END EFFECTOR, END-EFFECTOR SET, AND CONTROL SYSTEM

An end effector includes a hole plate includes a plurality of holes, a plurality of pins that respectively penetrate the plurality of holes and are hung on the hole plate to be movable upward, and a force applying part that applies an inward force to an outer pin of the plurality of pins.

BACKGROUND

1. Technical Field

The present disclosure relates to an end effector, an end-effector set, and a control system.

2. Description of the Related Art

Patent Literature (PTL) 1 describes a robot hand including an attracting part such as an electromagnet that attracts a workpiece and a conforming part including six or more pins that are lowered by their own weight to conform the shape of the workpiece. The robot hand fixes the ascending or descending pins as necessary and fixes the workpiece using a support hook that supports the workpiece from below as necessary when, for example, the workpiece has a large weight.

SUMMARY

The present disclosure has been devised in view of the above-mentioned conventional situation and has as its object to provide an end effector that can support a target object (for example, a workpiece).

An end effector according to one aspect of the present disclosure includes a hole plate includes a plurality of holes, a plurality of pins which respectively penetrate the plurality of holes and are hung on the hole plate to be movable upward, and a force applying part that applies an inward force to an outer pin of the plurality of pins.

This makes it possible to further move a plurality of pins inwardly by the force applying part while the target object is surrounded by the pins. Moving the pins inwardly in this manner enables the end effector to support a target object (for example, a workpiece).

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings as appropriate. It is noted that a more detailed description than necessary may be omitted. For example, the detailed description of already well-known matters and overlapping description of substantially the same configurations may be omitted. This is to avoid an unnecessarily redundant description below and to facilitate understanding of a person skilled in the art. Note that the attached drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter as described in the appended claims.

First Exemplary Embodiment

FIG. 1is a perspective view illustrating an example of a configuration of end effector10according to a first exemplary embodiment.

Robot devices used in factories and the like can perform various operations by attaching end effector10to a robot arm (not illustrated). For example, the robot arm picks a target object (workpiece or the like) flowing through a production line in a factory using end effector10and conveys the object to a destination. With this configuration, even when the pins are usually thin and it is difficult to attach a sensor to each pin itself, the support state of target object3can be determined. In addition, the next processing can be automatically started by using the determination itself of whether target object3is supported as a trigger. The target object may be a relatively small object such as a screw, a nut, or a washer, or may be a relatively large object (for example, a housing) such as a rib or a boss.

FIG. 2is a longitudinal sectional view illustrating an example of the configuration of end effector10according to the first exemplary embodiment. Note that, in the present disclosure, the same direction as gravity will be referred to as downward, and the direction opposite to gravity will be referred to as upward. In the present disclosure, a cross section parallel to the direction of gravity is described as a longitudinal cross section, and a cross section perpendicular to the direction of gravity is described as a transverse cross section.

FIG. 2illustrates the state of end effector10at a stage (hereinafter referred to as a “standby stage”) before end effector10connected to the robot arm starts picking target object3. The configuration of end effector10will be described below with reference toFIG. 2.

Hole plate11is a plate provided with a plurality of through holes. The thickness of hole plate11may be, for example, 0.1 mm to 2 mm. However, the present invention is not limited to this. Hole plate11may be integrated with base13.

Each pin12has an elongated rod shape and is inserted into each hole of hole plate11. The cross-sectional shape of pin12and the shape of the hole may be circular, but are not limited to this. The diameter of pin12may be, for example, between 0.1 mm and 2 mm, and is slightly smaller than the diameter of the hole. The material of pin12may be a metal. However, the material of pin12is not limited to metals, and may be, for example, a resin.

Pin12has, at its upper end, a head portion having a diameter larger than the diameter of the hole provided in hole plate11. The head portion serves as a stopper, and pin12is hung from hole plate11by its own weight. In addition, since the diameter of pin12is slightly smaller than the diameter of the hole, pin12can move upward when pushed up from below. In this case, the thickness of hole plate11is sufficiently short with respect to the length of pin12. Accordingly, pin12is movable within a conical range having the hole as a vertex. That is, pin12has some backlash. Accordingly, as will be described later, target object3can be supported by pins12.

The lower portion of pin12has a tapered shape that narrows toward the lower end. That is, the lower end of pin12has a pointed shape like a needle. Accordingly, as will be described later, this makes it possible to support target objects3in various shapes.

The maximum movable radius (for example, the radius of the bottom surface of the cone formed by the movable range having the above hole as a vertex) due to the backlash of pin12may be within the distance from the center of pin12to the center of adjacent pin12. This is because the force transmission efficiency decreases when pin12moves beyond the center of adjacent pin12.

