Patent Publication Number: US-8968333-B2

Title: Support assembly for robotic catheter system

Description:
RELATED APPLICATION DATA 
     The present application is a continuation of U.S. patent application Ser. No. 11/173,812, filed Jul. 1, 2005, now issued as U.S. Pat. No. 7,789,874 on Sep. 7, 2010, which claims the benefit under 35 U.S.C. §119 to U.S. provisional patent application Ser. Nos. 60/677,580, filed May 3, 2005, and 60/678,097, filed May 4, 2005, which are incorporated by reference into the present application in their entirety. 
     The present application is also related to U.S. patent application Ser. No. 11/073,363, filed Mar. 4, 2005, now issued as U.S. Pat. No. 7,972,298 on Jul. 5, 2011, which claims the benefit under 35 U.S.C. §119 to U.S. provisional patent application Ser. Nos. 60/550,961, filed Mar. 5, 2004, 60/553,029, filed Mar. 12, 2004, 60/600,869, filed Aug. 12, 2004, and 60/644,505, filed Jan. 13, 2005. The foregoing applications are also incorporated by reference into the present application in their entirety. 
    
    
     FIELD OF INVENTION 
     The invention relates generally to robotically controlled catheter systems, and more particularly to support arm assemblies for mounting and positioning an instrument driver to a operating table in a robotic catheter system. 
     BACKGROUND 
     Robotic catheter systems and devices are well suited for use in performing minimally invasive medical procedures, as opposed to conventional techniques wherein the patient&#39;s body cavity is open to permit the surgeon&#39;s hands access to internal organs. For example, there is a need for a highly controllable yet minimally sized system to facilitate imaging, diagnosis, and treatment of tissues which may lie deep within a patient, and which may be accessed via naturally-occurring pathways such as blood vessels or the gastrointestinal tract, or small surgically-created pathways. 
     SUMMARY OF THE INVENTION 
     In accordance with various embodiments of the invention, a support assembly is provided for supporting a remotely-controlled instrument driver relative to the patient. In one embodiment, a support assembly for supporting a remotely-controlled instrument driver, including a first member, a second member for supporting the instrument driver, and an interface assembly for allowing the second member to rotate relative to the first member about a first axis, and for allowing the second member to rotate relative to the first member about a second axis that forms an angle relative to the first axis, wherein the interface assembly comprises a ball that is rotatable relative to the first member, and a shaft extending through the ball, the shaft configured for coupling to the second member. 
     In one embodiment, the support assembly comprises a base removably attachable to an operating table, and an actuator assembly coupled to the base. In one embodiment, the base comprises a clamp having a clamp body portion configured to pivot relative to the base. The actuator assembly includes a rotable member and a brake configured to selectively allow rotation of the rotatable member about a first axis, which is preferably substantially perpendicular to the operating table. The actuating assembly further includes an actuator, such as, e.g., a solenoid. 
     A first extension member has a first end mounted to the rotatable member, such that the brake selectively allows rotation of the first extension member about the first axis. By way of non-limiting example, the brake may be configured to prevent rotation of the first extension member about the first axis unless it is electronically activated, in which case it allows such rotation. A second extension member is coupled to a second end of the first extension member via an interface assembly configured to selectively allow rotation of the second extension member about a second axis, which may be substantially parallel to the first axis, upon activation of the actuator. In one embodiment, the interface assembly is further configured to also allow rotation of the second extension member about a third axis, which is preferably substantially orthogonal to the second axis, upon activation of the actuator. In such embodiment, the second extension member may comprise a force-resisting mechanism to resist rotation of the second extension member about the third axis. 
     In one embodiment, the interface assembly comprises a shaft having a first end coupled to a ball joint and a second end coupled to the second extension member. A lever arm extends through the first extension member, the lever arm subjected to a biasing force to thereby retain the ball joint in a locked position, the actuator assembly configured to overcome the biasing force upon activation of the actuator, thereby allowing the ball joint to move to an unlocked position. The ball joint is preferably oriented within the interface assembly to be in an unlocked position due to gravitational force in the absence of being constrained in a locked position by the lever arm. In one embodiment, the lever arm is operatively coupled with a leveraging mechanism configured to apply a leveraged force on the ball-joint. In preferred embodiments, the levering mechanism causes the lever arm to apply a leveraged forced on the ball joint in a range between about 5:1 to about 20:1, and in one embodiment, at a ratio of about 15:1. 
