Note: Descriptions are shown in the official language in which they were submitted.
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PLATFORM LINK WRIST MECHANISM
This application is divided from Canadian Application Serial No. 2,792,000
which was divided
from Canadian Application Serial No. 2,451,824 filed on June 28, 2002.
ACKGROUND OF THE INVENTION
[14] The present invention relates generally to surgical tools and, more
particularly, to various
wrist mechanisms in surgical tools for performing robotic surgery.
[15] Robotic surgery has developed to improve and expand the use of minimally
invasive
surgical (MIS) techniques in the treatment of patients. Minimally invasive
techniques are aimed
at reducing the amount of extraneous tissue that is damaged during diagnostic
or surgical
procedures, thereby reducing patient recovery time, discomfort, and
deleterious side effects. The
average length of a hospital stay for a standard surgery may also be shortened
significantly using
MIS techniques. Thus, an increased adoption of minimally invasive techniques
could save
millions of hospital days and millions of dollars annually in hospital
residency costs alone.
Patient recovery times, patient discomfort, surgical side effects and time
away from work may
also be reduced with minimally invasive surgery.
[16] The most common form of minimally invasive surgery may be endoscopy. And,
probably
the most common form of endoscopy is laparoscopy, which is minimally invasive
inspection and
surgery inside the abdominal cavity. In standard laparoscopic surgery, a
patient's abdomen is
insufflated with gas, and cannula sleeves are passed though small
(approximately 1/2 inch)
incisions to provide entry ports for laparoscopic surgical instruments. The
laparoscopic surgical
instruments generally include a laparoscope (for viewing the surgical field)
and working tools.
The working tools are similar to those used in conventional (open) surgery,
except that the
working end or end effector of each tool is separated from its handle by an
extension tube. As
used herein, the term "end effector" means the actual working part of the
surgical instrument and
can include clamps, graspers, scissors, staplers, and needle holders, for
example. To perform
surgical procedures, the
surgeon passes these working tools or instruments though the cannula sleeves
to an internal
surgical site and manipulates them from outside the abdomen. The surgeon
monitors the
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procedure by means of a monitor that displays an image of the surgical site
taken from the
laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy,
retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy,
sinoscopy,
hysteroscopy, urethroscopy and the like.
[17] There are many disadvantages relating to current MIS technology. For
example, existing
MIS instruments deny the surgeon the flexibility of tool placement found in
open surgery. Most
current laparoscopic tools have rigid shafts, so that it can be difficult to
approach the worksite
through the small incision. Additionally, the length and construction of many
endoscopic
instruments reduces the surgeon's ability to feel forces exerted by tissues
and organs on the end
effector of the associated tool. The lack of dexterity and sensitivity of
endoscopic tools is a major
impediment to the expansion of minimally invasive surgery.
[18] Minimally invasive telesurgical robotic systems are being developed to
increase a
surgeon's dexterity when working within an internal surgical site, as well as
to allow a surgeon to
operate on a patient from a remote location. In a telesurgery system, the
surgeon is often
provided with an image of the surgical site at a computer workstation. While
viewing a three-
dimensional image of the surgical site on a suitable viewer or display, the
surgeon performs the
surgical procedures on the patient by manipulating master input or control
devices of the
workstation. The master controls the motion of a servomechanically operated
surgical
instrument. During the surgical procedure, the telesurgical system can provide
mechanical
actuation and control of a variety of surgical instruments or tools having end
effectors such as,
e.g. , tissue graspers, needle drivers, or the like, that perform various
functions for the surgeon, e.
g. , holding or driving a needle, grasping a blood vessel, or dissecting
tissue, or the like, in
response to manipulation of the master control devices.
[19] Manipulation and control of these end effectors is a critical aspect
of robotic surgical
systems. For these reasons, it is desirable to provide surgical tools which
include mechanisms to
provide three degrees of rotational movement of an end effector around three
perpendicular axes
to mimic the natural action of a surgeon's wrist. Such mechanisms should be
appropriately sized
for use in a minimally invasive procedure and relatively simple in design to
reduce possible
points of failure. In addition, such mechanisms should provide adequate degree
of rotation to
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allow the end effector to be manipulated in a wide variety of positions. At
least some of these
objectives will be met by the inventions described hereinafter.
BRIEF SUMMARY OF THE INVENTION
[20] The present invention provides a robotic surgical tool for use in a
robotic surgical system
to perform a surgical operation. Robotic surgical systems perform surgical
operations with tools
which are robotically operated by a surgeon. Such systems generally include
master controllers
and a robotic arm slave cart. The robotic arm slave cart is positioned
adjacent to the patient's
body and moves the tools to perform the surgery. The tools have shafts which
extend into an
internal surgical site within the patient body via minimally invasive access
openings. The robotic
arm slave cart is connected with master controllers which are grasped by the
surgeon and
manipulated in space while the surgeon views the procedure on a stereo
display. The master
controllers are manual input devices which preferably move with six degrees of
freedom, and
which often further have an actuatable handle for actuating the tools (for
example, for closing
grasping saws, applying an electrical potential to an electrode, or the like).
Robotic surgery
systems and methods are further described in U.S. Patent No. 6,132,369 filed
November 21,
1997.
