Perching UAV with releasable crawler

Abstract

To provide an unmanned aerial vehicle for an effective perching UAV having a releasable crawler for inspecting or maintaining a structure.SOLUTION: A UAV 100 includes a body, and three or more legs connected to the body and configured to land and perch the UAV on a curved ferromagnetic surface 50. Each leg includes a first portion connected to the body, a second portion including a magnet 120 and configured to magnetically attach and maintain the magnetic attachment of the leg to the ferromagnetic surface during the landing and perching, and a passive articulation joint connecting the first and second portions and configured to passively articulate the second portion with respect to the first portion in response to the second portion approaching the ferromagnetic surface. The UAV further includes a releasable crawler 150 including magnetic wheels, which detach the crawler from the body during the perching and maneuver the crawler on the ferromagnetic surface while magnetically attaching the crawler to the ferromagnetic surface after the detachment.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 62 / 772,700, filed November 29, 2018, and entitled "PERCHING UAV WITH RELEASABLE CRAWLER," and claims the benefit under 35 U.S.C. §120 of U.S. Application No. 16 / 689,864, filed November 20, 2019, and entitled "PERCHING UAV WITH RELEASABLE CRAWLER," each of which is incorporated by reference in its entirety herein.

[0002] The present disclosure relates generally to inspection and maintenance of structures, and more particularly to a perching unmanned aerial vehicle (UAV) having releasable and redockable crawlers for inspecting and maintaining structures. [Background technology]

[0003] Inspection and maintenance of exposed metal assets such as pipes, storage tanks, etc. can be difficult or impractical for humans to perform in some environments. In such situations, the use of automated UAVs (drones) can be an aid, providing a viable alternative. However, such inspection and maintenance tasks are often best performed using direct contact with the asset or by piloting the UAV over the asset, rather than hovering at a distance from the asset. In particular, performing a full circumferential scan of a pipe (or other asset) using a drone is a challenging task. Summary of the Invention [Problem to be solved by the invention]

[0004] With regard to these and other problems in the art, the present disclosure aims to provide a technical solution for an effective perching UAV with releasable crawlers for inspecting or maintaining structures. [Means for solving the problem]

[0005] According to one embodiment, an unmanned aerial vehicle (UAV) is provided. The UAV includes a body constructed to enable the UAV to fly, and three or more legs connected to the body and configured to land and perch the flying UAV on a curved ferromagnetic surface. Each leg includes a first portion connected to the body, a second portion including a magnet and configured to magnetically attach the leg to the ferromagnetic surface during landing and to maintain magnetic attachment of the leg to the ferromagnetic surface during perching, and a passive articulation joint connecting the first portion to the second portion and configured to passively articulate the second portion relative to the first portion during landing in response to the second portion approaching the ferromagnetic surface. The UAV further includes a releasable crawler including a magnetic wheel configured to separate the crawler from the body during perching and to steer the crawler over the ferromagnetic surface while the crawler magnetically attaches to the ferromagnetic surface after separation.

[0006] In one embodiment, the crawler further comprises a probe or tool configured to inspect or maintain the ferromagnetic surface during maneuvering.

[0007] In one embodiment, the crawler further comprises wireless communication circuitry configured to wirelessly communicate with the UAV or a base station.

[0008] In one embodiment, the magnetic wheels are further configured to redock the crawler to the body after maneuvering.

[0009] In one embodiment, each magnet comprises a permanent magnet.

[0010] In one embodiment, each magnet comprises a switchable permanent magnet.

[0011] In one embodiment, each magnet comprises an electropermanent magnet.

[0012] In one embodiment, the UAV further comprises a separation actuator configured to apply leverage to a second portion of one or more of the legs that are magnetically attached to the ferromagnetic surface to assist in magnetically separating one or more of the magnetically attached legs from the ferromagnetic surface during takeoff from the perched UAV's ferromagnetic surface.

[0013] In one embodiment, the UAV further comprises a laser scanner coupled to the body and configured to provide sensory data for orienting the UAV upon landing.

[0014] In one embodiment, the magnet wheels comprise four magnet wheels, and the crawler further comprises two motors each configured to drive two of the four magnet wheels.

[0015] In one embodiment, the magnetic wheel comprises an omni wheel or a mecanum wheel.