     In various embodiments, the second extension member comprises a first end attached to the second end of the shaft, with a first sprocket rotatably attached to the first end and fixed to the first extension member, such that the first sprocket rotates in proportion to rotation of the second extension member about the third axis. A second sprocket is rotatably attached to a second end of the second extension member, with the first and second sprockets linked so that the second sprocket rotates in proportion to rotation of the first sprocket. The support assembly further comprises a support member configured for mounting and carrying the instrument driver, wherein the support member may be coupled to the second sprocket in a manner such that an instrument driver mounted to the support member remains in a substantially same orientation relative to the operating table, regardless of rotation of the second extension member relative to the interface assembly. By way of one example, a support member brake housing is fixedly attached to the second sprocket, the brake housing defining an aperture facing away from the operating table that rotatably seats the instrument driver support member. In this manner, the instrument driver support member may be selectively rotated about an axis defined by the brake housing aperture, wherein the axis remains in the same orientation relative to the operating table, regardless of rotation of the second extension member about the interface assembly. 
     In one embodiment, rotation of the first extension member about the first axis is prevented unless the actuating assembly brake is electronically activated, and rotation of the instrument driver support member about the support member brake aperture is prevented unless the support member brake is electronically activated. The actuator is preferably also electronically activated. Preferably, the actuating assembly brake, instrument driver support member brake, and the actuator are all activated by a common control signal. In one embodiment, the control signal is activated by depression of a button located on the instrument driver support member. 
     In one embodiment, an adjustable mounting interface is carried on the instrument driver support member and configured for mounting an instrument driver in a selectable pitch relative to the operating table. A biasing spring may be carried on the support member and configured to at least partially counterbalance a cantilevered load upon the instrument driver mounting interface caused by the weight of an instrument driver mounted upon it. 
     Other and further embodiments and aspects of the invention will become apparent upon review of the following detailed description in view of the illustrated embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  illustrates a robotic catheter system in accordance with one embodiment; 
         FIG. 2  illustrates a robotic catheter system in accordance with another embodiment; 
         FIG. 3  illustrates one embodiment of a support assembly for mounting an instrument driver to an operating table; 
         FIG. 3.1  is a perspective isometric view of another embodiment of a support assembly for mounting an instrument driver to an operating table; 
         FIG. 3.2  is an exploded isometric view of the support assembly of  FIG. 3.1 ; 
         FIG. 3.3  is a cut-away side sectional view of a table clamp used in the support assembly of  FIG. 3.1 ; 
         FIG. 3.4  is a cut-away side sectional view of a solenoid and brake unit used in the support assembly of  FIG. 3.1 ; 
         FIG. 3.5  is an exploded isometric view of a brake assembly used in the solenoid and brake unit of  FIG. 3.4 ; 
         FIG. 3.6  is a cut-away side sectional view of an arcuate vertical extension member used in the support assembly of  FIG. 3.1 ; 
         FIG. 3.7  is a perspective isometric view of a ball/shaft interface used to movably a horizontal extension member to the arcuate extension member of  FIG. 3.6 ; 
         FIG. 3.8  is a cut-away side sectional view of the horizontal extension member in the support assembly of  FIG. 3.1 ; 
         FIG. 3.9A  is partially cut-away, perspective isometric view of an instrument driver mounting shaft and handle assembly used in the support assembly of  FIG. 3.1 ; 
         FIG. 3.9B  is a perspective isometric view of the instrument driver mounting shaft and handle assembly of  FIG. 3.9A ; 
         FIG. 3.10A  is a perspective isometric view of an instrument driver as mounted to one embodiment of a support assembly; and 
         FIG. 3.10B  is a reverse perspective isometric view of the structures depicted in  FIG. 3.10A . 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Referring to  FIG. 1 , one embodiment of a robotic catheter system  32 , includes an operator control station  2  located remotely from an operating table  22 , to which a instrument driver  16  and instrument  18  are coupled by a instrument driver mounting brace  20 . A communication link  14  transfers signals between the operator control station  2  and instrument driver  16 . The instrument driver mounting brace  20  of the depicted embodiment is a relatively simple, arcuate-shaped structural member configured to position the instrument driver  16  above a patient (not shown) lying on the table  22 . 