Outer pin12A may be shorter than inner pin12B. As a result, as will be described later, the force applied inward to outer pin12A (that is, the force toward target object3) is transmitted not to the lower end of inner pin12B but to an appropriate side surface of inner pin12B, thereby increasing the force for supporting target object3.

Base13has a tubular shape. The upper surface of base13is connected to the robot arm. Hole plate11is fixed to the lower surface of base13. Therefore, the plurality of pins12hanging from hole plate11protrude lower than the lower surface of base13.

Holder14has a tubular shape and surrounds the outside of the plurality of pins12. Holder14includes side surface portion14A forming a surface substantially parallel to pin12and projection14B protruding toward the inside of the cylinder. In this example, projection14B is one aspect of the force applying part.

Movable plate15is provided above hole plate11and can move up and down. Movable plate15is coupled to slit14C provided in an upper portion of side surface portion14A of holder14. When movable plate15ascends, it comes into contact with the upper end portion of slit14C. When movable plate15further ascends, holder14is lifted upward. Further, movable plate15pushes down inner pin12B protruding above hole plate11when lowering.

Actuator16is a device that raises, lowers, and stops movable plate15. Actuator16may be, for example, an air actuator, and lowers and raises movable plate15by sucking and discharging air.

FIG. 3is a longitudinal sectional view illustrating an example of the state of end effector10in a tracing stage.

When shifting from the standby stage to the tracing stage, the robot arm lowers end effector10toward placed target object3and presses the tips of pins12against target object3. That is, the shape of target object3is traced by the plurality of pins12. In this tracing, since pin12touching the surface of target object3cannot be lowered any more, the upper portion of pin12protrudes above hole plate11. For example, the robot arm lowers end effector10until at least some of inner pins12B among the plurality of inner pins12B touch the placement surface of target object3. Thus, end effector10can trace the shape of target object3by the plurality of inner pins12B. Note that end effector10may be lowered manually or automatically.

Note that end effector10may generate vibration in the tracing stage. Since pin12that has been caught halfway and has not been completely lowered can be lowered by this vibration, more accurate tracing can be performed. Therefore, in the support stage described later, the transmission efficiency of the force between adjacent pins12and the transmission efficiency of the force to target object3can be improved.

FIG. 4is a longitudinal sectional view illustrating an example of the state of end effector10in the support stage.

Upon transition from the tracing stage to the supporting stage, actuator16raises movable plate15(see the upward arrows from movable plate15). As a result, holder14coupled to movable plate15is raised, and projection14B of holder14comes into contact with the side surface of outer pin12A to apply an inward force to outer pin12A (that is, a force toward target object3). Due to this inward force, as outer pin12A falls inward, inner pin12B also sequentially falls inward (the rightward arrow on inner pin12B), and inner pin12B finally coming into contact with target object3is pressed against the side surface of target object3. In this manner, target object3is supported by the plurality of inner pins12B in contact with target object3. Note that a mechanism that applies inward force (that is, force toward target object3) to outer pin12A by the mechanism as described above is one aspect of the force applying part. For example, projection14B described above is one aspect of the force applying part. However, the force applying part may be configured by means other than projection14B.

The robot arm conveys target object3to a destination while end effector10supports target object3in this manner.

FIG. 5is an enlarged view of a portion including projection14B of an example of the configuration of end effector10. As illustrated inFIG. 5, when holder14is raised, projection14B comes into contact with outer pin12A and falls inward. Inner pin12B falls inward by being pushed by outer pin12A, and the side surface portion of inner pin12B comes into contact with target object3from the lateral direction illustrated inFIG. 5. That is, a lateral force is applied to target object3. Applying a force from the opposite side to this lateral force so as to face each other makes it possible to support target object3so as to grip target object3.

Note that the lower portion of pin12has a tapered shape that narrows toward the lower end. As a result, as compared with a case where the lower portion of pin12has a simple rod shape, the side surface portion of inner pin12B that has fallen inward comes into contact with target object3more smoothly. Therefore, a lateral force is easily applied to target object3, and the support of target object3is stabilized.

FIG. 6is a longitudinal sectional view illustrating an example of the state of end effector10in the pushing stage.

Upon transition from the support stage to the pushing stage, actuator16lowers movable plate15to the lowest point. As a result, holder14coupled to movable plate15is lowered, and projection14B of holder14does not come into contact with outer pin12A to release the inward force applied outer pin12A. Accordingly, since the inward force of inner pin12B in contact with target object3is also released, no lateral force is applied to target object3. As a result, target object3is not supported.

