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 Title: |
US5179525:
Method and apparatus for controlling geometrically simple parallel mechanisms with distinctive connections
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Griffis, Michael W.; Gainesville, FL
Duffy, Joseph; Gainesville, FL
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| Assignee: |
University of Florida, Gainesville, FL
other patents from UNIVERSITY OF FLORIDA (678945) (approx. 657)
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| Published / Filed: |
1993-01-12
/ 1990-05-01
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| Application Number: |
US1990000517371
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| IPC Code: |
Advanced:
B23Q 1/54;
B25J 9/16;
B25J 17/02;
G09B 9/08;
G09B 9/14;
Core:
B23Q 1/25;
G09B 9/02;
more...
IPC-7:
G06F 15/20;
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| U.S. Class: |
Current:
703/001;
434/055;
Original:
364/512;
364/578;
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| Field of Search: |
364/578,167.01,512
248/371,163.1,637,651,396,550
434/058,55
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| Priority Number: |
| 1990-05-01 |
US1990000517371 |
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| Abstract: |
A system, method and apparatus for controlling, via a closed-form forward displacement computation, the position and orientation of a movable platform of a parallel mechanism. A movable platform is supported above a base platform by a plurality of parallel support legs such as linear actuators. The dimensions of the base platform and the movable platform, as well the lengths of the support legs, are provided to a control system. The control system is operative to compute at least one closed-form forward displacement solution of the geometry of a polyhedron (an octahedron for the disclosed embodiments) formed by the movable platform, the base platform, and the support legs. The control system determines a final position and orientation of the movable platform by eliminating imaginary roots of the closed-form solutions and roots which would result in discontinuous paths of travel for the movable platform. A novel special 6-6 parallel mechanism is also disclosed. The control system is suitable for controlling known 3-3 or 6-3 Stewart platforms in a novel manner, as well as controlling the novel special 6-6 parallel mechanism. The special 6-6 parallel mechanism is distinguished from a general 6-6 by the fact that it is geometrically reducible to an octahedron, and therefore it has a simple geometry, even though its legs possess distinct connections. Also disclosed is a method for reducing the novel special 6-6 parallel mechanism to a Stewart platform equivalent, which is then controlled by the disclosed closed-form forward displacement control system.
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| Attorney, Agent or Firm: |
Spensley, Horn, Jubas & Lubitz ;
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| Primary / Asst. Examiners: |
Lall, Parshotam S.; Ramirez, Ellis B.
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| Maintenance Status: |
E2 Expired Check current status
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| INPADOC Legal Status: |
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Family Legal Status Report
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| Designated Country: |
CA EP JP KR
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| Family: |
Show 6 known family members
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First Claim:
Show all 60 claims |
What is claimed is:
1. A motion system capable of motion in six degrees of freedom, comprising:
- a base platform providing at least three points of connection in a first plane;
- a movable platform providing at least three points of connection in a second plane;
- at least six linearly extensible support members extending from said points of connection in said base platform to said points of connection on said movable platform;
- coupling means for providing said linearly extensible support members with at least two rotation degrees of freedom at said points of connection; and
- closed-form forward displacement control means, coupled to said linearly extensible support members, (1) for determining, in response to selective changes in the lengths of said linearly extensible members, at least one closed-form forward displacement solution of the geometry of a structure formed by said movable platform, said base platform, and said linearly extensible support members, such structure being reducible to an equivalent octahedron, and (2) for providing control signals in response to said solutions, said control signals being used to produce predictable motion of said movable platform.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 34 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other Abstract Info: |
DERABS G91-353990
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| Other References: |
Stewart, "A Platform with Six Degrees of Freedom", Proc. Inst. Mech. Engr. (1965-66), vol. 180 Pt. 1 No. 15, pp. 371-378.
Griffis and Duffy, "A Forward Displacement Analysis of a Class of Stewart Platforms", Journal of Robotic Systems vol. 6, No. 6, pp. 703-720 (1989).
(18 pages)
Nanua et al., "Direct Kinematic Solution of a Stewart Platform", 1989 IEEE Intl. Conf. on Robotics and Automation, Scottsdale, Ariz. (May 1989), pp. 431-437.
Miura et al., "Variable Geometry Truss and its Application to Deployable Truss and Space Crane Arm", Proc. 35th Congress of the International Astronautical Federation, American Institute of Aeronautics and Astronautics, Oct. 7-13, 1984, pp. 1-9.
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