     In  FIG. 2 , another embodiment of a robotic catheter system is depicted, wherein the arcuate-shaped member  2  is replaced by a movable support-arm assembly  26 . The support assembly  26  is configured to movably support the instrument driver  16  above the operating table  22  in order to position the instrument driver  16  for convenient access into desired locations in a patient (not shown). The support assembly  26  in  FIG. 2  is also configured to lock the instrument driver  16  into position once it is positioned. 
       FIG. 3  provides a closer view of the support assembly  26  depicted in the embodiment of  FIG. 2 . The support assembly  26  comprises a series of rigid links  36  coupled by electronically braked joints  34 . The joints  34  allow motion of the links  36  when energized by a control system (not shown), but otherwise prevent motion of the links. The control system may be activated by a switch (e.g., a footswitch), or computer interface. In another embodiment, the rigid links  36  may be coupled by mechanically lockable joints, which may be locked and unlocked manually using, for example, locking pins, screws, or clamps. The rigid links  36  preferably comprise a light but strong material, such as high-gage aluminum, shaped to withstand the stresses and strains associated with precisely maintaining a three-dimensional position of the approximately ten pound weight of a typical embodiment of the instrument driver  16  once the position of the link  36  is fixed. 
     FIGS.  3 . 1 - 3 . 10 B depict another embodiment of the support assembly, also designated by reference no.  26 . Referring to  FIGS. 3.1  and  3 . 2 , in this embodiment, a mechanical operating table interface  1  includes a pair of clamp members  89  to removably attach the support assembly  26  to the operating table  22  (shown in phantom outline). As explained in greater detail in conjunction with  FIG. 3.3 , the clamp members  89  include a lower clamp toe configured to pivot outwards for ease in engaging a rail (not shown) on an edge of the operating table  22 . 
     The main body of the mechanical interface  1  is fixed to the housing of a solenoid and brake unit  3 . A proximal base of an arcuate, vertical extension member  11  is coupled to, and selectively rotable about a central axis of, the solenoid and brake unit  3 . The vertical extension member  11  bends through an angle of approximately 90°, and has a distal end rotatably coupled, via a pan-rotate interface  13 , to a first end of a further extension member  15 . As explained in greater detail in conjunction with  FIG. 3.6 , the pan-rotate interface  13  selectively allows extension member  15  to both rotate about an axis of a distal extending shaft  55  (seen in  FIG. 3.2 ), as well as pan laterally along an arc defined by lateral movement of the shaft  55  through a pan slot  111  defined by the housing  121  of the pan-rotate interface  13  in a plane that is preferably parallel to a plane defined by the operating table. 
     A distal brake unit  19  is coupled to a sprocket comprising the second end of extension member  15 , the sprocket being rotatably coupled to the housing of the extension member  15 , as described in further detail below. The brake unit  19  is configured for selectively allowing rotation of an instrument driver support shaft  17  relative to the brake unit  19 , the support shaft  17  carrying a pivotable mounting interface  21  for attaching the instrument driver (not shown). The support shaft  17  further includes a handle portion  23 , which has a button  24  for electronically actuating the respective electronic brake and solenoid in unit  3 , as well as the distal brake  19 , to thereby allow the afore-described motions of the various components of the assembly  26 . Cable holder brackets  113  are provided along the exterior of the support shaft  17 , pan-rotate interface  13 , and solenoid and brake unit  3 , respectively, for attaching a power/control cable from the instrument driver (not shown). One a more control cables (not seen) also extend internally within the various components of the assembly  26  from the distal end button  24  to the distal brake  19  and to the solenoid and brake unit  3 . 
