System and method for releasably holding a surgical instrument

The invention is directed to a system and method for releasably holding a surgical instrument (14), such as an endoscopic instrument configured for delivery through a small percutaneous penetration in a patient. The instrument comprises an elongate shaft (100) with a pair of mounting pins (116) laterally extending from the shaft between its proximal and distal ends. An instrument holder comprises a support having a central bore (202) and an axially extending slot (204) for receiving the instrument shaft and the mounting pins. A pair of locking slots (206) are cut into the support transversely to and in communication with the axial slot so that the mounting pins can be rotated within the locking slots. The instrument support further includes a latch assembly for automatically locking the mounting pins within the locking slots to releasably couple the instrument to the instrument holder. With this twist-lock motion, the surgeon can rapidly engage and disengage various instruments from the holder during a surgical procedure, such as open surgery, laparoscopy or thoracoscopy.

BACKGROUND OF THE INVENTION 
This invention relates to surgical manipulators and more particularly to 
robotic assisted apparatus for use in surgery. 
In standard laparoscopic surgery, a patient's abdomen is insufflated with 
gas, and trocar sleeves are passed through 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 such as clamps, graspers, 
scissors, staplers, and needle holders. The working tools are similar to 
those used in conventional (open) surgery, except that the working end of 
each tool is separated from its handle by an approximately 12-inch long 
extension tube. To perform surgical procedures, the surgeon passes 
instruments through the trocar sleeves and manipulates them inside the 
abdomen by sliding them in and out through the sleeves, rotating them in 
the sleeves, levering (e.g., pivoting) the sleeves in the abdominal wall, 
and actuating end effectors on the distal end of the instruments. 
In robotically-assisted and telerobotic surgery (both open surgery and 
endoscopic procedures), the position of the surgical instruments is 
controlled by servo motors rather than directly by hand or with fixed 
clamps. The servo motors follow the motions of a surgeon's hands as he/she 
manipulates input control devices at a location that may be remote from 
the patient. Position, force, and tactile feedback sensors may be employed 
to transmit position, force, and tactile sensations from the surgical 
instrument back to the surgeon's hands as he/she operates the telerobotic 
system. 
The servo motors are typically part of an electromechanical device that 
supports and controls the surgical instruments that have been introduced 
directly into an open surgical site or through trocar sleeves into the 
patient's abdomen becomes a body cavity. During the operation, the 
electromechanical device or instrument holder provides mechanical 
actuation and control of a variety of surgical instruments, such as tissue 
graspers, needle drivers, etc, that each perform various functions for the 
surgeon, i.e., holding or driving a needle, grasping a blood vessel or 
dissecting tissue. 
This new method of performing telesurgery through remote manipulation will 
create many new challenges. One such challenge is that different surgical 
instruments will be attached and detached from the same instrument holder 
a number of times during an operation. In laparoscopic procedures, for 
example, the number of entry ports into the patient's abdomen is generally 
limited during the operation because of space constraints as well as a 
desire to avoid unnecessary incisions in the patient. Thus, a number of 
different surgical instruments will typically be introduced through the 
same trocar sleeve during the operation. Likewise, in open surgery, there 
is typically not enough room around the surgical site to position more 
than one or two surgical manipulators, and so the surgeon's assistant will 
be compelled to frequently remove instruments from the holder and exchange 
them with other surgical tools. 
What is needed, therefore, is an improved system and method for releasably 
coupling a surgical instrument to an instrument holder. The system should 
be configured to quickly and easily engage and disengage the instrument 
from the holder to minimize the instrument exchange time during endoscopic 
surgery. Preferably, the system is part of an electromechanical device 
that can be coupled to a controller mechanism to form a telerobotic system 
for operating the surgical instrument by remote control. 
