Repairing structures using unmanned aerial vehicles

Abstract

To provide methods and apparatus for performing repair operations using an unmanned aerial vehicle (UAV 2).SOLUTION: The methods are realized by equipping an unmanned aerial vehicle (UAV) with tools for rapidly repairing a large structure or object (e.g., an aircraft or a wind turbine blade) that is not easily accessible to maintenance personnel. Multiple tools are available for robotic selection and placement at a repair site 9. The tools are designed to perform respective repair operations in sequence in accordance with a specified repair plan. The plan may take into account results of a previously performed UAV-enabled inspection.SELECTED DRAWING: Figure 2B

Description

[Technical field]

[0001] The present disclosure relates generally to the inspection and repair of structures. In particular, the present disclosure relates to the use of unmanned aerial vehicles (UAVs) for in-flight repair of inaccessible or limited access structures. [Background technology]

[0002] In-service manual repairs of large structures and large objects of various kinds are time consuming, expensive, and difficult for individuals to perform. Examples of large structures that are significantly more difficult to repair include infrastructure associated with wind turbine blades, aircraft fuselages and wings, rockets and satellites, storage tanks, bridges, dams, levees, power plants, power lines or grids, water treatment plants, oil refineries, chemical processing plants, high rise buildings, and support structures for trains and monorails.

[0003] More specifically, materials and structures employed in the aerospace industry and elsewhere may require periodic repairs for in-service damage. Rapid inspection and repair of aircraft is important for military and civilian applications to reduce downtime. For example, the use of composite structures is becoming increasingly common for civilian aircraft. Composites may be damaged during the course of service. Examples of such in-service damage include lightning strikes, impact damage from hail, runway debris, or collisions with ground support vehicles.

[0004] In instances where an inspection of a structure determines that the structure should undergo repairs, such as to address structural anomalies identified during the inspection, the repairs should be performed in a timely manner such that the structure can be quickly returned to service. For example, damage may be discovered at an airport loading gate just prior to departure. Depending on the extent of the damage, repairs may be provided that may be temporary or permanent. This may be non-structural (such as sealing a surface to keep moisture out) or structural (restoring an area to some level of strength). The current approach to repairing impacts, delaminations, scratches, cracks, burns, or tears on most operational aircraft (composite or metal) is to use human labor with lifts or stands, safety harnesses, etc. For minor or temporary repairs, this results in unnecessary operational delays, exposure to potential safety conditions, and the cost of returning the aircraft to flight. The cost of access, labor, and associated time to perform the repairs, as well as lost revenue during the downtime, can be costly. If repair equipment is not available or the repairs may be extensive, flights may be canceled, which results in significant economic impacts for the aircraft operator as the aircraft may be grounded and taken out of service to be ferried or towed to a maintenance base.

[0005] Automated systems are needed to quickly repair and return large composite structures (e.g., aircraft and wind turbine blades) to service after planned structural maintenance or after an event that may have produced damage (e.g., lightning strike, physical impact, bird strike). Summary of the Invention

[0006] The subject matter of the present disclosure, which will be described in some detail below, is directed to a method and apparatus for performing repair operations using an unmanned aerial vehicle (UAV). The method is made possible by equipping a UAV with tools for quickly repairing large structures or objects (e.g., aircraft or wind turbine blades) that are not easily accessible to maintenance personnel. Multiple tools are available and are selected and deployed to the repair site by a robot. The tools are designed to perform each repair operation in sequence according to a specified repair plan. The plan may take into account the results of previously performed UAV-enabled inspections.

[0007] According to some embodiments, the apparatus includes a UAV equipped with a multi-tool module having a number of tools for performing various functions attached to the distal ends of respective angularly distributed support arms extending outward from a rotatable hub. The various tools can be applied to the repair site in sequence. When a repair procedure requires the use of a particular tool, the hub rotates to bring the designated tool to an angular position that overlaps the repair site. According to one embodiment, the tool is rotated to a position that overlaps and is in contact with or adjacent to the repair site. According to another embodiment, the tool is first rotated to a position that overlaps the repair site and then lowered to contact or adjacent to the repair site.

[0008] According to another embodiment, the apparatus includes a UAV equipped with a rotatable tool pick-and-place robot arm and a number of tools stored in respective tool stations within reach of the rotatable tool pick-and-place robot. A controller is configured to cause the tool pick-and-place robot to rotate to a first angular position, pick up the tool, then rotate to a second angular position while carrying the tool, and place the tool in contact with or proximate to the repair site to perform the repair operation. According to an alternative embodiment, the tools are stored in respective tool stations on the ground and the UAV is equipped with a gripper or clamp (e.g., a collet) that enables the UAV to pick up the tool and then fly to the repair site while carrying the tool.

[0009] Various embodiments of methods and apparatus for repairing structures or objects using a tool-equipped UAV are described in some detail later in this specification, one or more of which may be characterized by one or more of the following aspects.

[0010] One aspect of the subject matter disclosed in detail below is an apparatus including an unmanned aerial vehicle and a multi-tool module coupled to the unmanned aerial vehicle: (a) the unmanned aerial vehicle includes a body frame, a plurality of rotor motors attached to the body frame, and a plurality of rotors operably coupled to respective rotor motors of the plurality of rotor motors, and (b) the multi-tool module includes a hub rotatable about an axis of rotation, a plurality of arms having respective first ends fixedly coupled to the hub, a plurality of tools attached to respective second ends of each of the plurality of arms, and a motor operably coupled to drive rotation of the hub.

[0011] According to some embodiments of the device described in the immediately preceding paragraph, the multi-tool module further comprises a base, an inner cylinder rotatable relative to the base, and a capping head covering the top of the inner cylinder. In one embodiment, the capping head is translatable relative to the top of the inner cylinder, and a number of arms are fixedly coupled to the capping head. In another embodiment, a number of arms are rotatably coupled to the capping head. The arms may be driven to rotate by a linked ring translating along the inner cylinder or by respective linear actuators.

[0012] Another aspect of the subject matter disclosed in detail below is an apparatus including an unmanned aerial vehicle and a tool pick and place module coupled to the unmanned aerial vehicle: (a) the unmanned aerial vehicle includes a body frame, a plurality of rotor motors mounted to the body frame, and a plurality of rotors operably coupled to respective rotor motors of the plurality of rotor motors, (b) the tool pick and place module includes a platform with a plurality of tool stations, a tool pick and place robot mounted to the platform, and a plurality of tools disposed at the respective tool stations, and (c) the tool pick and place robot includes a base, a hub rotatable about the base, an arm having a first end fixedly coupled to the hub and a second end spaced from the hub, and a tool holder attached to the second end of the arm.

[0013] A further aspect of the subject matter disclosed in detail below is an apparatus including an unmanned aerial vehicle and a collet module coupled to the unmanned aerial vehicle. The unmanned aerial vehicle includes a body frame, a plurality of rotor motors attached to the body frame, and a plurality of rotors operably coupled to respective rotor motors of the plurality of rotor motors, the collet module including a collet configured to transition between a clamped state and a non-clamped state. During performance of a repair operation, the apparatus further includes a tool including a mounting post that is clamped by the collet in the clamped state. The tool is selected from a group of tools including a subtractive repair tool, an additive repair tool, a cleaning tool, and a drying tool.

[0014] Yet another aspect of the subject matter disclosed in detail below is a method for repairing a structure using an unmanned aerial vehicle with a collet, the method including: (a) storing first and second tools, each with a respective mounting post, at a ground station, (b) flying the unmanned aerial vehicle to a first position where the collet is aligned with the mounting post of the first tool, (c) closing the collet to clamp the mounting post of the first tool, (d) flying the unmanned aerial vehicle toward the structure to be repaired with the first tool subordinate to the unmanned aerial vehicle, (e) landing the unmanned aerial vehicle on a surface of the structure, and (f) performing a first repair operation on an area on the surface of the structure using the first tool while the unmanned aerial vehicle is parked on the surface of the structure. (g) flying the unmanned aerial vehicle to a first position; (h) opening the collet to release the mounting post of the first tool; (i) flying the unmanned aerial vehicle to a second position where the collet is aligned with the mounting post of the second tool; (j) closing the collet to clamp the mounting post of the second tool; (k) flying the unmanned aerial vehicle having a second tool subordinate to the unmanned aerial vehicle toward the structure; (l) landing the unmanned aerial vehicle on the surface of the structure; and (m) performing a second repair operation on an area on the surface of the structure using the second tool while the unmanned aerial vehicle is parked on the surface of the structure.

[0015] Other aspects of methods and apparatus for repairing structures or objects using a tool-equipped UAV are disclosed below.

