Patent Publication Number: US-2021190252-A1

Title: Two-wheeled pipe crawler

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/949,955, filed on 18 Dec. 2019. The co-pending Provisional Patent Application is hereby incorporated by reference herein in its entirety and is made a part hereof, including but not limited to those portions which specifically appear hereinafter. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention is related to an untethered self-powered two-wheeled pipe crawler. 
     Background 
     Internal inspection, maintenance and repair of underground pipelines typically involves expensive excavation of the ground surrounding the pipeline. Excavation is at once expensive, time consuming and risks additional damage to the pipeline. 
     Alternatively, internal pipeline inspection tools are available that may be dropped into a pipeline, typically with a tether or similar leash. Such internal inspection tools, sometimes referred to as “pigs,” are typically cumbersome, expensive and have limited mobility within most pipelines. 
     Tools for internal pipeline inspection include those for geometric surveys of pipeline infrastructure and layout; detection of cracks or leaks; location of blockages or debris within the pipeline; and/or other functions particularly suited to the mapping, imaging and/or repair of a pipeline system. 
     Some previous untethered crawlers include Louis, U.S. Pat. No. 7,343,863 directed to a self-righting, bi-directional pipe crawler; Louis, U.S. Pat. No. 8,205,559 directed to a self-righting, two-wheeled pipe crawler; and Louis, U.S. Pat. No. 8,464,642 directed to a self-orienting, two-wheeled pipe crawler, which are each incorporated by reference herein. 
     SUMMARY OF THE INVENTION 
     A preferred embodiment of the invention describes an untethered crawler for use within a pipeline. The crawler preferably comprises a body; a pair of wheels that are positionable between a retracted and a deployed position; and a multi-axis control unit for controlling axial motion, yaw, pitch and roll of the crawler within the pipeline. Such a device may be better understood with the following drawings and detailed description of preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows roll as traditionally used in aviation; 
         FIG. 1B  shows pitch as traditionally used in aviation; 
         FIG. 1C  shows yaw as traditionally used in aviation; 
         FIG. 2A  shows a crawler in a retracted position, according to one embodiment; 
         FIG. 2B  shows the crawler of  FIG. 2A  transitioning from the retracted position to a deployed position, according to one embodiment; 
         FIG. 2C  shows the crawler of  FIG. 2B  transitioned to the deployed position, according to one embodiment; 
         FIG. 3  shows an exploded front perspective view of a crawler according to one embodiment; 
         FIG. 4  shows an exploded front view of the crawler shown in  FIG. 3 ; 
         FIG. 5  shows a front perspective view of a crawler with wheels in a retracted position, according to one embodiment; 
         FIG. 6  shows a front view of the crawler shown in  FIG. 5 ; 
         FIG. 7  shows a front perspective view of a crawler with wheels in a deployed position, according to one embodiment; 
         FIG. 8  shows a front view of the crawler shown in  FIG. 7 ; 
         FIG. 9  shows a front perspective view of the crawler shown in  FIG. 5  with wheels exhibiting roll control, according to one embodiment; 
         FIG. 10  shows a top view of the crawler shown in  FIG. 9  including measurements for calculating a deployment axis; 
         FIG. 11  shows calculations in accordance with  FIG. 10 ; 
         FIG. 12A  shows a deployment sequence starting with orientation of the crawler; 
         FIG. 12B  shows a deployment sequence starting from a position of the crawler shown in  FIG. 12A  where the wheels are starting deployment; 
         FIG. 12C  shows a deployment sequence from  FIG. 12A  where the wheels are driven while unfolding; 
         FIG. 12D  shows a deployment sequence from  FIG. 12A  where the wheels are fully deployed at the calculated angle of the elliptical plane calculated in  FIGS. 10 and 11 ; 
         FIG. 13A  shows a front schematic view of a crawler beginning a roll sequence according to one embodiment; 
         FIG. 13B  shows a front schematic view of the crawler of  FIG. 13A  with angled wheels relative to one another to initiate the roll sequence; 
         FIG. 13C  shows a front schematic view of the crawler of  FIG. 13A  with compensated angled wheels relative to one another to continue the roll sequence; 
         FIG. 14  shows a cutaway view inside a pipeline with the crawler in a roll; 
