JPH0152157B2 - - Google Patents

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, etc., the action of grasping and holding an object is a common and important operation in performing various tasks with them. For this reason, various types of object grasping devices have been developed and used.

These devices appear to use devices based on various operating principles, but basically all of them are
There is no difference in that it is performed by a combination of separate devices of sensor and actuator. 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 faces of a sealed bellows-like elastic partition, and when this operation is performed,
The operation begins in response to a command issued based on detection information about the target object to be grasped from an external sensor.

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. The movement is similar in appearance to the trapping movement performed by so-called carnivorous plants; when an object enters a certain area, it senses the presence of that object and grabs it. It is an action.

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

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 in combination with 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.

That is, 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, the elastic partition to which the small holes are attached is a fixed partition. Then, a fluid pressure corresponding to the sum of the sizes of the gaps between the small hole and its opposing end face is 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. By this,
A conversion action can be performed 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 opening 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 perforated elastic partition provides 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 expands, 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 this kind of operation effectively, the pressure-displacement conversion ratio of the elastic partition wall with the end face provided with small holes (the ratio of the displacement of the movable end face to the pressure change introduced into the elastic partition wall) must be adjusted. is selected to be a value greater than a certain value corresponding to the conversion characteristics of the fluid circuit formed by the small holes and the aperture, assuming that the elastic partition wall provided with the small holes is a fixed wall. Bye. With this configuration, the positive feedback effect becomes effective, and when the total value of the gap between the movable end having the small hole and its opposing end surface becomes less than a certain value, the gap between the small hole and the aperture is reduced. 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 surfaces of the end surfaces 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 surfaces having the small holes. will be done.

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;
2, 3, and 4 are sectional views showing changes in the relative positions of the main movable parts to explain the operating state of the fluid grasping device shown in FIG. 1, and FIG. FIG. 7 is a cross-sectional view showing another embodiment.

In FIG. 1, fixed walls 1 and 2 each have bellow-like elastic partitions 3 and 4 attached thereto. One end of the elastic partition wall 3 is fixed to the fixed walls 1 and 2 at 5, and one end of the elastic partition wall 4 is fixed to the fixed walls 1 and 2 at 6, respectively. The other end of the elastic partition wall 3 and the other end of the elastic partition wall 4 are end faces 9 and 10 having small holes 7 and 8, respectively.
The shape of the end faces 9 and 10 is such that, due to the extension of the elastic partitions 3 and 4, when they come into contact with an object inserted between the end faces 9 and 10, the shapes of the end faces 9 and 10 are such that, when they come into contact with an object inserted between the end faces 9 and 10, they are similar to the opposing surfaces of the end faces 9 and 10 of the inserted object. The portions sealing the small holes 7 and 8 are shown in plan in FIG. 1, but may have other shapes. The chamber 11 inside the elastic partition wall 3 has an elastic partition wall 12, a branch pipe 15,
It communicates through 16, and also communicates with a fixed throttle opening 13 and through 13 with a fluid supply opening 14 from the outside.

When using this device, after the distance between the end faces 9 and 10 is set in advance according to the thickness of the object to be grasped, fluid at a constant pressure is supplied from the supply port 14 and the device enters the operating state. 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.
The chamber 11 inside the elastic partitions 3 and 4 is divided into 5 and 16.
and 12, and then flows out into the atmosphere through ports 7 and 8. Here, the diameter of the small openings 7 and 8 is the aperture opening 1.
3, and its fluid circuit resistance is sufficiently smaller than that of the throttle port 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.
The preset distance between the end faces 9 and 10 changes little, and the low constant pressure therefore changes little.

Next, consider a 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, and 19
is the surface of the object 17 facing the end surface 10.

In this case, the fluid that entered the chamber 11 from the branch pipe 15 passes through the opening 7 and flows out into the atmosphere from the gap between the end face 9 and the surface 18, and the fluid that entered the chamber 12 from the branch pipe 16 passes through the opening 8 between the end face 10 and the surface. It flows into the atmosphere through 19 gaps. The fluid circuit in this state is a so-called air micrometer with two detection nozzles,
Or, it is similar to a nozzle flapper mechanism, in which the pressure in the communicating chambers 11 and 12 corresponds to the sum of the gap between the end face 9 and its facing surface 18, and the clearance between the end face 10 and its facing surface 19. value. Since chambers 11 and 12 are in communication, their pressures are equal, so the pressure in chambers 11 and 12
Hereafter, the pressure of 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 approaches the surface 18 and the end face 1010 approaches the surface 19. As a result, these end faces 9 and surfaces 1
8 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 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 performed against the restoring elastic force based on Hook's law against the expansion of the elastic partition, but if the thickness of the object 7 is different from the end face 9 set before the actuation, 1
When the spacing is equal to or greater than a certain value with respect to the spacing of 0, the action of the positive feedback overcomes the restoring elastic force of the elastic partition wall, and the end face 9 becomes the surface 18 and the end face 10 becomes the surface 19 as shown in FIG. This leads to close contact. When such a close state occurs, air no longer flows out from the openings 7 and 8, so that the pressure in the chamber 11 increases to a constant high fluid pressure supplied from the supply opening 14. As a result, the elastic partition walls 3 and 4 try to expand further, and the end surfaces 9 and 10 push against the surfaces 18 and 19 of the object, respectively, resulting in equilibrium, and the end surface 1
9 and end surface 10 grasp and hold the object 17. In this case, the gripping force is proportional to the supply fluid pressure applied to the supply port 14, but the gripping force is proportional to the supply fluid pressure applied to the supply port 14.
It is related to the set interval between and 10, and the smaller this interval is, the larger it becomes.