[0016] The aforementioned features, functions, and advantages may be implemented individually in various embodiments or may be combined in yet other embodiments. To illustrate the foregoing and other aspects, various embodiments are described below with reference to the drawings. None of the drawings briefly described in this section are drawn to scale. [Brief description of the drawings]

[0017] [Figure 1A] 1A and 1B form a flowchart identifying steps of a method for inspecting and repairing damaged portions of a large structure or object using one or more UAVs, according to some embodiments. [Figure 1B] 1A and 1B form a flowchart identifying steps of a method for inspecting and repairing damaged portions of a large structure or object using one or more UAVs, according to some embodiments. [Diagram 2] FIG. 2 depicts a side view of a UAV carrying a payload, according to one embodiment. [Figure 2A] FIG. 3 depicts a side view of the UAV carrying the payload depicted in FIG. 2 after landing on a structure having a rounded surface, such as an aircraft fuselage or a storage tank. [Figure 2B] FIG. 3 depicts a side view of the UAV carrying a payload depicted in FIG. 2 after landing on an airfoil-shaped body, such as an aircraft wing or a wind turbine blade. [Figure 3A] 3A through 3D are diagrams representing respective three-dimensional views of a UAV having a pivotable arm for carrying a payload at successive stages in the process of transporting and placing the payload on the surface of a repairable structure. [Figure 3B] 3A through 3D are diagrams representing respective three-dimensional views of a UAV having a pivotable arm for carrying a payload at successive stages in the process of transporting and placing the payload on the surface of a repairable structure. [Figure 3C] 3A through 3D are diagrams representing respective three-dimensional views of a UAV having a pivotable arm for carrying a payload at successive stages in the process of transporting and placing the payload on the surface of a repairable structure. [Figure 3D] 3A through 3D are diagrams representing respective three-dimensional views of a UAV having a pivotable arm for carrying a payload at successive stages in the process of transporting and placing the payload on the surface of a repairable structure. [Figure 4] 3A depicts a top view of a multi-tool module, which may be a payload carried by a UAV of the type depicted in FIG. 2 or FIG. 3A or of a type having a different design, according to one embodiment. [Figure 4A] FIG. 5 depicts a side view of some components of the multi-tool module depicted in FIG. 4 (with the tools omitted). [Diagram 5] 5 depicts a top view of a tool pick and place module with a pick and place robot and a tool station platform, according to one embodiment. The module can be a payload carried by a UAV of the type depicted in FIG. 2 or FIG. 3A or of a type having a different design. In the situation depicted in FIG. 5, the pick and place robot is carrying one tool towards the anomaly while the other tools remain in their respective tool stations on the platform. [Figure 5A] FIG. 5A depicts a side view of a tool pick and place robot of the type depicted in FIG. 5. The tool engagement arm (shown in an angular position out of the page) is rotatable 360 ​​degrees and vertically displaceable between an uppermost and a lowermost position. The tool engagement arm is shown in FIG. 5A in its uppermost position, with vertical displacement indicated by a double arrow. [Figure 5B] FIG. 13 depicts a side view of the tool pick and place robot with the arm in its lowest position and engaged with a tool placed in the tool station. [Figure 6A] 6A and 6B are respective portions of a flowchart identifying steps of a method for inspecting and repairing damaged portions of a structure or object using a UAV having a tool pick-up and place robot of the type depicted in FIGS. 5A and 5B. [Figure 6B]6A and 6B are respective portions of a flowchart identifying steps of a method for inspecting and repairing damaged portions of a structure or object using a UAV having a tool pick-up and place robot of the type depicted in FIGS. 5A and 5B. [Figure 7] FIG. 1 is a block diagram identifying several components of a system for inspecting and repairing structures using a UAV equipped with multiple tools that can be individually deployed in sequence as planned via control of a motorized hub. [Figure 8] FIG. 1 is a block diagram identifying several components of a motorized hub according to one embodiment, including an inner cylinder rotatable relative to the base, and a capping head carrying a tool translatable relative to the inner cylinder. [Figure 9] FIG. 1 is a block diagram identifying several components of a system for holding a UAV in a stable position on a surface of a structure using suction cups. [Figure 10A] 10A and 10B are side views of a multi-tool module with retractable tool-carrying arms according to an alternative embodiment. The module can be a payload carried by a UAV of the type depicted in FIG. 2 or 3A or of a different design. The multi-tool module is shown in two states: with the tool-carrying arms extended (see FIG. 10A) and with the tool-carrying arms retracted (see FIG. 10B). [Figure 10B] 10A and 10B are side views of a multi-tool module with retractable tool-carrying arms according to an alternative embodiment. The module can be a payload carried by a UAV of the type depicted in FIG. 2 or 3A or of a different design. The multi-tool module is shown in two states: with the tool-carrying arms extended (see FIG. 10A) and with the tool-carrying arms retracted (see FIG. 10B). [Figure 11]11 depicts a side view of a multi-tool module having a retractable tool carrying arm according to another embodiment, the tool carrying arm being shown in an extended position. [Figure 12] 13 depicts a top view of a tool held by a collet module being carried toward an anomaly on the surface of a structure while other tools are located at respective tool stations on the ground. The collet module may be a payload carried by a UAV of the type depicted in FIG. 2 or FIG. 3A or of a type having a different design. [Figure 12A] FIG. 13 depicts a side view of the collet module engaged with the tool depicted in FIG. 12. [Figure 13A] 13A and 13B are respective portions of a flowchart identifying steps of a method for inspecting and repairing damaged portions of a structure or object using a UAV having a collet module of the type depicted in FIG. 12A. [Figure 13B] 13A and 13B are respective portions of a flowchart identifying steps of a method for inspecting and repairing damaged portions of a structure or object using a UAV having a collet module of the type depicted in FIG. 12A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Reference will now be made to the drawings, in which similar elements in different drawings are given the same reference numbers.

[0019] For illustrative purposes, a method and apparatus for inspecting and repairing a structure or object using a tool-equipped UAV will now be described in detail. However, not all features of an actual implementation are described herein. Those skilled in the art will appreciate that the development of such an embodiment will require the exercise of numerous implementation-specific judgments to achieve the developer's particular objectives, such as adhering to system-related constraints, business-related constraints, etc., which may vary from implementation to implementation. It will further be appreciated that such a development effort may be complex and time-consuming, but is a routine undertaking for those skilled in the art having the benefit of this disclosure.

[0020] As used herein, the term "structure" is not limited to aircraft and wind turbines. The present disclosure relates to systems and methods that may be used to inspect and repair any number of parts or structures of various shapes and sizes, such as machined forgings, castings, pipes, or composite panels or parts. Additionally, the inspected and repaired structures may include various components, such as substructures to provide additional support to the structure. Additionally, the inspected and repaired structures may be made from any one of several materials. For example, the inspected and repaired structures may include metallic materials, such as aluminum, or composite materials, such as graphite epoxy. In particular, the inspected and repaired structures may be aircraft components made from composite materials.

[0021] According to embodiments disclosed in some detail below, the UAV takes the form of a rotorcraft having multiple rotors. According to embodiments disclosed herein, each rotor has two mutually radially opposed blades. However, in alternative embodiments, UAVs having three or more rotor blades may be used. As used herein, the term "rotor" refers to a rotating device including a rotor mast, a rotor hub attached to one end of the rotor mast, and two or more rotor blades extending radially outward from the rotor hub. In embodiments disclosed herein, the rotor mast is mechanically coupled to an output shaft of a drive motor, referred to herein as a "rotor motor." The rotor motor drives the rotation of the rotor. As used herein, the term "rotor system" refers to a combination of components including at least multiple rotors and a controller configured to control the rotational speed of the rotors to generate sufficient aerodynamic lift to support the weight of the UAV and sufficient thrust to counteract aerodynamic drag in forward flight. The UAV disclosed herein preferably includes a controller in the form of a multiple rotor motor controller in communication with an on-board computer configured to coordinate the rotation of each of the rotors. The controller is configured (e.g., programmed) to control the rotors to fly the UAV along a flight path to a location where the UAV is in proximity to or in contact with an area on the surface of the structure to be inspected and repaired. (As used herein, the term "location" includes a position in a three-dimensional coordinate system and an orientation relative to that coordinate system.)

[0022] According to various embodiments of the processes proposed herein, the UAV is configured to perform repair operations in a manner that allows large structures, such as aircraft or wind turbines, to be quickly returned to service after an impact event or discovery of potential damage. According to some embodiments, the UAV is equipped with means for collecting information (e.g., images, scans, and three-dimensional (3D) position data) that may indicate the presence of an anomaly.

[0023] 1A and 1B form a flow chart identifying steps of a method 100 for inspecting and repairing damaged portions of a large operational structure or object using one or more UAVs. As will be described in more detail below, a computer on board the UAV may be configured to determine whether the acquired data indicates damage greater than (above) or less than (below) a particular threshold. As used herein, a "use as is" threshold refers to a threshold designated to demarcate between a structure that does not require repair (e.g., when the damage indicated is less than or below the "use as is" threshold) and a structure that potentially requires repair (e.g., when the damage indicated is greater than or above the "use as is" threshold). As used herein, a "remote repair" threshold refers to a threshold designated to demarcate between a structure that requires repair that can be performed by a UAV (e.g., when the damage indicated is less than or below the "remote repair" threshold) and a structure that requires repair that is not performed by a UAV (e.g., when the damage indicated is greater than or above the "remote repair" threshold).