         FIG. 15  shows a partially exploded perspective view of a crawler with a flywheel according to one embodiment; 
         FIG. 16A  shows a cutaway view inside a pipeline with a crawler in a configuration prior to turning a corner; 
         FIG. 16B  shows the pipeline of  FIG. 16A  after the crawler turns the corner; 
         FIG. 17  shows a perspective view of a crawler with sensors and measurable variables according to one embodiment; 
         FIG. 18  shows a cutaway view inside a pipeline with a crawler demonstrating axial translation, according to one embodiment; 
         FIG. 19  shows a cutaway view inside a pipeline with a crawler demonstrating yaw control, according to one embodiment; 
         FIG. 20  shows a schematic view of a pipeline and hot tap, according to one embodiment; and 
         FIG. 21  shows a crawler following insertion through a hot tap, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to a preferred embodiment of the subject invention, a two-wheeled pipe crawler is disclosed which permits long-term flexible use within a pipeline with minimal maintenance and maximum mobility within a range of pipe sizes and configurations. The crawler disclosed herein, known as Gas Technology Institute&#39;s PIPERIDER crawler, includes configurations disclosed in embodiments shown in  FIGS. 1-21 . 
       FIG. 1A-C  show schematically roll, pitch, and yaw, respectively, which are common rotational axis names from the aviation industry. Roll describes rotational movement about the X axis (the direction of travel) and is shown in  FIG. 1A .  FIG. 1B  shows pitch which is the rotational movement about the Y axis, perpendicular to and horizontally aligned relative the direction of travel.  FIG. 1C  shows yaw which is the rotational movement about the Z axis, perpendicular to and vertically aligned relative to the direction of travel. Although “horizontal” and “vertical” are generally used herein, these terms are relative and depend on the relative orientation of the crawler  10 . The axes are intended to be local and moveable depending on orientation. 
       FIGS. 2A-C  show schematically a crawler  10  of the subject invention, as further described below, transitioning between a retracted position in  FIG. 2A , an intermediate position in  FIG. 2B  and a deployed position in  FIG. 2C . The crawler  10  according to this invention is likewise capable of roll, pitch, and yaw controls as further described. 
       FIGS. 3-8  show some basic views of the crawler  10 , in preferred embodiments of the subject invention, in exploded views at  FIGS. 3 and 4 , in the retracted position in  FIGS. 5 and 6 , and in the deployed position in  FIGS. 7 and 8 . The crawler  10  preferably includes two wheels  20 , wherein one wheel  20  is positioned on each side of a body  30 . The body  30  preferably further includes rotatable gimbals between the wheels  20  and the body  30  and one or more motors  50 ,  60 ,  70 ,  80 , described in more detail below. 
     As best shown in  FIGS. 5 and 6 , the wheels  20  are preferably upright relative to the body  30  in a retracted position. The crawler  10  in the retracted position preferably includes wheels  20  that are parallel with respect to each other. Although not optimized for travel in this position, the crawler  10  is capable of maneuvering and movement while in this retracted position. 
     As best shown in  FIGS. 7 and 8 , the wheels preferably extend outwardly in a deployed position. In the deployed position, the wheels  20  are preferably aligned in a single plane for travel in a straight direction. Internal motors  60  described in more detail below may be used to move the wheels  20  between the retracted position and the deployed position. The crawler  10  is preferably moveably operable in both the retracted and deployed positions of the wheels  20 , however, in the deployed position, movement and maneuverability is optimized. 
     In the retracted position, the wheels  20  are parallel with respect to each other forming a more compact unit which may assist in inserting the crawler  10  into a pipeline, such as a pipe entry via a hot tap  150  as shown in  FIGS. 20 and 21 . Traditionally, existing crawlers require placement into a pipeline through a riser pipe because of their size. However, the crawler  10  according to subject invention may alternatively be placed into smaller and more convenient hot taps  150 . As such, the crawler  10  includes body  30  and wheels  20  that are dimensioned to fit within a keyhole of a hot tap  150  when in the retracted position. The crawler  10  is configured to safely land on the bottom of a gas pipeline through the hot tap  150 . Once inserted into a pipeline in the retracted position, the crawler  10  may then be placed into the deployed position for operation. 
