Patent Publication Number: US-2021172557-A1

Title: Pipe traversing apparatus and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation patent application of U.S. application Ser. No. 16/583,579, filed Sep. 26, 2019, which is a continuation patent application of U.S. application Ser. No. 16/135,413, filed Sep. 19, 2018, now U.S. Pat. No. 10,465,835, granted Nov. 5, 2019, which claims the benefit of and priority to U.S. Provisional Application No. 62/560,265, filed Sep. 19, 2017, U.S. Provisional Application No. 62/616,147, filed Jan. 11, 2018, and U.S. Provisional Application No. 62/687,753, filed Jun. 20, 2018, all of which are hereby incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Many existing pipe crawling apparatuses are designed to either travel inside of pipes or are not equipped to travel around obstacles it may encounter on the outside of pipes. In view of limitations of current technologies, a need remains for pipe-crawling apparatus that are effective in navigating around and/or over potential obstacles, e.g., obstacles that present a change in the effective diameter of the pipe, a change in the effective curvature of the pipe, and/or obstacles that protrude from the pipe in one or more radial directions. More particularly, pipe-crawling apparatus are needed that are effective in navigating around and/or over flanges, valves, tees, bends, supports and the like. In addition, a need remains for pipe-crawling apparatus that are effective in traveling relative to pipes without magnets, vacuum or aerodynamic forces. Additionally, a need remains for pipe-crawling apparatus and associated systems that are effective in performing desired functions relative to the pipe itself, e.g., corrosion detection, wall thickness measurements, or based on travel along the path but independent of the pipe itself, e.g., imaging and/or sensing of locations accessible through travel along a pipe. These and other needs are advantageously satisfied by the apparatus and systems disclosed herein. 
     SUMMARY 
     The present disclosure is directed to a robotic apparatus for traversing the outer surface a pipe or similar structure. The robotic apparatus, in various embodiments, may comprise a first wheel assembly including a wheel and an alignment mechanism, and configured for positioning on a first side of a pipe; a second wheel assembly and a third wheel assembly, each including a wheel and an alignment mechanism, and configured for positioning on a second, opposing side of the pipe; and a clamping mechanism configured to apply a force for urging the second wheel and the third wheel to pivot in opposing directions towards a plane of the first wheel for securing the first wheel, the second wheel, and the third wheel to the pipe, wherein the alignment mechanisms are configured for selectably adjusting an orientation of the wheels to allow the robotic apparatus to move along a straight path or a helical path on the pipe. 
     In various embodiments, at least one of the wheels may have a concave shaped surface for engaging the pipe. At least one of the wheel assemblies, in various embodiments, may include a motor for rotating the wheel of the corresponding assembly. The motor, in an embodiment, may be situated inside of the wheel of the corresponding assembly. 
     The clamping mechanism, in various embodiments, may include one or more biasing members for generating the pulling force. The one or more biasing members, in some embodiments, may be configured to passively generate the pulling force and may, in an embodiment, include at least one of a tension spring, a compression spring, and a torsion spring. The one or more biasing members, in some embodiments, may be configured to actively generate the pulling force. 
     The clamping mechanism, in various embodiments, may include a first arm member connecting the first wheel assembly with the second wheel assembly; a second arm member connecting the first wheel assembly with the third wheel assembly; and one or more biasing members for applying a pulling force to engage the wheels on opposing sides of the pipe, the one or more biasing members either connecting the first arm member to the second arm member or connecting the first wheel assembly to the first arm member and to the second arm member. The clamping mechanism, in an embodiment, may further include a third arm member and a fourth arm member arranged parallel and adjacent to the first arm member and the second arm member, respectively, thereby forming first and second parallelogram-shaped linkages between the first wheel assembly and the second wheel assembly and between the first wheel assembly and the third wheel assembly, respectively, wherein the parallelogram-shaped linkages maintain the wheel assemblies in parallel alignment with one another regardless of a relative position of the wheel assemblies to one another. 
     The clamping mechanism, in various embodiments, may be offset from and parallel to a plane shared by the wheels. The robotic device, in various embodiments, may include an open side situated opposite the clamping mechanism, through which an obstacle extending from the pipe may pass unobstructed. The robotic apparatus, in various embodiments, may further include one or more members configured to extend across the open side of the robotic apparatus to prevent the robotic apparatus from falling off the pipe. The one or more members, in some embodiments, may be configured to pivot along a plane of the open side to accommodate passage of an obstacle through the open side of the robotic apparatus. 
     The alignment mechanism, in various embodiments, may be configured to adjust the orientation of a corresponding wheel in a rotational direction relative to an axis that is normal to the pipe. Adjusting the orientation of the wheels, in an embodiment, may cause the robotic apparatus to move along a helical path along the pipe. The alignment mechanism, in various embodiments, may include a wheel frame to which the wheel is rotatably coupled about a first axis; a base plate to which the wheel frame is rotatably coupled about a second axis orthogonal to the first axis; and a motor configured to rotate the wheel frame about the second axis, thereby adjusting the orientation of the wheel relative to the base plate. 
     The robotic apparatus, in various embodiments, may further include a sensor assembly for inspecting the pipe or an environment surrounding the pipe. The sensor assembly, in some embodiments, may include a sensor, an arm member rotatably coupling the sensor to the robotic apparatus, and an actuator configured to rotate the arm member about the rotatable coupling to move the sensor towards or away from the pipe. 
     In another aspect, the present disclosure is directed to a method for navigating an obstacle on a pipe with a robotic apparatus. The method, in various embodiments may comprise the steps of providing a robotic apparatus comprising: (i) a first wheel configured for positioning on a first side of the pipe, (ii) a second wheel and a third wheel configured for positioning on a second, opposing side of the pipe, and (iii) a clamping mechanism connecting the first wheel to the second and third wheels, and situated offset from and parallel to a plane shared by the wheels so as to define an open side situated opposite the clamping mechanism; advancing the robotic apparatus along a helical pathway on the pipe to position the open side of the robotic apparatus in longitudinal alignment with the obstacle on the pipe; and advancing the robotic apparatus along a straight pathway on the pipe such that the obstacle passes unobstructed through the open side of the robotic apparatus. 
     Advancing the robotic apparatus along a helical pathway, in various embodiments, may include adjusting an orientation of at least one of the wheels rotationally relative to an axis that is normal to the pipe. Advancing the robotic apparatus along a straight pathway on the pipe, in various embodiments, may include adjusting an orientation of the wheels to be in alignment with a longitudinal axis of the pipe. 
