Abstract:
The specification discloses a robot for inspection adapted to travel virtually unlimited distances through small-diameter enclosed spaces such as conduits or ducts, preferably using a fluid-driven screw-drive propulsion system. The robot preferably includes a drive module having a plurality of wheels inclined at an angle greater than zero degrees and less than ninety degrees to the longitudinal axis of the pipe, a driver module having a plurality of wheels aligned parallel to the longitudinal axis of the pipe, and a power module. The driver module is preferably connected to the drive module such that the drive and driver modules are capable of providing the locomotive motion of the robot. The power module preferably provides the power to the drive and driver modules.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 60/329,862, filed Oct. 17, 2001, which is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a robotic apparatus and, more particularly, to a robotic apparatus adapted to travel through enclosed spaces such as conduits or ducts using mechanically enabled helical-like motions. 
     2. Background of Relevant Art 
     Pipe crawlers, pipe inspection pigs and similar vehicles are widely used for inspecting the interior surfaces of piping systems, storage tanks, and process vessels for damaged or flawed structural features. Typically, such devices include a testing probe, sensor, or camera carried by a support structure that travels through the piping system being inspected. 
     Many of the remote inspection devices have been designed for pipes having a six-inch or greater inner diameter. However, there remains a need for the inspection of smaller diameter pipes, such as coiled steel tubing. In particular, there is a need for small-diameter inspection devices that are capable of travelling very long distances. For example, coiled steel tubing is often produced with lengths of 7,620 m (25,000 ft) at 32 mm (1.25 in) diameter or 1,800 m (6,000 ft) at 90 mm (3.5 in) diameter. Lengths of coiled tubing are stored on reels with diameters from 2 ft to 20 ft. 
     While current advances in miniaturization technology have made cameras and sensors small enough to fit within a small diameter pipe, there have been few advances in the design of a crawling apparatus having adequate motive forces to deploy a small diameter inspection apparatus through an extensive pipe system. For example, miniature electric motors do not provide enough motive force to pull extensive length tethers behind the crawler. Similarly, miniature air cylinders do not have the capacity to generate enough pushing force directly against the inner-walled pipe as is required for inch-worm motion. In addition, neither technology is capable of propelling an inspection devices of the mile-plus distances that may be required. 
     The art teaches a variety of larger-diameter pipe inspection apparatuses. One such apparatus is taught in U.S. Pat. No. 4,006,359 to Sullins et al. The crawler of Sullins et al. is a completely self-contained, self-propelled and self-operated vehicle adapted to travel through a pipeline, stop at particular locations such as a girth weld between adjoining sections of pipe, inspect the weld, for example by X-raying it and then proceed onto the next location to be inspected. While suitable for use in large diameter pipelines and traveling short distances, the crawler of Sullins et al. would not be feasible for use in coiled tubing for the following reasons. First, Sullins et al&#39;s crawler includes x-ray equipment (e.g. x-ray tube), which has not yet been fabricated to fit in small pipe diameters. Secondly, because x-ray equipment requires a large amount of power to operate, the size of the power source is dependent on the x-ray equipment, and thus greatly increased. Therefore, in addition to the x-ray equipment, the size of the power source may prohibit the crawler from traveling in small diameter spaces for long distances. 
     Another such apparatus is taught in U.S. Pat. No. 5,392,715 to Pelrine. Pelrine teaches an in-pipe running robot which does not easily turn over even when running round circumferentially inside piping. Still another such apparatus is taught in U.S. Pat. No. 4,862,808 to Hedgcoxe et al. Hedgcoxe et al. describes a robotic pipe crawling device having module pivot flexibility, which enables the device to negotiate corners with complete autonomy. However, there are limitations to the size and motive force capable of being exerted by these prior art devices as set forth above. 
     In particular, there is a need for a pipe inspection apparatus that will provide the necessary motive force for small diameter pipes. The apparatus should be dimensioned to pass through various sizes of piping and be able to readily negotiate bends in the piping. In addition, the pipe crawler should be autonomous and able to generate a sufficient motive force that can propel inspection equipment. Also, the pipe crawler should be capable of traveling in forward and backward directions, accelerating, decelerating, and stopping. 
