JPS62190502A - Origin calculating method of industrial robot - Google Patents

Abstract

PURPOSE:To avoid a danger of interference between a robot and a work or the like by limiting the extent of movement of the robot to a value near the operation range of an origin a confirmation switch when original calculation is executed. CONSTITUTION:It is decided by a microcomputer 1 whether an origin confirmation switch 8 provided at the origin is turned on or not. When an origin calculation switch 10 is turned on after confirming that the switch 8 is turned on, the robot starts to move in the plus direction. When the robot gets out of the operation range of the original confirmation switch 8 after starting to move in the plus direction, that is, when the origin confirmation switch 8 is turned off, the microcomputer 1 instructs a servo motor 4 to rotate in the opposite direction, and the robot starts to move in the minus direction. While the origin confirmation switch 8 is not turned off, that is, while the robot is moved in the plus direction within the operation range of the origin confirmation switch 8, the rotation of the motor is not inverted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for finding the origin of a numerically controlled industrial robot when starting the robot.

(Prior art and its problems) Conventionally, in industrial robots that perform positioning using pulse encoders, the robot is controlled by a microcomputer based on a program stored in an internal memory circuit such as a microcomputer. A command pulse corresponding to the amount of movement is transmitted. This command pulse is D
The command pulse was converted to a voltage value corresponding to the command pulse via a /A converter, and the voltage output from this D/A converter was amplified via a servo amplifier, allowing the robot to move by rotating the servo motor. In this case, the rotation of the servo motor is detected by a pulse encoder, and the position pulses output from the pulse encoder are fed back into the microcomputer via an up-down counter, and the position pulses that have been input from the command pulse and the pulse encoder are The microcomputer is configured to issue a stop signal when the command pulse and position pulse become equal.

In this type of numerically controlled industrial robot, the absolute position at which the robot stops when 'FLg is turned off is not determined, and when starting the robot,
It was necessary to always return to the origin when the power was turned on.

In other words, in order to accurately stop the robot at the commanded position using the command pulses commanded by the microcomputer, it is necessary to determine the starting point of the pulse encoder's pulse generation, and the pulse encoder outputs the Since the stopping position of the robot is determined by comparison with the position pulse, the pulse encoder's pulse Jl [origin detection to determine the starting point (origin) is indispensable.

Conventionally, for example, when the power is turned on, the robot moves to A shown in Fig. 5.
Assuming that it is at the point, in this state, in order to automatically perform the home search, turn the home search switch to OFF.
When N is selected, the robot starts moving from point A in the direction of the origin confirmation switch that has been installed at the origin. When the robot has moved to point B, which is the operating range of the origin confirmation switch,
The origin confirmation switch is turned ON and the direction of movement of the robot is reversed. Therefore, the robot switches from moving in the minus direction to moving in the plus direction, and when the origin confirmation switch is turned off by passing through the 0 point, the robot changes direction again and moves in the minus direction. Then, the vehicle enters the operating range of the origin confirmation switch again and passes through point D, thereby turning on the origin confirmation switch. After the passage of this point D is confirmed by the origin confirmation switch, the first two-phase pulse is emitted from the pulse encoder to the microcomputer.
The rising position of this two-phase pulse is set as the origin, and the counter for counting the pulses of the pulse encoder is cleared. Therefore, from this point on, the pulses output from the pulse encoder are counted by a counter, fed back into the microcomputer, and the command pulse is compared with the position pulse input from the pulse encoder in the microcomputer.
The robot is stopped at a predetermined position.

However, in this conventional home finding method, when the robot is started, that is, when the power is turned on, the robot is automatically moved in the direction of the home confirmation switch, regardless of the position of the robot. Since the configuration was such that it was possible to find the origin, for example, if the robot was stopped inside the workpiece and tried to automatically find the origin, the robot would interfere with the workpiece and cause damage to the workpiece or the robot. Severe damage will occur to the robot. Furthermore, since the movement path of the robot when finding the origin cannot be predicted, there is a problem in that the origin finding operation is dangerous.

