U.S. patent application number 10/400359 was filed with the patent office on 2004-02-05 for manipulator.
This patent application is currently assigned to MicroDexterity Systems, Inc.. Invention is credited to Stuart, J. Michael.
Application Number | 20040024385 10/400359 |
Document ID | / |
Family ID | 31190635 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040024385 |
Kind Code |
A1 |
Stuart, J. Michael |
February 5, 2004 |
Manipulator
Abstract
A manipulator for producing a remote center of revolute motion
is provided. The manipulator includes a base and a first
parallelogram linkage mechanism including a first link pivotally
mounted to the base for rotation about a first axis such that the
first link moves in a first plane. The manipulator also includes a
second parallelogram linkage mechanism including a second link
pivotally mounted to the base for rotation about a second axis such
that the second link moves in a second plane parallel to the first
plane. The first link is pivotal about a third axis perpendicular
to the first axis and the second link is pivotal about a fourth
axis perpendicular to the second axis. The first and second
parallelogram linkages are pivotally connected together by a first
connector link and a second connector link. The first and second
connector links are parallel to each other and parallel to the
first and second axes such that the first and second planes remain
parallel as the first and second links respectively rotate about
the third and fourth axes. A tool holder is pivotally connected to
the first connector link by a first pivot joint and pivotally
connected to the second connector link by a second pivot joint such
that a tool held therein is pivotable at a remote virtual pivot
point about a first remote pivot axis by pivoting the first and
second links respectively about the first and second axes and a
second remote pivot axis by pivoting the first and second links
respectively about the third and fourth axes.
Inventors: |
Stuart, J. Michael;
(Corrales, NM) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA, SUITE 4900
180 NORTH STETSON AVENUE
CHICAGO
IL
60601-6780
US
|
Assignee: |
MicroDexterity Systems,
Inc.
Memphis
TN
38119
|
Family ID: |
31190635 |
Appl. No.: |
10/400359 |
Filed: |
March 27, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10400359 |
Mar 27, 2003 |
|
|
|
09710631 |
Nov 9, 2000 |
|
|
|
60165046 |
Nov 12, 1999 |
|
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Current U.S.
Class: |
606/1 |
Current CPC
Class: |
B25J 17/0266 20130101;
A61B 2090/0814 20160201; A61B 34/70 20160201; A61B 90/11 20160201;
A61B 34/76 20160201; A61B 2090/506 20160201; A61B 2034/742
20160201; A61B 34/71 20160201; B25J 9/0072 20130101; B25J 9/1065
20130101 |
Class at
Publication: |
606/1 |
International
Class: |
A61B 017/00 |
Claims
What is claimed is:
1. A tool holding apparatus for use with a manipulator comprising:
a cartridge including a carriage for engaging a tool and a guide on
which the carriage is movably mounted for translation along a path;
and a drive unit on which the cartridge is detachably mounted and
which includes a drive mechanism drivably engageable with the
carriage to move the carriage along the path.
2. The tool holding apparatus according to claim 31 wherein the
path is a linear path.
3. The tool holding apparatus according to claim 31 wherein the
carriage is adapted for engagement with a biopsy needle.
4. The tool holding apparatus according to claim 31 wherein the
drive mechanism comprises a lead screw, a nut movable along the
lead screw and engageable with the carriage of the carriage of the
cartridge, and a motor which can rotate the lead screw to translate
the nut along the lead screw.
5. The tool holding apparatus according to claim 31 including a
support which supports the drive unit for rotation about an axis
transverse to the path of the carriage.
6. The tool holding apparatus according to claim 35 wherein the
axis is perpendicular to the path.
7. The tool holding apparatus according to claim 35 including a
drive mechanism coupled to the drive unit to rotate the drive unit
about the axis.
8. The tool holding apparatus according to claim 37 wherein the
support is adapted for engagement with a manipulator for supporting
the tool holding apparatus.
9. The tool holding apparatus according to claim 31 wherein the
carriage includes a recess for receiving an enlarged engagement
portion of a tool.
10. The tool holding apparatus according to claim 39 wherein the
recess is adapted to receive a head of a needle.
11. The tool holding apparatus according to claim 39 including a
retainer which fits over the recess to restrain the engagement
portion in the recess.
12. The tool holding apparatus according to claim 31 wherein the
cartridge includes a guide spaced from the carriage for guiding a
shank of a needle as the needle is translated by the carriage.
13. The tool holding apparatus according to claim 31 wherein the
cartridge includes a dispenser for dispensing a fluid to a patient
during the medical procedure.
14. The tool holding apparatus according to claim 43 wherein the
dispenser includes a reservoir for the fluid and a wick extending
from the reservoir for transferring fluid from the reservoir to a
patient.
15. The tool holding apparatus according to claim 43 wherein the
dispenser comprises a percutaneous injector.
16. The tool holding apparatus according to claim 31 wherein the
cartridge is adapted to release a tool after positioning.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of copending
U.S. patent application Ser. No. 09/710,631, filed Nov. 1, 1990
which claims the benefit of U.S. Provisional Application No.
60/165,046 filed Nov. 12, 1999, the disclosures of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a manipulator capable of
manipulating a tool or other object with one or more rotational
degrees of freedom in a spherical coordinate system.
BACKGROUND OF THE INVENTION
[0003] In various applications, it is desirable to be able to pivot
a tool or other object about a point in space which is remote from
equipment supporting the tool. Such a point in space is sometimes
called a virtual pivot point or a remote center of motion. An
example of a situation in which it is useful to be able to pivot a
tool about a virtual pivot point is in medical procedures. A
medical tool often needs to be pivoted about a point in, on, or in
proximity to a patient's body, but it may be undesirable to have
support structure for the tool located at the point, since the
support structure may introduce contamination into the patient's
body or interfere with the view of or access to the patient by
persons performing the medical procedures. A manipulator which can
pivot a tool about a virtual pivot point can avoid such
disadvantages of support structure.
[0004] One known type of manipulator capable of pivoting a tool in
proximity to a virtual pivot point employs a parallel linkage to
maintain the orientation of a rod-like tool remotely from the
actuation point. The parallel linkage is attached to a rotating
base assembly or has some other similar rotating structure at the
base which allows the tool to be manipulated in two degrees of
freedom (DOF) in a spherical coordinate system. An example of such
a manipulator is described in U.S. Pat. No. 5,397,323 entitled
"Remote Center-Of-Motion Robot For Surgery". This and other
conventional parallel linkage manipulators have the drawback that
the virtual pivot point must lie on a rotational axis of two of the
links of the linkage. More specifically, the virtual pivot point
must lie in the same plane as the rotational axis of the base and
must be inline with the distal pivots of the manipulator. The
manipulator disclosed in U.S. Pat. No. 5,397,323 only produces an
approximate remote center of motion if the tool is mounted in from
the distal pivots, since the tool actually sweeps an arc in one
plane rather than pivoting around a point.
[0005] One disadvantage of these constraints on the location of the
virtual pivot point is that it can be difficult to position the
manipulator with respect to a patient's body and other equipment.
In particular, the requirement that the virtual pivot lie in the
same plane as the rotating structure at the base can cause
clearance problems with a patient or with other equipment being
used in the medical procedure such as imaging equipment. The
clearance problems can require the patient or a person performing a
medical procedure to assume an uncomfortable position.
[0006] In addition, the requirement that the virtual pivot point be
inline with the distal pivots of the manipulator can make
conventional parallel linkage manipulators difficult to use in
biopsies and other medical procedures performed in conjunction with
imaging systems such as computer tomography (CT) equipment, x-ray
equipment or magnetic resonance imaging equipment. In a biopsy
performed using imaging equipment, a biopsy needle is inserted into
a patient's body while the patient is outside the imaging
equipment. The patient is then placed inside the imaging equipment
and an image is taken to determine the location of the biopsy
needle with respect to the region of the body where the biopsy is
to be performed. It is frequently difficult or unsafe for a human
operator to adjust the position of the biopsy needle while an image
is being taken. For example, there often is a very limited amount
of space between the interior of the imaging equipment and the
patient's body. Additionally, the operator could be exposed to
harmful radiation from the imaging equipment or the operator could
interfere with the imaging process. Thus, each time the position of
the biopsy needle has to adjusted, the patient is withdrawn from
the imaging equipment and then reintroduced into the imaging
equipment after the position of the biopsy needle has been
adjusted. Obviously, such a procedure is very time consuming and
imprecise.
[0007] Recent advances in CT technology have decreased the time to
generate an image to the point that near real time video images can
be produced. With this technology, a doctor can place a medical
tool with high precision, but he must be very close to the
radiation source and receives a higher dose of harmful
radiation.
[0008] One way in which these problems can be addressed is by using
a manipulator that is capable of adjusting the position of a needle
or object with respect to a patient's body while imaging is being
carried out. However, with conventional parallel linkage
manipulators that can produce a remote center of motion, the distal
pivots are in the same plane as the image of interest and tend to
distort that image. If the tool is offset from the distal pivots of
the manipulator, as is the case with the manipulator described in
U.S. Pat. No. 5,397,323, the tool will no longer rotate about a
true virtual pivot point. Instead, the tool will move in a small
arc as the manipulator is swung about.
SUMMARY OF THE INVENTION
[0009] Accordingly, in view of the foregoing, a general object of
the present invention is to provide a manipulator capable of
manipulating a tool or other object with two rotational degrees of
freedom about a virtual pivot point with fewer constraints on the
position of the manipulator relative to the virtual pivot point
than with conventional manipulators.
