JPS6128106A - Direct teaching type industrial robot - Google Patents

Abstract

PURPOSE:To attain stable arm position control without any compensating circuit at opeation by detecting a drive amount and an arm moving amount of a drive source at the front and rear stage of a transmission mechanism and controlling its deviation to zero so as to attain arm operation at teaching without using a clutch mechanism. CONSTITUTION:A motor 3 is stopped at teaching and when an arm 1 is energized clockwise, a transmission shaft is driven at an output of a gear reducer 5, and a pulse signal is outputted from a position detector 16 but no output is given from a position detector 15. A circuit 18 detects the deviation of the moving amount from an output signal of the detectors 15, 16, an analog signal corresponding to a deviation is fed to an amplifier 19 and the motor 3 is driven clockwise. On the other hand, a switch SW2 is turned off at running and the motor 3 is driven in a speed based on a speed command signal of a controller 10. Further, the switch SW1 is thrown to the position of output (a), an output signal of the detector 15 is fed to a device 10, the position control of the arm 1 is executed, no effect of the gear reducer is given to the detector 15, then stable control is attained and no compensating circuit is required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a direct teaching type industrial robot t4 that can directly teach with extremely small force.

[Conventional technology]

There are usually two methods for teaching industrial robots. The first method is called the remote teaching method, in which the operator holds a teaching box or joystick and teaches the robot while remotely operating it.The second method is called the direct teaching method or manual teaching method. This is a method in which the operator directly grasps the arm end, wrist, etc. of the robot whose driving force has been cut off, operates it, and teaches the robot.

By the way, the remote teaching method has the disadvantage that it is cumbersome to move the bot's arm in the desired direction because the switch or joystick on the teaching box is operated, and that teaching takes time. On the other hand, the direct teaching method has the advantage that the teaching time is extremely short and complex routes can be taught efficiently compared to the remote teaching method.

[Problem that the invention seeks to solve]

However, in the above-mentioned direct teaching type industrial robot, in order to move the considerably heavy robot arm manually, it is necessary to provide a clutch mechanism that disconnects the drive source from the robot arm during teaching. The structure is complicated and expensive. Furthermore, there are also problems with the control device as described below. That is, as shown in FIG. 2, it is necessary to install a position detector 2 for detecting the position of the robot arm 1 on the arm side that is downstream of the clutch 4 when viewed from the motor 3 that is the drive source. If a configuration like this is adopted, the position control system of arm 1 during operation (C playback) will be equipped with an extremely low rigidity reducer (in general, reducers used in industrial robots have low rigidity, and a spring is attached to the power transmission shaft). ) 5 and clutch 4
Because of this, there is a problem that the position control loop becomes extremely unstable and sometimes hunting occurs.

Therefore, as shown in the figure, state sensors 7 and 8 such as pulse encoders are provided on the motor 3 side and the arm 1 side, respectively, and these signals are processed and the position control loop VC
Some kind of compensation had to be made.

In this case, since the compensation circuit consisting of the condition sensor 7.8 and the processing circuit 9 needs to handle and compensate for extremely small signals, high precision is required for the @L positioning of the condition sensor 7.8. Since the processing in the processing circuit 9 is generally performed using high-precision analog signals, there is a problem in that the analog devices forming the processing circuit 9 become expensive.

In this way, direct teaching type heavy-duty robots have the advantage of being extremely easy to teach, but on the other hand, the structure of the robot body is complicated. Arm position control during operation is also complicated and the price is high.

This invention was made in view of the above-mentioned circumstances, and is a direct teaching type that can perform direct teaching using a weak force without providing a clutch, and can also control the arm position during driving with a simple configuration. One of our objectives is to provide industrial robots.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention
A first position detector that detects the amount of movement of the drive source at a stage upstream of the transmission mechanism, and a movement of the arm! Detecting the lI amount at a later stage of the transmission mechanism; a linen 2 position detector;
If the arm is not energized during teaching, the drive source is controlled so that the deviation of the detection values of the first and second position detectors caused by this energization is zero. The department and the tfNI.

[Effect]

By means of the above-mentioned means, the arm can be operated with a weak force without providing a clutch mechanism during teaching, and
As a result, arm position control can be performed stably during operation without providing a compensation circuit.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

11 is a block diagram showing the configuration of an embodiment of the present invention, and parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the figure, 15 and 16 are position detectors such as pulse encoders (two-phase pulse encoders), and position detector 1
A position detector 16 is provided between the motor 3 and the reducer 5 to detect the amount of drive of the motor 3 (rotation amount of the motor shaft).
is provided between the reducer 5 and the arm 1 to detect the amount of movement of the arm 1.

In this case, the position detectors 15 and 16 are both capable of detecting the rotational direction of the axis to be detected.

