JP2009190111A - Gripping device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gripping device and method for setting the size of a gripping opening correctly and performing stable gripping operation. <P>SOLUTION: This gripping device is provided with: a gripping mechanism controlling part 117 for feeding operation control values to a gripping unit to control operation of the gripping unit; an image processing part 112 for computing the size of the gripping opening formed by a gripping member; a calibration data generating part 113 for generating the calibration data indicating the relationship of the size of the gripping opening to operation control values based on the size of the gripping opening computed in the image processing part 112 for a plurality of operation control values; a data storing part 116 for storing the calibration data; and a device controlling part 115 for generating operation control value data for the gripping unit based on the calibration data stored in the data storing part 116 and feeding the operation control value data into the gripping mechanism controlling part 117. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gripping apparatus and method.

2. Description of the Related Art Conventionally, a gripping device that grips a component has been used to place or move the component at a predetermined position in an assembly process or an inspection process of various industrial products. As a gripping mechanism used in such a gripping device, an actuator using fluid, electromagnetic force, or the like is used as a drive source, and a gripping mechanism that grips a component by moving an opposing gripping member forward or backward, or is disposed around the gripping member. A chuck mechanism is known that grips a component by causing the gripping member to advance and retract radially.
For example, Patent Document 1 discloses, as such a gripping device, a microcomponent gripping device that picks up microcomponents with a chuck, a chuck opening / closing means that opens and closes a pair of claw members of the chuck by a positioning motor, and a CCD camera. Computation processing for setting the opening / closing strokes of a pair of claw members of a chuck based on a detection signal of a minute part detection means comprising the above and a detection signal of a width of a gripped portion of the minute part from the detection means and an interval between adjacent minute parts There is described a device that includes a means for controlling the rotation amount of the positioning motor by a signal from the arithmetic processing means.
In this microcomponent gripping device, the chucks facing each other are urged in the opening direction by a spring. An elevating member that can be moved in a vertical direction perpendicular to the facing direction of the chuck by a cam is provided, and a horizontal driving component force is generated by a tapered portion on the lower end side of the elevating member. As a result, the facing distance of the chuck guided in the horizontal direction by the linear guide changes in accordance with the lift position of the lift member.
JP 2004-82239 A

However, the conventional gripping device as described above has the following problems.
In the technique described in Patent Document 1, the gripping mechanism is composed of a combination of a plurality of parts, the vertical driving force generated by the rotation of the cam is transmitted to the lifting member, and the horizontal component force is lifted and lowered via the tapered portion. By transmitting from the member to the chuck, the facing distance of the chuck changes.
For this reason, the opposing distance between the chucks at a certain cam position varies due to multiple combinations of manufacturing errors and elastic deformation of each member. As a result, the size of the grip opening (grip width) varies. If the gripping opening is too wide, the object to be gripped cannot be gripped, and if the gripping opening is too narrow, the gripping force on the object to be gripped becomes too large. Such variation becomes more noticeable as the object to be grasped becomes smaller, and there is a problem that good grasping cannot be performed.
In addition, in such a gripping mechanism for minute parts, a low-rigidity tweezers must be employed as a gripping member so that the gripping force applied to the object to be gripped can be reduced or gripped in a narrow space. It may not be possible. When the tweezers are pressed to close the tweezers, the tweezers themselves are deformed. Therefore, the displacement of the pressed position and the displacement of the tweezers tip that holds the object to be grasped may not necessarily have a proportional relationship. In such a case, there is a problem that it is difficult to obtain the relationship between the gripping opening (grip width) at the tip of the tweezers and the displacement of the pressing portion by calculation.

  The present invention has been made in view of the above problems, and provides a gripping apparatus and method that can accurately set the size of the gripping opening and can perform a stable gripping operation. Objective.

In order to solve the above-described problem, in the invention according to claim 1, a gripping mechanism that grips the object to be gripped by a plurality of gripping members having at least one gripping member that can be moved forward and backward with respect to the object to be gripped. A gripping device for gripping the object to be gripped by opening / closing and moving the gripping mechanism based on the shape information and position information of the object to be gripped, and an operation control value for the gripping mechanism. A gripping mechanism control unit that sends out and controls the operation of the gripping mechanism, and detects advancing / retreating position of the gripping member that can be moved forward and backward, and calculates a size of a gripping opening formed by the plurality of gripping members A gripping opening detection unit; and a calibration data generation unit that generates calibration data representing a relationship between an operation control value of the gripping mechanism and the size of the gripping opening from the size of the gripping opening calculated by the gripping opening detection unit; A calibration data storage unit that stores the calibration data generated by the calibration data generation unit, and a target value of the size of the grip opening for gripping the object to be gripped based on the shape information of the object to be gripped. Determining and generating operation control value data for the gripping mechanism for changing the size of the gripping opening until the target value is reached based on the calibration data stored in the calibration data storage unit; It is set as the structure provided with the holding | grip movement control part sent out to a control part.
According to the present invention, an operation control value is set in the gripping mechanism control unit, and the gripping mechanism is operated by advancing and retreating the gripping member that can be advanced and retracted among the plurality of gripping members. Is detected by the gripper opening detector, and the calibration data generator generates calibration data representing the relationship between the gripper opening size and the motion control value in the gripping mechanism, and stores the calibration data in the calibration data storage unit. be able to.
Then, the gripping operation control unit determines a target value of the size of the gripping opening for gripping the target object based on the shape information of the target object, and determines the size of the gripping opening until the target value is reached. Operation control value data for the gripping mechanism for changing can be generated based on the calibration data stored in the calibration data storage unit and sent to the gripping mechanism control unit.
The gripping mechanism control unit drives the gripping mechanism so that the size of the gripping opening that matches the target value can be obtained by controlling the gripping mechanism based on the motion control value data sent from the gripping motion control unit. can do.

According to a second aspect of the present invention, in the gripping device according to the first aspect, at least one of the plurality of gripping members detects that the plurality of gripping members grips the object to be gripped, and detects a signal. It is set as the structure provided with the holding | grip detection part which generate | occur | produces.
According to this invention, since at least one of the plurality of gripping members includes the grip detection unit that detects that the plurality of gripping members grip the object to be gripped, the size of the gripping opening determined by the gripping operation control unit Is set to a target value that is narrower than the size of the gripping opening necessary for gripping, and the gripping mechanism is stopped based on a detection signal generated by the gripping detection unit. Even if there is a deviation from the calibration data, the object to be grasped can be reliably grasped.

According to a third aspect of the present invention, in the gripping device according to the first or second aspect, the gripping member that can be advanced and retracted comprises an arm-shaped member that is provided so as to be rotatable around a fixed fulcrum.
The gripping mechanism grips the object to be gripped by applying a driving force to a portion separated from the fulcrum with respect to the gripping member that can be moved forward and backward, and rotating about the fulcrum. The configuration.
According to the present invention, with respect to the arm-shaped member provided to be pivotable about the fulcrum, a driving force is applied to a portion separated from the fulcrum, and the arm-shaped member is rotated about the fulcrum of the arm-shaped member to advance and retract. The object to be grasped can be grasped by advancing and retreating the grasping member made possible, thereby changing the size of the grasping opening.

According to a fourth aspect of the present invention, in the gripping device according to the first aspect, each of the plurality of gripping members is a gripping member that can be moved forward and backward with respect to the object to be gripped.
According to the present invention, since a plurality of gripping members can all advance and retreat with respect to the object to be gripped, when gripping with the position of the object to be gripped being fixed, each gripping member is attached to the object to be gripped. The gripping can be performed from the separated state, and even when the gripping is released, each gripping member can be released from the state of being separated from the object to be gripped, so that a smoother gripping operation can be performed.

