JPH0683982B2 - Robot hand - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot hand, and more particularly to a robot hand configured to prevent damage of a chuck claw engaging with a work.

2. Description of the Related Art In the process of automatically supplying a work, such as a casting, to a machine tool, when a box-shaped pallet with an opening at the top is transported near a conveyor that supplies the work to the machine tool, the robot The arm is operated, and the robot hand attached to the end of the arm chucks the work in the pallet and transfers it to the conveyor.
A large number of works are stacked in multiple stages in the pallet via a floor plate, and the robot captures the work with an imaging camera from the top of the pallet and outputs the work position data (X, Y data) from the image processing device. The robot hand is operated based on the data to take out the work from the pallet.

Problems to be Solved by the Invention For example, when the work shape is a bowl shape with an opening at the bottom and has a through hole in the upper part and it is not possible to grasp from the outer circumference, the chuck claw at the lower end is inserted into the above through hole as a robot hand. Then, a device having a structure that opens outward and engages with the through hole is used. However, in the work of the above shape, the through hole as the engaging portion is provided in the upper part of the work. Therefore, when the work is placed in the upside down direction, there is no space below the through hole. I can't king. However, if the shape of the upper side of the work is substantially the same as the shape of the lower side of the work, the imaging camera of the image processing apparatus cannot identify that the work is placed in the opposite direction. Therefore, even if the work is placed in the opposite direction, the robot hand operates normally and the chuck claw is inserted into the through hole through the bottom opening of the work. Therefore, in the conventional robot hand, even if the work is placed in the opposite direction, the chuck claws pass through the through holes, and as a result, the chuck claws collide with the floor plate on which the work is placed, and There is a problem that the nail and the robot hand itself may be damaged.

Then, this invention aims at providing the robot hand which solved the said subject.

Means for Solving the Problems According to the present invention, a plurality of members that are inserted into a hole formed in the wall portion of a work provided with a wall portion that covers an internal space, are opened to the outside, and engage with a peripheral portion of the hole. Chuck jaws, first detecting means provided below the chucks so as to pass through the hole of the work and enter the space before the chuck jaws, and the chuck jaws. After passing through the hole of the work, the second detection means for contacting the upper plate of the work and detecting that the chuck claw has reached a position where it can be engaged with the hole of the work, Drive means for driving the chuck claw in the opening direction to engage with the peripheral portion of the hole when the detection signal from the second detecting means is output.

Action When the detection signal is not output from the second detection means but the detection signal is output from the first detection means, it can be determined that the work is inverted, and the detection signal is output from the first detection means. When the detection signal is output from the second detection means without it, it can be determined that the chuck claw has reached the position where it can be engaged with the hole of the work. Therefore, even when the vertical direction of the work cannot be identified by the image processing device, it is possible to prevent the chuck claws from colliding with the floor plate when chucking the work placed upside down,
Even if the movement position of the robot arm is deviated, or even if an obstacle other than the work is placed in the pallet, the first detection means makes contact with the work or the obstacle and outputs a detection signal. It is also possible to prevent the chuck claws from colliding with a work or an obstacle. Therefore, even if the work is not placed in the correct orientation or the movement position of the robot arm is displaced, it is possible to prevent the robot hand or the robot arm from being damaged and perform the work chucking operation more accurately. You can

Embodiment FIG. 1 and FIG. 2 show an industrial robot to which an embodiment of a robot hand according to the present invention is applied.

In both figures, the industrial robot 1 is installed between a conveyor 4 to which a box-shaped pallet 3 on which a work 2 is placed is supplied and a conveyor 5 to supply the work 2 to a machine tool (not shown). , The works 2 in the pallet 3 are taken out one by one and transferred to the conveyor 5. The industrial robot 1 is a cylindrical coordinate type robot, and has a base 7 fixed to a floor 6 and an arrow A on the base 7.
The swing table 8 is provided so as to be rotatable in the direction, the arm body 10 is moved up and down in the direction of arrow B by being guided by the pair of guide members 9a and 9b standing on the swing table 8, and the arm body 10 can be expanded and contracted. And an arm 11 provided.

