Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1986-10-06
1989-03-28
Ro, Bentsu
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318480, 901 47, B25J 1906
Patent
active
048167282
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a robot control apparatus and, more particularly, to a robot control apparatus having a novel limiter structure for limiting the operating range of each axis constituting a movable portion of a robot mechanism.
An industrial robot grasps a workpiece by means of a hand, or subjects a workpiece to machining, e.g., welding by a tool such as a torch, mounted at a distal end of an arm. In a robot of this type, ordinarily an operating command is issued by a numerical control (NC) unit installed remotely from the robot mechanism, and servomotor power is delivered to the robot mechanism via a magnetics panel, or the like, so that the arm is operated by the servomotor.
Besides a power system cable, a signal system cable is also provided between the robot mechanism and the control unit for transferring such signals as a brake drive signal, signals from various sensors provided on the hand, and signals from limiter switches for limiting the operating range of each axis constituting the robot arm.
In a conventional industrial robot of the above kind, electric signals are used not only for the servomotor power but also for the limiter switch signals of the respective axes; the limiter switches protect the robot. Since the cables usually are arranged close together, an electrical noise component contained in the servomotor power mixes with the limiter switch signals, as a result of which the robot malfunctions. This effect becomes quite pronounced because the power and signal cables are intermingled and packed closely together particularly within the robot arm.
Furthermore, since the limiter switches employ contact switches, the contacts sustain wear and eventually fail to provide smooth on/off action with prolonged switch use. In addition, owing to wear of an operating member, accidents occur in which the limiter switch does not operate even when a dog is actuated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a highly reliable robot control apparatus which solves the aforementioned problems of the prior art.
According to the present invention, there is provided a robot control apparatus having a limiter structure for limiting an operating range of each axis constituting a movable portion of a robot mechanism, the robot control apparatus being installed at a position remote from the robot mechanism. The robot control apparatus has a photo-interrupter so adapted that, when a light-interrupting disk attached to one side of the movable portion of the robot mechanism arrives at a predetermined position, the light-interrupting disk interrupts a luminous flux passing through an optical path provided on another side of the movable portion. One optical fiber cable is provided for guiding the luminous flux to the photo-interrupter, and a second optical fiber is provided for transferring a limiter signal from the photo-interrupter.
Thus, according to the present invention, an optical fiber cable is employed as the limiter signal cable. As a result, an electrical noise component contained in the servomotor power does not mix in which the signals from the limiter switches and, hence, the robot does not malfunction and the limiter switch signal lines do not pick up foreign noise. In addition, use of the photo-interrupter provides a limiter switch which is contactless.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view illustrating an industrial robot which includes a robot control apparatus according to the present invention;
FIG. 2 is a block diagram illustrating an example of a light-emitting section;
FIG. 3 is a block diagram illustrating an example of a light-receiving section;
FIG. 4 is a block diagram of an optical signal system illustating an example of a limiter switch mechanism; and
FIG. 5 is a perspective view illustrating the arrangement of a photo-interrupter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will now be described in detail with reference to the drawings.
In FIG. 1
REFERENCES:
patent: 3888362 (1975-06-01), Fletcher et al.
patent: 4295740 (1981-10-01), Sturges
patent: 4420253 (1983-12-01), Pryor
patent: 4453085 (1984-06-01), Pryor
patent: 4481592 (1984-11-01), Jacobs et al.
patent: 4501961 (1985-02-01), Stauffer
patent: 4570065 (1986-02-01), Pryor
patent: 4626999 (1986-12-01), Bannister
patent: 4633079 (1986-12-01), Rieger
Fanuc Ltd
Ro Bentsu
LandOfFree
Photoelectric motion limiting control apparatus for a robot mech does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photoelectric motion limiting control apparatus for a robot mech, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoelectric motion limiting control apparatus for a robot mech will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1661614