JP7151990B2 - Gripper device - Google Patents

Description

The present invention relates to a gripper device utilizing a displacement-force transducer.

Conventionally, an Internally-Balanced Magnetic Unit has been proposed as a device that switches between the attraction and detachment of a permanent magnet with a small amount of energy when it is attracted to a magnetic material such as steel (for example, , Non-Patent Documents 1 or 2). This mechanism has a _nonlinear characteristic in which the attracting force _Fm of the permanent magnet increases sharply as it approaches the attracting surface _. It is something to do. In this mechanism, the internal force F _inter (=F _m −F _r ) of the permanent magnets is 0 regardless of the displacement, so the permanent magnets are always in a balanced state and no force is required to move the permanent magnets. In this mechanism, by bringing the permanent magnet into contact with the attracting surface, the reaction force _Fa of the nonlinear spring presses the entire mechanism against the target surface, so that the attracting state can be achieved. Further, by separating the permanent magnet from the attracting surface, the reaction force _Fa of the non-linear spring becomes smaller, so that the permanent magnet can be separated from the attracting surface. In this manner, the attracting state of the permanent magnet can be switched simply by moving the permanent magnet with a small force.

In Non-Patent Documents 1 and 2, in order to obtain a restoring force that compensates for the attracting force of the permanent magnet, a nonlinear spring having the opposite characteristic of the permanent magnet is used. As a configuration for obtaining this, a method using a non-circular pulley and a spring or a weight, a method adjusting the width and rigidity of a constant force spring for each displacement, a method using a cam or a link, etc. have been proposed. Specifically, non-circular pulleys are used in self-weight compensation for robot arms (see, for example, Non-Patent Document 3) and constant force springs for muscle training machines (see, for example, Patent Document 1). Also, as a structure similar to an inverse characteristic spring, a compound bow has been proposed in which the operation force is very small when the string is fully pulled (see, for example, Patent Document 2).

Hirose, Imazato, Kudo, Umetani, "Magnetic Attraction Unit with Internal Force Compensation", Journal of the Robotics Society of Japan, February 1985, Vol. 3, No. 1, p.10-19 Suzuki, Hirose, "Nonlinear Spring and Mechanism Design for Internal Force Compensating Magnetic Attraction Unit", Journal of the Robotics Society of Japan, May 2009, Vol. 27, No. 4, p.460-469 Endo, Yamada, Yajima, Ogata, Hirose, "Self-weight Compensation Mechanism with Non-Circular Pulley-Spring Type and Application to Four-bar Parallel Link Arm", Journal of the Robotics Society of Japan, January 2010, Vol. 28, No. 1 , p.77-84

U.S. Pat. No. 4,231,568 U.S. Pat. No. 3,486,495

The internal force compensation type magnetic attraction mechanism described in Non-Patent Documents 1 and 2 compensates for the attraction force of the permanent magnet with the restoring force of the non-linear spring, thereby moving the permanent magnet with a small amount of energy to achieve attraction and detachment. However, it did not convert the displacement (movement) of the permanent magnet into force. In addition to Non-Patent Documents 1 and 2, there has been nothing that converts displacement with very small energy into force.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gripper device that utilizes a displacement-force conversion device capable of converting displacement with very small energy into force. .

The present inventors expanded and generalized the principle of the internal force compensation type magnetic adsorption mechanism described in Non-Patent Documents 1 and 2, and as a result of further studies, arrived at the present invention. That is, a gripper device according to the present invention comprises a displacement-force conversion device having action means provided to apply a force to an object, support means for supporting the action means, and a pair of gripping members. and wherein the action means has an operation part provided so as to be able to change the magnitude of the force by reciprocating along the direction of the reaction force while receiving the reaction force of the force, The support means is connected to the operation part so as to apply to the operation part a force that balances the reaction force that changes with the movement of the operation part , one of the gripping members is made of the object, and the action is performed. The other gripping member is attached to the supporting means so as to be able to grip an object to be gripped between the gripping member and the gripping member. It is characterized in that it is arranged so as to face the one gripping member on the urging direction side of the gripping member.