     Thus, what is needed is a robotic apparatus that overcomes the deficiencies of the currently available technologies. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the prior art by providing a robotic apparatus adapted to travel through enclosed spaces such as conduits or ducts using a mechanical propulsion system. 
     In a preferred embodiment of the present invention, a robot for in-pipe inspection includes a drive module having a plurality of wheels inclined at an angle greater than zero degrees and less than ninety degrees to the longitudinal axis of the pipe, a driver module having a plurality of wheels aligned parallel to the longitudinal axis of the pipe, and a power module. The driver module is preferably connected to the drive module such that the drive and driver modules are capable of providing the locomotive motion of the robot. The power module preferably provides the power to the drive and driver modules. Various sources of power can be used with the present device. Particularly preferred is a turbine system that allows the device to be powered by the a flow of fluid, such as air, through the pipe or conduit. 
     The present device is capable of operating in a autonomous mode, wherein it derives power from the flow of fluid through the conduit and is capable of propelling itself in either the same or opposite direction as the fluid flow and at a speed that may vary from the fluid velocity, and a passive mode, in which the drive mechanism is inactivated and the device is carried by the fluid flow itself. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
         FIG. 1  is a schematic side view of a pipe-crawling robot in accordance with an embodiment of the present invention; 
         FIG. 2  is an end view of the device shown in  FIG. 1 ; 
         FIG. 3  is a schematic side view of a first segment of the robot shown in  FIG. 1 ; 
         FIG. 4  is a schematic side view of a second segment of the robot shown in  FIG. 1 ; 
         FIG. 5  is a block diagram of software architecture in accordance with an embodiment of the present invention; 
         FIG. 6  is a schematic side view of a pipe-crawling robot in accordance with an alternate embodiment of the present invention; and 
         FIG. 7  is a schematic perspective view of one portion of the third segment of the robot shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In order to fully describe the embodiments of the present invention, reference will be made throughout this description to a longitudinal axis. The longitudinal axis is parallel to the axis of symmetry of the conduit or pipe through which the robot is traveling. It should be appreciated that the scope of the invention is only limited by the claims and not by this description. 
     Referring initially to  FIGS. 1 and 2 , the present invention provides a pipe-crawling robot  10 . Robot  10  generally consists of at least two independently modular, articulated segments: first segment  20  and second segment  50 . First segment  20  is preferably connected to second segment  50  by a flexible coupling  75 . Flexible coupling  75  is free to bend about the longitudinal axis of robot  10 , but prevents the relative rotation about the longitudinal axis. The combination of first segment  20  and second segment  50  provide the locomotive motion of robot  10 , as will be described below in detail. 
     Referring now to  FIG. 3 , a more detailed depiction of first segment  20  is shown. First segment  20  preferably includes two end sections  22 ,  24 , and a motor  56  disposed between end sections  22  and  24 . End sections  22 ,  24  may house components such as sensor and tool components (not shown). In a preferred embodiment, a shaft  26  couples motor  56  to end section  24 . Motor  56  is preferably an electric motor, such as a DC servomotor. In a preferred embodiment, shaft  26  engages end section  22  such that a when power is supplied to motor  56 , motor  56  causes relative rotation between end sections  22  and  24 . 
     In addition to housing components, at least one of end sections  22  and  24  serves as a platform for a plurality of pitched wheels  30 , which are each supported on a suspension systems (not shown). Wheels  30  preferably include polymeric tires  32  and possess ball-bearing hubs (not shown). Pitched wheels  30  are preferably inclined at an angle greater than zero degrees and less than ninety degrees with respect to the longitudinal axis, producing at least one helical row of wheels  30  around first segment  20 . The pitch of the wheels may be adjusted so that robot  10  travels at an acceptable speed, dependent on the environment of the conduit it is traveling in. For example, in smooth regions within the conduit, the pitch of the wheels  30  is preferably decreased so that robot  10  travels at a faster pace. Alternatively, in rough regions within the conduit, the pitch of the wheels  30  may be increased so that robot  10  travels at a slower pace. 