[0016] According to another embodiment, an unmanned aerial vehicle (UAV) is provided. The UAV includes a first body having a plurality of first attachment points and a substructure constructed to enable the UAV to fly. The substructure includes a second body having a corresponding plurality of second attachment points attached to the first body at corresponding pairs of the first and second attachment points, and three or more legs connected to the second body and configured to land and perch the flying UAV on a curved magnetic surface. Each leg includes a first portion connected to the second body, a second portion including a magnet and configured to magnetically attach the leg to the ferromagnetic surface during landing and to maintain the leg magnetically attached to the ferromagnetic surface during perching, and a passive articulation joint connecting the first portion to the second portion and configured to passively articulate the second portion relative to the first portion during landing in response to the second portion approaching the ferromagnetic surface. The undercarriage further comprises a releasable crawler comprising a magnetic wheel configured to separate the crawler from the second body during perching and to steer the crawler over the ferromagnetic surface while magnetizing the crawler to the ferromagnetic surface after separation.

[0017] In one embodiment, the crawler further comprises a probe or tool configured to inspect or maintain the ferromagnetic surface during maneuvering.

[0018] In one embodiment, the crawler further comprises wireless communication circuitry configured to wirelessly communicate with the UAV or a base station.

[0019] In one embodiment, the magnetic wheel is further configured to redock the crawler to the second body after maneuvering.

[0020] In one embodiment, each magnet comprises a permanent magnet.

[0021] In one embodiment, each magnet comprises a switchable permanent magnet.

[0022] In one embodiment, each magnet comprises an electropermanent magnet.

[0023] In one embodiment, the UAV further comprises a separation actuator configured to apply leverage to a second portion of one or more of the legs that are magnetically attached to the ferromagnetic surface to assist in magnetically separating one or more of the magnetically attached legs from the ferromagnetic surface during takeoff from the perched UAV's ferromagnetic surface.

[0024] In one embodiment, the UAV further comprises a laser scanner coupled to the first body and configured to provide sensory data for orienting the UAV during landing.

[0025] In one embodiment, the magnet wheels comprise four magnet wheels, and the crawler further comprises two motors each configured to drive two of the four magnet wheels.

[0026] In one embodiment, the magnetic wheel comprises an omni wheel or a mecanum wheel.

[0027] In one embodiment, the undercarriage further comprises a docking mechanism configured to secure the crawler to the second body during flight, and a height adjustment mechanism configured to adjust the height of the crawler relative to the ferromagnetic surface during the perch.

[0028] In one embodiment, the first body further has a corresponding plurality of third attachment points, and the second body is configured to be separated from the first body at the first attachment points and attached to the first body at corresponding pairs of the third and second attachment points.

[0029] In one embodiment, the first body includes a movable mount having a first attachment point and configured to move the first attachment point relative to a remainder of the first body.

[0030] In one embodiment, the UAV further comprises a motor configured to move the mount during flight.

[0031] In one embodiment, the movable mount is further configured to rotate the first attachment point about an axis of the first body.

[0032] Any combination of the various embodiments and implementations disclosed herein may be used. These and other aspects and features can be understood from the following description of specific embodiments, taken in conjunction with the accompanying drawings and claims. [Brief description of the drawings]

[0033] [Figure 1A] 1A-1C are diagrams of an example of a UAV perching on a structure (e.g., a pipe), where the UAV has releasable crawlers for inspecting or maintaining the structure, according to one embodiment. [Figure 1B] 1A-1C are diagrams of an example of a UAV perching on a structure (e.g., a pipe), where the UAV has releasable crawlers for inspecting or maintaining the structure, according to one embodiment. FIG. 1B shows the crawlers not attached to the UAV (e.g., crawling on the structure). [Figure 2A] FIG. 1 illustrates an exploded and cross-sectional view of an exemplary UAV or drone, according to one embodiment, comprising an undercarriage having perching legs for perching on a structure. [Figure 2B] FIG. 1 illustrates an exploded and cross-sectional view of an exemplary UAV or drone, according to one embodiment, configured with an undercarriage having crawlers for releasing the UAV from a perched on a structure for inspecting or maintaining the structure. [Figure 3A] FIG. 2C is a cross-sectional view of an exemplary UAV having modular mounting points for attaching the undercarriage of FIGS. 2A and 2B, according to one embodiment. [Figure 3B]1 is a cross-sectional view of a UAV having a lower structure mounted in a lateral and upper orientation relative to the UAV, according to one embodiment. [Figure 3C] 1 is a cross-sectional view of a UAV having a lower structure mounted in a lateral and upper orientation relative to the UAV, according to one embodiment. [Figure 4A] 2A-3C, with the undercarriage mounted in a bottom orientation, a top orientation, and a side orientation, respectively, relative to the UAV, in accordance with one embodiment, a cross-sectional view of an exemplary UAV having rotatable mounting points for mounting the undercarriage of FIGS. [Figure 4B] 2A-3C, with the undercarriage mounted in a bottom orientation, a top orientation, and a side orientation, respectively, relative to the UAV, in accordance with one embodiment, a cross-sectional view of an exemplary UAV having rotatable mounting points for mounting the undercarriage of FIGS. [Figure 4C] 2A-3C, with the undercarriage mounted in a bottom orientation, a top orientation, and a side orientation, respectively, relative to the UAV, in accordance with one embodiment, a cross-sectional view of an exemplary UAV having rotatable mounting points for mounting the undercarriage of FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Please note that the drawings are illustrative and are not necessarily to scale, and that the same or similar features have the same or similar reference numbers throughout.

