JPH1190871A - Synchronous control method for robot and conveyer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically adjust the speed of a conveyer by the number of workpieces and waiting time out of an operating range of a robot. SOLUTION: In a system detecting a workpiece 6 conveyed by a conveyer 3 by a visual sense device 7 to perform handling of the workpiece 6 by a robot 1, in the case that a number of the workpieces conveyed in a unit time is increased from an initialized set value, processing by the robot can not cover the increase, and when the workpiece left as not handled is generated, the speed of the conveyer is controlled so as to reduce the number of this not handled workpieces. In the case that the number of the workpieces conveyed in a unit time is deceased from the initialized set value, when a waiting time is generated in the robot, the speed of the conveyer is controlled so as to reduce this waiting time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the synchronization between a robot and a conveyor when a robot handles a moving object conveyed by the conveyor using a visual device such as an industrial television camera.

[0002]

2. Description of the Related Art Conventionally, in this type of system, after a robot grasps a workpiece on a conveyor, transports the workpiece to an installed container, and measures a cycle time until the robot returns to a standby position on the conveyor again. In this method, the conveyor speed is manually fine-tuned so that the workpiece can be gripped at the same position and close to the time of one cycle. In this type of system, the speed of the conveyor is
Often a certain value is given. In this case, if the number of workpieces increases, the processing of the robot cannot catch up, and it is necessary to stop the conveyor once, perform the processing, and manually adjust the speed of the conveyor again. Further, if the number of works decreases after the conveyor speed is set to be constant according to the number of works to be conveyed, a waiting time occurs until the robot grasps the next work. For this reason, it was necessary to manually adjust the speed of the conveyor again to increase the processing efficiency.

[0003]

Therefore, in the above-described conventional method of adjusting the conveyor speed synchronized with the robot,
When the processing capacity of the robot is exceeded due to an increase in the number of works conveyed by the conveyor or an increase in the conveyor speed, the first problem is that the conveyor must be temporarily stopped. Conversely, there is a second problem in that a decrease in the number of works to be conveyed or a decrease in the conveyor speed causes a waiting time for the robot, which lowers the processing efficiency.
In such a case, there is a third problem that the conveyor speed must be adjusted again. Furthermore, in the prior art, since the work area is fixed, when the transport speed and the number of objects change during the work, the number of objects included in the work area falls below the processing capacity of the robot, and the work is performed by the robot. There is a fourth problem that the working time cannot be shortened because waiting time may occur or the moving distance may be long. Therefore, an object of the present invention is to provide a control method for automatically adjusting the speed of a conveyor or expanding the work area of a robot according to the number of workpieces and the waiting time that are out of the operation range of the robot.

[0004]

In order to solve the above problems, a first aspect of the present invention is to provide a robot provided with a visual device and a conveyor for transporting a work, and the position and posture of the work to be transported. Is detected by the visual device, and in the synchronous control method of the robot and the conveyor that handles the workpiece by the robot, when the number of workpieces conveyed per unit time is larger than an initial set value, the processing of the robot cannot catch up with the workpiece. When the number of workpieces conveyed per unit time decreases below the initial setting value while controlling the conveyor speed so as to reduce the number of workpieces that have been missed, when the robot has a waiting time A conveyor synchronized with a robot, characterized in that the conveyor speed is controlled so that the waiting time is reduced. It is a method of controlling the A. In other words, the speed of the conveyor is automatically adjusted by the number of workpieces and the waiting time out of the operation range so that the number of workpieces that are out of the operation range and the waiting time of the robot are reduced due to the decrease in the number of workpieces conveyed per unit time and the waiting time of the robot. It is.
The above means eliminates the need to manually stop and adjust the speed of the conveyor as the number of workpieces increases or decreases, and reduces the waiting time when the robot handles workpieces, making the system operate more efficiently. It is possible to do.