[21] As described, robotic surgical tools comprise an elongated shaft having a
surgical end
effector disposed near the distal end of the shaft. As used herein, the terms
"surgical instrument",
"instrument", "surgical tool", or "tool" refer to a member having a working
end which carries
one or more end effectors to be introduced into a surgical site in a cavity of
a patient, and is
actuatable from outside the cavity to manipulate the end effector(s) for
effecting a desired
treatment or medical function of a target tissue in the surgical site. The
instrument or tool
typically includes a shaft carrying the end effector(s) at a distal end, and
is preferably
servomechanically actuated by a telesurgical system for performing functions
such as holding or
driving a needle, grasping a blood vessel, and dissecting tissue. In addition,
as used herein, "end
effector" refers to the actual working part that is manipulable for effecting
a predetermined
treatment of a target tissue. For instance, some end effectors have a single
working member such
as a scalpel, a blade, or an electrode. Other end effectors have a pair or
plurality of working
members such as forceps, graspers, scissors, or clip appliers, for example.
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[21A] In a first aspect, there is described a robotic surgical tool
comprising: a distal member
configured to support an end effector; first and second components constrained
to move in
tandem and in opposite directions generally in parallel to an axial line and
rotatably coupled to
the distal member so that an advancement of die first component with a
corresponding retraction
of the second component causes the distal member to face a first articulated
direction defining a
first angle with respect to the axial line, and an advancement of the second
component with a
corresponding retraction of the first component causes the distal member to
face a second
articulated direction defining a second angle with respect to the axial line;
and third and fourth
components constrained to move in tandem and in opposite directions generally
in parallel to the
axial line, and rotatably coupled to the distal member so that an advancement
of the third
component with a corresponding retraction of the fourth component causes the
distal member to
face a third articulated direction defining a third angle with respect to the
axial line.
[21B] In a further aspect, there is described a method of configuring a
robotic surgical tool
comprising: constraining first and second components to move in tandem and in
opposite
directions generally in parallel to an axial line so that movement of the
first component in a first
direction with corresponding movement of the second component in an opposite
direction causes
a distal member supporting an end effector to be oriented at a first angle
with respect to the axial
line, wherein the constraining of the first and second components to move in
tandem and in
opposite directions comprises providing a first rotational actuation member to
which the first and
second components are coupled on opposing sides so as to cause the first
component to move in
the first direction and the second component to move in an opposite direction
when rotated in a
first rotary direction.
[21C] In a further aspect, there is described a robotic surgical tool
comprising: a distal member
configured to support an end effector; a plurality of rods mechanically
coupled to the distal
member and movable generally along an axial direction to adjust an orientation
of the distal
member with respect to the axial direction; and a tool base including a first
rotational actuation
mechanism mechanically coupled to at least one of the plurality of rods so as
to control
movement of the at least one rod generally along the axial direction, and a
roll actuation
mechanism mechanically coupled to the distal member to control rotation of the
distal member
about the axial direction, wherein first and second rods of the plurality of
rods are coupled to the
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first rotational actuation mechanism so that rotation of the first rotational
actuation mechanism in
a first direction causes advancement of the first rod and retraction of the
second rod, the first
rotational actuation mechanism includes a first sector gear and a first
pitch/yaw gear, the first
sector gear having an axis of rotation and two pivot pins positioned on
opposite sides of the axis
5 of rotation, the first and second rods are respectively connected to the
two pivot pins so as to
advance and retract the first and second rods when the first sector gear is
rotated about the axis of
rotation, the first pitch/yaw gear engaged with the first sector gear so as to
controllably rotate the
first sector gear.
[22] The robotic surgical tool may include a wrist mechanism disposed near the
distal end of
the shaft which connects with the end effector. The wrist mechanism includes a
distal member,
configured to support the end effector, and a plurality of rods extending
generally along an axial
direction within the shaft and movable generally along this axial direction to
adjust the
orientation of the distal member with respect to the axial direction or shaft.
The distal member
may have any form suitable for supporting an end effector. In most
embodiments, the distal
member has the form of a clevis. In any case, the distal member has a base to
which the rods are
rotatably connected.
[23] Advancement or retraction of a first rod generally along the axial
direction tips the base
though a first angle so that the distal member faces a first articulated
direction. The first angle
may be any angle in the range of 0-90 degrees and oriented so that the first
articulated direction
is any direction that is not parallel to the axial direction. This would allow
the distal member to
direct an end effector in any direction in relation to the shaft of the
surgical tool. In most
embodiments, the first angle is greater than approximately 30 degrees. In some
embodiments, the
first angle is greater than approximately 60 degrees and in other embodiments
the first angle is
greater than approximately 70 degrees. This first angle may represent the
pitch or the yaw of the
wrist mechanism.
[24] In some embodiments, advancement or retraction of a second rod generally
along the
axial direction tips the base through a second angle so that the distal member
faces a second
articulated direction. The second angle may also be any angle in the range of
0-90 degrees and
oriented so that the second articulated direction is any direction that is not
parallel to the axial
direction. The addition of a second angle would allow the distal member to
direct an end effector
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in essentially a compound angle or in a second articulated direction in
relation to the shaft of the
surgical tool. In most embodiments, the second angle is greater than
approximately 30 degrees.
In some embodiments, the second angle is greater than approximately 60 degrees
and in other
embodiments the second angle is greater than approximately 70 degrees. If the
first angle
represents the pitch of the wrist mechanism, the second angle may represent
the yaw of the wrist
mechanism and vice versa.
[25] The plurality of rods may comprise two, three, four or more rods. In
preferred
embodiments, three or four rods are used to provide both pitch and yaw
angulation. When four
rods are used, the first and second rods are positioned adjacent to each other
and the remaining
two rods are located in positions diametrically opposite to the first and
second rods. The four
rods are generally arranged symmetrically around a central axis of the shaft
or the axial direction.