[0035] In various exemplary embodiments, a perching UAV is provided having releasable crawlers for inspecting or maintaining elevated or otherwise inaccessible structures such as pipes or storage tanks.

[0036] The UAV is a hybrid UAV with advanced capabilities to perform contact inspection operations on curved ferromagnetic surfaces, such as carbon steel pipes, storage tanks, and other structures. The UAV can fly toward the pipe to be inspected, land autonomously (commonly referred to as perching), and deploy releasable magnetic crawlers to crawl around the pipe, for example, to perform intricate inspection operations at any orientation angle. The crawlers can also be configured to perform maintenance on the pipe. As will be appreciated from the discussion below, the UAV can land, for example, on top of, to the side of, or directly underneath the pipe or other structure, and in each instance is said to have landed on the structure.

[0037] As mentioned previously, it can be difficult or impractical for people to inspect and maintain exposed metal assets such as pipes, storage tanks, etc. For example, one of the biggest challenges in the oil and gas industry is the regular inspection of elevated assets found in refineries, gas plants, offshore platforms, and other plants and facilities. These assets include elevated pipes and structures that are difficult to access during inspection or maintenance work. Sometimes the only way for people to inspect or maintain them is to erect scaffolding so that an inspector or engineer can access the asset and perform manual inspections, for example, using ultrasonic inspection (UT) sensors for thickness measurements. Such scaffolding is expensive, posing a significant cost barrier to frequent inspections, as well as raising safety concerns, primarily in the form of fall and tripping hazards.

[0038] Thus, in an exemplary embodiment, a perching UAV with releasable crawlers provides a solution to the aforementioned technical problem by having two vehicles in a mother-son configuration. Each vehicle is designed or optimized to perform the most suitable performance. The vehicles include a perching UAV that can fly over and land on the pipe, and a small magnetic crawler that is carried by the UAV and released from the UAV after landing or perching. The crawler can move around on the pipe to perform inspection scans, such as thickness measurements using a UT sensor. For example, in some embodiments, both the UAV and the crawler magnetically attach to the curved surface of the pipe or other asset being inspected or maintained. As such, the crawler can perform a complete longitudinal or circumferential scan of the asset (even upside down relative to gravity).

[0039] This provides a more feasible approach than having the entire UAV crawl around the pipe, which requires larger and heavier motors and risks collision with nearby pipes and assets, especially when clearance constraints are limited. A perched UAV also saves energy (e.g., electrical energy, battery energy, etc.) by perching on (e.g., on top of) the pipe as opposed to hovering close to the pipe. Perching the UAV on the face of the pipe also allows the releasable crawler to be released from or redocked on the UAV more easily than when the UAV is hovering next to the pipe. Additionally, perching provides more stability and reduced risk compared to hovering.

[0040] 1A and 1B are diagrams of an exemplary UAV 100 perched on a structure 50 (e.g., a pipe) according to one embodiment, the UAV 100 having a releasable crawler 130 for inspecting or maintaining the structure 50. The crawler 130 is shown attached to the UAV 100 in FIG. 1A and not attached to the UAV 100 (e.g., crawling on the structure 50) in FIG. 1B. For ease of explanation, the structure 50 is assumed throughout to be larger (e.g., significantly larger) than the UAV 100. For example, the structure 50 is larger in all dimensions than the UAV 100. Or, the proposed landing area provided by the structure 50 is larger than the proposed landing area of ​​the UAV 100. Additionally, for ease of explanation, the structure 50 (or any structure described herein) is assumed to be a pipe, such as a pipe with a diameter of 8 inches or more.

[0041] 1A and 1B show the mother-son configuration in operation. FIG. 1A shows the UAV 100 after landing on the pipe 50 with the crawler 130 still docked. FIG. 1B shows the crawler 130 after being released from the UAV 100 to perform inspection operations. The crawling capability provided by the releasable crawler 130 gives the UAV 100 important features for inspection and maintenance operations such as easier accessibility (e.g., no need to land at the exact spot where the inspection or maintenance is to be performed). Crawling further provides circumferential and longitudinal scanning. For example, in the oil and gas industry, it is important to perform a full scan of the pipe 50 to find the minimum steel thickness in a particular area of ​​the pipe 50. Such scans often include circumferential and longitudinal scans, for which crawling is well suited. Crawling further provides power efficiency during multiple inspections (e.g., crawling between multiple inspection sites on the same pipe is more power efficient than flying).

