invention has been developed in response to the above-mentioned circumstances, and is designed to make the hand structure more compact, allow for a relaxed grasping operation, ensure reliable operation with an appropriate grasping force, and release the hand. The purpose of this is to enable the time to be quickly moved to the restoring position to reduce loss time.

Accordingly, the present invention provides a structure in which the above-mentioned grasping body is connected to each link as an element member forming a multi-joint body on the grasping side and the anti-grasping side across the pivot axis of each joint, and A grasping side pin and an outer circumferential side pin are respectively provided parallel to the support shaft, and one end of a grasping sheet made of a thin metal strip is fixed to the free end of the multi-segment body, and is connected to each pivot shaft. After successively passing through the space between the corresponding grasping side pin and reaching the supporting end side of the multi-section body, the other end is connected to an actuator such as a cylinder to form a grasping torque transmission member, and this grasping sheet A restoring sheet-like material having a structure similar to that of the multi-joint object is fixed at one end to the free end of the multi-joint body, and is sequentially passed through the space between each pivot shaft and the corresponding outer peripheral pin to form the multi-joint body. After reaching the supporting end side of the body, the other end is connected to a means for applying a constant tension such as a spring to form a restoring torque transmission member, and the grasping sheet-like object is brought into contact with the grasping side pin. The distance of each grasping side pin from the pivot shaft is set to a predetermined condition so that the grasping torque generated during the gripping process decreases in a quadratic manner from the supporting end toward the free end along the axial length of the multi-section body. It is possible to equalize the contact force when each grasping side pin dispersively contacts the circumferential surface of the workpiece, and also to equalize the contact force in the grasping direction. During the bending operation, the supporting end side, which is the hand, bends first, so that it conforms to the workpiece quickly and smoothly. By setting the relationship appropriately, it is possible for the free end side, which is the hand, to move away from the workpiece in advance during the restoring operation, and to perform the restoring action more quickly than when gripping the workpiece as a whole. Furthermore, since the torque actuator is structurally formed from a small-diameter pin and a thin sheet-like material, it can be made compact and narrower than a pulley or the like. The purpose of the period was achieved.

Each embodiment of the mechanism of the present invention will be described in detail below based on the accompanying drawings.

As shown in FIGS. 1 and 2, one example of the flexible grasping mechanism according to the present invention is a cord-like grasping mechanism formed from a multi-articulated body 2 formed by sequentially connecting a large number of links 3, 3 so as to be rotatable to each other. body 1, grasping side pins 4, 4, outer peripheral side pins 5, 5, grasping sheet-like material 6, restoring sheet-like material 7, actuator 8, and springs 9, 9.
and are provided as element members.

The link 3 in the grasping body 1 is long in the direction of the rotation axis, and has a diameter slightly larger than the diameter of the pivot shaft 12 in the direction perpendicular to this, except for the base side boss portion 13 that fits into the pivot shaft 12. It is formed into a thick plate body, and its distal end is connected to the base side boss portion 13 of the adjacent link 3 via the pivot shaft 12,
The base side boss portion 13 is connected to the tip end portions of adjacent links 3 via a pivot shaft 12.

Note that the link 3 serving as the supporting end, that is, the first
The link 3 at the left end in FIGS. 2 and 2 has a boss portion 13 rotatably attached to the holding member 10 via a pivot shaft 12.

Therefore, the links 3, 3, except for the free end (the rightmost link 3 in FIG. 1), are pivoted on the grasping side and the anti-grasping side across the pivot shaft 12 of each joint. Gripping side pins 4, 4 and outer peripheral side pins 5, 5 are fixed to the tip of each link 3, 3, respectively, at an appropriate interval from the shaft 12 and in parallel with each other. 5 is fixed to the link 3 in such a manner that it is perpendicular to the link 3, for example.

The pair of grasp side pins 4 and outer peripheral side pins 5 are made of thin round bars, and are fixed to a support bar attached to the tip of the link 3 in a T-shape, or made of thin flat round bars. As shown in the figure, it is provided on both sides of the pivot shaft 12 by means such as fixing a square ring to the tip of the link 3 at its center line.

Next, the grasping sheet-like material 6 and the restoring sheet-like material 7 are made of thin metal strips, etc., as described above, and are made of a series of material such as metal ribbons, which are used to measure approximately 1/4 of the total length from both ends.
is fixed to the tip of the link 3 at the most distal or free end of the multi-segmented body 2 with screws, and the parts near both ends are attached to the restoring sheet-like materials 7, 7, and the parts near the center are grasped and attached to the sheet-like material 6. , 6.