According to a fifth aspect of the present invention, in the gripping device according to the fourth aspect, each of the plurality of gripping members includes a gripping detection unit that detects that the gripped object is gripped and generates a detection signal. And
According to this invention, each of the plurality of gripping members includes a gripping detection unit that detects that the object to be gripped is gripped. Therefore, the target value of the size of the gripping opening determined by the gripping operation control unit is necessary for gripping. By setting the target value narrower than the size of the gripping opening and stopping the gripping mechanism based on the detection signal generated by each gripping detection unit, the operation of the gripping mechanism temporarily deviates from the calibration data. However, the object to be grasped can be securely grasped.

According to a sixth aspect of the present invention, in the gripping device according to the fourth or fifth aspect, each of the gripping members is an arm-like member provided to be rotatable around a fixed fulcrum, and the gripping mechanism. Is configured to grip the object to be gripped by applying a driving force to a portion of the gripping member that is spaced from the fulcrum and rotating it around the fulcrum.
According to this invention, with respect to the arm-shaped member provided so as to be rotatable about the fulcrum, the driving force is applied to the part separated from the fulcrum, and the arm-shaped member is rotated about the fulcrum of the arm-shaped member. The object to be grasped can be grasped by moving the grasping member back and forth, thereby changing the size of the grasping opening.

According to a seventh aspect of the present invention, in the gripping device according to any one of the first to sixth aspects, the gripping opening detection unit is captured by an imaging unit that captures an image of the gripping opening and the imaging unit. And an image processing unit that calculates the size of the gripping opening by performing image processing on the image of the gripping opening.
According to the present invention, the size of the gripping opening can be calculated by capturing an image of the gripping opening by the imaging unit and performing image processing on the image by the image processing unit. Accordingly, even when the gripping member is deformed, the size of the gripping opening can be accurately calculated, so that versatility can be improved.

In the invention according to claim 8, a gripping mechanism that grips the object to be gripped by a plurality of gripping members having at least one gripping member that can be moved forward and backward with respect to the object to be gripped, and an operation with respect to the gripping mechanism A gripping mechanism control unit that sends out a control value to control the operation of the gripping mechanism, and detects advancing and retreating positions of the gripping members that can be moved forward and backward to determine the size of the gripping openings formed by the plurality of gripping members. A gripping method using a gripping device including a gripping opening detection unit to calculate,
The gripping mechanism control unit is set with a plurality of motion control values of the gripping member that can be advanced and retracted to operate the gripping mechanism, and the size of the gripping opening in each of the motion control values is set to the gripping opening. Calibration data generation step for generating calibration data calculated by the detection unit and representing the relationship between the motion control value of the gripping mechanism and the size of the gripping opening, and calibration for storing the calibration data generated in the calibration data generation step A data storage step, and after performing the calibration data generation step and the calibration data storage step, based on the shape information of the object to be grasped, the size of the grip opening for grasping the object to be grasped A target value is determined, operation control value data for the gripping mechanism for changing the size of the gripping opening until reaching the target value is generated and sent to the gripping mechanism control unit. By, a method of performing a gripping step of gripping the object to be grasped.
According to the present invention, since the gripping method using the gripping device according to the first aspect is adopted, the same operation as the invention according to the first aspect is provided.

In a ninth aspect of the invention, a gripping mechanism that grips the object to be gripped by a plurality of gripping members having at least one gripping member that can be moved forward and backward with respect to the object to be gripped, and an operation with respect to the gripping mechanism A gripping mechanism control unit that sends out a control value to control the operation of the gripping mechanism, and detects advancing and retreating positions of the gripping members that can be moved forward and backward to determine the size of the gripping openings formed by the plurality of gripping members. A gripping method using a gripping device, comprising: a gripping opening detection unit to calculate; and a gripping detection unit that detects that the plurality of gripping members grip the object to be gripped and generates a detection signal, A plurality of motion control values of the gripping member that can be moved forward and backward are set in a mechanism control unit to operate the gripping mechanism, and the size of the gripping opening in each of the motion control values is determined by the gripping aperture detection unit. By A calibration data generating step for generating calibration data representing the relationship between the motion control value in the gripping mechanism and the size of the gripping opening, and a calibration data storing step for storing the calibration data generated in the calibration data generating step. And determining a target value of the size of the grip opening for gripping the object to be gripped based on the shape information of the object to be gripped after performing the calibration data generation step and the calibration data storage step. Then, operation control value data for the gripping member that is allowed to advance and retreat of the gripping mechanism for changing the size of the gripping opening until reaching the target value is generated and sent to the gripping mechanism control unit. Monitoring the generation of the detection signal by the grip detection unit, and stopping the advancement / retraction of the grip member that is enabled to advance / retreat of the grip mechanism after the detection signal is generated. , The method of performing a gripping step of gripping the object to be grasped.
According to the present invention, since the gripping method using the gripping device according to the second aspect is adopted, the same function as the invention according to the second aspect is provided.

  According to the gripping apparatus and method of the present invention, the calibration data generating unit generates calibration data representing the relationship of the size of the gripping opening to the operation control value for opening and closing the gripping mechanism, and stores the calibration data in the calibration data storage unit. Since the gripping motion controller can control the motion of the gripping mechanism based on this calibration data, the size of the gripping opening can be set accurately, and a stable gripping motion can be performed. There is an effect.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A gripping device according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic perspective view showing a schematic configuration of a gripping device according to a first embodiment of the present invention. FIG. 2A is a schematic front view of the gripping mechanism of the gripping device according to the first embodiment of the present invention. FIG.2 (b) is AA sectional drawing in Fig.2 (a). FIG. 3 is a functional block diagram showing a functional configuration of the control unit of the gripping device according to the first embodiment of the present invention. FIG. 4 is a schematic graph showing an example of calibration data of the gripping device according to the first embodiment of the present invention. The horizontal axis indicates the motion control value x, and the vertical axis indicates the size y of the grip opening.
Note that the XYZ coordinate system in the drawing is described in a common direction in each drawing for the convenience of direction reference (the same applies to the following drawings). The direction of each axis is arranged such that the XY plane coincides with the horizontal plane, and the positive Z-axis direction represents the vertically upward direction.

As shown in FIG. 1, the gripping device 100 according to the present embodiment grips a workpiece 8 (object to be gripped) made of, for example, an assembly part or a small assembly, which is arranged on a pallet 7, and the workpiece 8 in advance. It is a device that moves to the movement position set for each. The movement position may be another position on the pallet 7, for example, an assembly apparatus, an observation apparatus, a conveyance apparatus, an inspection apparatus (all not shown) such as an assembly apparatus arranged in the vicinity of the gripping apparatus 100. It may be a moving position. Alternatively, the work 8 may be temporarily moved from the pallet 7 and then returned to the original position on the pallet 7 after being observed or assembled.
1 is a schematic diagram, the work 8 is drawn in a rectangular parallelepiped shape, but this is only an example, and the work 8 can adopt an appropriate shape and has a different shape on the pallet 7. May be mixed.
In the following, at least the gripping device 100 starts the gripping operation for the shape information of the workpiece 8, in particular, the shape information related to the shape and position of the gripped portion necessary for gripping the workpiece 8, and the position information on the pallet 7. Before, it demonstrates as what is supplied to the holding | gripping apparatus 100. FIG.
For example, a unique identification number is assigned to the pallet 7 or the workpiece 8, and the identification number and the shape information and position information of each workpiece 8 are stored in a database accessible by the gripping device 100. Can be mentioned. Alternatively, the gripping device 100 includes a camera that acquires the shape information and position information of the work 8, and previously captures the pallet 7 and images of each work 8 on the pallet 7 to obtain the shape information and position information of the work 8. You may make it acquire.