[0042] 1A and 2B, the UAV 100 utilizes four articulated magnets 120 (such as permanent magnets or switchable permanent magnets). To accommodate landing of the UAV 100 on the pipe 50, each magnet 120 (or, more precisely, its magnetic field) is articulated in a perpendicular orientation relative to the pipe 50 when the UAV 100 lands on or is perched on the pipe 50.

[0043] In some embodiments, the magnetic field of the joint magnet 120 can be actively switched on and off (e.g., to allow for easy removal after work is completed). A laser scanner 110 (e.g., light detection and ranging, or LIDAR) is included as a form of real-time feedback to measure, for example, the relative position of the pipe to the UAV 100 during the automatic landing maneuver. In some embodiments, the miniature crawler 130 is connected by wires (e.g., for power and communication) and includes the UT sensor, four magnetic wheels 140, and two motors for driving the wheels 140 in corresponding pairs (e.g., front and rear). The wires also allow the remaining electronics and batteries to be located within the UAV body 100 for performing inspection or maintenance. This reduces the size, weight, and complexity of the crawler 130.

[0044] In some other embodiments, the crawler 130 includes a different number of wheels 140 (e.g., two or three wheels, or four or more) and their types (omni wheels, mecanum wheels, etc., to name a few). Unlike an unmanned ground vehicle (UGV), the magnetic crawler 130 must contend with the various curvatures and various orientations (as shown throughout) of a pipe inspection or maintenance. Thus, in some embodiments, the magnetic crawler 130 has a specialized locomotion system for navigating the curvature of a pipe (or similar curvatures from other curved structures or vessels).

[0045] In some embodiments, communication between the crawler 130 and the UAV 100 is wired. For example, using a small spool of thin cord, the crawler 130 can be connected to the UAV 100 for power and communications. This can, for example, eliminate the need to carry batteries and other electronics within the crawler 130, allowing the crawler to be smaller and save overall weight by utilizing some components already present in the UAV 100.

[0046] In some other embodiments, the communication between the crawler 130 and the UAV 100 is wireless. Here, the crawler 130 includes its own battery and electronics to provide a more independent vehicle. This may be useful, for example, when the UAV 100 picks up the crawler 130 from the ground and deploys it to the pipe 50. At that point, the UAV 100 can fly off and do some other inspection work and then return to pick up the crawler 130. This is also useful when multiple crawlers 130 (e.g., a fleet of crawlers 130) are inspecting multiple assets. The UAV 100 picks them up from the ground, one by one or in batches, to their destination and then retrieves them when the work is completed. In different embodiments, the wireless connection can be between the crawler 130 and either the UAV 100 or the operator's control station, or both the UAV 100 and the operator's control station.

[0047] In one embodiment, the UAV 100 includes a body (e.g., having rotors, control devices, and guidance devices, etc.) constructed to enable flight of the UAV 100. The UAV 100 also includes three or more legs connected to the body and configured to land and perch the flying UAV 100 on a curved ferromagnetic surface 50. Each leg includes an upper (or main) portion connected to the body and a lower portion including a permanent magnet 120. The bottom portion is configured to magnetize the leg to the ferromagnetic surface 50 upon landing and to remain magnetized to the ferromagnetic surface while perching. Additionally, a passive articulation joint connection connects the upper and lower portions of the legs and passively articulates (e.g., pivots) the lower portion relative to the upper portion in response to the lower portion approaching the ferromagnetic surface 50 during landing. The UAV 100 further includes a releasable crawler 130 having magnetic wheels 140. The magnetic wheels 140 allow the crawler 130 to be separated from the UAV 100 during perching, and after separation, allow the crawler 130 to move over the ferromagnetic surface 50 while remaining magnetically attached to the ferromagnetic surface 50.

[0048] In different embodiments, different landing mechanisms for the UAV 100 can be used. These can include various types of attachment mechanisms, such as magnetic or non-magnetic. Examples of magnetic landing mechanisms include magnets that can be blocked or overcome by mechanical means during takeoff from the pipe 50. Such magnets include switchable permanent magnets, permanent magnets with actuating levers to aid in detachment during takeoff, electro-permanent magnets, and electromagnets. However, it is noted that continuous power consumption can be a disadvantage for electromagnets. Non-magnetic attachment mechanisms can be used on non-ferromagnetic surfaces such as stainless steel, composite pipes, concrete walls, etc. Such mechanisms include microspine, suction cups, grippers, and crawlers, which are gecko-inspired dry adhesives (such as synthetic bristles).

