Abstract:
A device for establishing an access channel to a target location is presented. The device includes a plurality of cylindrical segments. A plurality of backbones each extends through a backbone channel of each segment to join the plurality of segments together. When joined together, the central bore of each of the plurality of cylindrical segments align to form an access channel. A distal segment is fixedly attached to each of the plurality of backbones such that an orientation of the distal segment can be adjusted by linear movement of one or more of the plurality of backbones through the plurality of cylindrical segments. Furthermore, when linear movement of the plurality of backbones is restricted, the shape of the access channel can be adjusted by external forces while maintaining the orientation of the distal segment.

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/636,506, filed on Apr. 20, 2012 and titled “APPARATUS AND METHODS FOR QUICK AND SAFE DEEP ACCESS INTO MAMMALIAN ANATOMY,” the entire contents of which are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under grant IIS-1063750 awarded by the National Science Foundation. The government has certain rights in the invention. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to devices and methods for manipulating continuum segment robots. More specifically, the present invention relates to devices and methods for bracing continuum segment robots having an access channel therewith with respect to surrounding anatomy. 
     BACKGROUND OF THE INVENTION 
     Natural orifice transluminal endoscopic surgery (NOTES) is preferred over traditional open body surgery because the latter leaves scars, is prone to causing infection of access incision sites, and use of access incisions is associated with increased risk for hernia and formation of adhesions. In addition, natural orifice surgery is an improvement over minimally invasive surgery (MIS), which uses 3-5 access incisions with each incision associated with a scar, risk for infection, and risk for hernia. In natural orifice surgery, the operating site is reached via a natural opening. Also, in single port access surgery (SPAS) a single small incision is used to provide access to the anatomy. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention provides a medical robot that includes a flexible, steerable, and selectively lockable channel. The medical robot is remotely actuated to enable the robot to move into an anatomical cavity and is then locked into place once the distal end of the robot reaches a desired location. The channel serves as a stable passageway through which users (i.e., surgeons) can deploy and guide other surgical tools or medical robots. The flexible, steerable channel increases the operating range for the surgeon and prevents damage to healthy tissue during a procedure. The walls of the device surrounding the channel have a minimal outer to inner diameter ratio to achieve a desired bore clearance. 
     Various constructions reduce mechanical complexity by providing a passively compliant and actively locking channel for deep access. Constructions are also able to increase the available channel bore for a device with a given external diameter by eliminating internal and external locking channels that would be required for devices with more extensive wire-actuation systems. Some embodiments of the invention use flexible NiTi backbones and acts as a continuum robot when it is in a passively compliant mode. As such, the robot maintains the orientation of its tip (i.e., the distal end of the channel) despite change in the shape of its body. In some embodiments, the orientation of the robot tip is steerable using a joystick and vision feedback. Additionally, because the robot acts as a continuum robot, it is compatible with other devices and methods developed for robot manipulation (e.g., devices and methods for force sensing and contact detection). 
     Some embodiments of the invention provide a support platform for deployment of flexible endoscopes and robots through the central channel. In some embodiments, the device can be used to provide safe access for deployable trocars, laryngoscopes (i.e., for laryngeal surgery), trans-oral (i.e., endoscopic gastric surgery), trans-esophageal procedures (i.e., for treating Barrett&#39;s disease), trans-nasal (i.e., surgery of the upper airways), and trans-anal/trans-vaginal stabilization platforms. 
     Additionally, some embodiments or this device are used in conjunction with an automatic steering system to appropriately guide the tip. In some embodiments, the steering system includes a forward looking vision module having optic flow vision methods. In some embodiments, the steering system also includes contact and load sensors mounted in a circumferential array about the tip. Additional joint level force information is used by the steering system to initiate compliant motion control. 