When the first rod is advanced, the diametrically opposite rod is
simultaneously retracted.
Likewise, when the first rod is retracted, the diametrically opposite rod is
simultaneously
advanced. This is similarly the case with the second rod and its diametrically
opposite rod. Thus,
the rods actuate in pairs. Such actuation will be further described in a later
section.
[26] To maintain desired positioning of the rods, some embodiments include a
guide tube
having a plurality of guide slots. Each guide slot is shaped for receiving and
guiding one of the
plurality of rods substantially along the axial direction. In some
embodiments, the rods are
shaped so as to have a rectangular cross-section. In these instances, the
corresponding guide slots
also rectangular in shape to receive and maintain proper orientation of the
rods.
[27] The robotic surgical tool may include a tool base disposed near the
proximal end of the
shaft. The tool base includes mechanisms for actuating the wrist mechanism and
often
mechanisms for actuating the end effector. Mechanisms for actuating the wrist
mechanism
includes mechanisms for advancing or retracting the first rod. In some
embodiments, such
mechanisms comprises a first rotational actuation member to which the first
rod is attached so
that rotation of the first rotational actuation member advances or retracts
the first rod. Typically,
another rod is attached to the first rotational actuation member in a position
diametrically
opposite to the first rod so that rotation of the first rotational actuation
member simultaneously
advances the first rod and retracts the diametrically opposite rod. In some
embodiments, the tool
base further comprises a second rotational actuation member to which the
second rod is attached
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so that rotation of the second rotational actuation member advances or
retracts the second rod
substantially along the axial direction. Again, another rod is often attached
to the second
rotational actuation member in a position diametrically opposite to the second
rod so that rotation
of the second rotational actuation member simultaneously advances the second
rod and retracts
the diametrically opposite rod. Thus, by rotating the first and second
rotational actuation
members, the distal member is tipped through two angles, or a compound angle,
so that the distal
member faces any desired direction. This allows refined control of the end
effector throughout
three dimensions.
[28] The robotic surgical tool of the present invention may also include
provisions for roll
movement. Roll movement is achieved by rotating the shaft around its central
axis. Since the
shaft is connected to a guide tube through which the plurality of rods pass,
rotation of the shaft
rotates guide tube which in turn rotates the rods around the central axis
which is parallel to the
axial direction. To actuate such roll, the above described tool base comprises
a roll pulley which
rotates the shaft. Since the rods extend through the roll pulley and attach to
the rotational
actuation members, such rotation is possible by flexing of the rods. Due to
the length, thickness
and flexibility of the rods, 360 degree rotation is possible. Thus, pitch, yaw
and roll movement
can be individually actuated by the tool base, particularly by manipulation of
the rotational
actuation members and roll pulley.
[29] Although actuation of the wrist mechanism is achieved by manipulation of
the rods, it is
the connection of the rods to the base which allows tipping and manipulation
of the distal
member to face a desired direction. Such connection is achieved with the use
of a plurality of
linkages, each linkage connecting one of the plurality of rods with the base.
In some
embodiments, the linkages comprise orthogonal linkage assemblies. Each
orthogonal linkage
assembly rotatably connects one of the plurality of rods with the base to
allow the base to be
rotated in at least two directions with respect to the axial direction. In
some embodiments, each
orthogonal linkage assembly comprises an orthogonal linkage having a first
link portion which is
rotatably connectable with the one of the plurality of rods and a second link
portion which is
rotatably connectable with the base and wherein the first link portion and the
second link portion
lie in orthogonal planes. In other embodiments, each orthogonal linkage
assembly comprises a
linkage fastener having a link base portion which is rotatably connectable
with one of the
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plurality of rods and a cylindrical fastening end portion which is rotatably
connectable with the
base. The different orthogonal linkage assemblies allow the base to be rotated
to different
degrees of angularity relative to the axial direction.
[30] Such rotation is assisted by flexibility of the rods. Generally, each
rod is flexible in at
least one direction. For example, when each rod has a rectangular cross-
section, having a wide
side and a narrow side, the rod may be flexible along the wide side yet rigid
along the narrow
side. When the rods are arranged so that the wide sides are parallel to the
perimeter of the shaft,
flexibility along the wide sides allows each rod to bend slightly inward,
toward the center of the
shaft or the longitudinal axis. This allows greater rotation of the distal
member and flexibility in
design parameters.
[31] Methods of actuating the robotic surgical tool are described. In some
aspects, methods
include providing a robotic surgical tool comprising a wrist mechanism, which
includes a distal
member coupleable with a surgical end effector and having a base and a
plurality of rods
rotatably connected to the base and extending along an axial direction, and
actuating the wrist by
manipulating a first rod of the plurality of rods to tip the base through a
first angle so that the
distal member faces a first articulated direction. Manipulating typically
comprises advancing or
retracting the first rod. As previously mentioned, advancing or retracting may
comprise rotating
a first rotational actuation member to which the first rod is attached.
Likewise, actuating the
wrist may further comprises manipulating a second rod of the plurality of rods
to tip the base
through a second angle so that the distal member faces a second articulated
direction. Again,
advancing or retracting may comprise rotating a second rotational actuation
member to which the
second rod is attached.
[32] Methods further comprise actuating the wrist by rotating the plurality of
rods around a
longitudinal axis parallel to the axial direction to rotate the base. In some
embodiments, rotating
the plurality of rods comprises rotating a roll pulley though which the
plurality of rods extend.
And, lastly, methods may further comprise coupling the end effector to the
base and actuating
the end effector.
