Abstract:
Propellable apparatus, assemblies and related methods including a self-enclosed member are disclosed. The self-enclosed member can include an inner surface at least partially defining an enclosed region, and an outer surface that turns outwardly to engage a cavity or lumen wall in addition to turning inward to at least partially encompass a central region defining a longitudinal path. The apparatus can include an internal drive mechanism engageable with the outer surface of the self-enclosed member to provide relative movement between the self-enclosed member and the cavity or lumen wall. A tapered member, positioned on the apparatus adjacent an end of the self-enclosed member, can provide a size transition between an outer surface portion of the self-enclosed member and an outer surface of a payload insertable within the central region. In some examples, one or more reinforcing members can be integrated within the self-enclosed member for increased durability and rotational use.

Description:
CLAIM OF PRIORITY 
     This non-provisional application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/152,780 filed on Feb. 16, 2009, entitled “PROPELLABLE APPARATUS AND RELATED METHODS,” the specification of which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This patent document pertains generally to an apparatus configured to facilitate carrying a payload. More particularly, but not by way of limitation, this patent document pertains to a propellable apparatus configured to facilitate carrying a payload, such as an endoscope or other instrument, into a body or non-body cavity or lumen. 
     BACKGROUND 
     An endo scope is an instrument often used in medical procedures to view a location of interest within a subject&#39;s body and transmit such view(s) to a caregiver or other observer. Endo scopes can also be used to perform a variety of diagnostic and interventional procedures, such as biopsies and other small surgical procedures. Examples of endo scopes include a colono scope configured for use within the colon, an entero scope configured for use within the stomach or small bowel, and a bronchoscope configured for use within the trachea or bronchi. Endo scopes are typically inserted into body cavities or lumens via a natural bodily orifice, but can also be inserted via a surface incision to gain access to the internal location of interest. 
     OVERVIEW 
     One approach in facilitating advancement of an endo scope or other similar payload instrument into, within, and out of a cavity or lumen includes using a propellable apparatus, such as described in Ziegler et al. U.S. Pat. No. 6,971,990, entitled “PROPULSION MECHANISM FOR ENDOSCOPIC SYSTEMS;” Ziegler et al. U.S. Patent Application Publication No. 2006/0089533, entitled “SELF-PROPELLABLE APPARATUS AND METHOD;” Ziegler et al. U.S. Patent Application Publication No. 2008/0045790, entitled “SELF-PROPELLABLE ENDOSCOPIC APPARATUS AND METHOD;” Sheridan U.S. Patent Application Publication No. 2009/0233747, entitled “TORQUE-ADJUSTING DRIVE MECHANISM FOR A DEVICE;” Allen et al. U.S. Patent Application Publication No. 2009/0227838, entitled “PROPELLABLE APPARATUS WITH PASSIVE SIZE CHANGING ABILITY;” and Eidenschink et al. U.S. Patent Application No. 61/243,208, entitled “PROPELLABLE APPARATUS WITH ACTIVE SIZE CHANGING ABILITY,” the disclosures of each of which are herein incorporated by reference in their entirety, including their descriptions of a propellable apparatus and related methods. 
     In various examples, a drive structure including one or more drive members and gear or wheel power couplings can be mounted on the endoscope or other payload instrument. The drive structure can propel a self-enclosed member (e.g., self-enclosed tube, such as a toroidial membrane, or self-enclosed strips) to create propulsion force against a cavity or lumen wall. This propulsion force can aid in advancing or withdrawing the endoscope or other payload instrument relative to a cavity or lumen wall. 
     In some examples, the propellable apparatus comprises a permeable self-enclosed member; while in other examples, the propellable apparatus comprises an impermeable self-enclosed member. The self-enclosed member can be sized and shaped to fit within and engage a cavity or lumen wall. The self-enclosed member can comprise an inner surface defining an enclosed region, and an outer surface that turns outward to engage the cavity or lumen wall in addition to turning inward to encompass a central region defining a concentric longitudinal path. An attachment can be coupled to the self-enclosed member. The attachment can be configured to secure engagement between an endoscope or other payload instrument and the self-enclosed member. The self-enclosed member can be powered to provide movement relative to the cavity or lumen wall. This can help move the payload, with respect to the cavity or lumen, in at least one of a forward or reverse direction with respect to the defined longitudinal path. 