[0049] Different embodiments use different crawler loads or designs. For simplicity, these loads or designs are categorized into two basic categories: inspection and maintenance. The inspection loads and designs include various types of sensors commonly used in the oil and gas industry to inspect pipes and structures. For example, in some embodiments, UT sensors are used for thickness measurement. For ease of explanation, UT sensors for thickness measurement are sometimes used throughout to represent exemplary devices and applications for inspection and maintenance. However, other embodiments are not limited to such devices or applications. For example, other inspection sensors or probes can be used in place of or in addition to UT sensors depending on the task, including (but not limited to) eddy current sensors and alternating current field measurement (ACFM) sensors.

[0050] In yet other embodiments, the crawler 130 is configured with one or more tools and used for maintenance purposes. For example, the crawler 130 can be used to perform light maintenance tasks such as cleaning, surface preparation, and coating repair. In yet other embodiments, the crawler 130 is configured with one or more cameras and used for visual inspection. For example, in some embodiments, the cameras are used for simple visual inspection tasks, such as areas where only video or photos of the area of ​​interest need to be obtained, but where the area is difficult to inspect directly by the UAV 100.

[0051] In some embodiments, the crawler 130 is configured to leave markers (such as paint or QR codes) in areas of interest (where sensor readings are outside normal levels, where faults are detected, etc.). For example, these locations may be where critical thickness levels are detected. In some such embodiments, the UAV 100 scans these markers after the crawler 130 redocks and the UAV 100 flies away, and creates a 3D reconstruction of the environment showing the exact locations of these markers. In some such embodiments, the UAV 100 detects the markers using an on-board RGB-D camera and calculates their location relative to the UAV 100. The GPS location of the UAV can be used to calculate or otherwise determine the absolute location of the markers. It should be noted that while the UAV 100 is scanning the markers, the crawler 130 can remain on the pipe 50 or redock with the UAV 100, for example.

[0052] In some embodiments, the crawler 130 uses radio localization to identify where there are problems on the asset, such as with virtual markers. In other words, the location of the defects can be identified without physical markers, although with less accuracy. This is because the position of the crawler relative to the UAV 100 can be calculated (or otherwise determined) using radio sensors. For example, in some such embodiments, the UAV 100 carries an ultra-wide band (UWB) sensor array that receives radio signals from another UWB transmitter mounted on the crawler 130. The relative position of the crawler can then be measured regardless of whether the UAV 100 is in flight or attached to the pipe 50. In some embodiments, whenever the operator finds an obstacle during the crawl, the position of the crawler relative to the UAV 100 is tagged and captured. Using the UAV's GPS sensors, the absolute location of these defects can be identified. In some embodiments, when GPS is unavailable, the position of the UAV is estimated based on flight trajectory and IMU data from a home base where GPS is available.

[0053] In some embodiments, the pre-calculated (or determined) inspection positions are transferred from the UAV 100 to an operational computer or ground station. The inspection positions are then visualized in a 3D model, which can be built, for example, on a pre-created 3D model of the plant to be inspected or on the UAV's on-board sensors (e.g., depth camera or 3D LIDAR). Furthermore, in some such embodiments, the visualized positions are annotated with the corresponding measurement thickness (or other sensed values ​​or information).

[0054] 2A and 2B are exploded and cross-sectional views, respectively, of an exemplary UAV 200 or drone, according to one embodiment, comprising (1) a substructure 220 with perching legs 280 for perching on a structure 150 (carbon steel pipe or other curved ferromagnetic surface 150) and (2) a substructure with crawlers 260 for releasing the UAV 200 from perching on the structure 150 to inspect or maintain the structure 150. The crawlers 260 have magnetic wheels 270 for steering while adhering to the curved ferromagnetic surface 150 (e.g., regardless of orientation relative to gravity, even upside down). For ease of explanation, a pipe is used throughout as an example structure with a curved ferromagnetic surface. However, the described embodiments are equally applicable to other such structures, such as cylindrical or spherical storage tanks with curved ferromagnetic surfaces. The UAV 200 or drone may include rotors (such as four or six rotors) and a control unit for adjusting the rotational speed of each rotor to balance the load of the UAV 200 or move the UAV 200 in a desired direction.

[0055] 2A and 2B, the UAV 200 includes a set of attachment points 210 for mating with a set of similar attachment points 230 on the undercarriage 220. In this manner, any compatible UAV / undercarriage combination (e.g., compatible attachment points and payload capacity / weight) can be assembled for a desired purpose, in this case a releasable crawler 260 for deploying to and inspecting or maintaining the structure 150. To this end, the undercarriage 220 includes a set of perching legs 280 (e.g., four such legs 280), each having an articulated magnet 290. The articulated magnets 290 are attached to the legs 280 such that they can be oriented toward and adhere to the curved ferromagnetic surface 150 as the UAV 200 approaches and perches on the surface 150.

