DOUBLE UNIVERSAL JOINT
Surgical tools having a two degree-of-freedom wrist, wrist articulation by linked tension members, mechanisms for transmitting torque through an angle, and minimally invasive surgical tools incorporating these features are disclosed. An elongate intermediate wrist member is pivotally coupled with a distal end of an instrument shaft so as to rotate about a first axis transverse to the shaft, and an end effector body is pivotally coupled with the intermediate member so as to rotate about a second axis that is transverse to the first axis. Linked tension members interact with attachment features to articulate the wrist. A torque-transmitting mechanism includes a coupling member, coupling pins, a drive shaft, and a driven shaft. The drive shaft is coupled with the driven shaft so as to control the relative orientations of the drive shaft, the coupling member, and the driven shaft.
1 . A mechanism for transmitting torque through an angle, the mechanism comprising:
a coupling member comprising a first end and a second end with a coupling axis defined there between, the first end comprising a receptacle;
a coupling pin extending across the receptacle;
a drive shaft having a drive axis and a distal end received within the receptacle, the drive shaft distal end comprising a slot receiving the coupling pin throughout a range of angles between the coupling axis and the drive axis so that rotation of the drive shaft produces rotation of the coupling member via the coupling pin;
a driven shaft having a proximal end and a driven axis, the proximal end of the driven shaft coupled with the second end of the coupling member so that rotation of the coupling member about the coupling axis produces rotation of the driven shaft about the driven axis, the drive shaft coupled with the driven shaft so as to maintain corresponding angles between
the drive axis and the coupling axis, and
the driven axis and the coupling axis
when an angle between the drive axis and the driven axis varies during rotation of the shafts.
2 . The mechanism of claim 1 , further comprising a cross pin to couple the drive shaft with the coupling pin, the cross pin oriented transverse to the coupling pin and mounted for rotation relative to the drive shaft.
3 . The mechanism of claim 1 , wherein an outer surface of the drive shaft distal end comprises a spherical surface, and wherein the outer surface of the drive shaft interfaces with the receptacle of the coupling member so as to axially constrain the drive shaft and receptacle relative to each other during spherical pivoting there between.
4 . The mechanism of claim 3 , wherein the receptacle comprises a spherical surface interfacing with the drive shaft spherical surface.
5 . The mechanism of claim 1 , wherein:
the drive shaft distal end further comprises a set of spherical gear teeth;
the driven shaft proximal end comprises a set of spherical gear teeth interfacing with the drive shaft gear teeth so as to maintain the substantially equivalent angles between
the drive axis and the coupling axis, and
the driven axis and the coupling axis.
6 . The mechanism of claim 5 , wherein at least one of the drive shaft and the drive shaft gear teeth or the driven shaft and the driven shaft gear teeth are integrally formed.
7 . The mechanism of claim 1 , wherein the mechanism is operable to transmit torque through an angle exceeding 60 degrees.
8 . A mechanism for transmitting torque through an angle, the mechanism comprising:
a drive shaft having a distal end and a drive axis;
a driven shaft having a proximal end and a driven axis, wherein at least one of the drive shaft distal end or the driven shaft proximal end comprises a protrusion; and
a coupling member coupled with each of the drive shaft distal end and the driven shaft proximal end so that rotation of the drive shaft about the drive axis produces rotation of the driven shaft about the driven axis, the coupling member comprising a tubular structure defining a drive receptacle and a driven receptacle with a coupling axis defined there between, at least one of the drive receptacle or the driven receptacle comprising a slot configured to receive the at least one protrusion and accommodate the at least one protrusion through a range of angles between the drive shaft and the driven shaft, wherein the protrusion interacts with the slot so as to transfer rotational motion between the drive shaft and the driven shaft,
wherein the drive shaft distal end engages the driven shaft proximal end so as to maintain corresponding angles between
the drive axis and the coupling axis, and
the driven axis and the coupling axis
when an angle between the drive axis and the driven axis varies during rotation of the shafts.
9 . The mechanism of claim 8 , wherein each of the drive shaft distal end and the driven shaft proximal end comprises an outer surface interfacing with the drive receptacle and the driven receptacle, respectively, such that, for each shaft, an intersection point defined between the shaft axis and the coupling axis is axially affixed along the shaft axis and along the coupling axis.
10 . The mechanism of claim 9 , wherein each outer surface comprises a spherical surface.