     The robotic apparatus, in various embodiments, may include one or more members configured to extend across the open side of the robotic apparatus to prevent the robotic apparatus from falling off the pipe, wherein advancing the robotic apparatus along a straight pathway on the pipe such that the obstacle passes unobstructed through the open side of the robotic apparatus includes allowing the one or more members to pivot along a plane of the open side to accommodate passage of the obstacle through the open side of the robotic apparatus. The method, in various embodiments, may further include adjusting an orientation of two or more of the wheels in opposing directions to advance the robotic apparatus sideways relative to a longitudinal axis of the pipe and thereby reposition the robotic apparatus on the pipe to account for wheel slip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative, non-limiting example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
         FIG. 1A ,  FIG. 1B ,  FIG. 1C ,  FIG. 1D , and  FIG. 1E  illustrate various obstacles that may be found along a piping system; 
         FIG. 2  is a perspective view of a robotic apparatus in accordance with an embodiment of the present disclosure; 
         FIG. 3A ,  FIG. 3B ,  FIG. 3C , and  FIG. 3D  depict various views of a robotic apparatus in accordance with an embodiment of the present disclosure; 
         FIG. 4A  is a cutaway view of an internal motor within a wheel in accordance with an embodiment of the present disclosure; 
         FIG. 4B  is a perspective view of a wheel assembly in accordance with an embodiment of the present disclosure; 
         FIG. 5A ,  FIG. 5B , and  FIG. 5C  depict various views of a robotic apparatus attached to a pipe in accordance with an embodiment of the present disclosure; 
         FIG. 6A  and  FIG. 6B  depict a robotic apparatus on a smaller diameter pipe and a larger diameter pipe in accordance with an embodiment of the present disclosure; 
         FIG. 7  illustrates a robotic apparatus with wheel alignment adjusted for helical travel along a pipe in accordance with an embodiment of the present disclosure; 
         FIG. 8A ,  FIG. 8B ,  FIG. 8C ,  FIG. 8D ,  FIG. 8E , and  FIG. 8F  illustrate the robotic apparatus following a helical path to pass an obstacle in accordance with an embodiment of the present disclosure; 
         FIG. 9A ,  FIG. 9B ,  FIG. 9C ,  FIG. 9D ,  FIG. 9E ,  FIG. 9F ,  FIG. 9G ,  FIG. 9H  illustrate the robotic apparatus passing an obstacle in accordance with an embodiment of the present disclosure; 
         FIG. 10A ,  FIG. 10B , and  FIG. 10C  depict a fail-safe mechanism in accordance with an embodiment of the present disclosure; 
         FIG. 11A ,  FIG. 11B ,  FIG. 11C , and  FIG. 11D  illustrate a fail-safe mechanism allowing passage of an obstacle in accordance with an embodiment of the present disclosure; 
         FIG. 12A ,  FIG. 12B ,  FIG. 12C , and  FIG. 12D  illustrate the robotic apparatus navigating a bend in a pipe in accordance with an embodiment of the present disclosure; 
         FIG. 13A  and  FIG. 13B  depict a sensor assembly in a lowered and raised position in accordance with an embodiment of the present disclosure; 
         FIG. 14A ,  FIG. 14B ,  FIG. 14C , and  FIG. 14D  depict another sensor assembly in accordance with an embodiment of the present disclosure; 
         FIG. 15A ,  FIG. 15B ,  FIG. 15C , and  FIG. 15D  depict a robotic apparatus translating to account for wheel slip in accordance with an embodiment of the present disclosure; 
         FIG. 16  is a cutaway view of gears of a clamping mechanism in accordance with an embodiment of the present disclosure; 
         FIG. 17  is a perspective view of a clamping mechanism in accordance with an embodiment of the present disclosure; 
         FIG. 18  is a side view of clamping mechanism in accordance with another embodiment of the present disclosure; 
         FIG. 19A  depicts a robotic apparatus navigating a small protrusion from a pipe in accordance with an embodiment of the present disclosure; 
         FIG. 19B  depicts a robotic apparatus navigating a bend in a pipe in accordance with an embodiment of the present disclosure; 
         FIG. 20  and  FIG. 21  depict side views of the prototype of robotic apparatus  100 , with wheels  110  aligned for straight travel along pipe  10 , in accordance with an embodiment of the present disclosure; 
         FIG. 22  depicts a bottom view of the prototype of robotic apparatus  100 , with the orientation of wheels  110  adjusted for helical travel along pipe  10  in accordance with an embodiment of the present disclosure; 
         FIG. 23  depicts a side view of the prototype of robotic apparatus  100  navigating a bend in pipe  10  in accordance with an embodiment of the present disclosure; and 
         FIG. 24  depicts a side view of the prototype of robotic apparatus  100 , with open side  102  positioned for passing an obstacle protruding from pipe  10  in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are directed to a robotic apparatus for traversing the exterior of piping systems, such as ones commonly found in chemical plants, power plants, manufacturing plants, and infrastructure. Piping systems can be complex and present various obstacles that can make it difficult to traverse individual pipes in an efficient and effective manner. For example, as shown in  FIG. 1A ,  FIG. 1B ,  FIG. 1C ,  FIG. 1D , and  FIG. 1E , representative obstacles may include supports  11  ( FIG. 1A ), junctions  12  ( FIG. 1B  and  FIG. 1C ), flanges  13  ( FIG. 1C ), valves  14  ( FIG. 1C ), vents or bleeders (similar to smaller valves), changes in diameter  15  ( FIG. 1D ), and bends  16  ( FIG. 1E ), amongst others. Various embodiments of the robotic apparatus may be configured to traverse pipes  10  and navigate such obstacles as encountered through a unique architecture and approach, as later described in more detail. 
     Embodiments of the present disclosure are directed to a robotic apparatus that may also traverse the exterior of other structures that are similarly shaped, such as structural cables (e.g. on suspension bridges), structural beams, powerlines, underwater cables and underwater piping systems. 
     Embodiments of the present disclosure may be useful in many applications including, without limitation:
         Pipeline inspection using cameras, non-destructive testing (NDT or NDI), or other sensors;   Inspecting equipment in the vicinity of the piping system   Performing maintenance on the piping system (e.g., cleaning the external surface, removing insulation, applying a patch/clamp to stop a leak)   Transporting tools or equipment along the piping system (e.g., facilitating installation of sensors on the pipe).       

     Various embodiments of the robotic apparatus may be capable of traversing pipes arranged in any orientation (including horizontal and vertical), and pipes made of any material (e.g., steel, aluminum), even those with insulation about the exterior of the pipe. Insulation is typically a semi-rigid material, such as a mineral wool or calcium silicate, protected by a thin metal jacket, such as aluminum or stainless steel. 
     Generally speaking, embodiments of the robotic apparatus of the present disclosure may attach to a pipe by applying a clamping force on opposing sides of the pipe. Various embodiments may be capable of holding a static position on the pipe and may support its own weight on a range of pipe sizes in any orientation (e.g., horizontal or vertical). The robotic apparatus, in various embodiments, may be configured to drive along a path in the longitudinal direction of the pipe, as well as along a helical path (i.e., circumferential and longitudinal), on pipes of varying sizes and orientation. Such maneuvering, in combination with the ability to expand or contract the clamping mechanism around the pipe, and an open-sided architecture, may allow the robotic apparatus to navigate a variety of bends and obstacles encountered along the length of the pipe. A low profile of the robotic apparatus may enable it to drive along pipes in close proximity to other pipes or obstacles situated close by, and an optional fail-safe mechanism may be included to prevent the robotic apparatus from falling to the ground in the event its wheels decoupled from the pipe. The robotic apparatus may additionally be capable of actively sensing and controlling the amount of clamping force it exerts on the pipe, thereby minimizing the risk that its wheels slip along the pipe while ensuring that the robotic apparatus does not damage the pipe or insulation. Further, the robotic apparatus may be capable of actively sensing whether the wheels slip on the pipe surface and actively control individual wheels to steer the robotic apparatus back to the centerline of the pipe. 
     In various embodiments, the robotic apparatus may be configured to carry and deploy a payload along the pipe, such as cameras (e.g. visual spectrum and IR cameras), various sensors like NDT sensors (e.g., ultrasonic testing probes, pulsed eddy current probes, digital radiography equipment, acoustic sensors) and lower explosive limit (LEL) sensors for the purpose of inspecting the piping system or equipment in its vicinity, and/or other payloads like tools and equipment. The robotic apparatus, in various embodiments, may include an onboard power supply (e.g., batteries) and operate via wireless communication with an operator, thereby obviating the need for a power cord or tether. 
     High-Level Architecture 
     Referring now to  FIG. 2 , robotic apparatus  100  of the present disclosure may generally include two or more wheel assemblies  101  configured for positioning on opposing sides of pipe  10 , and a clamping mechanism  150  for adjusting the distance between the two or more wheel assemblies to secure robotic apparatus  100  to pipe  10 . One or more wheels of the two or more wheel assemblies  101  may be powered such that robotic apparatus may traverse along pipe  10  in a longitudinal direction. The wheels, in various embodiments, may be reoriented to allow robotic apparatus  100  to move along a helical path on pipe  10 , and thereby position robotic apparatus  100  to pass over a particular portion(s) of pipe  10  and/or avoid an obstacle(s) extending from a surface of pipe  10 , as later described in more detail. 