In addition, since inner pins12B protruding above hole plate11are pushed down as movable plate15is lowered, target object3is pushed downward by inner pins12B. As a result, target object3is pushed out from end effector10. Pushed target object3falls, for example, into a container or the like provided in the next process on the production line.

FIG. 7is a transverse sectional view illustrating an example of the configuration of end effector10according to the first exemplary embodiment. The arrangement of the plurality of holes of hole plate11is a staggered arrangement. Accordingly, the plurality of pins12hanging from hole plate11are also arranged in a staggered arrangement as illustrated inFIG. 7. The gap between adjacent pins12in the staggered arrangement may be, for example, smaller than the diameter of pin12.

The staggered arrangement formed by the plurality of holes and the plurality of pins12of hole plate11forms a plurality of regular hexagons. First, outermost pins12A among the plurality of pins12form the sides of a regular hexagon. Pins12B on the inner side of outermost pins12A also form the sides of a regular hexagon. That is, the staggered arrangement is configured such that a plurality of regular hexagons having different sizes overlap each other. By arranging the plurality of pins in this manner, the force applied inward with respect to outer pins12A (that is, the force toward target object3) is efficiently transmitted to inner pins12B, thereby stably supporting target object3.

The arrangement of the plurality of holes of hole plate11and the arrangement of the plurality of pins12may be other arrangements. The staggered arrangement formed by the plurality of holes and the plurality of pins12of hole plate11may form a plurality of regular triangles.

<Configuration of Control System>

FIG. 8is a block diagram illustrating an example of a hardware configuration of control system100according to the first exemplary embodiment. Control system100controls the operation of end effector10described above. Note that control system100may further control a robot arm (not illustrated). Control system100may be provided inside the robot arm or may be provided outside the robot arm.

Control system100includes processor101, memory102, input device103, end effector connection part105, communication device106, and input and output interface107. Memory102, input device103, end effector connection part105, communication device106, and input and output interface107are each connected to processor101by an internal bus or the like so as to be capable of inputting and outputting data or information.

Processor101functions as the controller of control system100. For example, processor101performs control processing for comprehensively controlling operation of each part of control system100, input and output processing of data or information with each part of control system100, data calculation processing, and data or information storage processing. Processor101functions also as a controller that controls end effector10and the robot arm. For example, processor101controls the operations of end effector10and the robot arm in the standby stage, the tracing stage, the support stage, and the pushing stage described above. Processor101may be a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP), or a field programmable gate array (FPGA).

Memory102stores various programs (an operating system (OS), application software, etc.) to be executed by processor101, and various data. Memory102includes, for example, a hard disk drive (HDD), a flash memory, a read only memory (ROM), and/or a random access memory (RAM).

Input device103has a function as a human interface for a user and receives a manipulation input from the user. In other words, input device103is used for giving an input or an instruction for various processes performed by control system100. An example of input device103is a keyboard or a mouse. Alternatively, input device103is a programming pendant connected to the controller (not illustrated) of the robot arm.

End effector connection part105is a device for connecting end effector10to control system100. End effector connection part105and end effector10are connected by a wire such as a connector and a cable. However, end effector connection part105and end effector10may be wirelessly connected.

Communication device106is a device for communicating with the outside via network108. This communication may be wired communication or wireless communication.

Input and output interface107has a function as an interface through which data or information is input or output from or to control system100.

Note that the configuration of control system100illustrated inFIG. 8is an example, and control system100may not include some of the components illustrated inFIG. 8or may further include additional constituent elements not illustrated inFIG. 8.

The configuration of end effector10is not limited to the above configuration. For example, projection14B of holder14may be formed of an air tube, and the air tube may be disposed above the lower end of outer pin12A. In this case, end effector10injects air into the air tube in the support stage. As a result, the air tube expanded by the injection of air presses outer pin12A from the side surface and applies an inward force (that is, a force toward target object3) to outer pin12A. Due to this inward force, as outer pin12A falls inward, inner pin12B also sequentially falls inward, and inner pin12B finally coming into contact with target object3is pressed against the side surface of target object3. Even with such a configuration, end effector10can support target object3. The air tube is an aspect of the force applying part.