According to a second aspect of the present invention, there is provided a robot having a visual device and a conveyor for transporting a workpiece, wherein the position and orientation of the workpiece to be transported are detected by the visual device, and the workpiece is detected by the robot. In the synchronous control method of the handling robot and the conveyor, even if the transfer speed or the number of objects changes during the work, the work area is limited so that the moving distance of the robot does not exceed a certain value, and it is included in the work area A synchronous control method for a robot and a conveyor, characterized in that a work area is extended when the robot has a work waiting time because the number of objects to be processed falls below the processing capacity of the robot. By the above-described means, an object to be conveyed by a conveyor is detected by a sensor, and in a system in which an industrial robot handles the object based on the detection result and the amount of movement of the conveyor, the conveyance speed and the number of objects during work are reduced. Even if it changes, the work area is limited so that the movement distance of the robot does not exceed a certain value, and the robot has to wait for work because the number of objects included in the work area falls below the processing capacity of the robot In such a case, the work area is extended to prevent unnecessary operation of the robot.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a specific embodiment of the first invention of the present invention will be described with reference to a flowchart of FIG. 1 and a schematic diagram of an apparatus for carrying out the method of the present invention in FIG. In FIG. 2, 1 is a robot, 2 is a robot controller, 3 is a conveyor, 4 is a variable speed motor for driving the conveyor, 5 is an encoder for detecting the amount of movement of the conveyor, 6 is a work, 7
Denotes a camera, 8 denotes an image processing device, and P denotes a pallet. The robot controller 2 has a drive control function of an external mechanism (referred to as an external axis) similarly to the axis of the robot, and it is preferable that the robot control apparatus 2 controls the variable speed motor 4 for driving the conveyor using this function (the amount of rotation is determined by the encoder Is fed back through). A description will be given of an example in which such a device performs an operation of transferring a work flowing on a conveyor onto a pallet. The present invention performs the following operation shown in FIG.

(Step 1) Image input is performed using a camera 7 that can image the conveyor 3.

(Step 2) The image input by the camera 7 is analyzed using the image processing device 8 to calculate the position of the work 6 present on the conveyor 3 at the current time.

(Step 3) The work position in the camera coordinate system calculated in step 2 is converted into a robot coordinate system.

(Step 4) In a system that follows a conveyor by image processing, a position where an image is picked up by a camera and a position where a robot can operate are often separated from each other, and position data of a work existing between the positions is listed. The processing for adding the work position in the robot coordinates calculated in step 2 to the list is performed.

(Step 5) Compared with the previous list data update, the current work position has moved by the amount of movement of the conveyor, so the amount of movement of the conveyor is added, and the position data list is updated to the one at the current time. Update to To perform this work, the conveyor pulse amount at the time of the previous list data update and at the current time is calculated, and the product of the previously calculated change amount in the robot coordinate system per one conveyor pulse is used to calculate the robot coordinate system. , And may be added to the position data of the list.

(Step 6) The list data is searched, and the operation range of the robot (line B in FIG. 1 indicates the upper limit of the operation range of the robot, and line C indicates the lower limit of the operation range of the robot. The range between the line B and the line C is the operation range of the robot.The mechanical movable range of the robot is A). If there is, go to step 7. If not,
Since the waiting time of the robot occurs, the process proceeds to step 9.

(Step 7) The work is followed, and a specified operation (in this example, the work is gripped and transferred to the pallet P) is performed.

(Step 8) At the waiting position, the robot checks whether the waiting time is less than a certain set value. If the waiting time is equal to or longer than the set value, the process proceeds to step 9. If the waiting time is shorter than the set value, the process proceeds to step 10.

(Step 9) A process for increasing the speed of the conveyor is performed, and the process returns to step 1.

(Step 10) It is confirmed whether or not there is a work located outside the operation range of the robot in the downstream area of the conveyor. If there is, go to step 11. If not, return to step 1.

(Step 11) A process for reducing the speed of the conveyor is performed, and the process returns to step 1.

As described above, the first aspect of the present invention realizes a lean operation by controlling the speed of the conveyor. Next, a second embodiment of the present invention will be illustrated and described. FIG. 3 is a flowchart of the embodiment of the present invention. The system configuration is the first
The invention is the same as that of the first embodiment, and the working example will be described below with the same example. However, in FIG. 1, B, B 'and B "are limit lines upstream of the work area of the robot, and C, C' and C" are limit lines downstream of the work area of the robot.

(Step 1) The work area 7 of the robot 1 is set wider on the conveyor 3.

(Step 2) The transfer of the work 6 is started.