[0056] Thus, as shown in FIG. 2A , the articulating joint allows for the magnet 290 to pivot within the housing of the magnet 290 relative to the surface 150 where the leg 280 just perches, such as when the joint includes a universal joint. As shown, the pivoting can be about the axis of the leg 280 or the joint, and can assume angles relative to the axis, such as angle φ and optionally an additional angle θ. The UAV 200 and undercarriage 220 are primarily configured to perch and deploy or retrieve the crawler 260 on (or near) a structure (e.g., to keep the rotor of the UAV 200 at an appropriate level before, during, or after perching).

[0057] Additionally, the undercarriage 220 includes a height adjustment mechanism 240 (e.g., a motor or other actuator) for lowering the crawler 260 from the perched UAV 200 to the surface 150 or for raising the crawler 260 from the surface 150 to the perched UAV 200. To assist with this, the docking mechanism 250 connects the height adjustment mechanism 240 to the crawler 260, such as with a docking port. The docking port allows the crawler 260 to disengage (e.g., be flipped off) from the perched UAV 200 after it has been deployed to the surface 150, or to engage (e.g., run into or onto) the perched UAV 200 when it is ready to leave the surface 150, such as for returning to a home base or other structure or component to be inspected or maintained. The docking mechanism 250 may also allow for the transfer of information or energy between the UAV 200 and the crawler 260. For example, instrumentation data may be downloaded from the crawler 260 to the UAV 200 or the crawler 260's batteries may be recharged from the UAV 200.

[0058] More specifically, in some embodiments, the height adjustment mechanism 240 is used to adjust the height of the crawler 260 based on the pipe diameter (e.g., for successful release at the surface 150). For example, on a large pipe (or plane), the docked crawler 260 will be at a higher height to the surface 150 than on a small diameter pipe. Thus, for a large pipe (or plane), the crawler 260 is deployed at a lower height to reach the surface 150, whereas for a small diameter pipe, the crawler 260 is deployed and released at a higher point. Additionally, in some embodiments, the height adjustment mechanism 240 is used to redock the crawler 260 after the job is completed. This allows the docking mechanism 250 to be at the correct height relative to the crawler 260. Again, different pipe diameters correspond to different heights. In some embodiments, the height adjustment mechanism 240 is used to pull the crawler 260 and break its magnetic attachment to the ferromagnetic surface 150.

[0059] In some embodiments, height adjustment mechanism 240 is actuated by a motor or the like. In some embodiments, height adjustment mechanism 240 is passive when not used to separate crawlers 260. For example, in one such embodiment, height adjustment mechanism 240 is spring loaded so that it can always push pipe 150 at its maximum possible extension when UAV 200 perches to deploy crawlers 260.

[0060] For the UAV 200 with the undercarriage 220, it is desirable to approach and land near the top surface of the pipe 150 (e.g., at or near the 12 o'clock position) at a straight or near straight angle, typically providing attachment of the legs 280 and appropriate perching. The perching legs 280 have features useful for successful perching and attachment to the pipe 150. For example, each leg 280 of the perching mechanism features an articulated magnet 290 (such as a permanent magnet or a switchable permanent magnet). The articulation of the legs 280 is passive when the UAV 200 (more precisely, the attached undercarriage 220) is in close proximity to the ferromagnetic surface 150 of interest, such as in response to the initial contact of the magnet 290 with the ferromagnetic surface 150, in that the articulated magnet 290 is designed to articulate about the axis shown in FIG. 2A in response to the magnetic attraction of the magnet 290 and the ferromagnetic surface 150. It should be noted that undercarriage 220 can be attached to any UAV having suitable attachment points (e.g., for mating with attachment points 230) and payload capacity (e.g., for carrying and deploying undercarriage 200 during flight).

[0061] In some embodiments, after deployment and completion of the operation, the crawler 260 redocks with the UAV 200, or more specifically, with the docking mechanism 250. The process of redocking and takeoff from the ferromagnetic surface 150 by the UAV 200 using the crawler 260 also includes magnetically isolating the crawler 260 from the surface 150. In some such embodiments, the UAV 200 uses the height adjustment mechanism 240 to lever the crawler 260 away from the magnetic attraction of the magnetic wheels 270 of the crawler 260 and the ferromagnetic surface 150. In some other such embodiments, the magnetic wheels 270 use switchable magnets to disable adhesion to the ferromagnetic surface 150 after redock. In still other such embodiments, the docking mechanism 250 includes a ramp on the pipe 150 and attached to the UAV 200. In such embodiments, the crawler 260 climbs the ramp while redocked (such as parking on a sloped roadway). In this manner, the crawler's wheel motors are used to forcefully separate the magnets of the magnetic wheels 270 using the drive torque of the crawler 260. The ramp can be made of metallic materials (e.g., steel) or non-magnetic materials depending on factors such as weight, strength, etc. In each such embodiment, magnetic attraction of the UAV 200 is achieved to enable the UAV 200 to fly to its next location, with the crawler 260 as a payload safely held by the UAV 200.