[0010] Definition Of Terms
[0011] The term link will be used herein to refer to a member which
functions as the equivalent of a rigid body when moving parallel to
a specific plane. Thus, a link may be a rigid body, or it may
comprise a plurality of components which can move together as a
single body parallel to the specific plane but which are movable
with respect to each other in a plane transverse to the specific
plane. For example, in some embodiments, a group of components
which function as a parallel linkage for movement parallel to a
first plane may function as a single link for movement parallel to
a second plane transverse to the first plane.
[0012] Two links are considered parallel to each other when a line
connecting two rotational axes of one link is parallel to a line
connecting two rotational axes of the other link.
[0013] The term pivot point will be used to refer to a point at
which a link is physically connected to another member for pivoting
with respect to the other member about an axis, while the term
virtual pivot point will refer to a point in space at which a link
can pivot about an axis passing through the virtual pivot point
without the link having to be physically supported at the virtual
pivot point. Pivot can provide one, two or three degrees of
rotational freedom.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic side elevation of a kinematic model of
an example of a conventional parallel linkage manipulator.
[0015] FIG. 2 is a schematic side elevation of a kinematic model of
one aspect of a manipulator according to the present invention.
[0016] FIGS. 3 and 4 are schematic side views of two examples of
links which can be employed in the present invention.
[0017] FIG. 5 is a schematic side elevation of a kinematic model of
a variation of the example of FIG. 2.
[0018] FIG. 6 is a schematic side elevation of a kinematic model of
another variation of the example of FIG. 2.
[0019] FIG. 7 is an isometric view of another embodiment of a
manipulator constructed in accordance with the present
invention.
[0020] FIG. 8a is an isometric view and FIG. 8b is a front
elevation of a kinematic model of another aspect of a manipulator
according to the present invention.
[0021] FIG. 9 is an isometric view of an embodiment of a
manipulator according to the present invention.
[0022] FIG. 10 is a side elevation of the embodiment of FIG. 9.
[0023] FIGS. 11 and 12 are respectively a side elevation and an
isometric view of the embodiment of FIG. 9 rotated backwards from
the position shown in FIG. 9.
[0024] FIGS. 13, 14, and 15 are respectively a side elevation, an
isometric view, and a front elevation of the embodiment of FIG. 9
rotated sideways from the position shown in FIG. 9.
[0025] FIG. 16 illustrates an example of the use of motors to drive
the embodiment of FIG. 9.
[0026] FIG. 17 is an isometric view of another embodiment of a
manipulator according to the present invention.
[0027] FIG. 18 is a side elevation of the embodiment of FIG.
15.
[0028] FIGS. 19 and 20 are respectively a side elevation and an
isometric view of the embodiment of FIG. 18 rotated backwards from
the position shown in FIG. 18.
[0029] FIGS. 21, 22, and 23 are respectively a side elevation, an
isometric view, and a front elevation of the embodiment of FIG. 18
rotated sideways from the position shown in FIG. 18.
[0030] FIGS. 24 and 25 are schematic side elevations of links
equipped with different means for maintaining the attitude of links
from that shown in FIG. 18.
[0031] FIG. 26 is an isometric view of another embodiment of a
manipulator according to the present invention.
[0032] FIG. 27 is a side elevation of the embodiment of FIG.
26.
[0033] FIG. 28 is a side elevation of a portion of the embodiment
of FIG. 26 supporting a tool holder.
[0034] FIG. 29 is a side elevation view of an embodiment of the
tool holder of FIG. 28.
[0035] FIG. 30 is a top view of the tool holder of FIG. 29 with the
cartridge removed.
[0036] FIG. 31 is a isometric view of the cartridge of FIG. 29 with
a needle removed.
[0037] FIG. 32 is a side elevation of the cartridge of FIG. 29 in a
partially disassembled state.
[0038] FIG. 33 is an enlarged transverse cross-sectional view of
the carriage guide of the cartridge of FIG. 31.
[0039] FIG. 34 is a plan view of the carriage drive unit of the
tool holder of FIG. 29 with the cover of the drive unit shown in
phantom.
[0040] FIG. 35 is a side elevation of the carriage drive unit of
FIG. 34.
[0041] FIGS. 36 and 37 are longitudinal cross-sectional views of
the dispensing units of the cartridge of FIG. 31.
[0042] While the invention will be described and disclosed in
connection with certain preferred embodiments and procedures, it is
not intended to limit the invention to those specific embodiments.
Rather it is intended to cover all such alternative embodiments and
modifications as fall within the spirit and scope of the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0043] Referring now more particularly to FIG. 1 of the drawings
there is schematically shown a kinematic model of a conventional
parallel linkage manipulator in which the virtual pivot point or
remote center of motion produced by the manipulator is constrained
to lie in the same plane as the roll axis of the main mechanism and
to be inline with the distal pivots. The illustrated conventional
manipulator includes two parallel linkages 10 and 20, each linkage
having a plurality of links movable parallel to the plane of the
drawing. For ease of viewing, the rotational axes of the links are
shown extending diagonally, but they actually extend perpendicular
to the plane of the drawing.
[0044] A first parallel linkage 10 includes three links 11, 12, and
13. Links 11 and 12 are pivotable about parallel axes 14 and 15 at
their lower ends, which may be supported by a base 18 or other
support structure such that axes 14 and 15 remain stationary with
respect to each other. Links 11 and 12 are also pivotably connected
to link 13 at their upper ends for pivoting about axes 16 and 17,
which are both parallel to axis 14. A plane containing axes 16 and
17 is parallel to a plane containing axes 14 and 15, and a plane
containing axes 14 and 16 is parallel to a plane containing axes 15
and 17.
[0045] The second parallel linkage 20 includes four links, i.e.,
link 12, link 21, link 22, and link 23 which supports a tool 24.
Link 21, which is rigidly connected to link 13, is pivotably
connected at its opposite ends to links 12 and 23 for pivoting
about axis 17 and axis 26, which are parallel to axis 14. Link 22,
in turn, is pivotably connected at its opposite ends to links 12
and 23 for pivoting about axis 25 and axis 27, both of which are
parallel to axis 14. Axis 26 is coplanar with axes 16 and 17. A
plane containing axes 25 and 27 is parallel to a plane containing
axes 17 and 26. Axis 25 is coplanar with axes 15 and 17 and lies in
a plane parallel to a plane containing axes 26 and 27.
[0046] When links 11 and 12 are simultaneously pivoted about axes
14 and 15, link 23 and the tool 24 pivot about axis 28 at a virtual
pivot point 29. Because axis 26 is coplanar with axes 16 and 17,
the virtual pivot point 29 is constrained to lie in a plane
containing axes 14 and 15. Moreover, the virtual pivot point 29 is
also constrained to be inline with the pivots connecting link 23 to
links 21 and 22. As described above, depending on the situation and
application, these constraints can create problems. In particular,
in medical applications, the fact that the virtual pivot point 29
is constrained to lie in a plane containing axes 14 and 15 can make
it difficult to provide adequate clearance between the manipulator
and portions of the patient's body not involved in the procedure
and between the manipulator and any other equipment involved in the
procedure such as imaging equipment. The constraint that the
virtual pivot point 29 be inline with the pivotal attachments of
link 23 raises difficulties when the manipulator is used in
conjunction with imaging equipment. In particular, link 23, which
supports the tool, is typically in the same plane as the image of
interest and tends to distort that image.
[0047] In accordance with one aspect of the present invention, a
manipulator can be provided which does not have the virtual pivot
point constraints that are associated with the conventional
arrangement of FIG. 1. For example, FIG. 2 schematically
illustrates a kinematic model of a manipulator according to the
present invention in which the virtual pivot point is not
constrained to be in the same plane as the base pivot axes 14 and
15. This manipulator is similar to that of FIG. 1 in that it
includes two parallel linkages 10 and 20A, but link 21 of linkage
20A has been rotated with respect to link 13 relative to its
orientation in FIG. 1 so that the two links 13 and 21 are no longer
aligned, i.e., so that axis 26 is not coplanar with axes 16 and 17.
Link 22 remains parallel to link 21.
[0048] As in FIG. 1, when links 11 and 12 are pivoted about axes 14
and 15, link 23 and the tool 24 which it supports pivot about axis
28 at virtual pivot point 29. However, since axis 26 is not
coplanar with axes 16 and 17, axis 28 and thus the virtual pivot
point 29 are spaced from the plane containing axes 14 and 15. This
can make the manipulator of FIG. 2 more convenient to use than the
manipulator of FIG. 1 and more comfortable for both an operator of
the manipulator and a patient undergoing treatment. Depending upon
whether link 21 is bent upward or downward with respect to link 13,
the virtual pivot point 29 may be above or below the plane
containing axes 14 and 15. The distance of the virtual pivot point
29 above or below the plane can be varied by varying the angle
between links 13 and 21 or the lengths of the various links.
[0049] In FIG. 2, links 13 and 21 are both straight members at an
obtuse angle to each other, but they may have any shapes such that
axis 26 is spaced from the plane containing axes 16 and 17. For
example, link 21 can be curved or crank shaped, as schematically
shown in FIGS. 3 and 4, respectively. Moreover, link 13 is shown
rigidly connected to link 21 in FIG. 2, but, alternatively, it may
be rigidly connected to link 22, as schematically shown in FIG. 5.
