Spherical robotic shoulder joint
AssigneeKung C. Wu
InventorsKung C. Wu, Rex Melgoza
Life of this patent
Estimating the term…
Abstract
A two-degree-of-freedom spherical shoulder joint for a robot. The joint consists of a spherical ball member with gear teeth formed in its outer surface and three drive gears that mate with the gear teeth in the outer surface of the spherical member. The joint can rotate about any axis of rotation which lies within a plane defined by the contact points between the drive gears and the spherical member. By controlling the three drive gears to rotate by the proper amounts, the joint can be rotated about the desired axis of rotation. The inverse kinematics for controlling the joint are described.
Claims20
A spherical joint comprising:
- a generally spherical member having a geometric center and an outer surface
- three drive means, each of which contacts said outer surface at a respective contact point, wherein said contact points and said geometric center are located within and define a plane, and wherein said drive means impart movement to said outer surface, whereby said spherical member is capable of being rotated about any axis of rotation which lies within said plane.
A spherical joint comprising:
- a generally spherical member having a geometric center and an outer surface, said outer surface being formed with gear teeth therein,
- a plurality of drive gears, each of which mates with said gear teeth in said outer surface at a respective contact point, wherein said contact points and said geometric center are located within and define a plane, and wherein said drive means impart movement to said outer surface, whereby said spherical member is capable of being rotated about any axis of rotation which lies within said plane.
A spherical joint comprising:
- a generally spherical member having a geometric center and an outer surface, said outer surface being formed with gear teeth therein,
- three drive means, each of which comprises a drive gear that mates with said gear teeth in said outer surface and which impart movement to said outer surface, whereby said spherical member is capable of being rotated about an infinite number of axes which pass through said geometric center.
A robotic joint comprising:
- a driven member which is rotated about an arbitrary axis of rotation n within an X-Y plane, said axis of rotation having X and Y components n.sub.x and n.sub.y,
- three driving members, and
- control means which rotates said driven member through an angle .theta. about said axis of rotation by rotating the three driving members through angles .theta..sub.1, .theta..sub.2, and .theta..sub.3 respectively, wherein the angles .theta..sub.1, .theta..sub.2, and .theta..sub.3 are defined by the equations:
- .theta..sub.1 =C cos.sup.-1 (1-n.sub.y.sup.2 (1-cos .theta.))
- .theta..sub.2 =C cos.sup.-1 (1-.gamma..sup.2 (1-cos .theta.))
- .theta..sub.3 =C cos.sup.-1 (1-.eta..sup.2 (1-cos .theta.))
- where C is a ratio of rotation in the driving members to rotation in the driven member and where .gamma. and .eta. are defined by the equations:
- .gamma.=n.sub.y cos (2/3.pi.)+n.sub.x sin (2/3.pi.)
- .eta.=n.sub.y cos (4/3)+n.sub.x sin (4/3.pi.).
Dependencies are inferred from the claim text.