JPH0661709B2 - Direct teaching type industrial robot teaching device - Google Patents

Description

The present invention relates to a teaching device for a direct teaching type industrial robot.

<Prior Art> The direct teaching method is a method of teaching the operating position by the operator directly grasping and moving the tip of the operating arm and the wrist of the robot. Because there is an advantage that you can teach efficiently,
It is applied to many robots, especially most of painting robots. However, if the operating force is heavy, not only is it difficult to operate and the advantages described above cannot be utilized, but it may also cause a physical disorder such as low back pain to the operator.
Therefore, various methods for reducing the teaching operation force have been proposed. The first method is to reduce the operating force by using a balancer to cancel the load moment generated by the load of the operating arm of the robot by the balance force moment generated by the force generated by the balancer.

The second method eliminates the rotational resistance of the drive equipment such as the drive motor and the rotational resistance and transmission efficiency of the power transmission equipment such as the speed reducer, that is, the resistance to the movement of the operating arm. The clutch mechanism is placed on the section to disengage the clutch mechanism during teaching operation to reduce the operating force.

Here, the operating force during direct teaching is
(A) Rotational resistance of drive equipment such as drive motors, rotational resistance and transmission efficiency of power transmission equipment such as (b) reduction gears, frictional resistance of c bearings, (d) difference in load moment due to operating arm weight and balance force moment due to balancer It is determined by the operation resistance consisting of four types of drive system resistances of unbalanced load.

<Problems to be Solved by the Invention> With respect to the above operating force, the rotational resistance and the transmission efficiency of the rotational resistance B of b can be eliminated by disconnecting the clutch mechanism according to the second method. However, this clutch mechanism needs to be provided for the number of operating axes of the robot, and since it operates only during direct teaching, the clutch operating switch has an interface for other operating modes (for example, regenerating operation, remote teaching, etc.). Requires a lock, the robot structure is complicated,
It has the drawback of being expensive.

Further, regarding the frictional resistance of the operating force c, that is,
The frictional resistance of the bearing portion in the power transmission mechanism can be eliminated by the clutch mechanism, but the bearing portion of the operating shaft itself cannot be eliminated.

Further, regarding the operating force D, a spring balance mechanism as shown in 102 of FIG. 3 is devised, and consideration is given so as to cope with the change of the load moment depending on the operation angle of the operation axis. The load moment applied to the portion 103 is the upper arm 10 that is rotationally coupled to the tip of the lower arm 103.
4, the lower arm portion 103, the upper arm portion 104, and the wrist portion 105 operate independently of each other by the wrist shaft 105 attached to the distal end portion thereof and the load (not shown) further ahead thereof, so that the graph shown in FIG. Even when the lower arm is fixed at a certain angle, there is a width shown by the solid line in the graph.

Also, the balance force moment is in the state shown by the broken line in the graph, and it is difficult to reduce the biased amount of the load moment and the balance force moment to zero.

As described above, in the conventional direct teaching robot, there is a problem that the advantage that the teaching force of the direct teaching is extremely easy because the operation force is not so light despite the complicated and expensive structure.

Therefore, an object of the present invention is to provide a teaching device for a direct teaching type industrial robot, which is extremely easy to teach direct teaching without having a complicated and expensive structure in view of the above-mentioned drawbacks.

<Means for Solving Problems> The present invention that achieves the above-mentioned object is to provide a driving current to the driving servo motor by bypassing the servo amplifier of a driving circuit including a power supply, a servo amplifier, and a driving servo motor. A bypass circuit having a current control circuit for limiting to a minute current that produces an output corresponding to an operating resistance for the drive servomotor, and a direction switching circuit for switching the current direction by the current control circuit. And a minute value of the current control circuit to a current value of a magnitude that generates an output corresponding to an operation resistance corresponding to the angle of the operating arm by a signal from a position detector connected to the operating arm drive mechanism including the servo motor. An operation to detect the teaching operation direction from the feedback circuit that changes the current and the signal from the position detector to control the direction switching circuit. And a direction detection circuit.

<Example> Here, an example of the present invention will be described with reference to the drawings. First
In the figure, a drive servomotor 3 for operating the operating arm 1 is fed to the operating arm 1 via a speed reducer 2. A position detector 8 that detects the operating position of the operating arm 1 is connected between the servo motor 3 and the speed reducer 2.

