Abstract:
The invention relates generally to robotically controlled systems, such as medical robotic systems. In one variation, a robotic catheter system is configured with a sterile barrier capable for transmitting a rotary force from a drive system on one side of the barrier to surgical tool on the other side of the sterile barrier for performing minimally invasive diagnostic and therapeutic procedures. Modularized drive systems for robotics are also disclosed herein.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    N/A 
       FIELD OF THE INVENTION 
       [0002]    The invention relates generally to robotically controlled systems, such as medical robotic systems, and more particularly to a robotic system for performing minimally invasive diagnostic and therapeutic procedures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Robotic interventional systems and devices arc well suited for use in performing various surgical, diagnostic or other medical procedures, as opposed to conventional techniques requiring a physician&#39;s to directly engage surgeon&#39;s hands access to internal organs. The benefits of robotic . interventional systems are well known. 
         [0004]      FIG. 1A  illustrates an example of a robotic catheter manipulator (“RCM”)  16  coupled to a medical tool  50 . Typically, the medical tool  50  consists of a medical device  52  and one or more drive mechanisms  54  and  56 . The drive mechanisms  54  and  56  allow a user controlling the RCM  16  to manipulate the medical device  52 . Details on various drive systems arc discussed below as well as in the commonly assigned patents and application referenced herein. In any case, the drive system or systems  54  (and/or  56 ) allow axial movement of the medical tool  50  along the RCM  16  as well as articulation of the medical device  52 . 
         [0005]      FIG. 1B  illustrates the inner mechanisms of a conventional RCM  16 . As shown, the motors  30  of the RCM  116  are affixed to the RCM  16  and convey rotation via a driver system  32  (including gears, belts, pulleys, and cables, and various other driver means to drive interface sockets  34  on the RCM  16 . The interface socket  34  receives a portion of the drive mechanism of the tool engaged allowing motion to be transferred from the motors  32  ultimately to the medical tool  50 . However, this configuration presents various challenges. In one example, rotation of the mechanism  54  about an axis of the RCM  16  requires a rotation of the motors  30  as well as the entire RCM  16 . In addition, replacing a failed motor  30  requires significant servicing of the RCM  16  due to the complex interrelation of the various gears, belts, pulleys, and cables. 
         [0006]    In addition, due to the complexity of the robotic system, it is difficult or impractical to attempt to sterilize the entire robotic assembly. Instead, the medical team establishes a sterile field over or adjacent to the robotic system. In one example, the sterile filed comprises the area above the drape, while the robotic side of the drape comprises a non-sterile environment. During such robotic procedures, it is common for the surgical team to place a sterile drape over the robotic assembly and then attach one or more sterilized tools onto the robotic assembly over through the drape. 
         [0007]    The surgical tool must break the sterile barrier when it engages the non-sterile robotic assembly. This affects the ability of the surgical team to exchange surgical tools during a procedure. If the team wants to replace the surgical tool with a second tool, because of the tool&#39;s contacts with the non-sterile robotic assembly, the surgical tool is no longer sterile and cannot be re-installed. Clearly, this shortcoming hinders the surgical team when the use and reuse of surgical tools would be beneficial to an improved procedure. 
         [0008]    One conventional method of overcoming this problem the addition of a sterile adaptor that is placed over the surgical drape. The sterile adaptor allows coupling of a surgical tool with the robotic assembly without breaking the sterile barrier. Currently used sterile adapters however have been complex assemblies that are costly and cumbersome. 
         [0009]    There remains a need to provide a robotic assembly (or components for use in the robotic assembly) that allow for removal and replacement of surgical tools without breaking the sterile barrier while reducing the complexity of any sterile adaptor. There is also a need for a robotic system that offers simplified and modularized exchange of surgical tools while maintaining or even increasing the functionality of the robotic system by, for example, maintaining precision control of the surgical tool, preserving portability of the tool so that surgical team can replace various tools during a procedure, as well as increasing the ability of the tool to interact with the patient. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Methods and devices described herein provide for improved coupling of medical tools to various medical systems. Such systems include robotic medical systems, medical driving tools, and other positioning systems. 
         [0011]    System according to the present disclosure include modular drive systems (optionally for use with a robotic surgical system) comprising, at least one rotary drive mechanism, where a portion of the rotary drive mechanism comprises a wave generating cam (the cam may be a traditional cam or may include one or more moveable surfaces, or other features to assist in transfer of motion from the motor to the drive mechanism). The rotary drive mechanism can be coupled to a base that is removably coupleable to a robotic surgical system. The system can also include a sterilized medical tool comprising at least one gear drive (also known as a “splayer”) used to actuate the tool. The gear drive typically engages at least one flexible spline gear (having a cup shape), where an interior of the cup shape removably engages the wave generating cam such that the wave generating cam deforms a portion of the cup. Continued rotation of the wave generating mechanism moves the deformed portion along the gear drive. 