A ball screw mechanism (not shown) that is screwed into the male screw 12 on the revolving table 8 is provided in the arm body 10, and the arm body 10 is driven by an actuator 14 supported by a column 13 to rotate the male screw 12. It goes up and down by doing. Further, the arm body 10 is provided with an actuator 15 for sliding the arm 11 in the direction of arrow C.

At the tip of the arm 11 via an L-shaped bracket 16,
Robot hand 17 extending downward and robot hand
An actuator 18 that rotationally drives 17 as a vertical axis is provided. Robot hand 17
Has a shape extending upward and downward so that the work 2 placed on the bottom 3a of the pallet 3 can also be chucked.

At the lower end of the robot hand 17, a chuck 19 having a chuck claw 19a that engages with the work 2 is provided. An imaging camera 20 connected to the image processing apparatus 20A is installed above the pallet 3 so as to image the work 2 placed on the pallet 3.

Reference numeral 21 denotes a control device, which operates each operation unit of the industrial robot 1 based on the data of the work position imaged by the imaging camera 20 to transfer the work 2 in the pallet 3 to the conveyor 5.

The control device 21 includes a CPU 21A, a memory 21B that stores data such as the work placement positions H ₁ , H ₂ , and H ₃ , and a robot hand 17 according to detection signals from a detection mechanism 26 and a work detection member 32 described later. And a robot hand driving means 21C for moving the robot up and down or stopping. Further, an alarm device 33 is connected to the control device 21, and when there is an abnormality in the work chucking process, as will be described later, the alarm device 33 gives an alarm to inform the operator of the abnormality.

Here, the shape of the work 2 will be described. As shown in FIGS. 3 (A) and 3 (B), the work 2 is formed in a bowl shape having an opening at the bottom, the side surface 2a is inclined, and the upper portion 2b is formed with a large-diameter first through hole 2c. , And a small-diameter second through hole 2d. Therefore, the work 2 has a space 2e formed therein, and is placed with the peripheral edge 2f as the bottom surface.

That is, as shown in FIGS. 4A and 4B, the works 2 are placed on the floor plate 22 and stacked in a plurality of stages (three stages in this embodiment). At this time, the work 2 is placed so that the upper portion 2b having the through holes 2c and 2d faces upward.

Therefore, when the robot hand 17 chucks the work 2, since the peripheral side surface 2a of the work 2 is inclined, the robot hand 17 does not grip the outer periphery of the work 2 but is punched in the upper portion 2b. Chuck claw 19 in the first through hole 2c
Engage a.

The height position of the upper part 2b of each stacked work 2 in FIG.
H ₁ , H ₂ , and H ₃ are stored in the memory 21B in the control device 21, and the industrial robot 1 transfers the work 2 from the uppermost stage (height H ₃ ) in order.

Here, the configuration of the tip portion of the robot hand 17 will be described with reference to FIG. In FIG. 5, a chuck 19 has three chuck claws 19 when a piston (not shown) of an actuator (driving means) 23 moves up and down by supplying compressed air.
At the same time, a is closed and displaced in the opening direction.
Since a mechanism for transmitting the piston displacement to the chuck claw 19a is well known, its description is omitted here.

As shown in FIG. 6, the chuck claws 19a are provided on the lower end surface 19b of the chuck 19 at intervals of 120 degrees, and the actuator 23
When the piston moves downward, it is displaced in the direction of arrow X ₁ , and when the piston moves upward, it is displaced in the direction of arrow X ₂ . In addition, the chuck claw 19
The opening operation of a is detected by moving the detected member (made of metal) 23b provided on the piston rod 23a integral with the piston downward to a position close to the proximity sensor (for example, high frequency oscillation type proximity sensor) 24. . And the actuator 23
The piston is stopped by stopping the supply of the compressed air by the detection signal from the proximity sensor 24, and the chuck claw 19a moves to the work 2
Is held at a position where it engages with the through hole 2c.

Reference numeral 25 is a guide member for guiding the inserting operation of the chuck claw 19a, and is arranged on the lower end surface 19b of the chuck 19 alternately with the chuck claw 19a. Further, the guide member 25 is a chuck claw 19a.
The outer surface 25a projects further downward and is inclined so as to be easily inserted into the through hole 2c, and the base portion of the outer surface 25a has a contact portion 25b that contacts the upper portion 2b of the work 2.