The displacement-force conversion device according to the present invention can convert displacement into force according to the following principle. First, as shown in FIG. 1, an element "g(x)" corresponding to a permanent magnet and an element "-g(x)" corresponding to a nonlinear spring having the opposite characteristic are arranged in series. (x)” is acting on the object. Also, "-g(x)" is attached to the support on the side opposite "g(x)" so that it always balances "g(x)". Here, "g(x)" corresponds to the action means, and "-g(x)" and the support correspond to the support means. Also, the point of balance between "g(x)" and "-g(x)" corresponds to the operation section. Further, "-g(x)" having the inverse characteristic of "g(x)" means that the force acting on the operation unit due to "-g(x)" with respect to an arbitrary position of the operation unit is "g(x)" means that the magnitude of the force acting on the operation unit is the same, but the direction is opposite.

At this time, the operation unit, which is the balance point, can be reciprocated between "g(x)" and "-g(x)" with very little energy, and the displacement of the operation unit (predetermined It is possible to change the force acting on the object by "g(x)" depending on the movement distance from the position of . In this way, the displacement-force conversion device according to the present invention can convert the displacement of the operation section with very small energy into force acting on the object.

In the gripper device according to the present invention, it is preferable that the action means is provided so as to be able to apply a pulling force to the object. Preferably, the action means are linear springs, other elastic bodies, magnets, or the like. For example, the action means may be made of an elastic body that changes the force acting on both ends according to its length, one end of which is attached to the object, and the other end of which serves as the operation portion. Further, the action means may be composed of a magnet, one pole may be directed toward the object, and the other pole may have the operation portion.

Since the gripper device according to the present invention uses the displacement-force conversion device according to the present invention, a large gripping force can be generated between the pair of gripping members simply by moving the operating portion with very small energy. Obtainable.

According to the present invention, it is possible to provide a gripper device that utilizes a displacement-to-force conversion device capable of converting displacement with very small energy into force.

1 is a front view showing the principle of a displacement-force conversion device according to the present invention; FIG. 1 is a front view showing a displacement-force conversion device according to an embodiment of the present invention; FIG. FIG. 5 is a front view showing a modification of the displacement-force conversion device according to the embodiment of the present invention; It is a front view showing a gripper device of an embodiment of the invention. FIG. 5 is a front view showing a modified example for experiments of the displacement-force transducer of the embodiment of the present invention; 6 is a graph showing the relationship between the operating force and generated force with respect to the displacement of the operating portion of the displacement-force transducer shown in FIG. 5;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below based on the drawings.
2 and 3 show a displacement-to-force transducer according to an embodiment of the invention.
As shown in FIG. 2, the displacement-force conversion device 10 has action means 11 and support means 12 .

The means of action 11 consist of a linear spring with a varying force acting on its ends depending on its length. One end of the action means 11 is attached to the object 1 so as to apply a pulling force to the object 1 . Also, the action means 11 has an operation portion 11a at the other end. The operation part 11a receives a reaction force of the force acting on the object 1 and reciprocates along the direction of the reaction force, thereby changing the magnitude of the force acting on the object 1. FIG.

Support means 12 are provided to support the action means 11 . The support means 12 is connected to the operating portion 11a and applies a force to the operating portion 11a that balances the reaction force acting on the operating portion 11a. That is, the supporting means 12 has the opposite characteristic of the linear spring of the acting means 11, and acts on the operating portion 11a to balance the reaction force that changes with the movement of the operating portion 11a.

In a specific example shown in FIG. 2, the support means 12 has the reverse characteristic of the linear spring of the action means 11, and the reverse characteristic element 12a that changes the force acting on both ends according to the length, and the reverse characteristic element and a support 12b to which one end of 12a is connected. The other end of the reverse characteristic element 12a of the support means 12 is connected to the operation portion 11a, and a force that balances the reaction force acting on the operation portion 11a can be applied to the operation portion 11a.

Note that the support means 12 may have any configuration as long as it has the reverse characteristics of a linear spring. or a weight, a configuration in which the width and rigidity of a constant force spring are adjusted for each displacement, a configuration in which a cam or a link is used, or the like.

Next, the action will be described.
As shown in FIG. 2, in the displacement-force conversion device 10, when the operating portion 11a is moved to the action means 11 side, the force acting on the object 1 is reduced, and the operating portion 11a is moved to the support means 12 side. When moved, the force acting on the object 1 increases. At this time, since the operating portion 11a is a balance point between the linear spring of the acting means 11 and the reverse characteristic element 12a of the supporting means 12, the operating portion 11a can be reciprocated with a very small force. Further, since a linear spring is used as the action means 11, there is a linear relationship between the displacement of the operation part 11a from the position where the force acting on the object 1 is zero and the force acting on the object 1. relationship is obtained. In this manner, the displacement-force conversion device 10 can convert the displacement of the operating portion 11a by very small energy into a force acting on the object 1. FIG.