The grasping sheet-like material 6 is sequentially passed through the space between each pivot shaft 12 and the corresponding grasping-side pins 4, 4 to reach the support end side of the multi-section body 2, and then the other end is It is connected to the active end of an actuator, such as a pneumatic cylinder, attached to the holding member 10, so that the grasping sheet 6 can be pulled towards the holding member 10 and relaxed on the contrary.

In addition to the linear motion mechanism, a rotation mechanism such as a winding motor may be used as the actuator.

On the other hand, the restoration sheet-like material 7 has each pivot shaft 12
and the corresponding outer peripheral side pins 5, 5 to reach the support end side of the multi-section body 2, and then the other end is connected to the spring 9 attached to the holding member 10.
The restoring sheet material 7 is always kept under constant tension by being connected to a means for applying a constant tension, such as the following.

Note that the tension applying means in this case is not limited to a coil spring, but may also be any other means such as a pneumatic cylinder or a torque motor.

In this way, by arranging both the sheet-like objects 6 and 7 in relation to the multi-articulated body 2, the grasping sheet-like object 6 is brought into contact with the respective grasping-side pins 4 and 4, and the actuator 8 is formed into a grasping torque transmission member that transmits the torque of 8 to each link, and on the other hand, the restoring sheet material 7 applies the tension of the spring 9 to each link 3, 5 while in contact with the respective outer peripheral side pins 5, 5. 3
The restoring torque transmission member is formed to transmit the restoring torque to the restoring torque.

The outline of the structure of the flexible grasping mechanism is as explained above, and when the actuator 8 is operated in the rod retracting direction, the grasping sheet-like material 6 is pulled toward the holding member 10, and the multi-articulated body is 2 and 2 are bent inward in the direction of the center line and gripped so as to wrap around the workpiece W as shown in the third figure, and when the actuator 8 is operated in the direction of extruding the rod, the restoring sheet-like material 7 is held. By being pulled toward the member 10 side, the multi-segment bodies 2, 2 become the fourth
As shown in the figure, they are in a restored state in which they are each curled outward.

Here, the mechanical principle for gripping the workpiece W by the gripping body 1 with equal pressure from the surroundings is as described in detail in Japanese Patent Publication No. 13874/1983, and gripping the workpiece W with equal pressure. It has been found that the gripping torque applied to the members of each link 3, 3 that come into contact with the workpiece W, that is, the gripping side pins 4, 4, should be reduced quadratically along the axial length of the gripping body 1. It's on.

Therefore, it is only necessary to specify the structure so as to satisfy the above-mentioned torque setting conditions. Therefore, the present invention aims at adjusting the grasping torque generated when the grasping sheet-like object 6 is brought into contact with the grasping side pins 4, 4, respectively. In order to decrease quadratically from the support end to the free end along the axial length of the multi-section body 2, the circumference of the grasping side pins 4, 4 is increased from the center of the pivot shaft 12 in each link 3, 3. The structure is such that the distance Rpi (see Figure 2) to the closest point on the surface gradually decreases from the supporting end to the free end.

The specific conditions for gradual reduction in this case are as follows.

That is, the pivot shaft 12 in each link 3, 3
The distance from the center to the closest point on the peripheral surface of the outer peripheral pins 5, 5 is Rpo, and the base side boss portion 13 of each link 3, 3 under the state shown in FIG.
When Rjo is the diameter from the shaft hole center to the circumferential surface in the direction of outer pin 5, Rpi−Rpo or Rpi
The value of -Rjo is made to decrease in a quadratic manner from the supporting end toward the free end.

Note that the values of Rpo and Rjo are set to be equal for each link 3, 3.

By doing this, it is possible to equalize the torque of the grasping side pins 4, 4 when grasping the workpiece W.

However, the above example further includes the grasping sheet-like object 6
The bending torque generated when the links 3, 3 are brought into contact with the circumferential surface of the proximal boss portion 13 of each link 3, 3 decreases in a quadratic manner from the supporting end toward the free end along the axial length of the multi-jointed body 2. Therefore, under the condition shown in the first figure in which the multi-segmented body 2 is extended linearly, the circumferential surface in the direction of the grasping side pin 4 from the center of the shaft hole in the boss portion 13 of each link 3, 3. The structure is such that the diameter Rji gradually decreases from the supporting end toward the free end.

An example of a specific condition for gradual reduction in this case is that the value of Rji-Rpo or Rji-Rjo decreases in a quadratic manner from the supporting end toward the free end. It is.

With such conditions, when the grasping operation is performed from the restored state shown in Fig. 4, the support end on the hand side can be brought into contact with the workpiece W first, and the grasping operation can be carried out smoothly and quickly. It will be done.