[0024] 1A, method 100 begins 102 when an operational structure is functional but either a scheduled time has been reached for a planned operational inspection (step 104) or potential damage from an incident to the operational structure has been indicated or inferred (step 106). For example, an object collision event has been detected or inferred.

[0025] The entire inspection and repair process begins when the maintenance operations center dispatches a camera-equipped UAV to perform a visual inspection of the structure in service (step 108). The dispatched UAV flies in the vicinity of the estimated impact area (hereinafter the "area of ​​interest"), uses the camera to acquire images of the area of ​​interest, and then compares the acquired image data to a first "use as is" threshold (step 110). The results of the visual inspection and comparison to the threshold, the location of the imaged area, and other data are then recorded in a non-transitory, tangible, computer-readable storage medium on board the camera-equipped UAV (step 112). A computer on board the camera-equipped UAV then makes a determination whether the damage indicated by the image data is above the first "use as is" threshold (step 114). Alternatively, if the camera-equipped UAV is not also equipped with an NDI sensor unit, the camera-equipped UAV wirelessly transmits data representing the results of the visual inspection and comparison to the threshold, data representing the location of the imaged area, and other data to a maintenance operations center for evaluation.

[0026] On the other hand, if a determination is made in step 114 that the damage indicated by the image data is not above the first "use as is" threshold, the structure is used as is (step 116) and returned to service (step 140 of FIG. 1B). On the other hand, if a determination is made in step 114 that the damage indicated by the image data is above the first "use as is" threshold, a UAV equipped with an NDI sensor unit (which may be the same UAV equipped with the camera or a different UAV) is flown to a location where the NDI sensor unit is within measurement range of a potentially damaged area on the surface of the structure (hereinafter the "potential damage area"). For example, the NDI sensor equipped UAV may land on the surface of the structure and then use the NDI sensor unit to acquire NDI sensor data within the potential damage area (step 118). A computer on board the NDI sensor equipped UAV then performs an analysis of the NDI sensor data to quantify the subsurface damage and compares the resulting quantitative data to various predefined thresholds (step 120). The results of the analysis and comparison to the thresholds, the location of the detected area, and other data are then recorded in a non-transitory, tangible, computer-readable storage medium on board the NDI sensor-equipped UAV (step 122). The computer on board the NDI sensor-equipped UAV then determines whether the damage indicated by the NDI sensor data is above a second "use as is" threshold (step 124). Alternatively, if the NDI sensor-equipped UAV is not further equipped with a repair tool, the NDI sensor-equipped UAV wirelessly transmits data representing the results of the analysis and comparison to the thresholds, the location of the detected area, and other data to a maintenance operations center for evaluation.

[0027] On the other hand, if a determination is made in step 124 that the damage indicated by the NDI sensor data is not above the second "use as is" threshold, the structure is used as is (step 116) and returned to service (step 142 in FIG. 1B). On the other hand, if a determination is made in step 124 that the damage indicated by the NDI sensor data is above the second "use as is" threshold, a computer on board the NDI sensor-equipped UAV makes a determination whether the damage indicated by the NDI sensor data is below a "remote repair" threshold (step 126). Alternatively, if the NDI sensor-equipped UAV is not further equipped with a repair tool, the maintenance operations center has a computer programmed to make the determination in step 126.

[0028] Depending on the outcome of step 126 (shown in FIG. 1A), the process may proceed according to either a remote or UAV-enabled repair procedure or a manual repair procedure requiring human intervention. Both of these steps are identified in FIG. 1B. On the other hand, if a determination is made in step 126 that the damage indicated by the NDI sensor data is not above the “remote repair” threshold, then a UAV equipped with a repair tool (which may be the same UAV equipped with a camera or a different UAV) is flown to a position where the repair tool is positioned to contact the structure in the area to be repaired. While the UAV equipped with a repair tool is stationary, the damaged area is repaired using the repair tool (step 128 in FIG. 1B). On the other hand, if a determination is made in step 126 that the damage indicated by the NDI sensor data is above the “remote repair” threshold, then the UAV equipped with an NDI sensor wirelessly transmits a message informing the maintenance operations center that the structure requires direct human access for a more thorough or complex repair of the damaged structure (step 134). In the latter case, possible repairs will not be carried out by the UAV.

[0029] Still referring to FIG. 1B, after completion of the possible repairs by the UAV in step 128, a UAV equipped with either a camera or an NDI sensor unit (which may be the same UAV as the camera-equipped or NDI sensor-equipped UAV described above or a different UAV) is used to perform an inspection to verify that the repaired structure is OK for service (step 130). The results of the inspection are stored in a non-transient tangible computer-readable medium on board the inspecting UAV, and the UAV wirelessly transmits a message to the maintenance and operations center reporting the completion of the repairs. A determination is then made whether the repairs are valid (step 132). On the other hand, if the repairs are not valid, the repair procedure returns to step 128. On the other hand, if the repairs are valid, the repaired structure is returned to service (step 140).

[0030] Conversely, after a notification is issued indicating that a non-UAV-based repair (e.g., manual repair) is recommended, the maintenance operations center dispatches a suitably equipped technician to repair the damaged area on the structure (step 134). After the non-UAV-based repair in step 134 is completed, an NDI or visual inspection of the repaired portion of the structure is performed (step 136), also by non-UAV-based means. A determination is then made whether the repair is valid (step 138). On the other hand, if the repair is not valid, the repair procedure returns to step 134. On the other hand, if the repair is valid, the repaired structure is returned to service (step 140).

[0031] Various embodiments of apparatus for performing repairs (step 128) to damaged areas on the surface of a structure will be described in some detail below. Tools and tool support devices carried by the UAV may be referred to herein as "payloads." Such repair payloads may be fixedly or pivotally coupled to a body frame of the UAV, or may be fixedly coupled to a payload support frame that is pivotally coupled to the UAV body frame. Some of the repair payloads disclosed herein are referred to herein as modules. As used herein, the term "module" refers to an independently operable unit that may be attached to a UAV and comprises an assembly of electrical and mechanical components configured to perform a repair function using the repair matter.

[0032] The UAV disclosed herein preferably includes a controller in the form of a plurality of rotor motor controllers in communication with an on-board computer system configured to coordinate the rotation of each of the rotors. The controller is configured (e.g., programmed) to control the rotors according to flight guidance received from a 3D localization system that tracks the position of the UAV relative to the target environment. The target destination of the UAV is a location where a plurality of standoff contact elements of the UAV contact the surface of a structure to be repaired (hereinafter, "repairable structure"). When the standoff contact elements contact the surface of the repairable structure, the controller activates a surface mounting device (e.g., a vacuum suction device) to maintain the UAV stationary in that position with the standoff contact elements abutting the surface. Repair tools are then positioned and activated in sequence to perform the respective repair operations. Upon completing the repair procedure, the UAV releases the surface mounting device and takes off from the surface, again using the direction and speed changes by a portion of the rotor.

[0033] 2 carries a payload 6 that includes one or more tools for performing repair functions on the surface of a remote, limited-access structure. According to some embodiments described in some detail below, the payload 6 is a multi-tool module with multiple tools. According to another embodiment described in some detail below, the payload 6 is a collet module that includes a collet that holds a single tool.

[0034] As seen in FIG. 2 , the UAV 2 includes a body frame 4, a plurality of rotor motors 12 mounted to the body frame 4, and a plurality of rotors 10 operatively coupled to the plurality of rotor motors 12, respectively. Additionally, the UAV 2 includes a payload support frame 8 pivotally coupled to the body frame 4 by a gimbal pivot 14. The payload support frame 8 includes a plurality (at least three) of spaced apart support members 18. A respective spaced apart contact lower portion 16 is coupled to a distal end of each spaced apart support member 18. In one proposed embodiment, the spaced apart contact lower portions 16 are made of a compliant (e.g., elastic) material. The spaced apart support members 18 and the spaced apart contact lower portions 16 form a standoff system that maintains the payload 6 in a spaced apart position relative to the surface being repaired.

[0035] According to the embodiment depicted in FIG. 2, the spaced lower parts 16 are pivotally coupled to the distal ends of the spaced support members 18 by respective pivots 20. The pivotal coupling allows the spaced lower contact parts 16 to adjust their orientation so that the lower parts lie flat on a curved surface. FIG. 2A shows a UAV 2 carrying a payload after landing on a target object 1 having a surface 9, such as the surface of an aircraft fuselage or the top surface of a storage tank. FIG. 2B shows the same UAV 2 after landing on the surface 9 of an airfoil-shaped body 11, such as an aircraft wing or a wind turbine blade. In both scenarios, each spaced lower contact part 16 can be reoriented flat or tangentially parallel to the curved surface 9 in the area of ​​abutment.