On the other hand, the power supply 7 is connected to the drive servomotor 3 via the servo amplifier 4 and a switch 15 described later. A bypass circuit for the servo amplifier 4 includes a current control circuit 12, a direction switching circuit 10, and a switch 15. Of these, the current control circuit 12 limits the current to a level at which the drive servomotor 3 does not start rotating, that is, a minute current corresponding to the operating resistance made of Iroha in the above description. Further, the direction switching circuit 10 is a circuit for switching the direction of this minute current, and is 2 when teaching.
The smooth operation is performed by switching the direction of the minute current to the operating direction of.

The position detector 8 has a circuit for feeding back a motion position of the motion arm 1 to the robot control circuit 5 and also a circuit for feeding back a signal to the motion angle detection circuit 14. The driving servomotor detected by the motion angle detection circuit 14 3, that is, based on the operating angle of the operating arm 1, the current value setting circuit 13 connected thereto determines the magnitude of the driving current corresponding to the unbalanced load of D in the conventional description, and the current control circuit 1
2 is commanded to this current value to change a minute current to control it as a driving current. The signal from the position detector 8 is also fed back to the movement direction detection circuit 11 to determine the movement direction of the movement arm 1. The direction switching circuit 10 connected to this is instructed to switch the current direction. Reference numeral 6 is a mode changeover switch for selecting the direct teaching mode or the robot drive mode, and is for switching the switch 15.

In the above configuration, the switch 15 is in the state of a solid line by the direct teaching mode selection of the mode changeover switch 6, and the current from the power supply 7 is limited by the current control circuit 12 to only a very small current at which the motor does not start rotating. It is supplied to the motor 3 and counteracts the load of the operating arm 1 to balance the operating arm 1. Next, when the operator moves the operation arm 1, the operation angle detection circuit 14 and the current value setting circuit 13 are generated by the signal from the position detector 8 connected to the drive mechanism.
The current control circuit 12 is controlled to a current value for obtaining a motor output that opposes the load moment generated by the operation angle of the operation arm 1 at that time.

Further, when the operator moves the operation arm 1, the position detector 8 connected to the drive mechanism is displaced, and the movement direction detection circuit 11 determines the direction of the current to the servo motor 3 according to the displacement amount. The switching circuit 10 operates to switch the direction of current.

Therefore, first, a minute current corresponding to the operation resistance flows, and the signal of the position detector 8 is displaced according to the movement of the operating arm 1, so that the current that always generates the balance force according to the operating angle of the operating arm 1 is the servo. The current direction is switched in the direction in which the current is supplied to the motor 3 and is applied to the operating arm 1, and it is possible to operate with a light external force, that is, an operating force.

FIG. 2 is a block diagram showing a second embodiment of the present invention. Only differences from the block diagram shown in FIG. 1 will be described.
The operating arm 1 is provided with an operation switch 20 operated by an operator,
A switch 21 for turning on / off the circuit of the current supplied to the servomotor 3 by the signal of the switch 20 is provided.

As a result, electric current is supplied to the servomotor 3 according to the operator's intention, so that the operator's safety can be improved. Further, if the operation switch 20 is turned off when the operator releases it, the safety can be further enhanced.

<Effects of the Invention> (1) By supplying the driving servo motor with a minute current that generates an output that balances the load of the operating arm operated by the motor, the operating resistance is offset, and a very light external force is applied. To obtain a direct teaching robot that can be operated simply by giving a motion arm.

(2) The minute current is limited by the current control circuit, so the risk of runaway can be eliminated.

(3) Since the circuit from the servo amplifier is shut off in conjunction with the switch that switches the operation mode, there is no danger of runaway.

(4) The operation resistance due to the unbalanced load can be eliminated by further adding the current that always generates the balance force according to the operation of the operation arm.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a modification, FIG. 3 is a side view showing a spring balancer of an articulated robot, and FIG. 4 is a load and balance force by the spring balancer. It is a graph which shows. In the drawings, 10 is a direction switching circuit, 11 is an operation direction detection circuit, 12 is a current control circuit, 13 is a current value setting circuit, and 14 is an operation angle detection circuit.

Claims (1)

[Claims] 1. A bypass circuit for bypassing the servo amplifier of a drive circuit comprising a power supply, a servo amplifier and a drive servo motor to supply a drive current to the drive servo motor, the bypass circuit for the drive servo motor. It has a bypass circuit having a current control circuit that limits a minute current that generates an output corresponding to an operation resistance and a direction switching circuit that switches the current direction by this current control circuit, and is connected to an operating arm drive mechanism including the servo motor. With the signal of the position detector and the signal of the position detector and the feedback circuit that changes the minute current of the current control circuit to a current value of a magnitude that generates an output corresponding to the operation resistance according to the angle of the operating arm Direct teaching further including an operation direction detection circuit for detecting the teaching operation direction and controlling the direction switching circuit Teaching device of the industrial robot.