     The support assembly  26  is configured to facilitate easy positioning and repositioning of a remotely controlled instrument driver over the operating table  22 . When the button  24  on the handle portion  23  is depressed, the respective electronic brakes and solenoid of the assembly  26  allow the respective interfaces to move freely relative to each other, constrained only by the interface configurations, to allow for repositioning of the handle  23  and associated instrument driver support shaft  17  relative to the operating table  22 . When the button  24  is not depressed, the respective brakes prevent any further movement of the support shaft  17 , wherein the support assembly  26  is configured to provide a high level of mechanical stability. In one embodiment, upon activation of the solenoid and release of the brakes, the distal brake unit  19  is configured to allow an approximately 135 degree range of motion about the rotation axis  125  of the brake unit  19 , the pan-rotate interface  13  is configured to allow an approximately 140 degree range of motion rotation about the rotational axis of the shaft  55  as well as approximately 110 degrees of pan rotational motion through the plane defined by the pan slot  111 , and the vertical extension member  11  is configured to allow an approximately 350 degree range of rotational motion relative to the solenoid and brake unit  3 , which is configured to be coupled to an operating table. 
     As shown in  FIG. 3.3 , the mounting clamps  89  each generally comprise a fixed body portion  33  having a mating surface  101 , and upper and lower clamp toe portions  115  and  99 , configured for attachably coupling to a rail (not shown) disposed on an edge of the operating table  22 . The lower clamp toe portion  99  is preferably fastened to the swinging clamp body portion  29 , with a threaded locking member  25  used to tighten/loosen the lower clamp toe portion  99  against the rail to secure/release the clamp  89  thereto or therefrom. For ease in loading the assembly  26  onto an operating table rail, the mating surface  101  of the fixed clamp body portion  33  is indented to seat a fulcrum rod  27  that rides against a side of the rail, and the swinging clamp body portions  29  of the clamps  89  may be individually pivoted ( 95 ) about the pin member  31  to rotate away from the operating table rail (not shown) to facilitate extending the upper clamp toe member  115  onto the rail with easy access to the mating surface  101 . In the depicted embodiment, the swinging clamp toe bodies  29  are spring  97  biased to rotate ( 95 ) in this manner until the mating surface  101  has been positioned against the operating table rail (not shown), subsequent to which the swinging clamp toe bodies  29  may be manually rotated about the pin  31  and wound into position interfacing with the operating table rail (not shown) with the threaded locking member  25 , as depicted in  FIG. 3.3 . 
     Referring to  FIG. 3.4 , the solenoid and brake unit  3  comprises an outer housing  103  and an inner member  45  that is rotatably mounted within the housing  103 . The inner member includes a distal facing surface  117 , configured to receive a proximal mounting interface  94  of the vertical extension member  11  (See  FIG. 3.2 ). In this manner, the extension member  11  (See  FIG. 3.2 ) is rotatable about a longitudinal axis  119  of the solenoid and brake unit  3 . A brake assembly  39  is biased to prevent rotation of member  45  (and, thus, of extension arm  11 ), unless electronically actuated to release the member  45 . In  FIG. 3.5 , the brake  39  is depicted, along with a flex-disk interface  49  and a clamp  47 , which couples firmly to the rotatable frame member  45 . The flex-disk interface  49  allows for some axial movement between the clamp  47  and the brake  39 , without significant rotational “slop” commonly associated with more conventional spline interfaces. Thus, manual rotation of the vertical arm  11  about an axis which may be substantially orthogonal to the operating table  22  (i.e., for positioning an instrument driver  16  mounted on the support shaft  17  relative to a patient positioned on the operating table  22 ) is selectively allowed by electronic activation of the brake  39  when the button  24  is depressed into the handle  23 . 
     Referring back to  FIG. 3.4 , a top end of the unit  3  includes a plunger  41 , that is biased by a set of helical springs  43  to push away from the housing  103  of the solenoid and brake unit  3 , into an interior bore of the extension member  11 . When a solenoid  35  located in a lower portion of the housing  103  is electronically activated, it pulls a pull-rod  37 , which in turn pulls the plunger  41 , in a compressive direction against the springs  43 , toward the housing  103  of the solenoid and brake unit  3 . 