       FIG. 3A ,  FIG. 3B ,  FIG. 3C , and  FIG. 3D  depict several views of a representative embodiment of robotic apparatus  100 . The representative embodiment shown includes three wheel assemblies  101   a,    101   b,    101   c  arranged in a triangular configuration in a common plane (“wheel engagement plane”  104 ), such that wheel assembly  101   a  is positioned for engaging a first side of pipe  10 , and wheel assemblies  101   b,    101   c  are positioned for engaging a second, opposing side of pipe  10 . Clamping mechanism  150  is offset from the wheel engagement plane  104  and couples wheel assemblies  101   a,    101   b,    101   c.  As configured, wheel assemblies  101   a,    101   b,    101   c  may traverse along an outer portion of pipe  10 , while the offset positioning of clamping mechanism  150  allows clamping mechanism  150  to travel through the air or water alongside pipe  10 . The present configuration provides robotic apparatus  100  with an open side  102  (as best seen in  FIG. 5C ), situated opposite clamping mechanism  150 , through which an obstacle extending from the outer surface of pipe  10  may pass unobstructed, thereby allowing robotic apparatus to traverse such obstacles on pipe  10  as later described in more detail. 
     Wheel Assembly  101   
     Still referring to  FIG. 3A ,  FIG. 3B ,  FIG. 3C , and  FIG. 3D , each wheel assembly  101  may generally include a wheel  110  and an alignment mechanism  120 . Generally speaking, wheel  110  may be configured to engage and rotate along an outer surface of pipe  10 , and alignment mechanism  120  may be configured to adjust an orientation of wheel  110  and thereby define a path to be followed by robotic apparatus as it traverses pipe  10 . 
     Wheel  110 , in various embodiments, may include any rotatable body suitable for engaging and rotating along an outer surface of pipe  10 . To that end, wheel  110  may generally include a rotating body with a contact surface  112 , and may be rotatably coupled with a wheel frame  114 . 
     Wheel  110  may be of any shape and construction suitable for the aforementioned purpose such as, without limitation, disc- or cylindrical-shaped. While standard wheels may be utilized, in various embodiments, it may be advantageous for wheel  110  to have a shape specifically designed to accommodate, and thereby more effectively engage, the rounded shape of the outer surface of pipe  10 . To that end, in various embodiments, contact surface  112  may be substantially inverted (e.g., v-shaped, hourglass shaped), with contact surface  112  having a concave curvature dimensioned to conform to the rounded shape of pipe  10 . As best shown in  FIG. 5C , the hourglass shape of contact surface  112  may serve to maximize the contact area between wheel  110  and pipe  10  compared with a standard cylindrical wheel with a flat or convex contact surface, as the hourglass shaped contact surface  112  of the present disclosure essentially wraps around the curvature of pipe  10 , providing contact with not just the center of the pipe, but also with the top quarters as well. By enhancing overall contact area between wheel  110  and pipe  10 , more friction is available to securely couple robotic apparatus  100  to pipe  10 . By distributing the contact area between wheel  110  and pipe  10  around the circumference of the pipe, wheel  110  has a favorable lever arm to support off-axis forces, such as the typical force from the clamping mechanism. Thus, the wheel&#39;s shape allows robotic apparatus  100  to maintain a given circumferential orientation on pipe  10  (e.g., upright, canted diagonally) without slipping upside-down on pipe  10 . 
     Further, the hourglass shape of contact surface  112 , in various embodiments, may act to automatically center wheel  110  along a longitudinal centerline of pipe  10 , as shown in  FIG. 5C . As configured, wheel  110  may be less likely to disengage from pipe  10  entirely, as contact between the inwardly sloping contact surface  112  and the rounded surface of pipe  10  may bias wheel  110  to center itself over the longitudinal centerline of pipe  10 . This may be particularly beneficial in embodiments in which wheel assemblies  101  are arranged within a common engagement plane  104 , as shown, since such a configuration generally clamps on pipe  10  from two radial directions instead of three or more radial directions were wheel assemblies  101  to be positioned in more than two circumferential positions about pipe  10 . Still further, contact surface  112  may be shaped and dimensioned such that it functions effectively on a range of pipe sizes. The straight edges of the wheel profile, as seen from a direction normal to the concentric axis of the wheel, may be purposefully chosen so that the angular distance between the contact points with respect to the center of the pipe is constant for any pipe size. However, the linear distance between the contact points increases with the pipe size in a manner such that the range of pipe sizes on which wheel  110  is effective is limited by the total width of wheel  110 . 
     The shape of contact surface  112  may be especially suitable for helical motion around a pipe, including the helical motion that robotic apparatus  100  may exhibit. Consider the plane that includes the central axis of the wheel and a vector that is normal to the surface of the pipe. When the wheel is oriented to drive straight along the longitudinal axis of the pipe the cross-section of the pipe in the aforementioned plane is a circle. When the wheel is oriented to drive at an angle with respect to the longitudinal axis of the pipe the cross-section of the pipe in the aforementioned plane is an ellipse. This effectively changes the curvature of the section of the pipe that the wheel is driving on, similar to how a change in pipe size changes the pipe&#39;s curvature. Similar to how the wheel can adapt to a range of pipe sizes, it can also adapt to a range of turning angles that effectively change the curvature of the pipe under the wheel. In general, the contact area between the wheel and the pipe increases as the curvature decreases. Hence, the contact area increases as the pipe size increases and as the angle between the wheel&#39;s direction of travel and the longitudinal axis of the pipe increases. 
     Alignment mechanism  120 , in various embodiments, may include any mechanism suitable for adjusting an orientation of wheel  110 , and thereby define a path to be followed by robotic apparatus as it traverses pipe  10 . In particular, alignment mechanism  120 , in various embodiments, may be configured to adjust the orientation of an associated wheel  110  rotationally, with respect to an axis that is normal to pipe  10 , to steer robotic apparatus along pipe  10 . That is, alignment mechanism  120 , in various embodiments, may adjust the orientation of an associated wheel  110  about a yaw axis  103  of robotic apparatus  100  (shown in  FIG. 3C ,  FIG. 5C ,  FIG. 8A ,  FIG. 8B ,  FIG. 8C ,  FIG. 8D ,  FIG. 8E , and  FIG. 8F ) such that wheel  110  is reoriented clockwise or counterclockwise about an axis extending normal to the underlying surface of pipe  10 . As configured, alignment mechanism  120  may adjust wheel  110  orientation to traverse pipe  10  along a straight pathway (i.e., wheel  110  orientation aligned with yaw axis  103  of robotic apparatus  100  and longitudinal axis of pipe  10 ) or along a helical pathway (i.e., yawed wheel  110  orientation, adjusted clockwise or counterclockwise relative to an axis extending normal to the underlying surface of pipe  10 ). 
     Referring to  FIG. 4B , in an embodiment, alignment mechanism  120  may include a motor  122  and a base plate  124  to which wheel frame  114  may be rotatably coupled. Motor  122  may engage wheel frame  114  to rotate wheel frame relative to base plate  124 , and thereby adjust an orientation of wheel  110  relative to base plate  124 . In the embodiment shown, base plate  124  may be fixedly coupled to clamping mechanism  150 , and wheel  110  may be reoriented relative to robotic apparatus as a whole. To facilitate engagement between motor  122  and wheel frame  114 , each may be provided with gear teeth  123 ,  116 , respectively, which may be interfaced with one another such that rotation of motor  122  causes rotation of wheel frame  114  about an axis normal to base plate  124 . Of course, this is merely an illustrative embodiment of a suitable mechanism for adjusting an orientation of wheels  110  of robotic apparatus  100 , and one of ordinary skill in the art will recognize other suitable alignment mechanisms within the scope of the present disclosure. 