Further, a detection mechanism (first detection means) 26 is provided on the inner wall 25c of the one guide member 25 to detect that the work 2 is placed in the opposite direction or that the chuck claw 19a has approached another member. ing. The detection mechanism 26 is located below the chuck claws 19a and is provided on the bracket 27 attached to the inner wall 25c of the guide member 25, the rod 28a inserted into the through hole 27a of the bracket 27, and the lower end of the rod 28a. Abutting portion 28b and detected portion 28c provided on the upper end of rod 28a.
And a proximity sensor 30 (high frequency oscillation type proximity sensor) supported by a support member 29 extending from the bracket 27.
The detection member 28, which includes the rod 28a, the contact portion 28b, and the detected portion 28c, is located at a position that is normally moved downward in the arrow Y ₁ direction by the pressing force of the spring 31 and its own weight. The proximity sensor 30 is the detected member 28
It is detected that the detection member 28 is moving downward due to the proximity of c, that is, that there is no obstacle. The detected portion 28c also functions as a stopper that prevents the detection member 28 from falling.

Therefore, when the robot hand 17 approaches another member such as an obstacle when the robot hand 17 descends, the detection member 28 relatively moves up in the direction of the arrow Y _{2 while the} contact portion 28b contacts. This allows
Since the detected part 28c is separated from the proximity sensor 30, the proximity sensor 30 is switched to the off state.

A work detection member (second detection means) 32 detects the position of the upper portion 2b of the work 2, and outputs a detection signal when the chuck claw 19a passes through the through hole 2c of the work 2. That is,
The workpiece detection member 32 is attached to the chuck 19 by the bracket 19c.
When the contact portion 32a is supported by the side portion of the work 2 and the upper portion 2b of the work 2 contacts the rod 32b, the rod 32b relatively enters the cylinder 32c. A piston 32e biased by a coil spring 32d is provided on the upper end of the rod 32b, and a magnet (not shown) is embedded in the piston 32e. Piston 32e is chuck claw 1
When 9a passes through the through hole 2c, it approaches the magnetic sensor 32f. As a result, the magnetic sensor 32f detects that the work 2 is present and also that the chuck claw 19a is lowered to the chuckable position.

Next, the operation of the robot hand 17 having the above configuration and the operation of the industrial robot 1 in which the robot hand 17 is attached to the arm 11 will be described. When the industrial robot 1 operates, the CPU 21A of the control device 21 executes the processing shown in FIGS. 7 (A) and 7 (B).

First, a normal chucking operation will be described with reference to FIG. The pallet 3 is imaged by the imaging camera 20 of the image processing apparatus 20A, and the center position of the through hole 2c of each work 2 placed in the pallet 3 is read as the X and Y coordinates (step S1). Next, based on the X and Y coordinate data,
The operation command signal is transferred to each actuator of the industrial robot 1 (step S2). As a result, FIG. 1 and FIG.
As shown in the drawing, the arm body 10 is moved upward, the turning table 8 is rotated, and the arm 11 is slid to move the robot hand 17 above an arbitrary work 2. As shown in FIG. 4 (B), since the works 2 are stacked in three stages in the pallet 3, it is instructed to start from the height H ₃ of the uppermost stage (step S3). Then, the height H ₃ is set and the robot body 10 is lowered (step S
Four).

The detection mechanism 26 is moved until the lower end of the robot hand 17 descends to the height H ₃ position of the pallet 3 as the robot body 10 moves.
Make sure your proximity sensor 30 is on (step
S5). As will be described later, when the work 2 is inverted and placed on the detection mechanism 26 in the upside down direction, the detection member 28 comes into contact with the floor plate 22 as an obstacle and the proximity sensor 30 is turned off. It is provided to stop the robot hand 17 and prevent the chuck claws 19a from colliding. However, the detection mechanism 26 is not limited to the reverse placement of the work 2, and for example, there is an obstacle on the way to the work 2 or the robot hand.
When the position of 17 is largely displaced from the through hole 2c of the work 2, the detection member 28 can contact the obstacle or another member such as the upper portion 2b of the work 2 to detect them. This can prevent the chuck 19, the robot hand 17, and the industrial robot 1 itself from being damaged.