[0036] 3A-3D are diagrams representing three-dimensional views of a UAV 2 having a pivotable arm 3 (hereinafter "arm 3") for carrying a payload 6 at successive stages in the process of transporting and placing the payload 6 on a surface 9 of a repairable structure. The arm 3 is pivotally coupled to a body frame 4 of the UAV 2 by a pivot 5 supported by a pivot support frame 4a. The pivot support frame 4a is attached to or integrally formed with the body frame 4. The payload 6 is coupled to one end of the arm 3 by a coupling mechanism 15 (visible in FIG. 3D). A counterweight 7 is coupled to the other end of the arm 3. The payload 6 and the counterweight 7 have respective known weights. Controlling the arm 3 to align the payload 6 with a portion of the surface 9 includes controlling the arm 3 with respect to one or more parameters. In particular, controlling the angular position of the arm 3 may be based on the length of the arm, the fulcrum (at the pivot 5), the counterweight, and the weight of the payload. Controlling the angular position of the arm 3 based on these factors may prevent the UAV 2 from substantially pitching or rolling when aligning the payload 6 with the portion of the surface 9 to be contacted by the payload 6. The position (location and orientation) of the pivot 5 relative to the surface 9 may be adjusted by adjusting the position of the UAV as it hovers near the surface 9 until the payload 6 lands on the surface 9. The angular position of the arm 3 relative to the body frame 4 of the UAV 2 may also be adjusted during flight. FIG. 3B depicts the UAV 2 flying toward the surface 9 while the arm 3 is oriented generally horizontally. Changing the angle of the arm 3 may be accomplished using a motor (not shown in FIGS. 3A-3D) mounted on the pivoting support frame 4a and operably coupled to the arm 3 by a gear train (not shown in FIGS. 3A-3D), or using a linear actuator (not shown in FIGS. 3A-3D) with one end connected to the pivoting support frame 4a and the other end connected to the arm at a point spaced from the pivot 5. FIG. 3C depicts the stage where the payload 6 is lying flat against the surface 9 of the repairable structure.3D depicts the stage in which the UAV 2 is flying away from the surface 9 after the payload 6 has been decoupled from the arm 3 while in the state depicted in FIG. 3C. The decoupled payload 6 may remain attached to the surface 9 due to attachment forces applied by a number of surface attachment devices (not shown in FIGS. 3A-3D), such as magnetic-based devices (e.g., electric permanent magnets) for ferromagnetic structures, and / or vacuum-, electrostatic-, adhesive-, or gripping-based devices for non-ferromagnetic structures.

[0037] A UAV2 carrying a payload as depicted in FIG. 2 or FIG. 3A is equally well suited for repairing a wide range of structures, including, but not limited to, aircraft, wind turbine blades, storage tanks, power lines, power plants, power grids, dams, levees, stadiums, large buildings, bridges, large antennas and telescopes, water treatment plants, refineries, chemical processing plants, high-rise buildings, and infrastructure related to train and monorail support structures. The system is also particularly well suited for use inside large buildings such as manufacturing facilities and warehouses. Virtually any structure that may be difficult, expensive, or very dangerous to repair by a human controlling a repair tool can potentially be repaired using the system described herein. Various embodiments of repair payloads carried by UAV2 will be described in some detail below.

[0038] According to one embodiment of a method for UAV-enabled repair of a structure or target object with limited access, a UAV equipped with a multi-tool, disclosed in some detail below, is designed to land on the surface of the structure in a position such that UAV2 is in the vicinity of the damaged area. A first repair tool is then moved into position and activated to perform a first repair operation. Once the first repair operation is completed, the first repair tool is moved away and a second repair tool is moved into position and activated to perform a second repair operation. This process may continue until the Nth operation (of a scheduled sequence consisting of N repair operations) is completed, where N is an integer equal to or greater than 3. UAV2 then lifts off the surface and returns to the home base.

[0039] Figure 4 depicts a top view of a multi-tool module 60a according to one embodiment, which may be a payload 6 carried by a UAV 2 of the type depicted in Figure 2 or 3A or of a different design. The multi-tool module 60a includes a hub 62 rotatable about an axis of rotation (hereinafter "hub axis of rotation") and a hub motor (not shown in Figure 4) operably coupled to drive rotation of the hub 62 (indicated by the arrow in Figure 4).

[0040] The multi-tool module 60a further includes a plurality of tools coupled to the hub 62 by a plurality of linear arms 64a-d extending radially outwardly at right angles to the hub axis of rotation. Thus, the tools rotate about the hub axis of rotation when the hub 62 and the arms 64a-d are rotated. The arms 64a-d may be distributed at equal angular intervals. In the embodiment depicted in FIG. 4, the multi-tool module 60a includes four arms 64a-d (disposed at 0, 90, 180, and 270 degrees) and four tools attached to the distal end of each arm 64a-d. The four tools include a sander or other removal repair tool (hereinafter removal repair tool 68) attached to arm 64a, an additional repair tool 70 attached to arm 64b, a drying tool 72 attached to arm 64c, and a cleaning tool 74 attached to arm 64d. As used herein, the term "subtractive repair tool" refers to a tool configured to remove material from a body of material, while the term "additive repair tool" refers to a tool configured to add material to a body of material.

[0041] The multi-tool module 60a further includes attachment points 66, which may be integrally formed with or attached to the capping head 76. The attachment points 66 are coupled to the payload support frame 8 during flight of the UAV 2 (see FIG. 2) and may be decoupled from the UAV 2 after the multi-tool module 60a has been delivered to the repair site and attached or glued.

[0042] FIG. 4A is a diagram depicting a side view of the hub 62 (tool omitted) of the multi-tool module 60a depicted in FIG. 4. The hub 62 is shown rotatably mounted to a base 80 of the multi-tool module 60a. The hub 62 is rotatable relative to the base 80 about an axis of rotation (hereinafter the "hub axis of rotation"). The hub 62 includes a first hub motor (not visible in FIGS. 4 and 4A, but see hub motor 26 in FIG. 7) operably coupled to drive rotation of the hub 62 (indicated by the arrow in FIG. 4). More specifically, the hub 62 includes an inner cylinder 78 rotatable relative to the base 80, and a capping head 76 that caps a top portion of the inner cylinder 78. The capping head 76 is translatable up and down relative to a top portion of the inner cylinder 78, as indicated by the double arrow in FIG. 4A. For example, the shroud head 76 may be slidably coupled to the inner cylinder 78 by a plurality of linear slides disposed at equal angular intervals between a cylindrical portion of the shroud head 76 and a top of the inner cylinder 78 and parallel to the hub axis of rotation. The hub 62 further includes a second hub motor (not visible in FIGS. 4 and 4A, but see hub motor 26 in FIG. 7) operably coupled to drive the translational movement of the shroud head 76. The plurality of arms 64a-d have respective first ends fixedly coupled to the shroud head 76, and a plurality of tools are attached to respective distal (second) ends of the plurality of arms 64a-d.

[0043] The arms 64a-64d carrying tools attached to and extending radially outward from the capping head 76 are lifted, rotated and lowered into position over the repair area according to a planned sequence determined by the nature of the repair. The arms 64a-64d may optionally be spring-loaded relative to the capping head 76 to apply downward pressure when the capping head 76 is lowered to a height where the tools contact the surface. Since the vertical control at the mounting ends of the arms 64a-64d is not independent, the tools not in use may at least contact the skin of the structure in the unrepaired position. Since the tools are lifted during each rotation, no scratching or other surface damage will occur. This is the purpose of the vertical actuation of the capping head 76. Since the primary purpose of the vertical movement of the capping head 76 is to avoid dragging the tools on the surface, only a small range of movement is sufficient.

[0044] The hub motor 26 may operate under computer control to rotate the first selected tool to a position vertically aligned with the damaged area and then lower the first selected tool to a position proximate the damaged area. (It should be understood that during rotation or translation of any one of the four tools attached to the hub 62, the other three tools rotate or translate vertically in unison.) While in the proximate position, the first selected tool may then be activated to perform the first repair operation. When the first repair operation is completed, the hub motor 26 may operate under computer control to lift all the tools and then rotate the first selected tool away from the vertically aligned position. While the first selected tool is being rotated away from the vertically aligned position, the second selected tool is rotated towards the vertically aligned position. The second selected tool is then lowered to the proximate position and activated to perform the second repair operation. The repair procedure may continue until completed by applying additional tools to the damaged area in succession by similar rotation and vertical translation of the capping head 76 and arms 64a-64d.