     In addition to pitch, the placement and number of wheels  30  may also be varied. In a preferred embodiment, end sections  22 ,  24  each include three wheels  30  located 120° apart from each other. As shown in the embodiment of  FIG. 3 , the wheels  33  on end section  24  are non-pitched. 
     Referring still to  FIG. 3 , the suspension systems are preferably spring-loaded cartridges  38 , which are affixed in recesses  23  in end sections  22 ,  24 . In an alternate embodiment, the suspension systems are cam-driven cartridges (not shown). The cams are preferably double-sided cams, which act against a follower mounted to each wheel support. A potential benefit of using cam-driven cartridges is that cam-driven cartridges may allow for longer travel and smaller friction force variation than spring-loaded cartridges. 
     In an alternate embodiment, paddles or sails (not shown) may be used in combination with or in place of drive wheels  30 . When employing paddles or sails, air or liquid may be used to propel robot  10 . 
     Referring now to  FIG. 4 , a more detailed depiction of second segment  50  is shown. Second segment  50  preferably includes end sections  52 ,  54 , integrated circuit  58 , and battery  59 . Wiring/cables for sending information and/or power between components of robot  10  are preferably internal. For example, battery  59  provides electrical power to motor  56  ( FIG. 1 ). 
     End sections  52 ,  54  preferably house various additional components such as sensor and tool components. End section  54  preferably also serves as a platform for a plurality of non-pitched wheels  33  and their associated suspension systems. Unlike the wheel arrangement on first segment  20 , wheels  33  on second segment  50  are preferably aligned parallel to the longitudinal axis. Also, wheels  33  on at least one segment other than drive segment  20  preferably include an at least one optical encoder  31 . Optical encoder  31  allows navigation software to track the wheel revolutions and the direction of travel to compute the distance robot  10  has traveled. 
     In a preferred embodiment, at least one of pitched wheels  30  is capable of being dynamically engaged and disengaged. Disengagement can occur either in response to a signal from outside the tool or in response to a sensing event. When wheels  30  on drive segment  20  are disengaged, end section  22  will rotate freely, without advancing the device within the conduit. In this configuration, robot  10  becomes to a passive device that is propelled through the conduit by the flow of gas or liquid in the conduit. Alternatively, non-pitched wheels  33  could be disengaged, but it would be necessary to disengage at least one wheel on each wheeled section so as to allow each section to move freely within the conduit. 
     Integrated circuit  58  preferably includes a master control unit  64 , memory  66 , a communications interface  68  and input/output (I/O) controls  70 . In a preferred embodiment, master control unit  64  is a microprocessor (not shown). Memory  66  may include long-term memory and volatile memory components. In addition, software and databases may be located in memory  66 . Communications interface  68  is preferably adapted to receive and/or transmit information to a remote location via light, remote control, air pulses, acoustic or radio frequency waves, etc. In a preferred embodiment, communications interface  68  is an antenna (not shown). 
     I/O controls  70  preferably include sensors (not shown) such as Hall effect sensors, ultrasonic sensors, acoustic sensors, visual and optical inspection sensors, radiographic sensors, magnetic particle sensors, magnetic field sensors, electrical and eddy current sensors, penetrant sensors, pressure sensors, chemical sensors, leak sensors, microwave sensors, pressure and flow sensors, and thermal sensors, etc. I/O controls  70  may also include tools (not shown) such as repair and servicing tools, hardness testing tools, sample collection tools, etc. Further, I/O controls  70  preferably include actuators for motor control and navigation. 
     In integrated circuit  58 , master control unit  64  communicates with memory  66  to access information from I/O controls  70  and then stores the information in memory  66 . In some embodiments, master control unit  64  communicates with communications interface  68  to access information from I/O controls  70  and then stores the information in memory  66 . Master control unit  64  can also send information to I/O controls  70 . 
