JPS62148181A - Fluid type gripper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that operates to grasp an object by detecting a change in fluid pressure caused by the presence of the object.

In robots, manipulators, and the like, the motion of grasping and holding an object is a common and important operation when performing various tasks with them. For this reason, various types of object grasping devices have been developed and used.

Although these devices may appear to be based on different operating principles, they are all basically operated by a combination of separate sensors and actuators. In other words, a sensor detects the existence and position of the object to be grasped and held, and according to that information a command is issued to a separate grasping device to drive it and grasp the object. can be thought of as a modification of the way humans look with their eyes and grasp them with their hands based on the observation results.

The operating principle and mode of operation of the present invention are different from those that take the process of grasping an object in general, and are characterized in that the device for grasping an object also serves as a sensor to detect the presence of the object. have

The power source of the present invention is fluid pressure. In general, the advantage of using fluid pressure to perform a grasping operation is that by changing the pressure, the grasping force can be relatively easily selected to a desired value, but conventional grasping devices that use fluid pressure ,
The target object is simply sandwiched between the movable end surfaces of a sealed bellow-like elastic bulkhead, and the operation is based on detection information about the target object from an external sensor. The operation begins in response to a command issued by the robot.

In the present invention, the grasping device does not operate in response to commands from a sensor installed separately, but the presence of the target object is detected by the function of a detection member that also serves as a mechanism for grasping the target object. Accordingly, the detection member itself extends to grasp and hold the target object. Its behavior is similar in appearance to the capturing behavior performed by so-called carnivorous plants; when an object enters a certain area, it senses the presence of that object and grabs it. be.

The gist of the present invention is to provide two fixed walls facing each other with a certain distance apart from each other, and to provide chambers each having an elastic partition wall that can be expanded and contracted at intervals to face each other. A small hole is provided in the facing end face of the fluid, and the facing chambers are connected to each other by piping at the facing rear end side, and further, this communicating part is connected to a fluid supply port through one throttle port. There is a fluid-operated gripping device, which

The operation of the present invention is based on a fluid circuit consisting of the aperture opening and two small holes provided at the movable ends of the two elastic partition walls, and the two small holes are connected to the two elastic partition walls, respectively. This operation is performed by combining a feedback mechanism formed by being provided at the movable end of the partition wall. This feedback mechanism is a positive feedback mechanism as opposed to the usual negative feedback mechanism.

In other words, the fluid circuit consisting of the aperture, two small holes, and their opposing end surfaces is a circuit similar to what is usually called a nozzle flapper system, and for example, an elastic partition with small holes attached is connected to a fixed partition. If this is the case, a fluid pressure corresponding to the sum of the sizes of the gaps between the small hole and its opposing end face will be generated in the chamber between the small hole and the aperture. Therefore, if one or both of the end faces facing the two small holes are displaced, the sum of the gaps will change, and a corresponding fluid pressure change will occur between the small hole and the aperture. , it is possible to perform a conversion action that converts the displacement of the end face facing the small hole into a pressure change in the chamber between the small hole and the aperture.

In the present invention, a part of the chamber between the two small holes and the aperture is formed by an elastic partition, and the small hole that performs the conversion action is formed at the movable end of the elastic partition.

By doing so, the elastic partition provided with small holes exerts a positive feedback effect on the fluid circuit. Specifically, when the end face facing one of the small holes approaches the small hole, the pressure in the chamber between the small hole and the aperture increases. As a result, the elastic partition provided with the openings stretches, the two openings are displaced in the direction of their opposing end faces, and the pressure in the chamber between the openings and the throttle opening increases. When the opposing end faces move away from each other, the opposite effect occurs.

In order to perform these operations effectively,
Pressure-displacement conversion rate (
The ratio of the displacement of the movable end surface to the pressure change introduced into the elastic partition) is the transformation of the fluid circuit formed by the small hole and the aperture when the elastic partition with the small hole is assumed to be a fixed wall. The value may be selected to be a certain value or more depending on the characteristics. With this configuration, the positive feedback effect becomes effective, and when the total value of the gap between the movable end with the small hole and its opposing end surface becomes less than a certain value, the gap between the small hole and the aperture The pressure in the chamber rises rapidly, and the small hole comes into close contact with the opposing end face.

In this case, the two outlets of the fluid from the small hole to the outside are blocked, so the pressure in the chamber between the small hole and the throttle port is transferred from the outside to the device through piping to the throttle port. With a force equal to and corresponding to the fluid pressure supplied through the oscilloscope, the two opposing end faces of the elastic septum in which the stoma is formed push against their respective opposite end faces. If the opposing end faces of the end faces having these two small holes constitute the front and back sides of an object inserted between the small holes, this object is held and grasped with a constant force by the end faces having the small holes. That will happen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fluid grasping device of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIGS. 2, 3, and 4 are main moving parts for explaining the operating state of the fluid gripping device shown in FIG. 1. A sectional view showing a change in relative position. FIG. 5 is a sectional view showing another embodiment of the present invention.

