Abstract:
A surgical drape comprises an exterior surface adjacent to a sterile field for performing a surgical procedure and an interior surface forming a cavity for receiving a non-sterile portion of a robotic surgical system. The surgical drape also includes a first vent through the interior and exterior surfaces spaced apart from a second vent through the interior and exterior surfaces to create convection heat venting through the surgical drape. The exterior and interior surfaces include a window for positioning adjacent to a monitor screen, the window having a static charge. 
     The drape further comprises second drape section connected to a first drape section and including an instrument sterile adapter for engaging a surgical tool and another non-sterile portion of the robotic surgical system, the sterile adapter configured to transfer signals between the surgical tool and the other non-sterile portion of the robotic surgical system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of pending U.S. application Ser. No. 12/760,779, filed Apr. 15, 2010, now U.S. Pat. No. 8,202,278, which is a continuation of pending U.S. application Ser. No. 11/240,113, filed Sep. 30, 2005, now U.S. Pat. No. 7,727,244, which is a continuation-in-part of pending U.S. patent application Ser. No. 10/922,346, filed Aug. 19, 2004, now U.S. Pat. No. 7,357,774, which is a continuation of U.S. patent application Ser. No. 10/004,399, filed Oct. 30, 2001, now abandoned, which is a continuation of U.S. patent application Ser. No. 09/406,360, filed Sep. 28, 1999, now U.S. Pat. No. 6,346,072, which is a continuation of U.S. patent application Ser. No. 08/975,617, filed Nov. 21, 1997, now U.S. Pat. No. 6,132,368, the full disclosures of which are hereby incorporated by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to surgical robot systems and, more particularly, to sterile drapes for covering portions of the surgical robot system. 
     BACKGROUND 
     In robotically-assisted or telerobotic surgery, the surgeon typically operates a master controller to remotely control the motion of surgical instruments at the surgical site from a location that may be remote from the patient (e.g., across the operating room, in a different room or a completely different building from the patient). The master controller usually includes one or more hand input devices, such as joysticks, exoskeletal gloves or the like, which are coupled to the surgical instruments with servo motors for articulating the instruments at the surgical site. The servo motors are typically part of an electromechanical device or surgical manipulator (“the slave”) that supports and controls the surgical instruments that have been introduced directly into an open surgical site or through trocar sleeves into a body cavity, such as the patient&#39;s abdomen. During the operation, the surgical manipulator provides mechanical articulation and control of a variety of surgical instruments, such as tissue graspers, needle drivers, electrosurgical cautery probes, etc., that each perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, or dissecting, cauterizing or coagulating tissue. 
     This new method of performing telerobotic surgery through remote manipulation has, of course, created many new challenges. One such challenge results from the fact that a portion of the electromechanical surgical manipulator will be in direct contact with the surgical instruments, and will also be positioned adjacent the operation site. Accordingly, the surgical manipulator may become contaminated during surgery and is typically disposed of or sterilized between operations. From a cost perspective, it would be preferable to sterilize the device. However, the servo motors, sensors, encoders, and electrical connections that are necessary to robotically control the motors typically cannot be sterilized using conventional methods, e.g., steam, heat and pressure, or chemicals, because the system parts would be damaged or destroyed in the sterilization process. 
     A sterile drape has been previously used to cover the surgical manipulator but the drape may at times be difficult or time-consuming to install, limit movement of the surgical manipulator, or hinder the surgeon&#39;s view of the surgical site. Prior drapes have also at times hindered visibility or touching of the monitor screen. 
     What is needed, therefore, are telerobotic systems, apparatus, and methods for minimizing the need for sterilization to improve cost efficiency while protecting the system and the surgical patient. In addition, these systems and methods should be designed to be simple to install and to minimize installation time while allowing for maximum freedom of movement and visibility during the surgical procedure. Accordingly, a sterile drape, system, and method for robotic surgery having improved efficiency and effectiveness are highly desirable. 
     SUMMARY 
     The present invention provides an improved sterile drape, system, and method for draping of portions of a telerobotic surgical system. 
     In accordance with an embodiment of the present invention, a sterile drape to cover a non-sterile portion of a robotic surgical system is provided, the sterile drape including an exterior surface adjacent to a sterile field for performing a surgical procedure, and an interior surface forming a cavity for receiving the non-sterile portion of the robotic surgical system. The drape further includes a fastener coupled to the exterior surface for securing the sterile drape to the non-sterile portion of the robotic surgical system while reducing the volume of the sterile drape. 
     In accordance with another embodiment of the present invention, a robotic surgical system for performing a procedure within a sterile field is provided, the system including a manipulator arm, a monitor, and a sterile drape similar to that described above and including an interior surface forming cavities for receiving the manipulator arm and the monitor, and a plurality of fasteners for securing the sterile drape to the manipulator arm and the monitor. 
     In accordance with yet another embodiment of the present invention, a method of draping a robotic surgical system is provided, the method including providing a sterile drape similar to that described above and including an open end with an integral cuff, positioning the open end at a portion of the robotic surgical system, holding the integral cuff to unfold the sterile drape over the portion of the robotic surgical system, and securing the sterile drape to the portion of the robotic surgical system using the fastener. 
     Advantageously, the present invention provides for improved installation of the drape and improved visibility of the surgical site and monitor while allowing for freedom of movement of the surgical manipulator. 
     The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an operating room, illustrating a telerobotic surgical system and method in accordance with an embodiment of the present invention. 