As shown in FIG. 3, in the displacement-force conversion device 10, the action means 11 is made of a permanent magnet, one pole is directed toward the object 1, and the other pole has an operation portion 11a. may The inverse characteristic element 12 a of the support means 12 then has the characteristic of a non-linear spring having the inverse characteristic of the permanent magnet of the action means 11 . In this case as well, the operation portion 11a can be reciprocated with a very small force, and the displacement of the operation portion 11a can be converted into a force acting on the object 1. FIG.

FIG. 4 shows a gripper device according to an embodiment of the invention.
As shown in FIG. 4, the gripper device 20 has the displacement-force conversion device 10 shown in FIG. 2 and a pair of gripping members 21,22.

The displacement-force conversion device 10 has a frame-shaped support 12b, and an action means 11, an operation portion 11a, and an inverse characteristic element 12a are arranged inside. In the displacement-force conversion device 10, one end of the action means 11 passes through a through hole 12c provided in the frame-like support 12b and extends to the outside of the support 12b.

The displacement-force conversion device 10 also has a first feed screw 15 , a first motor 16 and a nut 17 . The first feed screw 15 is arranged inside the support 12b, and one end thereof is attached to the support 12b so as to extend along the moving direction of the operating portion 11a. The first motor 16 is attached to the outside of the support 12b so as to rotate the first feed screw 15. As shown in FIG. The nut 17 is screwed onto the first feed screw 15, and the operating portion 11a is attached thereto. By rotating the first feed screw 15 with the first motor 16 , the displacement-force conversion device 10 can reciprocate the operating portion 11 a along the first feed screw 15 via the nut 17 .

One gripping member 21 has an elongated plate shape, one end of which is attached to one end of the action means 11, and a first gripping surface 21a on the surface of the other end. One of the gripping members 21 is urged in the direction in which the acting means 11 is pulled by the force acting from the acting means 11 . One gripping member 21 corresponds to the object 1 in FIG.

The other gripping member 22 has a second feed screw 22a, an elongated gripping plate 22b, a second motor 22c and a nut 22d. The second feed screw 22a is arranged outside the support 12b along the moving direction of the operating portion 11a. The gripping plate 22b has a second gripping surface 22e on the surface of one end, and is arranged so that the second gripping surface 22e faces the first gripping surface 21a on the urging direction side of the gripping member 21 on one side. ing. One end of the second feed screw 22a is attached to one end of the gripping plate 22b. The second motor 22c is attached to the surface of the grip plate 22b opposite to the second feed screw 22a so as to rotate the second feed screw 22a. The nut 22d is screwed onto the second feed screw 22a and attached to the support 12b. Thereby, one end of the gripping plate 22b is attached to the support 12b via the second feed screw 22a and the nut 22d. The gripping plate 22b of the other gripping member 22 can be reciprocated with respect to the support 12b along the urging direction of the gripping member 21 by rotating the second feed screw 22a by the second motor 22c. It's becoming

The displacement-force conversion device 10 can grip the object 2 between the first gripping surface 21a and the second gripping surface 22e. When gripping the gripped object 2, the displacement-force conversion device 10 can adjust the position of the other gripping member 22 with the second feed screw 22a and adjust the gripping force with the first feed screw 15. ing.

Next, the action will be described.
Since the gripper device 20 uses the displacement-force conversion device 10, a large gripping force can be obtained between the pair of gripping members 21 and 22 simply by moving the operating portion 11a with very small energy. can be done. Also, the magnitude of the gripping force can be adjusted.

The gripper device 20 has a configuration in which the displacement-force conversion device 10 that controls the gripping force by the first feed screw 15 and the high-speed positioning mechanism for the gripped object 2 by the second feed screw 22a are arranged in series. ing. The gripper device 20 adjusts the position of the gripping plate 22b by the second feed screw 22a so that the one gripping member 21 can be moved by the biasing force acting from the action means 11, and the support 12b and the one gripping member 21, 22 ("b" in FIG. 4), the gripping force is adjusted by the first feed screw 15, and the gripped object 2 is positioned between the first gripping surface 21a and the second gripping surface 22e. can be grasped.