     The crawler  10  may be deployed by driving tires in opposite directions while unfolding them and, once deployed, the crawler  10  may move axially through the pipeline such as shown in  FIG. 12C . In such axial motion, the crawler  10  is preferably elevated off the bottom of the pipeline. In this manner, the crawler  10  can avoid detritus that may be present along a bottom surface of the pipeline. 
     Sizing of the crawler  10  may be accomplished with the following calculations as indicated in  FIG. 10 . Using SI units, a tire radius  25  is subtracted from a pipe radius  145  (b) to determine a body radius  35  (a). The major axis of the bottom half of an elliptical tire path (c) can be determined with the Pythagorean theorem. Then the radian angle of the elliptical tire path is the arctan of the body radius  35  divided by the pipe radius  145 : 
     For example, for a PipeRadius  145  of 125 mm (b) minus a TireRadius  25  of 22 mm=a BodyRadius  35  of 103 mm (a). The major axis of the ellipse (c) is square root (BodyRadius{circumflex over ( )}2+PipeRadius{circumflex over ( )}2)=162 mm. The plane of the ellipse is at an angle from vertical=arctan (BodyRadius/PipeRadius)=0.6892 radians. This is also 39.5 degrees. 
     As best shown in  FIGS. 12A-D , in one embodiment of this crawler  10 , while laying at the bottom of the pipeline  140  after entry from the hot tap  150  or riser pipe, deployment is a preferably a 4-step process: (1) orientation to an upright position with wheels  20  still retracted using only translation motors  80  such as shown in  FIG. 12A ; (2) pre-deployment of the wheel gimbals  40  using both translation motors  80  and roll motors  70  simultaneously to inclination angle of elliptical path while tire remains motionless, as described above, and shown in  FIG. 12B ; (3) deployment using both translation motors  80  and deploy-retract motors  60  simultaneously while unfolding the wheels  20 , as shown in  FIG. 12C ; and (4) post-deploy to return both wheels to a common plane as shown in  FIG. 12D  and  FIG. 8  using roll motor  70  only to return wheel  20  from the inclination angle to the x-y plane. Specifically, deployment preferably involves simultaneously rotating the wheels  20  in opposite directions to climb a sidewall of the pipeline and then unfolding the wheels  20  to a coplanar orientation. 
     According to one embodiment, the body  30  may include a partitioned center section that is expandable or contractable using a spring or a rack. In this manner, the crawler  10  may include an onboard coarse adjustment to adapt the crawler  10  for different pipe sizes. Alternatively, the wheels  20  and/or gimbals  40  may be sized according to the calculations above to adapt to a particular pipe diameter. Based on the operation as described herein, however, the crawler  10  may function within a reasonable range of pipe sizes based on the dynamics of the crawler  10  in the deployed position. 
     In a preferred embodiment of the invention, the plant dynamics of the pipe crawler  10  are modeled as two mobile inverted pendulums. Using this model, a multi-axis control unit  100  is positioned within the body  30  of the crawler  10  to control a roll, pitch, and yaw within the pipeline. 
     According to a preferred embodiment, the multi-axis control unit  100  is capable of controlling not only roll and yaw but pitch of the crawler  10 , as well. In this way, the crawler  10  is capable of movement around hard corners such as shown in  FIG. 16A and 16B . Ideally, the crawler  10  as described can move horizontally or vertically through the pipeline. 
     In order to affect such pitch control, the crawler  10  may further include a spinning mass located within the body  30  of the crawler  10 , as shown in  FIG. 15 . More specifically, this spinning mass may comprise an internal flywheel  45 . The internal flywheel  45  or similar spinning mass preferably spins on an axis perpendicular to a rotational axis of the wheels to control the pitch of the crawler  10 . The multi-axis control unit  100  is preferably adapted to adjust a speed of the flywheel  45  within the body of the crawler  10  to control pitch thereby allowing the crawler  10  to turn a corner. 