  The schematic configuration of the gripping device 100 includes an X-axis stage 6, a portal column 1, a Y-axis robot 2, a Z-axis robot 3, a gripping unit 4 (gripping mechanism), and an imaging unit 5. Moreover, although illustration is abbreviate | omitted in FIG. 1, all of these are electrically connected with respect to the control unit 110 (refer FIG. 3).

The X-axis stage 6 is a moving mechanism for placing the pallet 7 and driving it along the X-axis direction, which is a uniaxial direction in a horizontal plane.
The gate-type support column 1 is a support column erected on both sides orthogonal to the drive direction of the X-axis stage 6 and a direction orthogonal to the drive direction of the X-axis stage 6 (the Y axis shown in the figure) at the upper end of the support column. This is a U-shaped support member which is formed of a beam member laid so as to straddle the X-axis stage 6 in the direction) and opens downward (Z-axis negative direction side in the drawing) when viewed in the X-axis direction.
A Y-axis robot 2 and a Z-axis robot 3 are sequentially disposed on the X-axis positive direction side of the beam member of the portal column 1.
The Y-axis robot 2 is a moving mechanism provided so as to be able to move in the Y-axis direction with respect to the beam member of the portal column 1.
The Z-axis robot 3 is a moving mechanism provided so as to be movable in the Z-axis direction with respect to the Y-axis robot 2. A gripping unit 4 is fixed to the lower end portion of the Z-axis robot 3.
With such a configuration, the gripping unit 4 is held so as to be relatively movable in the three-axis direction with respect to the pallet 7 on the X-axis stage 6.

  The gripping unit 4 constitutes a gripping mechanism that grips the work 8 with a plurality of gripping members that can be moved back and forth along the Y-axis direction in the figure with respect to the work 8. ), A base 10, a motor 11, a cam 12, gripping members 20A, 20B, and a spring 16 are provided.

The base 10 is a plate-like or block-like member fixed to the front side of the lower end portion of the Z-axis robot 3, and serves as a base for the gripping unit 4.
The motor 11 is a rotary motor that supplies a driving force for gripping the workpiece 8 by the gripping members 20A and 20B of the gripping unit 4, and is an output shaft of the motor 11 with respect to a hole drilled in the base 10. A certain motor shaft 11a is fixed in a state of projecting to the X axis positive direction side along the X axis direction in the drawing. The motor body of the motor 11 passes through the lower end portion of the Z-axis robot 3.
In this embodiment, the motor 11 employs a stepping motor, and the rotation direction and the rotation angle of the motor shaft 11a can be changed by changing the operation control value x for changing the step angle.
The cam 12 is a plate cam attached to the tip of the motor shaft 11a, and includes a cam outer peripheral surface 12a in which the radial length from the shaft center of the motor shaft 11a is changed based on a predetermined cam curve.
In this embodiment, in order to move the gripping members 20A and 20B symmetrically with respect to a plane S (see FIG. 2A) parallel to the illustrated ZX plane passing through the axial center of the motor shaft 11a, The shape of 12a is made of a convex curved surface having the same length in the radial direction on a straight line passing through the shaft center of the motor shaft 11a.

The gripping members 20A and 20B are arm-shaped members that are paired to grip and hold the workpiece 8 from the Y-axis direction in the figure. The paired surfaces are formed in a plane-symmetric shape with respect to the plane S. They are arranged to be plane symmetric.
The gripping member 20A (20B) includes a rod-shaped link 13A (13B) provided such that a cam pressing surface 13a, which is a side surface on the upper end side, can come into contact with the cam outer peripheral surface 12a of the cam 12, and the link 13A (13B) The gripping claw 15A (15B) is fixed to the lower end side of the side surface provided with the cam pressing surface 13a via a screw 17.

The gripping claws 15A (15B) of the present embodiment are made of a flexible metal or synthetic resin flat plate member. The portion of the gripping claw 15A (15B) that protrudes from the lower end of the link 13A (13B) to the Z-axis negative direction side is formed in a tapered shape in the protruding direction, and the claw tip 15a (15a) The workpiece 8 can be elastically gripped by elastic deformation at the time of contact.
The spacing between the two claw tip portions 15a facing each other is set so as to narrow from the positive direction of the Z axis toward the negative direction when viewed from the X axis direction at least immediately before the workpiece 8 is gripped. Yes.
The gripping member 20A (20B) is rotatably supported from the base 10 by a pivot 14A (14B) made of a pin member erected in the X-axis direction in the figure at an intermediate portion of the link 13A (13B). Yes. For this reason, the gripping member 20A (20B) can be rotated on the base 10 in a plane parallel to the ZY plane.

The spring 16 is a compression coil spring for biasing the lower end sides of the gripping members 20A and 20B so as to push open in the horizontal direction. Both ends of the spring 16 are fixed to the links 13A and 13B at positions closer to the grip claws 15A and 15B than the pivots 14A and 14B, and are held in a compressed state by the links 13A and 13B.
Since the holding members 20A and 20b constitute a lever having pivots 14A and 14B as fulcrums, the biasing force of the spring 16 is applied to the cam outer peripheral surface 12a of the cam 12 through the cam pressing surfaces 13a of the links 13A and 13B. Works.
The spring constant of the spring 16 is set so that an urging force that allows the cam outer peripheral surface 12a and the two cam pressing surfaces 13a to always contact each other is obtained.

With such a configuration, in the gripping unit 4, the gripping members 20 </ b> A and 20 </ b> B rotate around the pivots 14 </ b> A and 14 </ b> B in accordance with the rotation of the cam 12, respectively. Is moved forward and backward in the Y-axis direction so that the facing interval changes. By changing the facing interval from a wider state to a narrower state than the width of the gripped portion of the workpiece 8, the workpiece 8 can be held and gripped in the Y-axis direction.
In the present embodiment, at least immediately before the workpiece 8 is gripped, the facing distance between the gripping claws 15A and 15B is the ridgelines P and Q at the tips of the facing surfaces of the gripping claws 15A and 15B (points P in FIG. 2A). , Q), the workpiece 8 first comes into contact with the gripping claws 15A, 15B at the ridgelines P, Q. Therefore, the facing distance between the ridge lines P and Q is referred to as the size of the gripping opening of the gripping unit 4 or the gripping width.

The imaging unit 5 includes an imaging device made of, for example, a CCD or a CMOS device, images the gripping claws 15A and 15B from the X-axis direction, and detects an advance / retreat position in the Y-axis direction of the gripping claws 15A and 15B. Is sent to the control unit 110.
In the present embodiment, the imaging unit 5 is fixed to a support member (not shown) provided on the portal column 1 and is positioned below the beam member of the portal column 1 and above the X axis stage 6 at the X axis. It arrange | positions so that the holding | grip unit 4 can be imaged from the negative direction side. However, the imaging unit 5 may be configured to be held movably by an appropriate moving mechanism and to move to the predetermined position only when calibration data described later is created.

Next, the control unit 110 will be described.
As shown in FIG. 3, the control unit 110 includes an apparatus control unit 115 (gripping operation control unit), a movement mechanism control unit 114, a gripping mechanism control unit 117, an image acquisition unit 111, an image processing unit 112, and a calibration data generation unit 113. And a data storage unit 116.

The device control unit 115 performs overall control for operating the gripping device 100, and includes a gripping mechanism control unit 117, a movement mechanism control unit 114, an image acquisition unit 111, a calibration data generation unit 113, and a data storage unit 116. They are electrically connected so that they can send control signals and exchange data. In addition, a display unit 118 including a monitor for displaying characters and image data and an operation unit 119 including an appropriate input unit such as a keyboard and a mouse are used for the operator of the grasping apparatus 100 to perform an operation input. Electrically connected.
The apparatus control unit 115 receives the shape information of the work 8 and the position information of the work 8 on the pallet 7 from the communication line (not shown) or the operation unit 119 until the pallet 7 is placed on the X-axis stage 6. In addition, information on the procedure for gripping and moving the workpiece 8 is supplied. Information about the procedure includes, for example, information such as the movement position, the number of movements, and the movement order of the workpiece 8.

