JPH0242636B2 - - 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.

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

This mechanism is as shown in FIGS. 6 to 8, and consists of a multi-segment body 22 formed by rotatably connecting a large number of links 23, 23 to a cord-shaped grasping body 2.
1, the grasping body 21 is held in a cantilever manner with one end as a support end and the other end as a free end, and an actuator for generating a grasping torque is disposed at each joint of the grasping body 22, The basic structure is such that the torque generated by the actuator is quadratically reduced along the axial length of the multi-jointed body 22 from the support 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, and therefore the direction of movement for grasping cannot be made smaller. The parallel width dimension became large, making it difficult to store the entire hand compactly.

Furthermore, since this gripping body 21 uses a torque transmission vehicle 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 both movements. For example, there was a problem in that even if one tried to grasp 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 these circumstances, and aims to make the structure of the hand portion more compact, and to achieve reliable operation by ensuring appropriate speed and movement during grasping and release. The purpose is to do what is possible.

To this end, the present invention provides a grasping bar that is supported on each node of the multi-section body and held parallel to each node at the grasping side position, and a grasping bar made of a thin metal strip or the like. sheet-like material for
One end is fixed to the free end of the multi-joint body, and the other end is attached to a cylinder, etc. The grasping torque transmitting member is connected to the actuator, and each joint is provided with a release torque generating spring having elasticity in the direction of resisting the acting force of the actuator. Grasp from the center of the pivot axis of each joint so that the gripping torque generated when an object comes into contact with the gripping bar decreases from the supporting end to the free end along the axial length of the multi-joint body. The distance to the contact surface of the workpiece sheet is gradually decreased from the support end to the free end, and the contact force when each gripping bar comes into contact with the circumferential surface of the workpiece in a distributed manner. In addition, when bending in the grasping direction, the support end side that is the hand is bent first, making it possible to quickly and smoothly adapt to the workpiece. and, on the other hand,
By appropriately setting the elastic force of the spring for generating release torque at each joint, the free end side, which is the hand, will be released from the workpiece in advance during the restoring operation from grasping the workpiece, and the entire It is also possible to operate the actuator more quickly than when gripping, and since the torque actuator is formed from a small-diameter gripping bar and a thin sheet-like material, it is easy to use on pulleys, etc. In comparison, it can be made into a narrow and compact structure, and the intended purpose has been achieved here.

Embodiments of the mechanism of the present invention will be described in detail below with reference to 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. It includes a body 1, gripping bars 4, 4, a gripping sheet 5, an actuator 6, and a spring 7 as element members.

The links 3 in the grasping body 1 are long in the rotational axis direction and formed into thin plates in the direction perpendicular to this, and the tip bearing portion 3B is connected to the base side bearing portion 3A of the adjacent link 3 to the adjacent link. 3 tip bearing part 3
It is connected to B via a pivot shaft 8.

Note that the link 3 serving as the supporting end, that is, the first
In Fig. 2, the leftmost link 3 is the base side bearing part 3A.
is rotatably attached to the holding member 11 via a pivot shaft 12.

Therefore, the links 3, 3, except for the free end (the rightmost link 3 in FIGS. 1 and 2), are attached to the pivot shaft 8 on the grasping side of each joint. The grasping bars 4 are provided in relation to the pivot shafts 8 at appropriate intervals and parallel to each other.

The grasping bar 4 is made of a thin round bar, a flat bar, or a flat plate, and both ends of the gripping bar 4 are fixed to the pivot shafts 8 through support plate pieces, or the flat bar is shaped like a U-shape as shown in Figure 3. The pivot shaft 8 may be bent by bending the pivot shaft 8 and engaging the pivot shaft 8 using opposing pieces at both ends.
It is rotatably pivoted to the link 3, or fixed to the bearing section 3A of the link 3 that is closer to the free end of the adjacent links 3, 3, or to the bearing section 3B of another link 3.

Next, the grasping sheet 5 is made of a thin metal strip as described above, and after fixing one end to the tip of the link 3 at the leading edge of the multi-jointed body 2, that is, the free end, with a screw or the like, After passing through the space formed between the shaft 8 and the corresponding grasping bar 4 one after another to reach the support end side of the multi-section body 2, the other end is connected to a pneumatic valve attached to the holding member 11. It is connected to the working end of an actuator 6, such as a cylinder, so that it can pull the gripping sheet 5 toward the holding member 11 and relax it.

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

Further, the spring 7, which is an element member, is provided in association with the pivot shaft 8 at each of the nodes, and is mounted so as to exhibit elasticity in a direction that resists the force acting when the actuator 6 is gripped. It is necessary to do this, and both ends of the adjacent links 3, 3 are respectively locked to one bearing portion 3A and the other bearing portion 3B.