SWl is a switch that switches and supplies the output pulse of the position detector 15 to either the control device 10 or the deviation detection circuit 18. During operation (playback), the output terminal a is
side, and touches the output end side during teaching. Deviation detection circuit 18
is the position detector 15 supplied via the switch SW1.
The detection amount and rotation direction are measured from the output pulses of the position detector 16 and the output pulses of the position detector 16, and the deviation of the first measurement shift is detected, and this deviation signal is converted into an analog signal and supplied to the amplifier 19. . The analog signal in this case is set to be positive when the output shaft of the reducer 5 is twisted clockwise with respect to the input shaft, and negative when the reverse is the case. The amplifier 19 amplifies the analog deviation signal and then supplies it to the summing point 20 via the switch SW2. The switch SW2 is a switch that is turned on when teaching off percentage during operation.

Further, a speed command signal is supplied from the control device 10 to the addition point 209. When the addition result at the addition point 2o is positive, the motor 3 rotates clockwise, and when it is negative, the motor 3 rotates counterclockwise. do.

Next, the operation of this embodiment will be explained.

First, the operation during teaching will be explained. In this case, the speed command signal supplied from the control device 10 to the addition point 20 is zero, and as a result, the motor 3 does not rotate. and,
When the operator biases the arm 1 clockwise, the transmission shaft rotates slightly on the output side of the reducer 5 due to the elasticity of the reducer 5 due to the operator's biasing force, but the motor 3 stops as described above. Therefore, the shaft on the input side of the reducer 5 is in a stopped state. As a result, the position detector 16 outputs a pulse signal corresponding to the rotation amount and rotation direction, but the position detector 15 does not output a pulse signal.

Then, the deviation detection circuit 18 detects a deviation in the amount of movement (e!, corresponding to the amount of torsion between the input side and the output side of the speed M5) from the output signal of the position detector 15°16, and outputs an analog signal corresponding to this deviation. is supplied to the amplifier 19. The analog signal output in this case is positive because the shaft on the output side of the reducer 5 is twisted clockwise. Then, a positive analog signal corresponding to the twist amount is output from the amplifier 19, and as a result, the addition result at the addition point 20 becomes a positive value corresponding to the twist amount, and the motor 3 rotates clockwise. On the other hand, when the operator biases the arm 1 counterclockwise, the output shaft of the reducer 5 twists counterclockwise, so the deviation detection circuit 18 outputs a negative analog signal, contrary to the above case. Output. Therefore, the addition result at the addition point 20 is negative, and the motor 3 rotates counterclockwise.

In this manner, during teaching, the motor 3 rotates following the force applied by the operator, so that the considerably heavy arm can be moved in any direction with a small force from the operator. The position data of the arm 1 thus moved is sequentially supplied from the position detector 16 to the control device 10.

Next, to explain the operation during operation, in this case, the switch SW2 is turned off, so the speed command signal of the control device 10 is directly supplied to the amplifier 111/c via the addition point 20, and the motor 3 receives the speed command signal. Rotates at a speed based on On the other hand, since the switch SW 1 is on the output terminal a side, the output signal of the position detector 15 is supplied to the control device 10, and the control device 10 controls the position of the arm 1 based on the output signal of the position detector 15. In this case, the position detector 15 that outputs a position signal during operation is not affected by backlash or lack of rigidity of the reducer 50, so the control device 10 can stably arm the arm based on the output signal of the position detector 15. Position control can be performed. Therefore, no compensation circuit or the like is required at all.

It should be noted that the amount of force applied by the operator to move the arm 1 during teaching can be arbitrarily set by changing the gain of the amplifier 19.

In addition, when the arm 1 is affected by an external force qI such as gravity, for example, using a spring balance mechanism, the input side and the output side of the reducer 5 can be adjusted in a state where the operator is not operating the arm 1. It is only necessary to prevent twisting from occurring.

〔Effect of the invention〕

As explained above, the present invention includes a first position detector that detects the drive amount of the drive source at a stage upstream of the transmission mechanism, and a position detector that detects the movement amount of the arm at a stage downstream of the transmission mechanism. If the second position detector and the arm are biased during teaching, the driving is performed so that the deviation between the detected values of the first and second position detectors caused by this bias is O. Since it is equipped with a control section that controls the source,
During teaching, the robot arm can be moved by a weak force without using a clutch mechanism, and during operation, the position of the arm can be stably controlled without using a compensation circuit. Therefore, the mechanical structure can be simplified, and an expensive compensation circuit is not required, so that the price can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a block diagram showing the structure of a conventional direct instructor industrial rosette. 2...Position detector (second position detector), 1G
......Control device (control unit), 15...Position detector (first position detector), 1B...Deviation detection circuit% 19...... Amplifier, 20...
・Additional points (18 to 20 above are the control section) %sw i , S
W2...Switch (control unit).

Claims (1)

[Claims] In a direct teaching type industrial robot that operates by transmitting the driving force of a drive source to an arm via a transmission mechanism such as a speed reducer, a first position where the amount of movement of the drive source is detected at a stage upstream of the transmission mechanism. a detector; a second position detector that detects the amount of movement of the arm at a subsequent stage of the transmission mechanism; when the arm is energized during teaching;
A direct teaching type industrial robot characterized by comprising: a control section that controls the drive source so that a deviation between detected values of the first and second position detectors caused by this urging becomes zero. .