     Various options for the above-referenced propellable apparatus are available, each of which can be beneficial in certain applications and circumstances. In some examples, the attachment between the propellable apparatus and the payload is made at a front-end tip portion of the payload. This can be advantageous for advancing the payload through sharp bends in a body cavity or lumen. In some examples, the propellable apparatus can be made to have a relatively short length (e.g., between about 0.8 inches and about 1.5 inches) so-as-to not limit the articulation of a payload, having a separately controllable articulating capability, when it is mounted at or near the front-end thereof. In some examples, the one or more drive members can be made of flexible cables including wrapped filaments instead of solid wire to allow greater flexing of the drive members without reaching unacceptable internal stress levels. In some examples, an additional component such as a wiper can be added to at least one end of the propellable apparatus, thereby shielding tissue from the apparatus drive mechanism. In some examples, a tapered member (e.g., a wedge-shaped member) can be added behind the propellable apparatus to provide a size transition from the outer surface of the payload to the larger diameter, outer surface of the self-enclosed member (e.g., tube), thereby easing withdrawn of the apparatus from the cavity or lumen. The tapered member can be passively or actively (e.g., actuatably) expanded and contracted, as needed or as desired. In some examples, different reinforcing members may be used for the rotating, self-enclosed member to improve its durability and rotational use. 
     To better illustrate the present propellable apparatus, a non-limiting list of examples is provided here: 
     In Example 1, a propellable apparatus comprises a self-enclosed member configured to fit within and partially engage a cavity or lumen wall, the self-enclosed member including an inner surface at least partially defining an enclosed region, and an outer surface that turns outwardly to engage the cavity or lumen wall in addition to turning inward to at least partially encompass a central region defining a longitudinal path; an internal drive mechanism engageable with the outer surface of the self-enclosed member, thereby providing relative movement between the self-enclosed member and the cavity or lumen wall; and a tapered member positioned adjacent an end of the self-enclosed member, the tapered member providing a size transition from the end of the self-enclosed member to a diametrically smaller, outer surface of a payload insertable within the central region. 
     In Example 2, the propellable apparatus of Example 1 is optionally configured such that the tapered member is actively expandable or contractible. 
     In Example 3, the propellable apparatus of Example 2 is optionally configured such that the tapered member comprises a conically-shaped, actively inflatable balloon. 
     In Example 4, the propellable apparatus of Example 3 optionally comprises one or more tubular members configured to move a fluid into or out of the inflatable balloon for size adjustment use. 
     In Example 5, the propellable apparatus of any one or any combination of Examples 1-4 is optionally configured such that the inflatable balloon includes at least one groove configured to house one or more elongate or tubular members (e.g., elongate drive members engagable with the internal drive mechanism or tubular members configured to move the fluid into or out of the inflatable balloon). 
     In Example 6, the propellable apparatus of any one or any combination of Examples 1-5 is optionally configured such that the tapered member includes a wedge-like cross-sectional shape when viewed in a longitudinal direction. 
     In Example 7, the propellable apparatus of any one or any combination of Examples 1-6 is optionally configured such that the tapered member is coupled adjacent a back-end of the self-enclosed member. 
     In Example 8, the propellable apparatus of any one or any combination of Examples 1-7 optionally comprises one or more wiper members including an edge configured to press against the outer surface of the self-enclosed member, thereby removing debris as the self-enclosed member turns inward. 
     In Example 9, the propellable apparatus of Example 8 is optionally configured such that the edge of the one or more wiper members includes a lubricious coating. 
     In Example 10, the propellable apparatus of any one or any combination of Examples 1-9 optionally comprises an attachment coupled in proximity to the self-enclosed member, the attachment configured to couple the payload within the central region. 
     In Example 11, the propellable apparatus of Example 10 is optionally configured such that the payload longitudinally extends from a handle portion to a leading viewing portion, and wherein the self-enclosed member is attached at the leading viewing portion. 
     In Example 12, the propellable apparatus of any one or any combination of Examples 10 or 11 is optionally configured such that the payload is an endo scope. 
     In Example 13, the propellable apparatus of any one or any combination of Examples 1-12 optionally comprises one or more drive members configured to transmit externally-generated power to the internal drive mechanism, and wherein the one or more drive members include a plurality of filaments wound in at least a first direction and a second direction, the second direction different than the first direction. 
     In Example 14, the propellable apparatus of any one or any combination of Examples 1-13 is optionally configured such that the internal drive mechanism is configured to receive power in a first form and convert the first form power to a linear impelling power received by the self-enclosed member. 
     In Example 15, the propellable apparatus of Example 14 is optionally configured such that the internal drive mechanism includes a worm gear located at least partially within the central region, the worm gear, when powered, configured to impart the linear impelling power to the self-enclosed member via a motive drive wheel or gear. 
     In Example 16, the propellable apparatus of Example 15 is optionally configured such that the worm gear is coupled to a mechanical power transmission providing a spinning mechanical power, the worm gear configured to partially convert the spinning mechanical power to the linear impelling power. 