[33] Other features and advantages of the present invention will become
apparent from the
detailed description to follow, together with the accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
[34] Fig. 1 is a perspective overall view of an embodiment of the surgical
tool of the present
invention.
1351 Figs. 2A-2B illustrate exemplary surgical end effectors.
[36] Fig. 3 illustrates an embodiment of a wrist mechanism.
[37] Figs. 3A-3B illustrate possible arrangements of guide slots within the
guide tube.
[38] Figs. 3C-3D illustrate connection of rods to the distal member via
orthogonal linkages.
[39] Fig. 4 illustrates movement of the wrist mechanism through a compound
angle.
[40] Fig. 5 illustrates tipping in a variety of directions including a
combinations of pitch and
yaw.
[41] Figs. 6A-6F illustrate three different embodiments of the wrist mechanism
of the present
invention.
[42] Fig. 7 illustrates assemblage of the first main embodiment of the wrist
mechanism.
[43] Figs. 8-9 illustrate joining of a rod with an orthogonal linkage and then
joining of the
linkage with a foot on the distal clevis.
[44] Fig. 10 illustrates joining of additional rods to the distal clevis.
[45] Fig. 11A illustrates the first main embodiment of the wrist mechanism
wherein four rods
are attached. Fig. 11B is a cross-sectional view of Fig. 11A.
[46] Fig. 12 illustrates assemblage of the second main embodiment of the wrist
mechanism.
[47] Fig. 13 illustrates joining of a rod with a linkage fastened and for
later joining with a
distal clevis half.
[48] Fig. 14 illustrates joining rods with corresponding apertures on the
first and second clevis
halves with the use of linkage fasteners.
[49] Figs. 15-16 show mating of the clevis halves and joining with a clevis
tip.
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[50] Fig. 17A illustrates the second main embodiment of the wrist mechanism
wherein four rods are attached. Fig. 17B is a cross-sectional view of Fig.
17A.
[51] Fig. 18 is a perspective view of an embodiment of the wrist mechanism
showing rods inserted through a guide tube.
[52] Fig. 19 illustrates tipping of the distal clevis in response to
advancement
and/or retraction of one or more rods.
[53] Fig. 20 illustrates assemblage of the third main embodiment of the
wrist
mechanism.
[54] Figs. 21-22 illustrate joining of a rod with an linkage fastener and
then joining
linkage fastener with a foot on the distal clevis.
[55] Fig. 23A illustrates the third main embodiment of the wrist mechanism
wherein four rods are attached. Fig. 23B is a cross-sectional view of Fig.
23A.
[561 Fig. 24 illustrates tipping of the distal clevis in response to
advancement
and/or retraction of one or more rods.
157] Fig. 25 illustrates joining of a rod with a wire to create a wire/rod
assembly.
[58] Fig. 26 illustrates inserting the wire/rod assembly through a roll
pulley within
the tool base.
[59] Fig. 27 illustrates additional features of the tool base, including
rotational
actuation members.
[60] Fig. 28 is a side view illustrating insertion of the wire through a
crosshole in a
pivot pin which is mounted in a sector gear.
[61] Fig. 29 is a side view illustrating crimping of a crimp onto the wire
to maintain
positioning of the rod against the pivot pin.
[62] Fig. 30 is a top perspective view of the tool base, including
mechanisms to
manipulate the rods to actuate the wrist mechanism.
DETAILED DESCRIPTION OF THE INVENTION
[63] Fig. 1 illustrates a surgical tool 50 of the present invention which
is used in
robotic surgery systems. The surgical tool 50 includes a rigid shaft 52 having
a proximal end
54, a distal end 56 and a longitudinal axis therebetween. The proximal end 54
is coupled to a
tool base 62. The tool base 62 includes an interface 64 which mechanically and
electrically
couples the tool 50 to a manipulator on the robotic arm cart. A distal member,
in this
embodiment a distal clevis 58, is coupled to shaft 52 by a wrist joint or
wrist mechanism 10,
the wrist mechanism 10 providing the distal clevis 58 with at least 1 degree
of freedom and
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ideally providing at least 3 degrees of freedom. The distal clevis 58 supports
a surgical end
effector 66, the actual working part that is manipulable for effecting a
predetermined
treatment of a target tissue. Exemplary surgical end effectors 66 are
illustrated in Figs. 2A-
2B. Grasping jaws 70 are illustrated in Fig. 2A, while a cautery isolation
effector 72 is
5 illustrated in Fig. 2B. It may be appreciated however that any suitable
end effector 66 may
be used, such as DeBakey forceps, microforceps, Potts scissors, clip appliers,
scalpels or
electrocautery probes, to name a few. The end effectors 66 can be permanently
attached or
be removable and optionally replaceable with a different type of end effector
66 depending
on the surgical need.
10 [64] The end effector 66 is manipulated by the wrist mechanism 10
to provide the
ability of continuous movement in a wide range of angles (in roll, pitch and
yaw) relative to
an axial direction or the longitudinal axis 51 of the shaft 52. An embodiment
of the wrist
mechanism 10 is illustrated in Figs. 3, 3A-3D. Referring to Fig. 3, the wrist
joint or
mechanism 10 comprises a distal member 12 connected with a plurality of rods
14 via a
plurality of orthogonal linkages 16. Movement of the distal member 12 is
directly translated
to the surgical end effector 66. In this embodiment, the distal member 12 has
the shape of a
disk and includes a plurality of feet 18 with apertures 17 which are connected
to the
orthogonal linkages 16. There are at least three rods, and more desirably four
rods 14 as
shown in Fig. 3. The rods 14 extend through a guide tube 20 within the shaft
52 (not shown
in Fig. 3) which guides and supports the rods 14. Fig. 3A shows the guide tube
20 having
four guide slots 30 for receiving the four rods 14. Fig. 3B shows a guide tube
20' having
three guide slots 30' for receiving three rods in a different embodiment. The
guide slots 30 or
30' are evenly distributed in a generally circular pattern to allow the rods
14 to manipulate
and orient the distal member 12 in different directions in a generally
continuous manner.