     Per the aviation terminology described above, pitch is rotation about the y axis. The equation is from Kinetics Impulse-Momentum and is known as the Conservation of Angular Momentum equals Mass Moment of Inertia times the Angular Velocity of the spinning mass. When the spinning flywheel  45  is stopped by the control unit  100 , momentum of the flywheel  45  is transferred to the crawler body  30 , thus changing the pitch of the crawler  10 . 
     As described above, the crawler  10  preferably includes one or more motors to provide the intended motion and maneuverability. In one preferred embodiment, the crawler includes seven motors on or within the body. A pitch motor  50  is preferably positioned within the body  30  to activate, operate and maintain the flywheel  45  or similar spinning mass or reaction wheel. 
     A deploy-retract motor  60  is preferably positioned with respect to each wheel  20  and gimbal  40  such as shown schematically in  FIGS. 3 and 4 . Likewise, a roll motor  70  is preferably positioned with respect to each wheel  20  to adjust the angle of the tire gimbals  40 . In addition, a translation motor  80  is preferably positioned with respect to each wheel  20  as shown in  FIGS. 3 and 4  to impart forward and reverse motion to the wheels  20 . 
     To facilitate control of the crawler, particularly pitch and yaw control, the multi-axis control unit  100  preferably receives distance measurement data from one or more onboard sensors  110  to control yaw and pitch of the crawler  10  within the pipeline.  FIG. 17  demonstrates one embodiment of such distance measurements. Preferably these measurements are taken and processed in real time to constantly adjust and maintain control of the crawler  10  as it proceeds through a pipeline. As shown in  FIG. 17 , at least two measurements are preferably taken in each of the vertical (Z) for yaw and horizontal (Y) for pitch in order to maintain and correct the movement of the crawler  10 . 
     Using  FIG. 17  as an illustration, on each respective yaw or pitch plane, the difference of the average of two opposing sensors results in the error used by the control unit  100  in real time to align a centerline of the crawler  10  with a centerline of the pipe. In fact, such measurements and feedback preferably occur many times per second to maintain the course and travel of the crawler  10 . 
     The multi-axis control unit  100  preferably comprises a closed loop position control algorithm to allow the 4 degrees of freedom motion. A high-speed processor further enables the feedback loop necessary to maintain the crawler  10 . 
     As described above, the distance sensors  110  are preferably located in at least the vertical and horizontal direction and preferably include two such sensors  110  in each direction. Preferable sensors  110  may include structured light cameras or LIDAR positioned with respect to the body. The multi-axis control unit  100  is preferably configured to adjust the speed of each wheel  20  independently based on feedback from the one or more sensors  110  for yaw control as the crawler  10  proceeds through the pipeline. 
     As shown in  FIGS. 16A and 16B , the pitch angle of the crawler  10  may be controlled so it can turn a corner (pitch control). As shown, one or more onboard sensors  110  may detect that no sidewall is present at a junction of the pipeline and the crawler  10  may then back-up and realign vertically as shown in  FIG. 16A  before turning the corner as shown in  FIG. 16B . The crawler may then realign again to a horizontal configuration to move axially as shown in the top views of  FIGS. 17-19 . 
       FIG. 19  shows the crawler  10  in a deployed position relative to the walls of a gas pipeline (yaw control). The arrows represent distance measurements preferably taken in realtime by the onboard sensors  110  of the crawler. In one embodiment, four sensors  110  are positioned on the body  30  such that a fore and aft sensor  110  are positioned on each transverse side of the body  30 . In this way, measurements to the sidewall are compared on each side of the body  30  and when the measurements are equal on each side of the crawler, equilibrium and thus yaw control is obtained within the pipeline. As described, sensors  110  may be four distance sensors as described above or may include any one or more single sensor or array of sensors capable of measuring distance to the sidewall of the pipe. Such sensors may include camera-based sensors, structured light sensors, laser measurement devices, LIDAR, infrared light, ultrasonic sound distance sensors, and LIDAR time of flight sensors, photoelectric sensors or any other suitable device for fast and accurate measurement of a distance between a position on or near the body  30  and the pipe sidewall. 