Alternatively, link 13 may remain rigidly connected to link 21, and
an additional link rigidly connected to link 22 may be pivotably
connected between link 11 and link 12 parallel to link 13.
Likewise, link 21 is illustrated as being integrally formed with
link 13, but the two links may be separately formed and rigidly
connected to each other in any suitable manner.
[0050] In FIG. 2, link 23 has a length such that the tip of the
tool 24 coincides with the virtual pivot point 29, but the virtual
pivot point 29 may be at any desired location with respect to link
23 and the tool 24. If the virtual pivot point 29 represents a
point on the skin of a patient which is to be contacted by the tool
24, the lower end of the tool 24 may coincide with the virtual
pivot point 29. If the tool 24 is to be inserted through an
incision or other opening in the body of a patient to access a
location within the patient's body, the virtual pivot point 29 may
be a point within the body wall of the patient about which link 23
is to be pivoted, in which case the virtual pivot point 29 may
coincide with a location on link 23 located above the tool 24. If
the tool 24 is a laser or other device which is being used to treat
a location on the patient's skin without contacting the location,
the virtual pivot point 29 may coincide with the location on the
skin and be spaced from both link 23 and the tool 24. Thus, the
location of the virtual pivot point 29 with respect to link 23 and
the tool 24 may vary depending upon the nature of the tool 24 and
the type of procedure which is to be performed with the tool
24.
[0051] As will be appreciated, a manipulator according to the
present invention can be used to manipulate a wide variety of
objects, but it is particularly suitable for use in manipulating
medical tools. A few examples of tools which can be used with a
manipulator according to the present invention are cutting devices,
needle holders, staples, forceps, clamps, probes, imaging devices,
lasers, needles or other biopsy devices, devices for administering
medication or other substances, or other devices for surgical,
therapeutic, or diagnostic purposes. Moreover, while the present
invention is described herein in connection with performing medical
procedures, it will be readily appreciated that it is equally
applicable to other types of applications involving
manipulators.
[0052] In the embodiment shown in FIG. 2, the virtual pivot point
29 is still inline with the pivotal connections of the link 23 to
links 21 and 22. Therefore, in order for the tool 24 to contact the
virtual pivot point 29, the tool 24 must be mounted on link 23
inline with those pivotal connections. As noted above, this
constraint can pose problems when the manipulator is used in
conjunction with an imaging device in that link 23 obscures the
image of the relevant area. Thus, according to another aspect of
the present invention a manipulator can be provided in which the
virtual pivot point is offset from the line defined by the pivots
of link 23. As schematically shown in FIG. 6, by appropriately
shaping the links of a manipulator, the virtual pivot point 29 can
be spaced from the line defined by the pivots of link 23 supporting
the tool 24. The manipulator of FIG. 6 is generally similar to the
manipulator of FIG. 2, but link 12 of FIG. 2, for which axes 25,
17, and 15 are coplanar, has been replaced by a link 12A having a
shape such that axis 25 is spaced from a plane connecting axes 15
and 17. Link 11A, which is parallel to link 12A, is shown having a
non-linear shape similar to that of link 12A, but it may have any
shape such that a plane containing axes 14 and 16 is parallel to a
plane containing axes 15 and 17. Except for links 11A and 12A, the
arrangement of the links is the same as in FIG. 2. The manipulator
illustrated in FIG. 6 would function identically if it is arranged
similar to the link arrangement in FIG. 5 with only links 11A and
12A being substituted for links 11 and 12.
[0053] As in the previous examples, when links 11A and 12A are
pivoted about axes 14 and 15, link 23 and the tool 24 which it
supports pivot about an axis 28, which is parallel to axis 14, at a
virtual pivot point 29. However, due to the shape of link 12A, the
virtual pivot point 29 is spaced from a line defined by the pivots
of link 23. Therefore, in this case, the tool 24 can be supported
by a tool holder 30 which is spaced forward (with reference to FIG.
6) of link 23 and still contact the virtual pivot point 29. As will
be appreciated, the virtual pivot point could be spaced rearward of
link 23 by configuring link 12A such that axis 25 is spaced forward
of the plane connecting axes 15 and 17 and configuring link 11A
with a complementary shape. Moreover, varying the shape of links
11A and 12A can vary the distance that the virtual pivot point is
offset from the pivots of link 23. The spatial relationship between
axes 17, 25 and 15 is maintained in the spatial relationship
between axes 26 and 27 and the axis 28 at the virtual pivot point.
While the embodiment of the invention shown in FIG. 6 is also
configured such that the links 13 and 21 are not in alignment so as
to also offset the virtual pivot point 29 from the plane of pivots
14 and 15, the embodiment of the invention shown in FIG. 6 could
also be configured such that links 13 and 21 are in alignment and
the virtual pivot is in the plane of pivots 14 and 15.
[0054] In accordance with another aspect of the present invention,
a manipulator can be provided which is capable of moving a tool
about a virtual pivot point with two degrees of freedom.
Specifically, in some instances, it may be sufficient to rotate a
tool with a single degree of freedom about a single axis passing
through a virtual pivot point. In other situations, it may be
desirable to also rotate a tool with another degree of freedom
about a second axis passing through the virtual pivot point, such
as an axis perpendicular to the first axis. An illustrative
embodiment of a manipulator 302 capable of producing movement of a
tool 304 about a virtual pivot point 305 with two degrees of
freedom is shown in FIG. 7. The manipulator 302 generally comprises
two parallelogram linkage mechanisms 306, 308 that move in parallel
planes and are linked together.
[0055] In the embodiment of the invention illustrated in FIG. 7,
each of the two parallelogram linkage mechanisms 306, 308 comprises
a 4-bar linkage. Each includes parallel front and rear vertical
links 310, 312, 314, 316 that at one end are pivotally connected to
a base 320 and a third horizontal link 322, 324 that pivotally
connects the opposite ends of the front and rear vertical links. In
each mechanism, the horizontal link 322, 324 is parallel to a line
defined by the base pivots of the respective pair of vertical links
310, 312 and 314, 316. Each of the vertical links 310, 312, 314,
316 is mounted to the base 320 and to its respective horizontal
link 322, 324 for pivotal movement about two perpendicular axes. In
the illustrated embodiment this is accomplished by at the base
pivots by pivotally connecting each vertical link to a
corresponding roller 326, 328. For example, vertical link 310 is
pivotally connected to a roller 326 which is rotatably supported by
base 320. The pivotal connection to the roller 326 allows vertical
link 310 to rotate about axis 332 while the roller allows vertical
link 310 to rotate about axis 330. At the opposing end, vertical
link 310 is pivotally connected to horizontal link 322 for rotation
about axis 334. Horizontal link 322 is, in turn, rotatably
supported such that vertical link 310 can rotate about axis 336
which is perpendicular to axis 334. The other vertical links 312,
314, 316 have similar pivotal connections to the base 320 and their
respective horizontal link 322, 324 such that each is rotatable
with two degrees of freedom with respect to the base and the
corresponding horizontal link about two perpendicular axes. For
ease of reference, besides the rotational axes for vertical link
310, only the rotational axes 337 and 338 for the connection of
vertical link 314 to the base and the rotational axes 342 and 344
for the connection of vertical link 314 to horizontal link 324 are
shown in FIG. 7.
[0056] As vertical links 310 and 314 are rotated respectively about
axes 332 and 337 through operation of their respective
parallelogram linkages, the vertical links 310 and 314 move in
parallel planes. To ensure that these planes are constrained to
move in parallel relation as the vertical links 310 and 314 rotate
respectively about axis 330 and 338, the two parallelogram linkages
306, 308 are connected together at their forward ends by upper and
lower connector links 346 and 348. The upper and lower connector
links 346, 348 extend parallel to each other and interconnect, in
this case, vertical link 310 of the first parallelogram linkage 306
and vertical link 314 of the second parallelogram linkage 308. In
particular, the upper connector link 346 is pivotally connected
adjacent one end to horizontal link 322 (and thereby vertical link
310) for rotation relative to vertical link 310 about axis 336 and
adjacent the opposing end to horizontal link 324 (and thereby
vertical link 314) for rotation relative to vertical link 314 about
axis 342. Similarly, the lower connector link 348 is pivotally
connected adjacent one end to vertical link 310 through an
intermediate horizontal link 354 for rotation about axis 350 and
adjacent the opposing end to vertical link 314 through an
intermediate horizontal link 356 for rotation about axis 352.
[0057] To impart some stress into the manipulator 302 and thereby
reduce the free play, the manipulator illustrated in FIG. 7
includes additional links and connections. In particular, each of
the parallelogram linkage mechanisms 306, 308 includes an
intermediate horizontal link 354, 356 which interconnects the two
vertical links. Using the interconnection between vertical link 310
and intermediate horizontal link 354 as an example, vertical link
310 is pivotal about axes 350 and 358 relative to the intermediate
horizontal link. In this instance, the pivotal movement about axis
350 is achieved via rotatably supporting the intermediate
horizontal link 354 at either end in a similar manner to the
horizontal links 322 and 324. As shown in FIG. 7, axis 350 is
parallel to axis 336 and axis 358 is parallel to axis 334. The
other vertical links have similar pivotal connections with the
respective intermediate horizontal links. The illustrated
manipulator further includes an upper support bar 360 extending
parallel to the horizontal links 322, 324 of the two parallelogram
linkages 306, 308 and an intermediate support bar 362 that extends
parallel to the intermediate horizontal links 354, 356.