[65] As the rods 14 are slid up and down the guide slots 30 of the guide
tube 20,
the orthogonal linkages 16 transfer the motion to the distal member 12. The
rods 14 are
configured to flex in one plane and be stiff in another plane. In the
embodiment shown, the
rods 14 are flattened to have a rectangular cross-section with a wide face and
a narrow width.
The rods 14 can flex along the wide face and remain stiff along the narrow
width. Referring
to Figs. 3A-3B, the rods 14 can flex toward or away from the center or central
axis of the
guide tube 20, 20' but remain stiff in terms of side-to-side movement along
the perimeter of
the guide tube 20, 20'.
[66] The rods 14 include apertures 19 near their distal ends which
connect the rods
14 to the distal member 12 via orthogonal linkages 16. Each orthogonal linkage
16 has a first
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link portion 22 and a second link portion 24 which are oriented in an
orthogonal manner, as
illustrated in Figs. 3C-3D. The first link portion 22 includes a first
aperture and the second
link portion 24 includes a second aperture which is perpendicular in
orientation with respect
to the first aperture. The second link portion 24 is rotatably coupled to the
distal end of the
rod 14 by a fastener 26 extending through the apertures of the second link
portion 24 and the
distal end of the rod 14. The first link portion 22 is rotatably coupled to
the feet 18 of the
distal member 12 by a fastener 28 extending through the apertures of the first
link portion 22
and the feet 18. Because each orthogonal linkage 16 allows relative movement
between the
rod 14 and the distal member 12 in two orthogonal directions, the distal
member 12 can be
articulated to move continuously to have orientation in a wide range of angles
(in roll, pitch,
and yaw) relative to the axial direction of the guide tube 20.
[67] When a first rod is extended generally along the axial direction, the
distal
member or clevis will be tipped through a first angle. Likewise, when a second
rod is
extended generally along the axial direction, the distal member or clevis will
be tipped
through a second angle creating a compound angle. An example of this movement
is shown
in a simplified illustration in Fig. 4. Here, distal clevis 58 is shown in
dashed line having
been tipped through a first angle 39 so that the clevis 58 faces a first
articulated direction 41.
For clarity, the axial direction 37 is aligned with the y-axis and the first
articulated direction
41 aligned with the z-axis so that the first angle 39 is formed in a y-z
plane. The distal clevis
58 is then tipped through a second angle 43 so that the clevis 58 faces a
second articulated
direction 45. The second angle 43 is formed in an x-z plane. In this
illustration, the first
angle 39 represents the pitch and the second angle 43 represents the yaw.
[68] Generally, the range of angles through which the distal member 12 can
be
articulated varies depending on the combination of pitch and yaw movement. For
example,
Fig. 5 illustrates a top view of the distal member 12 showing a first rod
connection point 500,
a second rod connection point 502, a third rod connection point 504 and a
fourth rod
connection point 506. In this example, a movement of pure pitch would involve
rotating the
distal member 12 around the y-axis or tipping the distal member toward the x
direction or -x
direction. This is achieved by advancement of a second rod and corresponding
second rod
connection point 502 and retraction of a fourth rod and corresponding fourth
rod connection
point 506, or vice versa. Likewise, in this example, a movement of pure yaw
would involve
rotating the distal member 12 around the x-axis or tipping the distal member
toward the y
direction or -y direction. This is achieved by advancement of a first rod and
corresponding
first rod connection point 500 and retraction of a third rod and corresponding
third rod
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12
connection point 504, or vice versa. In pure pitch or pure yaw, the distal
member 12 can be
tipped through angles up to approximately 90 degrees.
[69] However, when the distal member 12 is oriented to face a direction
between
pure pitch and pure yaw, additional challenges arise in achieving full
rotation. In particular,
the most challenging position occurs when tipping the distal member toward an
m direction
midway between the x direction and the y direction which would involve
approximately
equal portions of pitch and yaw. This would similarly be the case for tipping
toward an m',
m" or m" direction as shown in Fig. 5. In these positions, different
variations in the wrist
mechanism 10 design allow movement of the distal member through different
ranges of
angles. For example, three different embodiments of the wrist mechanism 10 are
shown in
Figs. 6A-6F wherein each wrist mechanism 10 design provides a different range
of motion in
this most challenging position. Fig. 6A is an illustration of a first main
embodiment of the
wrist mechanism 10 which allows movement in the approximate range of + 40
degrees, as
illustrated in corresponding Fig. 6B. In Fig. 6B, a plurality of rods are
shown wherein a first
rod and a second rod are extended generally along an axial direction 37 which
tips the clevis
58 through a combination of a first angle and a second angle (forming a
compound angle 39)
so that the clevis 58 faces an articulated direction 41. In this example, the
angle 39 is
approximately 39.2 degrees. This wrist mechanism embodiment was introduced
above and
will be further described herein below. Fig. 6C is an illustration of a second
main
embodiment of the wrist mechanism 10 which allows movement in the approximate
range of
+ 64 degrees, as illustrated in corresponding Fig. 6D. Again, a plurality of
rods are shown
wherein a first rod and a second rod are extended generally along an axial
direction 37 which
tips the clevis 58 through a first angle and a second angle (forming a
compound angle 39) so
that the clevis 58 faces a articulated direction 41. In this example, the
angle 39 is
approximately 63.5 degrees. Fig. 6E is an illustration of a third main
embodiment of the
wrist mechanism 10 which allows movement in the approximate range of + 74
degrees, as
illustrated in corresponding Fig. 6F. Likewise, a plurality of rods are shown
wherein a first
rod and a second rod are extended generally along an axial direction 37 which
tips the clevis
58 through a first angle and a second angle (forming a compound angle 39) so
that the clevis
58 faces a articulated direction 41. In this example, the angle 39 is
approximately 73.7
degrees.