     In certain scenarios, one or more alignment mechanisms  120  may be configured to individually adjust the respective orientations of wheels  110  by different amounts and/or in different directions. When all wheels  110  are turned by the same amount in the same clockwise or counter-clockwise direction, robotic apparatus  100  may travel along a helical pathway. In contrast, when wheels  110  are oriented in opposite directions, such that the wheels  110  on one side of pipe  10  turn in one direction (e.g. clockwise) and the wheels on the opposite side of pipe  10  turn in the opposite direction (e.g. counter-clockwise), robotic apparatus  100  may travel along a different pathway. In the latter case, wheels  110  may travel such that robotic apparatus  100  moves along the longitudinal axis of pipe  10  and translates sideways with respect to the same axis. This may be beneficial if wheels  110  slip, for example due to the weight of robotic apparatus  100 , away from the centerline of pipe  10 . This method for self-adjusting the position of robotic apparatus  100  on the pipe is later illustrated in  FIG. 15A ,  FIG. 15B ,  FIG. 15C , and  FIG. 15D . 
     According to exemplary embodiments of the present disclosure, the angular orientation of the wheels may “lock” once axial movement of robotic apparatus  100  on pipe  10  commences. In this way, the desired travel pattern, e.g., helical travel with a 5° off-axis alignment of wheels  110 , may be maintained as robotic apparatus  100  moves along pipe  10 . Various locking features may be employed to detachably secure wheel frame  114  (and thus wheel  110 ) in the desired angular orientation, as will be apparent to persons skilled in the art. 
     Wheel assembly  101 , in various embodiments, may further include a motor  130  for driving rotation of wheel  110 . Motor  130  may include any motor such as, without limitation, a brushed DC motor or the like, suitable for driving rotation of an associated wheel  110  of wheel assembly  101 . 
     As shown in  FIG. 3A ,  FIG. 3B , and  FIG. 3C , in various embodiments, motor  130  may be positioned external to wheel  110  and connected thereto via a traditional drive train for rotating wheel  110 . Motor  130 , in other embodiments, may instead be packaged within wheel  110 , as shown in  FIG. 4A  and  FIG. 4B . In particular, motor  130  may be placed inside wheel  110  with its output shaft  132  concentric to the rotation axis  131  of wheel  110 , as shown. Motor  130  may be rigidly mounted to a cylindrical housing  134 , which is designed to attach to wheel frame  114 . As configured, cylindrical housing  134  may act as a shaft that supports wheel  110  through a set of bearings (e.g. tapered roller bearings)  136  while allowing wheel  110  to rotate with respect to cylindrical housing  134 . Output shaft  132  of motor  130  may be coupled to wheel  110 , as shown, so that motor  130  can control the rotation of wheel  110 . Output shaft  132  of motor  130 , in various embodiments, may also be favorably supported by wheel frame  114  through an additional bearing (e.g. roller bearing)  138 . 
     Wheel assembly  101  may further include one or more controllers (not shown) for controlling operation of motor(s)  130 , such as rotational speed, torque, and the like. The controllers may receive commands from various locations. For example, one of the controllers mounted with respect to robotic apparatus  100  may function as a “master” controller, and the other controllers may function as “slave” controllers, such that the slave controllers respond to commands received from the master controller. Alternatively, each of the controllers may operate independently and may receive independent commands. The commands may be remotely transmitted, e.g., by wireless (or wired) communication, as is known in the art. The commands may also be pre-programmed, in whole or in part, in the controller(s), e.g., time-based commands to operate according to clock-based criteria. 
     Although exemplary robotic apparatus  100  is depicted with three motors  130 , the disclosed apparatus may be implemented such that a motor is provided for less than all wheels associated with the apparatus. For example, a single drive motor  130  associated with a single wheel  110  may be provided, and the other wheels  110  may rotate in response to movement that is initiated by the single motor  130  (and associated wheel  110 ). Similarly, a pair of motors  130  may be provided for an apparatus that includes three wheels  110 , such that two wheels  110  may receive drive force from associated motors  130 , while the third wheel  110  rotates in response to movement of the apparatus relative to the pipe  10 . 
     In exemplary embodiments of the present disclosure, the relative speed of the individual wheels  110  may be controlled so as to enhance the operation of the apparatus. For example, it may be desired to drive the center wheel (e.g., that of wheel assembly  101   a ) faster than either of the outer wheels (e.g., those of wheel assemblies  101   b,    101   c ) when navigating a turn or bend in the pipe  10 . In such circumstance, the controllers may be programmed to increase the drive force to the center wheel  110  and/or reduce the drive force to outer wheel(s)  110 . Alternatively, it may be desirable to drive the outer wheels  110  faster than the center wheel  110  when navigating a turn or bend in the pipe  10 . In such circumstance, the controllers may be programmed to increase the drive force to the outer wheel(s)  110  and/or reduce the drive force to the center wheel  110 . The noted adjustments may be initiated manually, e.g., by an operator, or may be initiated automatically, e.g., based on sensing mechanism(s) associated with the assembly that identify a turn/bend in the pipe  10  (e.g., based on sensing of the angular orientation of one or more aspects of the apparatus). 
     Clamping Mechanism  150   
     Referring ahead to  FIG. 5A ,  FIG. 5B , and  FIG. 5C , clamping mechanism  150  of robotic apparatus  100 , in various embodiments, may generally include one or more arm members  152  and one or more biasing members  154 . Arm member(s)  152 , in various embodiments, may connect wheel assemblies  101  on opposing sides of pipe, and biasing member(s)  154  may apply a pulling or pushing force on arm members  152  that causes the wheel assemblies to engage the opposing sides of pipe  10 , thereby securing robotic apparatus  100  to pipe  10  as later described in more detail. 
     Arm members  152 , in various embodiments, may be arranged in pairs, with the members of a given pair arranged parallel to one another and separated by a gap, as shown in  FIG. 5A . The ends of each member  152  in a given pair may be rotatably coupled with the associated wheel assemblies  101  such that the given pair forms a parallelogram-shaped linkage between the corresponding wheel assemblies  101 . The parallelogram-shaped linkage, in an embodiment, may act to keep the connected wheel assemblies  101  in parallel alignment with one another on either side of pipe  10  regardless of the relative positions of the connected wheel assemblies  101  (which may change with pipe diameter, as later described). By keeping the connected wheel assemblies  101  in parallel alignment with one another on opposing sides of pipe  10 , the associated wheels  110  may more effectively engage the surface of pipe  10  and securely couple robotic apparatus  100  thereto. Additionally, keeping the connected wheel assemblies  101  in parallel alignment with one another is important for the alignment mechanism  120  to function properly. That is, yaw axis  103  about which alignment mechanism  120  turns wheel  110  should be normal to the surface of pipe  10 . 