SUMMARY OF THE INVENTION 
According to the invention, a system and method provide for releasably 
holding a surgical instrument during conventional open surgery or 
endoscopic procedures, such as laparoscopy. The instrument comprises an 
elongate shaft with proximal and distal ends and a mounting means having a 
protrusion extending radially from the shaft between the proximal and 
distal ends. An instrument holder comprises a support having a body with 
an axial passage for receiving the instrument shaft and a first hole in 
communication with the axial passage for receiving the protrusion. A 
second hole is cut into the body transversely to and in communication with 
the first hole so that the protrusion can be rotated within the second 
hole. To prevent the instrument from being accidently twisted and thereby 
disengaged from the instrument holder during surgery, the holder further 
includes a locking means coupled to the body for automatically locking the 
protrusion within the second hole thereby releasably locking the 
instrument to the instrument holder. 
In a preferred configuration, the protrusion of the mounting means 
comprises a pair of opposing arms, such as mounting pins, extending 
outward from the instrument shaft. The first hole is an axially extending 
slot for receiving the mounting pins and the second hole is a 
perpendicular locking slot having a first portion aligned with the axial 
slot and a second portion extending circumferentially around the body of 
the instrument support. With this configuration, the mounting pins can be 
slid through the axial slot and rotated into the locking slot to attach 
the instrument to the holder. The instrument can be removed by performing 
the same two steps in reverse order. With this twist-lock motion, the 
surgeon can rapidly engage and disengage various instruments from the 
instrument holder during a surgical procedure. 
The locking means preferably comprises a releasable latch assembly for 
locking the mounting pins to the instrument holder. The latch assembly 
includes a spring-loaded plunger coupled to a latch that normally locks 
the instrument in place by capturing the mounting pin in the locking slot. 
The plunger has a button extending outward from the instrument holder for 
moving the latch away from the locking slot. The button can be depressed 
manually or automatically to release the mounting pins and allow 
instrument exchange when the instrument is easily accessible to the 
surgeon. 
The invention is particularly useful for releasably holding an endoscopic 
instrument configured for introduction through a small percutaneous 
penetration into a body cavity, e.g., the abdominal or thoracic cavity. To 
that end, the instrument preferably includes an end effector, such as a 
pair of jaws, coupled to the distal end for engaging a tissue structure 
within the body cavity. To actuate the end effector, the instrument has a 
second pair of arms, such as actuator pins, laterally extending from the 
shaft and operatively coupled to the end effector. Preferably, the 
actuator pins are axially displaceable with respect to the shaft to 
actuate the end effector (e.g., open and close the jaws). The instrument 
holder further includes an actuator driver releasably coupled to the 
actuator arms and to an external driver for actuating the end effector. 
The actuator driver preferably includes a twist-lock interface having 
transverse slots similar to that described for the instrument support so 
that the instrument can be simultaneously engaged or disengaged from both 
the instrument support and the actuator driver. 
Other features and advantages of the invention will appear from the 
following description in which the preferred embodiment has been set forth 
in detail in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings in detail, wherein like numerals indicate like 
elements, a manipulator assembly 2 is illustrated according to the 
principles of the invention. Manipulator assembly 2 generally includes an 
instrument holder 4 removably mounted to a base 6 and a drive assembly 7 
for manipulating a surgical instrument 14 releasably coupled to instrument 
holder 4. 
Referring to FIG. 1, base 6 comprises a frame 16 having proximal and distal 
elongate support members 17, 19 and first and second ball-spline shafts 
18, 20 rotatably coupled to support members 17, 19 via bearings 22. Frame 
16 further includes a support bracket 24 for attaching manipulator 
assembly 2 to a remote center positioner 300, as discussed in more detail 
below (see FIG. 9). Drive assembly 7 comprises first, second and third 
drives 8, 10, 12, which are mounted to frame 16 and configured to provide 
three degrees of freedom to surgical instrument 14. In the preferred 
embodiment, first drive 8 rotates instrument 14 around its own axis, 
second drive 10 actuates an end effector 120 on the distal end of 
instrument 14 and third drive 12 axially displaces instrument 14 with 
respect to frame 16. Of course, it will be readily recognized by those 
skilled in the art that other configurations are possible. For example, 
assembly 2 may include additional drives for providing additional degrees 
of freedom to surgical instrument 14, such as rotation and flexion of an 
instrument wrist. 