In Figure 1, the fixed walls (1) and (2) each have bellow-like elastic partitions (3) and (4).
is attached. One end of the elastic partition (3) is (5)
In (6), one end of the elastic partition (4) is fixed to the fixed walls (1) and (2), respectively. The other end of the elastic partition wall (3) and the other end of the elastic partition wall (4) have end faces (9), (
10). The shapes of the end faces (9) and (10) are
Due to the extension of the elastic partitions (3) and (4), the end face (9
) and (10) when it comes into contact with the object inserted between
The portions of the inserted object that form the facing surfaces of the end faces (9) and (10) are such as to seal the small holes (7) and (8), and are shown in plan in FIG. Other shapes are also possible. The inner chamber (11) of the elastic partition (3) communicates with the elastic partition (12) through branch pipes (15) and (16), and also communicates with a fixed throttle opening (13). through which it communicates with a fluid supply port (14) from the outside.

When using this device, the distance between the end surfaces (9) and (10) is set in advance according to the thickness of the object to be grasped, and then fluid at a constant pressure is supplied from the supply port (14) to bring it into operation. enter. Hereinafter, the state in which fluid pressure is not applied to the device from the supply port (14) will be referred to as the pre-operation state.

First, considering the case where there is no object between the end faces (9) and (10) of the device, the fluid supplied from the fluid supply port (14) in Fig. 1 passes through the throttle port (13) and enters the branch pipe. (15
) and (16), enters the chambers (11) and (12) inside the elastic partitions (3) and (4), and then enters the small opening (7) and (
8) into the atmosphere. Here, the small part (7) and (8)
The diameter of the aperture is made larger than that of the aperture (13), and its fluid circuit resistance is sufficiently smaller than that of the aperture (13). Therefore, the pressure in the chamber (11) and the chamber (12) communicating therewith is a constant low pressure close to the outside air.

The elastic partition walls (3) and (4) expand due to this pressure, but since the indoor pressure is minute, the amount of expansion is very small, and the preset distance between the end faces (9) and (10) is almost the same. does not change, and the low constant pressure therefore changes little.

Next, consider the case where an object (17) is inserted between the end faces (9) and (10) as shown in FIG. Here, (18) is the surface of the object (17) facing the end surface (9),
(19) is the surface of the object (17) facing the end face (10).

In this case, the fluid that entered the chamber (11) from the branch pipe (15) flows out into the atmosphere from the gap between the end face (9) and the surface (18) through the small opening (7), and flows out from the branch pipe (16) into the chamber (11). The fluid that has entered (12) flows from the small mouth (8) to the end face (10) and the surface (19).
) leaks into the atmosphere through gaps in the air. The fluid circuit in this state is similar to a so-called air micrometer with two detection nozzles or a nozzle flapper mechanism, and the pressure in the communicating chambers (11) and (12) is the same as that of the end face (9) and its opposing surface ( 12) and the gap between the end face (10) and its opposing surface (19). Since the chambers (11) and (12) communicate with each other, their pressures are equal, so the pressure in the chamber (11) will hereinafter be used to represent the pressures in the chambers (11) and (12). Since this pressure value is higher than the pressure in the chamber (11) before the object (7) is inserted, the elastic partitions (3) and (4) expand in proportion to the pressure, and the end face (9) 18), the end face (
10) approaches the surface (19). As a result, these end faces (
9) and the surface (18) and the gap between the end face (10) and the surface (19) both decrease, and the sum of these two gaps decreases accordingly. Therefore, the pressure in the chamber (11) increases in accordance with the reduced total value of the gap, further reducing the total value of the gap.

This effect is based on the positive feedback effect caused by the openings (7) and (8) being provided on the movable end faces of the elastic partitions (3) and (4), respectively. The displacement of the end faces (9) and (10) due to this action is carried out against the restoring elastic force based on Hooke's law against the expansion of the elastic bulkhead, but the thickness of the object (7) is When the distance between the end faces (9) and (10) is greater than a certain value, the positive feedback action overcomes the restoring elastic force of the elastic partition, and the end face (9) (18) and the end face (10) is the surface (1
9) and come close together as shown in Figure 3. When such a close state occurs, air no longer flows out from the small opening (7) and the small opening (8), so the pressure in the chamber (11) decreases to the same level as the supply opening (14).
) to a constant high fluid pressure supplied from As a result, the elastic partition walls (3) and (4) try to expand further, causing the surfaces (18) and (19) of the object to
10) are pushed and balanced, and the end face (9) and the end face (1
0) grasps and holds the object (17).

In this case, the gripping force is proportional to the supply fluid pressure applied to the supply port (14), but it is related to the set distance between the end faces (9) and (10) before actuation, and the smaller this distance is, the greater it becomes. .