     In one embodiment, the invention provides a device for establishing an access channel to a target location. The device includes a plurality of cylindrical segments. Each segment includes a first end, a second end, a central bore, and a plurality of backbone channels. The first end of each cylindrical segment is convex-shaped relative to the second end. A plurality of backbones each extends through one of the backbone channels of each segment to join the plurality of segments together. The first end of one cylindrical segment is at least partially received by the second end of a second cylindrical segment. When joined together, the central bore of each of the plurality of cylindrical segments align to form an access channel. A distal segment is fixedly attached to each of the plurality of backbones such that an orientation of the distal segment can be adjusted by linear movement of one or more of the plurality of backbones through the plurality of cylindrical segments. Furthermore, when linear movement of the plurality of backbones is restricted, the shape of the access channel can be adjusted by external forces while maintaining the orientation of the distal segment. 
     In some embodiments, the device further includes a brace mechanism that extends radially from the access channel and contacts an interior wall of a structure to anchor the access channel relative to the structure. In some embodiments, the device further includes a locking mechanism to restrict angular movement of the cylindrical segments relative to each other. In some embodiments, the locking mechanism includes a rotatable shaft with a plurality of teeth on a first side and a smooth surface on a second side. The rotatable shaft is positioned through a shaft channel in each of the cylindrical segments. Each cylindrical segment includes a locking tab biased towards the center of the shaft channel such that the locking tab engages the rotatable shaft when the teeth are positioned proximate to the locking tab and disengages the rotatable shaft is rotated such that the smooth surface of the rotatable shaft is positioned proximate to the locking tab. 
     In another embodiment, the invention provides a method for establishing an access channel to a target location in an anatomical structure. A passively flexible device is inserted into an orifice of a patient and a distal end of the passively flexible device is positioned at a target location inside the anatomy. The passively flexible device is then braced to anatomical features at the target location to lock the passively flexible device and to define the shape of the access channel to the target location. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 a -1 d    illustrate a device defining an access channel and including a backbone and a plurality of interconnected segments according to one embodiment of the present invention. 
         FIGS. 2 a -2 c    illustrate the device of  FIGS. 1 a -1 d    including a tip that maintains a constant orientation. 
         FIG. 3  illustrates the device of  FIGS. 1 a -1 d    including a first example of a brace mechanism. 
         FIG. 4  illustrates the device of  FIGS. 1 a -1 d    including a second example of a brace mechanism. 
         FIG. 5  illustrates the device of  FIGS. 1 a -1 d    including a locking mechanism. 
         FIG. 6  illustrates an enlarged view of a portion of the locking mechanism of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. 
     Although directional references, such as upper, lower, downward, upward, rearward, bottom, front, rear, etc., may be made herein in describing the drawings, these references are made relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form. In addition, terms such as “first,” “second,” and “third” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance. 
       FIGS. 1 a -1 d    illustrate a device  100  (i.e., a robot) that provides deep access into an anatomical cavity. The device  100  is both actively steerable and passively compliant. The robot  100  includes a plurality of backbones or wires  101  for positioning and manipulating the robot  100 . The backbones/wires  101  pass through a plurality of interconnected or interlinked segments  103 . In one construction, the backbones  101  are constructed of super-elastic NiTi (nickel titanium). Each of the segments  103  includes a wall defining a central bore or channel  105 . The wall includes a thickness of material, an inner surface, and an outer surface. Each of the segments also includes a first end  107  and a second end  109 . The first end  107  is convex-shaped relative to the second end  109 . Consecutive segments  103  are coupled or linked together such that the second end  109  of one segment at least partially receives the first end  107  of an adjacent segment. The wall includes a recess  111  formed therein at the first end (i.e., near the convex-shaped end). In other constructions, the recess can be positioned in other locations on the wall including shapes other than that illustrated in  FIGS. 1 a -1 d   . The recess  111  allows for stress relief of the superelastic NiTi wires  101 . The construction of the robot  100  illustrated in  FIGS. 1 a -1 d    is manipulated by three backbones (i.e., three recesses  111  and three channels that each correspond to one of three wires  101 ). In other constructions, the robot  100  could include additional backbones and, therefore, additional recesses and channels formed in the wall of each segment. 
     A distal segment forms the tip of the robot  113  while the proximal segment is rigidly attached to an external mount  115 . The super-elastic backbones  101  pass through channels formed with the wall of each segment  103  and attach at the distal tip  113  of the distal segment. The rigidity of the tip  113 , which is sustained by frictional moments between the consecutive segments, maintains the shape of the channel  105  when the device  100  is locked by pulling on the backbones  101 . When the channel  105  is in a relaxed state the backbones  101  are incrementally released such that frictional forces between subsequent segments are small and the shape of the access channel  105  may be changed by external forces or constraints from the anatomy. 