First drive 8 comprises a rotation drive motor 26 fixed to frame 16 and 
coupled to first shaft 18 by a drive belt 28 for rotating first shaft 18 
with respect to frame 16. Second drive 10 comprises a gripper drive motor 
30 fixed to frame 16 and coupled to second shaft 20 by a drive belt 32 for 
rotating second shaft 20 with respect to frame 16. Third drive 12 
comprises a vertical drive motor 34 coupled to instrument holder 4 via a 
drive belt 36 and two pulleys 38 for axially displacing instrument holder 
4 with respect to frame 16. Drive motors 26, 30, 34 are preferably coupled 
to a controller mechanism via servo-control electronics (not shown) to 
form a telerobotic system for operating surgical instrument 14 by remote 
control. The drive motors follow the motions of a surgeon's hands as 
he/she manipulates input control devices at a location that may be remote 
from the patient. A suitable telerobotic system for controlling the drive 
motors is described in commonly assigned co-pending application Ser. No. 
08/823,932 filed Jan. 21, 1992 TELEOPERATOR SYSTEM AND METHOD WITH 
TELEPRESENCE, which is incorporated herein by reference. 
The above described telerobotic servo system preferably has a servo 
bandwidth with a 3 dB cut off frequency of at least 10 hz so that the 
system can quickly and accurately respond to the rapid hand motions used 
by the surgeon. To operate effectively with this system, instrument holder 
4 has a relatively low inertia and drive motors 26, 30, 34 have relatively 
low ratio gear or pulley couplings. 
In a specific embodiment, surgical instrument 14 is an endoscopic 
instrument configured for introduction through a percutaneous penetration 
into a body cavity, such as the abdominal or thoracic cavity. In this 
embodiment, manipulator assembly 2 supports a cannula 50 on distal support 
member 19 of frame 16 for placement in the entry incision during an 
endoscopic surgical procedure (note that cannula 50 is illustrated 
schematically in FIG. 1 and will typically be much longer). Cannula 50 is 
preferably a conventional gas sealing trocar sleeve adapted for 
laparoscopic surgery, such as colon resection and Nissen fundoplication. 
As shown in FIG. 1, cannula 50 preferably includes a force sensing element 
52, such as a strain gauge or force-sensing resistor, mounted to an 
annular bearing 54 within cannula 50. Bearing 54 supports instrument 14 
during surgery, allowing the instrument to rotate and move axially through 
the central bore of bearing 54. Bearing 54 transmits lateral forces 
exerted by the instrument 14 to force sensing element 52, which is 
operably connected to the controller mechanism for transmitting these 
forces to the input control devices (not shown) held by the surgeon in the 
telerobotic system. In this manner, forces acting on instrument 14 can be 
detected without disturbances from forces acting on cannula 50, such as 
the tissue surrounding the surgical incision, or by gravity and inertial 
forces acting on manipulator assembly 2. This facilitates the use of 
manipulator assembly in a robotic system because the surgeon will directly 
sense the forces acting against the end of instrument 14. Of course, the 
gravitational forces acting on the distal end of instrument 14 will also 
be detected by force sensing element 52. However, these forces would also 
be sensed by the surgeon during direct manipulation of the instrument. 
As shown in FIG. 1, instrument holder 4 comprises a chassis 60 mounted on 
shafts 18, 20 via ball-spline bearings 62, 64 so that chassis 60 may move 
axially with respect to shafts 18, 20, but is prevented from rotating with 
shafts 18, 20. Chassis 60 is preferably constructed of a material that 
will withstand exposure to high temperature sterilization processes, such 
as stainless steel, so that chassis 60 can be sterilized after a surgical 
procedure. Chassis 60 includes a central cavity 66 for receiving surgical 
instrument 14 and an arm 68 laterally extending from chassis 60. Arm 68 is 
fixed to drive belt 36 so that rotation of drive belt 36 moves instrument 
holder 4 in the axial direction along shafts 18, 20. 