Additionally, the manipulator includes rear connector links 364,
366 which interconnect vertical links 312 and 316 and horizontal
links 322, 324 at the rear ends of the parallelogram linkages. The
rear connector links 364, 366 and the upper and lower connector
links 346, 348 at the forward end of the parallelogram linkages
further serve the function of rotatably supporting the horizontal
links 322, 324 and the intermediate horizontal links 354, 356.
[0058] Like the intermediate horizontal links 354, 356, the support
bars 360, 362 and rear connector links 364, 366 are redundant and
help introduce more rigidity into the manipulator 302 thereby
reducing free play. This reduction in free play is useful in
surgical applications, however, it will be appreciated that the
intermediate horizontal links and support bars are not necessary
parts of the present invention. Furthermore, while the illustrated
embodiment produces certain pivotal movements by rotatably
supporting either end of the horizontal links and the intermediate
horizontal links, other types of pivotal connections between the
various links could be used. Similarly, the upper and lower
connector links could be connected directly to vertical links 310
and 314 rather than through the horizontal links 322, 324 and
intermediate horizontal links 354, 356 as in the illustrated
embodiment.
[0059] For supporting the tool 304 for rotary movement at the
remote virtual pivot point 305 with two degrees of freedom, the
manipulator 302 includes a tool holder link 368 that is pivotally
connected to the upper connector link 346 and pivotally connected
to the lower connector link 348. In the illustrated embodiment, the
pivots for the tool holder link 368 are at the free end of extended
portions of the connector links 370, 372 which extend parallel to
each other and outwardly away from the forward end of the two
parallelogram linkages. The pivotal connection of the tool holder
link 368 with the upper connector link 346 permits pivotal movement
about axis 374 (via yoke 376) and axis 378 (via pivot joint 380)
which intersects and is perpendicular to axis 374. Similarly, the
pivotal connection of the tool holder link 368 with the lower
connector link 348 permits pivotal movement about axis 382 (via
yoke 384) and axis 386 (via pivot joint 388) which intersects and
is perpendicular to axis 382. With this arrangement, a tool held by
the tool holder link 368 will rotate about axis 390 at the virtual
pivot point 305 when the vertical links 310, 312 are pivoted
side-to-side about axes 330 and 338 and the tool rotate about axis
392 at the virtual pivot point when the vertical links are pivoted
front-to-back about axes 332 and 333. During this pivotal movement,
the upper and lower connector links 346, 348 are constrained to
move in parallel relation to each other by the two parallelogram
linkage mechanisms 306, 308.
[0060] In the embodiment illustrated in FIG. 7, the vertical links
310, 312, 314, 316 are offset rearward such that the pivotal
connection with the intermediate horizontal links 354, 356 (and in
turn the lower connector link 348) is not co-linear with a line
defined by the connections of the vertical links with the
horizontal links 322, 324 and the base 320. This arrangement is
similar to the one degree of freedom manipulator illustrated in
FIG. 6 and results in a shift of the virtual pivot point forward
from a line intersecting the pivotal connections of the tool
support link.
[0061] A further embodiment of a manipulator constructed in
accordance with the present invention is illustrated in FIG. 9. The
embodiment of FIG. 7 is over constrained and includes redundant
links. In the embodiment of FIG. 9, these redundant links have been
removed. The embodiment of FIG. 9 functions in the same manner as
the FIG. 7 embodiment and can still be understood as being based on
two parallelogram linkage mechanisms operating in parallel that are
connected together. However, in the case of the embodiment of FIG.
9, the two parallelogram linkages share a common rear vertical link
50 and a common horizontal link 70. The intermediate horizontal
links and the rear connector links of the FIG. 7 embodiment have
been eliminated and there are no additional support bars in the
manipulator.
[0062] Another way in which the FIG. 9 embodiment can be understood
is by taking a parallelogram linkage like that shown in FIG. 2 and
replacing one of the parallel vertical links with a second
parallelogram linkage which moves in a plane perpendicular to the
first parallelogram linkage. To this end, FIG. 8a is a schematic
isometric view of a manipulator, and FIG. 8b is a schematic front
elevation of the manipulator pivoted sideways with respect to the
vertical. The manipulator includes a parallel linkage 40 including
links 41-44. Links 41 and 42, which are parallel to each other, are
pivotable at their lower ends about parallel axes 45 and 46,
respectively, with the lower ends of the links being supported by a
base or other suitable structure such that axes 45 and 46 remain
stationary with respect to each other. Links 43 and 44, which are
parallel to each other, are each pivotably connected to links 41
and 42. Link 43 is pivotably connected to link 41 for pivoting
about axis 47, and it is pivotably connected to link 42 for
pivoting about axis 48. Link 44 is pivotably connected to link 41
for pivoting about axis 49 between axes 45 and 47, and it is
pivotably connected to link 42 for pivoting about axis 50 between
axes 46 and 48. All of axes 45-50 are parallel to each other.
[0063] Link 51 and link 52, which is parallel to link 51, extend
transversely from link 43 and link 44, respectively. Links 51 and
52 remain in parallel relation as parallel linkage 40 moves from
side to side in a plane and are illustrated as being rigidly
connected to links 43 and 44, but they may be pivotably connected
to links 43 and 44 if some means is provided for constraining links
51 and 52 such that they move in parallel relation to each other.
Links 51 and 52 are pivotably connected to link 53, which supports
a tool 54 at its lower end, for pivoting about axes 55 and 56,
respectively, which are parallel to axis 45. Axis 55 is spaced from
a plane containing axes 47 and 48, and axis 56 is spaced from a
plane containing axes 49 and 50, while a plane containing axes 55
and 56 is parallel to a plane containing axes 45, 47, and 49.
[0064] With this arrangement, when links 41 and 42 are
simultaneously pivoted about axes 45 and 46, as shown in FIG. 8b,
link 53 and the tool 54 pivot at a virtual pivot point 58 about an
axis 57 which is parallel to axis 45 but is spaced from a plane
containing axes 45 and 46. Thus, by combining the aspect of the
invention illustrated in FIGS. 7 and 8 with the aspect of the
invention illustrated in FIG. 2, a manipulator according to the
present invention can pivot a tool about a virtual pivot point with
two degrees of freedom. For example, if link 12 of FIG. 2 is made a
parallel linkage similar to linkage 40 of FIG. 8a, and if links 21
and 22 of FIG. 2 can pivot with respect to link 23 with two degrees
of freedom, then a tool can be made to pivot with two degrees of
freedom at a virtual pivot point about two orthogonal axes, such as
axis 28 of FIG. 2 and axis 57 of FIG. 8a.
[0065] Referring again to the manipulator shown in FIGS. 9-15, the
vertical link 50 is pivotably supported at its lower end by a base
55 for pivoting about axis 80 and axis 81 perpendicular to and
intersecting axis 81. Two vertical links 61 and 62 extend parallel
to each other and to vertical link 50. Vertical links 61 and 62 are
supported by the base 55 for movement parallel to link 50. Like the
FIG. 7 embodiment, vertical links 61 and 62 are interconnected by
parallel upper and lower connector links 64 and 65. Horizontal link
70 is pivotably connected at one end to link 50 for pivoting about
axis 82 parallel to axis 80 and about axis 83 perpendicular to and
intersecting axis 83 and parallel to axis 81. At its other end,
link 70 is pivotably connected to the upper connector link 64 for
pivoting with respect to the upper connector link about axis 89
parallel to axis 82. The upper connector link is pivotally
connected to vertical link 62 for pivotal movement about axes 88
and 89 and to vertical link 61 for pivotal movement about axes 87
and 89. The lower connector link 65 is pivotally connected to
vertical link 62 for pivotal movement about axes 93 and 94 and to
vertical link 61 for pivotal movement about axes 92 and 94.
[0066] As with the FIG. 7 embodiment, the upper and lower connector
links 64 and 65 include respective extended portions 71 and 75
which extend parallel to each other for supporting a tool holder
link 78. The tool holder link 78 is adapted to support a tool and
is connected to the upper connector link extended portion 71 for
pivotal movement about axis 90 parallel to axis 81 and about axis
91 (via yoke 73) perpendicular to and intersecting axis 90. The
tool holder link 78 is connected to the lower connector link
extended portion 75 for pivotal movement about axis 95 and about
axis 96 (via yoke 76) perpendicular to and intersecting axis 95.
The yokes 73 and 76 are pivotally connected to the ends of the
extended portions of the upper and lower connector links 71 and 75
so as to produce the pivotal movement about axes 90 and 95.
[0067] The various links can be configured in a wide variety of
ways and result in kinematically equivalent arrangements, all of
which are included in the scope of the present invention. Thus, the
structure shown in FIG. 9 is but one example of a manipulator
according to the present invention. In the illustrated embodiment,
vertical link 50 includes lower and upper yokes 51, 52 secured to
opposite ends of the link. The lower yoke 51 is connected to a yoke
56 mounted on the base 55 by a spider 56a to define a universal
joint pivotable about axes 80 and 81. The upper yoke 52 is
connected to a yoke 70a on the end of link 70 by a spider 70b to
define another universal joint pivotable about axes 82 and 83.
