Robotic leg
A robotic leg includes a hip, a first pulley attached to the hip and defining a first axis of rotation, a first leg portion having a first end portion and a second end portion, a second pulley rotatably coupled to the second end portion of the first leg portion and defining a second axis of rotation, a second leg portion having a first end portion and a second end portion, and a timing belt trained about the first pulley and the second pulley for synchronizing rotation of the first leg portion about the first axis of rotation and rotation of the second leg portion about the second axis of rotation. The first end portion of the first leg portion is rotatably coupled to the hip and configured to rotate about the first axis of rotation. The first end portion of the second leg portion is fixedly attached to the second pulley.
1. A robotic leg comprising:
a first leg portion having a first end portion having a first axis of rotation and a second end portion having a second axis of rotation;
a second leg portion having a first end portion and a second end portion, the first end portion rotatably coupled to the second end portion of the first leg portion for rotation about the second axis of rotation; and
a coupler coupling rotation of the first leg portion about the first axis of rotation to rotation of the second leg portion about the second axis of rotation, the coupling providing a greater rotation of the second leg portion about the second axis of rotation in a first direction than the rotation of the first leg portion about the first axis of rotation in a second direction, the first and second directions being opposite directions.
2. The robotic leg of claim 1 , wherein the coupler comprises:
a first pulley rotatably coupled to the first end portion of the first leg portion, the first pulley defining the first axis of rotation;
a second pulley rotatably coupled to the second end portion of the first leg portion, the second pulley defining the second axis of rotation; and
a timing belt trained about the first pulley and the second pulley for synchronizing rotation of the first leg portion about the first axis of rotation and rotation of the second leg portion about the second axis of rotation.
3. The robotic leg of claim 2 , wherein the first pulley is rotationally fixed relative to an end of the first end portion of the first leg portion.
4. The robotic leg of claim 1 , wherein the first leg portion defines a longitudinal axis, the first axis of rotation is perpendicular to the longitudinal axis, and the second axis of rotation is perpendicular to the longitudinal axis.
5. The robotic leg of claim 1 , further comprising a rotary motor arranged to drive rotation of the first leg portion about the first axis of rotation.
6. The robotic leg of claim 5 , wherein the rotary motor defines a rotary axis coincident with the first axis of rotation.
7. The robotic leg of claim 1 , wherein the first axis of rotation is parallel to the second axis of rotation.
8. The robotic leg of claim 2 , wherein the first pulley and the second pulley are sized to provide a 2:1 ratio of the rotation of the second leg portion about the second axis of rotation to the rotation of the first leg portion about the first axis of rotation.
9. The robotic leg of claim 2 , wherein:
an outer circumferential surface of the first pulley comprises teeth;
an outer circumferential surface of the second pulley comprises teeth; and
a surface of the timing belt comprises teeth configured to engage with the teeth of the first pulley and the teeth of the second pulley.
10. The robotic leg of claim 9 , wherein the first pulley has 60 teeth and the second pulley has 30 teeth.
11. The robotic leg of claim 1 , wherein a length of the first leg portion is substantially equal to a length of the second leg portion.
12. The robotic leg of claim 6 , wherein the rotary motor comprises:
a rotor arranged to rotate about the rotary axis, the rotor attached to the first leg portion; and
a stator arranged concentrically around the rotor.
13. The robotic leg of claim 1 , wherein the coupler is configured such that the rotation of the second leg portion in the first direction is at least double the rotation of the first leg portion in the second direction.
14. The robotic leg of claim 3 , wherein the second pulley is rotationally fixed relative to the first end of the second leg portion.
15. The robotic leg of claim 2 , further comprising a belt tensioner configured to tension the timing belt.
16. The robotic leg of claim 15 , wherein the belt tensioner is positioned on the first leg portion.
17. The robotic leg of claim 2 , wherein a diameter of the first pulley is greater than a diameter of the second pulley.
18. The robotic leg of claim 17 , wherein the diameter of the first pulley is at least twice as large as the diameter of the second pulley.
19. The robotic leg of claim 1 , further comprising a linear actuator configured to drive rotation of the first leg portion.
20. The robotic leg of claim 19 , wherein the linear actuator comprises a translatable actuator arm pivotally coupled to the first leg portion.