Instrument holder 4 is removably coupled to base 6 and the drive motors so 
that the entire holder 4 can be removed and sterilized by conventional 
methods, such as steam, heat and pressure, chemicals, etc. In the 
preferred configuration, arm 68 includes a toggle switch 69 that can be 
rotated to release arm 68 from drive belt 36 (FIG. 1). In addition, shafts 
18, 20 are removably coupled to bearings 22 so that the shafts can be 
axially withdrawn from support members 17, 19 of frame 16, as shown in 
FIG. 1A. To this end, the distal bearings 22 preferably include a coupling 
mechanism for allowing the removal of shafts 18, 20. As shown in FIG. 7, 
distal support member 19 includes a support collar 71 within each distal 
bearing 22 having an inner bore 72 for passage of one of the shafts 18, 
20. Each support collar 71 has an internal groove 73 and shafts 18, 20 
each have an annular groove 74 (see FIG. 1A) near their lower ends that is 
aligned with internal grooves 73 when the shafts are suitably mounted 
within frame 16 (FIG. 1). A spring clip 75 is positioned within each 
internal groove 73 to hold each shaft 18, 20 within the respective support 
collar 71. Spring clip 74 has a discontinuity (not shown) to allow removal 
of shafts 18, 20 upon the application of a threshold axial force on the 
shafts. 
To remove instrument holder 4 from base 6, the operator rotates toggle 
switch 69 to release arm 68 from drive belt 36 and removes drive belts 28, 
32 from drives 8, 10. As shown in FIG. 1A, the operator holds instrument 
holder 4 and pulls shafts 18, 20 upwards, providing enough force to 
release spring clips 75. Shafts 18, 20 will disengage from distal bearings 
22 and slide through ball-spline bearings 62, 64 so that instrument holder 
4 is disconnected from base 6. It should be understood that the invention 
is not limited to the above described means for removably coupling 
instrument holder 4 to base 6 and drive assembly 7. For example, distal 
support member 19 may be removably coupled to the rest of frame 16 so that 
the surgeon simply removes member 19 and slides holder down and off shafts 
18, 20. Proximal support member 17 may be removably coupled to frame 16 in 
a similar manner. Alternatively, the drive motors may be housed in a 
separate servo-box (not shown) that is removably attached to base 6. In 
this configuration, the servo-box would be removed from base 6 so that the 
entire base 6, together with holder 4, can be sterilized. 
The lower portion of base 6 (including distal support member 19) may also 
be sterilized to decontaminate those parts that come into contact with 
holder 4 or instrument 14 (e.g., by dipping the lower portion of base 6 
into a sterilizing bath). To facilitate this type of sterilization, shafts 
18, 20 will preferably be somewhat longer than shown in FIG. 1 so that the 
upper portion of base 6, including drive assembly 7, is disposed 
sufficiently away from holder 4 and instrument 14. In this manner, the 
surgical manipulator can be easily sterilized after a surgical procedure 
without damaging the drive motors or the electrical connections required 
for the telerobotic system. 
Instrument holder 4 further includes an instrument support 70 (see detail 
in FIG. 3A), for releasably coupling surgical instrument 14 to the 
manipulator assembly. Instrument support 70 is rotatably mounted within 
chassis 60 via mounting bearings 74 so that support 70 and the instrument 
can be rotated therein. As shown in FIG. 1, support 70 is circumscribed by 
an annular ring gear 76 having teeth that mesh with the teeth of a drive 
gear 78 mounted to first shaft 18. Drive gear 78 is configured around 
first shaft 18 such that it will rotate with first shaft 18, thereby 
rotating instrument support 70 and the surgical instrument therewith. 
Drive gear 78 is also configured to move axially with respect to first 
shaft 18 to allow axial movement of instrument holder 4 with respect to 
frame 16. 
Instrument holder 4 further includes an actuator driver 80 (see detail in 
FIG. 5) movably mounted within axial guide slots 82 on either side of 
chassis 60. Actuator driver 80 comprises a helical actuator 84 (see detail 
in FIG. 6B) having a ring gear 86 that meshes with a gripper drive gear 88 
mounted to second shaft 20. Rotation of second shaft 20 causes rotation of 
gripper drive gear 88, thereby rotating ring gear 86 and helical actuator 
84 within chassis 60. Actuator driver 80 further includes an actuator 
carriage assembly 90 (see detail in FIG. 6A) for releasably coupling an 
end effector actuator of surgical instrument 14 to instrument holder 4 
(see FIG. 2). Carriage assembly 90 is mounted within helical actuator 84 
and chassis 60 such that rotation of helical actuator 84 causes a 
corresponding axial movement of carriage assembly 90 with respect to 
chassis 60, as discussed in greater detail below. 