[0045] According to one typical repair operation, the first removal repair tool 68 is moved into position to remove material from the damage site. Then, the cleaning tool 74 is moved into position to direct a pulse of compressed gas to clear any loose material on or around the area to be repaired. Next, the additional repair tool 70 is moved into position to apply a curable material onto the damaged area. Finally, the drying tool 72 is moved into position to apply heat to harden the curable material. In one proposed embodiment, the removal repair tool 68 is a grinder and the additional repair tool 70 is a repair material applicator, such as a sprayer. For example, the removal repair tool 68 can include a rotating shaft (not shown in the drawings) with an abrasive head for grinding or scraping the damaged surface of the structure to prepare the surface for the addition of a coating material. The rotating shaft is driven to rotate by a rotary tool motor. The additional repair tool 70 includes a pump (not shown in the drawings) that draws liquid material up through a tube and out of a nozzle, dropping onto the surface of the structure in the damaged area. The pump draws liquid from the reservoir when the pump motor is activated, through an open electric control valve, through a tube, and out of a nozzle. The drying tool 72 may include a heat source used to dry the surface prior to processing or to harden the correction material applied by the additional repair tool 70. The cleaning tool 74 may include a pressurized reservoir, an electromechanical control valve, and a nozzle for directing a pulse of compressed gas to clear any loose material on or around the area being repaired. According to one embodiment, each motorized tool receives power from a battery onboard the UAV 2 through respective wires that emanate from a common umbilical cable (not shown in Figures 3A and 3B). In alternative embodiments, the multi-tool module 60a may include two, four, or more tools. Regardless of the number of tools arrayed around the shroud head 76, the projections of the arms on a plane perpendicular to the hub rotation axis may be distributed at equal angular intervals.

[0046] FIG. 5 is a diagram depicting a top view of the pick and place module 22 according to one embodiment. The module may be a payload 6 carried by a UAV 2 of the type depicted in FIG. 2 or FIG. 3A or of a different design. The tool pick and place module 22 includes a tool pick and place robot 82, a platform 84 with a number of tool stations 88, and a number of tools arranged at the respective tool stations 88. The number of tools may include a removal and repair tool 68, an additional repair tool 70, a drying tool 72, and a cleaning tool 74 (which tools have been described in some detail above). In the state depicted in FIG. 5, the removal and repair tool 68 has been removed from its assigned tool station 88, thereby making that tool station visible. The tool stations assigned to the other tools 70, 72, and 74 are covered by the tools still occupying the stations and are not visible in FIG. 5. The number of tool stations 88 are arranged at respective angularly distributed positions on the platform 84 within a circular cylindrical reference frame centered on the axis of rotation of the tool pick and place robot 82. According to one embodiment, the tool pick and place robot 82 is mounted to an upper portion of the payload support frame 8, while the platform 84 is mounted to the spaced apart support members 18 (see FIG. 2).

[0047] The tool pick and place robot 82 includes a hub 62, a hub motor (not shown here in FIG. 5) for driving rotation of the hub 62 about the hub axis of rotation, and a tool engagement arm 86 (hereinafter "arm 86") having a first end fixedly coupled to the hub 62 and a second (distal) end spaced from the hub 62. The second end of the arm 86 incorporates a tool holder (not shown in FIG. 5) for holding the tool during movement of the tool. A number of tools stationed at a number of tool stations 88 on the platform 84 are located, at least in part, within the length of the arm 86 of the tool pick and place robot 82. In the situation depicted in FIG. 5, a removal repair tool 68 is held by the tool holder as the tool pick and place module 22 rotates the removal repair tool 68 toward an anomaly 99 found on the surface of the structure being repaired.

[0048] FIG. 5A is a diagram depicting a side view of the tool pick and place robot 82 depicted in FIG. 5. As previously described with reference to FIG. 4A, the hub 62 includes an inner cylinder 78 that is rotatable relative to the base 80, and a covering head 76 that is translatable up and down relative to the inner cylinder 78. The arm 86 is positioned in an angular position that goes out of the page. Thus, only the end face of the arm 86 is visible in FIG. 5. One end of the arm 86 is attached to or integrally formed with the covering head 76. Thereby, the arm 86 rotates and translates as the covering head 76 rotates and translates. The arm 86 may be rotatable 360 ​​degrees and may be vertically displaceable between a highest position and a lowest position. The arm 86 is shown in its highest position in FIG. 5A, with the vertical displacement indicated by the double arrow.

[0049] Figure 5B depicts a side view of the tool pick and place robot 82 with the arm 86 in a lowest position and engaged with a tool 24 seated in a tool station on the platform 84. The tool 24 may be any one of the tools depicted in Figure 5 or any other tool. The tool engaged state depicted in Figure 5B may occur when the tool pick and place robot 82 picks up or drops off a tool 24 from or to an assigned tool station 88.

[0050] According to the embodiment depicted in Figure 5B, the arm 86 of the tool pick and place robot 82 incorporates a tool holder in the form of an electromagnet or electric permanent magnet (collectively referred to herein below as "electromagnets 90"). Additionally, the tool 24 includes a permanent magnet 92 positioned to be magnetically coupled to the electromagnet 90 when the arm 86 is lowered into contact with the tool 24. Each tool 24 on the platform 84 incorporates a permanent magnet 92. The magnetic coupling force may be controlled by varying the power supplied to the electromagnet 90.

[0051] Electro-permanent magnets are solid-state devices that have zero static power consumption (like permanent magnets) but can be switched on and off like electromagnets. Power only needs to be applied for a short moment to switch the state either on or off, which advantageously makes them more useful in applications where overall power usage is low. The use of electro-permanent magnets also has the advantage that the coupling is still effective even if power is lost. While the electro-permanent magnet approach requires a power source, electro-permanent magnets may only need to be powered for a short moment to switch the magnetic field state. According to an alternative embodiment, the tool holder of the tool pick and place robot 82 may be a vacuum gripper or a mechanical clamp. In these cases, the tool 24 does not need a dedicated means to interact with the tool holder of the tool pick and place robot 82. According to one embodiment, the tool receives power from a battery pack on board the UAV 2 via the tool pick and place robot 82. This configuration allows the tool to have a lighter weight. According to an alternative embodiment, the tool may have a separate battery pack built-in.

[0052] 6A and 6B are respective portions of a flowchart identifying steps of a method 200 for inspecting and repairing damaged portions of a structure or object using a UAV having a tool pick-and-place robot 82 of the type depicted in FIGS. 5A and 5B. Referring to FIG. 6A, the method 200, according to one embodiment, includes selecting N tools (where N is a positive integer equal to or greater than 1) for performing a repair procedure on a surface of the structure (step 202), and then placing the selected N tools at respective tool stations on a platform coupled to the UAV at a ground base (step 204). The UAV then takes off from the ground base (step 206) and flies toward the structure to be repaired (also referred to herein as a "repairable structure") (step 208), with the tool pick-and-place robot, the platform, and the N tools as payloads attached to the UAV. The UAV then lands on the surface of the structure (step 210). While the UAV is parked on the surface of the structure, the arm of the tool pick and place robot is moved into position over the tool station of the first tool to be used (step 212). The arm is then lowered into contact with the first tool (step 214) and the tool holder is activated (step 216), thereby coupling the first tool to the arm. The arm is then lifted, rotated, and lowered to transfer the first tool from its tool station to a position in contact with or close to the damage site on the surface (step 218). The first tool is used to perform a first repair operation on the area of ​​the surface requiring repair (step 220). Once the first repair operation is completed, the arm is lifted, rotated, and lowered to transfer the first tool from the damage site back to its tool station (step 222). The arm of the tool pick and place robot is then moved into position over the tool station of the next tool to be used (step 224). The arm is lowered into contact with the next tool (step 226) and then the tool holder is actuated (step 228), thereby coupling the next tool to the arm.The arm is then raised, rotated, and lowered to transfer the next tool from its tool station to a position in contact with or close to the damage site (step 230). The next tool is used to perform the next repair operation on the area being repaired (step 232). Once the next repair operation is completed, the arm is raised, rotated, and lowered to transfer the next tool from the damage site back to its tool station (step 234). The robot controller then determines whether the last operation of the planned repair procedure has been performed (step 236). If a determination is made in step 236 that the last repair operation has not been completed, the process returns to step 224. If a determination is made in step 236 that the last repair operation has been completed, the UAV takes off from the repaired structure (step 238) and then flies back to the ground base (step 240).

[0053] 7 is a block diagram identifying several components of a system for inspecting and repairing structures using a UAV 2 equipped with multiple tools 24 that are individually deployable in a planned sequence via control of the rotation of a hub 62. According to the embodiment depicted in FIG. 7, the UAV 2 is also equipped with a video camera 30 and a non-destructive inspection sensor unit 42 (hereinafter "NDI sensor unit 42"). The UAV 2 has a control system 32 that controls the rotation of the rotor 10, any rotatable components of the tools 24, and the inner cylinder 78 of the hub 62, and further controls the translation of the capping head 76 relative to the inner cylinder 78. The control system 32 also controls the operation of the video camera 30, the NDI sensor unit 42, and other electrically operable components of the tools 24 (such as solenoids).

