JPH0325803B2 - - Google Patents

Description

[Detailed description of the invention] (Prior art) Driven by a servo motor, servo valve, etc.
A variety of highly versatile robots have been developed that have multiple axes of motion that operate according to instructions from a controller, and are proving effective in saving labor and streamlining work. For example, there is a system as disclosed in Japanese Patent Application Laid-Open No. 182707/1983. However, there are still many issues with this control system, and it is difficult to say that the performance of this highly versatile robot mechanism is fully utilized. I'm not used to it. The present invention provides a control system that improves the current situation.

In order to operate a robot, it is necessary to instruct the robot about the operating point, and there are methods that use teaching, methods that use numerical commands, and methods that allow both teaching and numerical commands. This method is also possible.

(Problems to be Solved by the Invention) The purpose of the present invention is to rotate workpieces to a machine using a robot, depalletize to take out workpieces stacked in a magazine one by one during assembly work, and reverse In addition, palletizing work is carried out, in which workpieces that have been machined or assembled are stacked one by one in a magazine.
This must be done reliably and quickly.

The problems will be explained with reference to FIG. 1 as an example of a robot system that performs depalletizing and palletizing.

In the system shown in Figure 1, robot 1 has hand 2.
The workpieces stacked vertically in the magazine 3 are grasped one by one and loaded into the machine 4. The workpiece that has been processed by the machine 4 is transferred to the machine 4 by the hand 2 of the robot 1.
From there, they are removed and stacked vertically in similar magazines.

When performing vertical palletizing and depalletizing as described above, generally the position of each workpiece is shifted by the height of the workpiece in the vertical direction of the workpiece. However, in general, the workpieces are not made with such high precision, and even if they are made, foreign objects may get caught between the workpieces, and they are not actually stacked at even intervals. Because the errors are accumulated, when the hand completes positioning, the hand often pushes against the workpiece or fails to grip the workpiece.

(Structure of the Invention) In view of the above-mentioned current situation, the present invention provides a detector for detecting a workpiece at the tip of the hand, and utilizes this detector to ensure the above-mentioned palletizing operation and depalletizing operation at high speed. It is something that is done. Moreover, it is possible to perform the process reliably no matter what amount of workpieces are initially contained in the magazine. Moreover, the number of operating points required to be memorized for this task is very small.

(Example) Figure 2 shows the movement of the magazine and the hand relative to the magazine during vertical depalletizing and palletizing as in the system shown in Figure 1, and is performed using the hand shown in Figure 3. I can do things. The hand can move within a groove 20a vertically attached to the magazine 20, and can grip the workpiece 5 in the magazine. In Figure 2, ◎
The points indicated by are the gripping positions during depalletizing, and ○× are the release positions during palletizing.

A detector 7 is attached to the hand, and when the detector 7 detects the workpiece 5 and a workpiece detection signal is input, the hand can grasp the workpiece 5 by immediately stopping or by moving a little. The detector 7 is mounted so that it can be used.

In the case of depalletizing, it is unknown how far in the magazine the workpieces are stacked, so when the workpieces are detected by the detector 7, the topmost part is moved at a relatively slow speed that allows the workpieces to be stopped without colliding with the workpieces. Move your hand from there to the bottom. In FIG. 2, the area that moves at this speed is represented by a dotted line. When the robot moves to a place where the workpieces are stacked, the detector 7 detects the workpieces, and a signal is input to the robot controller. The robot controller receiving this signal input stops the movement of the hand. Stopping the movement of the hand due to this signal input can be done using a very general technology using LSI such as CPV and I/0 port used in the controller, so we will not go into details. .

After stopping movement, the robot controller will
The current position is stored in the position memory by an automatic teaching command. It goes without saying that the robot controller always remembers the current position of the hand, and storing this in a position memory is an extremely common technique, so we will not discuss this in detail. After self-teaching, the hand can grip the workpiece extremely reliably.

The self-taught position data is used to quickly perform the next workpiece removal operation. First, since there is no workpiece already at the first workpiece removal point designated by the position data, there is no problem at all even if the band is moved at high speed to that position. Then, as in the beginning, move it toward the bottom at a speed that allows it to stop without collision, and then perform exactly the same operation as in the beginning. The high-speed movement operation point for the next workpiece take-out operation is self-taught. As the position of the workpiece to be taken out becomes deeper each time, the distance to be moved becomes longer.
Only the high-speed movement distance due to self-teaching becomes longer, so the overall time does not increase by that much.

If the movement target position T1 of the robot hand is not below the position where it can grip the lowest workpiece,
The workpiece at the bottom cannot be gripped reliably. Therefore, the final operation is to confirm that there is no workpiece, and when it is confirmed that there is no workpiece, the empty magazine is moved to another location and another magazine containing a workpiece is brought. Alternatively, the process moves to another specified operation, such as similarly starting to take out workpieces stored in other magazines. Such operations are also generally controlled by a computer. Since this can be done using the same means as the conditional jump function, we will not go into details.

In the case of palletizing, it is unclear at first how far into the magazine the workpieces are stacked, so
It is necessary to check the amount of the workpiece without gripping it. Fig. 2 shows the operation of palletizing O.The basic operation is when a workpiece is detected, it is moved to the target position P2 where the lowest workpiece should be at a speed that allows it to stop without collision, and then it is detected and stopped. The position is taught by the self. After that, the robot returns to the position where the work is placed in order to grasp the work, and then causes the hand to grasp the work, moves it at high speed to a point above the self-teaching point by T3, and then moves the hand. Release and let the workpiece fall. T3 is a distance that takes into account variations in the height direction of the workpiece accuracy, etc., and is selected so that even if the workpiece is released and dropped from a position shifted by this distance, the workpiece will not be scratched. The self-teaching point and T3 are treated as vectors in the controller data, and shifting is performed by adding vectors.