FIGS. 2A and 2B illustrate a specific embodiment of an endoscopic surgical 
instrument 14 capable of being operated by a motorized manipulator, such 
as manipulator assembly 2, for telerobotic surgery. Surgical instrument 14 
can be a variety of conventional endoscopic instruments adapted for 
delivery through a percutaneous penetration into a body cavity, such as 
tissue graspers, needle drivers, microscissors, electrocautery dissectors, 
etc. In the preferred embodiment, instrument 14 is a tissue grasper 
comprising a shaft 100 having a proximal end 102, a distal end 104 and a 
longitudinal axis 106 therebetween. A knurled handle 114 is attached to 
proximal end 102 of shaft 100 to facilitate manipulation of instrument 14. 
Shaft 100 is preferably a stainless steel tube having an outer diameter in 
the range of 2-10 mm, usually 4-8 mm, so as to fit within a cannula having 
an internal diameter in the range of 2-15 mm. Shaft 100 can also be 
introduced directly through a percutaneous incision in the patient. Shaft 
100 has a length selected to reach a target site in a body cavity, such as 
the abdomen, and to extend sufficiently out of the body cavity to 
facilitate easy manipulation of surgical instrument 14. Thus, shaft 100 
should be at least between 10 cm and 40 cm and is preferably between 17 cm 
and 30 cm. It should be noted that although shaft 100 is shown as having a 
circular cross-sectional shape in the drawings, shaft 100 could 
alternatively have a rectangular, triangular, oval or channel 
cross-sectional shape. 
In a specific configuration, shaft 100 includes a mounting means for 
releasably coupling surgical instrument 14 to instrument support 70 and 
first drive 8 of manipulator assembly 2. In the preferred embodiment, 
mounting means comprises a pair of opposed mounting pins 116 extending 
laterally outward from shaft 100. Mounting pins 116 are rigidly connected 
to shaft 100 and are adapted for engaging a twist-lock interface on 
instrument support 70, as discussed in detail below. It should be 
understood that the invention is not limited to a pair of opposing pins 
and mounting means can include a single mounting pin or a plurality of 
pins extending circumferentially around shaft. Alternatively, pins 116 may 
have a variety of other shapes, such as spherical or annular, if desired. 
Instrument 14 includes an end effector 120 extending from distal end 104 
for engaging a tissue structure on the patient, such as the abdomen during 
laparoscopic surgery. In the preferred embodiment, end effector 120 
comprises a pair of jaws 122, 124 that are movable between open and closed 
positions for grasping a blood vessel, holding a suture, etc. Jaws 122, 
124 preferably have transverse grooves or other textural features (not 
shown) on opposing surfaces to facilitate gripping of the tissue 
structure. To avoid the possibility of damaging the tissue to which jaws 
122, 124 are applied, the jaws may also include atraumatic means (not 
shown), such as elastomeric sleeves made of rubber, foam or surgical gauze 
wrapped around jaws 122, 124. 
To move jaws 122, 124 between the open and closed positions, instrument 14 
includes an end effector actuator releasably coupled to actuator driver 80 
and second drive 10 of manipulation assembly 2 (see FIG. 4). In the 
preferred embodiment, end effector actuator comprises a pair of opposed 
actuator pins 132 laterally protruding from axially extending slots 134 in 
shaft 100. Actuator pins 132 are coupled to an elongate rod 136 slidably 
disposed within an inner lumen 138 of shaft 100. Actuator pins 132 are 
slidable within slots 134 so that rod 136 is axially movable with respect 
to shaft 100 and mounting pins 116 to open and close jaws 122, 124, as is 
conventional in the art. Elongate rod 136 has a proximal portion 140 that 
is disposed within an inner lumen 142 within shaft 100 to prevent actuator 
pins 132 from moving in the lateral direction and to ensure that rod 136 
remains generally centered within shaft 100 during a surgical procedure. 
