Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Patent
1984-12-24
1988-02-16
Paperner, Leslie J.
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
414735, 464117, 901 19, 901 29, B25J 1702
Patent
active
047247169
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates to a joint mechanism in which several joints are connected in series so as to get a soft resiliency. More particularly, it relates to a joint mechanism which may be flexed in any direction and in which a highly precise positioning of the distal end of the joint mechanism may be obtained; high durability, softness and rigidity can be obtained; and which is preferable for arms or wrists of robots or manipulators, etc.
2. Description of the Prior Art:
As one example of a soft joint mechanism, a robot arm described in Japanese Laid-Open Patent Application No. 57-66890 is already known. This robot arm is made such that, as shown in FIG. 1(a), the closed ring-shaped links A, B, C . . . are linked like a chain. The adjoining links are connected by rotary sliding joints J in which an axial sliding and a swivelling can be performed simultaneously. Alternate links are swivellingly connected to each other by ball joints BJ arranged on a central axis of the joints. A fixed machine table M and the proximal link A are swivellingly connected by a ball joint BJ.sub.1, and the second link B is also connected to the fixed machine table M with a ball joint BJ.sub.2.
In the case of the above-described robot arm, the proximal link A is oscillated (by means not shown) in respect to the machine table M in a horizontal plane containing the link A around the ball joint BJ.sub.1. This oscillation causes all the links to swivel in the swivelling direction. That is, each of the joints undergoes a swivelling movement, so that an entire smooth swivelling movement may be provided and a soft arm may also be attained.
However, in the case of the above-described robot arm, when the link A is swivelled in a vertical plane crossing at a right angle with a horizontal plane containing the above link A, for example, by an angle .alpha..sub.1 around the ball joint BJ.sub.1, as shown in FIG. 1(b), a member connecting the link A to the link B is fixed to the link A at a right angle thereto, so that, after the swivelling operation, the link B has an inclination angle of .alpha..sub.1 in respect to a vertical plane Y.sub.1.
In turn, in the case of the link B, the link B swivels only by an angle .alpha..sub.2 due to a swivelling operation of the above link A around the ball joint BJ.sub.2 (placed at the fixed position). It can easily be seen that .alpha..sub.1 .noteq..alpha..sub.2, due to the different rotational centers of the links A, B. Along with this movement, the member X.sub.1 is also inclined at an angle of .alpha..sub.2 in respect to the vertical plane Y.sub.1 (to X.sub.1 ').
In turn, the member X.sub.1 is fixed at a right angle to the link A as described above, so that the member X.sub.1 must be inclined by an angle of .alpha..sub.1 in respect to the vertical plane Y.sub.1 due to the swivelling operation of the link A. Accordingly, the angle .alpha..sub.2 in respect to the vertical plane Y.sub.1 can not be obtained. That is, the member X.sub.1 can not maintain a right angle in respect to the upper and lower sides B.sub.1 and B.sub.2 of the link B. Accordingly, the member X.sub.1 can be inclined only by an angle of (.alpha..sub.2 -.alpha..sub.1) in respect to the sides B.sub.3 and B.sub.4, which are perpendicular to the sides B.sub.1 and B.sub.2.
However, since the link B is naturally composed of highly rigid material, the distance between the sides B.sub.1 and B.sub.2 forming the link B is kept constant, and the length of the member X.sub.1 is also kept constant. Furthermore, the distance between the rotary sliding joints J, J at both ends of the member may not be varied, so the member X.sub.1 is kept at a right angle in respect to the sides B.sub.1 and B.sub.2, and the member X.sub.1 may not be inclined only by an angle of (.alpha..sub.2 -.alpha..sub.1) in respect to the sides B.sub.3 and B.sub.4.
Therefore, in the case of the robot arm as described above, the folding direction is limited in a horizontal plane containing the link A shown in FIG. 1(a). That is, t
REFERENCES:
patent: 4107948 (1978-08-01), Molavg
patent: 4300362 (1981-11-01), Lande et al.
patent: 4511305 (1985-04-01), Kawai
Kabushiki Kaisha Kobe Seiko Sho
Paperner Leslie J.
Underwood Donald W.
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