     For example, in  FIG. 5A , arm members  152   a,    152   b  form a pair with the aforementioned arrangement, and connect wheel assembly  101   a  with wheel assembly  101   b.  As configured, wheel assembly  101   b  may pivot clockwise (e.g., up and to the left) relative to wheel assembly  101   a  to engage a narrow diameter pipe  10 , or may pivot counterclockwise (e.g., down and to the right) relative to wheel assembly  101   a  to engage a larger diameter pipe, and vice versa. As wheel assemblies  101   a,    101   b  pivot relative to one another, the parallelogram-shaped linkage formed by arm members  152   a,    152   b  causes the connected wheel assemblies  101   a,    101   b  to remain in parallel alignment with one another on either side of pipe  10 , thereby ensuring that wheel  110  of each remains flush and engaged with pipe  10 . Similarly, arm members  152   c,    152   d  form a pair with the aforementioned arrangement, and connect wheel assembly  101   a  with wheel assembly  101   c.  As configured, wheel assembly  101   c  may pivot counterclockwise (e.g., up and to the right) relative to wheel assembly  101   a  to engage a narrow diameter pipe  10 , or may pivot clockwise (e.g., down and to the left) relative to wheel assembly  101   a  to engage a larger diameter pipe, and vice versa. As wheel assemblies  101   a,    101   c  pivot relative to one another, the parallelogram-shaped linkage formed by arm members  152   b,    152   c  causes the connected wheel assemblies  101   a,    101   c  to remain in parallel alignment with one another on either side of pipe  10 , thereby ensuring that wheel  110  of each remains flush and engaged with pipe  10 . 
     Of course, in various embodiments, a single arm member  152  (as opposed to the aforementioned pairs) may be used connect two wheel assemblies  101 . In such embodiments (not shown), alternative approaches may be employed to maintain the connected wheel assemblies  101  in parallel alignment, if desired. For example, a single arm member  152  may be used with a pair of wires in the same plane as the aforementioned pairs. The wires may attach directly to wheel assemblies  101  on each side of arm member  152 . While arm member  152  would provide the necessary structural integrity, the wires would engage when arm member  152  pivoted and (based on the same kinematics as the parallelogram-shaped linkage) keep the connected wheel assemblies  101  in parallel alignment with one another. It should be recognized that two wires may be be needed since wires typically only carry loads in tension, not compression. 
     Biasing members  154 , in various embodiments, may be configured to apply a force for pulling opposing wheel assemblies  101  toward opposing sides of pipe  10  to secure robotic apparatus  100  to pipe  10 . Biasing members  154  may include any mechanism suitable for this purpose such as, without limitation, a gas tension spring (shown in  FIG. 5A ,  FIG. 5B , and  FIG. 5C ), tension springs (shown in  FIG. 17 ), compression springs, torsion springs, or any combination thereof. Additionally or alternatively, biasing mechanisms  154  may include one or more active biasing members (as opposed to the immediately aforementioned passive biasing members) such as a motorized pulley system, motorized lead screw, or a pneumatic/hydraulic actuator, or the like. 
     Clamping mechanism  150  as configured may automatically adjust the positions of wheel assemblies  101  relative to one another to accommodate pipes of varying diameters. For example, robotic apparatus  100  may compress significantly to accommodate small diameter pipes, resulting in a configuration in which wheel assemblies  101   b,    101   c  are nearly coplanar with wheel assembly  101   a  along a longitudinal axis of pipe  10  (i.e., separated by the small diameter of pipe  10 ), but are situated far away from wheel assembly  101   a  along a longitudinal axis of pipe  10 , as shown in  FIG. 6A . Conversely, robotic apparatus  100  may expand significantly to accommodate large diameter pipes, resulting in a configuration in which wheel assemblies  101   a,    101   b,    101   c  are situated close to one another along a longitudinal axis of pipe  10 , but wheel assembly  101   a  is situated far from wheel assemblies  101   b,    101   c  (i.e., separated by the large diameter of pipe  10 ) , as shown in  FIG. 6B . Biasing members  154   a,    154   b,    154   c,    154   d,  as configured, may continuously apply the pulling force between wheel assembly  101   a  and each of wheel assemblies  101   b,    101   c,  thereby securely coupling (or “clamping”) robotic apparatus  100  to pipe  10 , regardless of its orientation about the circumference of pipe  10  and regardless of whether pipe  10  is oriented horizontally or vertically. 
     Referring back to  FIG. 5A ,  FIG. 5B , and  FIG. 5C , in a representative embodiment, biasing mechanism  154  may include a gas tension spring. As shown, the gas tension spring may couple the one or more arms  152  extending from wheel assemblies  101   b,    101   c  to wheel assembly  101   a.  As the gas tension spring exerts a pulling force on the arm members  152  it creates a torque about the pivot points where the arm members  152  attach to the wheel assembly  101   a.  This torque will act to pull wheel assemblies  101   b,    101   c  outwards and upwards relative to wheel assembly  101   a,  causing robotic apparatus  100  to compress onto pipe  10 . 
     Referring ahead to  FIG. 16 , in an embodiment, clamping mechanism  150  may include a set of gears that attach to the axles that connect the arm members  152   b,    152   d  to the wheel assembly  101   a.  These gears are included to ensure that the arm members  152   a,    152   b,    152   c,    152   d  pivot by the same angular displacement and the clamping mechanism  150  remains symmetrical with respect to wheel assembly  101   a.  The arm members  152  need to pivot by the same angular displacement so that the connected wheel assemblies  101  are not only in parallel alignment with respect to each other, but also with respect to pipe  10 . In the alternative embodiment of  FIG. 17  (later described), a specific mechanism is not needed to ensure that the member arms pivot equally. That is, if equal biasing members  154  connect the  101   a  wheel assembly to each of the sets of arm members  152  (in contrast to one biasing member that connects the arm members  152  directly to each other, as shown in  FIG. 5A ,  FIG. 5B , and  FIG. 5C ) they will turn the arm members  152  by the same angular displacement since that is the energetically most favorable position. 
     In an alternative embodiment the biasing member(s) is an actively controlled actuator, such as a linear actuator (lead/ball/roller screw), rack-and-pinion, worm drive, or hydraulic/pneumatic actuator. The advantages of an actively controlled biasing member include the lower likelihood of exerting a force that is too small or too large. If the clamping force is too small the wheels will start to slip on the pipe. If the clamping force is too large it places unnecessary stress on the clamping mechanism and it increases the risk of deforming and/or damaging the pipe, the pipe insulation, or other equipment. With an actively controlled biasing member the force exerted can be adjusted in real time based on sensor values (e.g. wheel slip sensors), based on environmental conditions (e.g. higher clamping force is needed if rain makes the pipes slippery), and/or visual observations from the operator (e.g. lower clamping force is recommended if insulation deformation is observed). An actively controlled biasing member can also facilitate the process of attaching and detaching the robotic apparatus to the pipe, while a passive biasing member necessitates the use of a clamp or similar device to attach and detach the apparatus to the pipe. An actively controlled biasing member can also be designed to exert the appropriate force on a wide range of pipe sizes, while a passive biasing member usually has a more limited range of pipe sizes on which it exerts the appropriate amount of force. The two main disadvantages of an actively controlled biasing member are the following. Firstly, actively controlled actuators typically don&#39;t move as fast as passive biasing members. When the robotic apparatus drives around a bend it is especially important to be able to close the clamping mechanism quickly to maintain contact between the wheels and the pipe. Secondly, actively controlled apparatuses are mechanically and electronically more complex, and are therefore more prone to failure. 
     Referring ahead to  FIG. 17 , in another alternative embodiment, one or more biasing members  154  may connect a wheel assembly  101  situated on a first side of pipe  10  with arm member(s)  152  extending to a wheel assembly  101  situated on a second, opposing side of pipe  10 , as shown. Of course, in various embodiments, biasing members  154  may additionally or alternatively connect opposing wheel assemblies directly (or even associated structure) to similar effect. For example, in the embodiment of  FIG. 17 , biasing members  154   a,    154   b  (shown here as tension springs) may connect wheel assembly  101   a  to arm members  152   a,    152   b  extending to wheel assembly  101   b,  and biasing members  154   c,    154   d  may connect wheel assembly  101   a  to arm members  152   c,    152   d  extending to wheel assembly  101   c.  More specifically, first ends of biasing members  154   a,    154   b,    154   c,    154   d  each connect to a strut  156  extending longitudinally from wheel assembly  101   a,  and second ends of biasing members  154   a,    154   b,    154   c,    154   d  each connect to a mid or distal portion of arm members  152   a,    152   b,    152   c,    152   d,  respectively. Such an arrangement ensures that the vectors of the associated pulling force generated by biasing members  154   a,    154   b  and biasing members  154   c,    154   d  will act to pull wheel assemblies  101   b,    101   c,  respectively, outwards and upwards relative to wheel assembly  101   a  (while simultaneously pulling wheel assembly  101   a  downwards), causing robotic apparatus  100  to compress onto pipe  10  as shown in  FIG. 17 . 