[0054] More specifically, the control system 32 includes a computer system 36 communicatively coupled to a number of motor controllers 34. The motor controllers 34 are configured to control the rotational speed and direction of the rotor motor 12 (which drives the rotation of the rotor 10), the hub motor 26 (which drives the rotation of the inner cylinder 78 and the translation of the cap head 76), and the tool motor 28 (which drives the rotation or other movement of the tool 24), respectively. The operation of these motors is coordinated by the computer system 36 to perform repair operations in a specific planned sequence. In one proposed embodiment, the motor controllers 34 are electric speed control circuits configured to vary the speed, direction, and braking of electric motors, which are brushless electric motors. Such electric speed control circuits provide high frequency, high resolution, three-phase AC power to the motors.

[0055] If the video camera 30 is mounted on a turret (not shown in FIG. 7), the control system 32 also includes a motor controller for controlling the rotational speed and direction of a camera turret motor (also not shown in FIG. 7). Such a camera turret may be rotatably coupled to a turret base mounted on the body frame 4 of the UAV 2. This allows the video camera 30 to capture respective images during various stages of a remote inspection / repair operation. The images are wirelessly transmitted to a maintenance operations center, thereby allowing maintenance personnel to observe the damaged areas on the structure during NDI and repair operations.

[0056] In the embodiment partially depicted in FIG. 7, the video camera 30 and the NDI sensor unit 42 are controlled by the computer system 36 in response to radio frequency commands transmitted by the control station 40. The radio frequency commands are transmitted by a ground transceiver 44, received by a transceiver 38 on board the UAV 2, and converted by the transceiver 38 into the proper digital format. The resulting digital commands are then forwarded to the computer system 36. The control station 40 may comprise a general-purpose computer system programmatically configured to control the operation of the UAV 2 and the NDI sensor unit 42 on board the UAV 2. For example, the flight of the UAV 2 may be controlled using a joystick, keyboard, mouse, touchpad, or touchscreen, or other user interface hardware (e.g., a gamepad or pendant) of the computer system in the control station 40. Additionally, the computer system in the control station 40 is programmatically configured to process data received from the UAV 2 during inspection operations. In particular, the computer system of control station 40 may include a display processor configured by software to control a display monitor (not shown in FIG. 7) that displays images captured by video camera 30 .

[0057] As previously described, after completion of the non-destructive evaluation, a determination (diagnosis) of whether possible repairs are required may be made by the UAV. In that event, a UAV 2 equipped with an ensemble of tools configured to perform the individual operations included in the planned repair is flown to the damage site on the surface of the structure or object. The UAV operator guides the UAV 2 to place the repair tool 24 on the target area. The UAV equipped with the repair tool may also have a surface mounting device (not shown in FIG. 7), such as a magnetic-based device (e.g., an electric permanent magnet) for ferromagnetic structures and / or a vacuum-based, electrostatic-based, adhesive-based, or gripping-based device for non-ferromagnetic structures. The surface mounting device also operates under the control of the computer system 36. The computer system may include separate computers mounted on the UAV 2 and the multi-tool module 60a, respectively, and communicatively coupled to each other via electrical cables.

[0058] 8 is a block diagram identifying several components of a motorized hub 62 according to one embodiment, including an inner cylinder 78 rotatable relative to a base 80, and a shroud head 76 carrying a tool translatable relative to the inner cylinder 78. The inner cylinder 78 is rotatably coupled to the base 80 by a bearing 79. The shroud head 76 is translatably coupled to the inner cylinder 78 by a linear slide 77. The hub 62 further includes a lift drive motor 26 and a rotary drive motor 26b. The inner cylinder 78 is operably coupled to the rotary drive motor 26b by a rotary gear train 48. The shroud head 76 is operably coupled to the lift drive motor 26a by a lift mechanism 46. The lift mechanism 46 may include a rack and pinion gear, a lead screw and nut, or other mechanism for lifting the shroud head 76, so that the coupled tool does not contact and thereby scratch the surface of the structure being repaired during rotation of the hub. When the selected tool is vertically aligned with the damaged area to be repaired, the lift drive motor 26a is reversed, causing the lift mechanism 46 to lower the tool into contact with the surface being repaired.

[0059] FIG. 9 is a block diagram identifying several components of a system for holding (temporarily mounting) a multi-tool module in a stable position on a surface of a structure using a vacuum suction system. The vacuum suction system includes a plurality of suction cups 50, a vacuum manifold assembly 52, an electromechanical (e.g., solenoid-actuated) control valve 54 (hereinafter "control valve 54"), and a vacuum pump 56. The vacuum pump 56 is in fluid communication with a first portion of the control valve 54, and the vacuum manifold assembly 52 is in fluid communication with a second portion of the control valve 54. The plurality of suction cups 50 are in fluid communication with the vacuum manifold assembly 52. ​​The term "manifold" is used herein to mean a chamber or duct having several outlets through which fluids can be distributed or collected. These manifolds connect channels in the suction cups 50 to a vacuum system that includes the vacuum pump 56 and the control valve 54. According to an alternative embodiment, each individual suction cup 50 has its own vacuum motor (not shown).

[0060] The computer system 36 (previously described with reference to FIG. 7) is further configured to control the state of a control valve 54 that selectively couples the vacuum pump 56 to the vacuum manifold assembly 52. ​​The vacuum manifold assembly 52 comprises a plurality of vacuum manifolds in fluid communication with the respective suction cups 50. The computer system 36 can be programmed to send a control signal to open the control valve 54. When the valve is open, the computer system 36 also sends a control signal to activate the vacuum pump 56. The vacuum pump 56 applies a vacuum pressure to the vacuum manifold assembly 52, which causes the suction cups 50 to vacuum-suck to the surface of the repairable structure. The vacuum pump 56 is required to maintain a constant vacuum pressure. According to one proposed embodiment, the vacuum pump 56 does not operate continuously. Instead, the vacuum pump 56 continuously monitors the vacuum pressure under the suction cups 50 and activates whenever the vacuum pressure falls below a specified threshold. The system attempts to maintain a pressure differential of about 1 to 2 psi below atmospheric pressure.

[0061] 4 and 4A has the tool attached to the distal end of a cantilever arm fixedly coupled to a shroud head 76 that is translatable along the inner cylinder 78. According to an alternative embodiment, the shroud head 76 may be fixedly coupled to the inner cylinder 78, and a number of rotatable arms may be pivotally coupled to the shroud head 76 to allow the tool to be raised and lowered.

[0062] 10A and 10B are side views of a multi-tool module 60b with rotatable arms 65 according to an alternative embodiment. The module may be a payload carried by a UAV of the type depicted in FIG. 2 or 3A or of a different design. The multi-tool module is shown in two states: with the rotatable arms 65 extended (see FIG. 10A) and with the rotatable arms 65 retracted (see FIG. 10B). In the example depicted in FIG. 10A and 10B, only two rotatable arms 65 are shown, one carrying a removal repair tool 68 and the other carrying an add-on repair tool 70. However, the multi-tool module 60b may have more than two rotatable arms 65.

[0063] The multi-tool module 60b further includes a center ring 81 that is translatable along the inner cylinder 78. The center ring 81 is connected to the rotatable arms 65 by respective links 61. Each link 61 has one end pivotally coupled to a respective lug 63 of the center ring 81 and the other end pivotally coupled to a respective rotatable arm 65. The multi-tool module 60b further includes a lifting mechanism (disposed inside the inner cylinder 78 and not visible in FIGS. 10A and 10B) that, when activated, moves the center ring 81 upward (the movement is indicated by an upward arrow in FIG. 10B). As the center ring 81 rises from its lowest position depicted in FIG. 10A to its higher position depicted in FIG. 10B, a lifting force generated by the lifting mechanism is transferred by the links 61 to the rotatable arms 65. The resulting upward rotation of the rotatable arms 65 lifts the tool away from the surface. While the tool is elevated as seen in Figure 10B, the inner cylinder 78 can be rotated until the selected tool is properly aligned vertically with the damaged area. The tool can then be lowered by translating the center wheel 81 downwards so that it is returned to the lowest position seen in Figure 10A.

[0064] Since all rotatable arms 65 are coupled to the central wheel 81, all arms move in unison when the central wheel 81 moves. According to other embodiments, the rotatable arms 65 can be independently raised and lowered. FIG. 11 is a side view of a multi-tool module 60c having rotatable arms 65 that can be independently retracted (raised) by respective linear actuators 67. According to one proposed embodiment, each linear actuator 67 has a cylinder pivotally coupled to a respective handle 63 of the inner cylinder 78 and a piston rod end pivotally coupled to a respective rotatable arm 65. Each rotatable arm 65 swings upwards when the associated linear actuator 67 is extended.