     In Example 17, the propellable apparatus of any one or any combination of Examples 1-16 is optionally configured such that a longitudinal length of the apparatus is less than about 1.5 inches, less than about 1.4 inches, less than about 1.3 inches, less than about 1.2 inches, less than about 1.1 inches, or less than about 1.0 inches, such that the apparatus length is less than a length of a payload&#39;s rigid front-end tip portion. 
     In Example 18, a propellable apparatus comprises a self-enclosed member sized and shaped to fit within and engage a cavity or lumen wall, the self-enclosed member including an inner surface at least partially defining an enclosed region, and an outer surface that turns outwardly to engage the cavity or lumen wall in addition to turning inward to at least partially encompass a central region defining a longitudinal path; and at least one reinforcing member embedded between the inner surface and the outer surface of the self-enclosed member. 
     In Example 19, the propellable apparatus of Example 18 is optionally configured such that the at least one reinforcing member includes a stiffness or a toughness greater than a stiffness or toughness of the self-enclosed member. The reinforcing member can have a reduced axial elasticity as compared to the surrounding material of the self-enclosed member. Optionally, the reinforcing member can include a mesh configuration to yield relative inelasticity in a direction of rotation with relatively high flexibility in bending. 
     In Example 20, the propellable apparatus of any one or any combination of Examples 18 or 19 optionally comprises an internal drive mechanism engageable with the outer surface of the self-enclosed member, thereby providing relative movement between the self-enclosed member and the cavity or lumen wall. 
     In Example 21, the propellable apparatus of Example 20 is optionally configured such that the internal drive mechanism includes one or more gears or wheels, and wherein the at least one reinforcing member is positioned in line with a position of the one or more gears or wheels. 
     In Example 22, the propellable apparatus of Example 21 is optionally configured such that the outer surface of the self-enclosed member includes one or more tread sections configured to engage with the one or more gears or wheels of the internal drive mechanism. 
     In Example 23, the propellable apparatus of any one or any combination of Examples 18-22 is optionally configured such that the at least one reinforcing member includes at least one of a peek, a nylon, a polyester or a urethane material. 
     In Example 24, the propellable apparatus of any one or any combination of Examples 18-23 is optionally configured such that the at least one reinforcing member is molded into the self-enclosed member. 
     In Example 25, a propellable apparatus comprises means for providing an inner surface and an outer surface which move in opposite directions when the apparatus is in motion, including providing a self-enclosed member defining a central cavity and having an enclosed region, which is configurable to enter into and navigate a cavity or lumen; means for providing a tapered size transition between a member disposable with the central region and an outer surface portion of the self-enclosed member; means for reinforcing a stiffness or toughness of the self-enclosed member; and means for propelling the self-enclosed member using the outer surface. 
     In Example 26, the propellable apparatus of Example 25 is optionally configured such that the means for reinforcing includes means for decreasing driving force transmission loss to the self-enclosed member, when powered. 
     In Example 27, the apparatus of any one or any combination of Examples 1-26 is optionally configured such that all elements or options recited are available to use or select from. 
     These and other examples, advantages, and features of the present propellable apparatus, assemblies and related methods will be set forth in part in following Detailed Description. This Overview is intended to provide an introduction to the subject matter of the present patent document. It is not intended to provide an exclusive or exhaustive explanation of the invention. The Detailed Description is included to provide further information about the present patent document. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like numerals can be used to describe similar components throughout the several views. Like numerals having different letter suffixes can be used to represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various propellable apparatus embodiments discussed in the present document. 
         FIG. 1  illustrates an example of a cross-sectional view of a propellable apparatus and a payload, as constructed in accordance with at least one assembly embodiment. 
         FIG. 2  illustrates an example of an attachment position between a propellable apparatus and a payload, as constructed in accordance with at least one assembly embodiment. 
         FIG. 3  illustrates an example of a cross-sectional view of a propellable apparatus, including a tapered-member, and a payload, as constructed in accordance with at least one assembly embodiment. 
         FIG. 4  illustrates an example of an isometric view of a wiper member positionable at an end of a propellable apparatus, as constructed in accordance with at least one embodiment. 
         FIG. 5  illustrates an example of a cross-sectional view of a propellable apparatus, including a back-end positioned wiper and tapered member, and a payload, as constructed in accordance with at least one assembly embodiment. 
         FIG. 6  illustrates an example of an isometric view of a propellable apparatus, including an actively expandable and contractible tapered member positioned at an apparatus back-end, associated drive members, and inflation/deflation tubes, as constructed in accordance with at least one embodiment. 
         FIG. 7  illustrates an example of a schematic view of a propellable apparatus, including a back-end positioned tapered member mounted via a wiper member, and a payload, as constructed in accordance with at least one assembly embodiment. 
         FIG. 8  illustrates an example of a cross-sectional view of a self-enclosed member, as constructed in accordance with at least one embodiment. 
