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US 6,840,127 B2Granted
Tendon link mechanism with six degrees of freedom
OwnerMichael Julius Moraninventor
Life of this patent
Estimating the term…
Abstract
A computer-controlled parallel-leg mechanism, with three pairs of remotely-actuated tendon legs, provides accurate six-degrees-of-freedom motion and positioning for a tool platform. Leg pair termination at a common point with three degrees of pivoting freedom is provided by a unique linkage joint. Non-intrusive tool-position feedback is enabled by nine shaft encoders mounted at the mechanism's base end.
Claims10
A method for creating a variable-length mechanism link possessing pivoting freedom about an invariable-and-known end point, comprising the steps of:
- a. joining a first link to a second link with a first revolute joint having a first axis of rotation, and
- b. joining a third link to said second link with a second revolute joint having a second axis of rotation, such that said second axis of rotation is orthogonal to, and intersects, said first axis of rotation, and such that said third link's line vector intersects said first axis of rotation and said second axis of rotation at their point of intersection, and
- c. attaching a tendon-length-controlling actuator and a first segment of a constrained tendon path to said first link, such that said first segment proceeds from said actuator to become collinear with said first axis of rotation, and
- d. attaching a second segment of said constrained tendon path to said second link, such that said second segment changes from being collinear with said first axis to become collinear with said second axis of rotation, and
- e. attaching a third segment of said constrained tendon path to said third link, such that said third segment changes from being collinear with said second axis to become collinear with said third link's line vector, and
- f. attaching a tendon to said actuator, and threading said tendon along said first segment and then along said second segment and then along said third segment, for a distance determined by said third link's required length, to terminate with a tensile force load,
- whereby said tendon remains in tension throughout said path.
4 more elements
A variable-length mechanism link, possessing pivoting freedom about an invariable-and-known end point, comprising:
- a. a first link joined to a second link with a first revolute joint having a first axis of rotation, and
- b. a third link joined to said second link with a second revolute joint having a second axis of rotation, such that said second axis of rotation is orthogonal to, and intersects, said first axis of rotation, and such that said third link's line vector intersects said first axis of rotation and said second axis of rotation at their point of intersection, and
- c. a tendon-length-controlling actuator and a first segment of a constrained tendon path, both rigidly affixed to said first link, such that said first segment proceeds from said actuator to become collinear with said first axis of rotation, and
- d. a second segment of said constrained tendon path rigidly affixed to said second link, such that said second segment changes from being collinear with said first axis to become collinear with said second axis of rotation, and
- e. a third segment of said constrained tendon path rigidly affixed to said third link, such that said third segment changes from being collinear with said second axis to become collinear with said third link's line vector, and
- f. a tendon, attached to said actuator, and threaded along said first segment and then along said second segment and then along said third segment, for a distance determined by said third link's required length, to terminate with a tensile force load,
- whereby said tendon remains in tension throughout said path.
4 more elements
A parallel-leg mechanism, comprising:
- a. a base structure, and
- b. a plurality of tendon legs joined to said base structure by a first means for providing a base leg end for each of said legs, such that said base leg end is known, invariable, and possesses two degrees of rotational freedom, with respect to said base structure, and such that said base leg ends are disposed at predetermined points on a base triangle, and
- c. a platform joined to each of said legs by a second means for providing a platform leg end for each of said legs, such that said platform leg end is known, invariable, and possesses pivoting freedom, with respect to said platform, and such that said platform leg end is common to two of said legs, and such that the leg ends are disposed to form a triangle that is fixed relative to said platform, and
- d. a third means for providing tensile force loading in combination with each platform leg end, whereby each of said legs is in tension, and
- e. associated with each of said legs, a tendon attached to a controllable actuator, such that controlled extension and retraction of said tendon is obtained, and
- f. said tendon in combination with a fourth means for kinematically constraining the path of said tendon, such that said actuator is able to controllably change the length of said leg between said base leg end and said platform leg end,
- whereby said platform can be moved and positioned with six degrees of freedom.
4 more elements
Dependencies are inferred from the claim text.