Alternatively, end effector10may be configured not to include holder14but to include outer pin12A made of a shape memory alloy whose tip portion is deformed inward (that is, toward target object3) when energized. In this case, end effector10energizes outer pin12A in the support stage. Accordingly, as outer pin12A is deformed inward, inner pin12B also sequentially falls inward, and inner pin12B finally coming into contact with target object3is pressed against the side surface of target object3. Even with such a configuration, end effector10can support target object3. A device that energizes outer pin12A is an aspect of the force applying part.

Second Exemplary Embodiment

A second exemplary embodiment will exemplify end effector10that supports a switching adapter. In the above first exemplary embodiment, target object3supported by end effector10is, for example, a workpiece to be picked in a factory or the like. On the other hand, in the second exemplary embodiment, end effector10supports another end effector. As an example of such another end effector, switching adapter33described later is available. End effector10and the other end effector supported and used by end effector10are collectively referred to as a set of end effectors.

The following will describe end effector10that supports and uses switching adapter33including suction pad32capable of sucking target object3. Note that, in the second exemplary embodiment, constituent elements common to those in the first exemplary embodiment are denoted by common reference numerals, and descriptions thereof may be omitted.

FIG. 9is a longitudinal sectional view illustrating an example of the configuration of end effector10according to the second exemplary embodiment.

Main body suction unit31is mounted on end effector10in addition to the constituent elements described inFIG. 2. Main body suction unit31can be coupled to suction pad32described with reference toFIG. 10and constitutes a path for sucking and discharging air with respect to coupled suction pad32.

When actuator16sucks and discharges air, main body suction unit31may be connected to an air conveyance system common to actuator16.

FIG. 10is a longitudinal sectional view illustrating an example of the tracing stage of switching adapter33by end effector10according to the second exemplary embodiment.FIG. 11is a longitudinal sectional view illustrating an example of the support stage of switching adapter33by end effector10according to the second exemplary embodiment.

As illustrated inFIG. 10, switching adapter33includes suction pad32. Pipe34for sucking and discharging air into and from the suction pad is coupled to main body suction unit31. This forms a path for sucking and discharging air from suction pad32to main body suction unit31.

As a result, end effector10can use suction pad32through supported switching adapter33. That is, the robot arm can use another type of end effector such as suction pad32through switching adapter33without replacing pin-shaped end effector10according to the present disclosure.

The other type of end effector mounted on switching adapter33is not limited to suction pad32described above. For example, a finger type, electromagnetic type, or jamming type end effector may be mounted on switching adapter33.

Third Exemplary Embodiment

A third exemplary embodiment will exemplify end effector30that determines whether or not target object3can be supported in the support stage. Note that, in the third exemplary embodiment, constituent elements common to those in the first exemplary embodiment are denoted by common reference numerals, and descriptions thereof may be omitted.

An example of a method for determining whether or not end effector30according to the third exemplary embodiment can support target object3in the support stage will be described with reference toFIGS. 12 and 13.FIG. 12illustrates a state in which pins12protrude in the space between hole plate11and movable plate15(hereinafter referred to as “base inner space”) when target object3can be supported.FIG. 13illustrates a state in which pins12protrude in the space inside the base when target object3cannot be supported.

End effector30according to the third exemplary embodiment includes imaging device17(for example, a 3D sensor) for imaging the protruding state of pins12in the space inside the base in addition to the components of end effector10according to the first exemplary embodiment. Note that imaging device17may be provided anywhere as long as it can image the space inside the base. In the support stage, for example, as illustrated inFIG. 13, imaging device17captures an image of protruding state201aof pins12in the space inside the base to generate three dimensional (3D) sensor image201b. Processor101of control system130then specifies three-dimensional shape201indicating protruding state201aof the plurality of pins12from 3D sensor image201bacquired by imaging device17. Processor101compares specified three-dimensional shape201with reference three-dimensional shape200indicating protruding state200aof the plurality of pins12when target object3can be supported as illustrated inFIG. 12to determine whether or not end effector30can support target object3. In this case, reference three-dimensional shape200is identified from 3D sensor image200bacquired by imaging device17by capturing an image of protruding state200aof the plurality of pins12when target object3as illustrated inFIG. 12can be supported. For example, the comparison between three-dimensional shape201illustrated inFIG. 13and reference three-dimensional shape200illustrated inFIG. 12indicates that the right peak of the two peaks is low, and the inclined portion at the right end is missing. That is, the matching degree of three-dimensional shape201with respect to reference three-dimensional shape200is low (for example, the matching degree is less than a predetermined threshold). Accordingly, processor101may determine from three-dimensional shape201illustrated inFIG. 13that target object3cannot be supported.

