Articulatable members having constrained motion and related devices and methods
An articulatable member includes a distal end, a proximal end, an actuation member, and a constraint member. The actuation member extends from the proximal end to the distal end. The actuation member transmits force to bend the articulatable member from a neutral position. The constraint member extends from the proximal end to the distal end. The constraint member may have opposite ends that are fixed to the distal end and the proximal end. In one embodiment, the constraint member follows a helical path along at least a portion of the articulatable member from the proximal end to the distal end. In another embodiment, the actuation member follows a helical path along at least a portion of the articulatable member.
1. An articulatable member, comprising:
a plurality of links extending in a series from a proximal end link to a distal end link, adjacent links of the plurality of links being pivotably coupled to form joints between adjacent links;
an actuation member extending from the proximal end link to the distal end link,
wherein the actuation member is operably coupled to the plurality of links to transmit force to bend the articulatable member from a neutral position; and
a constraint member extending from the proximal end link to the distal end link,
wherein the constraint member has opposite ends that are fixed to the distal end link and the proximal end link, respectively,
wherein the constraint member extends through a throughhole in each link of the plurality of links, the throughhole being radially offset from a central axis of the link, and
wherein the constraint member follows a helical path along at least a portion of the articulatable member from the proximal end link to the distal end link;
wherein, in a straight configuration of the articulatable member, the constraint member is under tensile force between the opposite ends.
2. The articulatable member of claim 1 , wherein the articulatable member is a wrist.
3. The articulatable member of claim 1 , wherein the constraint member is arranged to passively constrain translation motion of the plurality of links.
4. The articulatable member of claim 1 , wherein the actuation member extends substantially straight along the articulatable member from the distal end link to the proximal end link.
5. The articulatable member of claim 1 , wherein rotational axes of consecutive joints of the joints between adjacent links are oriented orthogonally to each other.
6. The articulatable member of claim 5 , wherein an angular extent of the helical path of the constraint member between adjacent links of the plurality of links is about 90 degrees.
7. The articulatable member of claim 5 , wherein the constraint member comprises a plurality of constraint members, wherein a helical path of a first constraint member of the plurality of constraint members is right-handed, and wherein a helical path of a second constraint member of the plurality of constraint members is left-handed.
8. The articulatable member of claim 1 ,
wherein the joints between adjacent links comprise two consecutive joints and two flanking joints, a first of the two flanking joints flanking a first of the two consecutive joints, and a second of the two flanking joints flanking a second of the two consecutive joints,
wherein each of the two consecutive joints has a rotational axis that extends in substantially a same direction, and
wherein each of the flanking joints has a rotational axis that extends in a direction substantially orthogonal to the direction of the rotational axes of the two consecutive joints.
9. The articulatable member of claim 8 , wherein an angular extent of the helical path of the constraint member between the two consecutive joints is about 180 degrees.
10. The articulatable member of claim 1 , wherein the constraint member is part of a braided structure.
11. The articulatable member of claim 10 , wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 180 degrees.
12. The articulatable member of claim 10 , wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 360 degrees.
13. The articulatable member of claim 10 , wherein an angular extent of the braided structure between a distal end and a proximal end of the braided structure is about 720 degrees.
14. The articulatable member of claim 10 , further comprising a member disposed internal to the braided structure and a member disposed external to the braided structure to limit expansion and contraction of the braided structure.
15. The articulatable member of claim 10 , wherein the braided structure forms a body structure of the articulatable member from the proximal end link to the distal end link.
16. The articulatable member of claim 10 , wherein the braided structure constrains motion of the plurality of links.
17. The articulatable member of claim 1 , wherein the articulatable member is a wrist of a surgical instrument.
18. The articulatable member of claim 1 , further comprising:
a plurality of actuation members, wherein the actuation member is one of the plurality of actuation members; and
a plurality of constraint members, wherein the constraint member is one of the plurality of constraint members.
19. The articulatable member of claim 1 , wherein the plurality of links further comprises at least one intermediate link between the proximal end link and the distal end link.
20. A surgical instrument, comprising:
a shaft;
a force transmission mechanism connected to a proximal end of the shaft;
a parallel motion mechanism connected to a distal end of the shaft;
a wrist comprising a plurality of links, the wrist being coupled to a distal end of the parallel motion mechanism;
an actuation member operably coupled to transmit force from the force transmission mechanism to bend the wrist from a neutral position; and
a constraint member extending through the wrist and the parallel motion mechanism, the constraint member arranged to passively constrain motion of the wrist and the parallel motion mechanism;
wherein opposite ends of the constraint member are respectively fixed to a distal end of the wrist and a proximal end of the parallel motion mechanism;
wherein a portion of the constraint member between the opposite ends is fixed to a portion of the surgical instrument between the wrist and the parallel motion mechanism; and
wherein the constraint member follows a substantially straight path along the parallel motion mechanism and a helical path along at least a portion of the wrist.
21. The surgical instrument of claim 20 , further comprising an end effector coupled to a distal end of the wrist.
22. The surgical instrument of claim 20 ,
wherein the actuation member is operably coupled to the force transmission mechanism and the wrist so as to transmit the force from the force transmission mechanism to bend the wrist, and
wherein the actuation member extends in a substantially straight path along the parallel motion mechanism and the wrist.
23. The surgical instrument of claim 20 ,
wherein the actuation member is operably coupled to the force transmission mechanism and the parallel motion mechanism to transmit the force from the force transmission mechanism to bend the parallel motion mechanism, and
wherein the actuation member follows a helical path along at least a portion of the parallel motion mechanism.