         FIG. 2  is an enlarged view of the operating room of  FIG. 1  illustrating a pair of mounting joints coupled to an operating table according to the present invention. 
         FIG. 3A  is a perspective view of a robotic surgical manipulator that is partially covered by a sterile drape in accordance with an embodiment of the present invention. 
         FIG. 3B  is a perspective view of the robotic surgical manipulator of  FIG. 3A  without the sterile drape to illustrate a multiple degree of freedom arm coupling a driving assembly with a wrist unit and a surgical tool. 
         FIG. 4  illustrates the robotic surgical manipulator of  FIGS. 3A-3B  incorporating a camera and endoscope for viewing the surgical site. 
         FIG. 5  is a partial view of the robotic manipulator of  FIGS. 3A-3B , illustrating mechanical and electrical couplings between the arm and the wrist unit. 
         FIG. 6  is a partially cut-away sectional view of a forearm and a carriage of the manipulator of  FIGS. 3A and 3B . 
         FIG. 7  is a perspective view of the wrist unit in accordance with an embodiment of the present invention. 
         FIG. 8  is a side cross-sectional view of a portion of the robotic manipulator, illustrating the arm and the drive assembly. 
         FIGS. 9A-9E  are views of a monitor drape in accordance with an embodiment of the present invention. 
         FIGS. 10A-10J  are views of an ECM (camera arm) drape in accordance with an embodiment of the present invention. 
         FIGS. 11A-11L  are views of a PSM drape in accordance with an embodiment of the present invention. 
     
    
    
     Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures. It should also be appreciated that the figures may not be necessarily drawn to scale. 
     DETAILED DESCRIPTION 
     The present invention provides a multi-component system and method for performing robotically-assisted surgical procedures on a patient, particularly including open surgical procedures, neurosurgical procedures, such as stereotaxy, and endoscopic procedures, such as laparoscopy, arthroscopy, thoracoscopy and the like. The system and method of the present invention is particularly useful as part of a telerobotic surgical system that allows the surgeon to manipulate the surgical instruments through a servomechanism from a remote location from the patient. To that end, the manipulator apparatus or slave of the present invention will usually be driven by a kinematically-equivalent master to form a telepresence system with force reflection. A description of a suitable slave-master system can be found in U.S. patent application Ser. No. 08/517,053, filed Aug. 21, 1995, the complete disclosure of which is incorporated herein by reference for all purposes. 
     Referring to the drawings in detail, wherein like numerals indicate like elements, a telerobotic surgical system  2  is illustrated according to an embodiment of the present invention. As shown in  FIG. 1 , telerobotic system  2  generally includes one or more surgical manipulator assemblies  4  mounted to or near an operating table O, and a control assembly  6  for allowing the surgeon S to view the surgical site and to control the manipulator assemblies  4 . The system  2  will also include one or more viewing scope assemblies  19  and a plurality of surgical instrument assemblies  20  adapted for being removably coupled to manipulator assemblies  4  (discussed in detail below). Telerobotic system  2  usually includes at least two manipulator assemblies  4  and preferably three manipulator assemblies  4 . The exact number of manipulator assemblies  4  will depend on the surgical procedure and the space constraints within the operating room among other factors. As discussed in detail below, one of the assemblies  4  will typically operate a viewing scope assembly  19  (e.g., in endoscopic procedures) for viewing the surgical site, while the other manipulator assemblies  4  operate surgical instruments  20  for performing various procedures on the patient P. 
     Control assembly  6  may be located at a surgeon&#39;s console C which is usually located in the same room as operating table O so that the surgeon may speak to his/her assistant(s) A and directly monitor the operating procedure. However, it should be understood that the surgeon S can be located in a different room or a completely different building from the patient P. Control assembly  6  generally includes a support  8 , a monitor  10  for displaying an image of the surgical site to the surgeon S, and one or more controller(s)  12  for controlling manipulator assemblies  4 . Controller(s)  12  may include a variety of input devices, such as joysticks, gloves, trigger-guns, hand-operated controllers, voice recognition devices or the like. Preferably, controller(s)  12  will be provided with the same degrees of freedom as the associated surgical instrument assemblies  20  to provide the surgeon with telepresence, or the perception that the controller(s)  12  are integral with the instruments  20  so that the surgeon has a strong sense of directly controlling instruments  20 . Position, force, and tactile feedback sensors (not shown) may also be employed on instrument assemblies  20  to transmit position, force, and tactile sensations from the surgical instrument back to the surgeon&#39;s hands as he/she operates the telerobotic system. One suitable system and method for providing telepresence to the operator is described in U.S. patent application Ser. No. 08/517,053, filed Aug. 21, 1995, which has previously been incorporated herein by reference. 
     Monitor  10  will be suitably coupled to the viewing scope assembly  19  such that an image of the surgical site is provided adjacent the surgeon&#39;s hands on surgeon console C. Preferably, monitor  10  will display an inverted image on a display  18  that is oriented so that the surgeon feels that he or she is actually looking directly down onto the operating site. To that end, an image of the surgical instruments  20  appears to be located substantially where the operator&#39;s hands are located even though the observation points (i.e., the endoscope or viewing camera) may not be from the point of view of the image. In addition, the real-time image is preferably transformed into a perspective image such that the operator can manipulate the end effector and the hand control as if viewing the workspace in substantially true presence. By true presence, it is meant that the presentation of an image is a true perspective image simulating the viewpoint of an operator that is physically manipulating the surgical instruments  20 . Thus, a controller (not shown) transforms the coordinates of the surgical instruments  20  to a perceived position so that the perspective image is the image that one would see if the camera or endoscope was located directly behind the surgical instruments  20 . A suitable coordinate transformation system for providing this virtual image is described in U.S. patent application Ser. No. 08/239,086, filed May 5, 1994, now U.S. Pat. No. 5,631,973, the complete disclosure of which is incorporated herein by reference for all purposes. 