         [0012]    The rotary drive mechanism of the modular drive system can include a motor (or drive train output shaft) coupled to each wave generating cam. The wave generating cam can have any number of shapes consistent with a harmonic drive type of system. For example, the wave generating cam can include an elliptical shape. In additional variations, the wave generating cam comprises at least a first and a second rolling surface on each end, where each spherical surface engages the interior of the cup. Alternatively, the wave generator cam can include a ball/roller bearing or similar structure at a perimeter with a flexible outer face that remains stationary with respect t to the flexible spline. 
         [0013]    In addition, the drive mechanisms of the modular drive arc adaptable to be moveable relative to an axis (axially moveable and/or rotatable) running along a length of the robotic surgical system. 
         [0014]    The spline gear can include a plurality of spline teeth that engage a plurality of gear teath of the gear drive. To effect driving of the system, the number of spline teeth is not equal to a number of gear teeth. The drape portion may comprise a different flexibility than the flexible spline cup. In most variations, the drape portion prevents direct contact between the sterilized medical tool and the remote control module to preserve sterility of the medical tool. 
         [0015]    In another variation, the system and devices according to the present disclosure include a robotic manipulator comprising a drive system for comprising at least one wave generating cam coupled to a motor, where the drive assembly is affixed to a base; and a robotic control manipulator having at least one modular bay for removably docking the drive system, where the entire drive system is moveable relative to the robotic control manipulator. 
         [0016]    One variation of the robotic manipulator can include a plurality of modular bays and furthering comprises a second drive system removably docked therein, where the second drive system is moveable relative to the robotic control manipulator. In an additional variation, robotic manipulator further includes a flexible spline cover located on the wave generating cam, a sterilized medical tool comprising at least one gear drive, the gear drive removeably located on the flexible spline cover, such that rotation of the wave generating cam causes a portion of the flexible spine cover to mesh with the gear drive to rotate the gear drive and actuate the medical tool. 
         [0017]    In another variation, devices under the present disclosure include a surgical barrier for use with a medical positioning system having a medical tool, where the medical positioning system includes at least a rotary driver mechanism to affect a position of the medical tool and the medical tool includes a drive mechanism, the surgical barrier comprising: a sterilizable drape portion having a surgical side and a working side, where the working side is adapted to contact a portion of the medical positioning system preserving a sterile surgical field on the surgical side; at least one flexible cup in the drape portion and having a shape such that the working side of the cup receives a driver portion of the rotary driver mechanism and the surgical side of the cup nests within the drive mechanism of the medical tool; and where a surface of the surgical side of the cup is adapted to interact with the drive mechanism such a rotary motion of the driver portion within the cup section deforms the cup, where the surface of the surgical side of the cup drives the drive mechanism upon continued deformation of the cup. 
         [0018]    In another variation, the device includes a flexible gear adapted to transfer motion from at least one rotary driver mechanism of a surgical system to a gear drive of a medical tool, the flexible gear comprising: at least one flexible spline cup having an interior working surface and a continuous exterior surgical surface where the flexible spline cup comprises a material capable of sterilization, the flexible spline cup having a shape such that the interior working surface of the flexible spline cup receives a driver of the rotary driver mechanism and the exterior surgical surface of the flexible spline cup nests within the gear drive, where rotary motion of the driver deforms, without rotating, the exterior surgical surface of the flexible spline cup such that continued deformation of the surgical surface engages the gear drive resulting in rotation of the gear drive; and a drape section extending frorn the flexible spline cup. 
         [0019]    The invention also includes a method of driving a sterile medical tool with a non-sterile surgical system during a surgical procedure while maintaining a sterility of the surgical tool, the method comprising: placing a surgical drape over the surgical system where the drape comprises a working side to engage the surgical system and a sterile surgical side, the surgical drape including at least one flexible cup having a shape such that the working side of the cup receives a drive mechanism of the surgical system creating at least one deformed portion of the cup; coupling the sterile medical tool to the surgical system by placing at least one gear of the medical tool on the surgical side of the cup; and driving the medical tool by actuating the surgical system such that the drive mechanism of the surgical system causes movement of the at least one deformed portion of the flexible cup along the gear of the medical tool. 
         [0020]    In one variation, the method further comprises removing the medical tool from the surgical drape while preserving a sterility of the medical tool. The medical tool can be subsequently re-coupled to the system without the need to re-sterilize. The method also includes coupling a second medical tool to the surgical system by placing at least one gear of the second medical tool on the surgical side of the cup. 
         [0021]    In another variation, the surgical system comprises a portable surgical system and where the method further includes encapsulating or pouching the surgical system with the surgical drape. 
         [0022]    Examples of medical systems that can be used with the methods devices and systems described herein are found in the following commonly assigned patent applications, each of which is incorporated by reference: U.S. 20060084945 Instrument Driver For Catheter Robotic System; 20080234631 Apparatus Systems and Methods for Flushing Gas from a Catheter of a Robotic Catheter System; and 20050222554 Robotic Catheter System. 
         [0023]    The systems, devices and methods described herein are intended to illustrate the various aspects and embodiments of the invention. Where possible, the combination of various aspects as well as the combinations of various embodiments is intended to be within the scope of this disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0024]    The drawings illustrate the design and utility of illustrated embodiments of the invention. in which similar elements are referred to by common reference numerals, and in which: 
           [0025]      FIG. 1A  illustrates an example of a robotic catheter manipulator (“RCM”). 