When the robot 17 reaches the position of height H _{3 while} the proximity sensor 30 of the detection mechanism 26 remains on in step S5, the lowering of the arm body 10 is stopped (step S6). in this way,
In the process in which the robot hand 17 descends to the position of height H ₃ , as shown in FIG. 8, when the workpiece 2 is placed in the normal direction, first, the detection member of the detection mechanism 26 at the lowermost end is detected.
28 enters the through hole 2c of the work 2. Then, the guide member 25 and the chuck claw 19a enter into the through hole 2c.

In step S7, it is confirmed that the work detection member 32 is turned on, and the presence of the work 2 is confirmed. When the sensor 32f of the work detection member 32 is turned on in step S7, the chuck claw 19a is located in the space 2e of the work 2 through the through hole 2c, and the work detection member 32 confirms the work 2 Therefore, the chuck claw 19a is operated by the driving force of the actuator 23 in the arrow X ₁ direction in FIG. 5, that is, in the opening direction (step S8).

As shown in FIGS. 5 and 8, when the chuck claw 19a reaches the position where it abuts the through hole 2c of the work 2 and engages the lower surface of the upper portion 2b, the detected member of the actuator 23 is detected.
23b is detected by the proximity sensor 24. Therefore, when the detection signal from the proximity sensor 24 is obtained, the chucking by the chuck claw 19a is confirmed (step S9). In the next step S10, it is confirmed whether or not the work detection member 32 is kept in the ON state even after the chucking. If the work detection member 32 is turned ON, the robot 2 together with the arm body 10 is kept chucking the work 2. Raise the hand 17 (step S11).

Work 2 chucked on chuck 19 is pallet 3
When the arm body 10 rises to a height position that exceeds the upper edge of the upper table, the revolving table 8 in FIG. 2 rotates about 90 degrees counterclockwise. At the same time, the arm 11 is expanded and contracted so that the work 2 is located above the conveyor 5. Next, the arm body 10 is lowered to place the work 2 on the conveyor 5, and the chuck 19 is closed to release the chucking (step S12). As a result, the work 2 is conveyed by the conveyor 5 and supplied to a predetermined machine tool (not shown).

In this way, one work 2 is transferred from the pallet 3 to the conveyor 5, one stroke of the work transfer operation is completed, and the industrial robot 1 is moved to the pre-work position shown in FIGS. 1 and 2. Restore (step S13). In the next step S14, it is determined whether or not the work 2 is present on the top floor board 22, and if the work 2 is recognized by the image processing apparatus 20A, the process returns to the step S1 to the above steps S1 to S13. The process of is repeated. However, if the work 2 is not recognized in step S14, the process proceeds to the next step S15, and the floor plate take-out robot (not shown) takes out the topmost floor plate 22 from the pallet 3.

When the work of taking out the floorboard 22 is completed (step S16),
The data of the descending height H of the robot hand 17 is updated from H ₃ to H ₂ (step S17). If the updated height H is 0, it is considered that all the works 2 in the pallet 3 have been taken out, and the transfer work of the works 2 to the pallet 3 is completed (step S18). However, when H = 0 is not satisfied in step S18, the process returns to step S4 and the processes of steps S4 to S16 are repeated as described above. In this case, in step S4, the height H ₂ is set and the robot hand 17 descends to a position where the second stage work 2 can be chucked. Therefore, each operation unit operates by the X and Y data based on the image from the image pickup camera 20 to transfer the second stage work 1 and the second stage work 2 respectively.

In step S5, if the detection mechanism 26 is turned off while the robot hand 17 reaches the predetermined height position, it is determined that there is an obstacle.
Is stopped (step S19). Further, while raising the robot hand 17 (step S20), the alarm device 33
A warning is issued to notify the operator that there is an obstacle.

When there are a plurality of works 2, the industrial robot 1 sequentially transfers the picked-up works 2. For example, since the work 2 placed upside down has a height of the upper portion 2b lower than that of the work 2 placed correctly, when the image pickup camera 20 images the pallet 2, the image of the work 2 placed correctly is clear. Therefore, the image of the work 2 placed in the opposite direction becomes slightly unclear. Therefore, the industrial robot 1 transfers the work 2 placed in the correct direction and then moves to transfer the work 2 in the opposite direction.