Next, to explain the grasping operation by the above-mentioned grasping mechanism, when the actuator 8 is actuated and tension is applied to the grasping sheet-like object 6, each link 3, 3 is moved by a spring 9.
The restoring sheet material 7 overcomes the tension exerted by the restoring sheet material 7 and bends in the direction of enveloping the workpiece W, that is, inwardly, from the state shown in FIG. 4 to the state shown in FIG. 3.

As is clear from FIG. 3, when the workpiece W is grasped, the grasping sheet-like object 6 is attached to the grasping side pins 4,
4, while the restoring sheet material 7 is tensioned along the diameter of the base side boss portion 13 of each link 3, 3.
It is in a tense state along the peripheral surface corresponding to Rjo.

At this time, the links 3 and the gripping sheet-like object 6 are in a state where the sheet-like object 6 is fixed to the link 3 as shown in FIG. 7, since each link 3, 3 is restrained by the workpiece W. They can be considered to be equivalent, and therefore, torque (M=T·Rpi, where T is tension) acts on each connection point where each pivot shaft 12 exists.

Here, the torque due to the grasping sheet-like material 6 is
Rpi decreases in a quadratic manner from the support end side to the free end side, and the torque due to the restoring sheet material 7 is constant at each connection point, so the link 3 acts on the workpiece W. The distributed force becomes uniform, and it becomes possible to grasp the workpiece W flexibly.

Next, when releasing the grasping, the actuator 8 is operated in the opposite direction to reduce the tension of the grasping sheet-like object 6, and the tension of the restoring sheet-like object 7 by the spring 9 overcomes the link 3, 3. is separated from the workpiece W and bent toward the outer circumference.

At this time, since the torque around the connection point caused by the grasping sheet 6 becomes smaller as it goes toward the tip as described above, the release starts from the tip and gradually moves toward the support end. .

Then, when the workpiece W is bent toward the gripping side, the final posture shown in FIG. It begins to bend and gradually moves toward the free end.

By the way, the distance Rpi of the grasp side pin 4 with respect to the pivot shaft 12 and that of the outer peripheral side pin 5 (Rpo) can be set to arbitrary values at the time of design, so the release side can be operated quickly to reduce loss time. Weigh the
On the other hand, it is also possible to operate the grasping side lightly and slowly.

In the example shown in the first figure, the grasping body 1 is formed from a pair of multi-jointed bodies 2, but a mechanism for grasping with only one multi-jointed body 2 may be used.

Next, FIG. 5 and FIG. 6 show another embodiment of the present invention, in which the grip side pins 4, 4 are locked to one end of the leaf spring 14 via a U-shaped member 15. , the other end of the leaf spring 14 is fixed to each link 3, and the conditions for the distance Rpi of the grasp side pin 4 are the same as in the example shown in FIG.

Since the leaf spring 14 of this multi-joint body 2 has elasticity, it can elastically support the workpiece under gripping conditions, and in addition to making the distributed force more uniform, it is expected to improve flexibility due to the cushion function. .

FIG. 8 shows another embodiment of the present invention, in which two grip side pins 4 are used for each pivot shaft 12,
The grasping side pins 4, 4 are characterized in that they are provided close enough to each other to allow the grasping sheet-like object 6 to be inserted therethrough, and in parallel to each other.

The grasping mechanism having such a structure is capable of always maintaining the distance between the pivot shaft 12 of each node and the sheet-like object 6, which changes quadratically, at a set value. , it is possible to reliably grasp workpieces of arbitrary shapes.

Next, what is shown in FIGS. 9 and 10 relates to an embodiment of the present invention, and whereas what has been described so far has a structure in which the grasping side pin 4 is fixed to the corresponding link 3. In this example, a grasp side pin 4, an outer peripheral side pin 5, and a support bar that supports both pins 4, 5 are rotatably provided around a pivot shaft 12.

With such a structure, it is possible to position the grasping side pin 4 in the direction of the equidistant line of the angle formed by the adjacent links 3, 3 when the workpiece is grasped, and thus the grasping side pin 4 The gripping force of the gripping sheet-like object 6 acting through the gripping sheet material 6 is more likely to match the normal direction to the workpiece surface, and the gripping side pin 4
can be secured in a predetermined position so as not to move, and
This enables reliable understanding.

Although not shown, the other ends of a pair of springs each have one end fixed to adjacent links 3, 3 connected via a pivot shaft 12 to a support bar that supports the grip side pin 4. If the support bar is pulled and balanced by the same spring force from both links 3, 3, the grasping side pin 4 can be positioned reliably, which is a preferable embodiment.

Next, the effects of the present invention are as follows.