     As shown in  FIG. 1 , a servomechanism  16  is provided for transferring the mechanical motion of controllers  12  to manipulator assemblies  4 . Servomechanism  16  may be separate from, or integral with manipulator assemblies  4 . Servomechanism  16  will usually provide force and torque feedback from the surgical instruments  20  to the hand-operated controllers  12 . In addition, servomechanism  16  will include a safety monitoring controller (not shown) that may freeze or at least inhibit all robot motion in response to recognized conditions (e.g., exertion of excessive force on the patient, “running away” of the manipulator assemblies  4 , etc.). The servomechanism 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, manipulator assemblies  4  have a relatively low inertia and the drive motors  170  (see  FIG. 8 ) have relatively low ratio gear or pulley couplings. Any suitable conventional or specialized servomechanism may be used in the practice of the present invention, with those incorporating force and torque feedback being particularly preferred for telepresence operation of the system. 
     Referring to  FIG. 7 , surgical instrument assemblies  20  each include a wrist unit  22  and a surgical tool  24  ( FIGS. 3A and 3B ) removably attached to wrist unit  22 . As discussed in detail below, each wrist unit  22  generally includes an elongate shaft  56  having a proximal cap  58  and a distal wrist  60  pivotally coupled to surgical tool  24 . Each wrist unit  22  is substantially the same, and will have different or the same surgical tools  24  attached thereto, depending on the requirements of the surgical procedure. Alternatively, wrist units  22  may have specialized wrists  60  designed for individual surgical tools  24  so that the wrist units  22  may be used with conventional tools  24 . As shown in  FIG. 1 , the instrument assemblies  20  are usually assembled onto a table T or other suitable support adjacent the operating table O. According to a method of the present invention (described below), wrist units  22  and their associated surgical tools  24  can be quickly exchanged during the surgical procedure by coupling and decoupling wrist unit shafts  56  from manipulator assemblies  4 . 
     Referring to  FIG. 2 , each manipulator assembly  4  is preferably mounted to operating table O by a mounting joint  30 . Mounting joints  30  provide a number of degrees of freedom (preferably at least 5) to assemblies  4 , and they include a brake (not shown) so that assemblies  4  can be fixed at a suitable position and orientation relative to the patient. Joints  30  are mounted to a receptacle  32  for mounting joints  30  to operating table O, and for connecting each manipulator assembly  4  to servomechanism  16 . In addition, receptacle  32  may connect joints  30  to other systems, such as an RF electrical power source, a suction-irrigation system, etc. Receptacle  32  includes a mounting arm  34  that is slidably disposed along an outer rail  36  of operating table O. Manipulator assemblies  4  may also be positioned over the operating table O with other mechanisms. For example, the system may incorporate a support system (coupled to the ceiling or a wall of the operating room) that moves and holds one or more manipulator assemblies  4  over the patient. 
     Referring now to  FIGS. 3-8 , manipulator assembly  4  will be described in further detail. Manipulator assembly  4  is a three-component apparatus that includes a non-sterile drive and control component, a sterilizable end effector or surgical tool (i.e., surgical instrument assembly  20 ), and an intermediate connector component. The intermediate connector includes mechanical elements for coupling the surgical tool  24  with the drive and control component, and for transferring motion from the drive component to the surgical tool  24 . As shown in  FIG. 3B , the drive and control component generally includes a drive assembly  40  and a multiple degree of freedom robotic arm  42  coupled to a mounting bracket  44 , which is adapted for mounting onto mounting joints  30  ( FIG. 2 ). Preferably, drive assembly  40  and robotic arm  42  are pivotally coupled to bracket  44  about an X-axis, which extends through a remote center of spherical rotation  45  (see  FIG. 8 , discussed in further detail below). Manipulator assembly  4  further includes a forearm assembly  46  fixed to a distal end  48  of arm  42 , and a wrist unit adaptor  52  coupled to forearm assembly  46  for mounting wrist unit  22  and surgical tool  24  to manipulator assembly  4 . 
     For endoscopic procedures, manipulator assembly  4  additionally includes a cannula adaptor  64  attached to a lower portion of forearm  46  for mounting a cannula  66  to manipulator assembly  4 . Alternatively, cannula  66  may be an integral cannula (not shown) that is built into forearm assembly  46  (i.e., non-removable). Cannula  66  may include a force sensing element (not shown), such as a strain gauge or force-sensing resistor, mounted to an annular bearing within cannula  66 . The force sensing bearing supports surgical tool  24  during surgery, allowing the tool to rotate and move axially through the central bore of the bearing. In addition, the bearing transmits lateral forces exerted by the surgical tool  24  to the force sensing element, which is connected to servomechanism  16  for transmitting these forces to controller(s)  12 . In this manner, forces acting on surgical tools  24  can be detected without disturbances from forces acting on cannula  66 , such as the tissue surrounding the surgical incision, or by gravity and inertial forces acting on manipulator assembly  4 . This facilitates the use of manipulator assembly  4  in a robotic system because the surgeon will directly sense the forces acting against the surgical tool  24 . 