In the operation of palletizing O in Fig. 2,
This is a case where the magazine is initially empty, and the workpiece is not detected even when the target point is reached. At this time, unlike when detection has stopped, from P2 to T3
A vector calculation is performed to shift a shorter distance by the pitch T2 of one workpiece, and the point obtained as a result is set as a target value, and after moving at high speed in the same manner as described above, the workpiece is dropped.

After the hand is released, when the hand detects the workpiece, it moves toward P2 at a speed that allows it to stop without collision, detects the workpiece, stops, self-teach its stopping position, and then returns to the self-teaching point. Then, calculate T3 as a vector and use this result as the next workpiece release position. Further, when the workpieces are fully stacked, the detector 7 moves the workpieces at high speed to a position P3 where the workpieces can be detected. If the workpiece is not detected even after reaching the target position P3, the magazine is not full, and the next palletizing operation is possible, so a similar workpiece stacking operation is performed. In this way, after the workpieces are stacked to the full in the magazine, the height of the stacked workpieces is detected and self-taught, and when you try to move at high speed to detect the workpieces with P3 as the target, the workpieces have already been detected. , workpieces can be detected without moving. By this, it is possible to detect that the magazine is full of workpieces, and it is possible to perform operations such as replacing the workpieces with the next magazine or palletizing them into another magazine.

FIGS. 4 and 5 are explanatory diagrams of depalletizing and palletizing operations when the workpieces are kept horizontally close together, and a diagram of the hand used therein, respectively.

Two detectors are attached to the hand in FIG. 5, detector 8 is a detector used during depalletizing, and detector 9 is a detector used during palletizing.

The depalletizing operation differs from the depalletizing operation shown in Figure 2 in that the operating direction is changed from vertical to horizontal, and in particular, the detection movement operation is different in that linear movement is required. The operation sequence is exactly the same as that in FIG.

Straight line movement is a commonly performed operation and does not require a deep explanation.

The palletizing operation is performed using the detector 9. First, grasp the workpiece, aim at position P5 where the leftmost workpiece is placed, and use linear interpolation to detect the workpiece without colliding with it, bring it close to the detected workpiece, and detect the workpiece at a speed that allows it to stop. Move your hand.

In the palletizing process shown in FIG. 4, the magazine is initially empty, and the hand reaches the target point without stopping for detection. After reaching the target point, the vector
Vector calculation is performed on the position shifted by T5, and the workpiece is gripped and moved at high speed to the resulting position during the next palletizing. After the movement is completed, the robot moves toward P5 until it detects the detected workpiece at a speed that allows it to stop without colliding and in close contact with the detected workpiece. After the detection stops, the stop position is taught by itself. The self-teaching point is used to calculate the position shifted by the vector T5 and to find the next workpiece gripping high-speed movement point. After self-teaching, the hand moves at high speed toward point P6 until it detects the workpiece. P6 selects the position where workpiece detection will work reliably when the workpieces are fully loaded. If no workpiece is detected even after reaching P6, it is still possible to insert a workpiece, and the same palletizing process as described above is continued.

When the work was full, I set my goal to P6.
When the workpiece detection movement is performed, the workpiece has already been detected, so it is possible to know that the workpiece is full without moving it. This makes it possible to perform operations such as changing to the next magazine or palletizing to another magazine.

In vertical palletizing as shown in Fig. 2, if a detector capable of detecting workpieces one pitch below detector 7 can be attached to the hand, the work amount detection operation can be performed in the same way as in horizontal palletizing in Fig. 4. It is also possible to operate without it.

In the above-mentioned depalletizing and palletizing, the movement of the hand must be linear, and the spatial posture of the hand must also be constant.
In order to keep the spatial posture of the hand constant, when moving in the vertical direction, the Cartesian coordinate type, cylindrical coordinate type, and horizontal joint type (scalar type), all of which have vertical motion axes, can be used without any problems. It is. Even in robots with vertical joints, the technology to maintain a constant posture of a workpiece is already a well-known technology in the world.

When moving in the horizontal direction, the Cartesian coordinate type allows no problems at all, while the cylindrical coordinate type and horizontal joint type (SCARA type) provide a movement axis that rotates the hand in the horizontal plane, and the total horizontal rotation angle is This can be done by controlling so that it is always kept at 0. In addition, in such a control method,
It is also highly effective in applications where the detector is not located at the tip of the hand. For example, the resistor can be trimmed by holding a cutter with a hand, or it can be trimmed by a robot by inputting a signal indicating that the resistance value matches a target value from a resistance measuring device.

(Effects) As explained above, according to the present invention, palletizing and depalletizing operations using a robot can be carried out very reliably and at high speed, and the economic effects thereof are remarkable.

[Brief explanation of the drawing]

Figure 1 shows palletizing. FIG. 2 is a side view of a general robot system that performs depalletizing work, and shows vertical palletizing according to the present invention. FIG. 4 is an explanatory diagram of the movement operation when performing depalletizing work, and FIG.
The figure is a perspective view of the hand used during the work shown in FIGS. 2 and 4. In the figure, 1 is a robot, 2 is a hand, 3 is a magazine, 4 is a machine, 5 and 6 are works, and 7, 8, and 9 are detectors.

Claims (1)

[Claims] 1. A robot control method for palletizing and depalletizing workpieces by memorizing the operating position of the robot. When moving the workpiece, by moving the hand at high speed to the gripping position in depalletizing and to the workpiece release position a predetermined distance above the detection position in palletizing,
A robot control method characterized by speeding up the operation.