Surgical instrument steering input device
A drive assembly of an instrument includes an input drive interface removably engageable with an external actuator device and configured to receive drive actuation force from the external actuator device in a state of engagement with the external actuator device, a drive shaft configured to be driven in rotation, a capstan, and a splined snap-fit connection mechanism between the drive shaft and the capstan. The splined snap-fit connection mechanism includes splined engagement features configured to engage each other so as to prevent relative rotation between the drive shaft and the capstan, and a plurality of snap-fit elements to provide a snap-fit engagement between the drive shaft and the capstan so as to provide resistance to relative axial movement between the drive shaft and the capstan.
1 . A method for assembling a drive assembly for transmitting actuation force to a surgical instrument end effector coupled to an instrument shaft via cable tensioning, the method comprising:
coupling, to a drive shaft of the drive assembly, a first cable portion of a drive cable, the drive cable extending along the instrument shaft and operably coupled to the end effector,
coupling, to a capstan of the drive assembly, a second cable portion of the drive cable,
independently rotating the drive shaft relative to the capstan to draw the drive cable into tension, and
securing the capstan and the drive shaft in a fixed rotational relationship with each other via a splined snap-fit connection mechanism.
2 . The method of claim 1 , wherein the coupling of the first cable portion and the coupling of the second cable portion occur in a state when the drive shaft and the capstan are disengaged from each other.
3 . The method of claim 1 , wherein the independent rotation of the drive shaft relative to the capstan to draw the drive cable into tension is performed by rotating the drive shaft only.
4 . The method of claim 1 , wherein the independent rotation of the drive shaft relative to the capstan to draw the drive cable into tension is performed by rotating the capstan only.
5 . The method of claim 1 , wherein the independent rotation of the drive shaft relative to the capstan to draw the drive cable into tension is performed by rotating the capstan and the drive shaft.
6 . The method of claim 5 , wherein the independent rotation of the drive shaft relative to the capstan occurs by using a first motor and a second motor to respectively independently rotate each of the drive shaft and the capstan.
7 . The method of claim 5 , wherein the independent rotation of the drive shaft relative to the capstan comprises alternatively rotating the drive shaft and the capstan, with one of the drive shaft and the capstan being held fixed, while the other one of the drive shaft and the capstan is driven.
8 . The method of claim 5 , wherein the independent rotation of the drive shaft relative to the capstan comprises rotating the drive shaft and the capstan simultaneously.
9 . The method of claim 1 , wherein coupling the first cable portion of the drive cable to the drive shaft or the second cable portion of the drive cable to the capstan includes:
routing the drive cable through a plurality of bends of a tortuous path of the capstan,
winding the drive cable around a spool of the capstan, and
routing the drive cable along an outwardly facing helical groove.
10 . The method of claim 1 , wherein the securing the drive shaft and the capstan in a fixed rotational relationship with each other comprises using splined engagement features of the splined snap-fit connection mechanism.
11 . The method of claim 1 , further comprising securing the drive shaft and the capstan in a fixed axial relationship using snap-fit engagement features of the splined snap-fit connection mechanism.
12 . The method of claim 1 , wherein the drive cable is made of a polymer material.
13 . A surgical instrument, comprising:
an instrument shaft;
an end effector coupled to the instrument shaft; and
a drive assembly coupled to the instrument shaft, the drive assembly comprising:
a drive cable extending along the instrument shaft and operably coupled to the end effector,
a drive shaft receiving a first portion of the drive cable; and
a capstan receiving a second portion of the drive cable,
wherein the capstan and the drive shaft are transitionable between an engaged state with each other and a disengaged state with each other, and
wherein, in the engaged state, the capstan and the drive shaft are secured in a fixed rotational relationship with each other via a splined snap-fit connection mechanism.
14 . The surgical instrument of claim 13 , wherein the drive shaft and the capstan are secured in the fixed rotational relationship with each other by using splined engagement features of the splined snap-fit connection mechanism.
15 . The surgical instrument of claim 14 , wherein the splined engagement features of the splined snap-fit connection mechanism comprise a first plurality of splines projecting from a wall of a central bore of the capstan.
16 . The surgical instrument of claim 15 , wherein the splined engagement features of the splined snap-fit connection mechanism further comprise a second plurality of splines included in a cylindrical rod of the drive shaft.
17 . The surgical instrument of claim 16 , wherein the first plurality of splines are radially tapered along a longitudinal direction of the capstan.
18 . The surgical instrument of claim 17 , wherein the second plurality of splines are radially tapered in a direction opposite to the first plurality of splines.
19 . The surgical instrument of claim 13 , wherein, in the engaged state, the capstan and the drive shaft are secured in a fixed axial relationship using snap-fit engagement features of the splined snap-fit connection mechanism.
20 . The surgical instrument of claim 13 , wherein, in the disengaged state:
the drive shaft is coupled to a first cable portion of the drive cable,
the capstan is coupled to a second cable portion of the drive cable, and
the drive shaft is independently rotated relative to the capstan to draw the drive cable into tension.