In the flexible grasping mechanism having such a structure, the grasping sheet 5 is connected to the grasping torque transmitting member for transmitting the torque of the actuator 6 to each link 3 while in contact with the individual grasping bars 4, 4. On the other hand, the springs 7, 7 provided on each pivot shaft 8 are formed as a release torque actuator that moves the grasping body 1 in the release direction opposite to the grasping direction.

In this flexible grasping mechanism, when the actuator 6 is actuated in the rod retraction direction, the grasping sheet 5 is pulled toward the holding member 11, and the multi-jointed bodies 2, 2 are moved as shown in FIG. When the rod is bent inward in the direction of the center line to wrap around the workpiece W and the actuator 6 is actuated in the direction of pushing out the rod, the restoring force of the spring 7 existing in each joint causes the multi-joint bodies 2, 2 to be are in a restored state in which they are each curled outward as shown in Figure 5.

Here, the mechanical principle for grasping the workpiece W with equal pressure from the surroundings by the grasping body 1 is as described in detail in Japanese Patent Publication No. 13874/1983, and grasping with equal pressure is as follows. It has been found that the grasping torque applied to the members of each link 3, 3 that come into contact with the workpiece W, that is, the grasping bars 4, 4, should be reduced in a quadratic manner along the axial length of the grasping 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 5 is brought into contact with the grasping bars 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 gripping bars 4, 4 is increased from the center of the pivot shaft 8 in each link 3, 3. It has a structure in which the distance (Rpi) to the closest point on the surface (refer to the back of Figure 2) gradually decreases from the supporting end to the free end.

By doing so, it is possible to make the contact pressure of each grasping bar 4, 4 uniform when grasping the workpiece W. Note that the degree of reduction in the grasping torque applied to the grasping bar 4 is not limited to a quadratic function, but a substantially similar result can be obtained even if it is expressed as a linear function.

Next, to explain the grasping operation by the above-mentioned grasping mechanism, when the actuator 6 is actuated to apply elasticity to the grasping sheet 5, each link 3, 3 overcomes the restoring elasticity by the springs 7, 7 and wraps the work W. In other words, it bends inward, and the second
The state shown in the figure reaches the state shown in the fourth figure.

As is clear from FIG. 4, when the workpiece W is grasped, the grasping sheet-like object 5 is moved by the grasping bar 4,
4, the situation is tense.

At this time, the link 3 and the grasping sheet-like object 5 can be considered to be equivalent to the state in which the sheet-like object 5 is fixed to the link 3, since each link 3, 3 is restrained in movement by the workpiece W. Therefore, at each connection point where each pivot shaft 8 exists, a torque (M=T・
Rpi (where T is elasticity) acts.

Here, the torque due to the grasping sheet-like material 5 is:
Since Rpi decreases in a quadratic manner from the supporting end side to the free end side, the distributed force acting on the workpiece W by the link 3 becomes uniform, and it is possible to grasp the workpiece W flexibly.

Next, when releasing the grip, the actuator 6 is operated in the opposite direction to reduce the tension of the gripping sheet 5, and the restoring elasticity of each spring 7 overcomes the link 3, 3. is work W
It moves away from the center and bends toward the outer periphery.

Then, the final posture shown in Figure 5 is obtained.
Here, since the distance (Rpi) of the grasping bar 4 to the pivot shaft 8 and the elasticity of the spring 7 at each pivot shaft 8 can be set to arbitrary values at the time of design,
It is also possible to operate the release side quickly to reduce loss time, while the grasping side can be operated lightly and slowly.

Although the grasping body 1 is shown in the second figure as being formed from a pair of multi-articulated bodies 2, 2, it is of course possible to use a mechanism for grasping with only one multi-articulated body 2.

Next, FIG. 3 shows another embodiment of the present invention, in which the spring 7 for generating release torque has a unique structure.

That is, the spring 7 provided at each node is formed from a pair of coil springs 7A and 7B having the same spring characteristics wound around the pivot shaft 8, and these are connected to the bearing portion of the link 3 near the free end. 3A and the bearing part 3B of the other link 3, and is wound around the cylindrical spacers 9, 9 which are loosely fitted to the pivot shaft 8. Both ends of the spring 7A are inserted and fixed into a stopper hole 13 provided at an appropriate position in the latter link 3 and a stopper hole 14 provided in a support plate piece that supports the grasping bar 4, while the other coil spring 7B is attached to the former link 7A. Both ends of the spring are inserted and fixed into a stopper hole 13 provided at an appropriate position on the link 3 and a stopper hole 14 provided in another support plate piece that supports the grasping bar 4.