  The movement mechanism control unit 114 controls the movement positions of the movement mechanisms of the X-axis stage 6, the Y-axis robot 2, and the Z-axis robot 3 based on a control signal from the apparatus control unit 115, and This is for moving the position.

  The gripping mechanism control unit 117 moves the gripping claws 15A and 15B of the gripping unit 4 forward and backward in the Y-axis direction based on the operation control value x sent from the device control unit 115. In the present embodiment, the operation control value x controls the amount of rotation of the motor 11 from the reference position.

  The image acquisition unit 111 acquires an image signal transmitted from the imaging unit 5 based on a control signal from the apparatus control unit 115, performs noise removal, brightness correction, and the like as necessary, and performs an image of the frame image. Data is generated and sent to the image processing unit 112.

The image processing unit 112 performs appropriate image processing, such as edge extraction and pattern matching, on the image data acquired by the image acquisition unit 111, for example, thereby increasing the size of the grip opening formed by the grip claws 15A and 15B. Then, y (opposite distance of PQ) is calculated, and the calculation result is sent to the calibration data generation unit 113.
The image processing unit 112, together with the imaging unit 5 and the image acquisition unit 111, detects the advance / retreat position of the grip members 20 </ b> A and 20 </ b> B in the Y-axis direction, and calculates the size of the grip opening formed by the grip members 20 </ b> A and 20 </ b> B. A grip opening detection unit is configured.

The calibration data generation unit 113 acquires the size y of the gripping opening from the image processing unit 112 and calculates the size y of the gripping opening from the device control unit 115 based on the control signal of the device control unit 115. The motion control value x when the image is acquired is acquired, and calibration data representing the relationship between the gripping opening size y with respect to the motion control value x is generated from a plurality of data (x, y). . The calibration data may be generated as a set of coefficients of a curve obtained by fitting a curve from a plurality of (x, y), or may be generated as table data.
The data storage unit 116 stores the calibration data generated by the calibration data generation unit 113.

FIG. 4 is a schematic graph showing an example of calibration data.
In this example, as shown by a curve 200 in FIG. 4, the size y of the gripping opening monotonously increases as the operation control value x increases, and more specifically, a small region and a large region of the operation control value x. Then, the size y of the grip opening increases at a relatively small change rate, and in the intermediate region between them, a non-linear change in which the size y of the grip opening increases at a relatively large change rate is shown. Yes.

  As the device configuration of the control unit 110, the functions of the above-described units may be realized by dedicated hardware. A control program for realizing the function is executed.

Next, the operation of the gripping device 100 will be described.
5A and 5B are schematic front views showing the open state and the closed state of the gripping mechanism of the gripping device according to the first embodiment of the present invention, respectively. FIG. 6 is a schematic diagram illustrating an example of an image captured in the calibration data generation step of the gripping method according to the first embodiment of the present invention. FIG. 7 is a flowchart illustrating a calibration data generation process and a calibration data storage process in the gripping method according to the first embodiment of the present invention. FIG. 8 is a flowchart illustrating a gripping process in the gripping method according to the first embodiment of the present invention.

In the gripping unit 4, the size of the gripping opening is changed by rotating the motor shaft 11a by the motor 11 and changing the forward and backward positions of the gripping claws 15A and 15B in the Y-axis direction.
For example, FIG. 5A shows that the distance D between the contact points between the cam outer peripheral surface 12a of the cam 12 and the cam pressing surfaces 13a of the links 13A and 13B is the minimum value D _min due to the rotation of the motor 11, and the size of the gripping opening. A state when PQ (opposite distance of PQ) becomes d _max is shown. At this time, the holding members 20A and 20B receive the urging force of the spring 16, and the pivots 14A and 14b serve as leverage points to apply a pressing force from the cam pressing surfaces 13a to the cam outer peripheral surface 12a. A contact state is maintained between the two.
5B, when the motor 11 further rotates about 90 degrees from the state of FIG. 5A, the distance D between the contact points of the cam outer peripheral surface 12a and each cam pressing surface 13a is the maximum value. The state when D _max (however, D _max > D _min ) is shown.
As the inter-contact distance D of each cam pressing surface 13a is changed to _Dmax , the gripping members 20A and 20B are rotated counterclockwise and clockwise around the pivots 14A and 14B, respectively, in the drawing sheet. Yes. For this reason, the size PQ of the grip opening changes to d _min (where d _min <d _max ).

If the gripping members 20A and 20B are rigid bodies, the distance D between the contacts of each cam pressing surface 13a and the size PQ of the gripping opening are in a proportional relationship according to the leverage ratio. Therefore, the size PQ of the gripping opening is determined only by the relationship between the cam curve of the cam outer peripheral surface 12a and the rotational position of the cam 12.
However, for example, when the size of the workpiece 8 is small, the gripping members 20A and 20B often have to be similarly reduced, and accordingly, the rigidity of the gripping members 20A and 20B must be reduced. The holding members 20 </ b> A and 20 </ b> B are bent by the urging force of 16. Since the biasing force of the spring 16 increases as the gripping opening is narrowed, the amount of deflection of the gripping members 20A and 20B also increases. As a result, the size y of the gripping opening with respect to the motion control value x becomes larger than the design value in which the gripping members 20A and 20b are rigid bodies, and the workpiece 8 may not be gripped satisfactorily.
Further, manufacturing errors and wear of the cam outer peripheral surface 12a also cause the size of the grip opening to vary.
Therefore, the gripping device 100 detects the size y of the gripping opening with respect to the motion control value x, creates calibration data, and can accurately control the size y of the gripping opening based on the calibration data. Yes.
That is, the gripping device 100 has an initialization mode for performing a calibration data generation process and a calibration data storage process, and a normal mode for performing a gripping process, so that any operation can be selected by the operation unit 119. I have to.
The gripping process is performed at least once after executing the initial mode and storing the calibration data in the data storage unit 116.
The initialization mode is preferably automatically executed when the power is turned on, or after a certain time or after a certain number of gripping operations. Further, even when it is detected that the shape of the work 8 has changed and the size of the grip opening necessary for gripping has changed, it is preferable to automatically execute it prior to the gripping step.

First, the initialization mode will be described.
In the calibration data generation step, the gripping mechanism control unit 117 sets a plurality of motion control values x to operate the gripping unit 4, calculates the gripper opening size y in each motion control value x, and the gripping unit 4 This is a step of generating calibration data representing the relationship between the motion control value x and the size y of the grip opening. The calibration data storage step is a step of storing the generated calibration data in the data storage unit 116. In the present embodiment, these steps are executed according to the flow shown in FIG.

First, in step S1, a control signal is sent from the apparatus control unit 115 to the moving mechanism control unit 114, the X-axis stage 6, the Y-axis robot 2, and the Z-axis robot 3 are driven, and the gripping unit 4 is moved to a predetermined photographing position. Move to.
Here, for example, as shown in FIG. 7, the predetermined photographing position is set in advance as a position where the opening / closing operation of each nail tip 15 a of the gripping claws 15 </ b> A and 15 </ b> B can be imaged at substantially the center of the imaging frame of the imaging unit 5. It is stored in the device control unit 115.

Next, in step S2, setting the operation control value x to the initial value _{x s.} The initial value x _s may be set to either the large side or the small side of the gripping opening. However, in this embodiment, the gripping opening is sequentially reduced to acquire the data of the gripping opening size y. The opening is set to a value that is larger than the gripped width of the workpiece 8.