Here, a case where the work 2 is placed upside down and upside down as shown in FIG. 9 will be described.

The work 2 is placed on the floor plate 22 in the pallet 3 as shown in FIGS. 4 (A) and 4 (B), and among them, the upper portion 2b having the through holes 2c, 2d as shown in FIG. And may be placed in the opposite direction in which the peripheral edge 2f is located above. However, in the image pickup camera 20 that picks up an image from above the pallet 3, the shape seen from above is substantially the same regardless of whether the work 2 is correctly placed or the work 2 is placed in the opposite direction. It is not possible to determine whether or not.

Therefore, even if the workpiece 2 is turned upside down, the industrial robot 1 operates normally and lowers the robot hand 17 to a predetermined chucking position as described above. However, as shown in FIG. 9, when the work 2 is placed in the reverse direction, even if the lower end portion of the robot hand 17 is lowered to the position of height H ₃ , for example, the upper portion of the work 2
Since 2b is at the bottom, the work detection member 32 remains off in step S7.

In this case, the CPU 21A of the control device 21 executes the workpiece reverse placement detection operation shown in FIG. 7 (B).

That is, when the work detection member 32 is off despite the robot hand 17 descending to the predetermined height H ₃ , the process moves to step S31 to open the chuck 19, and then the work detection member 32 is turned on. It is again confirmed whether or not (step S32). This is because when the robot hand 17 is deviated from the center of the through hole 2c of the work 2 or the work 2 is tilted due to overlapping of the peripheral edge portions 2f of the adjacent works 2, the work 2 formed by casting is The work detection member 32 may not operate because the surface has irregularities. However, the work 2 may be moved by the opening operation of the chuck claw 19a of the chuck 19. Therefore, the work detection member 32 may be turned on after the chucking operation.

Therefore, in step S32, when the work detection member 32 is turned on after the chucking operation, the process returns to the step before step S9 and the processes of steps S9 to S13 are executed as usual.

However, even after the chucking operation, the work detection member
If 32 is off, move to step S33 and chuck 19
Close it and determine that there is no work 2 (step
S34). Therefore, when the work detection member 32 remains off despite the robot hand 17 reaching the height H ₃ , the robot hand 17 is raised without chucking the work 2 (step S35). Then, the number of missed vibrations is counted as +1 (step S36).

Since the above-mentioned operation may be caused by erroneously operating the robot hand 17 to a position where the work 2 is not placed, the number of times of idling is preset n times (in the present embodiment, for example, the third time). To see if (step S3
7). If it is n times or less, the process returns to step S1 and the processes of steps S1 to S13 are executed. However, step S
In 37, if there are n (three) idle vibrations, it is determined that the height setting is incorrect, and it is determined that there is no work 2 in the third stage (step S38). Change the H data from H ₃ to H ₂ (step S3
9).

Further, in step S40, the X and Y data of the center position of the through hole 2c of the work 2 is read, and the robot hand 17 is lowered to the height H _{2 of the second} step (step S41). Then, it is confirmed that the detection mechanism 26 is switched off (step
S42).

In the process of the robot hand 17 descending to the position of height H ₂ ,
As shown in the figure, when the work 2 is placed at the height H _{2 in} the opposite direction, the lower end portion of the robot hand 17 is the work 2
It will descend into the space 2e. Upper part 2b of work 2
Is on the bottom, the work detecting member 32 remains off, and the chuck claw 19a and the detecting member 28 further descend toward the through hole 2c. Then, the detection member 28 below the chuck claw 19a is inserted into the through hole 2c, and eventually the detection member 28 is inserted.
28 abuts the floor plate 22.

As a result, the detection member 28 moves relatively upward, and the detected member 28
c is separated from the proximity sensor 30, and the detection mechanism 26 is switched to the off state. In step S42, as described above, the detection mechanism 2
When 6 is turned off, the process proceeds to step S43 and the robot hand 17 is stopped. Therefore, it is possible to prevent the chuck claw 19a from colliding with the floor plate 22, and it is possible to prevent the chuck claw 19a, the robot hand 17, the arm 11 and the like from being damaged.
Therefore, even if the workpiece 2 is placed in the opposite direction, the occurrence of the damage or the like is reliably avoided, and the reliability of the industrial robot 1 is further enhanced.