     As shown in  FIG. 3A , manipulator assembly  4  further includes a sterile drape  70  sized to cover substantially the entire manipulator assembly  4 . Drape  70  has a pair of holes  72 ,  74  sized and arranged so that wrist unit adaptor  52  and cannula adaptor  64  may extend through holes  72 ,  74  to mount wrist unit  22  and cannula  66  to manipulator assembly  4 . Sterile drape  70  comprises a material configured to effectively shield manipulator assembly  4  from the surgical site so that most of the components of assembly  4  (i.e., arm  42 , drive assembly  40  and forearm assembly  46 ) do not have to be sterilized prior to, or following the surgical procedure. 
     As shown in  FIG. 3A , wrist unit adaptor  52  and cannula adaptor  64  extend through holes  72 ,  74  of drape  70  so that forearm assembly  46  and the remainder of manipulator assembly  4  remain shielded from the patient during the procedure. In one embodiment, wrist unit adaptor  52  and cannula adaptor  64  are manufactured as reusable components that will be sterilized because these components extend into the sterile field of the surgical site. Wrist unit and cannula adapters  52 ,  64  may be sterilized by normal methods, i.e., steam, heat and pressure, chemicals and the like. Referring again to  FIG. 3B , wrist unit adaptor  52  includes an opening  80  for receiving shaft  56  of wrist unit  22 . As discussed in detail below, shaft  56  can be laterally urged through opening  80  and snap-fit into adaptor  52  such that the non-exposed portion of wrist unit adaptor  52  remains sterile (i.e., remains on the sterile side of drape  70  opposite the sterile field). Wrist unit adaptor  52  may also include a latch (not shown) for securing wrist unit  22  therein. Similarly, cannula adaptor  64  includes an opening  82  for snap fitting cannula  66  thereto such that the non-exposed portion of adaptor  64  remains sterile during the surgical procedure. 
     As shown in  FIG. 4 , wrist unit adaptor  52  may also be configured to receive a viewing scope  100  for viewing the surgical site. For endoscopic procedures, viewing scope  100  can be a conventional endoscope, which typically includes a rigid, elongated tube  102  containing a lens system (not shown) and a camera mount  104  at the proximal end of the tube  102 . A small video camera  106  is preferably attached to the camera mount  104  and connected to video monitor  10  to provide a video image of the procedure. Preferably, the scope  100  has a distal end (not shown) configured to allow lateral or angled viewing relative to tube  102 . The viewing scope may also have a guidable tip that can be deflected or rotated by manipulating an actuator on a proximal end of tube  102 . This type of scope is commercially available from Baxter Healthcare Corp. of Deerfield, Ill., or Origin Medsystems, Inc. of Menlo Park, Calif. 
     As shown in  FIG. 4 , viewing scope  100  further includes a scope adaptor  110  for coupling viewing scope  100  to wrist unit adaptor  52 . Scope adaptor  110  is sterilizable, ETO and autoclavable, and it includes a plurality of motion feed-throughs (not shown) for transferring motion from drive assembly  40  to scope  100 . In the preferred configuration, the motion includes pitch and yaw motion, rotation about the Z-axis, and movement along the Z-axis. 
     Referring now to  FIGS. 5 and 6 , forearm assembly  46  will be described in further detail. As shown in  FIG. 5 , forearm assembly  46  includes a housing  120  fixed to arm  42  and a movable carriage  122  slidably coupled to housing  120 . Carriage  122  slidably mounts wrist unit adaptor  52  to housing  120  for moving wrist unit adaptor  52  and wrist unit  20  in the Z-direction. In addition, carriage  122  defines a number of openings  123  for transferring motion and electrical signals from forearm assembly  46  to wrist unit adaptor  52 . As shown in  FIG. 6 , a plurality of rotatable shafts  124  are mounted within housing  120  for transferring motion from arm  42  through openings  123  to wrist unit adaptor  52  and wrist unit  22 . Rotating shafts  124  preferably provide at least four degrees of freedom to wrist unit  22 , including yaw and pitch motion of surgical tool  24  about wrist  60  of wrist unit  22 , rotation of wrist unit  22  about the Z-axis and actuation of tool  24 . The system may also be configured to provide more or less degrees of freedom, if desired. Actuation of tool  24  may include a variety of motions, such as opening and closing jaws, graspers or scissors, applying clips or staples and the like. Motion of wrist unit  22  and tool  24  in the Z direction is provided by a pair of carriage cable drives  126  extending between rotatable pulleys  128 ,  129  on either end of forearm housing  120 . Cable drives  126  function to move carriage  122  and wrist unit  22  in the Z direction relative to forearm housing  120 . 
     As shown in  FIG. 6 , distal end  48  of arm  42  includes a coupling assembly  130  having a plurality of motion feed-throughs  132  for transferring motion from arm  42  to forearm assembly  46 . In addition, coupling assembly  130  includes a number of electrical connectors (not shown) for transferring electrical signals from arm  42  to wrist unit  22 . Similarly, wrist unit adaptor  52  includes a plurality of motion feed-throughs (not shown) and electrical connections (not shown) for transferring motion, and for sending and receiving electrical signals to and from wrist unit  22  (e.g., for sending and receiving force and torque feedback signals from the surgical site to controllers  12 ). The components on either side of coupling assembly  130  and wrist unit adaptor  52  have a finite range of motion. Usually, this range of motion will be at least 1 revolution and preferably greater than 1 revolution. These ranges of motion are aligned with each other when the forearm assembly  46  is mechanically coupled to the coupling assembly  130  and when wrist unit adaptor  52  is mechanically coupled to the forearm  46 . 
