JPS5947329B2 - Playback robot teaching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a teaching device for a playback type robot that operates according to the contents taught, and more specifically, its purpose is to protect human safety from erroneous operation of the robot.

Position teaching in conventional PTP playback type industrial robots involves holding a small teaching device in one hand, which is equipped with a number of push button switches for forward and reverse driving to operate each axis, while pressing the push button switches with the other hand. Most methods teach the position by operating each axis and visually guiding a robot finger or tool to a teaching target point.

The human movement in this teaching method is to visually measure the difference between the current position and the taught target point, and then judge which axis and how much the robot should move to guide the robot to the taught target point. Then, select the corresponding pushbutton switch on the teaching device, guide the robot to the teaching target point while holding it down, visually determine whether the robot is being guided correctly, and make corrections if necessary. Become.
Moreover, during such trial and error, the corresponding switch must be selected from among the many pushbutton switches on the teaching device, which is also a very difficult task. Therefore, in order to teach a large number of positions, such complicated teaching operations must be repeated, resulting in a drawback that the teaching time is extremely long. In addition, when teaching the position of some CP playback type industrial robots, there is a method in which a human holds the tip of the robot's arm and manually moves the arm to the target point.
In this case, guidance is easy, but the drive source must be separated so that the robot's arm can move freely and lightly under human power, which requires a separate mechanism, making the robot large and expensive. Also, since the direction of the force is opposite between the bending of the arm when the arm is moved by a driving source and the bending of the arm when the arm is moved by human power, there is an error in the position during teaching and playback. There were drawbacks such as the occurrence of Therefore, the present inventor developed a new teaching method for the purpose of solving such problems.

Fig. 1 shows a five-axis articulated robot using the teaching method previously developed by the present inventor, in which the torso 2 rotates with respect to the legs 1, and the upper arms 3 and lower arms 4 rotate. , the wrist 5 is rotatable and pivotable, and when teaching, a person grasps the teaching arm 6 and moves the teaching arm 6 in the direction of the teaching target position.
The detector in the teaching arm 6 drives a drive source (the same one that moves during playback) necessary to move to the teaching target position, and the robot moves toward the teaching target position.

That is, this is a method in which a human moves the teaching arm 6 to guide the robot to a teaching target position and teaches the position and speed. However, in such a method, the human holds the teaching arm 6 during teaching, that is, is in the vicinity of the robot's arm, so if the robot malfunctions and goes out of control,
There is a risk of harm to humans.

This is not limited to this teaching method, but even with the conventional teaching method using a push button switch for inching, the robot can be guided from a distance to the vicinity of the teaching target point, but if the robot is only a few millimeters away from the target point. Once that point is reached, it is still necessary for a human to look into the target point and visually check for errors, which is equally dangerous.

The present invention was developed to solve such problems, and in the teaching device according to the present invention, the driving force of the drive source during teaching is made smaller than during reproducing.

That is, as shown in Figure 2, the force is F during playback,
At the time of teaching, the drooping characteristic (dotted chain line or dotted line) is set to t, which is smaller than F, in order to reduce harm to humans in the event of runaway. Hereinafter, a specific configuration of the present invention will be explained using the drawings of FIGS. 3 and 4, taking as an example a case where a DC electric servo is used as a drive source. Note that a similar device can be configured for other servos such as hydraulic pressure. Furthermore, in an electric servo, the speed, ie, the number of rotations of the motor, is related to the armature voltage of the motor, and the force, ie, torque, is related to the armature current of the motor. FIG. 3 shows a circuit according to an embodiment of the present invention using a drooping resistor R. In FIG. 3, S1 is a switch that closes during teaching, S2 is a switch that is linked to this switch and closes during playback, and R is a drooping resistor. The resistance, M is the motor.

That is, with the circuit shown in FIG. 3, the output characteristic during teaching becomes as shown by the dotted line in FIG. 2, and no large current flows through the motor M during teaching.

FIG. 4 shows a circuit according to another embodiment of the invention,
In FIG. 4, SCR is a thyristor and SH is a shunt. The shunt SH detects the current flowing through the motor M, and the thyristor SCR is controlled by the ignition control circuit 7 of the thyristor SCR based on this detected current. This prevents the value from exceeding a certain value. Also, during teaching, the switch S1 and the current limit value switching relay CRl of the ignition control circuit 7 are closed, and the current exceeding t in FIG. 2 is applied to the motor M.
The thyristor SCR is controlled so that the current does not flow. F is a fuse for overcurrent protection in case the ignition control circuit 7 does not operate normally. Further, in the circuit shown in FIG. 4, during regeneration, switch S2 is closed, current limit value switching relay CR2 is closed regardless of fuse F, and the rated current F flows through motor M.

That is, with the circuit shown in FIG. 4, the output characteristic during teaching becomes as shown by the dashed line in FIG. 2, the force during teaching is limited, and there is less damage in the event of runaway.

Combining such a teaching device according to the present invention with a teaching method previously developed by the present inventor will make it even more effective.

That is, in the teaching method described above, it is possible for a person to move each arm etc. with human power via the teaching arm 6 during teaching, and the drive source operated by the detector in the teaching arm 6 is a small Even if the motor torque is small due to the current limit value, as long as the force is small enough to cancel out the mechanical friction in the transmission system, the robot can be guided to the teaching target position by human power. Even if a robot's control device malfunctions and goes out of control, most of the force in the drive source will be absorbed by the gears of the mechanical transmission system, and the force in the arm itself will be weak, so there will be little harm to humans. Furthermore, during regeneration, the current limit value becomes a large value and the drive source generates a large force equal to the motor's rated strength, so there is no effect on the operation of the robot. Here, although Fig. 2 shows the drooping characteristic by a straight line, the point is that when displaying, the value t is smaller than F during playback.
The force at the time of teaching may be limited by a certain function of the speed.

By doing this, the person holding the teaching arm will not be pulled by the robot during teaching, and the limit value will be too small, making it difficult to guide the robot via the teaching arm. It is possible to create a robot that has arms that can freely move in the direction of the force applied by humans, and that is safe even in the event of a runaway operation. As described above, robots have problems such as safety in the event of malfunction, but the teaching device according to the present invention is extremely superior in that it can sufficiently ensure safety in the event of malfunction.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a five-axis articulated robot using the teaching method previously developed by the present inventor, and Fig. 2 shows characteristics for explaining the principle of the playback type robot teaching device according to the present invention. 3 and 4 are circuit diagrams showing the circuit configuration of a teaching device for a playback type robot according to an embodiment of the present invention. SL, S2...Switch, M...Motor, R...Drooping resistance, SCR...Thyristor, SH...Shunt, 1. ...Ignition control circuit.

Claims (1)

[Claims] 1. A teaching device for a playback type robot, characterized in that the maximum rated value of the force of a driving source during teaching is limited to a value smaller than the maximum rated value during playback.