     As shown in  FIG. 3.6 , the vertical extension member  11  has a hollow interior to accommodate an arcuate lever  57  configured to compress and lock into place the pan-rotate interface  13  when rotated counterclockwise about a pivot pin  61  within, and relative to, the vertical extension member  11  as the plunger  41  (see  FIG. 3.4 ) is pushed upward away from the housing  103  (see  FIG. 3.4 ) by the spring  43  load. With the plunger  41  pushed upward, the ball  53  is placed into compression between the toe  130  of the arcuate lever  57  and a contoured surface  131  coupled to the base of the pan-rotate interface  13  housing  121 . The ball  53 , contoured surface  131  and bearings  63  mounted upon the shaft  55  preferably are configured to place substantially all of the applied compressive load upon the ball  53  and not the bearings  63 . When the plunger  41  is pulled downward by the activated solenoid  35 , the load previously applied by the plunger  41  to the wheelset  59  at the end of the arcuate lever  57  is released and gravity pulls the arcuate lever  57  into clockwise rotation about the pivot pin  61 , thus substantially releasing the compressive loads that lock into the place the pan-rotate interface  13  and allowing panning and rotation of the shaft  55 . The pan-rotate interface  13  includes a ball  53  and shaft  55  construct (collectively indicated with ref no. as  51 ), that, in one embodiment, is configured to provide a 15:1 leverage ratio for loads applied by the plunger  41  at a wheel set  59  housed in the extension member  11  and coupled to the proximal end of the arcuate lever  57 . 
     Referring to  FIG. 3.7 , the ball/shaft interface  51  comprises bearings  63  to facilitate stable panning rotation, as well as rotation of an associated structure about the longitudinal axis of the shaft  55 . The ball  53  preferably is greased to facilitate smooth panning and rotation when not compressibly locked into position. The bearings facilitate lateral panning of the shaft member  55  about a plane formed by the pan-rotate interface  13 , which causes the bearings  63  to rotate on a planar annulus about the center of the ball  53 . The result is constrained motion in two different degrees of freedom: lateral panning as per the planar annulus and bearing interface, and rotation about the axis of the shaft  55 . The bias force of the springs  43  on the plunger  41  extending from the solenoid housing  103  normally lock the ball/shaft interface  51  into place, preventing either panning or rotation motion at the interface. Electronic activation of the solenoid withdraws the pull-rod and, by extension, piston  41  away from the wheel set  59 , thereby unloading the significant compressive forces that otherwise keep the ball  53  locked into place, allowing for panning/rotation. 
     Referring also back to  FIG. 3.2 , the shaft  55  protrudes through a horizontal slot  111  located in a distal face  123  of the housing  121  covering the pan interface  13 . The slot  111  constrains the horizontal panning motion of the shaft  55  (and, by extension, the support member  15 ) in a plane that may be substantially parallel to the operating table within the range of motion defined by the boundaries of the slot  111 . 
