Belt termination and tensioning in a pulley arrangement for a robotic arm
In one variation, a pulley arrangement includes a base pulley portion rotatable within a driving plane, an adjustable pulley portion coupled to the base pulley portion wherein the adjustable pulley portion is rotatable relative to the base pulley portion within the driving plane, and a driving member including an end coupled to the adjustable pulley portion wherein at least a portion of the driving member is wrapped at least partially around the adjustable pulley portion. In another variation, a pulley arrangement includes a base pulley portion rotatable around an axis, an adjustable pulley portion coupled to the base pulley portion and movable in a first direction parallel to the axis, and a sliding block engaged with the adjustable pulley portion, wherein the sliding block moves in a second direction different from the first direction, in response to compression of the adjustable pulley portion against the base pulley portion.
1. A pulley arrangement, comprising:
a base pulley portion rotatable within a driving plane;
an adjustable pulley portion coaxially coupled to the base pulley portion, wherein the adjustable pulley portion is rotatable relative to the base pulley portion within the driving plane;
a driving member comprising a first end coupled to the adjustable pulley portion, wherein at least a portion of the driving member is wrapped at least partially around the adjustable pulley portion; and
a movable element engaged with the adjustable pulley portion and adjustable to thereby rotate the adjustable pulley portion relative to the base pulley portion, and wherein the movable element comprises a threaded member threadingly attached to the base pulley portion.
2. The pulley arrangement of claim 1 , wherein the adjustable pulley portion is lockable in a selected rotational position relative to the base pulley portion, thereby setting a selected tension in the driving member.
3. The pulley arrangement of claim 1 , wherein the adjustable pulley portion is coupled to the base pulley portion via at least one opening in at least one of the adjustable pulley portion and the base pulley portion.
4. The pulley arrangement of claim 3 , further comprising a fastener passing through the at least one opening, wherein the fastener is lockable in the at least one opening to thereby lock a rotational position of the adjustable pulley portion relative to the base pulley portion.
5. The pulley arrangement of claim 4 , wherein the at least one opening is a slot and wherein the fastener is lockable in a selected location within the slot to thereby lock the rotational position of the adjustable pulley portion relative to the base pulley portion.
6. The pulley arrangement of claim 4 , wherein the at least one opening is one of a plurality of openings in at least one of the adjustable pulley portion and the base pulley portion, each opening corresponding to a respective rotational position of the adjustable pulley portion relative to the base pulley portion, and wherein the fastener is lockable in the at least one opening to thereby lock the rotational position of the adjustable pulley portion relative to the base pulley portion.
7. The pulley arrangement of claim 1 , wherein the threaded member comprises a hemi-spherical head contacting the adjustable pulley portion.
8. The pulley arrangement of claim 1 , further comprising a second pulley, wherein the driving member wraps at least partially around an idler pulley.
9. The pulley arrangement of claim 8 , wherein the second pulley is a fixed distance from the base pulley portion.
10. The pulley arrangement of claim 1 , wherein the driving member comprises a second end coupled to the second pulley.
11. The pulley arrangement of claim 10 , further comprising a second driving member comprising a third end coupled to the base pulley portion and a fourth end coupled to the second pulley.
12. The pulley arrangement of claim 1 , wherein the adjustable pulley portion comprises an arcuate member that is coaxial with the base pulley portion.