When the height of a peak of three-dimensional shape201is less than a predetermined value, processor101may determine that target object3is not supported. When the inclination angle from the skirt to the peak of three-dimensional shape201is less than a predetermined angle (that is, when the inclination from the foot to the peak is gentle), processor101may determine that target object3is not supported. This is because in these cases, the area of each pin12in contact with the side surface of target object3is insufficient (for example, the lower end of pin12is in contact with target object3, but the portion above the lower end of pin12is not in contact with target object3), and there is a high possibility that end effector10cannot lift target object3.

With this configuration, even when the pins are usually thin and it is difficult to attach a sensor to each pin itself, the support state of target object3can be determined. In addition, the next processing can be automatically started by using the determination itself of whether target object3is supported as a trigger. If it is determined that end effector10has not been able to support target object3, it is possible to perform processing such as redoing the tracing stage or the support stage, or notifying of an alert. When it is determined that end effector30can support target object3, target object3can also be moved to the next work place.

FIG. 14is a block diagram illustrating an example of the hardware configuration of control system130according to the third exemplary embodiment. Note that, in the description with reference toFIG. 14, constituent elements common to those inFIG. 8are denoted by common reference numerals, and descriptions thereof will be omitted.

Control system130includes image acquisition unit104in addition to the constituent elements illustrated inFIG. 8.

Imaging device17described above is connected to image acquisition unit104wiredly or wirelessly. Image acquisition unit104then acquires an image captured by imaging device17. Processor101performs various types of image processing on the image acquired by image acquisition unit104. Note that control system130may further include an image processing unit (not illustrated), and in this case, the image processing unit may perform various types of image processing under the control of processor101.

As described above, end effector10according to an aspect of the present disclosure includes hole plate11provided with the plurality of holes, the plurality of pins12which respectively penetrate the plurality of holes and are hung on hole plate11so as to be movable upward, and the force applying part (for example, projection14B) that applies an inward force to outer pin12A among the plurality of pins12. As a result, when the force applying part applies an inward force (that is, a force toward target object3) to outer pins12A, outer pins12A fall inward, and accordingly, inner pins12B sequentially fall inward, and inner pins12B finally coming into contact with target object3can support target object3.

Further, the arrangement of the plurality of holes is a staggered arrangement and may form a hexagonal shape. As a result, the inward force applied to outer pin12A is efficiently transmitted by inner pin12B, so that the force for supporting target object3is increased.

The lower portion of pin12may have a tapered shape that narrows toward the lower end. This makes it possible to support target objects3in various shapes.

End effector10may be capable of generating vibration for moving pin12downward. Accordingly, since pin12that has been caught halfway and has not been completely lowered can be lowered by this vibration, more accurate tracing can be performed. Therefore, in the support stage, the transmission efficiency of the force between adjacent pins12and the transmission efficiency of the force to target object3can be improved.

In addition, the force applying part is projection14B, and projection14B may come into contact with the side surface of outer pin12A when lifted to apply an inward force. As a result, when raised, projection14B can apply an inward force to outer pin12A.

End effector10may further include movable plate15that is disposed above hole plate11, raises projection14B when ascending, and pushes down pin12protruding above hole plate11and lowers projection14B when descending. Accordingly, movable plate15ascends to support target object3and descends to push out target object3. That is, both the support and the pushing of target object3can be achieved by a simple operation such as ascending and descending of movable plate15.

End effector10may further include actuator16that raises and lowers movable plate15. Accordingly, movable plate15can be raised and lowered by controlling actuator16.

The set of end effectors may also include end effector10described above and another end effector supportable by end effector10. This makes it possible to perform work while supporting the other end effector without replacing the end effector.

Furthermore, control system130that controls end effector30may include a controller (processor101), and the controller may acquire a 3D sensor image obtained by imaging the plurality of pins12protruding above hole plate11and determine, on the basis of the 3D sensor image, whether or not the end effector supports the target object. As a result, even in a case in which normal pin12is thin and it is difficult to attach a sensor to pin12itself, the support state of target object3can be determined, and the next processing can be automatically started by using the determination itself as a trigger as to whether or not target object3is supported.

The exemplary embodiments have been described above with reference to the accompanying drawings, but the present disclosure is not limited to the above examples. It is obvious that those skilled in the art can conceive various changes, modifications, substitutions, additions, deletions, and equivalents within the scope described in the claims, and it is understood that these also belong to the technical scope of the present disclosure. In addition, the components in the above-mentioned exemplary embodiments may be arbitrarily combined without departing from the spirit of the present invention.

The end effector according to the present disclosure is applicable to an apparatus for supporting an object.