[70] The three different main embodiments of Figs. 6A-6F will now be more
fully
described and illustrated. The wrist mechanism 10 of the first main embodiment
is illustrated
in Figs. 7-10, 11A-11B, 12, 13 and provides motion in the approximate range of
+ 40
CA 02927478 2016-04-15
13
degrees, under the conditions described above. Referring to Fig. 7, the distal
member is in
the form of a distal clevis 58 which has a plurality of feet 18 with apertures
17. In this view,
two feet 18 are visible, however four feet 18 are present in this embodiment
positioned
symmetrically around a base 59 of the distal clevis 58, as partially shown.
Each rod 14 is
connected with one of the feet 18 by an orthogonal linkage assembly. In this
embodiment,
the orthogonal linkage assembly comprises an orthogonal linkage 16 which has a
first link
portion 22 with a first aperture 23 and a second link portion 24 with a second
aperture 25,
wherein the first link portion 22 and second link portion 24 lie in
perpendicular planes.
Consequently, the apertures 23, 25 face directions which are 90 degrees apart.
A rod 14 is
connected to the second link portion 24 by inserting fastener 26 through
second aperture 25
and through aperture 19 located near the distal end 15 of the rod 14. As
shown, aperture 19
passes through the wide side 14a of the rod 14. The fastener 26 may be of any
suitable type,
for example the fastener 26 may include a head 27 and a body 29 as shown. In
this case, the
body 29 is inserted through the appropriate apertures. Once inserted, the
fastener 26 is then
held in place by altering the body 29, such as by swaging, to create a flange,
lip, hook or
crimp. Thus, the second link portion 24 and distal end 15 of the rod 14 may be
held together
between the head 27 and the swaged end of the body 29. This allows free
rotation of the rod
14 in the plane of the second link portion 24. Such joining of the second link
portion 24 and
distal end 15 of the rod 14 is illustrated in Fig. 8.
[71] Similarly, the first link portion 22 is connected with one of the feet
18 by
inserting fastener 28 through aperture 17 of foot 18 and through first
aperture 23 of the first
link portion 22. Again, once inserted, fastener 28 can be held in place by
altering the body
29, such as by swaging. Thus, the first link portion 22 and foot 18 may be
held together
between the head 27 and the swaged end of the body 29. This allows free
rotation of the first
link portion 22 in the plane of the foot 18. Such joining of the first link
portion 22 and foot
18 is illustrated in Fig. 9. Due to the shape of the orthogonal linkage 16 and
the
perpendicular orientation of the apertures 23, 25, the foot 18 is able to be
translated in the
plane of second link portion 24 or wide side 14a of the rod 14, offset from
aperture 19, while
being rotated in a plane perpendicular to the plane of second link portion 24,
or parallel to the
narrow side 14b of the rod 14. Consequently, the distal clevis 58 attached to
the foot 18 may
be tipped to various degrees along two axes simultaneously.
(72] As shown in Fig. 10, each of the four rods 14 are connected with
a
corresponding foot 18 as described above. Fig. 11 A illustrates the wrist
mechanism 10
wherein all four rods 14 are attached to the feet 18 of the distal clevis 58.
Fig. 118 is a cross-
CA 02927478 2016-04-15
14
sectional view of Fig. 11A. When four rods 14 are present, advancement of one
rod tips the
distal clevis 58 to face away from the advanced rod. In some embodiments, this
simultaneously retracts the rod attached to the distal clevis 58 in the
diametrically opposite
position. When a rod adjacent to the advanced rod is advanced, the distal
clevis 58 is tipped
to face away from the newly advanced rod simultaneously retracting the
diametrically
opposite rod. By varying which rods are advanced and the amount by which they
are
advanced, the distal clevis can be tipped through a continuous series of
angles.
[73] The wrist mechanism 110 of the second main embodiment is illustrated
in
Figs. 12-16, 17A-17B, 18, 19, and provides motion in the approximate range f
64 degrees,
under the conditions described above. In this embodiment, the distal clevis
158 is comprised
of a first clevis half 102 and a second clevis half 104 which are then mated
by a clevis mater
106 and joined with a clevis tip 108. This arrangement allows ease of
assembly, reduction of
parts and an increased range of motion.
[74] Referring to Fig. 12, the first clevis half 102 is illustrated. Rather
than having
feet as in the first main embodiment, apertures 117 are formed directly in the
first clevis half
102. The rod 114 is then attached to the first clevis half 102 with the use of
linkage fastener
116. The linkage fastener 116 comprises a link base portion 124 with an
aperture 125 and a
fastening end portion 128 which extends in the same plane as the link base
portion 124. A
rod 114 is connected to the link base portion 124 by inserting fastener 126
through aperture
125 and through aperture 119 located near the distal end 115 of the rod 114.
