Description:PLEASE SEE THE ATTACHMENTS. , Claims:1. A robotic surgical instrument comprising:
a shaft (504);
an end effector (501) comprising a first end effector element (502) and a
second end effector element (503);
an articulation (505) connecting the end effector (501) to the shaft (504), the
articulation (505) comprising:
a first joint (506) driveable by a first pair of driving elements (A1, A2),
the first joint permitting the end effector (501) to rotate about a first axis (510)
transverse to a longitudinal axis of the shaft (511);
a second joint (507) driveable by a second pair of driving elements (B1,
B2), the second joint permitting the first end effector element (502) to rotate
about a second axis (512) transverse to the first axis (510); and
a third joint (513) driveable by a third pair of driving elements (C1, C2),
the third joint permitting the second end effector element (503) to rotate
about the second axis (512);
the robotic surgical instrument further comprising a pulley arrangement
around which the second and third pairs of driving elements are constrained to move,
the pulley arrangement comprising:
a first set of pulleys (601) rotatable about the first axis (510); and
a second set of pulleys (602) configured to redirect the second and
third pairs of driving elements from the first set of pulleys into the shaft, the second
set of pulleys comprising a first pulley (701) and a second pulley (702) located on
opposing sides of the first joint in a longitudinal direction of the shaft, wherein each
pulley of the second set of pulleys (602) is rotatable about an axis parallel to the first
axis and offset from the first axis (510);
wherein the first pulley (701) of the second set of pulleys (602) is rotatable
about a third axis (703), and the second pulley (702) of the second set of pulleys (602)
is rotatable about a fourth axis (704), the third axis being offset from the fourth axis.
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2. A robotic surgical instrument as claimed in claim 1, wherein the first set of pulleys
(601) comprises a first pulley (705) and a second pulley (706) located on opposing
sides of the first joint (506) in a longitudinal direction of the shaft.
3. A robotic surgical instrument as claimed in claim 1 or 2, wherein in a straight
configuration of the robotic surgical instrument in which the end effector is aligned
with the shaft, the path of the second pair of driving elements around the pulley
arrangement is rotationally symmetrical about the longitudinal axis of the shaft to the
path of the third pair of driving elements around the pulley arrangement.
4. A robotic surgical instrument as claimed in claim 1 to 3, wherein the second and third
pairs of driving elements emerge from the pulley arrangement at a distal end of the
shaft in a symmetrical arrangement.
5. A robotic surgical instrument as claimed in claim 1, wherein a distal end of the shaft is
connected to the articulation, and a proximal end of the shaft is connected to a drive
mechanism for driving articulation of the end effector, the second and third pairs of
driving elements overlapping in the shaft so as to emerge at the drive mechanism with
the first one of the second pair of driving elements adjacent to the second one of the
second pair of driving elements, and with the first one of the third pair of driving
elements adjacent to the second one of the third pair of driving elements.
6. A robotic surgical instrument as claimed in claim 5, wherein the drive mechanism
comprises a further pulley arrangement around which the second and third pairs of
driving elements are constrained to move.
7. A robotic surgical instrument as claimed in claim 6, each of the second and third pairs
of driving elements extending from the pulley arrangement to the further pulley
arrangement without wrapping around any intervening pulleys.
8. A robotic surgical instrument as claimed in any preceding claim, wherein the second
set of pulleys is located inside the shaft.
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9. A robotic surgical instrument as claimed in any of claims 1 to 7, wherein the
articulation comprises the second set of pulleys.
10. A robotic surgical instrument as claimed in any preceding claim, the pulley
arrangement further comprising a pair of redirecting pulleys between the first set of
pulleys and the second joint, the pair of redirecting pulleys comprising:
a first redirecting pulley rotatable about a first redirecting pulley axis, the
second pair of driving elements being constrained to move around the first redirecting
pulley, the first redirecting pulley axis at an angle to the first axis so as to cause the
first redirecting pulley to redirect a first one of the second pair of driving elements
from a take-off point of a first pulley of the first set of pulleys to a pick-up point of the
second joint; and
a second redirecting pulley rotatable about a second redirecting pulley axis,
the third pair of driving elements being constrained to move around the second
redirecting pulley, the second redirecting pulley axis at an angle to the first axis so as
to cause the second redirecting pulley to redirect a first one of the third pair of driving
elements from a take-off point of a second pulley of the first set of pulleys to a pickup
point of the third joint.
11. A robotic surgical instrument as claimed in any preceding claim, wherein the second
pair of driving elements and the third pair of driving elements have the same length
for all rotation angles of the end effector element relative to the longitudinal axis of
the shaft.
12. A robotic surgical instrument as claimed in any preceding claim, wherein the second
and third pairs of driving elements have symmetrically opposing paths around the
pulley arrangement.