         FIG. 9  illustrates an example of a cross-sectional view of a self-enclosed member including a reinforcing member, as constructed in accordance with at least one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present inventors have recognized, among other things, that a variety of challenges are faced in the area of endoscope advancement through body cavities or lumens. Traditional endoscopes, for example, include a rigid or semi-rigid rod or shaft, which can be inserted into a natural orifice or incision and forced through the associated body cavity or lumen to the location of interest. However, when a body cavity or lumen pathway is constricted, convoluted or consists of many curves, as can be the case with the colon, the stomach or small bowel, it can be difficult or impossible to forcibly push the endoscope to the desired location(s). In addition, the increased force required in traversing through each additional turn or corner of the cavity or lumen pathway raises the risk of subject surgical complications, such as bowel perforation and patient discomfort and pain experienced during or after a procedure. 
     The present inventors have also recognized that in a field different from medical applications, optical or other payload instruments can be used in non-medical commercial and industrial applications to obtain views, for example, from non-body cavity or lumens, such as sections of pipe or other structures having a number of curves and turns. Such non-body cavity or lumens can be partially occluded or have build-up on an inner surface and thus present an irregular internal shape or diameter impeding advancement of the viewing or other payload instruments. 
     One promising approach to endoscope or other payload instrument advancement through a body or non-body cavity or lumen can be a propellable apparatus configured to help advance the endoscope or other payload instrument through constricted, convoluted or curved pathways. To this end, the present inventors have recognized that (1) it can sometimes be advantageous to attach the propellable apparatus at a front-end tip portion of a payload, (2) a propellable apparatus having a relatively short length (e.g., between about 0.8 inches and about 1.5 inches) does not limit articulation of a flexible payload, having a separately controllable articulating capability, an appreciable degree when it is mounted at or near the front-end thereof, (3) drive members made of flexible cable including wrapped filaments allows for adequate flexing without reaching unacceptable internal stress levels during rotation, (4) one or more wiper members can be added to the propellable apparatus, such as at one or both apparatus ends, to prevent tissue from engaging with the apparatus drive mechanism, (5) a tapered member can be added to a back-end of the propellable apparatus to facilitate removal of the apparatus from a cavity or lumen, and (6) one or more reinforcing members can be integrated within a self-enclosed member for increased durability and rotational use. 
     As shown in  FIG. 1 , a propellable apparatus  100  can comprise a self-enclosed member  102  (e.g., self-enclosed tube, such as a toroidial membrane, or self-enclosed strips), which is sized and shaped to fit within and engage a cavity or lumen wall and be attachable to a payload  104  (e.g., an endoscope or other instrument). Rotation of the self-enclosed member  102  can create a propulsive force against the cavity or lumen wall. In various examples, power to actuate the self-enclosed member can be generated outside the cavity or lumen and be transmitted to the self-enclosed member  102  via one or more elongate drive members  106 . At or near the self-enclosed member  102 , the elongate members  106  can engage with one or more internal drive mechanisms  108  (e.g., one or more worm gears or motive drive wheels), which in turn can be engaged with an outer surface  110  of the self-enclosed member  102  as it passes through its smaller internal diameter  112 . This allows the self-enclosed member  102  to engage the cavity or lumen wall as it travels through its larger diameter  114 . In various examples, one or more rollers or skids  116  can be used to bias portions of the self-enclosed member  102  against an alternating sequence of peaks separated by respective grooves of one or more gears or wheels of the internal drive mechanisms  108 . 
     In some examples, as shown in  FIG. 2 , it has been found advantageous to attach a propellable apparatus  100  at a front-end tip portion  202  of a payload  104 . Mounting the propellable apparatus  100  at the front-end tip portion  202  of the payload  104  can have advantages in some body anatomies for gathering lumen tissue, for example, over the tip of an endoscope and helping the endoscope tip navigate through sharp folds or narrowing diameters in a body cavity or lumen. 
     This mounting location can be advantageous in tortuous cavities or lumens, as compared to mounting the propellable apparatus  100  further back on the payload  104  behind an articulating section  204 . The reasoning behind this is that the tissue of the cavity or lumen wall will have some drag against the tip of the payload  104 , and this drag typically increases as the tip is flexed more for tortuous anatomy. If this drag over the tip is greater than the force with which the self-enclosed member  102  is acting to draw tissue over the propellable apparatus  100 , then the apparatus  100  may fail to gather tissue over the tip of the payload  104 . Conversely, if the propellable apparatus  100  is mounted at the front-end tip portion  202  of the payload  104 , there can be little to no drag in front of the apparatus  102  resisting the rotating, self-enclosed member&#39;s  102  effect on the gathering of wall tissue over the tip of the payload  104 . 