As shown,
aperture 119 passes through the narrow side 114b of the rod 114. The fastener
126 may be of
any suitable type, for example the fastener 126 is shown to include a head 127
and a body
129. In this case, the body 129 is inserted through the appropriate apertures.
Once inserted,
the fastener 126 is then held in place by altering the body 129, such as by
swaging, to create a
flange, lip, hook or crimp. Thus, the link base portion 124 and distal end 115
of the rod 114
may be held together between the head 127 and the swaged end of the body 129.
This allows
free rotation of the rod 114 in the plane of the link base portion 124. Such
joining of the link
base portion 124 and distal end 115 of the rod 114 is illustrated in Fig. 13.
[75] The linkage fastener 116 is then connected with first clevis half 102
by
inserting fastening end portion 128 through aperture 117. Once inserted, the
linkage fastener
116 can be held in place by altering the fastening end portion 128, such as by
swaging, to
create a flange, lip, hook or crimp on the inside of the first clevis half
102. Thus, the first
clevis half 102 may be held between the link base portion 124 and the swaged
end of the
fastening end portion 128. This allows free rotation of the first clevis half
102 in the plane
CA 02927478 2016-04-15
perpendicular to the link base portion 124. Due to the shape of the linkage
fastener 116 and
the orientation of the apertures 119. 125, 117, the first clevis half 102 is
able to be translated
in the plane of link base portion 124 or narrow side 114b of the rod 114,
offset from aperture
119, while being rotated in a plane perpendicular to the plane of link base
portion 124, or
5 parallel to the wide side 114a of the rod 114. Consequently, the first
clevis half 102 attached
may be tipped to various degrees along two axes simultaneously.
[76] As shown in Fig. 14, rods 114 are connected with corresponding
apertures 119
on the first clevis half 102 and the second clevis half 104 with the use of
linkage fasteners
116 as described above. In this embodiment, two rods 114 are attached to each
half 102, 104
10 for a total of four symmetrically placed rods. Again, it may be
appreciated that any number
of rods 114 may be used and attached to the clevis halves 102, 103 in any
arrangement. As
shown in Fig. 15, the clevis halves 102, 103 are then mated by insertion into
the clevis mater
106. The clevis mater 106 may be a ring, as shown, wherein the halves 102, 103
are press fit
within. Referring now to Fig. 16, the clevis mater 106 is then joined with the
clevis tip 108,
15 typically by a threaded fit or press fit.
[77] Fig. 17A illustrates the wrist mechanism 110 wherein all four rods 114
are
attached to distal clevis 158. Fig. 17B is a cross-sectional view of Fig. 17A.
Fig. 18 provides
a perspective view of the wrist mechanism 110 showing the rods 114 inserted
through guide
tube 120 in shaft 152 of the tool 50. The guide tube 120 includes guide slots
121 through
which the rods 114 pass to hold rods 114 in the desired orientation.
Advancement (indicated
by arrow 130) of one rod 114' tips the distal clevis 158 to face away from the
advanced rod
114', as illustrated in Fig. 19. In some embodiments, this simultaneously
retracts the rod
114" attached to the distal clevis 158 in the diametrically opposite position.
When a rod
adjacent to the advanced rod is advanced, the distal clevis 158 is tipped to
face away from the
newly advanced rod simultaneously retracting the diametrically opposite rod.
By varying
which rods are advanced and the amount by which they are advanced, the distal
clevis can be
tipped through a continuous series of angles.
[78] The wrist mechanism 210 of the third main embodiment is illustrated in
Figs.
20-22, 23A-23B, 24, and provides motion in the approximate range of + 74
degrees, under
the conditions described above. Referring to Fig. 20, the distal member is in
the form of a
distal clevis 258, which has a plurality of feet 218 with apertures 217 and a
clevis tip 208. In
this view, three feet 218 are visible, however four feet 218 are present in
this embodiment
positioned symmetrically around a base 259 of the distal clevis 258, as
partially shown. Each
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rod 214 is connected with one of the feet 218 by an linkage fastener 216. This
arrangement
allows ease of assembly, reduction of parts and an increased range of motion.
[79] The linkage fastener 216 comprises a link base portion 224 with
an aperture
225 and a fastening end portion 228 which extends in the same plane as the
link base portion
224. A rod 214 is connected to the link base portion 224 by inserting fastener
226 through
aperture 219, located near the distal end 215 of the rod 214 and passes
through the wide side
214b of the rod 214, and through aperture 225. The fastener 226 may be of any
suitable type,
for example the fastener 226 is shown to include a head 227 and a body 229. In
this case, the
body 229 is inserted through the appropriate apertures. Once inserted, the
fastener 226 is
then held in place by altering the body 229, such as by swaging, to create a
flange, lip, hook
or crimp. Thus, the link base portion 224 and distal end 215 of the rod 214
may be held
together between the head 227 and the swaged end of the body 229. This allows
free rotation
of the rod 214 in the plane of the link base portion 224. Such joining of the
link base portion
224 and distal end 215 of the rod 214 is illustrated in Fig. 21.
[80] The linkage fastener 216 is then connected with the distal clevis 258
by
inserting fastening end portion 228 through aperture 117, as illustrated in
Fig. 22. Once
inserted, the linkage fastener 216 can be held in place by altering the
fastening end portion
228, such as by swaging. Thus, the foot 218 may be held between the link base
portion 224
and the swaged end of the fastening end portion 228. This allows free rotation
of the foot
218 in the plane perpendicular to the link base portion 224. Due to the shape
of the linkage
fastener 216 and the orientation of the apertures 219, 225, 217, the foot 218
is able to be
translated in the plane of the link base portion 224 or wide side 214a of the
rod 214, offset
from aperture 219, while being rotated in a plane perpendicular to the plane
of link base
portion 224, or parallel to the narrow side 214b of the rod 214. Consequently,
the attached
distal clevis 258 may be tipped to various degrees along two axes
simultaneously.