  Next, in step S3, the set motion control value x is sent from the apparatus control unit 115 to the gripping mechanism control unit 117, and the motor 11 is rotated by the gripping mechanism control unit 117, so that the rotational position based on the motion control value x is reached. The cam 12 is positioned in

  Next, in step S <b> 4, the frame image of the grip unit 4 captured by the imaging unit 5 is acquired by the image acquisition unit 111. The acquired image signal is subjected to processing such as noise removal and luminance correction as necessary, and then sent to the image processing unit 112 as image data. Thereby, for example, the images of the tip portions of the grip claws 15A and 15B viewed from the negative X-axis direction as shown in FIG. 7 are acquired.

In step S5, the image processing unit 112 detects the positions of the points P and Q on the image data from the image data, obtains the distance PQ, converts it to the actual distance by the magnification of the imaging unit 5, and calculates this value. The size of the gripping opening is y. Then, the size y of the grip opening is sent to the calibration data generation unit 113.
The positions of the points P and Q on the image can be obtained, for example, by extracting the edges of the images of the gripping claws 15A and 15B and detecting them as intersections.
The calibration data generation unit 113 further acquires an operation control value x corresponding to the image for which the size y of the grip opening that has been sent is acquired from the apparatus control unit 115, and generates a data set (x, y). To do.
In step S <b> 6, the calibration data generation unit 113 stores the generated data set (x, y) in the data storage unit 116.

Next, in step S7, the operation control value x is updated to a value changed by the increment Δx. In the present embodiment, Δx is set to a negative value.
Δx may be a constant value, and the operation control value x may be changed at equal intervals, but Δx may be changed according to the value of x to be changed at unequal intervals. For example, since it is necessary to accurately control the size y of the gripping opening from a short time before gripping the workpiece 8 until the gripping of the workpiece 8 is completed, the data interval of x is narrowed between them, and otherwise In this range, the data interval of x may be coarse.

In step S8, and determines whether the operation control value x has passed the end value x _e. In the present embodiment, since x _e <x _s , it is determined whether x> x _e .
(For x ≦ _{x e)} if not x> _{x e,} the process proceeds to step S3, and repeats the above steps S 3 to S 8.
If it is x> _{x e,} the process proceeds to step S9.

In step S9 (calibration data generation step), the calibration data generation unit 113 generates a set of curve coefficients obtained by, for example, curve fitting using a plurality of generated (x, y). Calibration data is generated by generating table data obtained by interpolating these (x, y).
Next, in step S10 (calibration data storage step), the calibration data is stored in the data storage unit 116.

  If the interval between the operation control values x can be set closely, a plurality of (x, y) itself obtained by repeating steps S3 to S8 may be used as the table data and the calibration data. In this case, the calibration data generation process and the calibration data storage process are sequentially performed until the process leaves step S8, and steps S9 and S10 can be omitted.

Next, in step S11, the apparatus control unit 115 causes the gripping mechanism control unit 117 to set the motion control value x to, for example, the initial value x ₀ (the gripping operation start value determined by the size of the gripping width of the workpiece 8). However, by setting the _{x s ≧ x 0> x e} ), to drive the gripping unit 4 is initialized to the initial value _{y 0} the magnitude y of the gripping opening.
Then, the device control unit 115 sets a control signal for moving the gripping operation to the standby position for the gripping operation, and positions the gripping unit 4 from the imaging position to the standby position for the gripping operation.
By executing the above flow, a calibration data generation process and a calibration data storage process are performed.

Next, the normal mode will be described.
When the normal mode is selected by the operation unit 119, a gripping process is performed based on FIG.
First, in step S20, the apparatus control unit 115 acquires the shape information, position information, and movement procedure information of the workpiece 8. When these shape information, position information, and movement procedure information are not stored in advance, the information is obtained by accessing an appropriate database, or the display unit 118 is prompted to input from the operation unit 119.

Next, in step S < _b > 21, the apparatus control unit 115 sets a target value Yc for the size y of the gripping opening based on the shape information of the workpiece 8. Target value Y _c is gripping claws 15A, 15B are further deflection in contact with the retained portion of the work 8, the gripping claws 15A, by the elastic force of 15B, is set to a size capable of biasing the gripping force on the workpiece 8.
Next, in step S22, the apparatus control unit 115 sets a time change y (t) that is a data string of the size y of the gripping opening until the target value _Yc is reached. In this case, y (t), which may be changed to a constant with respect to time t, is changed fast when you are away from the target value Y _c, it is better to so as to slowly change in the vicinity of the target value Y _c This is preferable because the efficiency of the gripping process can be improved.

Next, in step S23, the apparatus control unit 115 refers to the calibration data in the data storage unit 116 and converts y (t) into operation control value data x (t) that is a corresponding data string.
In step S24, x = x (0) is set in the gripping mechanism control unit 117, and the gripping unit 4 is driven.
Next, in step S25, the apparatus control unit 115 sends a control signal to the moving mechanism control unit 114 based on the position information of the work 8, moves the gripping unit 4 onto the work 8, and grips 15A. , 15B are positioned at positions where the workpiece 8 is sandwiched from the Y-axis direction.
Next, in step S <b> 26, the apparatus control unit 115 sequentially sends the operation control data x (t) to the gripping mechanism control unit 117 to drive the gripping unit 4. Thereby, the gripping opening of the gripping unit 4 is changed according to y (t), and finally the target value _Yc is reached, whereby the workpiece 8 is gripped by the gripping unit 4.

  Next, in step S <b> 27, the apparatus control unit 115 sends a control signal for setting the moving position of the gripping unit 4 to the moving mechanism control unit 114 based on the moving procedure information, and moves the position of the workpiece 8. When the movement position is reached, an operation control value x that widens the gripping opening is set in the gripping mechanism control unit 117, and the gripping of the workpiece 8 by the gripping unit 4 is released.

Next, in step S28, it is determined whether there is another workpiece 8 to be gripped. If there is no other workpiece 8 to be gripped, the gripping process is terminated.
If there is another workpiece 8 to be gripped, the process proceeds to step S20, and steps S20 to S28 are repeated.
In this way, the gripping process is completed.

As described above, according to the gripping device 100 of the present embodiment, prior to the gripping process, the gripping unit 4 is operated by the calibration data generation unit including the imaging unit 5, the image acquisition unit 111, the image processing unit 112, and the calibration data generation unit 113. Calibration data (x, y) representing the relationship of the size y of the grip opening with respect to the motion control value x for opening and closing the head is generated and stored in the data storage unit 116. The operation of the gripping unit 4 can be controlled based on the calibration data by the apparatus control unit 115 which is a control unit.
For this reason, in the opening / closing operation of the gripping unit 4, even when the gripping members 20A and 20B are bent or the cam 12 has an error in the opening / closing amount due to manufacturing errors or wear, the size y of the gripping opening is set. It can be set accurately and a stable gripping operation can be performed.

Next, first and second modifications of the first embodiment will be described.
FIG. 9 is a schematic partial enlarged view showing a gripping claw of a first modified example of the gripping device according to the first embodiment of the present invention. FIG. 10 is a schematic partial enlarged view showing a gripping claw of a second modified example of the gripping device according to the first embodiment of the present invention.

As shown in FIG. 9, the first modification is an example in which marks 18 </ b> A and 18 </ b> B are provided in the vicinity of the claw tip portions 15 a of the grip claws 15 </ b> A and 15 </ b> B of the grip device 100 of the first embodiment. The marks 18 </ b> A and 18 </ b> B are both provided in a part that can be imaged by the imaging unit 5 at the imaging position.
In the example of FIG. 9, the mark 18 </ b> A (18 </ b> B) is a cross-shaped mark in which the intersection point p (q) is formed in a fixed positional relationship with respect to the point P (Q) that determines the gripping opening.