The gripper device 20 can be positioned at high speed by the second feed screw 22a, but has back drivability, so there is a possibility that reverse rotation will occur when the gripping force increases. Therefore, as shown in FIG. 4, a torque diode 23 may be used to release reverse rotation torque to the frame. Also, a mechanism having the same component as the torque diode 23 may be provided in the direct acting portion.

As described above, the displacement-force conversion device 10 can be used in the gripper device 20 shown in FIG. It can also be used for a switching mechanism capable of switching physical quantities, a brake mechanism, a pressure regulating valve mechanism using a spring in its internal structure, and the like.

An experiment was conducted using the displacement-force conversion device 10 shown in FIG. As shown in FIG. 5, the displacement-force conversion device 10 uses a linear spring consisting of a tension spring as the action means 11, and as the support means 12, a non-circular pulley 31, a circular pulley 32, and a weight 33 according to Non-Patent Document 3. and A non-circular pulley 31 is connected with a circular pulley 32 to convert the angle of rotation into displacement of a linear spring. The non-circular pulley 31 has a shape in which the angle θ is proportional to the radius r, and is provided so that θ is in the range of 0° to 345° and r is 10 to 40 mm. Thereby, the support means 12 converts the load mg generated by the weight 33 (mass: m) into the reverse characteristic of a linear spring by the non-circular pulley 31 . Moreover, the weight 33 was 1.27 kg.

In the experiment, the balance point between the action means 11 and the support means 12 was set to b=0 mm, and the operation part 11a, which is the balance point, was moved. ), the values of the force (operating force) for moving the operating portion 11a and the force (generated force) acting on the object 1 were measured. Further, when the linear spring of the action means 11 is stretched by 10 mm in advance and the operation part 11a, which is the balance point, is shifted by 10 mm (b=10 mm), and when the linear spring of the action means 11 is stretched by 20 mm in advance and balanced. The values of the operating force and the force generated with respect to the displacement of each operating portion 11a were also measured when the operating portion 11a, which is a point, was shifted by 20 mm (b=20 mm). The operating force was measured using a force gauge constrained by a linear guide, and the generated force was measured by a load cell attached to one end of a linear spring. Note that b corresponds to "b" in FIG. The measurement results are shown in FIG.

As shown in FIG. 6, it was confirmed that the operating portion 11a could be moved with a very small force compared to the generated force. Further, it was confirmed that as the displacement of the operating portion 11a increased, the generated force also increased, while the operating force hardly changed and remained small. For example, when b = 0, 10, and 20 mm, it was confirmed that the operating portion 11a could be moved with a force of about 0.8%, 11%, and 20% of the generated force, respectively, and the generated force could be controlled. . From this, it can be seen that the smaller b is, the smaller the operating force can be. Further, since the force required to move the operating portion 11a is substantially constant, it can be seen that control by a motor or the like is easy.

1 object 2 object to be grasped

REFERENCE SIGNS LIST 10 displacement-force transducer 11 action means 11a operating part 12 support means 12a reverse characteristic element 12b support

12c through hole 15 first feed screw 16 first motor 17 nut

20 gripper device 21 (one) gripping member 21a first gripping surface 22 (other) gripping member 22a second feed screw 22b gripping plate 22c second motor 22d nut 22e second gripping surface 23 torque diode

31 non-circular pulley 32 circular pulley 33 weight

Claims (4)

a displacement-to-force conversion device having an action means capable of applying a force to an object and a support means for supporting the action means;
a pair of gripping members ;
The action means has an operation part that is applied with a reaction force of the force and that reciprocates along the direction of the reaction force so as to be able to change the magnitude of the force,
the support means is connected to the operation portion so as to apply a force to the operation portion that balances the reaction force that changes with movement of the operation portion ;
one gripping member comprises the object and is urged in a predetermined direction by the force acting from the action means;
The other gripping member is attached to the support means, and is opposed to the one gripping member on the urging direction side of the one gripping member so as to be able to grip an object to be gripped between the gripping member and the one gripping member. that it is placed
A gripper device characterized by: 2. The gripper device according to claim 1, wherein said action means is provided so as to apply a pulling force to said object. The action means is composed of an elastic body that changes the force acting on both ends according to its length, and has one end attached to the object and the other end serving as the operating portion. 3. Gripper device according to claim 1 or 2. 3. The gripper device according to claim 1, wherein said acting means comprises a magnet having one pole directed toward said object and having said operating portion on the other pole.

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