     Referring to  FIG. 3.8 , the shaft  55  is coupled to a proximal sprocket  75  of the horizontal extension member  15  using a conventional interference fit, such as a “number 3 Morse taper.” The proximal sprocket  75  is coupled to a distal sprocket  74  by a timing chain  73 , so that rotation of the shaft  55  correspondingly rotates both sprockets  74  and  75 , preferably with a 1:1 ratio of rotational movement, resulting in the same rotational displacement at each of the sprockets. Rotational movement of the proximal sprocket  75 , caused by fixing the relative rotational position of the proximal sprocket  75  relative to the distal face  123  of the pan rotate interface  13  housing  121  with a key member  105  fitted into key slots ( 77 ,  109 ) defined by the distal sprocket  75  and pan rotate interface  13  housing  121 , causes rotation of a pin  65 , which in turn causes tension via a linkage  67 , proximal linkage base  71 , and distal linkage base  69 , respectively, to a set of gas tension springs  79  configured to constrain the rotational motion of the sprockets  74  and  75  (and, thus, of the shaft  55 ). The position ( 107 ) of the key member  105  is depicted in  FIG. 3.2 . Given this configuration, with the solenoid  35  activated and the pan rotate interface  13  free to move, the timing chain  73  and sprocket  74 / 75  configuration within the horizontal extension member  15  is configured to maintain the relative planar positioning of the most distal hardware of the system relative to the plane of the operating table. This is important because a robotic catheter driver (not shown; see  FIGS. 3.10A  and  3 . 10 B, for example) may be mounted upon the instrument driver interface  21  and pulled around by the handle  23 , with the solenoid activated and the brakes released, to rotate about the rotational axis  125  of the distal brake unit  19 , to rotate about the axis  119  of the rotatable frame member  45  within the solenoid and brake unit housing  3 , to rotate and pan about the pan-rotate interface  13  via connectivity of the horizontal extension member  15 , all simultaneously, without substantially changing the planar orientation of the instrument driver interface  21  relative to the plane of the operating table (not shown). In other words, the axis of rotation  125  of the proximal extension  127  of the instrument driver support shaft  17  may be configured to always be oriented perpendicular to the plane of the operating table, by virtue of the timing chain and sprocket interfacing of the extension member  15 . When electronically activated, the brake  19  allows rotational movement of the of the support shaft  17  about an axis of the proximal extension  127 . When the brake is not electronically activated, such rotational movement of the support shaft  17  is prevented. 
     Referring to  FIGS. 3.9A  and  3 . 9 B, the instrument driver support shaft  17  comprises an instrument driver mounting interface  21 , and a biasing spring  80  configured to at least partially counterbalance the cantilevered load upon the instrument driver interface  21  caused by the weight of an instrument driver mounted upon it. The biasing spring  80  preferably is covered by a spring housing  85 . A lead screw  81  is provided and configured to change the pitch of the instrument driver interface  21  relative to the support shaft  17  when a knob  83  is rotated. 
     Referring to  FIGS. 3.10A  and  3 . 10 B, an instrument driver fitted with a cover  129  is depicted mounted to the instrument driver interface  21 . The cover  129  is configured to provide an additional barrier between the instrument driver which is covers and draping, liquids, vapors, and other substances that may be encountered during a procedure. Preferably the cover  129  comprises a polymer or metal material and is made with processes such as stereolithography, injection molding, or machining. Preferably the cover  129  may be snapped or fastened into place around the instrument driver with simple recessed screws, bolts, or other fasteners. Similar covers may be configured to cover instrument bases. As depicted in  FIGS. 3.10A  and  3 . 10 B, the cantilevered mass of the covered instrument driver  129  creates a moment. Torsional loads associated with such moment are counteracted by the spring (not shown in  FIGS. 3.10A  and  3 . 10 B—see  FIG. 3.9A  ( 80 )) housed within the housing  85 . This counteraction is configured to prevent binding of the knob  83  actuated lead screw  81  pitch control of the instrument driver interface  21 . 
     In summary, a support assembly  26 , or support structure, is configured to allow for easy repositioning of an instrument driver or other device relative to an operating table when an actuation button is depressed, thereby activating a solenoid and releasing two electronic brakes. The position of an instrument driver then may be easily fine-tuned, for example, or modified quickly and substantially to remove the instrument driver from the immediate area of a patient on an operating table for quick medical intervention with broad physical access. Constraints limit the movement of the instrument driver relative to the operating table—i.e., a pan-rotate interface  13 , a horizontal extension member  15  with a rotational position maintaining timing chain  73  for distally-coupled structures, and brake-lockable rotations about two axes of rotation ( 125 ,  119 ) which may be parallel and both perpendicular relative to the plane of the operating table—to provide desirable mechanics. When an actuation button is not depressed and the structures are substantially locked into position relative to each other, with the exception of manually-activated lead screw pitch adjustment of an instrument driver interface  21 , the support assembly  26  is configured to provide a robust structural platform upon which an instrument driver or other device may be positioned relative to an operating table. 
     While multiple embodiments and variations of the many aspects of the invention have been disclosed and described herein, such disclosure is provided for purposes of illustration only.