The grasping operation for the object (7) by the end surfaces (9) and (10) as described above is performed when the thickness of the object (7) is the set interval between the end surfaces (9) and (10) before the operation. This is performed when the thickness of the object (7) is less than the certain value, and is not performed when the thickness of the object (7) is smaller than the certain value. This is because the end faces (9) and (10) are based on the positive feedback effect.
) in the direction of surfaces (18) and (19) of the object, the movement of the object in the direction of surfaces (18) and (19) causes the movement of
This is because the elastic force resisting the expansion of the elastic partition walls causes the elastic partition walls to stop before they come into close contact with each other. That is, the end surfaces (9) and (10) are moved at a position where the force based on the feedback action that moves the end surfaces (9) and (10) toward the object exactly balances the elastic force that resists the extension of the elastic partition. ) becomes stationary. Figure 4 shows this state, and although the positions of the end faces (9) and (10) have moved closer to the object than the positions (21) and (21) they occupied before the object was inserted, No grasping motion is performed. As mentioned above,
When an object is inserted between the end faces (9) and (10), the total value of the gap between the end faces (9) and the object surface facing each of the end faces (9) and (10) before operation is equal to or greater than a certain value. If so, the grasping operation will not be performed, and the grasping operation will be performed when the value is below the certain value, but this means that the grasping operation can be selectively performed. In other words, this selective operation is performed in which a grasping operation is performed for objects whose thickness is above a certain value, and a grasping operation is not performed for objects whose thickness is less than the specified value. Indicates what the device can do.

In the state in which the grasping operation shown in Fig. 3 is being performed, the end faces (1) and (10) extend to a length equal to the pressure conversion rate of the elastic partitions (3) and (4) multiplied by the fluid pressure applied to the supply port. It can be considered that the elastic partition wall is stopped by the surface of the object (7) where it should be extended and displaced.

Therefore, the device should be configured so that the length obtained by multiplying the pressure conversion rate by the fluid pressure is sufficiently larger than the set interval between the end faces (9) and (10) before the operation minus the width of the object. If this is done, the bonding force between the end surfaces (9), (10) and the object in the gripping state, that is, the gripping force, will be maintained sufficiently large, and the object (7) will be stably held.

In FIG. 1, the member (20) is an on-off valve that is always closed and is attached to release the grasping and holding state. When this on-off valve is opened in the gripping state shown in FIG. ) returns to the state before activation, and the end faces (9) and (10) become the object (17
) and the grasping state is released.

It should be noted that various modifications of the apparatus shown in FIG. 1 can be made by appropriate means. For example, bellows are used as the elastic partitions (3) and (4) in FIG.
This may be replaced with an elastic membrane made of rubber, metal alloy, etc., which can be made flatter, and may be more convenient in terms of installation space. In addition, in FIG. 4, two elastic thin films were used as elastic partition walls.

FIG. 3 is a cross-sectional view of another embodiment of the present invention. It should be noted that although each part of the apparatus shown in FIG. 4 has a different shape, members having the same function as each part in FIG. 1 are designated by the same numbers corresponding to those in FIG. 1.

The fluid-type grasping device of the present invention operates by integrating the sensor and the grasping part, whereas conventional pneumatically operated or hydraulically operated grasping devices are operated by a command from an external sensor of another device. This has the great advantage of not requiring the assistance of other devices. It is especially suitable for grasping, holding, and moving conductive plates made of soft materials such as paper, plastic, and rubber, but it has the advantage of being constructed with fewer parts than conventional methods. Another feature is that it can be used in narrow spaces where it would be difficult to use a separate sensor.

In addition, with this device, when grasping is performed, the pressure in the chamber between the aperture and the two small holes rapidly rises to the supply pressure, so this pressure change can be used to confirm that the grasping operation has been performed. Robots, such as being able to control pressure in synchronization with the grasping motion by guiding pressure to a separate device,
It has a wide range of applications as a component of manipulators.

Example: The device has the structure shown in Fig. 1, and the partition walls (3) and (4) have an outer diameter of 15 mm, a length of 15 mm, and a compliance of 2.
Use two phosphor bronze bellows of the same shape with a pressure receiving area of 2.68 cm2 and a pressure receiving area of 46 μm/N.
．． A circular hole of 5 mm and a diameter of 0.82 m at the aperture opening (13).
5 to 50 m orifice from the supply port (14)
Experiments were conducted by supplying constant air pressures of various KPa, and it was confirmed that grasping operations could be performed with the designed grasping force for plate pieces of paper, plastic, metal, etc.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fluid grasping device according to an embodiment of the present invention. 2, 3, and 4 are cross-sectional views showing changes in relative positions of main movable parts to explain the operating state of the device shown in FIG. 1. FIG. 5 is a sectional view of a fluid grasping device according to another embodiment of the present invention. 1 and 2: fixed wall, 3 and 4: elastic partition, 5 and 6: end of elastic partition, 7 and 8: small hole, 9 and 10: end surface, 1
1 and 12: chamber, 13: throttle opening, 14: supply port 15 and 16: branch pipe, 17: object, 18 and 19: surface of object, 20: opening/closing valve, 21 and 22: end surface before inserting the object 9 and 10 positions.

Claims (1)

[Claims] Two fixed walls facing each other with a certain distance apart are provided with chambers having expandable and contractible elastic partitions facing each other at intervals, and a small A fluid-type grasping device characterized in that a hole is provided, the facing chambers communicate with each other through piping at the facing rear end side, and further, this communicating part passes through one throttle port and is connected to a fluid supply port. .