           [0026]      FIG. 1B  illustrates the inner mechanisms of a conventional RCM. 
           [0027]      FIG. 2  illustrates one variation of a medical system using an RCM to manipulate a medical tool. 
           [0028]      FIG. 3A  illustrates a variation of an RCM adapted to accommodate a variety of tool/driver modules. 
           [0029]      FIG. 3B  shows one example of a modular tool/driver assembly. 
           [0030]      FIGS. 4A to 4C  illustrate a variation of a tool/driver module with the drive mechanism removed from the driver system. 
           [0031]      FIGS. 5A  and SB illustrate a variation of a harmonic drive configuration according to the principles described herein. 
           [0032]      FIGS. 5C through 5F  illustrate an additional variation of a drive system using a cam follower type driver. 
           [0033]      FIGS. 6A through 6D  show one variation of a flexible spline cup. 
           [0034]      FIGS. 7A through 7D  illustrate variations of wave generators for use with the harmonic motor assemblies. 
           [0035]      FIG. 8A  illustrates a bottom perspective view of one example of a drive mechanism that houses a number of circular splines or spline gears. 
           [0036]      FIG. 8B  illustrates an enlarged view of a circular spline gear. 
           [0037]      FIG. 5C  illustrates an exploded view of the circular spline gear as part of a drive pulley assembly that fits within a drive mechanism. 
           [0038]      FIG. 5D  shows one variation of a drive mechanism with four drive pulley assemblies. 
           [0039]      FIG. 9A  illustrates a partial view of an RCM covered by a surgical barrier having a number of flexible spline cups. 
           [0040]      FIG. 9B  illustrates a schematic illustration of an RCM having two bays each housing a medical tool. 
           [0041]      FIGS. 10A through 10F  show variations of an RCM having a number of drive mechanism for medical tools where the drive mechanism move axially and rotationally relative to each other. 
           [0042]      FIGS. 11A and 11B  show an additional variation of the system including a drape that provides a sterile barrier between a component of an RCM and a drive system to preserve sterility when substituting a drive system on the RCM. 
           [0043]      FIG. 11C  illustrates an example of a pair of splayers or drive systems each able to rotate and axially translate relative to one another as well as an RCM where the first splayer controls a medical tool extending through a catheter coupled to a second splayer. 
           [0044]      FIGS. 12A through 12C  illustrate various configurations allowed by the modular nature of the present system. 
           [0045]      FIGS. 13A through 13C  illustrate another variation of a portable device using a flexible spline gear. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0046]    Methods, systems, and devices are described herein that improve on various drive systems that arc used with complex medical systems. The drive systems described herein employ a harmonic gear drive configuration that permits a reduction in the size of the motors used to drive the tools as well as drive systems that allow for a medical practitioner to interchange various medical tools on the medical system without compromising a sterility of the tool. 
         [0047]      FIG. 2  illustrates one example of a medical system that benefits from the methods, devices and systems described herein. In this example, the system is a robotic catheter system  26 . The system  26  can include an operator control station  2  located remotely from an operating table  22 , to which a robotic catheter manipulator (RCM)  16  and instrument or medical tool  18  are coupled. A communication link  14  transfers signals between the operator control station  2  and RCM  16 . It is noted, the medical systems within the scope of this disclosure can include stand alone systems that could be attached to a table  22  or other surgical equipment (in addition to the system illustrated in Fig.  2 ). Furthermore, variations of medical systems under this disclosure can include a single surgical motor or actuator that drives a medical tool where the surgical motor or actuator is a portable tool or is otherwise affixed to the surgical field. 
         [0048]      FIG. 3A  illustrates a variation of an RCM  16  adapted to accommodate a variety of tool/driver modules  100  (as shown in  FIG. 3B ). The interface module  100  includes a medical tool  102  comprising a drive mechanism  104  that manipulates a medical device  106 . 
         [0049]    The medical devices  106  within the scope of this disclosure can include any number of medical devices used for surgical procedures. For example, in some variations the medical device  106  is simply a steerable sheath or introducer used to deliver additional medical devices therethrough where the additional medical devices have a working end to perform a surgical, therapeutic, or diagnostic function. In additional variations, the medical device includes a steerable shaft or catheter that has a working end for performing the surgical, therapeutic, or diagnostic function. 
         [0050]    While the illustration shows a single drive mechanisms  104  variations of the present disclosure can include one or more drive mechanisms depending on the number of devices  106  or the degrees of freedom required by the particular application. 
         [0051]    The tool/driver module shown  100  also includes a driver system  110 . As discussed below, the medical tool  102  is removably engageable with the driver system. The driver system  110  includes one or more motors  112  directly engageable with the drive mechanism  104  of the medical tool  102 . 