Thereby, in the calibration data generation step, the marks 18A and 18B are extracted from the image acquired by the image acquisition unit 111 by image processing, the positions of the intersection points p and q are obtained, and the intersection points p and q stored in advance are obtained. From the positional relationship between the points P and Q, the size y of the gripping opening can be obtained.
As means for extracting the marks 18A and 18B, means such as pattern matching can be suitably employed by storing the shapes of the marks 18A and 18B in advance in addition to edge extraction and the like.

The marks 18A and 18B are not limited to a cross shape as long as the position on the image can be acquired by image processing, and may be an appropriate shape such as a circle, a V-shaped mark, or a polygonal mark. . Moreover, it may be formed by printing or the like on the surfaces of the gripping claws 15A and 15B, or may be engraved or penetrated from the surface.
If such marks 18A and 18B are provided, for example, when gripping is performed at a position different from the ridgelines P and Q, a position closer to the gripping position than when the gripping opening is calculated from the points P and Q. Can detect the size of the grip opening.

The second modified example is an example in which the shape of the gripping claw is changed according to the shape of the work 8, and instead of the gripping claw 15B of the gripping device 100 of the first embodiment, as shown in FIG. A gripping claw 15C is provided.
In the example shown in FIG. 10, a V-shape is formed on the surface facing the gripping claw 15 </ b> A in the vicinity of the claw tip 15 a of the gripping claw 15 </ b> C so that the work 8 has a circular cross section such as an electric wire. A gripping groove 19 made of a groove is provided.
In this case, the workpiece 8 abuts the points T and U on the opening side of the gripping groove 19 on the gripping claw 15C side, and the point R on the side surface of the gripping claw 15A facing the gripping groove 19 on the gripping claw 15A side. Abut.

According to such a configuration, the workpiece 8 can be reliably held at a certain position in the Z-axis direction by the holding groove 19, and the holding position can be stabilized even if the workpiece 8 is moved in the holding state.
The gripping opening in this case may be converted into a distance RT or a distance RU that becomes a substantial gripping opening after detecting the positions of the points P and Q, as in the first embodiment. The points T and U are more preferably obtained directly from the acquired image.
Further, the size of the gripping opening in this case may be obtained as a diameter of a circle that passes through the points T and U and has the side surface of the gripping claw 15A where the point R is formed as a tangent.

  In this modification, the grip groove 19 is provided in the grip claw 15C. However, the grip claw 15A may be provided with a similar shape such as the grip groove 19.

Next, a third modification of the first embodiment will be described.
FIGS. 11A and 11B are a schematic front view and a right side view showing a gripping mechanism of a third modification of the gripping device according to the first embodiment of the present invention.

  A gripping device 100A according to this modification includes a gripping unit 40 (grip mechanism) and a control unit 110A instead of the gripping unit 4 and the control unit 110 of the gripping device 100 of the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment.

As shown in FIGS. 11A and 11B, the gripping unit 40 includes a base 10, tweezers 42, and a pair of actuators 43 that move the tip portions 42 a of the tweezers 42 to the closing side.
In the tweezers 42, the holding members 42A and 42B each having an arcuate arm shape are provided in plane symmetry with respect to the plane S, and the respective base end portions 42b are joined to face each other in the Y-axis direction, and are opposite to the base end portion 42b. Each of the end portions 42a on the side is provided with a tapered shape when viewed from the Y-axis direction, and is configured to face the Y-axis direction with a predetermined distance therebetween.
The tweezers 42 are fixed to the base 10 by tweezer support portions 41 provided on the base 10 at the joined base end portion 42b.
The holding members 42A and 42B are made of, for example, a flexible metal plate or a synthetic resin plate, and constitute a cantilever elastic bending beam to which the base end portion 42b is fixed.

In this embodiment, the actuator 43 employs an actuator configured such that the piezoelectric element expands and contracts by changing the applied voltage, and thereby the pressing member that contacts the tweezers 42 advances and retreats in the Y-axis direction.
One actuator 43 is disposed in the vicinity of the pressed portion 42c in the middle portion in the longitudinal direction (Z-axis direction) of the gripping members 42A and 42B, and is opposed to each other along the Y-axis direction with the tweezers 42 interposed therebetween. . Therefore, the actuator 43 can bias the gripping member 42A in the positive direction from the Y-axis negative direction and the gripping member 42B in the negative direction from the Y-axis positive direction.
Each actuator 43 is electrically connected to the gripping mechanism control unit 117A, and a voltage is applied based on the operation control value x set in the gripping mechanism control unit 117A from the device control unit 115, and the advancement / retraction amount of the pressing member is set. It is going to change.

According to the gripping apparatus 100A of the present modification, the operation control value x set in the gripping mechanism control unit 117A is different only in that the voltage value for moving the pressing member of the actuator 43 back and forth is different. As in the first embodiment, the calibration data generation process, the calibration data storage process, and the gripping process can be performed.
That is, when the pressing member of the actuator 43 advances toward the gripping members 42A and 42B according to the operation control value x, the pressing force is urged from the pressed portions 42c, respectively, and the gripping members 42A and 42B bend, By rotating with the end portion 42b as a fulcrum, the tip end portion 42a advances to the plane S side. At this time, the distance between the points P and Q of the distal end portion 42a gives the size of the gripping opening. Similarly, when the pressing member of the actuator 43 is retracted, the tip end portion 42a is retracted in the Y-axis direction, the points P and Q are separated from each other, and the size of the gripping opening is increased.
At this time, the gripping members 42A and 42B are flexible elastic bending beams, and the position of the pressed portion 42c and the position of the distal end portion 42a are not necessarily in a simple proportional relationship, but calibration data is generated. By performing the process, calibration data indicating the relationship between the operation control value x that determines the position of the pressed portion 42c and the size y of the gripping opening that is determined from the position of the distal end portion 42a is obtained. Therefore, it is possible to accurately control the size of the accurate grip opening.

[Second Embodiment]
A gripping device according to a second embodiment of the present invention will be described.
FIG. 12A is a schematic front view of the gripping mechanism of the gripping device according to the second embodiment of the present invention. FIG.12 (b) is BB sectional drawing in Fig.12 (a). FIG. 13 is a functional block diagram showing a functional configuration of a control unit of the gripping device according to the second embodiment of the present invention.

The gripping device 100B of the present embodiment includes a gripping unit 4A (gripping mechanism) and a control unit 120 (see FIG. 13) instead of the gripping unit 4 and the control unit 110 of the gripping device 100 of the first embodiment. As a result, the gripping device 100 of the first embodiment includes a gripping detection unit that detects that the gripping members 20A and 20B grip the workpiece 8 and generates a detection signal.
The grip detection unit can adopt an appropriate configuration according to the object to be gripped or the gripping mechanism. In the present embodiment, an example in which the workpiece 8 is suitable for an electric conductor will be described.
Hereinafter, a description will be given centering on differences from the first embodiment.

  As shown in FIGS. 12A and 12B, the gripping unit 4A has the same member configuration as the gripping unit 4, but in the gripping unit 4A, the gripping claws 15A and 15B are made of an electric conductor. The links 13A and 13B are electrically insulated from each other and are electrically connected to the detection signal acquisition unit 121 of the control unit 120 by wires 50a and 50b, respectively. Accordingly, the grip claws 15A and 15B also serve as the grip detection units 50 and 50, respectively.