     Referring now to  FIG. 5 , a block diagram  100  of the software architecture in an embodiment of the present invention is shown. Block diagram  100  includes real-time operating system  110 , a database manager module  120 , a master control program module  130 , a fault detection and resolution module  140 , a navigation module  150 , a sensor management module  160 , a drive motor control module  170 , and a tool control module  180 . Real-time operating system  110  creates the environment for the rest of the modules to operate. 
     Database manager module  120  maintains and organizes the information or data in a database. Database manager module  120  communicates with navigation module  150 , sensor management module  160 , master control program module  130 , and fault detection and resolution module  140 . In a preferred embodiment, database manager module  120  receives and stores time-tagged information from navigation module  150  and sensor management module  160 . Database manager module  120  is also capable of recording significant events. 
     Master control program module  130  is the intelligence of robot  10 . Master control program module  130  communicates with database manager module  120 , sensor management module  160 , drive motor control module  170 , tool control module  180 , and fault detection and resolution module  140 . In a preferred embodiment, master control program module  130  schedules sensor and tool commands, which are implemented in sensor management module  160  and tool control module  180 , respectively. Master control program  130  also obtains location and sensor information from a database. 
     Fault detection and resolution module  140  preferably detects if a fault has occurred, whether the fault is software or hardware related, and how to correct the fault. Fault detection and resolution module  140  communicates with master control program module  130  and database manager module  120 . In a preferred embodiment, fault detection and resolution module  140  tests for locomotion failures and disengages wheels  30  and/or wheels  33  as necessary. As discussed above, when wheels  30  on drive segment  20  are disengaged, robot  10  reverts to a passive device propelled through the conduit by flowing gas or liquid. Fault detection and resolution module  140  may also test for and correct sensor, navigation, and tool failures. 
     Navigation module  150  records the along-track position of the wheel-mounted optical encoder  31 , time tags the information, and stores in it a database. Navigation module  150  communicates with database manager module  120 . 
     Sensor management module  160  collects information from and controls various sensors. Sensor management module  160  communicates with database manager module  120  and master control program module  130 . In a preferred embodiment, sensor management module  160  performs real-time information processing and stores reduced, time-tagged information in a database. 
     Drive motor control module  170  controls electric motor  62 . Drive motor control module  170  communicates with master control program module  130 . Drive motor control module  170  preferably receives and responds to commands from master control program module  130 . In a preferred embodiment, drive motor control module  170  sends information to electric motor  62  in the form of pulse-width modulated signals. 
     Tool control module  180  controls various tools. Tool control module  180  communicates with master control program module  130 . Tool control module  180  preferably receives and responds to commands from master control program module  130 . In a preferred embodiment, tool control module  180  generates tool-specific command signals. 
     Pipe-crawling robot  10  preferably also includes a power system. Referring now to  FIG. 6 , an alternative embodiment of the robot includes a third segment  80 . Segment  80  preferably includes a power supply, and is preferably an electric power module. In a preferred embodiment, power provided by segment  80  continuously or intermittently charges battery  59  on segment  50 . Second segment  50  is preferably connected to third segment  80  by a second flexible coupling  75 . 
     Similar to flexible coupling  75 , flexible coupling  105  is free to bend about the longitudinal axis of robot  10 , but prevents the relative rotation about the longitudinal axis. Flexible couplings  75 ,  105  are preferably capable of detaching from segments  20 ,  50 , and  80 . Also, additional flexible couplings (not shown) may be attached to segments  20 ,  50 , and  80 . The use of flexible couplings allows robot  10  to reduce or increase its number of segments, which may prove useful for unloading payloads, recovering payloads, etc., in a conduit. 