     Mounting the propellable apparatus  100  at the front-end tip portion  202  of the payload  104  can, however, put demands on the propellable apparatus  100 , which are not present if the apparatus  100  is mounted behind the payload&#39;s articulating, steerable section  204 . The ends of endoscopes, for example, have flexible steerable sections that a physician can deflect using controls on a handle of the endoscope. One challenge of mounting the propellable apparatus  100  on the front-end tip portion  202  of the payload  104  is to not inhibit the physician&#39;s ability to control the articulation of the payload tip. The articulating section  204  of a scope is typically about 3 inches long and is located immediately adjacent an about 1 inch rigid section  206  at the tip which houses the scope&#39;s optics. To not inhibit the articulation an appreciable degree, the propellable apparatus  100  can be mounted on the rigid section  206  at the front-end tip portion  202  and the propellable apparatus  100  length can be about 1 inch in length, in some examples, for scopes having these typical dimensions. In other examples, the propellable apparatus  100  length can be less than about 1.5 inches, less than about 1.4 inches, less than about 1.3 inches, less than about 1.2 inches, less than about 1.1 inches, or less than about 1.0 inches, such that the apparatus length is less than a length of a rigid section  206  located at or near a front-end tip  202  of a payload  104 . These lower limits can be advantageous for small bowel and other applications where relatively smaller and more articulatable payloads may be used. An example of a propellable apparatus  100  meeting this desired length is shown in the cross-sectional side view of  FIG. 3 . As compared to  FIG. 1 , it can be seen that the internal drive mechanisms  108  and opposing one or more rollers or skids  116  have been compressed in their spacing to yield a shorter overall apparatus  100  length. 
     A second aspect of mounting the propellable apparatus  100  at the front-end tip portion  202  of the payload  104  is that the articulating section  204  of the payload  104  is able to flex to a smaller radius of curvature  208  than the radius of curvature  210  of the body of the payload  104  behind the articulating region  204  (see,  FIG. 2 ). In some typical colonoscopes, the radius of curvature at maximum flexing is about 1 inch for the articulating section and about 2 inches for the body of the scope. This can have implications for the apparatus elongate drive members  106  if the propellable apparatus  100  is mounted at the front-end tip portion  202  of the payload  104 , as these drive members  106  may need to tolerate a smaller radius of curvature in use when the apparatus  100  is mounted at the front-end tip portion  202  of the payload  104  relative to being mounted behind the articulating section  204 . 
     Rotating drive members  106  are subjected to oscillating stresses when they are flexed during rotation. These oscillating stresses can result in fatigue failure of the drive members  106 , if the stresses are high enough. These stresses increase as the radius of curvature decreases for a given drive member  106  design. For this reason, it may be desirable to use drive members  106  that operate at lower oscillating stresses for a given radius of curvature when the propellable apparatus  100  is to be mounted at the front-end tip portion  202  of the payload  104 . 
     One possible way of reducing the stresses due to bending is to use one or more smaller diameter drive members  106 . The smaller diameter can decrease the stresses due to bending, however, the smaller diameter can also decrease the amount of torsional load the wire can carry. A second possible way to decrease the stresses in the drive members  106  due to bending can be to use a cable including wound filaments for each of the drive members  106  instead of a solid wire. Drive cables may be produced, for example, by winding small diameter filaments in a helical pattern around a central wire in a first direction, and further winding more small diameter filaments around the outside of the first helically wound filaments in a second, opposite direction. Additional small diameter filaments can further be wound over the opposite direction filaments, as needed or as desired. Having the helical filaments wound in more than one direction allows the resulting cable to transmit torque in both rotational directions without unacceptable unwinding of the wound filaments. Due to the smaller diameter of the individual filaments used, the drive members  106  can tolerate a smaller radius of curvature as compared to solid drive wires. This can allow use of a larger diameter cable than a solid drive wire for a given application. This can further provide greater flexibility in meeting both torsional and fatigue requirements for the one or more drive members  106 . 
     When mounting a propellable apparatus  100  at the front-end tip portion  202  of a payload  104 , a cable including small diameter filaments can be use for the entire length of the one or more drive members  106 . A cable including small diameter filaments can also be used in a composite drive member  106  construction with the cable including filaments used for the length along the articulating section  204  of the payload  104  and a solid drive wire behind the articulating section  204  where the bending radius requirements are decreased. A composite drive member construction can be desirable to minimize propellable apparatus manufacturing costs, as the cable construction is likely to be more expensive than the solid drive wire. One example of a solid wire drive wire for a propellable apparatus  100  application is a straightened 400 kpsi stainless steel 0.022 inch diameter wire. One example of a cable including filaments that can be used for a propellable apparatus  100  application is a 0.050 inch cable produced by SS White® Technologies, Inc. of Piscataway, N.J., which includes four wires wrapped around a central wire and two sets of six wires wound around the four wires in an opposite direction. All of these individual filaments, in this example, are 0.007 inches in diameter. 