[0065] According to a further embodiment, the UAV 2 may be provided with a collet module designed to hold only a single tool of a plurality of interchangeable tools instead of holding multiple tools simultaneously. FIG. 12 is a diagram representing a top view of a removal and repair tool 68 (e.g., an abrasive tool) held by the collet module 58 while being carried toward an anomaly 99 on the surface of a structure. Other tools 70, 72, and 74 (previously described) are located at respective tool stations on the ground. The collet module 58 may be a payload 6 carried by the UAV 2 of the type depicted in FIG. 2 or FIG. 3A or of a type having a different design. FIG. 12A is a side view of the collet module 58 engaged with the removal and repair tool 68 depicted in FIG. 12.

[0066] As shown in FIG. 12, the collet module 58 includes a collet mounting plate 98 and a collet 96 for mounting to the payload support frame 8. Each tool has a mounting post 94 that can be gripped or clamped by the collet 96. While the collet 96 is open, the UAV 2 can be flown to a position overlapping and aligned with the mounting post 94 of the tool, and then the UAV 2 is lowered until the open collet 96 surrounds the mounting post 94. The collet 96 is then closed to form a collar around the mounting post 94 and apply a clamping force to hold the tool. The collet 96 opens and closes in response to rotation of the output shaft of a motor (not shown in FIGS. 12 and 12A) in one direction or the other, respectively. The mounting post 94 and collet 96 can have interlocking grooves and protrusions that allow the collet 96 to hold the mounting post 94.

[0067] 13A and 13B are respective portions of a flow chart identifying steps of a method 150 according to one embodiment for inspecting and repairing damaged portions of a structure or object using a UAV 2 with a collet 96 depicted in FIG. 12A. Referring to FIG. 13A, first a first and a second tool are stored at a ground base (step 152). Each of the first and second tools includes a respective mounting post 94. A UAV assigned to perform a repair procedure is flown to a first location, where the collet 96 is aligned with the mounting post 94 of the first tool (step 154). The collet 96 is then closed to clamp the mounting post 94 of the first tool (step 156). The UAV then takes off from the ground base with the first tool as a payload 6 (step 158). The UAV then flies to a repairable structure (step 160) and lands on the surface of the structure (step 162). While the UAV is parked on the surface of the structure, the first tool is used to perform a first repair operation on the area on the surface requiring repair (step 164). Once the first repair operation is completed, the UAV, still carrying the first tool, takes off from the repairable structure (step 166) and then flies back to the first location on the ground base (step 168). While in the first location, the collet 96 is opened to release the mounting post 94 of the first tool (step 170).

[0068] Next, referring to FIG. 13B, after returning the first tool to its storage spot, the UAV flies to a second location, where the collet 96 is aligned with the mounting post 94 of the second tool (step 172). The collet 96 is then closed to clamp the mounting post 94 of the second tool (step 174). The UAV then takes off again from the ground base (step 176), flies to the repairable structure (step 178), and lands on the surface of the structure in the same location as before (step 180). While the UAV is parked on the surface of the structure, it performs a second repair operation using the second tool to the same area where the first repair operation was performed (step 182). Once the second repair operation is completed, the UAV takes off from the repairable structure with the second tool as the payload 6 (step 184), and then flies back to the second location of the ground base (step 186). While in the second position, the collet 96 is opened to release the mounting post 94 of the second tool (step 188). After returning the second tool to its storage spot, the UAV proceeds to its next destination.

[0069] According to some embodiments, the UAV-enabled repair system proposed herein also includes an off-board tracking system for locating the vehicle and the repair tool. The system may be communicatively coupled to the aforementioned control station 40 on the ground. More specifically, the off-board tracking system is configured to provide three-dimensional (3D) localization information for navigation and control of the UAV relative to the target object, and for precisely locating the inspection or repair tool within the frame of reference of the target object and correlating the location data with a 3D model of the target object. Accurate localization tracking for UAV-based repairs may enable the UAV to move the repair module to the correct location and record the 3D coordinate data associated with that location. This 3D information is important for recording the repairs as well as allowing the results of previously performed UAV-enabled inspections to be taken into account. Any one of a variety of techniques may be used to provide the information required to record the 3D location of the activity.

[0070] According to one embodiment, the UAV includes an on-board tracking system that allows the UAV to navigate according to a pre-programmed flight plan. The pre-programmed flight plan followed by the UAV allows the UAV to follow a flight path around a portion of a target object. The system further includes an off-board tracking system having means for wireless communication with the UAV. The off-board tracking system is configured to transmit commands or monitor various operational performance parameters of the UAV, such as remaining fuel and remaining battery power. The off-board tracking system may also be used to generate commands to modify the flight path of the UAV based on the acquired localization data.

[0071] According to one embodiment, 3D localization may be achieved by placing optical targets on the UAV 2 and then using motion capture feedback control to calculate the position of the UAV 2. Closed-loop feedback control using a motion capture system is disclosed in U.S. Pat. No. 7,643,893, the disclosure of which is incorporated herein by reference in its entirety. According to one embodiment, the motion capture system is configured to measure one or more motion characteristics of the UAV 2 during a repair mission. A processor receives the measured motion characteristics from the motion capture system and identifies control signals based on the measured motion characteristics. A position control system receives the control signals and continuously adjusts at least one motion characteristic of the UAV 2 to maintain or obtain a desired motion state. The UAV 2 may be equipped with optical targets in the form of passive retro-reflective markers. The motion capture system, the processor, and the position control system comprise a complete closed-loop feedback control system.

[0072] According to an alternative embodiment, localization tracking of the UAV 2 may be performed using a local positioning system (not shown in the drawings) mounted on or near the target object. The local positioning system may be controlled from the ground and may be used to track the position of the UAV 2 having three or more optical targets. A typical local positioning system comprises a pan-tilt mechanism, a camera mounted on the pan-tilt mechanism, and a laser range meter for emitting a laser beam along a line of sighting vector to the target. The pan-tilt mechanism comprises a pan unit and a tilt unit. The camera comprises a housing in which the laser range meter is mounted. The camera may comprise a still camera (color and / or black and white) for acquiring still images, a video camera for acquiring color and / or black and white video, or an infrared camera for acquiring infrared still images or infrared video of the target. The local positioning system further comprises a computer system configured to measure the coordinates of the optical targets in a local coordinate system of the target object. In particular, the computer system is programmed to control the operation of the pan-tilt mechanism to rotationally adjust the camera to selected angles about the vertical azimuth (pan) axis and the horizontal elevation (tilt) axis. The computer system is also programmed to control the operation of the camera and receive image data from the camera for transmission to the control station 40. The computer system is further programmed to control the operation of the laser range finder and receive range data from the laser range finder for transmission to the control station 40. The local positioning system may further comprise a wireless transceiver and antenna for enabling two-way wireless electromagnetic communication with the control station. The local positioning system preferably has the functionality described in U.S. Patent Nos. 7,859,655, 9,285,296, and 8,447,805, and U.S. Patent Application Publication No. 2018 / 0120196, the disclosures of which are incorporated herein by reference in their entirety. Image data acquired by the video camera of the local positioning system undergoes image processing as disclosed in US Pat. No. 8,744,133.

[0073] An alternative 3D localization approach involves placing two or more visible targets (such as ink marks) placed by the UAV adjacent to the repair area. The marks can be used by the UAV to precisely redirect the UAV to the repair during each successive repair operation. Automated video localization equipment can be employed to redirect the UAV to the repair area using the available marks.

[0074] Although a method for repairing a structure or object using a UAV equipped with a tool has been described with reference to various embodiments, those skilled in the art will recognize that various changes can be made and equivalents substituted for elements thereof without departing from the scope of the teachings herein. Additionally, many modifications can be made to adapt the teachings herein to a particular situation without departing from their scope. It is therefore intended that the claims not be limited to the specific embodiments disclosed herein.

[0075] As used herein, the term "computer system" should be interpreted broadly to include systems having at least one computer or processor, and systems that may have multiple computers or processors communicating over a network or bus. As used in the previous sentence, the terms "computer" and "processor" both refer to a device that has a processing unit (e.g., a central processing unit) and some form of memory (i.e., a computer-readable medium) that stores programs that can be read by the processing unit.

