Operating self-antagonistic drives of medical instruments
A medical instrument including a shaft and an actuated structure mounted at a distal end of the shaft can employ a pair of tendons connected to the actuated structure, extending down the shaft, and respectively wound around a capstan in opposite directions. A passive preload system may maintain minimum tensions in the tendons.
1. A medical instrument comprising:
a shaft;
an actuated structure mounted at a distal end of the shaft in a manner that permits movement of the actuated structure relative to the shaft;
a first tendon connected to the actuated structure and extending down the shaft;
a second tendon connected to the actuated structure and extending down the shaft;
a capstan at a proximal end of the shaft, wherein a portion of the first tendon is wound around the capstan in a first direction, and a portion of the second tendon is wound around the capstan in a second direction that is opposite of the first direction; and
a preload system coupled to permit linear movement of the capstan in a direction perpendicular to a rotational axis of the capstan.
2. The instrument of claim 1 , wherein the preload system includes a spring loaded mounting coupled to the capstan that permits the linear movement of the capstan.
3. The instrument of claim 1 , comprising a motor coupled to the capstan to rotate the capstan.
4. The instrument of claim 3 , wherein the motor includes a slide mounting.
5. The instrument of claim 4 , wherein the preload system is coupled to the slide mounting of the motor.
6. The instrument of claim 3 , comprising a hand-operated manipulator coupled to the capstan to enable manual rotation of the capstan in addition to the motor operated rotation of the capstan.
7. The instrument of claim 6 , wherein the hand-operated manipulator includes a knob or a lever.
8. The instrument of claim 6 , wherein the preload system is coupled to the hand-operated manipulator.
9. The instrument of claim 1 , comprising a hand-operated manipulator coupled to the capstan to enable manual rotation of the capstan.
10. The instrument of claim 9 , wherein the hand-operated manipulator includes a knob or a lever.
11. The instrument of claim 9 , wherein the preload system is coupled to the hand-operated manipulator.
12. The instrument of claim 1 , wherein the capstan includes bearings.
13. The instrument of claim 12 , wherein the preload system is coupled to the bearings.
14. The instrument of claim 1 , wherein proximal ends of first and second tendons are fixed on the capstan.