     A third challenge of mounting the propellable apparatus  100  at the front-end tip portion  202  of the payload  104  is that heat can build up at the tip. Endoscopes, for example, can include small lights at their tips projecting forward to allow the physician to see down a cavity or lumen with the optics mounted at the tip. These lights generate heat and this heat should be dissipated. If the heat were to build up and the temperature of the tip became excessively high, it can possibly degrade the image quality of the optics. It could also become a risk of damaging cavity or lumen wall bodily tissue that contacts the heated end of the scope. 
     Mounting the propellable apparatus  100  over the front-end tip portion  202  of the payload  104  could help insulate the tip, limiting the heat dissipation to adjacent bodily tissue. Additionally, the one or more gear power couplings  108  and drive members  206  interface could generate additional heat of its own. Thus, in some embodiments, it may be desirable to control the heat generated by the internal drive mechanisms  108  of the propellable apparatus  100 . This can be done by, for example, minimizing the drive power input to the propellable apparatus  100  needed by minimizing the drag of the self-enclosed member  102  as it rotates. To this end, lubricious materials and coatings for the contact surfaces and the self-enclosed member  102  itself can be added. Heat reduction can also be addressed using a small amount of cooling water introduced inside the propellable apparatus  100 . In one example, the cooling water can be introduced through a tubular member in the one or more drive members  106  (see,  FIG. 3 ), which exits inside the propellable apparatus  100  in the internally-positioned drive mechanism  108  or in a lumen  302  between the propellable apparatus  100  and the payload surface. 
     In various examples, such as are shown in  FIGS. 1 ,  3 ,  4 ,  5  and  7 , the propellable apparatus  100  can include a wiper member  402 . The present inventors have found that, in practice, it should be assured that bodily tissue or other cavity or lumen debris is not pulled via the self-enclosed member  102  into the internally-positioned drive mechanisms  108  as the self-enclosed member  102  rotates into its small diameter path  112  (see,  FIG. 1 ). In  FIG. 1 , a wiper member  402  is shown mounted to a portion of the internal drive mechanism  108 , with an edge  404  pressing against the self-enclosed member  102  as it passes into its smaller diameter  112  path. In various examples, the wiper member  402  is a component that can be added to the propellable apparatus  100  assembly to prevent or inhibit tissue or other cavity or lumen debris from being pulled into the internal mechanisms of the apparatus  100  by the rotating, self-enclosed member  102 . The wiper member  402  can act like a squeegee to separate any tissue or other debris from sticking to an outer surface of the self-enclosed member  102 . One example of an isometric view of a wiper member  402  is shown in  FIG. 4 . 
     As shown in  FIG. 5 , the wiper member  402  can also be placed against the outer surface  110  of the self-enclosed member  102  at or near its larger outer diameter  114 . In various examples, the wiper member  402  can be rigid and shaped to substantially match the contour of the outer surface of the self-enclosed member  102 , or it can be flexible and conform to this outer surface. The wiper member  402  can be made of a wide range of engineering polymers or metals. In one example, the wiper member  402  is made from Santoprene®281 having a 55 MED durometer. In some examples, the wiper member  402  is made of a relatively lubricious polymer (e.g., fluoropolymers) to minimize the drag it adds to the rotation of the self-enclosed member  102 . In some examples, the wiper member  402  is coated with a lubricious material, such as silicone oil or a hydrophilic coating. 
     In various examples of the propellable apparatus  100 , such as the apparatus shown in  FIG. 1 , the back-end  502  includes a fairly abrupt diameter change  504  between the outer diameter  114  of the self-enclosed member  102  and a diameter of the payload  104  located behind it. In some examples, it can be desirable to have this diameter change  504  taper more gradually, such that there are few to no ledges to catch bodily tissue or other debris on as the propellable apparatus  100  is being withdrawn through a cavity or lumen. It may also be desirable to have the rigid length of the propellable apparatus  100  as short as possible to ease advancement through tortuous anatomy and to not inhibit payload  104  articulation when the propellable apparatus  100  is mounted on the front-end tip portion  202  of an articulating payload, such as an endoscope. 