     Referring to  FIG. 7 , wrist unit  22  will now be described in further detail. As shown, wrist unit  22  includes a hollow shaft  56  having a cap  58  attached to its proximal end and a wrist  60  attached to its distal end. Wrist  60  includes a coupling (not shown) for removably coupling a variety of surgical tools  24  to shaft  56 . Shaft  56  is rotatably coupled to cap  58  for providing rotation of shaft  56  and tool  24  about the longitudinal axis of shaft  56  (i.e., the Z axis). Cap  58  houses a mechanism (not shown) for transferring motion from wrist unit adaptor  52  to drive cables (not shown) within shaft  56 . The drive cables are suitably coupled to drive pulleys within shaft  56  to pivot tool  24  about wrist  60 , and to actuate end effectors  140  on tool  24 . Wrist  60  may also be operated by other mechanisms, such as differential gears, push-rods, or the like. 
     Tool  24  is removably coupled to wrist  60  of wrist unit  22 . Tool  24  will preferably include an end effector  65  ( FIGS. 3A and 3B ) having a tactile sensor array (not shown) for providing tactile feedback to the surgeon. Tool  24  may include a variety of articulated tools, such as jaws, scissors, graspers, needle holders, micro dissectors, staple appliers, tackers, suction irrigation tools, clip appliers, that have end effectors driven by wire links, eccentric cams, push-rods or other mechanisms. In addition, tool  24  may comprise a non-articulated instrument, such as cutting blades, probes, irrigators, catheters or suction orifices. Alternatively, tool  24  may comprise an electrosurgical probe for ablating, resecting, cutting or coagulating tissue. In the latter embodiment, wrist unit  22  will include a conductive element, such as a proximal banana plug coupled to a lead wire or rod extending through shaft  56  to tool  24 . 
     Referring to  FIGS. 4 and 8 , a specific configuration of the drive and control component of the present invention (i.e., the robotic arm  42  and drive assembly  40 ) will be described in further detail. As discussed above, arm  42  and drive assembly  40  are rotatably coupled about a pair of pins  150  extending from mounting bracket  44 . Arm  42  preferably comprises an elongate, substantially rigid body  152  with a distal end  48  coupled to forearm assembly  48  and a proximal end  154  pivotally coupled to drive assembly  40  and bracket  44  for rotation about pitch and yaw or the X and Y axes (note that the Y axis is perpendicular to the page and extends through point  45 , see  FIG. 8 ). Arm  40  may have other configurations, such as an elbow arm (similar to the human arm), prismatic arm (straight extendable) or the like. A stationary yaw motor  156  is mounted to mounting bracket  44  for rotating arm  42  and drive assembly  40  about the X-axis. Drive assembly  40  also includes a pitch motor  158  coupled to arm  42  for rotating arm about the Y axis. A pair of substantially rigid linkage elements  160 ,  124  extend from bracket  44  to robotic arm  42  to pivotally couple arm  42  to bracket  44  about Y-axis. One of the linkage elements  160  is pivotally coupled to arm  42 , and the other linkage element  124  is pivotally coupled to a third linkage element  164  extending parallel to arm  42 . Preferably, robotic arm  42  is a channel shaped rigid element that at least partially houses the third linkage element  164 . The linkage elements  160 ,  124  and  164  and arm  42  form a parallelogram linkage in which the members are connected together in a parallelogram for relative movement only in the plane formed by the members. 
     The Z-axis of wrist unit  22  held at the distal end  48  of arm  42  intersects the x axis of the parallelogram linkage described above. Wrist unit  22  has a remote center of spherical rotation about the position indicated by the numeral  45  in  FIG. 8 . Thus, the distal end of wrist unit  22  can be rotated about its own axis or the X and Y axes while the remote center of rotation  45  remains at the same location. A more complete description of a remote center positioning device can be found in U.S. patent application Ser. No. 08/504,301, filed Jul. 20, 1995, now U.S. Pat. No. 5,931,832, the complete disclosure of which is incorporated herein by reference for all purposes. It should be noted that arm  42  and drive assembly  40  may be used with a broad range of positioning devices other than that described above and shown in  FIG. 8 , such as a stereotaxic positioner, a fixed gimbal, or the like. 
     Referring again to  FIG. 8 , drive assembly  40  further includes a plurality of drive motors  170  coupled to arm  42  for rotation therewith. Pitch and yaw motors  156 ,  158  control the motion of arm  42  (and drive motors  170 ) about the X and Y axes and drive motors  170  control the motion of wrist unit  22  and surgical tool  24 . Preferably, at least five drive motors  170  are coupled to arm  42  for providing at least five degrees of freedom to wrist unit  22 . Drive motors  170  will preferably include encoders (not shown) for responding to servomechanism  16  and force sensors (not shown) for transmitting force and torque feedback to the surgeon S. As discussed above, the five degrees of freedom preferably include movement of carriage  122  and wrist unit  22  in the Z-direction, rotation of wrist unit  22  about the Z-axis, pitch and yaw rotation of surgical tool  24  around wrist  60  and actuation of tool  24 . 
