Instruments for mechanized surgical system

1. A surgical instrument for use with a mechanized surgical system having a roll drive unit operable by a motor, the surgical instrument comprising:

an elongate shaft having a longitudinal axis and a distal end;

an end effector on the shaft, the end effector including jaws mounted on the distal end of the shaft, the jaws moveable between open and closed;

a handle on the shaft, the handle including an actuator manually operable by a user to move the jaws of the end effector between the open and closed positions;

wherein the shaft includes a distal shaft portion, and a proximal shaft portion, the distal shaft portion and the proximal shaft portion coupled together along the longitudinal axis by a roll joint forming a part of the shaft and proximally spaced from the end effector such that the distal shaft portion is rotatable relative to the proximal shaft portion about the longitudinal axis at the roll joint; and

wherein the instrument is configured to be removably mountable during the course of a surgical procedure in operative engagement with a roll drive unit of a mechanized surgical system operable by a motor and wherein the instrument further includes a drive segment on the distal shaft portion, the drive segment having an exterior surface and circumferentially spaced apart ribs extending radially outwardly from the exterior surface, each of the ribs extending longitudinally along the surface of the drive segment and extending parallel to a longitudinal axis of the drive segment the ribs rotationally engageable with second features of the roll drive unit such that operation of the motor causes the distal shaft portion to axially roll relative to the proximal shaft portion and the handle, wherein the drive segment has a non-circular transverse perimeter, first features defined by the non-circular transverse perimeter.

2. The surgical instrument of claim 1 , wherein the ribs are shaped to permit longitudinal movement of the shaft relative to the roll drive unit when the ribs and second features are rotationally engaged.

3. The surgical instrument of claim 1 , where the ribs are longitudinal spline elements.

4. The surgical instrument of claim 1 , wherein the spline elements have tapered distal ends.

5. The surgical instrument of claim 1 , wherein the shaft has a first diameter and the drive segment has a second diameter larger than the first diameter.

6. The surgical instrument of claim 5 , wherein a distal end of the drive segment is chamfered.

7. The surgical instrument of claim 1 , wherein the proximal shaft portion is an elongate section of shaft distal to the handle.

8. The surgical instrument of claim 7 , wherein the proximal shaft portion includes a first elongate section adjacent to the handle and a second elongate section between the handle and the roll joint, the first elongate section having a diameter that is larger than a diameter of the second elongate section.

9. The surgical instrument of claim 1 , wherein the surgical instrument is for use with a mechanized surgical system having a command interface, and wherein the surgical instrument is positionable in contact with the command interface.

10. The surgical instrument of claim 9 , wherein the surgical instrument further includes an element proximally positioned on the surgical instrument, the element detectable by the command interface as an indication of the presence of positioning of the instrument in contact with the command interface.

11. The surgical instrument of claim 1 , further including a collar on the instrument shaft, distally adjacent to the handle.

12. The surgical instrument of claim 11 , further including a distally-facing magnet on the collar.