     It may be further desirable to have a tapered member (e.g., a wedge-shaped member)  506  that does not hinder the effectiveness of any propellable apparatus  100  components, such as the various wiper members discussed above. In one example, as shown in  FIG. 6 , the tapered member  506  is in the form a conically-shaped, actively inflatable balloon  602 , which is sleeved over a portion of a payload  104  behind the propellable apparatus  100 . In this way, the balloon  602 , when inflated, creates a smooth tapered diameter transition from the back-end  502  of the rotating membrane to the surface of the payload  104 . This inflatable balloon  602  can be attached to the back-end  502  of the propellable apparatus  100  such that its position relative to the back-end  502  is fixed. In some examples, one or more tubular members  604  to inflate or deflate the balloon can be included in the casing of the one or more drive members  106  of the propellable apparatus  100 . In practice, this balloon  602  can be un-inflated and collapsed or otherwise contracted when the scope is being advanced forward in a cavity or lumen, assisted by the propellable apparatus  100  and its rotating, self-enclosed member. After reaching a target point in the cavity or lumen, such as the cecum during colonoscopy, the rotation of the self-enclosed member  102  can be stopped and the balloon can be  602  inflated. The payload  104  can then be withdrawn through the cavity or lumen as the operator (e.g., physician) does his/her inspection. It is believed that the presence of an activatable (e.g., actuatable) tapered member  506 , such as the balloon  602 , can minimize drag in the cavity or lumen when in a deflated state during advancement, and minimize risk of tissue or other debris hang up during withdrawal when in an expanded state. 
     Other options for the tapered member  506 , and particularly the balloon  602 , can be as follows. The balloon  602  can be made to be flexible so that it does not inhibit any desired flexing of the payload  104  beneath it. This could be valuable when the propellable apparatus  100  is mounted at the front-end tip portion  202  of the payload  104  and the balloon  602 , at least in part, is mounted over the payload&#39;s articulating section  204  (see,  FIG. 2 ). In one example, the balloon  602  is formed from sheet urethane having a durometer of about 80 A and a thickness of about 0.003 inches. The sheet urethane can be cut and heat sealed into a conical balloon shape having a diameter at one end approximately equal to the diameter of the rotating, self-enclosed member  102  of the propellable apparatus  100 . The balloon  602  can be sealed down at its base to a cylindrical urethane tube having a diameter slightly larger than the diameter of the payload  104  it is sliding or otherwise advancing over. A groove  606  can be formed in the conical or otherwise shaped balloon  602 , such as by heat sealing the balloon down to the urethane tube in one line along the length of the balloon  602 . This groove  606  can act as a path for the one or more drive members  106  powering the rotating propellable apparatus  100  or the one or more tubular members  604  used to inflate or deflate the balloon  602 . In some examples, the actual inflation and deflation of the balloon  602  can be done with a syringe and a stop cock on the end of the inflation tubular members  604  off the drive members  106 , at or near their connection  608  to a motor controller. 
     In another example, as shown in  FIG. 7 , the tapered member  506  is achieved with a flexible polymer component  702  fixedly mounted to the propellable apparatus  100 , such as via a wiper member  402 . In this example, the tapered member  506  is passive and does not require actuation on the part of the operator (e.g., physician). The tapered member  506  of  FIG. 5  shows a second variation of this approach. In some examples, as shown in  FIG. 7 , the tapered member  506  including a flexible polymer component  702  is connected behind the wiper member  402  and leaves clearance  704  off of the rotating, self-enclosed member  102  to minimize the risk of creating a tissue or other debris pinch point. In  FIG. 5 , the wiper member  402  is integrated into the tapered back piece  506  and has the wiper edge  404  on the outer surface of the rotating, self-enclosed member  102 . 
     In various examples, as shown in  FIGS. 8 and 9 , the propellable apparatus  100  includes a self-enclosed member  102  having one or more of a thicker walled section  804 , a tread  802 , or a reinforcing member  902 . In various examples, the self-enclosed member  102  can be configured to decrease transmission loss thereto of the driving forces provided by the internal drive mechanisms  108 . In some examples, at least a portion of the outer surface of the self-enclosed member  102  can include a tread  802  having an alternating sequence of peaks separated by respective grooves (e.g., teeth), which are configured to engage with the alternating peaks and grooves of one or more gears or wheels of the internal drive mechanisms  108  (see,  FIG. 1 ). As shown in  FIG. 1 , these gears or wheels may be engaged against the tread by biasing rollers or skids  116  positioned inside the self-enclosed member  102 . 
     In use, the gears of the drive mechanisms  108  may skip or slip over the treads in the surface of the self-enclosed member  102  if enough rotational drag is placed on the member  102 . This skipping or slipping can also occur if the self-enclosed member  102  has a smooth surface (e.g., without a tread). In addition, the skipping or slipping can get worse if the self-enclosed member  102  is relatively more elastic and can stretch as a result of increased rotational drag on the member  102 . Minimizing the skipping or slipping of the self-enclosed member  102  over the gears can be desirable both for repeatable performance and because the skipping or slipping can accelerate the wear of the member  102  on the gears. 