     As shown, cables  172  extend from each motor  170  around a motor drive pulley  174 , an idler pulley  176  within arm  42  and along a relatively large pot capstan  178  to minimize the effect of friction torque on cables  172 . The cables  172  each extend around another idler pulley  180  at distal end  48  of arm  42 , around a coupling drive pulley  182  and back to the motor  170 . The cables  172  will preferably be tensioned at the motor drive pulley  174  and anchored there as well as at the coupling drive pulley  182 . As shown in  FIG. 8 , coupling drive pulley  182  is connected to a plurality of smaller pulleys  184  within coupling assembly  130  via a plurality of cables  186  for transferring motion from the motors  170  to wrist unit adaptor  52 . 
     A method for performing a surgical procedure on a patient according to the present invention will now be described with reference to  FIGS. 1-8 . As shown in  FIG. 2 , mounting joints  30  are attached to receptacle  32 , which is attached to the operating table O by sliding mounting arm  34  along rail  36 . Each manipulator assembly  4  is then attached to its respective mounting joint  30  and articulated into the proper position and orientation relative to the patient P. Receptacles  32  are then coupled to servomechanism  16  and other systems that may be required during the surgical procedure, such as an RF power supply, a suction/irrigation system, etc. Sterile drapes  70  are placed over the manipulator assemblies  4  before, during, or after the patient has been anesthetized ( FIG. 3A ). To prepare for the surgical procedure, manipulator assemblies  4  may or may not be chemically cleaned prior to covering them with drapes  70 . Wrist unit adapters  52 , cannula adapters  64 , and scope adapters  110  are snapped onto forearm assemblies  46  of manipulator assemblies  4  (see  FIGS. 3B and 5 ). The number and relative positions of scope adapters  110  and wrist unit adapters  52  will, of course, depend on the individual surgical procedure (e.g., cannula adapters  64  may not be required for open surgical procedures). 
     During the surgical procedure, surgical instrument assemblies  20  are coupled to their respective manipulator assemblies  4  by laterally urging each respective wrist unit shaft  56  through opening  80  of wrist unit adaptor  52 . Each wrist unit  22  will have suitable identification means (not shown) to quickly and easily indicate what type of tool  24  is connected to the wrist unit  22 . When the surgeon wishes to change surgical tools  24 , he or she manipulates controller(s)  12  so that carriage  122  moves to a top or proximal position of travel along forearm assembly  46  (see  FIG. 3B ). In this position, surgical tool  24  is within cannula  66  or during open procedures, removed from the surgical site. The assistant(s) A then pulls upward on wrist cap  58  to release the latch (not shown), thereby allowing wrist unit  22  to slide further upwards and out of cannula  66 . The assistant(s) A may then pull wrist unit  22  laterally to decouple it from wrist unit adaptor  52 . When wrist unit  22  is no longer coupled to adaptor  52 , the control mechanism understands that the system is in “tool change mode”, and drives carriage  122  to the proximal position if it has not already been moved there by the surgeon. 
     To couple another surgical instrument assembly  20  to manipulator assembly  4 , the assistant(s) A grabs another assembly  20  from table T, laterally urges wrist unit shaft  56  into opening  80  of wrist unit adaptor  52 , and then moves wrist unit  22  downward so that surgical tool  24  resides within cannula  66  (see  FIGS. 1 and 3B ). This downward movement of wrist unit  22  automatically mates the electrical couplings and motion feed-throughs (not shown) within wrist cap  58  and wrist unit adaptor  52 . The system may include a control mechanism configured to lock carriage  122  travel at the top or proximal position, e.g., by actuating a brake (not shown), until the couplings are mated and wrist unit  22  is no longer being moved downward. At this point, the surgeon S may continue the surgical procedure. 
     The system and method of the present invention preferably includes a mechanism for counting the number of times wrist unit  22  is decoupled and coupled from wrist unit adaptor  52 . In this manner, the manufacturer may limit the number of times wrist unit  22  can be used. In a specific configuration, an integrated circuit chip (not shown) is housed within wrist cap  58 . The circuit chip counts the number of times wrist unit  22  is coupled to wrist unit adaptor  52 , e.g., 20 times, and a warning shows up on the surgeon&#39;s console C. The control system then downgrades the performance of the system by reducing the load it can deliver or increasing apparent backlash. 
     Referring now to  FIGS. 9A-9E , a monitor drape package  200  including a monitor drape  204  that is part of sterile drape  70  (described above with reference to  FIG. 3A ) is shown. Monitor drape  204  may be a connected or disconnected section of sterile drape  70 .  FIG. 9A  shows monitor drape package  200  including a monitor drape pouch  202  with monitor drape  204  folded inside. Monitor drape  204  is a disposable sterile drape assembly which is placed over a monitor and monitor mount to maintain a sterile barrier between the monitor/monitor mount and the sterile field of the surgical procedure. Advantageously, various features of the monitor drape aid the draping and installation process. 
       FIG. 9B  shows monitor drape  204  removed from pouch  202  with drape  204  including a touch screen window  206  to be placed adjacent to the screen of a monitor (e.g., monitor  10  of  FIG. 1 ). Touch screen window  206  is between two flaps  208  of monitor drape  204  and is not folded to reduce creases and increase adhesion to the monitor screen. In one example, touch screen window  206  is a clear, static-cling window to be positioned in front of the monitor screen. The clear window allows the user to see and use a touch screen monitor while maintaining a sterile barrier. Window  206  has a static charge which maintains a static cling function allowing window  206  to sit flat against the monitor screen to reduce reflections and glare and to keep the window secure for touch screen usage. 