       FIG. 18  illustrates yet another alternative embodiment of clamping mechanism  150 . While this embodiment of clamping mechanism  150  is shown on a four-wheeled robotic apparatus  100 , one of ordinary skill in the art will recognize that the present embodiment may be adapted to robotic apparatuses  100  having three wheels or greater than four wheels without diverging from the scope of the present disclosure. 
     In this embodiment, clamping mechanism  150  may generally include a motor  180  for driving a lead screw  181 , which in turn moves a plurality of linear arm pairs  182   a,    182   b,    182   c  to expand or compress clamping mechanism  150 . More specifically, wheel assemblies  101   a  and  101   b  may be coupled to a first frame  183   a,  thereby defining a first frame assembly  184   a,  and wheel assemblies  101   c,    101   d  may be coupled to a second frame  183   b,  thereby defining a second frame assembly  184   b.  Each of the linear arms  182  may have a first end  185  rotatably coupled to either the first frame  183   a  or the second frame  183   b,  and a second end  186  rotatably and slidably coupled to a linear guide  187 , as shown. Second ends  186  of at least some of the plurality of linear arms  182  may be operably coupled to lead screw  181  such that rotation of lead screw  181  causes the operably coupled second ends  186  to move from a first position on linear guide  187  to a second position on linear guide  187 , thereby changing the angle of each of the linear arms  182  in each pair relative to one another. As the angle between of linear arm  182  of each pair changes, the distance between first frame assembly  184   a  and second frame assembly  184   b  is adjusted. For example, driving lead screw  181  in a first direction may cause the operably coupled second ends  186  to move inwards along linear guide  187 , causing the angle between the linear arms  182  of each pair to increase as each arm  182  becomes more perpendicular to linear guide  187 . This may cause first frame assembly  184   a  and second frame assembly  184   b  to move further away from linear guide  187 , thereby expanding robotic apparatus  100 . Conversely, driving lead screw  181  in a second, opposing direction may cause the operably coupled second ends  186  to move outwards along linear guide  187 , causing the angle between the linear arms  182  of each pair to decrease as each arm  182  becomes more parallel to linear guide  187 . This may cause first frame assembly  184   a  and second frame assembly  184   b  to move closer to linear guide  187 , thereby compressing robotic apparatus  100 . By adjusting the distance between the first frame assembly  184   a  and the second frame assembly  184   b,  clamping mechanism  150  can accommodate various diameter pipes  10  and navigate bends as shown in  FIG. 19B  and described throughout the present disclosure. 
     Referring now to  FIG. 19A , additionally or alternatively, in an embodiment, less than all of second ends  186  may be operatively connected to lead screw  181 . As configured, those second ends  182  not operatively connected to lead screw  181  may freely translate along linear guide  187  and thereby allow at least one of first assembly  184   a  and second assembly  184   b  to pivot relative to one another. This, in turn, may allow robotic apparatus to traverse small obstacles protruding from the pipe while maintaining all but one wheel  110  in contact with the surface of pipe  10  at all times. For example, still referring to  FIG. 19A , wheel assembly  101   c  may climb the small protruding obstacle, causing second frame assembly  184   b  to pivot. This pivoting of second frame assembly  184   b  allows wheel assembly  101   d  to remain in contact with the underside of pipe  10 . Further, the pivoting of second frame assembly  184   b  relative to first frame assembly  184   a  also allows wheel assemblies  101   a,    101   b  to remain in contact with the upper side of pipe  10  while wheel assembly  101   c  traverses the obstacle. Similarly, frame assemblies  184   a,    184   b  will pivot relative to one another as wheel assembly  101   d  subsequently traverses the obstacle and thus wheel assemblies  101   a,    101   b,  and  101   c  will remain in contact with pipe  10 . 
     Traversing Pipeline and Avoiding Obstacles 
     In operation, robotic apparatus  100  may be mounted on an exterior surface of pipe  10  and traverse pipe  10  to deliver, perform, and/or support various functionalities, such as inspecting pipe  10  for structural defects or corrosion, and sampling the surrounding environment for traces of fluids that may have leaked from pipe  10 . In doing so, robotic apparatus  100  may at times may need to reposition itself circumferentially on pipe  10  to, for example, navigate one or more obstacles extending from pipe  10  or to inspect a particular side(s) of pipe  10 . Similarly, at times it may be advantageous for robotic apparatus to corkscrew or otherwise follow a helical pattern about the exterior of pipe  10  when attempting to inspect the majority of the exterior of pipe  10  or the surrounding environment. Accordingly, robotic apparatus  100  of the present disclosure may be configured to traverse pipe  10  along straight and helical paths. Generally speaking, travel along these paths may be accomplished by driving one or more of wheels  110  using motor(s)  130  and steering wheels  110  using alignment mechanisms  120 , as further described in more detail below. 
     To follow a straight path along pipe  10 , alignment mechanisms  120  may orient wheels  110  to be aligned with the longitudinal axis of pipe, as shown in  FIG. 5A ,  FIG. 5B  and  FIG. 5C . As configured, the hourglass shape (if equipped) may center wheels  110  on opposing sides of pipe  10  and steer robotic apparatus along a straight path such that wheels  110  continue following those particular opposing sides (e.g., the top and bottom of pipe  10  as shown). 
     Referring now to  FIG. 7 ,  FIG. 8A ,  FIG. 8B ,  FIG. 8C ,  FIG. 8D ,  FIG. 8E , and  FIG. 8F , to follow a helical path, whether for the purposes of following a helical inspection pattern or simply to reposition robotic apparatus about the circumference of pipe  10 , alignment mechanisms  120  may adjust the orientation of wheels  110  rotationally relative to yaw axis  103  of robotic apparatus  100 , which in the present embodiment coincides with engagement plane  104 . Alignment mechanisms  120 , in various embodiments, may adjust the orientation of wheels  110  rotationally (i.e., clockwise or counter-clockwise). For example, in an embodiment, alignment mechanism  120  may adjust the orientation of wheels  110  to the left to guide robotic apparatus  100  along a helical path with coils moving in a counterclockwise direction about the circumference of pipe  10 . Likewise, alignment mechanism  120  may adjust the orientation of wheels  110  to the right to guide robotic apparatus  100  along a helical path with coils moving in a clockwise direction about the circumference of pipe  10 . 
     Alignment mechanisms  120 , in various embodiments, may also adjust the orientation of wheels  110  to any suitable degree to control a pitch of the resulting helical path. For example, adjusting the orientation of wheels  110  to the left or right by a small amount (e.g., 5 degrees) may cause the resulting helical pathway to have a large pitch (i.e., large distance between adjacent coils), while adjusting the orientation of wheels  110  to the left or right by a large amount (e.g., 30 degrees) may cause the resulting helical pathway to have a small pitch (i.e., small distance between adjacent coils). Alignment mechanism  120 , in various embodiments, may be configured to adjust the orientation of wheels  110  by up to 89 degrees relative to a longitudinal axis of pipe  10  and still follow a helical pattern; however, alignment mechanism  120  may more preferably be configured to adjust the orientation of wheels  110  from center by between about 1 degree and about 60 degrees. The greater the angle to which the wheels  110  are turned, the further apart the contact areas move on the wheel surface  112 . In other words, if the wheel  110  is to stay in contact with the pipe  10  (and not only contact along the outer rims of the wheels  110 ) the total width of the wheel  110 , the and the diameter of the pipe  10  put an upper limit on the angle to which the wheel  110  can be turned. 
