JPS63174888A - Method of controlling robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a method of controlling a robot so that the robot can continue to operate completely from an intermediate stop.

BACKGROUND OF THE INVENTION Conventionally, relative encoders, which are inexpensive and easy to handle, have often been used to detect the position of robots.

It has been conventionally practiced to stop a robot using a relative value encoder mid-motion and then continue the motion again under conditions where the power supply is not stopped during the robot's stop. However, once the power is turned off while the robot is stopped, the arm position of the robot changes because a return-to-origin operation is required before continuing the operation. If the continuous motion is started at this point, the robot will start moving directly toward the target point of the continuous motion. FIG. 4 shows the above-mentioned example. A Cartesian coordinate type robot 1 and a chuck 2 equipped at the tip are driven by a numerical control device 3, and a workpiece 4 is
Translated from point to point 22. At this time, in order to avoid the obstacle 6, chuck 2 passes through points PIa and P2a in order.
control so that it passes. When this robot 1 is stopped midway at point P2a and continues its operation again, if the power is not stopped while the robot 1 is stopped, it will follow the path shown by the solid line, and if the power is stopped while it is stopped, it will take the path shown by the broken line. Move to the next 22 target points. Note that 0 is the machine origin.

The above example uses a relative encoder for the arm position measurement device, but if an absolute encoder or resolver is used, an external force will be applied to the robot arm while it is stopped, and the state of the arm will change. Then, when the continuation motion is performed again, the robot starts moving directly from that state toward the target point of the continuation motion.

Problems to be Solved by the Invention However, in the above midway stop control method, the operation after the midway stop moves directly toward the target point of the continued operation regardless of whether or not the power supply is stopped. Even if there is an obstacle along the movement path, as shown by the broken line, the robot ignores this and moves. For this reason, there is a problem in that the robot itself, peripheral equipment, etc. are damaged, and complete continuous operation is impossible.

Therefore, the present invention is a control method that allows a robot to continue its complete operation regardless of whether or not the power is stopped after the robot is stopped midway.

Means for Solving the Problems In order to solve the above problems, the method for controlling a robot to stop halfway and return according to the present invention updates and stores arm position information and external output signal information when the robot stops halfway, It is determined whether or not there was a power outage during the mid-stop, and only when the power is stopped and the operation is continued, the memorized mid-stop point is set as the operation target point after the return-to-origin operation, and the stored mid-stop point is set as the operation target point after the return-to-origin operation. In this control method, after moving by an operation opposite to the origin return operation, the controller returns to a state in which an external output signal is stored and starts a continuation operation.

Operation The present invention uses the above-mentioned means, so that when a robot using a relative value encoder is temporarily stopped and the power supply is temporarily stopped, the continued operation is as follows: When performing an operation, it moves to the halfway stop position by the opposite operation, restores the state of the external output signal,
Continuation operation is started after the state is the same as when it was stopped midway.

Furthermore, if the power supply is not stopped, the continuous operation is directly started since there is no change in the state of the robot arm.

As a result, the robot can continue to operate completely without damaging itself or its peripheral equipment, regardless of whether or not the power supply is temporarily stopped while the robot is stopped midway.

EXAMPLE Hereinafter, a method of controlling a robot to return from a mid-stop stop according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a flowchart illustrating the main points of a method for controlling a robot to return from a mid-stop in an embodiment of the present invention. Second
The figure shows the configuration of a numerical control device and its peripheral equipment that make this control method possible. In FIG. 2, 1' is a Cartesian coordinate robot, 6 is an arm position detector, 3 is a numerical controller, 7 is a central processing unit (hereinafter abbreviated as CP u),
8 is a storage device, and 9 is a robot drive control device.