[0068] Vertical links 61 and 62 are similar in structure to link
50, each including a yoke at either end. The lower yoke of vertical
link 61 is pivotably connected to a first end of a lower pivotal
support 63 for pivoting about axis 85, and the upper yoke is
pivotably connected to one end of the upper connector link 64 for
pivoting about axis 87 which is parallel to axis 85. The lower yoke
of link 62 is pivotably connected to the second end of the lower
pivotal support 63 for pivoting about axis 86, which is parallel to
axis 85, and the upper yoke of link 62 is pivotably connected to
the second end of the upper connector link 64 for pivoting about
axis 88, which is parallel to axis 85. The lower pivotal support 63
is pivotably supported by a yoke 57 mounted on the base 55 for
pivoting about axis 84, which is parallel to axis 89. The lower
connector link 65 includes two yokes 65a. One of the yokes 65a is
pivotably connected to vertical link 61 and the other yoke 65a is
pivotably connected to vertical link 62.
[0069] When vertical link 50 is pivoted about axis 80 and the
vertical links 61 and 62 is pivoted about axis 84, as shown, for
example, by FIG. 11, the manipulator behaves like the kinematic
model of FIG. 2, with the interconnected vertical links 61 and 62
functioning as a single rigid link corresponding to link 12 of FIG.
2. As a result, the tool holder link 78 and the tool 79 pivot at a
virtual pivot point 99 about axis 97, which is parallel to axis 84.
When vertical link 50 is pivoted about axis 81 and vertical links
61 and 62 are pivoted about axes 85 and 86, respectively, as shown,
for example, by FIGS. 14 and 15, the manipulator behaves like the
kinematic model of FIGS. 8a and 8b, and link 78 and the tool 79
pivot at the virtual pivot point 99 about axis 98, which is
parallel to axis 81 and perpendicular to axis 97 and intersects
axis 97 at the virtual pivot point 99. The upper connector link
extended portion 71, which corresponds to link 21 of FIG. 2, is not
aligned with the horizontal link 70, so the virtual pivot point 99
is spaced from a plane containing axes 85 and 86.
[0070] The tool 79 may remain stationary with respect to the tool
holder link 78, or the tool holder link 78 may include structure
which enables the tool 79 to be manipulated with respect to the
tool holder link 78 with one or more degrees of freedom. For
example, the tool holder link 78 may be capable of translating the
tool 79 in its axial direction, of rotating the tool 79 about its
longitudinal axis, and of pitching and/or yawing the tool 79 with
respect to the tool holder link 78.
[0071] Vertical links 50, 61, and 62 are shown pivotably supported
by a common base 55, but they may be mounted on separate members.
The base 55 is shown sitting on a crank-shaped support 58 having a
support pin 59, the upper end of which represents the location of
the virtual pivot point 99. However, the pin 59 performs no
function in the operation of the manipulator and is present merely
to make the location of the virtual pivot point 99 easier to
identify in this figure. In actual use, the manipulator can be
mounted on any convenient support member, which may be stationary
or movable. For example, the manipulator may be mounted on a wall,
a ceiling, a support stand, a movable gantry, an operating table,
an imaging device or other medical device with which the
manipulator is to be used, or the distal end of another
manipulator.
[0072] In FIG. 9, the vertical links 61 and 62 are located between
vertical link 50 and the tool holder link 78. Alternatively, the
positions of vertical link 50 and the vertical links 61 and 62 can
be interchanged, with vertical link 50 located between vertical
links 61 and 62 and tool holder link 78.
[0073] The links of a manipulator according to the present
invention can be of fixed length, or they can be of adjustable
length to enable the location of the virtual pivot point to be
adjusted without having to move the entire manipulator. An
adjustable link can have a variety of structures. For example, it
can be a member with telescoping or otherwise overlapping portions
and which can be lengthened or shortened either by hand or by an
actuator, such as a motor or a cylinder, connected between the
different telescoping portions of the link.
[0074] Additionally, the extended portions 71, 75 of the upper and
lower connector links are shown centered between the pivots of the
vertical links 61 and 62. However, this is not necessary. The
extended portions 71, 75 only need to be connected to the upper and
lower connector links 64, 65 in a plane parallel to a plane
containing link vertical link 50. By combining this possible linear
translation of the attachment points of the extended portions 71,
75 with telescoping extended portions and angular variations
between the extended portion 71 of the upper connector link and the
horizontal link 70, three dimensional translational motion can be
defined to allow the translation of the virtual pivot pivot 99 to
any point within the reach of the mechanism.
[0075] The manipulator of FIG. 9 can be operated by exerting a
force on one or more of the vertical links 50, 61, and 62 to cause
the link to pivot about its lower end. The manipulator can be
operated manually or by actuators employing electrical, pneumatic,
or hydraulic power, for example. When the manipulator is operated
manually, one of the links, such as vertical link 50, can be
directly grasped by the hand of a user, or a lever, a wheel, a
crank, or other manually operable member can be mechanically
coupled to one or more of the links to pivot the link with one or
more degrees of freedom. Additionally, the manipulator configured
such that it can be locked in position either by the actuators or
by brakes or another type of mechanical lock.
[0076] Actuators for driving the manipulator can be connected to
the manipulator at a variety of locations to exert a torque on a
link about one or more of the rotational axes. For example, as
shown in FIG. 16, motors 110 and 111, which may include a reduction
gear, can be mounted on each yoke 51, 56 of the universal joint at
the lower end of vertical link 50. In this example, each motor 110,
111 has an output shaft coaxially secured to one leg of the spider
56a of the universal joint and a housing, with respect to which the
output shaft can rotate, secured to the yoke so that when the motor
is operated, the spider 56a and the yoke 51 or 56 are made to
undergo relative rotation about the axis of the output shaft. When
motor 110 is operated, vertical link 50 pivots about axis 80, and
when motor 111 is operated, vertical link 50 pivots about axis 81.
Alternatively, motors can be mounted on the lower yoke of one or
both of vertical links 61 and 62 to pivot these links about axes 85
and 86, and a motor can be connected to lower pivotal support rod
63 to rotate the parallel linkage 60 about axis 84.
[0077] The motors may be controlled in response to signals from a
suitable input device. In particular, the manipulator of the
present invention can be used as a slave robot in a master-slave
robotic system. In such a system, a surgeon/operator provides
position input signals to the "slave" manipulator via a master or
haptic interface which operates through a controller or control
console. Specifically, through the use of an input device on the
haptic interface such as a joystick, foot pedal or the like, the
surgeon indicates the desired movement of the tool held by the
manipulator. The haptic interface relays these signals to the
controller which, in turn, applies various desired predetermined
adjustments to the signals prior to relaying them to the slave
manipulator. Any haptic interface can be used to control the
manipulator via the controller. Other input devices such as a
keyboard, a tape memory or other storage device, a mouse, a
digitizer, a computer glove, or a voice operated controller could
also be used.
[0078] Based on the signals provided by the controller, the
manipulator executes the desired movement or operation of the tool.
Thus, any desired dexterity enhancement can be achieved by setting
up the controller to perform the appropriate adjustments to the
signals sent from the haptic interface. For example, this can be
accomplished by providing the controller with software which
performs a desired dexterity enhancement algorithm. Software
dexterity enhancement algorithms can include position scaling,
force scaling, tremor filtering and gravity compensation. These and
other examples of possible algorithms are well known in the field
of robotics and described in detail in published literature.
[0079] The various actuators and/or the tool holder link can also
be equipped with sensors for sensing the forces or torques applied
thereon so as to enable a determination of the forces and torques
applied to the tool. This information can again be used in a
feedback control loop to the controller, for example to allow force
feedback to the input device of the haptic interface. Of course,
any known method for measuring forces and/or torques can be used,
including, for example, foil type or semiconductor strain gauges or
load cells. The forces also could be displayed on a display device
for an operator of the manipulator. Additional details regarding
input devices, controllers and actuators suitable for manipulators
to be used in medical imaging environments is disclosed in commonly
assigned U.S. application Ser. No. 09/442,966 entitled "Medical
Manipulator For Use With An Imaging Device" which is hereby
incorporated by reference.
[0080] In the manipulator embodiments shown in FIGS. 2-16,
parallelogram mechanisms comprising four bar linkages are employed
to constrain certain links to move in parallel relation as the
manipulator swings back and forth to move a tool in space. However,
as will be appreciated by those skilled in the art, parallelogram
linkages other than four-bar linkages can perform a similar
function. For example, another embodiment of a manipulator
constructed in accordance with the present invention is shown in
FIGS. 17-23. The embodiment of the invention shown in FIGS. 17-23
functions in the same manner as the embodiment shown for example in
FIG. 7, however, instead of using two parallel four bar linkages
that are linked together the embodiment of the invention shown in
FIGS. 17-23 utilizes two parallel gear linkage mechanisms
(referenced herein as first and second parallel gear linkage
mechanisms).
[0081] Each of the gear linkage mechanisms includes a vertical link
150, 151. The vertical links 150, 151 are parallel to each other
and, in this case, are identical. The lower end of the vertical
link 150 of the first gear linkage mechanism is supported by a
lower horizontal rod 152 for pivoting about an axis 170. The lower
horizontal rod 152 is, in turn, pivotably supported by a base 154
for pivoting about an axis 171 perpendicular to and intersecting
axis 170. In a similar manner, the lower end of the vertical link
151 of the first gear linkage mechanism is supported by a lower
horizontal rod 153, which is parallel to the lower horizontal rod
152 of the first gear linkage mechanism, for pivoting about an axis
172 (which is parallel to axis 170). The lower horizontal rod 153
is pivotably supported by the base 154 for pivoting about an axis
173 which is parallel to axis 171 and intersects axis 172. The base
154 is shown mounted on a support 58 like the one illustrated in
FIG. 9, but the manipulator may be supported in any other
convenient manner, such as in the ways described with respect to
FIG. 9.