       FIG. 9C  shows monitor drape  204  with flaps  208  unfolded. As previously noted, monitor drape  204  is folded in a way to assure that the screen window section is not folded, thereby reducing creases in the material and allowing flatter positioning on the monitor screen. 
       FIG. 9D  shows four loop fasteners  212 , two vents  214 , a strap  216 , a permanent cuff  220 , a blue tape  218  on the edge of cuff  220 , and a purse string  222  built into cuff  220 . Loop fasteners  212  are included on either side of screen window  206  on the inside of the drape. Loop fasteners  212  include strips of Velcro which mate with hook fasteners (not shown) located on the back of the monitor mount. These hook and loop fasteners allow the user to quickly pull the drape taught and fixed in position in front of the monitor screen. Vents  214  allow heat generated by the monitor to vent from monitor drape  204 . The vents are above and below the monitor area to allow for convection heat venting. Vents  214  also allow for the transmission of sound from the sterile field to a microphone installed proximate the monitor. Straps  216  help control drape  204  and reduce the visual size of the drape (i.e., reduce the volume of or space taken up by the unfolded drape). Blue tape  218  acts as a physical marker on the drape to designate the sterile and non-sterile ends. By having blue tape  218  act as a marker, a non-sterile person can know to pull on the non-sterile side if assisting the sterile scrub nurse. Purse string  222  allows the user to pull monitor drape  204  tight around the monitor mount at the end of the drape. 
       FIG. 9E  shows an enlarged view of the drape area proximate cuff  220 , including a tear strip  224 . Cuff  220  is integral to the end of the drape. A sterile scrub nurse may place his or her hands into these cuffs when pulling the drape over the monitor. By having a cuff, the user is assured that their hands are not touching something that is non-sterile as they work their way along the monitor. Tear strips  224  are used to control unfolding of the drape during installation. Tear strips  224  hold the drape in its folded position (as shown for example in  FIG. 9C ), and as the user installs the drape, tear strips  224  are broken as the drape is pulled back over the monitor. 
     Referring now to  FIGS. 10A-10J , an endoscope camera manipulator (ECM) (camera arm) drape package  300  including an ECM drape  304  that is part of sterile drape  70  (described above with reference to  FIG. 3A ) is shown. ECM drape  304  may be a connected or disconnected section of sterile drape  70 .  FIG. 10A  shows ECM drape package  300  including an ECM drape pouch  302  with ECM drape  304  folded inside. The ECM drape is a disposable sterile drape assembly designed to establish a sterile barrier between the non-sterile ECM camera arm and the sterile field of the surgical procedure. Advantageously, various features of ECM drape  304  aid the draping and installation process. 
       FIG. 10B  shows ECM drape  304  removed from pouch  302 . ECM drape  304  is folded with two flaps  308  and arrow labels show the direction for unfolding of flaps  308 .  FIG. 10C  shows ECM drape  304  with flaps  308  unfolded.  FIG. 10D  shows visual indicators  310  for positioning or locating ECM drape  304  on the ECM arm. Visual indicators  310  include a patch  312  and a patch  314  as described in more detail below with respect to  FIG. 10F .  FIG. 10E  shows a closed end of ECM drape  304  partially unfolded.  FIG. 10F  shows a reinforcement patch  312  used to keep ECM drape  304  from interfering when installing a camera on the ECM arm. Also shown is a peel-and-stick patch  314  for attaching a camera sterile adaptor. 
       FIG. 10G  shows tear strips  316  that define the main entrance/exit of the drape through which the ECM arm enters or exits ECM drape  304 . ECM drape  304  is packaged such that the folded drape can be first placed over the ECM arm. The drape is set in this initial position by using tear strips  316  which allow for the controlled unfolding of the drape by tearing when pulled on with the necessary force. The user pulls ECM drape  304  along the length of the ECM arm by placing their hands in cuffs  323  ( FIG. 10I ) and pulling the drape along the ECM arm.  FIG. 10H  shows ECM drape  304  fully unfolded. 
       FIG. 10I  shows a strap  318  at the end of ECM drape  304 , a blue tape  320  at the edge of a cuff  323 , a slit  322  in cuff  323  for wrapping the ECM drape around the monitor mount, and peel-and-stick patches  314 . ECM drape  304  includes an integral cuff  323  at the end of the drape. The sterile scrub nurse may place his or her hands into these cuffs when pulling the drape along the ECM arm, thereby assuring the user that their hands are not touching something that is non-sterile as they work their way along the ECM arm. Blue tape  320  acts as a physical marker on the drape to designate the sterile and non-sterile ends. By having blue tape  320  act as a marker, a non-sterile person can know to pull on the non-sterile side if assisting the sterile scrub nurse. 
       FIG. 10J  shows straps  318  which help to control the ECM drape and reduce the visual size of the drape (i.e., reduce the volume of or space taken up by the unfolded drape). There is one strap proximate the cannula mount area, another strap proximate a “link 3” of the ECM arm, and another strap proximate the “setup arm” (e.g., arm  42  of  FIGS. 4 and 5 ) onto which the ECM arm is mounted. 