[81] Fig. 23A illustrates the wrist mechanism 210 wherein all four
rods 214 are
attached to distal clevis 258. Fig. 23B is a cross-sectional view of Fig. 23A.
Fig. 24 provides
a perspective view of the wrist mechanism 210. Advancement (indicated by arrow
230) of
one rod 214' tips the distal clevis 258 to face away from the advanced rod
214'. In some
embodiments, this simultaneously retracts the rod 214" attached to the distal
clevis 258 in the
diametrically opposite position. When a rod adjacent to the advanced rod is
advanced, the
distal clevis 258 is tipped to face away from the newly advanced rod
simultaneously
retracting the diametrically opposite rod. By varying which rods are advanced
and the
CA 02927478 2016-04-15
17
amount by which they are advanced, the distal clevis can be tipped through a
continuous
series of angles.
[82] Actuation of any of the wrist mechanism embodiments described above is
achieved with the use of the tool base 62 schematically depicted in Fig. 1. As
shown, the
proximal end 54 of the shaft 52 is coupled to the tool base 62. Rods extend
through the shaft
52 from the wrist mechanism 10 to the tool base 62 wherein the rods are
manipulated to
actuate the wrist mechanism. For ease of manipulation, each rod 300 is joined
with a cable or
wire 302, as illustrated in Fig. 25. The wire 302 has a smaller diameter than
the rod 300 and
mates concentrically with the center 304 of the rod 300. Referring to Fig. 26,
the wire/rod
assembly 305 is then inserted through a roll pulley 310 within the tool base
62. The tool base
62 further includes rotational actuation member, such as a sector gear 312,
mounted on a
sector pivot pin 314, as shown in Fig. 27. Inserted into each sector gear 312
are two pivot
pins 320, one on each side of the gear 312. Each pivot pin 320 has a flat
surface 322 and a
crosshole 324. When inserted into a sector gear 312, the pivot pins 320 can
freely rotate to
allow maximum roll angle articulation.
[83] After the wire/rod assembly is advanced through the roll pulley 310,
the wire
302 is inserted through the crosshole 324 of a pivot pin 320 as illustrated in
Fig. 28. As
shown, crossholes 324 of each of the four pivot pins 320 are arranged between
the sector
gears 312 facing the roll pulley 310. Thus, each of the four rods 300 may be
inserted through
a separate crosshole 324. It may be appreciated that the number and
arrangement of the pivot
pins 320 is dependent on the design of the wrist mechanism. Wrist mechanisms
having
greater or fewer numbers of rods or rods in different arrangements would have
corresponding
pivot pins 320 to which the rods would be connected. Each crosshole 324 is
sized to allow
passage of the wire 302 but not the rod 300. Therefore, the rod 300 abuts the
flat surface 322
of the pivot pin 320. To maintain position of the wire/rod assembly and
abutment of the rod
300 against the flat surface 322, a crimp 330 is slid onto the wire 302, as
shown in Fig. 29,
and crimped in place.
[84] Fig. 30 is a top perspective view of the tool base 62. Rods 300 emerge
from
the roll pulley 310 and connect with the pins 320 between the sector gears 312
as described
above. Manipulation of the rods 300 actuates the wrist mechanism to position
the distal
clevis in a desired orientation. For example, the sector gears 312 can be
individually rotated
clockwise or counterclockwise by action of gears 400, as indicated by circular
arrows. Such
rotation either advances or retracts each rod 300 depending on the position of
the rods 300.
For example, by rotating the sector gear 312 clockwise, rod 300' is advanced
while rod 300"
CA 02927478 2016-04-15
18
is retracted. As described above, advancement of one rod tips the distal
clevis to face away
from the advanced rod while, in this embodiment, the rod attached to the
distal clevis in the
diametrically opposite position is simultaneously retracted. Typically, the
one rod is
advanced and the diametrically opposite rod is retracted by the same amount.
However, it
may be appreciated the advancement and retraction of these rods may vary,
usually by
attaching the rods at different locations on a particular sector gear. In any
case, advancement
and retraction of the rods provides for the pitch and yaw movements of the
distal clevis and
attached end effector. The rods 300 can also be rotated by action of gear 420
which rotates
the roll pulley 310, as indicated by a curved arrow. The roll pulley 310
rotates the shaft 54
around its central axis 51. This in turn rotates the guide tube 20 to which
the shaft 54 is
connected. Since the rods 300 pass through guide slots 30 in the guide tube 20
yet are fixed
to rotational actuation members at their backends, the guide slots 30
translate the distal ends
of the rods 300 in a circular fashion around the central axis 51 while the
backends are fixed in
place. This is possible by flexing of the rods 300. Due to the length,
thickness and flexibility
of the rods, 360 degree rotation is possible. This provides for the roll
movement of the distal
clevis and attached end effector. It may be appreciated that other back end
mechanisms may
be used to actuate and manipulate the rods 300. For instance, the rods 300 may
be
independently controlled without the use of rotational actuation members 312.
[85] Although the foregoing invention has been described in some
detail by way of
illustration and example, for purposes of clarity of understanding, it will be
obvious that
various alternatives, modifications and equivalents may be used and the above
description
should not be taken as limiting in scope of the invention which is defined by
the appended
claims.