         [0052]    As shown in  FIG. 3A , the RCM  16  is simplified since the motors, gear, belts, pulleys, cables, etc. that drive the medical tool arc no longer part of the RCM  16 . Accordingly, the RCM  16  includes open spots or bays  90  where the tool/driver modules  100  can be inserted. As noted below, RCM  16  under the present disclosure can include any number of bays  90  so that a number of medical tools  102  can be manipulated by the RCM  16 . This feature along with the modular nature of the tool/driver modules  100  allow a medical practitioner to add or subtract capability to the system by installing or removing various tool/driver modules  100 . In certain variations, the modules would be readily identifiable by the system&#39;s control unit  2  for immediate use. Such a “plug-n-play” effect increases the utility of such RCMs  16 . Different tools or medical devices might require modules  100  with different characteristics, features, or interfaces. Accordingly, a medical practitioner can readily change or add a desired tool with minimal delay. 
         [0053]    In addition, the modular nature of the RCM  16  and tool/driver module  100  allows ease of replacement of defective motors or other components. Such defective parts can be replaced. In contrast, systems in which the driver system is incorporated into the RCM will be inoperable during maintenance. 
         [0054]      FIGS. 4A to 4C  illustrate a variation of a tool/driver module  100  with the drive mechanism  104  removed from the driver system  110 . As illustrated, the driver mechanism  110  includes any number of motors  112  coupled together via a baseplate  114 . In certain variations, the baseplate  114  is secured within a bay  90  of the RCM  16 . Alternatively, the motor could be directly secured within the RCM  16  without any baseplate. In addition, any cables/wiring/or other connectors that couple the motors  112  to the RCM  16  and control station  2  are omitted for purposes of clarity. 
         [0055]    In operation, either the entire tool/driver module  100  can be inserted into a RCM  16 . Alternatively, the tool  102  or drive mechanism  104  can be removed from the module  100  so that the driver system  110  alone is inserted into (or remains in) the bays of the RCM  16 . In these latter variations, the tool/driver module  100  can include a flexible gear  130 . While the flexible gear  130  can provide several functions, primarily, the flexible gear  130  serves as a component of a harmonic drive type system. The features of the flexible gear arc discussed in detail below. 
         [0056]      FIGS. 4B and 4C  illustrates the flexible gear  130  being removed from the driver system  110 . As shown, motors  112  are secured to a baseplate  114  so that a portion of the motor extends above the baseplate  114 . In a harmonic drive type system, this portion comprises a wave generator or wave generating cam  116 . The rotation of the wave generating cam  116  of the driver system  110  is transferred through the flexible gear  130  to the drive mechanism  104  to ultimately pre-position, bend, steer, or actuate the medical device (not shown). 
         [0057]      FIGS. 5A and 5B  illustrate a variation of a harmonic drive configuration for use with the present device and system. A typical harmonic drive mechanism consists of three components, a wave generator, a flex spline, and a circular spline.  FIG. 5A  illustrates a disassembled view of the motor  112  with a wave generator  116  attached. The wave generator or wave generating cam  116  nests within a flexible spline gear  130 . Typically, the flexible spline gear comprises a shallow cup type structure with a rigid bottom and flexible sidewalls having a number of spline teeth  132  on the outer surface. The flexible spline gear  130  transfers rotation from the wave generating cam  116  to a circular spline or gear  116  that is part of the drive mechanism  104  of the medical tool. The circular gear  140  is typically a rigid ring with gear teeth  142  on its inner surface. 
         [0058]      FIG. 5B  shows a variation of the interaction between the wave generating cam  116  against the flexible spline gear  130  to drive the circular spline or gear  140 . The elliptical nature of the wave generating cam  116  deforms the flexible spline gear  130  at opposing ends. In the illustrated variation, the ends of the wave generating cam  116  as well as the interior surface of the wave spline gear  130  are smooth. However, one or more of these surfaces can optionally include teeth or other features to assist in driving the system. The exterior surface of the flexible spline  130  includes a number of spline teeth  132 . These spline teeth  132  engage an interior surface of the circular gear  140  that can have a number of gear teeth  142 . When assembled, the flexible spline  130  mounts onto the wave generating cam  116  so that the wave generating cam  116  fits within the cup structure of the flexible spline  130 . The circular gear  140  is then mounted onto the flexible spline  130  so that the spline teeth  132  on the outer surface of the flexible spline  130  mate with the gear teeth  142  on the inner surfuce of the circular gear or circular spline  140 . The elliptical nature of the wave generating cam  116  deforms the flexible spline  130  to engage the circular spline  140  at two regions on opposite sides of the flexible spline  130 . The wave generating cam  116  is then driven in a circular motion causing the deformed portion of the flexible spline  130  to move or orbit about its axis. Conventional harmonic configurations require either the flex spline or the circular spline to be constrained from rotating. This permits rotary motion of the wave generating cam  116  to transfer to the other non-rotating member. In one variation of the present configuration, the flex spline  116  does not rotate and is maintained in a stationary position. Thus, the movement of the wave generating cam  116  causes movement in the spline gear  140 . The harmonic drive configuration provides a tool/driver module  100  with inherent gear reduction and zero backlash. 
         [0059]    The number of spline teeth  132  on the flexible spline  130  is different from the number of gear teeth  142  on the circular spline gear  140 . The difference in the number of spline teeth  132  and gear teeth  142  cause the circular gear  140  to rotate a slight amount for every full rotation of the wave generating cam  116 . 