(Step 3) When the vision sensor is working 6
Is detected. The robot controller 2 calculates the position of the detected work by acquiring the detection result and the conveyor position at the time of detection, and adds the calculated position to the work list including the data of the position and rotation angle of the work. Hereinafter, the robot controller 1 periodically acquires the detection result and the moving amount of the conveyor, and updates a work list in which data of all the works detected by the vision sensor is loaded in real time.

(Step 4) The controller searches the work list for data on a work in the work area (between the B and C lines). The search is performed sequentially from the downstream side of the conveyor. If there is data, the movement destination of the work is predicted to determine the operation position of the robot, and a work command is issued to the robot. If there is no data, the position of the work coming into the work area next is predicted, and the robot is made to wait on the upstream side of the work area. When the work enters the work area, a work command is issued. The robot 1 performs a work of grasping a work that has entered the work area (between the lines B and C) and transferring the work to a predetermined position on the pallet P in accordance with a command from the robot controller.

(Step 5) If the time required for the work handling work exceeds the average time of the work loading interval, the work area is narrowed within a range not to fall below a predetermined size (that is, the line B ′). −C ′ line).

(Step 6) If there is no work in the work area 7 and there is a waiting time for the robot in spite of the work 8 in the operation area 6, the work area is expanded (that is, B ″). Spread between line-C ").

(Step 7) Returning to step 4, the work is continued while adjusting the work area in the same manner.

As described above, the second aspect of the present invention realizes a lean operation by adjusting the work area of the robot. Further, it is also possible to extend the working area of the robot while controlling the speed of the conveyor by combining the first and second aspects of the present invention.

[0027]

As described above, the present invention provides a method of detecting the position of a moving work conveyed by a conveyor or the like via a robot device having a visual device by a visual device and handling the work by a robot. In this case, the control method automatically adjusts the speed of the conveyor so as to reduce the work drop-out and the waiting time of the robot, so that the conventional system can be operated more efficiently. In addition, even if the transport speed and the number of objects change during the work, the work area is limited so that the moving distance of the robot does not exceed a certain value. If the robot waits for work due to a decrease in the distance, the work area is expanded, thereby preventing useless operation of the robot and improving work efficiency.

[Brief description of the drawings]

FIG. 1 is a flowchart of the first invention of the present invention.

FIG. 2 is a diagram showing an example of an apparatus for implementing the method of the present invention.

FIG. 3 is a flowchart of the second invention of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot 2 Control board 3 Conveyor 4 Encoder for detecting the amount of conveyor operation 5 Variable speed drive motor 6 Work 7 Camera 8 Image processing device A Line indicating the operation area of robot B, B ', B "Upstream of robot operation range Side limit line C, C ', C "Downside limit line of robot operation range P Pallet

Continuation of front page (72) Inventor Tetsuya Takahashi 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Yaskawa Electric Corporation

Claims (6)

[Claims] 1. A synchronous control method for a robot and a conveyor, comprising: a robot provided with a visual device; and a conveyor for transporting a workpiece, wherein the visual device detects a position of the workpiece to be transported, and handles the workpiece by the robot. In the above, when the number of works conveyed per unit time is larger than an initial set value, control is performed to reduce the speed of the conveyor, and when the number of works conveyed per unit time is smaller than an initial set value. Is a method for controlling the synchronization between a robot and a conveyor, wherein the control is performed to increase the speed of the conveyor. 2. The method according to claim 1, wherein the control for reducing the speed of the conveyor is performed when a workpiece is missed by the robot. 3. The synchronous control method for a robot and a conveyor according to claim 1, wherein the control for increasing the speed of the conveyor is performed when a waiting time of the robot occurs. 4. A synchronous control method of a robot and a conveyor, comprising: a robot provided with a visual device; and a conveyor for transporting the workpiece, wherein the position of the workpiece to be transported is detected by the visual device, and the robot handles the workpiece by the robot. In the above, when the number of objects included in the work area is less than the processing capacity of the robot, the work area of the robot is extended, and when the number of objects included in the work area exceeds the processing capacity of the robot, the robot A synchronous control method of a robot and a conveyor, characterized in that the work area of the robot is reduced. 5. The method according to claim 4, wherein the process of expanding the work area of the robot is performed when a workpiece is missed by the robot. 6. The method according to claim 4, wherein the process of reducing the work area of the robot is performed when a waiting time of the robot occurs.