[0062] 3A is a cross-sectional view of an exemplary UAV 300 having modular mounting points 310 for mounting the undercarriage 220 of FIGS. 2A and 2B, according to one embodiment, while FIGS. 3B and 3C are cross-sectional views of a UAV 300 having the undercarriage 220 mounted in a lateral and upper orientation, respectively, relative to the UAV 300, according to one embodiment. This modular approach allows for the undercarriage 220 (payload) to be mounted, for example, at the bottom, front, or top of the UAV 300 to be able to perch on the top, side, or bottom of the pipe 150, respectively.

[0063] One of the biggest challenges in inspecting pipes in refineries is that many of the pipes are not accessible from above due to obstacles such as racks, structures, other pipes, etc. In these cases, it is desirable to access or perch such surfaces from other positions, such as the side or bottom of the structure. The UAV 300, along with the undercarriage 220 attached to a suitable set of mounting points 310, can perch on the top, side, or bottom of the pipe 150 using the adaptable perching legs 280, as shown in Figures 3A, 3B, and 3C, respectively.

[0064] More specifically, each leg 280 is designed with an articulating magnet 290 that splits the leg 200 into two separate parts, a main body that is firmly attached to the undercarriage 220, and a movable (or articulating) magnet 290. This provides the legs 280 with at least a rotational degree of freedom, which allows the magnets 290 to passively realign their orientation (e.g., vertical) towards the pipe 150 during landing, allowing for full or near-perfect adhesion.

[0065] Note that for ease of illustration of the 2D side view, features such as rotors of UAV 300 may be shown touching other portions of UAV 300 (such as perching legs 280). However, this is because the depth dimension (where such features do not overlap) is not shown. The rotors of UAV 300 do not interfere with undercarriage 220 in any configured orientation of undercarriage 220 (e.g., undercarriage 220 is between the rotors when viewed from above).

[0066] It should also be noted that changing the location of the undercarriage 220 changes the center of gravity of the UAV 300. Therefore, the UAV 300 needs to compensate for this change. In some embodiments, the on-board flight controller of the UAV 300 is configured (e.g., by logic, code, etc.) to keep the UAV 300 in a stable hover regardless of weight distribution. For example, if the UAV 300 becomes front-heavy, the controller is configured to sense a slight tilt and increase the thrust or rotational speed on the heavy side to compensate for the tilt in order to keep the UAV 300 level and stable. In some embodiments (as shown in Figures 4A to 4C), to reduce the effect of the change in center of gravity, heavy components such as batteries are placed on the rotating rail opposite the undercarriage 220. This makes it easier for the flight controller to keep the UAV 200 stable even in situations where the undercarriage 220 is not directly underneath the UAV 200.

[0067] 4A, 4B, and 4C are cross-sectional views of an exemplary UAV 400 having a rotatable mounting point 410 for mounting the undercarriage 220 of FIGS. 2A-3C, with the undercarriage 220 mounted in bottom, top, and side orientations, respectively, relative to the UAV 400, according to one embodiment. In some embodiments, the UAV 400 includes a motor or actuator for rotating the mounting point 410 to a preferred orientation, including during flight (e.g., dynamic rotation). In some other embodiments, the mounting point 410 can be manually rotated to a desired orientation prior to a mission (e.g., static rotation).

[0068] In an exemplary motorized embodiment, a motorized system (e.g., motorized attachment points 410 and a motor for rotating attachment points 410 to orbit around the UAV 400) allows an operator to change the orientation of the undercarriage 220 (payload) at the push of a button. In another embodiment, the UAV 400 automatically changes the orientation of the undercarriage 220 (e.g., in flight) in response to factors such as observed or known obstacles around the pipe 150. With this in mind, FIGS. 4A, 4B, and 4C illustrate how a motorized system can change the orientation of the perching legs 280 to land on the top, bottom, or side of the pipe 150, respectively.

[0069] For example, in one embodiment, the UAV has a controller configured (e.g., by computer code) to plan the safest location on the pipe 150 to perch, such as the top, side, or bottom of the pipe 150, or somewhere in between. In the exemplary motorized embodiment shown in Figures 4A-4C, rotation is accomplished via a circular rail around the body 400 of the UAV. Thus, to maintain a proper center of gravity during rotation, heavy components such as batteries can be placed on the rail (e.g., opposite the mounting point 410) to act as a counterweight.