As shown in FIG. 13, the control unit 120 is obtained by adding a detection signal acquisition unit 121 to the control unit 110 of the first embodiment and electrically connecting it to the device control unit 115.
The detection signal acquisition unit 121 detects that the workpiece 8 is gripped by the gripping claws 15 </ b> A and 15 </ b> B by applying a voltage to the wires 50 a and 50 b and detecting continuity, and sends the detection signal to the device control unit 115. To do.
For example, a detection signal is generated when a current greater than or equal to a threshold value is generated and conduction between the wirings 50a and 50b is detected.
This threshold value is set to a value that can detect the state in which the gripping claws 15A and 15B are in contact with the workpiece 8 in consideration of the contact resistance between the gripping claws 15A and 15B and the workpiece 8. Further, when the gripping claws 15A and 15B are deformed from the start of gripping, the contact area with the workpiece 8 changes, and when the current changes accordingly, the contact with which the gripping force on the workpiece 8 is optimal The threshold is determined in consideration of the size of the area. The threshold value does not necessarily have to match the value at which the gripping force with respect to the workpiece 8 is optimal. For example, when a detection signal is generated, an operation control value for further narrowing the gripping opening so as to optimize the gripping force is sent from the device control unit 115 to the gripping mechanism control unit 117, and the operation based on the operation control value is completed. Sometimes an optimum gripping force may be obtained.

According to such a gripping device 100B, the initialization mode is executed according to the flow shown in FIG. 6 and the calibration data is stored in the data storage unit 116 in the same manner as the gripping device 100 of the first embodiment. .
In the normal mode, the gripping process is performed according to the flow shown in FIG. 8, but the following points are changed and executed.
First, in step S22, advance to generate a y (t) until slightly reduced gripping opening than the target value _{Y c,} in step S23, converts this y (t) all x (t).
In step S26, as in the first embodiment, the apparatus control unit 115 sequentially sends the operation control value data x (t) to the gripping mechanism control unit 117 and drives the gripping unit 4. At the same time, The device control unit 115 monitors the presence / absence of a detection signal from the detection signal acquisition unit 121. Then, after the detection signal is generated, the driving of the gripping unit 4 is stopped. That is, in response to the generation of the detection signal, the transmission of the operation control value data x (t) from the device control unit 115 to the gripping mechanism control unit 117 is stopped, or in response to the generation of the detection signal, for example, the gripping force Then, an operation control value for further narrowing the gripping opening is sent out so as to optimize the operation, and an operation based on this operation control value is performed and then stopped. Then, the gripping position at the time of stopping is held, and the process proceeds to step S27.
On the other hand, when the gripping opening detection signal be driven to x (t) which would reach the target value Y _c does not occur, continue to drive in x (t) which corresponds to a narrower gripping opening. If no detection signal is generated even when the final value of x (t) generated in step S22 of the present embodiment is reached, an error message is displayed on the display unit 118, and the driving of the gripping unit 4 is stopped.

  As described above, according to the gripping device 100B, the gripping detection unit 50 is provided, so that the state of gripping the workpiece 8 can be detected. Therefore, even when the size of the gripping opening of the gripping unit 4 deviates from the relationship of the calibration data with respect to the operation control value x for some reason, it is possible to prevent the gripping failure of the workpiece 8 from occurring. .

Next, a modification of this embodiment will be described.
FIG. 14 is a schematic front view and a right side view showing a gripping mechanism according to a modification of the second embodiment of the present invention.

A gripping device 100C of this modification includes a gripping unit 40A (grip mechanism) and a control unit 120A instead of the gripping unit 4A and the control unit 120 of the gripping device 100B of the second embodiment.
Here, the gripping unit 40A is obtained by adding a gripping detection unit 51 to the gripping unit 40 of the third modified example of the first embodiment. The control unit 120A includes a gripping mechanism control unit 117A according to the third modification of the first embodiment, instead of the gripping mechanism control unit 117 of the control unit 120, and a detection signal acquisition unit of the control unit 120. Instead of 121, a detection signal acquisition unit 121A is provided.
The following description will focus on differences from the second embodiment and the third modification of the first embodiment.

The grip detection unit 51 of the present modification grips the workpiece 8 by utilizing the fact that the tip portion 42a of the gripping members 42A and 42B grips the workpiece 8 so that distortion or stress is generated in the tip portion 42a. This is a sensor that detects this, and is fixed to each tip 42a of the gripping members 42A and 42B.
As a specific configuration of the grip detection unit 51, for example, a strain gauge, a piezoelectric sensor, or the like can be employed. The output terminal of each gripping detection unit 51 is electrically connected to the detection signal acquisition unit 121A by wirings 50a and 50b.
The detection signal acquisition unit 121A extracts changes in strain and stress detected by the grip detection unit 51 as an electrical signal, and when the electrical signal exceeds a threshold value corresponding to deformation due to the grip state of the grip members 42A and 42B, A detection signal is generated for the device control unit 115. The method for determining the threshold value may be the same as in the second embodiment.

According to such a gripping device 100 </ b> C, it is possible to detect the state of gripping the workpiece 8 by providing the grip detection unit 51. For this reason, even when the size of the gripping opening of the gripping unit 40A deviates from the relationship of the calibration data with respect to the operation control value x for some reason, it is possible to prevent the gripping failure of the workpiece 8 from occurring. .
In the present modification, the grip detection unit 51 does not need to energize the work 8, so that even when the work 8 is an insulator or it is not preferable to pass a current, the grip state is accurately determined. Can be detected.

  In the above description, the gripping member is described as an example in the case of an arm-shaped member that is provided so as to be rotatable around a fixed fulcrum that is easily deformed by an urging force that performs an opening / closing operation. The gripping member may be an arm-shaped member that moves in parallel with each other and grips an object to be gripped. In addition, the shape is not limited to the arm-shaped member as long as the object to be grasped can be gripped, and may be a member such as a plate shape, a bowl shape, a block shape, or a rod shape.

In the above description, the grip opening detection unit is described as an example of a configuration including an imaging unit and an image processing unit. However, if the size of the grip opening can be detected, a configuration using other detection means is used. It may be a gripping opening detector.
Examples of the configuration of the other gripping opening detection unit include a laser length measuring device that can measure the distance between the separated members.

  Further, in the above description, the example in which the gripping mechanism is held so as to be movable in the three-axis directions has been described. For example, the gripping unit 4 is rotated with a degree of freedom of rotation with respect to the Z-axis robot 3. You may hold | maintain the holding | grip unit 4 rotatably by attaching via a robot.

  Further, in the above description, the example in which the gripping mechanism opens and closes on both sides with respect to the object to be gripped has been described. It may be a one-side driven gripping mechanism.

In the above description, the gripping member of the gripping mechanism is described as an example in which the gripping opening is changed by facing the uniaxial direction and moving back and forth along the uniaxial direction. However, there may be provided a multi-jaw chuck mechanism in which three or more are provided and each advance and retract radially with respect to the center of the object to be grasped. In this case, the size of the gripping opening can be replaced with the inscribed circle diameter with which the tip of each gripping member abuts, the distance between the gripping members facing each other, or the like.
In such a configuration, the imaging position of the imaging unit is not limited to the side of the gripping mechanism, but is set to an appropriate position at which a change in the gripping opening is easily captured, for example, below the gripping mechanism.

In the above description, when the grip detection unit is provided, the example in which the grip detection unit is provided on all of the plurality of grip members has been described. However, by providing the grip detection unit on any of the plurality of grip members, In the case where it is possible to detect that an object has been gripped, a configuration in which grip detection units fewer than the number of grip members is provided may be employed.
In addition, the gripping member provided with the gripping detection unit may be a gripping member that can be moved forward and backward with respect to the object to be gripped, or may be a gripping member that is not enabled to advance and retract.

  In addition, all the constituent elements described in the above embodiments and modifications can be implemented in appropriate combination within the scope of the technical idea of the present invention.

