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Description  |
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TECHNICAL FIELD
The present invention relates to an industrial robot control apparatus for
controlling paint robots and the like, and more particularly, to an
industrial robot control apparatus able to carry out a safe, accurate
teaching of a robot.
BACKGROUND ART
To operate a paint robot or the like, the operator holds a paint gun,
teaches the required movements of the gun to the robot, and causes the
robot to store the taught movements and to carry out the painting process
in accordance with those stored movements. During the teaching operation,
vectors of force are detected by a force sensor attached to the distal end
of a robot arm, and are decoded by a control apparatus, which then causes
the robot to act in the directions of the vectors.
In this system, however, since the robot is controlled by the control
apparatus, an incorrect operation by the operator or a malfunction of the
robot control apparatus may place the operator in danger, despite the low
speed of the operation.
Further, since the robot is operated in the directions of the vectors of
force detected as described above, the reactions of the robot during the
operation are very slow, and thus a delicate positioning movement and
accurate teaching are difficult.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide an industrial robot
control apparatus which solves these problems, and is able to carry out a
safe, accurate teaching of a robot.
To solve the aforementioned problems, according to the present invention,
there is provided an industrial robot control apparatus for teaching an
industrial robot and operating the robot in accordance with the teaching,
which comprises
a teaching handle having a teaching switch and a brake release switch,
a sequence control circuit able to bring a servo amplifier to an emergency
stop condition, to thereby release a dynamic brake of a servomotor and
release a brake, in response to a signal from the brake release switch,
and
a teaching memory means for storing taught positions through the operation
of the teaching switch.
According to the present invention, to begin a teaching operation, first
the operator grips the teaching handle, whereby the brake release switch
is activated and the servo amplifier is brought to an emergency stop
condition in response to a signal from the switch, so that an output from
the servo amplifier to the servomotor is cut off, and thus the servomotor
is in a dynamically braked state.
Namely, the sequence control circuit releases the dynamic brake, and also
releases the brake.
Accordingly, the operator is able to operate the robot as desired and teach
required movements to the robot, and the robot stores the taught positions
through operation of the teaching switch.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an industrial robot control apparatus
according to one embodiment of the present invention; and
FIG. 2 is a diagram showing details of a teaching handle.
BEST MODE OF CARRYING OUT THE INVENTION
One embodiment of the present invention will now be described with
reference to the drawings.
FIG. 1 shows a block diagram of an industrial robot control apparatus
according to one embodiment of the present invention. In FIG. 1, numeral 1
denotes a sequence control circuit for controlling output to a servomotor
and the like; 2 denotes an auxiliary brake control circuit which supplies
power to a brake, described later; 3 denotes a relay for disconnecting a
dynamic brake of the servomotor; 4 denotes a relay for switching the brake
control to an automatic or manual mode; 5 denotes an amplifier power
circuit which supplies power to a servo amplifier 6; 7 denotes a main
brake control circuit for controlling the brake; and 8 denotes an
intrinsically safe circuit, which lowers the voltage, current, etc., of
signal lines below the level at which arcing will occur, to prevent
explosions caused by an ignition of an evaporated solvent in a paint robot
or the like, caused by sparking at electrical contacts therein.
Numeral 9 denotes a teaching handle provided with a teaching switch 10 and
a brake release switch 11. When teaching required movements to the robot,
the teaching switch 10 is operated at a certain point and the robot
control apparatus then stores this point. To carry out the teaching
operation, the operator grips the teaching handle 9 to activate the brake
release switch 11 and release the brake described later. The teaching
handle 9, the teaching switch 10, and the brake release switch 11 will be
described in detail later.
Numeral 12 denotes a servomotor for driving the robot. Although about three
to six servomotors are actually used, only one is shown and the others are
omitted for simplicity. Numeral 13 denotes a brake, which is used to brake
the shaft of the servomotor or a robot-side rotating shaft. As in the case
of the servomotors 12, although each servomotor 12 is provided with a
brake 13, only one of the brakes 13 is shown and the others are omitted
for simplicity. The brake 13 is released when an electric current is
supplied thereto, and operated when the electric current supply is cut
off.
FIG. 2 shows details of the teaching handle. In FIG. 2, numeral 9 denotes
the teaching handle, which is fixed to a torch 15, and 10 denotes the
teaching switch. During the teaching process, the operator depresses the
teaching switch 10 at a certain point and this taught point is stored in
the robot control apparatus. Numeral 11 denotes the brake release switch
11. To start the teaching process, the operator grips the teaching handle
9 and the brake release switch 11 is then activated by the pressure of the
operator's grip. Numeral 16 denotes a paint discharge port.
Namely, when the operator grips the teaching handle 9 to start the teaching
process, the brake release switch 11 is activated to bring the servo
amplifier 6 to an emergency stop condition, and thus the teaching process
can be carried out safely and easily.
The control of the sequence control circuit 1 when carrying out the
teaching process will be described with reference to FIG. 1. When the
operator grips the teaching handle 9 to start the teaching process, the
brake release switch 11 is activated and a signal is output to the
sequence control circuit 1, which then sends an emergency stop signal to
the amplifier power circuit 5. The amplifier power circuit 5 then stops
the supply of power to the servo amplifier 6, and thus a control current
supplied by the servo amplifier 6 to the servomotor 12 is cut off.
When the amplifier power circuit 5 is brought to an emergency stop
condition, the servo amplifier 6 brings the servomotor 12 to a dynamically
braked state. This is achieved by short-circuiting the windings of the
servomotor 12, by a resistor inside the servo amplifier 6. At this time,
however, since an arm of the robot is in a dynamically braked state, a
large resistance is imposed during operation of the robot arm. To remedy
this situation, the sequence control circuit 1 turns off the relay 3, to
thereby release the dynamic braking of the servomotor 12.
At this point, since the main brake control circuit 7 is in an emergency
stop condition, the current flow to the brake 13 is cut off to release the
brake. At this time, the arm of the robot cannot be moved, and thus the
relay 4 is switched to allow manual control and is connected to the
auxiliary brake control circuit, whereby current is supplied from the
auxiliary brake control circuit to release the brake.
In this state, the current flow to the servomotor is cut off, and thus the
arm of the robot cannot move and endanger the operator. Further, since the
dynamic brake and the brake are released, the operator can safely and
accurately carry out the teaching process by depressing the teaching
switch 10 at each teaching point, whereby the taught point is memorized by
the robot control apparatus.
According to the present invention, as described above, the control
apparatus side is brought to an emergency stop condition by activating the
brake release switch of the teaching handle, to thereby cut off the output
to the servomotor and release the dynamic brake and the brake, and thus
the teaching process can be carried out safely and accurately.
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