Hereinafter, an embodiment will be described according to the flowchart of FIG. 1 while referring to FIG. The CPU 7 inside the numerical control device 3, which received the intermediate stop signal in step 1, analyzes the signal and instructs the drive control device e to stop the robot 1 in step 2. At this time, the CPU 7 stores the state of the arm at the time of stop in the storage device 8 from the position information obtained from the arm position detection device 6 in step 3. At the same time, in step 4, the state of the external output signal from the numerical control device 3 at the time of stopping is also stored in the storage device 8. Next, the CPU 7, which has received the activation signal again in step 6, determines from the state of the storage device 8 whether or not the power supply has been stopped at least once during the mid-stop (step 8). Based on this condition judgment, if the power supply has not stopped, step 15
to continue operating immediately. Further, if the power supply has been stopped once or more, the CPU 7 instructs the drive control device 9 to return the robot 1 to the origin in the order of the Z-axis, Y-axis, and X-axis (steps 7 to 9). After this, CPU7 performs step 3.
The amount of movement of each axis when returning to the origin from the intermediate stop position stored in step 1 is calculated (step 1o). Based on the calculation result, the CPU 7 is driven so as to move to the beginning of the X-axis, Y-axis, and 2-axis in order to perform the operation opposite to the origin return operation, and complete positioning at the intermediate stop position memorized in step 3. A command is issued to the control device 9 (steps 11 to 13). When the movement to the intermediate stop position is completed, the CPU 7
restores the state of the external output signal stored in step 4. After reproducing the halfway stopped state in this way, the continued operation is started in step 15.

FIG. 3 shows the movement of the arm tip of the robot 1 according to this embodiment. It can be seen that the trajectory according to the conventional control method shown by the broken line intersects with the obstacle 6, whereas the present embodiment shown by the thick solid line faithfully continues the operation from the halfway stop point. Incidentally, P2b is the position to which point P2a moves due to external force being applied while the power supply is stopped. ' As described above, according to this embodiment, even if the power supply is temporarily stopped during a mid-stop, the system returns to the mid-stop position from the home return position through the reverse path of the home return operation, and the mid-stop state is restored. Since the continuation operation is performed after reproducing the motion, complete continuation operation can be performed without damage caused by obstacles or the like.

Effects of the Invention As described above, in the case where the power supply is temporarily stopped while a robot using a relative value encoder is stopped midway, the robot moves from the home return position to the midway stop position through a path opposite to the home return operation. By returning and performing complete continuous operation,
Although it uses a relative encoder, it is capable of continuous operation that is equivalent to or better than a robot that uses an absolute encoder or resolver, and when moving from the origin, it is safer because it takes the opposite path to the return-to-origin operation. expensive. Also, since it uses a relative encoder, it can be realized at low cost.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an overview of the robot control method according to the first embodiment of the present invention, FIG. 2 is a block diagram of a system that enables the control method shown in FIG. 1, and FIG.
FIG. 4 is an explanatory diagram showing the movement of the robot according to the control method shown in FIG. 1, and FIG. 4 is an explanatory diagram showing the movement of the robot according to the conventional control method. 1...Robot, 3...Numerical control device, 6...Arm position detection device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 × Figure 4

Claims (1)

[Claims of Claims] A control method in which a robot continues to operate from a state where the robot is stopped midway, comprising: (1) receiving a signal to stop the robot midway; (2) executing step (1) and stopping the robot; a step of reading and storing the position of the robot arm, (3);
Storing the state of the external output signal when step (2) is executed; (4); Receiving a signal to start continuous operation; (5); After executing step (3), step (4)
(6), executing step (5) and continuing the operation if the power has not stopped, (7), step ( Step 5) to perform a return-to-origin operation when the power supply is stopped; (8), which is the opposite of the arm operation assuming that the return-to-origin operation is to be performed from the position memorized in step (2). Step (9) to move the arm from the origin to the position memorized in step (2), step (3) after executing step (8).
The step of restoring the state of the external output signal memorized in (
10) A method for controlling a robot, comprising the following steps: performing a continuous operation after performing step (9).