In this case, it goes without saying that the grasping bar 4 should be rotatable around the pivot shaft 8 when it is pivoted on the pivot shaft 8.

With this structure, the two coil springs 7A, 7B are connected via the grasping bar 4, and the connected coil springs 7A, 7
It is clear from FIG. 3 that B is bridged between adjacent links 3, 3, and both links 3,
The coil springs 7A, which are present on both sides of the gripping bar 4, provide a releasing elasticity in a direction that resists the force acting on the gripping side of the actuator 6 to the gripping bar 4.
7B have the same spring characteristics, the same force acts on the support plate pieces on both sides of the grasping bar 4, so that the above-mentioned links 3, 3 located on both sides of the grasping bar 4 are The gripping force of the gripping sheet-like object 5 acting through the gripping bar 4 is such that the gripping force of the gripping sheet-like object 5 acting through the gripping bar 4 easily coincides with the normal direction to the surface of the workpiece W, thus making it possible to fix the grasping pin 4 to the surface of the workpiece W so as not to move it and to ensure reliable grasping.

The adjacent links 3, 3 and the grasping bar 4 can be easily engaged with each other by sequentially inserting the pivot shafts 8 and tightening them with the nuts 10, as shown by the two-dot chain line in FIG. It can be done.

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

(a) Since the thin plate-like link 3, grasping bar 4, and sheet-like object 5 are arranged so that the thickness direction and the radial direction are orthogonal to the movement axis for grasping and releasing, the structure is compact. It is possible to construct a hand with a thinner and simpler structure than the conventional structure using pulleys, and since the torque is transmitted by the sheet material 5, it is stronger than a wire. It can generate a strong grasping force.

(b) Since the distance of the grasping bar 4 from the pivot shaft 8 is not the same and can be changed arbitrarily at the time of design, it is possible to set the grasping torque to a different value, and it is possible to set the torque suitable for the purpose. .

(c) In addition, the spring 7 provided on the pivot shaft 8 of each joint is used to generate the torque for release (restoration).
Since the gripping mechanism is made of a material, the gripping mechanism can be made more compact and simple, and has the advantage that it can be made thinner.

[Brief explanation of drawings]

FIG. 1 is a front view showing essential parts according to one embodiment of the present invention, a front view taken along line II in FIG. 2, FIG. 2 is a plan view showing essential parts, and FIG. FIGS. 4 and 5 are plan views showing a grasping state and a releasing and restoring state according to an example of the present invention; FIGS. 6 to 8 are views showing conventional structures. Fig. 6 is a plan view showing the grasping state, Fig. 7 is an enlarged side view of a part of the multi-segmented body, and Fig. 8 is a BB line diagram of Fig. 7. 1...Grasp body, 2...Multi-segment body, 3...Link,
4... Bar for grasping, 5... Sheet-like object for grasping, 6
...Actuator, 7...Spring, 7A, 7B...
...Coil spring, 8...Pivot shaft.

Claims (1)

[Scope of Claims] 1. A large number of links 3, 3 are each supported at each node of a cord-like grasping body 1 formed from a multi-segment body 2 rotatably connected to each other, and In addition, grasping bars 4 are provided to maintain parallelism at the grasping side position, and one end of a grasping sheet-like material 5 is fixed to the free end of the multi-section body 2, and each section and a corresponding grasping bar 4 are provided. After sequentially passing through the space between the bar 4 and reaching the support end side of the multi-segment body 2, the other end is connected to an actuator 6 such as a cylinder to form a grasping torque transmission member, while each of the above-mentioned sections is the actuator 6
A release torque generating spring 7 having elasticity in the direction of resisting the acting force of the grasping sheet 5 is provided, respectively.
The gripping bar 4 is moved from the center of the pivot shaft 8 of each joint so that the gripping torque generated when the joints are brought into contact with each other decreases from the supporting end to the free end along the axial length of the multi-joint body 2. A flexible grasping mechanism characterized in that the distance (Rpi) to the contact surface of the grasping sheet-like object 5 gradually decreases from the supporting end toward the free end. 2. The grasping bar 4 is supported by the pivot shaft 8 and can be rotated therearound, while the release torque generating spring 7 is a coil connecting one link 3 and the grasping bar 4. The spring 7A and the coil spring 7B connecting the other link 3 and the grasping bar 4 are made of a pair of springs having the same spring characteristics and wound around the pivot shaft 8, and the grasping bar 4 is The flexible grasping mechanism according to claim 1, wherein the flexible grasping mechanism is formed so as to be able to be held at all times on a substantially equal dividing line of the angle formed by the links 3, 3 on both sides.