     Referring now to  FIG. 9A ,  FIG. 9B ,  FIG. 9C ,  FIG. 9D ,  FIG. 9E ,  FIG. 9F ,  FIG. 9G ,  FIG. 9H ,  FIG. 10A ,  FIG. 10B ,  FIG. 10C ,  FIG. 11A ,  FIG. 11B ,  FIG. 11C ,  FIG. 11D ,  FIG. 12A ,  FIG. 12B ,  FIG. 12C , and  FIG. 12D , robotic apparatus  100 , in various embodiments, may be repositioned about the circumference of pipe  10  to navigate past various obstacles, as described in more detail below. 
       FIG. 9A ,  FIG. 9B ,  FIG. 9C ,  FIG. 9D ,  FIG. 9E ,  FIG. 9F ,  FIG. 9G , and  FIG. 9H  illustrate a representative approach for navigating a large unidirectional protrusion from pipe  10  such as pipe junctions and pipe supports using robotic apparatus  100 . In  FIG. 9A  robotic apparatus  100  approached a large protruding obstacle. Its orientation is not suitable to pass the obstacle and it will go through the procedure to rotate to a suitable orientation for passing the obstacle. In  FIG. 9B  the robot has turned its wheels in place (to about 45 degrees) using the alignment mechanism that was described earlier in this disclosure. It turns the wheels so that it can commence the helical movement needed to change its orientation with respect to the pipe. In  FIG. 9C  it is starting to travel in a helical pathway along the pipe with the wheels kept at the same angle as in  FIG. 9B .  FIG. 9D  shows the robot as it keeps driving in a helical pathway. It drives along the longitudinal axis and around the circumference of the pipe at the same time. In  FIG. 9E  the robot has reach the preferred orientation with respect to the obstacle. The open side of the robot is on the same side of the pipe as the obstacle.  FIG. 9F  shows how the robot employs the alignment mechanism to turn the wheels back to the default position, where the direction of travel is parallel with the longitudinal axis of the pipe. Once it is in the preferred orientation the robot keeps driving straight to pass the obstacle.  FIG. 9G  shows the robot as it starts to pass the obstacle and the obstacle protrudes through the open side of the robot.  FIG. 9H  shows how the robot has passed the obstacle and it returns to its normal operation. 
       FIG. 10A ,  FIG. 10B , and  FIG. 10C  depict various views of a mechanism  160  for preventing robotic apparatus  100  from falling off of pipe  10  should robotic apparatus  100  decoupled from pipe  10 . Also referred to herein as a “fail-safe mechanism”, mechanism  160  may extend from one or more of wheel assemblies  101  and across open side  102  of robotic apparatus  100 , such that robotic apparatus  100  effectively surrounds pipe  10  on all sides as shown in  FIG. 11A ,  FIG. 11B ,  FIG. 11C , and  FIG. 11D . As configured, should wheels  110  slip or otherwise disengage from pipe  10 , robotic apparatus  100  will remain connected to pipe  10  in a manner that prevents it from falling to the ground and being damaged or destroyed. 
     Referring first to  FIG. 10A , mechanism  160  may generally comprise an arm member  162  and a rotating joint  164 . In various embodiments, rotating joint  164  forms a proximal portion of fail-safe mechanism  160 , and is coupled to or forms part of wheel assembly  101 . Arm member  162  may be coupled to or be integrally formed as part of rotating joint  164 , and may extend across open side  102  of robotic apparatus  100  in a neutral state. To allow for a large protrusion or other obstacle to pass through open side  102  of robotic apparatus  100 , rotating joint  164  may be configured to rotate within the plane of open side  102  in response to forces applied to arm member  162  by the obstacle as robotic apparatus traverses a corresponding section of pipe  10 . Stated otherwise, upon coming into contact with the obstacle, arm member  162  may passively sweep rearwards about a pivot point defined by rotating joint  164  until the obstacle has passed beyond the reach of arm member  162 , as shown in  FIG. 10B . Upon clearing the obstacle, arm member  162  may automatically sweep forward to return to the neutral state, where it again extends across open side  102  to prevent robotic apparatus  100  from falling should wheels  110  decouple from pipe  10 . 
     To that end, rotating joint  164 , in various embodiments, may include a biasing mechanism  166 , such as torsion spring or other mechanism/assembly configured to apply a restorative force for returning arm member  162  to the neutral state after an obstacle is passed. In the embodiment shown in  FIG. 10C , biasing mechanism  166  includes an assembly of linear springs  167   a,    167   b  connected to a pulley assembly  168 . In particular, springs  167   a,    167   b  may be the same or substantially similar to one another, and may be arranged side-by-side and extend from a proximal end of fail-safe mechanism  160  towards pulley assembly  168 . Pulley assembly  168  may include a pulley connected to springs  167   a,    167   b  by a cable, wire, string, or other such connector (collectively, “cable” hereinafter). A first end  168   a  of the cable may extend axially through spring  167   a  and connect to a cap  169   a  positioned at a proximal end of spring  167   a,  and likewise a second end  168   b  of the cable may extend axially through spring  167   b  and connect to a cap  169   b  positioned at a proximal end of spring  167   b.  As configured, when arm member  162  (and by extension pulley  169 ), is swept clockwise this figure, pulley assembly  168  may pull cable end  168   b  (and attached cap  169   b  ) downwards, thereby progressively compressing spring  167   b.  This in turn builds up a restoring force in spring  167   b  that generates a counterclockwise moment for sweeping arm member  162  counterclockwise in this figure back to the neutral state when the obstacle has cleared arm member  162 . Likewise, when arm member  162  (and by extension pulley assembly  168 ), is swept counterclockwise in this figure, pulley assembly  168  may pull cable end  168   a  (and attached cap  169   a ) downwards, thereby progressively compressing spring  167   a.  This in turn builds up a restoring force in spring  167   a  that generates a clockwise moment for sweeping arm member  162  clockwise in this figure back to the neutral state when the obstacle has cleared arm member  162 . 
     Notably, rotating joint  164 , in various embodiments, may be constrained to rotation within the plane of open side  102  only, and thus not permitted to rotate transverse to (e.g., away from or towards pipe  10 ) said plane, such that fail-safe mechanism  160  does not permit pipe  10  to pass through open side  102  in the event robotic apparatus  100  were to decouple from pipe  10 . 
       FIG. 11A ,  FIG. 11B ,  FIG. 11C , and  FIG. 11D  illustrate a representative approach for navigating a large unidirectional protrusion from pipe  10  such as pipe junctions and pipe supports when robotic apparatus  100  is equipped with fail-safe mechanism  160 .  FIG. 11A  shows robotic apparatus  100  as it approaches an obstacle protruding from pipe  10 . In this figure, robotic apparatus  100  is already in the preferred orientation for passing the protruding obstacle—that is, open side  102  is aligned with the protruding obstacle. It drives straight ahead, parallel to the longitudinal axis of the pipe. In  FIG. 11B , robotic apparatus  100  starts to pass the obstacle and the failsafe mechanism  160   a  attached to the first wheel assembly has hit the protrusion. Since arm member  162  is free to rotate in this plane it starts to pivot as it gets pushed by the protruding obstacle. In  FIG. 11C , the first failsafe mechanism  160  has completely passed the obstacle and biasing member  166  has returned arm member  162  to its neutral state. The middle failsafe mechanism  160   b  is now passing the protruding obstacle.  FIG. 11D  shows how the middle failsafe mechanism  160   b  has cleared the obstacle and returned to its neutral position. The last failsafe mechanism  160   c  is now contacting the protruding obstacle. Once the last wheel assembly passes the obstacle the last failsafe mechanism  160   c  will swing back to the neutral safe position and robotic apparatus  100  is free to return to its normal operation. 