     The crawler  10  may further include a rechargeable battery  120 , such as shown schematically in  FIG. 18 . The rechargeable battery  120  may be nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), Lithium Iron Phosphate (LiFePO4), lithium-ion polymer (Li-ion polymer), or other suitable compact battery composition capable of long battery life and short recharging durations. The rechargeable battery  120  may be chargeable using inductive charging and the pipeline may include one or more inductive charging stations  125 , also shown schematically in  FIG. 18 . In this manner, the crawler  10  may be recharged without any contact between the crawler  10  and the charging station  125  which is ideal in a pipeline environment. A virtual infinite range may be provided to the crawler  10  through a series of such charging stations  125 . This allows the crawler  10  to be established semi-permanently within a given pipeline by including a means or system for recharging onboard batteries. 
     Alternatively, the crawler  10  and/or rechargeable battery  120  may be charged or powered using an internal generator for generating electrical power from a gas flowing within the pipeline. A turbine or similar generator may be positioned on the crawler  10  to generate a charge from the flow of gas within the pipeline, such as natural gas. In this way, energy may be harvested from inside a live natural gas pipeline to charge the battery. 
     The crawler  10  may further include a camera  160 , such as shown in schematically in  FIG. 19 . The camera  160  may operate as a sensor  110  described above or may be alternatively or additionally positioned to accommodate visual inspection of the pipeline. 
     A corresponding method of operation of an untethered crawler  10  for use within a pipeline includes: providing the crawler  10  having a body  30  and pair of wheels  20  that are positionable between a retracted and a deployed position; positioning the wheels  20  in the retracted position and inserting the crawler  10  into a pipeline; moving the wheels  20  into the deployed position, preferably along gimbals  40 ; and controlling the yaw, roll, and pitch of the crawler using a multi-axis control unit. The crawler  10  as described is preferably operable in both the retracted and the deployed position. 
     As partially described above, the crawler is preferably capable of one or more work functions that were previously unavailable for remote devices. To accomplish one or more of these tasks, an additional payload  170  may be necessary for placement on or within the crawler. The payload  170  is shown schematically in  FIG. 18 . Such payload  170  may be integrated with the body  30  or may be positioned on the body  30  or the wheels  20  depending on the desired functionality. 
     One object of the crawler  10  as described is to transport interchangeable inspection and repair payloads. Such payloads may include locational and/or mapping devices, repair devices, inspection devices and/or other similar payloads which may be required in a pipeline environment. 
     In environments where a wireless signal may be difficult to obtain or maintain within a pipeline, a surface slave vehicle  180  may be used to “chase” the crawler from above ground or outside of the pipeline and to relay signals to and/or from the crawler, such as shown schematically in  FIG. 20 . The slave vehicle  180  may comprise an aerial drone, an autonomous vehicle or even a human operator following a signal transmitted to the surface. 
     According to one embodiment, the payload  170  may comprise a microphone array positioned relative to the crawler to triangulate and orient around a gas leak such that an epoxy syringe or similar repair device can repair a gas leak from inside a pipe. As such, an additional payload  170  may include an epoxy gun or similar repair device for urging a curable composition into a leak in the pipeline. 
     According to another embodiment, an inertial measurement unit may be used on the crawler to record location data of a pipeline. Such location data may be assembled to generate a highly accurate map of the entire pipeline system. Alternatively, or in addition, the crawler  10  may include a tire encoder in communication with the multi-axis control unit  100  to obtain data for mapping pipelines. 
     If necessary, the crawler  10  may be removed entirely from the pipeline through a magnetic retrieval tether. The wheels  20  may be retracted or partially retracted in order to facilitate removal from a removal station, a hot tap or any other similar station for removing the crawler  10 . 
     While in the foregoing detailed description the subject development has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the subject development is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.