Surgical tool
A medical instrument may include multiple joint members and at least two pairs of tendons connected with the joint members and adapted to move at least one of the joint members relative to at least one other joint member. Each joint member may include a main structural body that may be a single piece and includes at least one convex contact surface. A main portion of each tendon contacts the medical instrument only on the convex contact surfaces.
1. A medical instrument for robotic surgery, the medical instrument comprising:
a frame;
a shaft having a proximal end attached to the frame and a distal end;
a jointed device attached to the distal end of the shaft, the jointed device comprising:
a first link connected to the frame through the shaft;
a second link connected via a first rotational joint to the first link;
a third link connected via a second rotational joint to the second link;
a first pair of tendons connected to the third link to pull on the third link and thus move the third link with respect to the second link; and
at least a second pair of tendons connected to the second link to pull on the second link and thus move the second link with respect to the first link,
wherein each link comprises a main, one-piece structural body having one or more convex contact surfaces,
wherein each of the convex contact surfaces is a convex ruled surface formed by multiple straight line portions that are parallel to each other and parallel to a joint movement axis of the first rotational joint or the second rotational joint,
wherein each tendon of the first and second pairs of tendons comprises:
a first tendon endpoint, coupled with the frame;
a second tendon endpoint, secured to the second link or to the third link; and
a tendon main portion, extending between the first tendon endpoint and the second endpoint,
wherein the tendon main portion of each tendon of the first and second pairs of tendons contacts the jointed device only onto the convex contact surfaces, so that only the convex contact surfaces of the links are in contact with the tendon main portion, and
wherein the main tendon portion of at least two tendons of the first and second pairs of tendons slides onto a same convex contact surface.
2. The medical instrument of claim 1 , wherein the second link defines two rotational joints having rotational axes orthogonal to each other.
3. The medical instrument of claim 1 , wherein the second link defines two rotational joints having rotational axes parallel to each other.
4. The medical instrument of claim 1 , wherein all the convex contact surfaces and any prolongations thereof define at least partially a single convex volume for each link, thereby the convex contact surfaces of a given link form together a portion of the external surface of the given link.
5. The medical instrument of claim 1 , wherein none of the convex contact surfaces comprises a channel.
6. The medical instrument of claim 1 , wherein both tendons of a pair of tendons are secured to a same link contact, with the tendon main portion thereof, a same convex contact surface of an another link which is upstream the link to which the tendons of a pair of tendons are secured.
7. The medical instrument of claim 1 , wherein the main structural body of each link is a rigid body.
8. The medical instrument of claim 1 , wherein the jointed device further comprises a fourth link.
9. The medical instrument of claim 8 , wherein the fourth link is connected to a single rotational joint to both the third link and the second link, wherein the third link and the fourth link together form a terminal device selected from the group consisting of cutters and grippers.
10. The medical instrument of claim 8 , further comprising a third pair of tendons.
11. The medical instrument of claim 8 , further comprising an additional link connected to both the first link and the second link, wherein the additional link defines two rotational joints having rotational axes parallel to each other.
12. The medical instrument of claim 8 , wherein the third pair of tendons is adapted to move the fourth link around a rotational joint.
13. The medical instrument of claim 8 , wherein both tendons of a pair of tendons secured to a same link are designed to move the same link in opposite rotational directions.
14. The medical instrument of claim 8 , wherein the two tendons of a pair of tendons are parallel to each other over a length of their tendon main portion and are both in contact with a the same convex contact surface of the first link, and are both in contact with a the same convex contact surface of the second link.
15. The medical instrument of claim 1 , wherein the tendons of the pair of tendons connected to the third link slide onto the convex contact surfaces of the second link.
16. The medical instrument of claim 1 , wherein tendon termination seats for the first and second pairs of tendons are positioned to maintain each tendon sliding on a same path onto the convex contact surfaces.
17. The medical instrument of claim 1 , wherein each of the second link and the third link has a pair of tendon termination seats coupled with the second tendon endpoints of a pair of tendons, and wherein the termination seats of each link maintain the tendons parallel to each other and orthogonal to the rotational axis of a closest rotational joint of the jointed device.
18. The medical instrument of claim 14 , wherein at least one section of the tendon main portion of each tendon runs between two adjacent convex contact surfaces to define at least one portion of each tendon that does not contact any links.
19. The medical instrument of claim 1 , wherein the tendon main portion of each tendon wraps around the convex contact surfaces.
20. The medical instrument of claim 1 , wherein the tendons of each of the first and second pairs of tendons cross paths without touching.
21. The medical instrument of claim 1 , wherein the tendons of the pair of tendons connected to the third link wrap around a convex contact surface of the first link and wrap around a convex contact surface of the second link.
22. The medical instrument of claim 1 , wherein the portions of the tendons contacting a same convex contact surface are parallel to each other.
23. The medical instrument of claim 1 , further comprising a motor compartment upstream to the frame accommodating at least one actuator for driving the first and second pairs of tendons of the jointed device.
24. The medical instrument of claim 23 , further comprising a sterile barrier interposed between the motor compartment and the frame.
25. The medical instrument of claim 1 , wherein the main tendon portion of the two tendons of the first pair of tendons slides onto a same convex contact surface of the second link.