     As illustrated in  FIGS. 2 a -2 c   , when in a relaxed state, changes in the shape of the access channel  105  cause a corresponding change in the position of the tip  113 . However, the orientation of the tip  113  remains constant in space. This design acts as a generalized Shoenflies motion generator in a manner similar to the way parallelogram mechanisms are used to keep the orientation of a lamp fixed in space despite movement of the desk lamp. 
     Once the distal tip  113  of the device illustrated in  FIGS. 1 a -1 d    is positioned at a target location, the channel  105  provides a mechanism for safe and reliable access to the target location. Various tool including, for example, endoscopes can be inserted through the channel  105 . To further stabilizes the device, in some constructions, the segments that form the channel  105  are locked into place and braced against the surrounding anatomy.  FIGS. 3 and 4  illustrate two examples of mechanisms for providing circumferential bracing of the device. The robots illustrated in  FIGS. 3 and 4  are modifications of the robot illustrated in  FIGS. 1 a -1 d   . Therefore, the illustrations and discussion below focus on the modifications. 
     Like the example of  FIGS. 1 a -1 d   , the robot  300  illustrated in  FIG. 3  includes a plurality of backbones or wires that pass through interconnected or interlinked segments. The backbones/wires control the position and orientation of the distal tip of the robot. In this example, the backbones are comprised of one or more Kevlar strands or stainless steel wire rope with low bending resistance. Some or all of the segments include one or more additional channels or grooves formed within the wall. The additional channels can be formed entirely within the wall or can be formed as grooves along the inner surface of the wall exposed to the channel bore. In some embodiments, the additional channel is partially formed within the wall and partially exposed to the bore. Each additional channel/groove includes an aperture in communication with the recess for guiding super-elastic NiTi wires or other components of a bracing mechanism through a segment of the device. 
     In the example of  FIG. 3 , the bracing mechanism includes a series of six NiTi wires running through the interior channel of the device  300 . A first segment  301  includes a pair of channels oriented opposite one another on the inner surface of the segment  301 . The first pair of NiTi wires  303  are positioned in the channels of the first segment  301 . A support pad  305  is attached to the distal end of each NiTi wire  303 . Similar pairs of channels are formed in a second segment  307  for receiving a second pair of NiTi wires  309  and in a third segment  311  for receiving a third pair of NiTi wires  313 . Bracing of the device is achieved by pushing the pre-shaped NiTi wires through the channels of each segment such that they extend radially. This extension of the NiTi wires moves each support pad  305  into contact with the surrounding anatomy  315 . 
     The pre-shaped NiTi wires in  FIG. 3  may be pushed with an equal force for each wire by using external pistons connected to a hydraulic/pneumatic source with a common pressure used to actuate all pistons. Alternatively, the pre-shaped NiTi wires in  FIG. 3  may be pushed with an equal force for each wire by externally pushing them through linear actuators connected to constant force springs connected in series with the NiTi wires supporting the bracing pads. 
     The robot  400  illustrated in  FIG. 4  is similar to the robot in  FIG. 3 . However, the additional access channels used in  FIG. 3  for moving the support pads  305  into contact with the surrounding anatomy are used in  FIG. 4  to provide access to pneumatic pressure channels. The pneumatic pressure channels inflate circumferential balloons  401  for bracing the channel against anatomy. 
     In operation, the robot in  FIG. 4  is guided within a conduit or pathway of the anatomy  403 . The conduit or pathway of the anatomy may be tubular in shape or have irregular boundaries, irregular diameters along its length, or irregularly shaped and sized circumferences along its length. Once the robot is appropriately positioned, the pneumatic pressure source forces the balloons through the recesses in the first end of the segments such that the balloons are circumferentially inflated and anchor to the surrounding anatomy  403 . The balloons  401  brace the device  400  against the surrounding anatomy  403  by expanding to fill excess space therebetween. The braced device provides a safe and reliable channel for positioning medical tools (e.g., snake-like robots and endoscopes) to a target location. The braced device also enhances the ability to manipulate devices by supporting the distal end of the devices thereby increasing precision during a procedure. 