       FIG. 12A ,  FIG. 12B ,  FIG. 12C , and  FIG. 12D  illustrate a representative approach for navigating a bend or curve in pipe  10  using robotic apparatus  100 .  FIG. 12A  shows the ideal orientation of the robotic apparatus  100  as it approaches the bend. The depicted embodiment of robotic apparatus  100  is designed to traverse the bend with the single wheel assembly  101   a  driving along the outer centerline of the bend and the two wheel assemblies  101   b,    101   c  on the opposing side to drive along the inner centerline of the bend. Alternative embodiments have been designed so that the single wheel assembly  101   a  can drive along the inside of the bend and the two wheel assemblies  101   b,    101   c  can drive along the outside of the bend. However, these two different approaches place different constraints on the range of motion of the clamping mechanism  150 , and a single embodiment is typically designed to employ one of the two approaches.  FIG. 12B  shows how the robotic apparatus  100  enters the bend. As shown, robotic apparatus  100  has to expand significantly as it drives towards the apex of the bend. The outside wheel in wheel assembly  101   a  will speed up as it enters the bend to compensate for the longer path length compared to the other wheels. In  FIG. 12C , robotic apparatus  100  has passed the apex of the bend. At this stage clamping mechanism  150  gradually contracts to keep the wheels  110  in contact with the surface of the pipe  10  and the outside wheel  110   a  gradually returns to the same speed as the other wheels  110   b,    110   c,  as the path length difference diminishes. In  FIG. 12D , robotic apparatus  100  has completely passed the bend and it returns to its normal operation. 
     Pipeline Inspection and Other Payloads 
       FIG. 13A  and  FIG. 13B  illustrate an embodiment of robotic apparatus  100  including a sensor assembly  170  for performing structural inspections of pipe  10 . Sensor assembly  170 , in various embodiments, may generally include one or more arms  172  and an actuator  174  for positioning a sensor  176  relative to pipe  10 . 
     Sensor  176 , in various embodiments, may include one of a variety of sensors suitable for inspecting or otherwise gathering information concerning pipe  10  and/or the surrounding environment. For example, in an embodiment, sensor  176  may include an ultrasonic sensor or other sensor suitable for non-destructive inspection (NDI) of structural aspects of pipe  10 , such as measuring wall thickness or detecting cracks/corrosion. In another embodiment, sensor  176  may include a sensor configured to sample air proximate to pipe  10  for traces of fluids (e.g., natural gas, oil) that may have leaked out of pipe  10 . Such traces may be indicative of cracks or corrosion in pipe  10 , and thus may be used for structural inspection purposes. While sensor assembly  170  of the present disclosure may be described in the context of positioning a sensor  176  for pipeline inspection purposes, it should be recognized that any sensor  170  may be used in connection with sensor assembly  170  for any suitable purpose. 
     Arm(s)  172 , in various embodiments, may couple sensor  176  to robotic apparatus  100  and be moved to position sensor  176  relative to pipe  10 . In particular, a first end of arm(s)  172  may be rotatably coupled to robotic apparatus  100 , for example, on strut  156  as shown. As configured, arm(s)  172  may be pivoted up and down on strut  156  and thereby position sensor  176  away from or close to pipe  10 , respectively. In an embodiment (shown), the second end of arm(s)  172  may also be rotatably coupled to sensor  176 , thereby allowing sensor  176  to pivot relative to arm(s)  172  and thus remain parallel to the surface of pipe  10  if desired or necessary for sensor  176  to function optimally.  FIG. 13A  illustrates sensor assembly  170  in a raised position and  FIG. 13B  illustrates sensor assembly in a lowered position. Arm(s)  172 , in an embodiment, may be used to raise sensor  176  to a position away from pipe  10  when measurements are not needed and/or to prevent sensor  176  from colliding with an obstacle along pipe  10 . Conversely, arm(s)  172 , in an embodiment, may be used to lower sensor  176  to a position close to or against pipe  10  for taking measurements. 
     Actuator  174 , in various embodiments, may be used to move arm(s)  172  in positioning sensor  176 . Actuator  174  may include any actuator, motor, and associated assemblies (e.g., pulleys, gear trains). In the exemplary embodiment shown, actuator  174  includes a linear actuator having a proximal end rotatably coupled to wheel assembly  101   a  of robotic apparatus  100  and having a distal end coupled to arm(s)  172 , and specifically here to a cross-bar member extending between arms  172  that freely rotates to maintain alignment with linear actuator  172 , as shown, regardless of whether linear actuator  172  is in an extended or retracted position. Of course, one of ordinary skill in the art will recognize alternative actuators that may be suitable for the described purpose within the scope of the present disclosure. For example, in another embodiment (not shown), actuator  174  may include a motor configured to wind in/out a cable or pulley assembly positioning arm(s)  172  and sensor  176  coupled thereto. 
       FIG. 14A ,  FIG. 14B ,  FIG. 14C , and  FIG. 14D  depict another embodiment of sensor assembly  170 , which generally includes sensor  176 , and an articulated arm  190  comprising a first arm segment  192  and a second arm segment  194 . A proximal end of first arm segment  192  may be rotatably coupled by a first rotating joint  193  to robotic apparatus  100  such that articulated arm  190  may be rotated relative to robotic apparatus  100 . A proximal end of second arm segment  194  may be rotatably coupled by a second rotating joint  195  to a distal end of first arm segment  192  such that second arm segment  194  may be rotated relative to first arm segment  192 . Each rotating joint  193 ,  195 , in various embodiments, may be motorized and configured for independent rotation from one another. As configured, first rotating joint  193  may raise or lower articulated arm  190  relative to pipe  10  and second rotating joint  195  may independently adjust an orientation of sensor  176  relative to the surface of pipe  10 , as shown in  FIG. 14A  and  FIG. 14C . 
     Further, first rotating joint  193  may be rotated to a greater extent for positioning articulated arm  190  out in front of either end of robotic apparatus  100 , as shown in  FIG. 14B  and  FIG. 14D . As configured, sensor  176  may be positioned to take measurements in front of robotic apparatus  100  regardless of its direction of travel on pipe  10 . In one aspect, this configuration may provide for more accurate measurements, as robotic apparatus  100  would not yet be in contact with the portion of pipe  10  being inspected with sensor  176 , which may otherwise produce vibrations, cause a dampening effect, or otherwise affect structural properties of the portion of pipe  10  being inspected. In another aspect, by positioning sensor assembly out in front of robotic apparatus  100  (again, regardless of the direction of travel), it may be possible to inspect portions of pipe  10  all the way up to an upcoming obstacle. Contrast this with only being able to inspect only those portions of pipe  10  more than a length of robotic apparatus away from the upcoming obstacle because sensor assembly  170  is positioned behind robotic apparatus  100 . 
       FIG. 20 ,  FIG. 21 ,  FIG. 22 ,  FIG. 23 , and  FIG. 24  are photographs of a prototype of a representative embodiment of robotic apparatus  100  for further illustrative purposes.  FIGS. 20 and 21  depict side views of the prototype of robotic apparatus  100 , with wheels  110  aligned for straight travel along pipe  10 .  FIG. 22  depicts a bottom view of the prototype of robotic apparatus  100 , with the orientation of wheels  110  adjusted for helical travel along pipe  10 .  FIG. 23  depicts a side view of the prototype of robotic apparatus  100  navigating a bend in pipe  10 .  FIG. 24  depicts a side view of the prototype of robotic apparatus  100 , with open side  102  positioned for passing an obstacle protruding from pipe  10 . 
     Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.