11 . The mechanism of claim 10 , wherein each receptacle comprises a spherical surface.
12 . The mechanism of claim 8 , wherein the drive shaft distal end comprises a drive shaft gear tooth surface extending around the drive axis, wherein the driven shaft proximal end comprises a driven shaft gear tooth surface extending around the driven axis, and wherein the drive shaft gear tooth surface engages the driven shaft gear tooth surface so as maintain correspondence between the angles.
13 . The mechanism of claim 12 , wherein at least one of the drive shaft and the drive shaft gear tooth surface or the driven shaft and the driven shaft gear tooth surface are integrally formed.
14 . The mechanism of claim 12 , wherein the drive shaft gear tooth surface is defined by a drive shaft gear tooth profile extending radially from the drive axis, wherein the driven shaft gear tooth surface is defined by a driven shaft gear tooth profile extending radially from the driven axis, and wherein the drive shaft gear tooth surface engages the driven shaft gear tooth surface so as maintain substantial equivalence between the drive/coupler angle and the driven/coupler angle.
15 . The mechanism of claim 12 , wherein the drive shaft gear tooth surface comprises a revolute surface defined by rotating the drive shaft gear tooth profile about the drive axis, wherein the driven shaft gear tooth surface comprises a revolute surface defined by rotating the driven shaft gear tooth profile about the driven axis.
16 . The mechanism of claim 8 , wherein the mechanism is operable to transmit torque through an angle exceeding 60 degrees.
17 . A minimally invasive surgical tool comprising:
an instrument shaft;
a drive shaft having a distal end and a drive axis, the drive shaft being mounted for rotation within the instrument shaft;
a driven shaft having a proximal end and a driven axis;
a coupling member coupling the drive shaft with the driven shaft so that a rate of rotation of the drive and driven shafts are substantially equal when the drive axis and the driven axis are non-parallel; and
an end effector coupled with the instrument shaft so that an orientation of the end effector can be varied in two dimensions relative to the instrument shaft, the end effector comprising an articulated feature coupled with the driven shaft so that a rotation of the driven shaft about the driven axis produces an articulation of the feature.
18 . The tool of claim 17 , wherein:
the coupling member comprises a first end and a second end with a coupling axis defined there between;
the drive shaft distal end is axially and rotationally coupled with the coupling member first end so that rotation of the drive shaft about the drive axis produces rotation of the coupling member about the coupling axis; and
the driven shaft proximal end is axially and rotationally coupled with the coupling member second end so that rotation of the coupling member about the coupling axis produces rotation of the driven shaft about the driven axis,
wherein the drive shaft distal end engages the driven shaft proximal end so as to maintain corresponding angles between
the drive axis and the coupling axis, and
the driven axis and the coupling axis
when an angle between the drive axis and the driven axis varies during rotation of the shafts.
19 . The tool of claim 18 , wherein the drive shaft distal end comprises spherical gear teeth and the driven shaft proximal end comprises spherical gear teeth engaging the drive shaft gear teeth.
20 . The tool of claim 19 , wherein at least one of the drive shaft and the drive shaft gear teeth or the driven shaft and the driven shaft gear teeth are integrally formed.
21 . The tool of claim 18 , further comprising:
a coupling member first end receptacle;
a coupling pin crossing the receptacle;
a drive shaft distal end outer surface interfacing with the receptacle; and
a drive shaft distal end slot receiving the coupling pin throughout a range of angles between the coupling axis and the drive axis, wherein interaction between the coupling pin and the slot couples the drive shaft with the coupling member so that rotation of the drive shaft produces rotation of the coupling member.
22 . The tool of claim 21 , further comprising a cross pin to couple the drive shaft with the coupling pin, the cross pin oriented transverse to the coupling pin and mounted for rotation relative to the drive shaft.
23 . The tool of claim 18 , wherein:
at least one of the drive shaft distal end or the driven shaft proximal end comprises a protrusion;
the coupling member comprising a tubular structure defining a drive receptacle and a driven receptacle disposed along the coupling axis;
at least one of the drive receptacle or the driven receptacle comprises a slot configured to receive the protrusion and accommodate the protrusion through a range of angles between the drive axis and the driven axis; and
the protrusion interacts with the slot so as to transfer rotational motion between at least one of the drive shaft or the driven shaft and the coupling member.