     Referring now to  FIG. 7 , a more detailed depiction of third segment  80  is shown. In a preferred embodiment, third segment  80  includes a turbine-based power supply system  82 . Turbine system  82  preferably includes a turbine or fan  84  (shown in phantom), a motor/generator  86 , and a shaft  88  (shown in phantom) disposed between fan  84  and motor/generator  86 . For purposes of the present invention, any mechanical device capable of extracting mechanical energy from a fluid flow, include one or more turbines, fans, paddles, and the like, can be used in turbine system  82 . For ease of reference, the term “fan  84 ” will be used to refer to all such devices. Turbine system  82  is preferably driven by air blown through the conduit (not shown), but may alternatively be powered by any fluid flow. Mechanical power extracted from the fluid flow as it spins the turbine is converted into electrical power by generator  86 . This power can be transmitted directly to motor  56  ( FIG. 1 ) so as to propel the robot, or it can be stored in battery  59 , or any combination of these. For example, the control system may sense when battery power is low and direct power to the battery in order to recharge it. An advantage of turbine system  82  is that it permits a virtually unlimited supply of electrical power without a practical limit on the distance robot  10  may travel in a conduit. 
     In an alternate embodiment, third segment  80  includes a battery system (not shown). In yet another alternate embodiment, third segment  80  includes a power tether (not shown). Battery systems and power tethers are desirable for use in applications of limited distance and involving relatively straight conduits. 
     Operation of Power System 
     Compressed air or inert gas is caused to flow through the conduit. This may be accomplished by the use of an air compressor or bottled compressed gas. The flowing gas turns the blades of fan  84 , which spin turbine shaft  88 . Turbine shaft  88  connects to electric generator  86 , which produces electricity (electric current). As discussed above, the electrical current is preferably used to recharge an onboard battery  59 , which provides power to drive the wheels  30 . Electric generator  86  also preferably provides power to integrated circuit  58 , sensors (not shown), and electric motor  62 . 
     Operation of Drive and Driver Segments 
     When instructed to turn on, shaft  26  of electric motor  56  causes end section  22  of first segment  20  to rotate about the longitudinal axis. This is accomplished because the longitudinally aligned wheels in end section  24  and second segment  50  resist the tendency of end section  24  and second segment  50  to rotate, thus the motor  56  torque causes end section  22  of first segment  20  to rotate. 
     For example, if shaft  26  and end section  22  are rotating in the clockwise direction (as viewed from the device), robot  10  is pulled in the forward direction. This is because the inclined wheels  30  on first segment  20  have the effect of screw threads, and thus the rotational motion of first segment  20  is transformed into longitudinal motion of robot  10 . 
     In order to reverse the direction of travel, shaft  26  of motor  56  is instructed to rotate in the opposite direction, i.e. counterclockwise. This causes end section  22  to rotate counterclockwise, and subsequently push robot  10  in the reverse direction. 
     In some embodiments, the speed at which shaft  26  rotates can be adjusted by motor  56 , causing robot  10  to accelerate or decelerate. When it is desirable for robot  10  to stop, motor  56  ceases movement of shaft  26 . 
     As stated above, in a preferred embodiment, the suspension system that supports each wheel is preferably a spring-loaded cartridge. Each spring-loaded cartridge includes a spring-loaded piston to which the wheels  30  are mounted. The spring-loaded piston  37  urges the wheel  30  outwardly so that the wheel can engage the conduit wall (not shown), which in turn induces sufficient friction to prevent slipping. When the suspension systems are cam-driven cartridges, the rotation of the cam induces a normal force between the wheel  30  and the conduit wall (not shown), again inducing sufficient friction to prevent slipping. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
     For example, while the present invention has been described having two or three separate modules or segments, it has been appreciated that any number or modules may be used. Likewise, the order and positioning of the segments in the device may be varied. Connected components may be connected either directly or indirectly. The use of additional modules may serve to house additional sensor or power equipment or carry various payloads. In some embodiments, the additional modules may be specialized for specific sensors. Furthermore, where the amount of data to be stored is excessive, it may be desirable to include multiple memory modules. Similarly, the position, numbering and configuration of pitched and non-pitched wheels can be varied without altering the basic operation of the device.