It is a typical perspective view showing a schematic structure of a grasping device concerning a 1st embodiment of the present invention. It is the typical front view of the holding | grip mechanism of the holding | grip apparatus which concerns on the 1st Embodiment of this invention, and its AA sectional drawing. It is a functional block diagram which shows the function structure of the control unit of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a typical graph which shows an example of the calibration data of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a typical front view which shows the open state and closed state of the holding | grip mechanism of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram of an example of the image imaged at the calibration data generation process of the holding | grip method which concerns on the 1st Embodiment of this invention. It is a flowchart explaining the flowchart of the calibration data generation process in the holding | grip method which concerns on the 1st Embodiment of this invention, and a calibration data storage process. It is a flowchart explaining the holding | grip process in the holding | grip method which concerns on the 1st Embodiment of this invention. It is a typical fragmentary enlarged view which shows the holding nail | claw of the 1st modification of the holding | grip apparatus which concerns on the 1st Embodiment of this invention. It is a typical fragmentary enlarged view showing a gripping claw of the 2nd modification of a gripping device concerning a 1st embodiment of the present invention. It is the typical front view which shows the holding | grip mechanism of the 3rd modification of the holding | grip apparatus which concerns on the 1st Embodiment of this invention, and its right view. It is the typical front view of the holding mechanism of the holding apparatus which concerns on the 2nd Embodiment of this invention, and its BB sectional drawing. It is a functional block diagram which shows the function structure of the control unit of the holding | gripping apparatus which concerns on the 2nd Embodiment of this invention. It is the typical front view which shows the holding | grip mechanism of the modification of the holding | grip apparatus which concerns on the 2nd Embodiment of this invention, and its right view.

Explanation of symbols

2 Y-axis robot 3 Z-axis robot 4, 4A, 40, 40A Gripping unit (gripping mechanism)
5 Imaging unit (gripping opening detection unit)
6 X-axis stage 8 Workpiece (object to be gripped)
11 Motor 12 Cam 12a Cam outer peripheral surface 13A, 13B Link 14A, 14B Pivot (fulcrum)
15A, 15B Grip 19 Grip groove 20A, 20B, 42A, 42B Grip member 42 Tweezers 42b Base end (fulcrum)
43 Actuator 50, 51 Grip detection unit 100, 100A, 100B, 100C Gripping device 110, 110A, 120, 120A Control unit 111 Image acquisition unit (gripping opening detection unit)
112 Image processing unit (gripping opening detection unit)
113 Calibration data generation unit 115 Device control unit (gripping operation control unit)
116 Data storage unit (calibration data storage unit)
117, 117A Grip mechanism control unit 121, 121A Detection signal acquisition unit x Operation control value x (t) Operation control value data y Gripping aperture size Y _c Target value (Target value of gripping aperture size)

Claims (9)

A gripping mechanism for gripping the object to be gripped by a plurality of gripping members having at least one gripping member capable of moving forward and backward with respect to the object to be gripped, and based on the shape information and position information of the object to be gripped; A gripping device for gripping the object to be gripped by opening / closing and moving a gripping mechanism,
A gripping mechanism control unit that sends an operation control value to the gripping mechanism to control the operation of the gripping mechanism;
A gripping opening detection unit that detects advancing and retreating positions of the gripping members that are capable of moving back and forth, and calculates a size of a gripping opening formed by the plurality of gripping members;
A calibration data generation unit that generates calibration data representing the relationship between the operation control value in the gripping mechanism and the size of the gripping opening from the size of the gripping opening calculated by the gripping opening detection unit;
A calibration data storage unit for storing the calibration data generated by the calibration data generation unit;
Based on the shape information of the object to be grasped, a target value of the size of the grasping opening for grasping the object to be grasped is determined, and the size of the grasping opening is changed until the target value is reached. A gripping apparatus comprising: a gripping motion control unit that generates motion control value data for the gripping mechanism based on calibration data stored in the calibration data storage unit and sends the data to the gripping mechanism control unit.   The at least one of the plurality of gripping members includes a grip detection unit that detects that the plurality of gripping members grip the object to be gripped and generates a detection signal. Gripping device. The gripping member that can be advanced and retracted is composed of an arm-shaped member that is provided so as to be rotatable around a fixed fulcrum,
The gripping mechanism grips the object to be gripped by applying a driving force to a portion separated from the fulcrum with respect to the gripping member that can be moved forward and backward, and rotating about the fulcrum. The gripping device according to claim 1 or 2, characterized in that   The gripping apparatus according to claim 1, wherein each of the plurality of gripping members is a gripping member that can advance and retreat with respect to the object to be gripped.   The gripping device according to claim 4, wherein each of the plurality of gripping members includes a gripping detection unit that detects the gripping of the object to be gripped and generates a detection signal. Each gripping member is composed of an arm-like member provided so as to be rotatable around a fixed fulcrum,
The gripping mechanism grips the object to be gripped by applying a driving force to a portion spaced from the fulcrum with respect to each gripping member and rotating it around the fulcrum. The gripping device according to claim 4 or 5. The gripping opening detector is
An image pickup unit that picks up an image of the gripping opening, and an image processing unit that calculates the size of the gripping opening by performing image processing on the image of the gripping opening picked up by the image pickup unit. The gripping device according to any one of claims 1 to 6. A gripping mechanism for gripping the object to be gripped by a plurality of gripping members having at least one gripping member capable of moving forward and backward with respect to the object to be gripped, and an operation control value to the gripping mechanism to send the gripping mechanism A gripping mechanism control unit that controls the movement of the gripping member, and a gripping opening detection unit that calculates the size of the gripping opening formed by the plurality of gripping members by detecting the advancing / retreating position of the gripping member that can be moved back and forth. A gripping method using a gripping device,
The gripping mechanism control unit is set with a plurality of motion control values of the gripping member that can be advanced and retracted to operate the gripping mechanism, and the size of the gripping opening in each of the motion control values is set to the gripping opening. A calibration data generation step for generating calibration data calculated by the detection unit and representing the relationship between the motion control value in the gripping mechanism and the size of the gripping opening;
A calibration data storage step for storing the calibration data generated in the calibration data generation step,
After performing the calibration data generation step and the calibration data storage step,
Based on the shape information of the object to be grasped, a target value of the size of the grasping opening for grasping the object to be grasped is determined,
A gripping step of gripping the object to be gripped by generating operation control value data for the gripping mechanism for changing the size of the gripping opening until the target value is reached and sending it to the gripping mechanism control unit A gripping method characterized by: A gripping mechanism for gripping the object to be gripped by a plurality of gripping members having at least one gripping member capable of moving forward and backward with respect to the object to be gripped, and an operation control value to the gripping mechanism to send the gripping mechanism A gripping mechanism control unit that controls the operation of the gripping member, a gripping opening detection unit that calculates the size of the gripping opening formed by the plurality of gripping members by detecting the advancing / retreating position of the gripping member that can be moved forward and backward, A gripping method using a gripping device including a gripping detection unit that detects that a plurality of gripping members grips the object to be gripped and generates a detection signal,
The gripping mechanism control unit is set with a plurality of motion control values of the gripping member that can be advanced and retracted to operate the gripping mechanism, and the size of the gripping opening in each of the motion control values is set to the gripping opening. A calibration data generation step for generating calibration data calculated by the detection unit and representing the relationship between the motion control value in the gripping mechanism and the size of the gripping opening;
A calibration data storage step for storing the calibration data generated in the calibration data generation step,
After performing the calibration data generation step and the calibration data storage step,
Based on the shape information of the object to be grasped, a target value of the size of the grasping opening for grasping the object to be grasped is determined,
Generates motion control value data for the gripping member that is capable of advancing and retreating of the gripping mechanism for changing the size of the gripping opening until the target value is reached, and sends the operation control value data to the gripping mechanism control unit. A gripping step of gripping the object to be gripped by monitoring the generation of the detection signal by the grip detection unit, and stopping the advancement / retraction of the grip member that is enabled to advance / retreat after the generation of the detection signal. A gripping method characterized by:

Images