Jaws 122, 124 are preferably biased into the closed positioned by an 
annular compression spring 144 positioned within shaft 100 between 
actuator pins 132 and an annular disc 146 fixed to the inside surface of 
shaft 100. During endoscopic procedures, this allows the surgical team to 
introduce jaws 122, 124 through cannula 50 (or any other type of 
percutaneous penetration) and into the body cavity without getting stuck 
within cannula 50 or damaging surrounding tissue. 
FIGS. 3A, 3B and 4 illustrate a twist lock mechanism for releasably 
connecting surgical instrument 14 to manipulator assembly 2 so that 
different instruments may be rapidly changed during an endoscopic surgical 
procedure. As shown in FIG. 3A, instrument support 70 comprises an annular 
collar 200 defining a central bore 202 for receiving shaft 100 of surgical 
instrument 14. Collar 200 further defines an axially extending slot 204 in 
communication with bore 202 and sized to allow mounting and actuator pins 
116, 132 of instrument 14 to slide therethrough (see FIG. 4). Two locking 
slots 206 are cut into annular collar 200 at a transverse angle, 
preferably about 90.degree., to axially extending slot 204 (note that only 
one of the locking slots are shown in FIG. 3A). Locking slots 206 
intersect slot 204 near the center of annular collar 200 and extend 
circumferentially around bore 202, preferably about 90.degree., to allow 
rotation of both mounting pins 116 therethrough, as discussed below. 
As shown in FIGS. 3A and 8, instrument support 70 further comprises means 
for locking mounting pins 116 into locking slots 206 so that the 
instrument cannot be accidently twisted and thereby disengaged from 
instrument support 70 during surgery. Preferably, the locking means 
comprises a latch assembly having a plunger 210 slidably disposed within a 
hole 212 in collar 200, as shown in FIG. 3A. Plunger 210 comprises an 
L-shaped latch 213 coupled to a release button 214 by a rod 215 extending 
through hole 212. Plunger 210 is movable between a first position, where 
latch 213 is not disposed within locking slots 206 so that mounting pins 
116 are free to rotate therethrough, and a second position, where latch 
213 is at least partially disposed within one of the locking slots 206 so 
as to prevent rotation of mounting pins 116. Latch 213 is preferably 
biased into the second or locked position by a compression spring 216. 
Button 214 is disposed on the upper surface of support 70 for manual 
actuation by the surgeon or automatic actuation by base 6. Preferably, 
when instrument holder 4 is moved to its most proximal position (see FIG. 
1), proximal support member 17 of frame 16 depresses release switch 214 to 
move latch 213 into the first or open position. With this configuration, 
instruments can be exchanged only when the instrument holder 4 is in the 
most proximal position, where shaft 100 of instrument 14 is easily 
accessible. In addition, this prevents the accidental release of the 
instrument when its distal end has penetrated cannula 50 and is disposed 
within the body cavity. 
The intersecting axial and locking slots 204, 206 form an interface for 
releasably coupling mounting pins 116 of surgical instrument 14 to 
instrument holder 4. To insert instrument 14, the surgeon aligns mounting 
pins 116 with axial slot 204 and slides the instrument through bore 202 of 
annular collar 200 until mounting pins 116 are aligned with locking slots 
206, as shown in FIG. 4. The instrument is then rotated a sufficient 
distance, preferably about a 1/4 turn, through locking slots 206 so that 
the pins are no longer aligned with axial slot 204. When instrument 14 is 
moved distally, switch 214 is released (FIG. 1) and latch 213 moves into 
locking slots 206 to prevent mounting pins 116 from rotating back into 
alignment with axial slot 204 so that instrument 14 is secured to 
instrument support 70. It should be noted that a single mounting pin may 
be utilized with the above described configuration to lock the surgical 
instrument to the support. However, two opposing pins are preferred 
because this configuration reduces torsional forces on the inner surface 
of locking slots 206. 