         [0060]    As the motor  112  rotates the wave generating cam  116 , the deformed portion of the flexible spline  130  moves in a wave-like motion causing meshing of the spline teeth  132  against the gear teeth  142  of the circular gear  140  at their two equidistant points of engagement. This meshing progresses in a continuous rolling fashion. It also allows for full tooth disengagement at the two points along the minor axis of the Wave Generator. Since the number of teeth are different, and because full tooth disengagement is made possible by the elliptical shape of the wave generator cam  116 , each complete revolution of the wave generator cam  116  a displacement equal to the difference in the number of teeth, This displacement is always in the opposite direction of the rotation of the wave generating cam  116  as shown by arrows  118  and  120  in  FIG. 5B . In one variation, the difference in the number of spline teeth  132  and gear teeth  142  is two (namely that there arc two fewer spline teeth  132  than gear teeth  142 .) However, additional configurations are within the scope of this disclosure. 
         [0061]    Another benefit of the present configuration is that the tool/driver module  100  is intended to be disassembled and reassembled by the user during operation. As noted above, the flexible spline gear  130  itself can form a sterile barrier. Thus the driver system  110  and flex spline gear  130  can remain in place while the circular spline gear  140  is integrated into the drive mechanism  140  and can be replaced without comprising the sterile field of the surgical procedure. 
         [0062]      FIGS. 5C to 5F  illustrate an alternate gear drive system  110 . In this variation, a motor  112  is coupled to and rotates a camshaft  124  that drives a cam follower  126 .  FIG. 5D  shows a top view of the cam follower  126  as seen from line  5 D- 5 D in  FIG. 5C . The center of the cam follower  127  can be offset from an axis or center of rotation of the motor  123 . As shown in  FIG. 5E , rotation of the motor  112  causes the cam shaft  124  to rotate and drive the cam follower  126  about the axis of the motor  123  rather than about the center of the cam follower  127 . Accordingly, the cam follower  126  moves about an orbital path  121  in either direction  117  rather than only a rotational path about its own center  127 . The camshaft  124  and cam follower  126  can include any number of bearings or bearing surface at the interface to allow the camshaft  124  to rotate independently of the cam follower  126 . Alternatively, in an additional variation, the two parts could be affixed together. 
         [0063]      FIG. 5F  shows a variation of a gear drive system  110  having a flexible spline  130  located over the cam follower  126 . As discussed herein, the exterior of the flexible spline  130  includes a number of spine teeth (not shown) that engage a number of gear teeth  142  located on a circular spline gear  140 . The orbital rotation  121  of the cam follower  126  moves the flexible spline  130  in an x-y direction (along the inner perimeter of the circular spline gear  140 ) so that it can engage the interior gear teeth  142  of the spline gear as the motor  112  drives the camshaft  124 . As noted herein, the flexible spline  130  can include a barrier portion  137  having a flexure area  139  that accommodates movement of the flexible spline  130  in the x-y direction relative to the barrier portion  137 . At the same time, the flexible spline  130 , being affixed to the barrier  137  via the flexure area  139  does not rotate. The system  110  can be designed to select a rate of rotation of the spline gear  140  relative to the rotation of the flexible spline gear. The circular spline gear  140  will rotate relative to the rotation of the motor shaft  112  by a multiple of spline teeth/gear teeth. In other words, the circular spline gear  140  will rotate N times as much as the motor shaft where N=# of spline teeth/# of gear teeth. 
         [0064]      FIGS. 6A through 6D  show one variation of a flexible spline gear  130 .  FIGS. 6A and 6B  show perspective and side views of the spline gear  130  as having a cup section  134  with a number of spline teeth  132  on an outer surface of the flexible spline  130 . Once sterilized, this outer surface forms a working surgical surface or surgical side that can enter the sterile filed of the operating room. Accordingly, the surgical side  138  can extend from the cup shape  134 . In additional variations, the surgical surface  138  of a flexible spline gear  130  may not have teeth but can be formed into a surface that engages the circular spline for transmission of a rotational force. In addition, the cup shape  134  can be fabricated from a material that is flexible and can withstand an acceptable sterilization process (e.g., nylon, plastic, a flexible metal, etc.).  FIG. 6C  shows a bottom perspective view of a flexible spline gear  130 . As discussed previously, the working side  136  of the spline gear  130  typically contacts a wave generator or other non-sterile environment. The working surface can comprise a smooth surface or can have varying textures to increase gripping of the wave generator cam. 
         [0065]      FIG. 6D  illustrates a number of spline gears  130  forming part of a sterile drape or surgical barrier  137 . The surgical barrier  137  can include any number of flexible spline gears  130  (where such spline gears  130  can be formed from or in the barrier  137 ). Alternatively, in additional variations, the spline gears  130  could be assembled into the surgical barrier  137 . In certain variations, the surgical barrier  137  can be made from a different material than the spline gear  130  or can have different properties (e.g., stiff, absorbent, etc.). However, to maintain the benefits of the tool/driver module described above, the surgical barrier  137  as well as the spline gears  130  must be robust enough to withstand repeated placement and removal of the drive mechanism onto the spline gears  130  without losing or compromising sterility of the surgical field. In addition, the surgical barrier  137  can include any number of features to accommodate relative motion between adjacent groups of spline gears  130  (and ultimately the drive mechanism that are to be attached thereto). For example, the surgical barrier can include an area of increased flexure  139  to accommodate relative movement or rotation of the adjacent groups of spine gears  130  and drive mechanisms. The area of increased flexure  139  can include an accordion or corrugated section of the barrier  137 . 