(Means for Solving the Problems) The present invention is capable of automatically performing origin search only when the robot is near the origin, and when the robot is located far from the origin. The purpose of this is to configure the system so that the origin search cannot be performed automatically, to minimize the amount of movement of the robot when performing the origin search, and to avoid risks such as interference between the robot and the workpiece. The gist of the system is to move the robot to a predetermined position based on the robot's position information fed back from the pulse encoder, and to move the robot to a predetermined position based on the robot's position information fed back from the pulse encoder. Only when the robot is within the operating range,
A method for finding the origin of an industrial robot is characterized in that the origin finding operation can be executed automatically.

(Function) When starting the robot, input tR and perform the home search. Only when the robot is located within the operating range of the home confirmation switch installed at the home, the home search can be executed. If the robot is located outside the operating range of the confirmation switch, it will not be possible to execute the home search even if you turn on the home search switch, and the amount of movement of the robot when performing the home search will be the same as the home position. Since it is limited to the vicinity of the operating range of the confirmation switch, dangers such as interference between the robot and the workpiece can be avoided as much as possible.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

First, a control device for a numerically controlled robot using a pulse encoder will be explained based on FIG.

In the figure, reference numeral 1 denotes a microcomputer, which has a built-in recording circuit and the like that records preprogrammed moving positions, moving speeds, moving accelerations, etc. of the robot. When the microcomputer 1 issues a position command pulse corresponding to the amount of movement of the robot, this position command pulse is incorrectly input to the D/A converter 2. D/A with
The converter 2 converts the input command pulse into an analog signal and outputs a voltage proportional to the position command pulse. The voltage output from the D/A converter 2 is amplified by the servo amplifier 3.

The voltage amplified by the servo amplifier 3 is input to the servo motor 4, and the servo motor 4 starts rotating.

The rotation speed of the servo motor 4 is detected by a tough generator 5 connected to the servo motor 4, and the detected rotation speed is fed back to the servo amplifier 3.

The servo amplifier 3 compares the rotation speed from the tough generator 5, which has completed feedback, with the command speed commanded from the microcomputer 1, changes the voltage to the servo motor 4 in order to match the voltage with the command speed, and starts the servo motor. Adjust the rotation speed of motor 4.

A pulse encoder 6 is further connected to the servo motor 4. This pulse encoder 6 emits three-phase pulse signals of A phase, B phase, and 2 phase as shown in Fig. 2 by the rotation of the servo motor 4. (with slits at different intervals) is used.

As the servo motor 4 rotates, the pulse encoder 6 generates position pulses, which are counted through the up/down counter 7 and fed back to the microcomputer 1. This pulse encoder
The position pulse input from 6 is compared with the command pulse in the microcomputer 1, and when the command pulse and the position pulse become equal, the microcomputer 1 issues a robot stop signal.

9 in the figure is an input board, which is a microcomputer-1
At the same time, an origin confirmation switch 8 and an origin finding switch 10 are connected in parallel to this input board 9.

That is, the origin confirmation switch 8 is constituted by a microswitch or the like, and is installed at the origin, which is the original starting position of the robot. On the other hand, the origin search switch f10 can be constituted by a push button switch or the like, and is an execution switch for executing the origin search of the robot.

Conventionally, when the origin search switch 10 is turned on, an execution signal for origin search is input to the microcomputer 1 via the input board 9, and the microcomputer 1 issues a signal to move the robot to the origin. ,
The servo motor 4 was rotated based on the signal.

In this example, the fourth
The program for finding the origin shown in the flowchart in the figure is fully stored. That is, in this example, when executing the origin search when the power is turned on, the microcomputer 1 first determines whether or not the origin confirmation switch 8 installed at the origin is turned on (step 1).
.

That is, it is confirmed that the robot is within the operating range of the origin confirmation switch 8. After confirming that the origin confirmation switch 8 is turned on, the origin search switch 10 is turned on.
By moving Ng (step 2), the robot starts moving in the plus direction (rightward in FIG. 3) (step 3). Note that when the robot is not within the operating range of the origin confirmation switch 8 and the origin confirmation switch 8 is turned off, the microcomputer 1 does not send a robot movement signal to the servo motor 4 even if the origin search switch 10 is turned ON. It does not emit any energy, and the robot cannot move.

