Surgical tool for robotic surgery and robotic surgical assembly
A robotic surgery assembly includes a medical instrument having a frame, a jointed device having a degree of freedom with respect of the frame, and at least one tendon made of polymer fibers configured for actuating the degree of freedom. The tendon includes a tendon endpoint connected to the medical instrument to exert a tensile load for actuating the degree of freedom.
1. A robotic surgery assembly comprising a medical instrument comprising:
a frame;
a jointed device having a rotational joint and a terminal member attached to the rotational joint, the jointed device defining a degree of freedom with respect of said frame; and
at least one tendon made of polyethylene fibers for actuating said degree of freedom, wherein said at least one tendon slides while in contact with at least one portion of said jointed device to actuate said rotational joint;
wherein said tendon comprises a tendon endpoint connected to the jointed device to exert a tensile load for actuating said degree of freedom, wherein said tendon endpoint is secured to the terminal member of the jointed device; and
wherein tendon stiffness varies along the length of said at least one tendon;
wherein the terminal member comprises a winding surface onto which the tendon is wrapped around, wherein said winding surface is a ruled surface formed by a plurality of portions of straight lines, and wherein all of the straight lines are parallel to a rotational axis of the rotational joint.
2. The assembly of claim 1 , wherein said at least one tendon is made of strands.
3. The assembly of claim 2 , wherein the at least one tendon is made of braided strands, the strands comprising said polyethylene fibers.
4. The assembly of claim 3 , wherein said at least one tendon has a pick per inches (PPI) of 20-60.
5. The assembly of claim 3 , wherein the PPI of said at least one tendon is higher at a distal portion of said at least one tendon than at a proximal portion of said at least one tendon, said distal portion being located near said tendon endpoint.
6. The assembly of claim 5 , wherein said distal portion having higher PPI has length equal or less than ⅓ of a length of said at least one tendon.
7. The assembly of claim 5 , wherein said distal portion having higher PPI has a length equal or less than 1/10 of a length of said at least one tendon.
8. The assembly of claim 5 , wherein said distal portion having higher PPI has a length equal or less than 1/20 of a length of said at least one tendon.
9. The assembly of claim 2 , wherein said at least one tendon is made of strands having different dimensions or sizes.
10. The assembly of claim 1 , wherein said at least one tendon have an elastic module between 50 GPa and 100 GPa.
11. The assembly of claim 1 , wherein the jointed device comprises a tendon fastening point where the tendon endpoint is connected, wherein the frame comprises a shaft, and wherein said at least one tendon is more flexible proximate or at a tendon fastening point and is stiffer close to or inside said shaft.
12. The assembly of claim 1 , wherein said at least one tendon comprises a distal portion located proximate the tendon endpoint, said distal portion is braided with PPI of 25-100.
13. The assembly of claim 1 , wherein said at least one tendon comprises a longitudinal portion which is braided with PPI of 3-25.
14. The assembly of claim 1 , wherein said at least one tendon has a curvature radius inferior or equal to one millimeter.
15. The assembly of claim 1 , wherein said at least one tendon has a diameter, variable in different portions thereof.
16. The assembly of claim 15 , wherein said at least one tendon is thinner at said tendon endpoint.
17. The assembly of claim 1 , wherein said at least one tendon has diameter between 0.05 mm and 0.3 mm.
18. The assembly of claim 1 , wherein said at least one tendon comprises a distal portion located proximate the tendon endpoint, said distal portion is braided with PPI of 50-100.
19. The assembly of claim 1 , wherein said at least one tendon is pre-lengthened.
20. The assembly of claim 1 , wherein the medical instrument comprises a mechanical transmission box and a hollow shaft extending between the frame and the terminal member, and wherein the tendon extends through the mechanical transmission box and the hollow shaft to connect to the terminal member.
21. The assembly of claim 1 , wherein the medical instrument comprises one opposite tendon forming a pair of tendons with said tendon, said tendon and said opposite tendon comprising endpoints, said tendon and said opposite tendon being connected at the endpoints to the terminal member to move the terminal member around a rotational axis of the rotational joint in opposite directions.
22. A robotic surgery assembly comprising a medical instrument comprising:
a frame;
a jointed device having a rotational joint and a terminal member attached to the rotational joint, the jointed device defining a degree of freedom with respect of said frame; and
at least one tendon made of polyethylene fibers for actuating said degree of freedom, wherein said at least one tendon slides while in contact with at least one portion of said jointed device to actuate said rotational joint;
wherein said tendon comprises a tendon endpoint connected to the jointed device to exert a tensile load for actuating said degree of freedom;
wherein said tendon endpoint is secured to the terminal member of the jointed device;
wherein tendon stiffness varies along the length of said at least one tendon; and
wherein said at least one portion of the jointed device on which said at least one tendon slides while in contact is formed by a convex, ruled surface formed by a plurality of straight generator lines parallel to a rotational axis of said rotational joint.