[0082] The upper end of the vertical link 150 of the first gear
linkage mechanism is pivotable with respect to an upper horizontal
rod 155, which is parallel to the lower horizontal rod 152 of the
first gear linkage mechanism, for pivoting about an axis 174, which
is parallel to axis 170. Again, in a similar manner, the upper end
of the vertical link 151 of the second gear linkage mechanism is
pivotable with respect to an upper horizontal rod 156, which is
parallel to the lower horizontal rod 155, for pivoting about an
axis 176, which is parallel to axis 172. The two upper horizontal
rods 155 and 156 are pivotably connected to an upper crosspiece 157
which functions as an upper connector link (similar to the upper
connector link 346 of the FIG. 7 embodiment) between the two gear
linkage mechanisms. The upper horizontal rod 155 of the first gear
linkage mechanism is pivotable with respect to the upper crosspiece
157 for pivoting about axis 175, which is parallel to axis 171. The
upper horizontal rod 156 of the second gear linkage mechanism is
pivotable with respect to the upper crosspiece 157 for pivoting
about axis 177, which is parallel to axis 173.
[0083] The first gear linkage mechanism further includes a yoke 160
which is parallel to the lower horizontal rod 152. The yoke 160 is
pivotably connected to the vertical link 150 between its upper and
lower ends for pivoting about axis 180, which is parallel to axis
170. The second gear linkage mechanism also includes a yoke 161
which is parallel to the yoke 160 of the first gear linkage
mechanism. The yoke of the second gear linkage mechanism is
pivotably connected to the vertical link 151 between its upper and
lower ends for pivoting about an axis 182 which is parallel to axis
172. A lower crosspiece 162, which is parallel to the upper
crosspiece 157, extends between and is pivotably connected to the
yokes 160 and 161. Like the upper crosspiece 157, the lower
crosspiece functions as a connector link between the two gear
linkage mechanisms (similar to the lower connector link 348 of the
FIG. 7 embodiment). The lower crosspiece 162 is pivotable with
respect to the yoke 160 of the first gear linkage mechanism about
axis 181, which is parallel to axis 171. Similarly, the lower
crosspiece 162 is also pivotable with respect to the yoke 161 of
the second gear linkage mechanism about axis 183, which is parallel
to axis 173. The upper and lower crosspieces 157, 162 constrain the
vertical links 150, 151 of the two gear linkage mechanisms such
that the vertical links remain in parallel relation as they
respectively pivot about axis 171 and axis 173.
[0084] For supporting a tool 166, the manipulator illustrated in
FIGS. 17-23 includes a tool holder link 165 which is connected to
the two gear linkage mechanisms via extended portions 158, 163 of
the upper and lower crosspieces. Specifically, the extended portion
158 of the upper crosspiece 157 has a yoke 159 at its free end. The
yoke 159 is pivotably connected to the extended portion 158 for
pivoting about an axis 184, which is parallel to axis 171. The yoke
159 is also pivotably connected to the tool holder link 165 for
pivoting about an axis 185 which is perpendicular to axis 184. The
extended portion 163 of the lower crosspiece 162 extends parallel
to the extended portion 158 of the upper crosspiece and pivotally
supports a yoke 164 at its free end for rotation about axis 186,
which is parallel to axis 184. The yoke 164 is also pivotably
connected to the tool support link 165 for pivoting about axis 187,
which is perpendicular to axis 186 and parallel to axis 185.
[0085] The upper horizontal rod 155, 156 of each gear linkage
mechanism is constrained to move in parallel relation to the lower
horizontal rod 152 and 153 of each mechanism by a gear train
comprising an odd number of gears. In the illustrated embodiment,
each gear linkage mechanism includes three gears 200-202, 205-207.
On the vertical link 150 of the first gear linkage mechanism, a
first lower gear 200 is secured to the lower horizontal rod 152.
The lower gear 200 is concentric with respect to axis 170 so that
the vertical link 150 can rotate with respect to the lower gear 200
about axis 170. A second upper gear 201 is secured to the upper
horizontal rod 155 concentrically with axis 174 and is rotatable
with respect to the vertical link 150 about axis 174. A third
intermediate gear 202 is pivotably mounted on the vertical link 150
between and in mesh with the upper and lower gears 201 and 202. The
rotational axis of the intermediate gear 202 is shown coinciding
with axis 180, but the location of its rotational axis is not
critical. Lower, upper and intermediate gears 205-207 are mounted
on the vertical link 151 of the second gear linkage mechanism in
the same manner. The reduction ratios of the gears are selected so
that, for example, when the vertical link 150 of the first gear
linkage mechanism pivots with respect to the lower horizontal rod
152 about axis 170 in a first rotational direction by an angle ox,
the upper horizontal rod 155 will rotate with respect to link 150
about axis 174 in the opposite rotational direction by the same
angle .alpha.. Thus, the lower and upper horizontal rods 152, 155
of the first gear linkage mechanism remain parallel to each other.
The reduction ratios of the gears 205-207 for the second gear
linkage mechanism are selected in a similar manner.
[0086] As shown in FIG. 19, which is a side elevation of the
manipulator of FIG. 17 pivoted backwards from the position shown in
FIG. 17, pivoting the vertical links of the two gear linkage
mechanisms about axes 170 and 172 causes the tool holder link 165
and the tool 166 to pivot at a virtual pivot point 192 about an
axis 190 spaced from a plane containing axes 171 and 172. In this
respect, the manipulator shown in FIG. 17 functions similar to the
embodiment shown in FIG. 2 with the vertical links 150, 152 of the
parallel gear linkage mechanisms functioning as a single link and
the gear trains performing the function of maintaining the upper
and lower horizontal rods in parallel relation. When the vertical
links 150 and 151 are simultaneously pivoted side-to-side about
axes 171 and 173, as shown, for example, in FIGS. 21-23, the tool
holder link 165 and the tool 166 pivot at the virtual pivot point
192 about an axis 191 which is perpendicular to and intersects axis
190 at the virtual pivot point 192. Thus, the tool 166 can be
pivoted with two rotational degrees of freedom about the virtual
pivot point 192. When performing the side-to-side movement, the
manipulator can be considered like the kinematic model of FIG. 7,
with the vertical links 150 and 151 functioning like links 41 and
42 of FIG. 7, the upper and lower crosspieces 157 and 162
functioning like links 43 and 44 of FIG. 7, the extended portion of
the upper crosspiece 158 and its yoke 159 functioning like link 51
of FIG. 7, the extended portion of the lower crosspiece 163 and its
yoke 164 functioning like link 52 of FIG. 7, and the tool holder
link 165 functioning like link 53 of FIG. 7. As will be
appreciated, the manipulator of FIGS. 17-23 can be driven by hand
or by a motor or other actuator in a manner similar to that
described with respect to FIG. 16.
[0087] In FIGS. 17-23, the upper and lower gears 200, 201, 205, and
206 of the two gear linkage mechanisms are in the form of sectors
of a circle. Each of the intermediate gears 202 and 207 is in the
form a complete circle. However, the upper and lower gears may also
be completely circular, and the intermediate gears 202 and 207 may
each comprise sectors instead of a complete circle. In the
illustrated embodiment, the gears of each gear train have the same
diameter. However, the gears can have different diameters as long
as the rotational angle of the upper gear 201 and 206 of each gear
linkage mechanism is equal and opposite to the rotational angle of
the lower gears 200 and 205 of each gear linkage mechanism when the
vertical links 150 and 151 rotate with respect to the lower gears.
For example, the upper and lower gears may have the same diameter,
and the intermediate gear may have a different diameter. In
addition, the number of gears on each link is not limited to three.
In general, any odd number of gears greater than or equal to three
can perform the desired function.
[0088] Mechanisms other than gears can be used to constrain, for
example, the upper and lower horizontal rods 155 and 152 of the
manipulator shown FIG. 17 to move in parallel relation. For
example, the gears can be replaced by rollers that are in rolling
contact with each other. Alternatively, the intermediate gear 202
on the vertical link may be omitted, and the upper and lower gears
can be replaced by sprockets 210 connected to each other by a chain
211 so as to produce a parallel chain linkage mechanism, as shown
in FIG. 24, or by pulleys 215 connected to each other by a belt or
cable 216 so as to produce a parallel mechanical belt or cable
linkage mechanism, as shown in FIG. 25. In FIG. 24, a lower
sprocket 210 is secured to the lower horizontal rod 152, 153 of
each parallelogram mechanism, and an upper sprocket 210 is secured
to the upper horizontal rod 155, 156 of each parallelogram
mechanism. The lower end of the vertical link 150, 151 of each
parallelogram mechanism is pivotable with respect to the
corresponding lower sprocket 210, and the upper end of the vertical
link 150, 151 is pivotable with respect to the corresponding upper
sprocket 210. In FIG. 25, a lower pulley 215 is the lower
horizontal rod 152, 153 of each parallelogram mechanism, and an
upper pulley 215 is secured to the upper horizontal rod 155, 156 of
each parallelogram mechanism. The lower end of the vertical link
150, 151 of each parallelogram mechanism is pivotable with respect
to the corresponding lower pulley 215, and the upper end of the
vertical link 150, 151 is pivotable with respect to the
corresponding upper pulley 215.