When the robot starts moving in the positive direction in step 3 and is out of the operating range of the origin confirmation switch 8, that is,
When the origin confirmation switch 8 turns 0FFe (step 4),
The microcomputer 1 instructs the servo motor 4 to rotate in the opposite direction, and the robot starts moving in the negative direction (step 5). When the origin confirmation switch 8 is not turned off, that is, while the robot is moving in the plus direction within the operating range of the origin confirmation switch 8, reversal is not performed.

In addition, in this example device, since an incremental type is adopted as the pulse encoder 6, slits are formed at regular intervals with a 90° phase shift in the rotating disk that constitutes the pulse encoder 6. , A-phase, and B-phase pulses are generated, and the moving direction of the robot is detected by these pulses. Therefore, by determining the direction pulse from the pulse encoder 6, the moving direction of the robot can be switched between forward and reverse directions.

In step 5, the robot moves in the negative direction and enters the operating range of the origin confirmation switch 8 again, and the origin confirmation switch 8 is turned on (step 6), thereby detecting the ON state of the origin confirmation switch 8. Then, the first two-phase pulse is input from the pulse encoder 6 into the microcomputer-1. The rising position of this two-phase pulse becomes the origin. At this time, the up/down counter 7 is cleared to O.

In this state, the microcomputer 1 generates a position command pulse corresponding to a predetermined amount of movement of the robot, and the servo motor 4 is rotated in accordance with the pulse signal to move the robot to a predetermined position. The movement position is constantly fed back as a position pulse by the pulse encoder 6, and the robot stops at a predetermined position while being controlled.

Incidentally, FIG. 3 shows the movement state of the robot during the origin search shown in the flowchart of FIG. 4. That is, the robot needs to be located at point A within the operating range of the origin confirmation switch 8, and in this state the origin confirmation switch 10 is turned on. robot step 3
By moving in the positive direction, the origin confirmation switch 8 is turned off after passing point B, and the servo motor 4
Due to the reversal of , the robot starts moving in the negative direction in step 5 , and when it passes the 0 point, the origin confirmation switch 8 is turned on, and the pulse encoder 6 emits two-phase pulses.

In this example, when performing the origin search, it is essential that the robot is initially located within the operating range of the origin confirmation switch 8. If the robot is located at
Therefore, in performing the origin search, the movement range of the robot is limited to the vicinity of the operating range of the origin confirmation switch 8, and the robot moves only within an extremely limited range. Therefore, since the amount of movement of the robot is small when finding the origin, there is no fear of interference with workpieces, etc., and safety in the origin finding operation can be ensured.

(Effects of the Invention) The present invention moves the robot to a predetermined position based on robot position information fed back from a pulse encoder, and automatically moves the robot to a sensor position installed at the origin position when the robot starts. This is a method for finding the home of a numerically controlled industrial robot that has a home finding function that allows the home to be found automatically only when the robot is located within the operating range of a sensor such as a micro switch installed at the home. As a result, the origin search start position is extremely close to the origin, and the amount of movement of the robot during origin search is small, so there is no risk of interference between the robot and the workpiece, and the robot operation is safer. This has the effect of greatly improving sexual performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the robot control device, FIG. 2 is an output waveform diagram of the pulse encoder in FIG.
FIG. 4 is a flowchart for executing the origin search in this example, and FIG. 5 is a diagram showing the movement state of the robot during the conventional origin search, which corresponds to FIG. 3. 1... Microcomputer 2... D/A converter 3... Servo amplifier 4... Servo motor 5
...Tough generator 6...Pulse enhancer 7...Up/down counter 8...Origin confirmation switch 9...Input board 10
... Home search switch patent applicant Aichi Machine Industry Co., Ltd. agent
Patent Attorney Yoshihisa Shimizu Figure 2 Figure 3

Claims (1)

[Claims] Numerical control type with an origin finding function that moves the robot to a predetermined position based on robot position information fed back from a pulse encoder, and automatically moves the robot to the sensor position installed at the origin position when the robot is started. A method for finding the origin of an industrial robot,
A method for finding the origin of an industrial robot, characterized in that the origin can be automatically found only when the robot is located within the operating range of a sensor such as a microswitch installed at the origin.