Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1996-03-29
1998-01-27
Ip, Paul
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
31856816, 3185682, 414730, 385 59, B25J 1900, B65B 2102
Patent
active
057125520
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a robot which does not require electric wires (power transmission wires and signal wires) for interconnecting joint shafts.
BACKGROUND ART
Conventional electrically operated robots, irrespective of whether the vertical multiple-joint type shown in FIG. 9(a) of the accompanying drawings or the horizontal multiple-joint type shown in FIG. 9(b) of the accompanying drawings, require electric wires extending between joints, such as electric wires 91 including electric power wires for energizing motors installed in the respective joints, electric power wires for detectors which detect angular displacements of the motors, and output wires for outputting detected signals. The electric wires used with robots have been problematic in that the length of the electric wires used poses limitations on the range of operation of the robot, and the electric wires are subject to metal fatigue owing to repetitive operation of the robot.
To solve the above problems, Japanese patent publication No. 5-13796 has proposed a device which employs slip rings to transmit electric power between the shafts through surface-to-surface contact for thereby allowing a robot arm to operate in an angular range of 360| or greater and also eliminating electric wires for such electric power transmission.
However, the slip rings are conducive to frictional damage and noise, and may possibly cause an insulation failure which tends to prevent the robot from operating stably if used in machine shops exposed to an oil mist and chips.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a no-wiring robot of the multiple-joint type which transmits electric power and signals between joints thereof in a contactless manner.
An electrodeless unit for transmitting electric power by way of high-frequency electromagnetic induction and a unit for transmitting signals by way of optical transmission or high-frequency electromagnetic induction are installed in either a reduction gear that is coupled to the shaft of a motor for actuating each of the shafts of a robot or a direct-drive motor. Electric power or signal wires are drawn through a groove or hollow defined in an output shaft of the reduction gear or the direct-drive motor. Information produced ahead of the output shaft is fed back over signal wires that are drawn through the groove or hollow defined in the output shaft.
With the above arrangement, a multiple-joint robot capable of rotation about multiple joints is free of mechanical stresses which would otherwise heretofore be posed on electric power and signal wires by movement of the joints, and also free of wire-dependent limitations on a range of joint movement because it does not suffers the crossing of the wires.
According to the present invention, therefore, there are no limitations on the range of movement, and it is possible to realize a multi-turn arm. Furthermore, the problem of an insulation failure which tends to be caused by an oil mist and chips with no-wiring rotatable shaft using slip rings that have heretofore been proposed, and also of noise can be solved for stable transmission of electric power and signals.
In addition, use of separable and connectable units for transmitting electric power and signals makes it possible to achieve a structure by which not only multi-turn about the shafts is possible, but also the shafts can be detached and replaced. Controllers for the shafts are reduced in size and positioned dispersely, and are interconnected by a network for communications and power and a mechanically rigid mechanism, resulting in a robot comprising arm units that can be controlled independently for respective shafts, self-controlled, and replaced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view showing a multiple-joint robot according to an embodiment of the present invention.
FIG. 2 is a sectional view showing electric power and information output lines through an output shaft of a reduction gear which is part of the embodi
REFERENCES:
patent: Re34597 (1994-05-01), Akeel
patent: 4676002 (1987-06-01), Slocum
patent: 4766322 (1988-08-01), Hashimoto
patent: 4808064 (1989-02-01), Bartholet
patent: 4816728 (1989-03-01), Kurakake
patent: 5049797 (1991-09-01), Phillips
patent: 5069524 (1991-12-01), Watanabe et al.
Hiraga Yoshiji
Hirai Junji
Ishibashi Ichiro
Kaku Yasuhiko
Ip Paul
Kabushiki Kaisha Yaskawa Denki
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