[0089] With the manipulator embodiment shown in FIG. 17, the pivot
axes 170, 172, 174, 176, 180, and 182 associated with the vertical
link of each parallelogram mechanism lie in the same plane, so the
virtual pivot point 192 is aligned with a plane containing axes 185
and 187. A variation of the FIGS. 17-23 embodiment is shown in
FIGS. 26 and 27. With the embodiment of the invention shown in
FIGS. 26 and 27, the vertical links 150 and 151 of FIG. 17 have
been replaced by vertical links 220, 221 which have a shape such
that axes 180 and 182 are spaced from a plane containing the other
rotational axes 170, 172, 174, and 176 associated with the vertical
links. The arrangement of the various links and rods is otherwise
the same as in FIG. 17. Similar to the embodiment shown in FIG. 6,
this shape of the vertical links 220 and 221 enables the virtual
pivot point 192 to be spaced from a plane containing the axes 185
and 187 defined by the pivotal connections of the yokes 159, 164 of
the extended portions 158, 163 of the upper and lower crosspieces
157, 162 to the tool holder link 165. Accordingly, the tool 166 can
be mounted on the tool holder link 165 in a location other than a
plane containing axes 185 and 187 and still contact the virtual
pivot point 192. For example, the tool 166 can be mounted such that
it is spaced forward of the plane containing axes 185 and 187 so
that it does not interfere with imaging operations and where the
yokes 159 and 164 or other portions of the manipulator do not
interfere with movement of the tool 166.
[0090] In accordance with a further aspect of the present
invention, the manipulator can include a tool holder 410 for
holding and moving a tool with one or more degrees of freedom while
minimizing contact between the tool holder and the tool. As stated
above, a tool which is supported by a manipulator according to the
present invention can be selected from a wide variety of devices,
both for medical and non-medical purposes. FIG. 28 illustrates a
portion of a manipulator according to the present invention having
the structure shown in FIG. 26 which includes a tool holder 410
configured to hold a biopsy needle 412. The tool holder 410 is
mounted on the link 165 and can translate the needle 412 in its
lengthwise direction with respect to the link 165.
[0091] To this end, as shown in FIGS. 28-30, the tool holder 410
includes a cartridge 414 having a movable carriage 416 which can
engage the proximal end of the needle 412 and can move in the
lengthwise direction of the needle to translate it toward or away
from a patient. The cartridge 414 is detachably mounted on a drive
unit 420 which contains a motor or other drive mechanism which can
be operatively coupled to the carriage 416 to translate the
carriage in the lengthwise direction of the needle 412. The drive
unit 420 includes a pair of aligned shafts or axles 422 which are
pivotably supported by a yoke 424 secured to link 165. The yoke 424
includes a motor or other drive mechanism which can controllably
pivot the drive unit 420 about the rotational axes of the axles 422
to a desired angle. However, when the tool holder 410 is used with
a manipulator according to the present invention, the motor is
typically not operated so that the drive unit 420 remains at a
constant angle with respect to the yoke 424, with the longitudinal
axis of the needle 412 aligned with the virtual pivot point 192 of
the manipulator.
[0092] The illustrated tool holder 410 is just one example of many
possible devices for supporting a needle, but it is particularly
advantageous because it minimizes the number of components which
are subject to contamination during a medical procedure using the
needle 412. In particular, the only portion of a tool holder
according to the present invention which comes into direct contact
with a needle or other medical tool is the replaceable cartridge.
The motors for translating the carriage 416 or for rotating the
drive unit 420 are protected from contamination, so the drive unit
and the yoke 424 typically do not need to be sterilized between
uses. On the other hand, the cartridge 414 and the needle 412,
which may be subject to contamination, can be readily replaced as a
single unit after a single use, to be either sterilized or
discarded. The cartridge does not require high precision for its
manufacture nor does it require high strength, so it can be
inexpensively manufactured to enable it to be economically
discarded, if desired, after a single use. The other portions of
the tool holder are substantially free from contamination, so they
can be reused with a new cartridge without having to be sterilized
between uses.
[0093] As shown in FIGS. 33-35, the cartridge 414 includes an
elongated carriage guide 426 along which the carriage is movable in
a linear path in a lengthwise direction of the guide. The
illustrated carriage guide 426 has a generally U-shaped transverse
cross section with two elongated guide flanges 428 extending
transversely from its upper end as shown in FIG. 35. The carriage
guide 426, however, may have any desired shape which enables it to
guide the carriage 416. An elongated slot 430 through which a drive
pin 432 of the drive unit 420 can pass extends in the lengthwise
direction of the bottom surface of the carriage guide 426. An end
plate 434 is secured to the lower end (the end closest to a patient
during use) of the carriage guide 426 as shown in FIGS. 33 and
34.
[0094] The end plate 434 includes a needle guide for guiding a
portion of the needle 412 as it translates along the carriage guide
426. The illustrated needle guide comprises a notch 436 formed in
the end plate 434 through which the needle 412 can slidably pass.
The notch 436 may be equipped with a retainer such as a clip 438
which can pivot between an open position in which the needle 412
can be easily inserted into or removed from the notch 436 and a
closed position in which the clip 438 prevents the removal of the
needle 412 from the notch 436.
[0095] The carriage 416 can have any shape which enables it to
translate along the carriage guide 426 while engaging a needle 412
or other medical tool. The illustrated carriage 416 has a pair of
flanges 440 at its open end extending in its lengthwise direction
which are shaped to fit around the guide flanges 428 on the
carriage guide 426 to permit the carriage 416 to slide along the
carriage guide 426 along a linear path. The carriage 416 can engage
the needle 412 so as to be capable of exerting a drive force on the
needle 412 in its lengthwise direction to insert the needle 412
into or retract it from a patient's body.
[0096] The manner in which the carriage 416 engages the needle 412
can be chosen in accordance with the structure of the needle. As
shown in FIG. 33, the illustrated needle 412 is a commercially
available introducer needle including an elongated hollow shank 442
and an engaging portion in the form of an enlarged head 444 molded
around or otherwise secured to the proximal end (the end remote
from a patient) of the shank. The illustrated carriage 416 is
adapted to hold the needle 412 by its head 444. The carriage 416
includes a recess 446 which is sized to receive the head 444 of the
needle 412. The lengthwise end walls 448 of the recess 446 can
press against the end faces of the head 444 of the needle 412 to
exert a force on the head in the lengthwise direction of the
needle. Alternatively, the side walls of the recess 446 may fit
snugly around the head 444 to transmit a force to the head in the
longitudinal direction of the needle 412 by friction.
[0097] A retainer in the form of a clip 450 on the carriage 416 can
be pivoted between an open position shown in FIG. 33 in which the
needle 412 can be installed on or removed from the carriage and a
closed position in which the clip 450 fits over the head 444 of the
needle 412 to resist removal of the needle. One of the end walls
448 of the carriage 416 includes a notch 452 communicating with the
recess 446 through which the shank 442 of the needle 412 can pass.
The carriage 416 may hold the needle 412 in any other suitable
manner. For example, it may include jaws or fingers which can grasp
either the shank 442 or the head 444 of the needle 412. As another
example, if the head 444 of the needle 412 has a varying outer
diameter, a reduced diameter portion of the head may be disposed in
the notch 552, and portions of larger diameter adjoining the
reduced diameter portion may be disposed outside of the notch on
either side of it to prevent lengthwise movement of the needle 412
with respect to the carriage 416, with one of the larger diameter
portions disposed in the recess 446 and the other disposed outside
the recess. If the needle 412 is intended to house another member,
such as an obturator, the recess 446 may be made large enough to
receive a head or other portion of the member housed in the
needle.
[0098] As will be appreciated by those skilled in the art, when a
different type of tool is being held by the tool holder 410, the
carriage 416 may be modified to engage the tool in a different
manner from that shown in the figures. However, the illustrated
arrangement can be used for any tool having an elongated shank and
an enlarged engagement portion, such as a head, hub, collar,
flange, or knob attached to the shank. Moreover, the cartridge can
be adapted to permit the tool to be released after the tool is set
in a particular position.
[0099] The cartridge 414 is preferably readily detachable from the
drive unit 420 to permit the cartridge to be easily installed and
replaced. Any convenient method of attaching the cartridge 414 to
the drive unit 420 can be employed. In the illustrated cartridge
414, the end plate 434 is equipped with a hole 454 through which an
engagement pin 456 of the drive unit 420 (FIG. 31) can pass. An
elastically deformable clip 460 which can detachably engage a
flange 458 on the opposing end of the drive unit 420 (FIGS. 31 and
32) is mounted on the opposite end of the carriage guide 426.
[0100] In order to prevent the cartridge 414 from being reused with
more than one patient by simply replacing the needle 412 without
the cartridge being sterilized, the cartridge may be structured so
that a needle cannot be removed from the cartridge without
rendering the cartridge unusable. For example, one or both of the
clips 438 and 450 for retaining the needle 412 in the cartridge 414
may engage the cartridge when the clip is in its closed position in
a manner such that a portion of the clip or a portion of the
cartridge breaks off when the clip is opened, making it impossible
to again secure the clip in a closed position and secure the needle
to the cartridge. Such a breakable portion may be in the form of a
flange, a claw, a head, etc., which is snap-engageable with another
member when the clip is in its closed position and which breaks off
when the clip is opened.