         [0066]      FIGS. 7A through 7D  illustrate variations of wave generators  116  for use with the motors  112  of the driver system  110  discussed above. Typically, the wave generator  116  the wave generator  116  can be directly driven by a motor  112 . Alternatively it could be driven by any rotary axis motion, including a non-direct means including any configuration of gears, pulleys, etc. However, placement of motors underneath the drive mechanism  104  and in engagement with the wave generator  116  allows the motor to float with the tool/driver module  100  to achieve the benefits discussed above. 
         [0067]    In any case,  FIGS. 7A and 7B  show respective perspective and side view of variation of a wave generator cam  116  having point contacts. In this example, the wave generator or wave generator cam  116  can be a sufficiently rigid material (e.g., a stainless steel member) with a spherical ball bearing  122  as a dual lobe on each side. The spherical ball-bearing configuration lends to point contacts on opposite ends of the wave generator cam  116  to engage a flexible spline. These point contacts reduce the force required to mate the flex spline/wave generator with the circular spline. However, because the point contacts also result in less contact (i.e. less teeth meshing) between the flexible spline and the circular spline gear, this configuration results in less drive force or a lower load rating. 
         [0068]    Accordingly, in additional variations, the tool/driver module  100  can incorporate a more traditional elliptical shape (as shown in  FIG. 7C ). This traditional shape results in a larger contact area between the wave generator and the flexible spline. The larger contact area allows for a higher drive force (i.e. a higher load rating). In yet an additional variation (as shown in  FIG. 7D ), a wave generator configuration can include rollers or roller bearings on either end. This configuration also increases the contact area between the wave generator and spline gear. While the increased contact area provides for higher load rating, it also requires a higher force to mate the flexible spline gear to the wave generator. Clearly, any number of variations of the shape and configuration of the wave generator cam arc within the scope of this disclosure. 
         [0069]      FIG. 8A  illustrates a bottom perspective view of a variation of a drive mechanism  104  that houses a number of circular splines or spline gears  140 . The spine gears  140  are rotatable within the drive mechanism  104  to control a medical device (not shown) coupled to the drive mechanism  104 .  FIG. 8B  illustrates an enlarged view of a circular spline gear  140  showing the gear teeth  142  as described above. As illustrated, the circular spline gear  140  can have any number of features  144 ,  146  that assist in retention of the circular spline gear  140  within the drive mechanism  104 . 
         [0070]      FIG. 8C  illustrates an exploded view of the circular spline gear  140  as part of a drive pulley assembly  150  that fits within a drive mechanism  104 . In this variation, the circular spline gear  140  functions as a lower drive pulley that receives a cable component  160 . This variation of the drive pulley assembly  150  also includes an upper pulley  152  that includes an extension or protrusion  154  (in this example a rounded rectangular extension) that inserts directly into the circular spline gear  140  (lower drive pulley). In this manner, the circular spline gear  140  rotates the upper pulley  152  when driven by the flexible spline gear. The upper pulley  152 , being coupled to the cable component  160  (e.g., using screws that pass through slots  144  in the upper pulley component  152 ) then rotates the cable component  160  to cause actuation steering, or other movement of a medical device coupled to the drive mechanism  104 . The cable component  160  can include a cutout  162  formed to hold a crimp ball at the end of an actuation cable. Alternatively, the cable component  162  can drive the circular spline member to drive any rotary device including driving robotic end effectors, or even liner motion through a rack and pinion drive. 
         [0071]      FIG. 8D  shows one variation of a drive mechanism  104  with four drive pulley assemblies  150 . The drive pulley assemblies  150  each include an actuation clement (not shown) that is coupled to cable component  160 . The actuation element couples to a medical device  106  via tracks  158  within the drive mechanism  104 . The actuation elements (also known as control elements) can comprise solid wires made from materials such as stainless steel, which are sized for the anticipated loads and geometric parameters of the particular application. The actuation elements can be coated with materials such as a Teflon™ fluoropolymer resin from DuPont of Wilmington, Del. to reduce friction forces. Additional variations of such drive mechanisms that can be used with the devices, methods, and systems described in this disclosure are found in the commonly assigned applications referenced above. 
         [0072]      FIG. 9A  illustrates a partial view of an RCM  160  covered by a surgical barrier  137  having a number of flexible spline gears  130 . As shown, the modular nature of the tool/driver modules permits the driver system  100  to be nested or seated in bays  90  of the RCM  16  and beneath the surgical barrier  137 . The drive mechanism  104  of the medical tool  102  can be removably coupled over the spline gears  130  to engage the medical tool  102  with the RCM  16  and driver system  110 . In the illustrated variation, the medical tool  102  includes two drive mechanism  104 . In such a variation, one drive mechanism could couple to a sheath, While the other can couple to a guide or other medical device. However, any number of combinations or medical devices are within the scope of this disclosure. 