In step S44, the robot hand 17 is lifted from the position of height H ₂ , and an alarm is issued from the alarm device 33 to inform the operator that the work 2 is in the reverse direction (step S4
Five).

Thus, when chucking the work 2, as described above, the work detection member 32 does not turn on even when the robot hand 17 descends to a predetermined height, and the number of idle swings without a work is n times (for example, 3 times). ), The detection mechanism 26 detects that the work 2 is placed upside down, so there is no chance that the work 2 placed correctly is wrongly determined to be upside down. In addition, it is possible to more reliably perform the work upside-down detection operation and improve the reliability of the chucking operation.

Although the work 2 having the shape shown in FIG. 3 is used in the above description, other shapes can be considered as the work shape. That is, the work may have any shape as long as it has a wall portion that covers the inner space of the work and the chuck claws are engaged with the holes formed in the wall portion.
Further, it is needless to say that the robot is not limited to the cylindrical coordinate type robot.

Further, in the above embodiment, the displacement of the detection member 28 is detected by the proximity sensor, but other sensors such as a reed switch and a magnetic sensor may be used, or a contact type such as a limit switch may be used. Of course, it is also good.

EFFECTS OF THE INVENTION As described above, in the robot hand according to the present invention, the work is inverted when the detection signal is not output from the second detection means but the detection signal is output from the first detection means. When the detection signal is not output from the first detection means but the detection signal is output from the second detection means, it means that the chuck claw has reached the position where it can be engaged with the hole of the work. Can be determined. Therefore, even when the image processing device cannot identify the vertical direction of the work, it is possible to prevent the chuck claws from colliding with the floor plate when chucking the work placed upside down, and the operation of the robot arm. Even if the position is deviated, or if an obstacle other than the work is placed on the pallet,
Since the first detecting means contacts the work or the obstacle and outputs the detection signal, it is possible to prevent the chuck claw from colliding with the work or the obstacle. Therefore, even if the work is not placed in the correct orientation or the movement position of the robot arm is displaced, it is possible to prevent the robot hand or the robot arm from being damaged and perform the work chucking operation more accurately. It has features such as being able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are a front view, a plan view, and FIGS. 3A and 3B of an industrial robot equipped with an embodiment of a robot hand according to the present invention. Plan view of work, longitudinal section, 4th
(A) and (B) are a plan view and a vertical sectional view showing a work placed on a pallet, FIG. 5 is an enlarged view showing an enlarged main part of a robot hand, and FIG. 6 is a robot hand. The bottom view of the chuck seen from below, FIGS. 7A and 7B are flow charts for explaining the processing executed by the control device,
FIG. 8 is a vertical cross-sectional view for explaining the operation when chucking a work placed in the correct direction, and FIG. 9 illustrates the operation when trying to chuck a work placed in the opposite direction. FIG. 1 ... Industrial robot, 2 ... Work, 3 ... Pallet, 4,5 ... Conveyor, 8 ... Turning table, 10 ... Arm body, 11 ... Arm, 17 ... Robot hand, 19 ...
… Chuck, 19a …… Chuck claw, 20 …… Imaging camera, 2
1 ... Control device, 22 ... Floorboard, 24 ... Proximity sensor, 25 ...
… Guide member, 26 …… Detection mechanism, 28 …… Detection member, 30…
… Proximity sensor, 32 …… Work detection member, 32a …… Contact part, 32f …… Magnetic sensor, 32e …… Piston.

Claims (1)

[Claims] 1. A plurality of chuck claws which are inserted into a hole formed in the wall of a work provided with a wall for covering an internal space, open to the outside, and engage with a peripheral portion of the hole. First detecting means provided below the chuck so as to pass through the hole of the work and enter the space before the chuck claw, and the chuck claw detects the hole of the work. Second detection means for contacting the upper part of the work and detecting that the chuck claw has reached a position where it can be engaged with the hole of the work after passing, and detection by the second detection means A robot hand comprising: driving means for driving the chuck claw in the opening direction when the signal is output to engage with the peripheral edge portion of the hole.