Power plants – Pressure fluid source and motor
Patent
1984-08-03
1986-09-30
Chambers, A. Michael
Power plants
Pressure fluid source and motor
414 7, 901 28, 901 29, B65J 1702
Patent
active
046140840
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a mobile link or coupling between a supported and supporting element. Such a device allows imparting displacements in several degrees of freedom to the supported element with respect to the supporting one.
In the present state of the art, robotics makes use of different types of manipulator arms (hydraulic, pneumatic, electric), that constitute the support element, the supported element being a tool, as a rule being a gripping tool. The force that the arm can exert is rather incompatible with its operational speed and especially with accuracy of displacement: The band or cable operated manipulator arms evince good accuracy but their force is limited, whereas the hydraulically actuated arms are powerful but often lacking in accuracy. This problem has been partly resolved by providing the manipulator arm with a flexible coupler means, for instance a Nevins wrist, which can deform under stress of which it indicates both the magnitude and the direction. It is also necessary that the arm be capable of low amplitude displacements performed with high accuracy in order to assemble as desired. Again it has been suggested to build arms with wrists performing high accuracy displacements of low amplitudes, but such require a large number of motors equipped with heavy and bulky reducer means which correspondingly decrease the arm's power.
Elsewhere the European patent No. 017016 and the U.S. Pat. No. 3,284,264 disclose "elephant trunk" devices which can be powered hydraulically; these devices however incur the drawback of requiring external pressurizing systems such as compressors or the like, with the position of the various elements of said devices depending on an external pressure of which the accurate control will always demand great care.
The main object of the present invention is to palliate the drawbacks of the known devices by creating a mobile link or coupling making possible powerful displacements with good accuracy.
Another object of the present invention is to create a link or coupling with a lesser weight than those of the prior art.
Another object of the present invention is to create a link or coupling permitting displacements of fine enough a resolution to be mounted on any manipulator arm (and hence of low cost).
Another object is to create a link or coupling allowing displacements of sufficient amplitude of the supported element with respect to the supporting element, with operational speed and accuracy higher than for the manipulator arms of the prior art.
The mobile link or coupling object of the invention includes:
a bearing framework designed to be fixed on the supporting element (manipulator arm),
a mobile framework designed to permit fastening the supported element (last member),
a plurality of flexible jack means each with a deforming wall extending about a so-called longitudinal axis, and rigid fastening walls located at each end of said deforming wall, said flexible jack means being arranged between the bearing framework and the mobile framework so as to keep said mobile framework in a relative position to said bearing framework depending on the deformation states of said flexible jack means;
and remote control means for the flexible jack means.
In one feature of the present invention, the remote control means include a variable-capacity tank which is associated with and connected to each of said flexible jack means with which it forms a closed fluid circuit, said control means being designed to determine in the set of variable-capacity tanks such capacities as would generate a set of deforming states in the flexible jack means in order to achieve this desired position of the mobile framework.
In view of its design, such a device therefore allows accurately positioning the supported element when starting from an approximate end position of the supporting element by means of displacements generated by actuating flexible jack means. The jack means are operated by varying the capacities of each of the tanks associated with the jacks. It is essential to bear in mind that t
REFERENCES:
patent: 2780065 (1957-02-01), Sponnhake
patent: 2927432 (1960-03-01), Povoy
patent: 3284964 (1964-03-01), Saito
patent: 3583752 (1971-06-01), Hugo
patent: 4369814 (1983-01-01), Humphrey
Clot Jean
Falipou Jean
Centre National de la Recherche Scientifique (C.N.R.S.)
Chambers A. Michael
Dutton, Jr. Harold H.
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