Systems and methods for articulating an elongate body

1. A system for modifying an articulating force on an articulatable elongate body deliverable within a body cavity, the system comprising:

an elongate body comprising an articulatable segment, wherein the articulatable segment comprises

a plurality of links having central apertures that collectively form an internal lumen of the segment, and

a cross bar member coupled to at least one of the links and comprising at least one force modifying element, wherein the cross bar member is disposed within and extends transversely across the internal lumen;

a coil pipe within the elongate body having a proximal end terminated outside of the elongate body and having a distal end terminated at a proximal portion of the segment; and

a tendon disposed at least partially within the coil pipe, the tendon having a proximal end and a distal end, wherein the proximal end is coupled to an actuator outside of the elongate body, wherein the tendon interacts with the force modifying element, and wherein the distal end is coupled to a link proximal to the force modifying element.

2. The system of claim 1 wherein the force modifying element is disposed at a distal portion of the segment.

3. The system of claim 1 wherein the distal end of the tendon is coupled to a proximal portion of the segment.

4. The system of claim 1 wherein the coil pipe and the distal end of the tendon are coupled to the same link.

5. The system of claim 1 wherein the segment comprises a plurality of cross bar members, each cross bar member being coupled to a respective one of the plurality of links and comprising at least one force modifying element,

and wherein the system comprises a plurality of tendons each coupled at their proximal ends to the actuator and disposed to interact with a respective force modifying element.

6. The system of claim 5 wherein the plurality of tendons is at least three tendons.

7. The system of claim 1 wherein the force modifying element comprises a curved surface and wherein the tendon and force modifying element slidingly interact.

8. The system of claim 7 wherein the curved surface is a fixed curved surface.

9. The system of claim 7 wherein the tendon loops around the curved surface.

10. The system of claim 1 wherein at least one link is adapted to move in response to an actuation force to control articulation without being locked in position relative to an adjacent link.

11. The system of claim 1 , wherein adjacent links are articulably coupled to each other at joints.

12. The system of claim 11 , wherein the cross bar member is axially disposed between two adjacent links and coupled to the joints of the adjacent links.

13. The system of claim 12 , wherein the cross bar member is hingedly coupled to the joints of the adjacent links.

14. The system of claim 1 , wherein the cross bar member is hingedly coupled to the at least one link.

15. The system of claim 1 , wherein the cross bar member is fixedly coupled to the at least one link.

16. The system of claim 1 , wherein the cross bar member is integral with the at least one link.

17. The system of claim 1 , wherein the force modifying element comprises a tendon attachment structure.

18. The system of claim 1 , wherein the system comprises a plurality of coil pipes and the plurality of links comprise a plurality of proximal links and a plurality of distal links, and

wherein a first set of coil pipes is attached to a first cross bar member that is positioned between a first link and a second link of the proximal links, and a second set of coil pipes is attached to a second cross bar member that is positioned between the second link and a third link of the proximal links, and

wherein the first set of coils pipes is offset 90 degrees from the second set of coil pipes.

19. The system of claim 18 ,

wherein the system comprises a plurality of force modifying elements,

wherein a first set of force modifying elements is coupled to a third cross bar member that is positioned between a first link and a second link of the distal links, and a second set of force modifying elements is coupled to a fourth cross bar member that is positioned between the second link and a third link of the distal links, and

wherein the first set of force modifying elements is offset 90 degrees from the second set of force modifying elements.

20. The system of claim 19 ,

wherein the system comprises a plurality of tendons,

wherein a first set of tendons extends from the first set of coil pipes and interacts with the first set of force modifying elements, and

wherein a second set of tendons extends from the second set of coil pipes and interacts with the second set of force modifying elements.

21. The system of claim 1 , wherein the cross bar member comprises at least one hole through which the tendon is routed axially along the segment.

22. The system of claim 1 , wherein the cross bar member comprises at least one hole, and wherein a coil pipe is coupled to the cross bar member at the at least one hole.