The grasping operation of the object 7 by the end surfaces 9 and 10 as described above is performed when the thickness of the object 7 is less than the predetermined value with respect to the set interval between the end surfaces 9 and 10 before the operation. , is not performed when the thickness of the object 7 is smaller than the certain value. this is,
The movement of the end faces 9 and 10 in the direction of the surfaces 18 and 19 of the object due to the positive feedback action resists the elongation of the elastic partition before the end faces 9 and 18 and the end faces 10 and 19 come into close contact together. This is because the elastic force causes it to stop. That is, the end surfaces 9 and 10 come to rest at a position where the force based on the feedback action that moves the end surfaces 9 and 10 toward the object is exactly balanced by the elastic force that resists the extension of the elastic partition wall. FIG. 4 shows this state, in which the positions of the end faces 9 and 10 have moved toward the object from the positions 21 and 22 they occupied before the object was inserted, but no grasping operation is performed. As described above, when an object is inserted between the end surfaces 9 and 10, if the total value of the gap between the end surfaces 9 and 10 and the surface of the object facing each other before operation is equal to or greater than a certain value, it is detected. A grasping operation will be performed when no motion is performed and the value is below the certain value, which means that the grasping motion can be selectively performed. In other words, this selective operation is performed in which a grasping operation is performed for target objects whose thickness is above a certain value, and a grasping operation is not performed for target objects whose thickness is less than the specified value. It shows what the device can do.

In the state in which the grasping operation shown in FIG. 3 is being performed, the end surfaces 9 and 10 are displaced by stretching the elastic partitions 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 desired position is stopped by the surface of the object 7.

Therefore, if the device is 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, The force of contact between the end surfaces 9, 10 and the object in the gripping state, that is, the gripping force, is maintained sufficiently large, and the object 7 is held stably.

In FIG. 1, member 20 is an on-off valve that is always closed and is attached to release the grasping and holding state. When this opening/closing valve is opened in the grasped state shown in FIG. 3, the pressure in chamber 11 drops to atmospheric pressure, and the elastic partitions 3 and 4 contract, returning to their pre-operation state and allowing the end faces to open. 9 and 10 move away from 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, in Figure 1, bellows are used as the elastic partitions 3 and 4, but they may be replaced with elastic membranes made of rubber or metal alloys, which can be made flatter and therefore easier to install. There are cases where this is more convenient due to space considerations. 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. 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 grasping device of the present invention operates in accordance with a command from a sensor to another device from the outside, whereas conventional pneumatically operated or hydraulically operated grasping devices
It has the great advantage of not requiring the assistance of other devices because the sensor and grasping part work together. It is especially suitable for grasping, holding, and moving conductive plates made of soft materials such as paper, plastic, and rubber, and 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 increases to the supply pressure, so this pressure change can be used to confirm that the grasping operation has been performed. By guiding this pressure to a separate device, it can be controlled in synchronization with the grasping operation, so it has a wide range of applications as a component device for robots and manipulators.

Example: A device with the structure shown in Figure 1, with partition walls 3 and 4 having an outer diameter of 15 mm, a length of 15 mm, and a compliance
Two phosphor bronze bellows of the same shape with a pressure of 246 μm/N and a pressure-receiving area of 2.68 cm ² are used, small holes 7 and 8 are circular holes with an inner diameter of 2.5 mm, and an orifice with a diameter of 0.82 mm is used for the throttle port 13. Experiments were conducted by supplying constant air pressure of various magnitudes from 5 to 50 KPa from 14.
It was confirmed that grasping operations can be performed on pieces of paper, plastic, metal, etc. with the designed grasping force.

[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. Figure 5 shows
FIG. 7 is a cross-sectional view of a fluid grasping device that is 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, 11 and 12: chamber, 13: throttle opening,
14: supply port, 15 and 16: branch pipe, 17: object, 18 and 19: surface of object, 20: on-off valve,
21 and 22: End faces 9 and 1 before inserting the object
0 position.

Claims (1)

[Claims] 1. Two fixed walls facing each other with a certain distance apart are provided with chambers each having a stretchable elastic partition facing each other at intervals, and a A small hole is provided, and the opposing chambers are communicated via piping on the opposing rear end side,
Furthermore, the fluid grasping device is characterized in that this communication portion passes through one throttle port and is connected to a fluid supply port.