     Engagement between the self-enclosed member  102  and the gears or wheels of the internal drive mechanisms  108  can be improved by having higher pressure between the rollers or skids  116  and the gears or wheels so that the member  102  is held tighter against the gears or wheels. Even if no skipping occurs, there can be a degree of wear on the self-enclosed member  102  by the gear or wheel contacting the teeth in normal use. As the wear on the self-enclosed member  102  advances, the member  102  outer surface can become cut and develop frayed edges on these cuts. This cutting and fraying can further decrease the engagement of the gears or wheels of the internal drive mechanism  108  and the self-enclosed member  102  until the member  102  slows and eventually stalls or the frayed ends become wrapped in the gear or wheel coupling and abruptly stalls the apparatus  100 . Thus,  FIG. 9  illustrates one way of reinforcing the self-enclosed member  102  to significantly increase its wear resistance and significantly decrease its elasticity, thereby improving its rotational and overall performance. 
       FIG. 8  illustrates a cross-sectional view of one example of a self-enclosed member  102  for use in a propellable apparatus  100 . In this sectional example, the self-enclosed member  102  is shown as a cylinder in an intermediate state during manufacture, before it is rolled into a toroid and seamed to itself. The self-enclosed member  102  can be made of a polymer such as a urethane (e.g., Stevens Urethane  1880  having a durometer of about 80-85 A, and produced by Stevens Urethane of Easthampton, Mass.). Urethanes are generally tough polymers with good flexibility, and this combination makes them adequate candidates for the self-enclosed member  102  material. 
       FIG. 9  illustrates a cross-sectional view of another example of a self-enclosed member  102  having a reinforcing member  902  (e.g., reinforcing mesh) embedded in the member  102  wall. As shown, the self-enclosed member  102  of this example includes three thicker walled sections  804  around its circumference with treads  802  in the sections  804  to match up and align with the gears or wheels of the internal drive mechanism  108  at three locations, for example, around the circumference of the propellable apparatus  100 . In this reinforcing example, a reinforcing member  902  is embedded in the sections  804  beneath the treads  802 . As such, the reinforcing member  902  is positioned under the gears or wheels, where it is effective both in enhancing durability and reducing the elasticity of the sections  804 . These reinforcing members  902  can be made from a variety of polymer meshes. Some candidate materials include, but are not limited to, peek, nylon, or polyester. In one example, the thickness of these thicker walled sections  804  can be about 0.012 inches and the reinforcing members  902  can be made of a weave of about 0.002 inch fibers in a 200×200 mesh. 
     The reinforcing members  902  can be molded into the self-enclosed member wall by, for example, layering strips of urethane around the reinforcing material inside a mold and then pressing and heating the layers together to melt the urethane and flow it in or around the reinforcing material. In the example shown, the reinforcing members  902  are only used under the treads  802  so the stiffer reinforcing material is not present in the thinner walled web sections  904  outside the gear paths and consequently doesn&#39;t impact the stiffness of the self-enclosed member  102  in these areas. It could also be beneficial to have the reinforcing members  902  cover a bigger area of the section  804  width, extend into or replace the web sections  904 , or be positioned in a different height in the thickness of the self-enclosed member  102 . 
     Closing Notes: 
     The present inventors have recognized that (1) it can sometimes be advantageous to attach the propellable apparatus at a front-end tip portion of a payload, (2) a propellable apparatus having a relatively short length (e.g., between about 0.8 inches and about 1.5 inches) does not limit articulation of a flexible payload, having a separately controllable articulating capability, an appreciable degree when it is mounted at or near the front-end thereof, (3) drive members made of flexible cable including wrapped filaments allows for adequate flexing without reaching unacceptable internal stress levels during rotation, (4) one or more wiper members can be added to the propellable apparatus, such as at one or both apparatus ends, to prevent tissue from engaging with the apparatus drive mechanism, (5) a tapered member can be added to a back-end of the propellable apparatus to facilitate removal of the apparatus from a cavity or lumen, and (6) one or more reinforcing members can be integrated within a self-enclosed member for increased durability and rotational use. 
     The above Detailed Description includes references to the accompanying drawings, which form a part of the Detailed Description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown and described. However, the present inventors also contemplate examples in which only those elements shown and described are provided. 
     All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated references should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls. 
     In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the term “back-end” is used to refer to a portion of a propellable apparatus, which is configured to be located closer to a cavity or lumen orifice after insertion of the apparatus therein. In contrast, the term “front-end” is used in this document to refer to a portion of the propellable apparatus, which is configured to be located farther from the cavity or lumen orifice after insertion and which leads the apparatus through the cavity or lumen. 
     In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, propellable apparatus, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.