[0101] The drive unit 420 can have any structure which enables it
to exert a drive force on the carriage 416 in a lengthwise
direction of the needle 412 to cause the carriage to translate
along the carriage guide 426. As shown in FIGS. 31-32, the
illustrated drive unit 420 includes a frame 462 which supports a
drive mechanism. The illustrated drive mechanism includes a lead
screw 464 which engages with a movable nut 465 having a drive pin
432 projecting from its upper surface for detachable engagement
with the carriage 416. The carriage 416 may engage the pin 432 on
the drive unit 420 in any convenient manner. In the illustrated
embodiment, the carriage 416 includes a recess 466 in its bottom
surface for engagement with the pin 432. The nut 465 can be
prevented from rotating as it translates along the lead screw 464
by the sides of the frame 462 or by a guide member, such as a rod,
slidably engaging with the nut 465. The lead screw 464 can be
rotated about its axis by any suitable drive source, such as by an
electric motor 468 drivably connected to the lead screw 464 by a
gear unit 470. When the motor 468 is driven, the lead screw 464 is
rotated about its axis to translate the nut 465 along the lead
screw 464 and move the carriage 416 of the cartridge 414 either
toward or away from a patient's body. A few examples of other
suitable drive mechanisms for translating the carriage 416 along
the carriage guide 426 include a belt and pulley drive, a linear
motor, or a pneumatic or hydraulic cylinder.
[0102] The moving parts of the drive unit 420 are preferably
enclosed to protect them from contamination and to prevent them
from contaminating a patient. As shown in FIG. 30, the illustrated
drive unit 420 includes a cover 472 which surrounds all the moving
parts except for the pin 432 of the nut 465, which extends through
an elongated slit 474 in the top surface of the cover parallel to
the lead screw 464. The portion of the cover 472 in which the slit
474 is formed may be made of a flexible material so that the slit
is substantially closed except in the region immediately
surrounding the pin 432 where the pin forces the slit 474 open.
[0103] The drive unit 420 is preferably pivotably supported by the
yoke 424 for pivoting about a pitch axis which is transverse (e.g.,
perpendicular) to the axis of the needle 412. The illustrated yoke
434 includes a pair of legs 476 separated by a cavity 478 for
receiving the drive unit 420 when the drive unit is in an initial
position ash shown in FIG. 30. The drive unit 420 may be pivoted
about the pitch axis manually, or the yoke 424 or the drive unit
may be equipped with a drive mechanism for exerting a rotary drive
force on the drive unit about the pitch axis. For example, the
illustrated yoke 424 is equipped with an electric motor 480 (FIGS.
29 and 30) which is operatively connected to one of the axles 422
of the drive unit 420 by a gear unit, such as a worm gear unit
including a worm 482 secured to the output shaft of the motor 480
and a worm gear 484 secured to the axle 422. When the motor 480 is
operated, the entire drive unit 420 can be pivoted about the pitch
axis to a desired angle. In FIG. 29, the drive unit 420 is shown
pivoted clockwise about the pitch axis so that the proximal end of
the needle 412 is raised above the yoke 424, but the drive unit may
be rotated in the opposite direction so that the proximal end of
the needle 412 is positioned below the yoke. The drive unit can
have any desired range of rotation about the pitch axis. The
greater the range of rotation about the pitch axis, the less the
entire tool holder 410 needs to be moved to obtain a desired angle
of the needle 412 with respect to a patient's body. In the present
embodiment, the drive unit can be rotated about the pitch axis by
approximately .+-.115.degree. from its initial position (i.e., with
the needle parallel to the longitudinal axis of the yoke), but a
greater range of rotation may be employed. For example, the drive
unit 420 may be rotatable by 360.degree. around the pitch axis.
[0104] In some situations, it may be convenient to dispense a drug
or other substance to a patient during use of the needle 412.
Therefore, the cartridge 414 may be equipped with one or more
devices for dispensing a local anesthetic, an antiseptic agent, or
other substance to a patient when the needle 412 is being inserted
into the patient's body. As shown in FIG. 33, the illustrated
cartridge 414 is equipped with first and second dispensing units
486 and 488 disposed on opposite widthwise sides of the carriage
guide 426 near the end plate 434. The dispensing units, however,
can be mounted in any convenient location on the cartridge, drive
unit or yoke. The first dispensing unit 486 comprises an applicator
for applying a liquid to the skin of a patient, while the second
dispensing unit 488 comprises an injector for administering a
percutaneous injection of a substance to a patient.
[0105] FIGS. 36 and 37 are schematic cross-sectional views of
examples of the two dispensing units 486 and 488, respectively. As
shown in FIG. 36, the first dispensing unit 486 includes a
reservoir 490 containing a liquid 492 to be applied to a patient's
skin. An absorbent wick 494 extends from the interior of the
reservoir 490 where it contacts the liquid 492 through an opening
495 of the reservoir 490 to its exterior. When not in use, the
outer end of the wick 494 may be covered by a cap or other suitable
member to prevent it from drying out. The liquid 492 is drawn by
the wick 494 to the outer end of the wick, which can be placed
against a patient's skin to transfer the liquid 492 from the
reservoir 490 to the skin, and the tool holder 410 can be moved
along a desired path to swab the patient's skin with the liquid.
The liquid 492 in the reservoir 490 can be any substance suitable
for topical application. For example, it may be PVD iodine or other
antiseptic agent for use in cleansing a patient's skin in the
region into which the needle 412 is to be inserted. Devices other
than a wick 494 can be used to transfer liquid 492 from the
reservoir 490 to the patient's skin in a gradual manner, such as a
roller ball similar to that used in a ballpoint pen or a
spring-loaded valve which can open when pressed against the
patient's skin.
[0106] As shown in FIG. 37, the second dispensing unit 488 includes
a housing having a first chamber 496 containing a first movable
piston 497 and a second chamber 498 adjoining the first chamber 496
and containing a second movable piston 499 coupled to the first
piston 497 so that the two pistons can move together. The first
chamber 496 is equipped with a fluid port 500 through which a drive
fluid can be introduced under pressure into the first chamber. The
second chamber 498 is equipped with an orifice 502 opening onto the
exterior of the housing through which a fluid to be administered to
a patient can be discharged under pressure. When not in use, the
orifice 502 may be closed by a cap, a stopper, sealing tape, or
other suitable member to prevent fluid from leaking from the second
chamber 498. The drive fluid for driving the first piston 497 can
be either a gas or a liquid, a few examples of suitable drive
fluids being air, CO.sub.2, and water.
[0107] Prior to use, the second chamber 498 is filled with a fluid
(usually a liquid but possibly a gas) to be administered to a
patient, which may be any substance suitable for percutaneous
injection during a medical procedure involving a needle 412 or
other medical tool. For example, the fluid may be Lidocaine or
other local anesthetic for preventing pain in the region into which
the needle is to be inserted. To inject the fluid into a patient,
the cap or other cover is removed from the orifice 502, and the
tool holder 410 is moved to a position in which the orifice is
pressed against or is in close proximity to the patient's skin. The
drive fluid is then introduced under pressure into the right side
of the first chamber 496 through fluid port 500 to drive the first
and second pistons 497 and 499 to the left in FIG. 38. As the
second piston 499 moves to the left, it discharges the fluid
through the orifice 502 and through the patient's skin into his
body.
[0108] The tool holder 41 0 of the present invention can have an
extremely compact design, so it can support and manipulate a
medical tool inside tight spaces in which it would be difficult or
impossible for a human operator to position a tool or in
environments which would be unsafe for a human operator. In
particular, the manipulator can hold a medical tool with respect to
a patient inside medical imaging equipment, such as CT (computer
tomography) equipment, conventional x-ray equipment, or magnetic
resonance imaging equipment, which equipment often has a very small
clearance surrounding a patient's body during imaging. Therefore,
the tool holder enables the position of a medical tool with respect
to a patient to be adjusted while imaging is taking place and makes
it unnecessary to remove the patient from the imaging equipment
each time the position of the tool needs to be adjusted. For this
reason, the medical tool can be positioned quickly and accurately,
enabling a medical procedure to be performed with the tool
efficiently and economically with less stress on the patient. The
ability of the tool to be rapidly positioned is particularly
advantageous when the tool is being positioned in or near the
patient's chest and the patient is holding his breath.
[0109] As will be appreciated, the tool holder 410 can be
configured to hold a wide variety of medical tools both for
therapeutic and diagnostic purposes, a few examples of which are
biopsy needles, biopsy guns, catheters, various probes including
cryo probes and radio frequency probes, lasers, laser hyperthermia
devices, cameras, and needles for administering various substances,
such as biotherapeutic agents, alcohol, or radioactive pellets, to
the interior of a patient's body. In addition to tools which are
inserted into a patient's body, the tool holder can be used to hold
tools which are normally utilized on a patient's exterior.
Moreover, the tool holder can be operated in a master-slave mode, a
fully robotic mode, or a semi-robotic mode in which some of the
motions of the tool holder are controlled by input commands from an
operator and other motions are controlled automatically.
[0110] All of the references cited herein, including patents,
patent applications, and publications, are hereby incorporated in
their entireties by reference.
[0111] While this invention has been described with an emphasis
upon preferred embodiments, it will be obvious to those of ordinary
skill in the art that variations of the preferred embodiments may
be used and that it is intended that the invention may be practiced
otherwise than as specifically described herein. Accordingly, this
invention includes all modifications encompassed within the spirit
and scope of the invention as defined by the following claims.
* * * * *