[0076] Additionally, the present disclosure includes embodiments according to the following clauses: Article 1. An apparatus comprising an unmanned aerial vehicle (2) and a multi-tool module (60a, 60b) coupled to the unmanned aerial vehicle, The unmanned aerial vehicle comprises a body frame (4), a plurality of rotor motors (12) attached to the body frame, and a plurality of rotors (10) operably coupled to each of the plurality of rotor motors; The multi-tool module comprises a hub (62) rotatable about an axis of rotation, a plurality of arms (64a-64d, 65) having respective first ends coupled to the hub, a plurality of tools (68, 70, 72, 74) attached to respective second ends of each of the plurality of arms, and a first motor (26a) operably coupled to drive rotation of the hub. Article 2. The multi-tool module further comprises a base (80); 2. The apparatus of claim 1, wherein the hub comprises an inner cylinder (78) rotatable relative to the base. Article 3. 3. The apparatus of claim 2, wherein the hub further comprises a capping head (76) that covers a top of the inner cylinder. Article 4. The cover head is movable in parallel with the top of the inner cylinder, 4. The apparatus according to claim 3, wherein the plurality of arms (64a-64d) are fixedly connected to the covering head. Article 5. 5. The apparatus according to claim 3 or 4, wherein the arms (65) are rotatably connected to the cap head. Article 6. The multi-tool module includes: a wheel (81) translatable along the inner cylinder; and 6. The apparatus of claim 5, further comprising a plurality of links (61), each link having one end rotatably coupled to the wheel and an opposite end rotatably coupled to a respective arm of the plurality of arms. Article 7. 7. The apparatus of claim 5 or 6, wherein the multi-tool module further comprises a plurality of linear actuators (67), each linear actuator having one end rotatably coupled to a respective arm of the plurality of arms. Article 8. The unmanned aerial vehicle further includes a payload support frame (8) pivotably coupled to the body frame; the multi-tool module is attached to the payload support frame; 8. The apparatus of any one of clauses 1 to 7, wherein the payload support frame comprises a plurality of surface mounting devices (16). Article 9. The apparatus of any one of clauses 1 to 8, wherein the plurality of tools includes a subtractive repair tool (68) and an additive repair tool (70). Article 10. An apparatus comprising an unmanned aerial vehicle (2) and a tool pick and place module (22) coupled to the unmanned aerial vehicle, The unmanned aerial vehicle comprises a body frame (4), a plurality of rotor motors (12) attached to the body frame, and a plurality of rotors (10) operably coupled to each of the plurality of rotor motors; the tool pick and place module includes a platform (84) having a plurality of tool stations (88), a tool pick and place robot (82) mounted on the platform, and a plurality of tools (68, 70, 72, 74) disposed at each of the tool stations; The tool pick and place robot comprises a base (80), a hub (62) rotatable about the base, an arm (86) having a first end fixedly coupled to the hub and a second end spaced from the hub, and a tool holder (90) attached to the second end of the arm. Article 11. The hub includes an inner cylinder (78) rotatable relative to the base, and a cap head (76) rotatable in tandem with the inner cylinder and translatable relative to the inner cylinder; 11. The apparatus of claim 10, wherein the first ends of the arms are fixedly coupled to the shroud and extend radially outward from the shroud. Article 12. The tool pick and place robot a first motor (26a) operably coupled to drive rotation of the inner cylinder; and Further comprising a second motor (26b) operably coupled to drive the translational movement of the covering head. Article 13. 13. Apparatus as described in clause 11 or 12, wherein the plurality of tool stations are arranged at respective angularly distributed positions within a circular cylindrical reference frame centered on an axis of rotation of the tool pick and place robot, and the plurality of tools arranged at the plurality of tool stations are arranged at least in part within a length of the arm of the tool pick and place robot. Article 14. The tool holder comprises an electromagnet or an electro-permanent magnet (90); Apparatus as described in clause 13, wherein each of the plurality of tools comprises a permanent magnet arranged on the tool in a position such that when the arm contacts the tool, the respective permanent magnet (92) is magnetically coupled with the electromagnet or electric permanent magnet. Article 15. 15. The apparatus of any one of clauses 10 to 14, wherein the tool holder comprises a vacuum gripper. Article 16. 16. The apparatus of any one of clauses 10 to 15, wherein the plurality of tools includes a subtractive repair tool (68) and an additive repair tool (70). Article 17. An apparatus comprising an unmanned aerial vehicle (2) and a collet module (58) coupled to the unmanned aerial vehicle, The unmanned aerial vehicle comprises a body frame (4), a plurality of rotor motors (12) attached to the body frame, and a plurality of rotors (10) operably coupled to each of the plurality of rotor motors; The collet module includes a collet (96) configured to transition between a clamping state and a non-clamping state. Article 18. The apparatus described in clause 17, further comprising a tool having a mounting post (94) that is clamped by the collet in a clamping state, the tool being selected from a group of tools including a subtractive repair tool (68), an add-on repair tool (70), a cleaning tool (74), and a drying tool (72). Article 19. A method for repairing a structure using an unmanned aerial vehicle (2) equipped with a collet module (58), comprising: storing a first tool (68, 70, 72, 74) and a second tool (68, 70, 72, 74), each having a respective mounting post (94), on a ground station (40); flying the unmanned aerial vehicle to a first position where a collet (96) of the collet module is aligned with the mounting post of the first tool; closing the collet to clamp the mounting post of the first tool; flying the unmanned aerial vehicle toward a structure to be repaired using the first tool slaved to the unmanned aerial vehicle; Landing the unmanned aerial vehicle on a surface (9) of the structure; The method includes performing a first repair operation on an area on the surface of the structure using the first tool while the unmanned aerial vehicle is parked on the surface of the structure. Article 20. 22. The method of claim 19 or 21, further comprising determining a position of the first tool within a reference frame of the structure using an off-board tracking system. Article 21. flying the unmanned aerial vehicle to the first location; opening the collet to release the mounting post of the first tool; flying the unmanned aerial vehicle to a second location where the collet is aligned with the mounting post of the second tool; closing the collet to clamp the mounting post of the second tool; flying the unmanned aerial vehicle, the unmanned aerial vehicle having the second tool slaved to the unmanned aerial vehicle, toward the structure; landing the unmanned aerial vehicle on the surface of the structure; and The method of claim 19, further comprising performing a second repair operation on the area on the surface of the structure using the second tool while the unmanned aerial vehicle is parked on the surface of the structure. Article 22. 22. The method of claim 21, wherein the unmanned aerial vehicle is operable to move using a predetermined flight path that is updated using position and orientation data obtained from an off-board tracking system.

Claims

1. An apparatus comprising an unmanned aerial vehicle (2) and a multi-tool module (60a, 60b) coupled to the unmanned aerial vehicle, The unmanned aerial vehicle comprises a body frame (4), a plurality of rotor motors (12) attached to the body frame, and a plurality of rotors (10) operably coupled to each of the plurality of rotor motors; the multi-tool module comprises a base (80), a hub (62) rotatable relative to the base about an axis of rotation, a plurality of arms (64a-64d, 65) having respective first ends coupled to the hub, a plurality of tools (68, 70, 72, 74) attached to respective second ends of each of the plurality of arms, and a first motor (26a) operably coupled to drive rotation of the hub; The hub includes an inner cylinder (78) rotatable relative to the base, and a capping head (76) that covers the top of the inner cylinder; The cover head is vertically translatable along the inner cylinder relative to the top of the inner cylinder, The plurality of arms (64a-64d) are fixedly connected to the cap head.

2. The device of claim 1 , wherein the plurality of arms (65) are rotatably coupled to the cap head.

3. The multi-tool module includes: A wheel (81) vertically translatable along the inner cylinder; and 3. The apparatus of claim 2, further comprising a plurality of links (61), each link having one end rotatably coupled to the wheel and an opposite end rotatably coupled to a respective one of the plurality of arms.

4. 4. The apparatus of claim 2 or 3, wherein the multi-tool module further comprises a plurality of linear actuators (67), each having one end rotatably coupled to a respective arm of the plurality of arms.

5. The unmanned aerial vehicle further includes a payload support frame (8) pivotably coupled to the body frame; the multi-tool module is attached to the payload support frame; The apparatus of any one of claims 1 to 4, wherein the payload support frame comprises a plurality of surface mounting devices (16).

6. An apparatus comprising: an unmanned aerial vehicle (2) and a tool pick and place module (22) coupled to the unmanned aerial vehicle, The unmanned aerial vehicle comprises a body frame (4), a plurality of rotor motors (12) attached to the body frame, and a plurality of rotors (10) operably coupled to each of the plurality of rotor motors; the tool pick and place module comprises a platform (84) having a plurality of tool stations (88), a tool pick and place robot (82) mounted on the platform, and a plurality of tools (68, 70, 72, 74) disposed at the respective tool stations; The tool pick and place robot comprises a base (80), a hub (62) rotatable about the base, an arm (86) having a first end fixedly coupled to the hub and a second end spaced from the hub, and a tool holder (90) attached to the second end of the arm; The hub includes an inner cylinder (78) rotatable relative to the base, and a cap head (76) rotatable in tandem with the inner cylinder and translatable vertically along the inner cylinder relative to a top of the inner cylinder; The first ends of the arms are fixedly coupled to the shroud and extend radially outwardly from the shroud.

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