     Referring now to  FIGS. 11A-11M , a patient side manipulator (PSM) drape package  400  including a PSM drape  404  that is part of sterile drape  70  (described above with reference to  FIG. 3A ) is shown. PSM drape  404  may be a connected or disconnected section of sterile drape  70 .  FIG. 11A  shows PSM drape package  400  including a PSM drape pouch  402  with PSM drape  404  folded inside. The PSM drape is designed to establish a sterile barrier between the non-sterile PSM arms and the sterile field of the surgical procedure. PSM drape  404  includes an integral instrument sterile adaptor (ISA) permanently mounted on the drape, with the complete assembly including the ISA, which is used to engage a surgical tool. Embodiments of applicable adaptors, tools, or accessories are described for example in U.S. Pat. Nos. 6,331,181, 6,491,701, and 6,770,081, the full disclosures of which (including disclosures incorporated by reference therein) are incorporated by reference herein for all purposes. Thus, the drape is completely disposable in one embodiment. Advantageously, various features of the PSM drape aid the draping and installation process. 
       FIG. 11B  shows PSM drape  404  removed from pouch  402 .  FIG. 11C  shows an example of a sterile adaptor  406  permanently mounted to PSM drape  404  proximate a closed end of PSM drape  404 .  FIG. 11D  shows tear strips  408  that define the main hole in the folded PSM drape and folded flaps  410 .  FIG. 11E  shows flaps  410  unfolded, and  FIG. 11F  shows PSM drape  404  completely unfolded. PSM drape  404  is packaged so that the folded drape can be first placed over the PSM arm and then the permanently mounted sterile adaptor  406  is attached to the PSM arm by first locating a front tongue feature into a bracket on the PSM arm followed by swinging the other end of the sterile adaptor until it engages a latch on the PSM arm. PSM drape  404  is maintained in this initial position by using tear strips  408  which allow for the controlled unfolding of the drape by tearing when pulled on with the necessary force. The user pulls the drape along the length of the PSM arm by placing their hands in integral cuffs  412  ( FIG. 11G ) and pulling the drape along the PSM arm. 
     FIGS.  11 G 1  and  11 G 2  show an integral cuff  412  at the open end of PSM drape  404 , the edge of cuff  412  including a blue tape  411 . The sterile scrub nurse may place his or her hands into the cuff when pulling the PSM drape along the PSM arm, and by using the cuff, the user is assured that their hands are not touching something that is non-sterile as they work their way along the PSM arm. Blue tape  411  acts as a physical marker on the drape to designate the sterile and non-sterile ends. By having this marker, a non-sterile person can know to pull on the non-sterile side when assisting the sterile scrub nurse. 
       FIG. 11H  shows straps  414  on the drape to help control the drape and reduce the visual size of the drape (i.e., reduce the volume of or space taken up by the unfolded drape). One strap is proximate the cannula mount area, another strap is proximate a “link 3” of the PSM arm, and another strap is along a “setup arm” (e.g., arm  42  of  FIGS. 4 and 5 ) onto which the PSM arm is mounted. 
       FIG. 11I  shows strips  416  along the insertion axis and a cannula mount pouch  418 . A cannula mount pouch that may be used is disclosed in co-pending U.S. patent application Ser. No. 11/240,087, filed Sep. 30, 2005, the contents of which have been previously incorporated by reference herein. Strips  416  are malleable strips on the drape in an insertion axis area. Strips  416  are attached to the drape between the sterile adaptor and the cannula mount area. Once the drape is installed on the PSM arm, the user can deform the malleable strips  416  to help fold back excess drape material. By being able to fold back and secure excess drape material, the drape can be made to closely fit the shape of the PSM arm. Advantageously, this reduces the visual size of the system and thereby allows more visibility of the patient and their surroundings to the surgeon or other user(s). Strips  416  are also sufficiently malleable to be able to open up to allow the system to achieve maximum range of motion without tearing the drape. 
       FIG. 11J  shows PSM drape  404  over a portion of PSM arm  417  and a sterile adaptor  406  in place prior to strips  416  being bent back by the user.  FIG. 11K  shows strips  416  after being bent back by the user such that PSM drape  404  more closely fits the shape of the PSM arm, thereby reducing the size of the system.  FIG. 11L  shows another view of the strips  416  which are pliable enough to be opened for maximum range of motion and which can be reshaped by the user as desired during the procedure. 
     Drapes  200 ,  300 , and  400  described above are preferably comprised of material of sufficient rigidity and strength to allow proper placement over a monitor and monitor mount, an ECM arm, and a PSM arm, respectively, and to resist tearing even under application of cyclical loads in various directions, but are preferably comprised of material of sufficient flexibility to allow movement with the active sections of the manipulator arms. Drapes  200 ,  300 , and  400  may be comprised of various durable materials, and in one example is comprised of polyethylene, polyurethane, polycarbonate, or mixtures thereof. In one embodiment, drapes  200 ,  300 , and  400  can be vacuum formed as part of a single drape or as separate drapes that can be attached to the main sterile drape  70  via adhesive, heat, RF welding, or other means. In another embodiment, drapes  200 ,  300 , and  400  may be used as disconnected drapes (but possibly adjacent to one another or with overlap) to cover different portions of the surgical robot system. 
     Advantageously, the drapes of the present invention increase visualization of the patient by reducing the size of the drapes with more form fitting features, allow for quick and simple installation, and improve the instrument sterile adaptor feature. The drapes of the present invention also maintain the sterility of a monitor screen, in particular a touch screen monitor, allow for sound to be transmitted to a microphone on the monitor drape while maintaining sterility, and reduce glare and wrinkles of the drape in front of the monitor screen. 
     Embodiments described above illustrate but do not limit the invention. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present invention. For example, although drapes for particular parts of the robotic surgical system are described in the embodiments above, other shapes and cavities for receiving other surgical system parts are within the scope of the present invention. Accordingly, the scope of the invention is defined only by the following claims.