As shown in FIG. 8, the locking means preferably includes a ball detent 217 
disposed within collar 200. Ball detent 217 is biased upward into one of 
the locking slots 206 by a spring 218. Ball detent 217 serves to 
temporarily capture mounting pins 116 in a position rotated about 
90.degree. from alignment with axial slot 204. This ensures that the 
mounting pins will be completely rotated into the proper position (i.e., 
out of the way of latch 213) when instrument 14 is twisted into instrument 
holder. Otherwise, when switch 214 is released, latch 213 could become 
engaged with mounting pins 216 so that the latch is unable to move 
completely into the locked position, thereby potentially causing the 
accidental release of instrument 14 during surgery. 
As shown in FIGS. 3B, 4 and 5, actuator driver 80 of instrument holder 4 
further comprises an actuator pin catch 220 for releasably holding and 
moving actuator pins 132 of instrument 14. Actuator pin catch 220 is 
constructed similarly to instrument support 70 (FIG. 3A), comprising an 
annular collar 222 that defines a bore 224 for receiving shaft 100 and an 
axially extending slot 226 for receiving actuator pins 132. A locking slot 
228 is cut into actuator pin catch 220 at a 90.degree. angle so that 
actuator pins can be rotated into the lock slot to couple actuator pins 
132 to actuator driver 66, as discussed above in reference to the mounting 
pins. It should be noted that slot 226 need not extend completely through 
collar 222 since actuator pins 132 are located distally of mounting pins 
116 (the instrument is preferably inserted jaws first). Of course, 
actuator and mounting pins 132, 116 may be reversed so that the mounting 
pins are distal to the actuator pins, if desired. 
Referring to FIG. 6A, actuator pin catch 220 is rotatably mounted on a ball 
bearing 230 in actuator carriage assembly 90. Bearing 230 allows the pin 
catch 220 to rotate freely in carriage assembly 90 while preventing 
relative axial motion. Therefore, when instrument 14 is rotated by first 
drive 8, actuator pins 132 will rotate within carriage assembly 90. 
Carriage assembly 90 further comprises two sets of axles 232 for rotatably 
supporting a pair of inner rollers 236 and a pair of outer rollers 238. As 
shown in FIG. 1, outer rollers 238 are slidably disposed within axial 
guide slots 82 of chassis 60 to prevent rotation of carriage assembly 90 
with respect to chassis 60. Inner and outer rollers 236, 238 cooperate 
with helical actuator 84 and chassis 60 of instrument holder 4 to move 
axially with respect to the holder, thereby axially moving pin catch 220 
and actuator pins 132 therewith relative to shaft 100 of instrument 14 
(which actuates jaws 122, 124, as discussed above). 
As shown in FIG. 6B, helical actuator 84 includes a central bore 240 for 
receiving carriage assembly 90 and surgical instrument 14 and two opposing 
helical tracks 242, 244 each extending circumferentially around helical 
actuator 84 (preferably slightly less than 180.degree.) for receiving 
inner rollers 236 of carriage assembly 90, as shown in FIG. 5. With outer 
rollers 238 constrained in axial guide slots 82 of chassis 60, rotation of 
helical actuator 84 causes carriage assembly 90 (and actuator pin catch 
220) to move up or down, depending on the sense of the rotation. Because 
of the symmetrical design of helical actuator 84, the actuation force 
applied by second driver 10 will not generate any effective side loads on 
instrument 14, which avoids frictional coupling with other degrees of 
freedom such as axial (third driver 12) and rotation (first driver 8). In 
the preferred embodiment, helical tracks 242, 244 have a pitch selected 
such that the mechanism can be easily back-driven, allowing grip forces to 
be sensed in a position-servoed teleoperation system. 
As shown in FIGS. 3A and 3B, instrument holder 4 further includes a pair of 
axial guide pins 250, 252 fixed to instrument support 70. Actuator pin 
catch 220 has a pair of openings 254, 256 for receiving guide pins 250, 
252. Guide pins 250, 252 prevent relative rotation between pin catch 220 
and support 70 (so that actuator and mounting pins 116, 132 can both 
rotate with the instrument) and allow axial movement relative to each 
other (so that end effector 120 can be actuated by axial movement of 
actuator pins 132). 