         [0073]      FIG. 9B  illustrates a schematic view of an RCM  16  having two bays  90  each housing a medical tool  102 . As shown by arrow  170  the medical tools can move in an axial direction along the RCM  16  relative to one another. Alternatively, or in addition, the tools  102  can rotate relative to one another as indicated by arrows  172 , and  174 . As discussed above, placement of the motors directly beneath the medical tool  102  facilitates the ability to rotate the tools relative to each other. In addition, the entire RCM  16  can be rotated (as well as moved) with the tools  102 . 
         [0074]      FIG. 10A  shows a variation of an RCM  16  having a number of drive mechanism  110  that accept medical tools  102  where the drive mechanism  110  are able to move axially relative to each other. As shown, the drive mechanism  110  (either with or without a medical tool  102 ) can be coupled to the RCM  16  to allow for modular medical tools and drive mechanisms. In this variation, the RCM  16  includes one or more rails  180  allowing for guides or slides  182  on a base  114  of the drive mechanism  110  to couple thereto. The rail guides  182  allow for releasable coupling of the medical tool and/or drive mechanism  110 .  FIG. 10B  illustrates the medical tool  102  and rails  180  of  FIG. 10A  without the RCM for sake of illustration. As shown, the base  114  of the drive mechanism  110  includes rail guides  182  that slide along the rails  180  allowing each medical device to move independently move as shown by element  170 . 
         [0075]    As discussed above, the use of small motors allows the entire drive mechanism  110  to be rotated relative to the RCM and other drive mechanism about an axis  172  (the axis can be offset from an axis of the RCM). The ability to independtly rotate the various medical tools  102  relative to one another permits improved steering, positioning, or actuation of any number of medical devices. The axial movement of each base  114  can be controlled using a screw-drive type configuration. Alternatively, the rail guides  182  and rails  180  can function as linear drive motors where the rail functions as a stator  180  that drives the rail guides  182 . 
         [0076]      FIG. 10C  illustrates another variation of a system for use with an RCM where the medical tools  140  are axially and rotationally positionable relative to each other. In this variation, the RCM (not pictured) is configured to couple to the base  114  in order to provide a linear drive motor system to position the medical tools  102 . Linear drives typically include a stationary platen or stator (similar to a stator in a rotational motor) and a slider or forcer (similar to a rotor in a rotational motor) that moves along the stator. In this variation, the stator  186  is affixed to the RCM (not shown) and the base  114  includes forcer components  184 . 
         [0077]    Thus, the drive mechanism  114  (being affixed to the base  184 ) is driven with an AC or DC current that is applied to the stator  186 . The linear configurations discussed in reference to  FIG. 10B  and IOC allow for non-contact operation with non-wearing parts. This allows for placement of a drape or barrier between the base  114  and rail  180  or stator  186 . As discussed herein, this barrier permits maintaining a sterile field when replacing drive systems  114  on the RCM. 
         [0078]      FIG. 10D  illustrates another aspect of the drive mechanism  110  as having a positioning motor  188 . In this variation, the positioning motor  188  engages the base  114  to rotate the drive mechanism  110  and medical tool  102  about an axis as shown by arrows  172 . The interface between the positioning motor  188  and base  114  can be any commonly used interface (pinion gear, frictional interface, etc.)  FIG. 10E  illustrates a rear view of the assembly of  FIG. 10D . As shown, the positioning motor  188  engages a concave track  190  in the base  114  to rotate the medical tool  102  about an axis.  FIG. 10F  illustrates a partial view from a bottom perspective of a drive mechanism  110  having a positioning motor  188  coupled to two concave tracks  190  in a base  114 . The rotation of the base and medical tool can occur about an axis of the RCM or can occur about an axis that is offset from the axis of the RCM. For example, the depths and/or length concave track  190  can vary to modify the rotation of the drive mechanism  110  and medical tool  102 . 
         [0079]      FIGS. 11A and 11B  show an additional variation of the system described herein. In this variation, the rail  180  or stator  186  can include a drape  192  to provide a sterile barrier between the RCM  16  and the surgical field. Accordingly, the medical tool  102  and drive mechanism  110  along with the base  114  can be replaced during a surgical procedure while maintaining sterility when coupled to the RCM  16 . As shown, the surgical barrier  192  can include a drape portion that encases the RCM  16 . In additional variations, the surgical barrier  192  can be a fitted material that fits over the rail  180  or stator  186 . In such a case the surgical barrier comprises a material (such as PTFE) that does not interfere with the interaction between the base  114 , rail  180 , rail guide  182 , stator  186 , and/or forcer component  184 . 