(b) The structure is such that the thin plate-like links 3, pins 4, 5, and sheet-like objects 6, 7 are arranged so that the thickness direction and radial direction are perpendicular to the movement axis for gripping and releasing, making it compact. It is possible to construct a hand with a thinner and simpler structure than the conventional mechanism using pulleys, and since the torque is transmitted by the sheet-like material 6, the wire It can generate a strong grasping force compared to the conventional one.

(b) Since the distances between the grasping side pin 4 and the outer peripheral side pin 5 from the pivot shaft 12 are not the same and can be changed arbitrarily at the time of design, it is possible to set the grasping torque and the release torque to different values, You can set the appropriate torque for each.

That is, at the time of grasping, the grasping sheet-like material 6 is in contact with the grasping-side pin 4, and the restoring sheet-like material 7 is in contact with the base-side boss portion 13 of the link 3, so that Rpi>Rjf and Rpo>Rjo. From this relationship, the difference between the gripping torque around the connection point and the torque for release becomes large, and the effect of gripping can be doubled. On the other hand, when releasing, this relationship is reversed, and the grasping sheet-like object 6 is moved to the base side boss portion 13.
In addition, since the restoring sheet-like material 7 can be brought into contact with the outer peripheral pin 5, it is possible to reduce the difference between both torques and quickly release the product, thereby shortening the time required for release.

(c) Base side boss portion 1 with which the grasping sheet-like object 6 contacts
If the radius Rji of No. 3 is made to decrease in a quadratic manner toward the free end, it will be grasped first from the support end side, which is the hand side, and released first from the free end side, which is the hand side. Therefore, the grip release operation is performed smoothly.

[Brief explanation of drawings]

FIG. 1 is a front view of one embodiment of the present invention, and FIG.
The figure is also a plan view, and Figures 3 and 4 are the 1st
5 is a plan view showing the main parts of another embodiment of the present invention; FIG. 6 is a needle of the grasping side pin portion in FIG. 5. 7 is a sectional view of a link portion for explaining the grasping torque according to the present invention, FIG. 8 is a perspective view of the vicinity of the grasping side pin of the embodiment according to the present invention, and FIGS. 9 and 10 are A plan view showing a grasping state and a plan view showing a releasing and restoring state according to an embodiment of the present invention, 11th
Figures 13 to 13 show aspects of the conventional gripping mechanism, with Figure 11 being a plan view showing the gripping state, Figure 12 being an enlarged side view of a part of the multi-segmented body, and Figure 13 being B of Figure 12. -B diagram. 1...Grasp body, 2...Multi-segment body, 3...Link,
4... Grasping side pin, 5... Outer circumferential side pin, 6... Sheet-like material for grasping, 7... Sheet-like material for restoring, 8...
... Actuator, 12 ... Pivot shaft, 13 ... Base side boss section.

Claims (1)

[Scope of Claims] 1. A cord-shaped grasping body 1 formed from a multi-segmented body 2 formed by rotatably connecting a large number of links 3, 3 to each other. Attached to each link 3, 3 on the grasping side, and
Grasping side pins 4, 4 and outer circumferential side pins 5, 5 are provided parallel to the pivot shaft 12, while a grasping sheet-like material 6, one end of which is fixed to the free end of the multi-articulated body 2, is attached to each pivot. After sequentially passing through the space between the support shaft 12 and the corresponding grasping side pins 4, 4 and reaching the supporting end side of the multi-section body 2, the other end is connected to an actuator 8 such as a cylinder, In addition to being formed into a grasping torque transmitting member, a restoring sheet-like material 7 is fixed at one end to the free end of the multi-articulated body 2, and between each pivot shaft 12 and the corresponding outer peripheral side pin 5, 5. After successively passing through the spaces in the space to reach the support end side of the multi-section body 2, the other end is connected to a means for applying a constant tension such as a spring,
The restoring torque transmission member transmits the gripping torque generated when the gripping sheet-like object 6 is brought into contact with the gripping side pins 4, 4 from the support end along the axial length of the multi-section body 2. The distance Rpi from the center of the pivot shaft 12 in each link 3, 3 to the closest point on the circumferential surface of the grip side pin 4 gradually decreases from the support end toward the free end so that it decreases quadratically toward the free end. A flexible grasping mechanism characterized by: 2 The distance from the center of the pivot shaft 12 in each link 3, 3 to the closest point on the circumference of the outer pin 15 is Rpo,
When the diameter from the center of the shaft hole in the base side boss portion 13 of each link 3, 3 to the circumferential surface in the direction of the outer circumferential pin is Rjo with the multi-segment body 2 extended in a straight line, Rpi−Rpo The flexible grasping mechanism according to claim 1, wherein the value of Rpi-Rjo is set to decrease quadratically from the supporting end toward the free end.