FIG. 9 is an elevational view of a remote center positioner 300 which can 
be used to support manipulator assembly 2 above the patient (note that 
support manipulator 2 is not shown in FIG. 8). Remote center positioner 
300 provides two degrees of freedom for positioning manipulator assembly 
2, constraining it to rotate about a point 308 coincident with the entry 
incision. Preferably, point 308 will be approximately the center of 
bearing 54 in cannula 50 (FIG. 1). A more complete description of remote 
center positioner 300 is described in commonly assigned co-pending 
application Ser. No. 08/062,404 filed May 14, 1993 REMOTE CENTER 
POSITIONER, which is incorporated herein by reference. 
A first linkage means is indicated generally by the numeral 321 and a 
second linkage in the form of a parallelogram is indicated by the numeral 
323. The first linkage means is pivotally mounted on a base plate for 
rotation about an x--x axis. The second linkage means is pivotally 
connected to the first linkage means and is adapted to move in a plane 
parallel to the first linkage. Five link members (including extensions 
thereof), 311, 312, 313, 314, and 315 are connected together with pivot 
joints 316-320. A portion of element 313 extends beyond pivot 320 of the 
parallelogram linkage. The parallelogram linkage has an operating end at 
link member 313 and a driving end at link member 312. The elongated 
element 313 may, as desired later, carry a surgical instrument or other 
device, such as support bracket 24 of manipulator assembly 2. The pivot 
joints allow relative motion of the link members only in the plane 
containing them. 
A parallelogram linkage is formed by corresponding link members 314, 315 
and link members 312 and 313. The portions of link members 314 and 315 of 
the parallelogram are of equal length as are the portions of members 312 
and 313 of the parallelogram. These members are connected together in a 
parallelogram for relative movement only in the plane formed by the 
members. A rotatable joint generally indicated by the numeral 322 is 
connected to a suitable base 324. The rotatable joint 322 is mounted on a 
base plate 326 adapted to be fixedly mounted to the base support means 
324. A pivot plate 328 is pivotally mounted to base plate 326 by suitable 
means at, such as, pivots 330, 332. Thus pivot plate 328 may be rotated 
about axis x--x through a desired angle .THETA.2. This may be accomplished 
manually or by a suitable pivot drive motor 334. 
A first linkage is pivotally mounted on the pivot plate 328 of the 
rotatable joint 322. The linkage elements 311, 312 and the link members 
are relatively stiff or inflexible so that they may adequately support an 
instrument used in surgical operations. Rods made of aluminum or other 
metal are useful as such links. The linkage elements 311 and 312 are 
pivotally mounted on base plate 328 for rotation with respect to the 
rotatable joint by pivots 336 and 338. At least one of the pivots 336, 338 
is positioned so that its axis of rotation is normal to and intersects the 
x--x axis. Movement may occur manually or may occur using a linkage drive 
motor 340. The first linkage is also shaped in the form of a parallelogram 
formed by linkage elements 311, and 312; the portion of link member 315 
connected thereto by pivots 316, 318; and base plate 328. One of the link 
members 315 is thus utilized in both the first 321 and second 323 linkage 
means. Linkage element 312 also forms a common link of both the first 
linkage means 321 and the second linkage means 323. In accordance with the 
invention, a remote center of spherical rotation 308 is provided by the 
above described embodiment of apparatus when the linkage element 311 is 
rotated and/or when pivot plate 328 is rotated about axis x--x. Thus, the 
end of element 313 can be moved through desired angles .THETA.1 and 
.THETA.2 or rotated about its own axis while the remote center of rotation 
remains at the same location. 
FIG. 9 also shows an inclinometer not shown attached to the base of remote 
center positioner 300. The remote center positioner may be mounted at an 
arbitrary orientation with respect to vertical depending on the particular 
surgery to be performed, and inclinometer not shown can be used to measure 
this orientation. The measured orientation can be used to calculate and 
implement servo control signals necessary to control the telerobotic 
system so as to prevent gravitational forces acting on the system 
mechanisms from being felt by the surgeon. 
Variations and changes may be made by others without departing from the 
spirit of the present invention. For example, it should be understood that 
the present invention is not limited to endoscopic surgery. In fact, 
instrument holder 4, along with a telerobotic control mechanism, would be 
particularly useful during open surgical procedures, allowing a surgeon to 
perform an operation from a remote location, such as a different room or a 
completely different hospital.