       FIG. 5  illustrates a locking mechanism of the device of  FIGS. 1 a -1 d    in further detail. The locking mechanism stiffens the otherwise flexible channel thereby increasing the channels rigidity once it has been appropriately positioned within the anatomy. The inner surface of the walls of each segment includes one or more additional channels for receiving a rotatable lock shaft  501  and at least one biased lock tab  503  for each channel. Although  FIG. 5  illustrates only a single additional channel for in each segment for receiving one rotatable lock shaft  501 , some constructions will include additional rotatable lock shafts positioned around the circumference of each segment to provide for increased rigidity of the device when locked. 
     Each lock shaft  501  is constructed of a flexible material such that its position and shape can change with the movement of the channel tube of the robotic device. As further illustrated in  FIG. 6 , the rotatable lock shaft  501  includes a plurality of teeth  601  formed on a single side of the rotatable lock shaft. The opposite side of the lock shaft  501  is smooth. The rotatable lock shaft is formed of a plurality of segments including a first lock shaft segment  603  and a segment lock shaft segment  605 . 
       FIG. 5  illustrates the device with the locking mechanism engaged. Once the robot is appropriately positioned, the lock shaft  501  is rotated such that the teeth  601  engage the lock tab  503  in each segment. As further illustrated in the cross-sectional insert of  FIG. 5 , each lock tab  503  is biased by a spring  505  such that it engages the teeth  601  of the lock shaft  501 . With the lock tabs  503  engaged with the teeth  601  of the lock shaft  501  lateral movement of the individual segments relative to the lock shaft  501  is prevented. As such, angular movement of each segment relative to the other segments is also prevented. To disengage the locking mechanism, the lock shaft  501  is rotated such that the smooth side of the lock shaft  501  contacts the lock tabs  503 . The lock tabs  503  do not engage the smooth surface of the lock shaft  501  and, as such, angular movement of the individual segments is not restricted by the lock shaft  501 . 
     The lock shaft  501  illustrated in  FIGS. 5 and 6  includes a first segment  603  and a second segment  605 . In some constructions, the segments are independently rotatable such that portions of the device can be locked independently of the device as a whole. In other constructions, the lock shaft  501  may contain even more independent segments. Furthermore, although the example of  FIG. 6  illustrates the teeth  601  all arranged on the same side of the lock shaft  501 , in still other constructions, the teeth  601  can be arranged on different surfaces to implement more advanced locking configurations such as, for example, phase shifting. 
     Each of the constructions described above provides a device for establishing a safe, quick, and reliable access channel to a target location. As described above, the device includes a passively flexible robot with a controllable distal tip. In some constructions, the device is designed to operate with an auxiliary continuum robot system that is inserted through the access channel once the primary robot is properly placed and locked/braced within the anatomy. When used together, the primary robot described above enables quick deployment of the auxiliary robot to a target location and enables real-time feedback about patient outcome as it may be implemented with a highly localized anesthetic. When used together, the two robot systems are able to provide online feedback via optical coherence tomography and ultrasound probes. Further, constructions that include force-sensing capabilities are able to palpate tissue by actively moving the joint and measuring forces of constraint to discern various conditions such as arytenoids joint constraint. The result of discerning these conditions is that intra-surgical treatment plans can be designed and carried out. The two robotic systems are capable of being used in more precise deployment of chemotherapy to the lungs as well. 
     It should be noted that while each of the embodiments discussed herein are implemented automatically by robotic technology. However, each of the embodiments could be manually operated as well. Furthermore, although the technologies are described above in the context of minimally invasive or NOTES procedures within anatomical structures, other constructions may be used in non-surgical settings where a safe and reliable access channel to a target site within an orifice is desired. 
     Thus, the invention provides, among other things, a device and method for securing a flexible channel within the anatomy thereby providing a pathway that protects surrounding tissue by guiding additional tools and devices. Various features and advantages of the invention are set forth in the following claims.