         [0080]      FIG. 11C  illustrates a variation of the system shown in  FIG. 11B  (though the concept is applicable to any system described herein) where a pair of splayers or drive mechanism  104  each able to rotate and axially translate relative to one another as well as an RCM  16  (in this case the RCM is underneath a drape  192 ) where the first mechanism  104  controls a medical tool  102  extending through a catheter  103  coupled to a second mechanism  104 . In this variation, the distal portion of the catheter  103  is shown curved (“S” shaped; i.e., a flexible distal portion). Typically, the distal portion of the catheter  103  extends within the anatomy of a patient. The second drive mechanism  104  coupled to the catheter  103  navigates the catheter  103  to the desired site. The first drive mechanism  104  controls a medical tool or device  102  that can exit from the distal end of the catheter  103  and can access the intended target site. The first drive mechanism  104  can actuate or control the medical device  102  interpedently of the catheter  103 . For example, the first drive mechanism  104  and drive system  110  can rotate or translate the medical tool  102  as shown by arrows  170  (representing axial translation relative to the catheter and/or RCM) and  172  (representing rotational movement relative to the catheter and/or RCM). 
         [0081]      FIGS. 12A through 12C  illustrate various configurations allowed by the modular nature of the present system. The RCM&#39;s  16  ability to accept modular drive mechanism  110  allows the user to add or subtract robotic capability by simply installing or removing drive mechanisms  110  modules. The modules are designed to operate like a cartridge, meaning that they can easily be attached and detached by the operator. The modules can have “plug-n-play” capability that allow quick installation to the base RCM  16  where the system recognize the module automatically. Different robotic tools and catheters may require the varying modules, each having different functions and interfaces, such as linear and rotational displacement features. As shown in  FIGS. 12A and 12B , the modules can be loaded from the top, bottom, sides, front, or back of the RCM. The modules  110  simply dock into the bays  90  the RCM  16 . Another benefit offered by the drive systems described herein is that each independent drive mechanism  110  can translate along a common axis  178  of the RCM  16  (typically the axis that runs along a length of the RCM  16 .) The modular drive systems  110  can also independently rotate about the same common axis as shown by arrow  172  in order to provide additional degrees of freedom to the surgical tool or catheter that is coupled to the drive system  110 . As illustrated the modular design of the RCM  16  permits !caving some bays empty. 
         [0082]      FIGS. 13A through 13C  illustrate another variation of a device according to the present disclosure. In this variation, the device  200  comprises a portable or other tool that does not require robotic insert or actuation. In other words, the modular device  200  can be standalone or one that is attached to another structure (e.g., a bed, frame, etc.) and then coupled (via wireless or via a cable) to a control system. Although the present example shows a medical tool  102  comprising a grasper, any number of medical tools can be incorporated with the design (e.g., rotary drill, deburring device, cutters, shavers, etc.) Commonly assigned U.S. provisional application no. 60/902,144 discloses a number of additional medical devices or end effectors that can be implemented into the present design. 
         [0083]      FIG. 13A  shows the medical tool  102  coupled to a tool component  164  (as shown in  FIG. 13C ) that mates with a circular spline gear  140 . In this variation, the gear  140  mates with a flexible spline  130  (but not shown in  FIG. 13A ) that engages the circular gear  140 . The remainder of the flexible spline  130  comprises a surgical barrier  137 , which in this variation comprises a pouch or an encasement that provides a sterile barrier to the motor assembly located therein. As shown, the barrier  137  can include a handle portion  156  or other section that allows manipulation or fixation of the tool  200 . 
         [0084]      FIG. 13B  illustrates an exploded view of the motor unit  112  wave generating cam  116 , surgical barrier  137 , and circular spline gear  140 . As shown, the flexible spline gear  130  is located at an end of the barrier  137  and includes a number of spline teeth  132  that engage a number of gear teeth located within the circular gear  140 .  FIG. 13B  also shows use of an actuator motor  204 . If more than one degree of actuated motion is desired, a hollow shaft motor  112  can be used. The hollow shaft motor  112  in conjunction with a lumen through the center of the wave generating cam  116  gives the ability to send a plurality of actuators through the center of the drive assembly. The flex spline gear  130  could be designed to allow for linear, rotary, or ballooning motion, or incorporate a second smaller diameter flex spline while still maintaining the sterile barrier. So while the original harmonic drive motor  112  actuates one motion (articulation of a catheter, or roll of the tool, etc.), the secondary actuator  204  s could be used for any number of motions. For example the medical device  102  can be rotated about the tools  200  longitudinal axis, where the rotational motion is driven by the harmonic drive motor  112 , wave generating cam  116 , flexible spline gear  130  and circular spline gear  140 . The secondary actuator  204  can drive the gripper  102  as shown. Alternatively, the secondary actuator  204  could drive any other type of motion depending upon the application. 
         [0085]    As illustrated, the tool  200  permits driving a medical device  102  using a single motor. Since the motor is difficult or impractical to sterilize, the surgical barrier surrounds the entire motor assembly. Thus the entire assembly  200  is sterile. The assembly could be mounted on a small set-up joint (as disclosed in the above referenced commonly assigned patents and applications). In another variation, the device  200  can be sized appropriately so that it is insertable into a patient. 
         [0086]    Although the methods and devices disclosed herein may be particularly useful in medical applications, one of ordinary skill in the art having the benefit of this disclosure would appreciate that such methods and devices may also be applicable generally in other robotic applications. As used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a member” is intended to mean a single member or a combination of members, “a fluid” is intended to mean one or more fluids, or a mixture thereof. Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above.