[0070] In an exemplary user adjustable (e.g., manual) embodiment, the rotation of the undercarriage 220 is manually adjusted by a user instead of being motorized. For example, this may be done to save weight, complexity, power, etc. An exemplary technique for achieving this manual adjustment is by loosening a hand screw to unlock the manual rotation of the undercarriage 220 about the circular rail, which can then be relocked once the undercarriage 220 is in the desired position.

[0071] The methods described herein may be performed in part or in whole by software or firmware in machine-readable form on a tangible (e.g., non-transitory) storage medium. For example, the software or firmware may be in the form of a computer program adapted to perform some or all steps of any method described herein, and the computer program may be embodied on a computer-readable medium when the program is executed on a computer or suitable hardware device (e.g., FPGA). Examples of tangible storage media include computer storage devices, including computer-readable media such as disks, thumb drives, memory, etc., and do not include propagated signals. Although propagated signals may reside on tangible storage media, the propagated signals themselves are not examples of tangible storage media. The software may be suitable for execution on parallel or serial processors, such that the method steps may be performed in any suitable order or simultaneously.

[0072] It should be further understood that like numerals in the drawings represent like elements throughout the several drawings, and that not all of the components and / or steps described and illustrated in connection with the drawings are required in all embodiments or configurations.

[0073] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0074] Orientation terms are used herein merely for convention and reference purposes and should not be construed as limiting. However, it is recognized that these terms may be used relative to the viewer. Thus, no limitation is implied or inferred. Furthermore, the use of ordinal numbers (e.g., first, second, third) is for distinction and not for counting. For example, "third" does not suggest that there is a corresponding "first" or "second". Additionally, the phraseology and terminology used herein are for descriptive purposes and should not be considered as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein is intended to encompass the items listed thereafter, and equivalents thereof, as well as additional items.

[0075] The subject matter described above is provided merely by way of example and should not be construed as limiting. Various modifications and changes may be made to the subject matter described herein without following the exemplary embodiments and applications described and without departing from the true spirit and scope of the present disclosure as set forth in the following claims. [Explanation of symbols]

[0076] 50 Curved ferromagnetic surfaces (structures, pipes) 100 UAV body 110 Laser Scanner 120 Joint Magnet 130 Magnetic Crawler (Miniature Crawler) 140 Magnetic Wheel 150 Curved ferromagnetic surface 200 Legs 210 attachment points 220 Undercarriage 230 attachment points 240 Adjustment mechanism 250 Docking Mechanism 260 Crawler 270 Magnetic Wheel 280 Legs 290 Magnet 310 modular attachment points 400 Body 410 Powered Attachment Point

Claims

1. An unmanned aerial vehicle (UAV), a body constructed to enable the UAV to fly; Three or more legs connected to the body and configured to land and perch the flying UAV on a curved ferromagnetic surface, each leg comprising: a first portion connected to the body; a second portion including a magnet and configured to magnetically attach the legs to the ferromagnetic surface during the landing and to maintain the legs on the ferromagnetic surface during the perch; and a passive articulation joint connecting the first portion to the second portion and configured to passively articulate the second portion relative to the first portion during landing in response to the second portion approaching the ferromagnetic surface; and a separation actuator configured to apply leverage to the second portions of the one or more of the legs magnetically attached to the ferromagnetic surface to assist in magnetically separating the one or more of the magnetically attached legs from the ferromagnetic surface during takeoff of the perched UAV from the ferromagnetic surface; A releasable crawler comprising a magnetic wheel, the magnetic wheel comprising: separating the crawler from the body during the perch; and after the separation, maneuvering the crawler over the ferromagnetic surface while magnetically attracting the crawler to the ferromagnetic surface.

2. The UAV of claim 1 , wherein the crawler further comprises a probe or tool configured to inspect or maintain the ferromagnetic surface during the maneuver.

3. The UAV of claim 1 , further comprising wireless communication circuitry configured for the crawler to wirelessly communicate with the UAV or a base station.

4. The UAV of claim 1 , wherein the magnetic wheels are further configured to redock the crawler to the body after the steering.

5. The UAV of claim 1 , wherein each magnet comprises a permanent magnet.

6. The UAV of claim 5 , wherein each magnet comprises a switchable permanent magnet.

7. The UAV of claim 6 , wherein each magnet comprises an electropermanent magnet.

8. The UAV of claim 1 , further comprising a laser scanner connected to the body and configured to provide sensory data for orienting the UAV during the landing.

9. 2. The UAV of claim 1, wherein the magnet wheels comprise four magnet wheels, and the crawler further comprises two motors each configured to drive two of the four magnet wheels.

10. The UAV of claim 1 , wherein the magnetic wheel comprises an omni wheel or a mecanum wheel.

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