A drone for inspecting a building or structure

Abstract

A drone (100) for inspecting a building or structure, the drone comprising: a body (101) having a propulsion system (105a, 105b) for manoeuvring the device relative to the building or structure; and a sensor (103) for capturing sets of inspection data from regions of the building or structure, each set of inspection data being descriptive of a condition of a respective region, the sensor defining a pitch axis and a yaw axis; the sensor being at least partially rotatable about one or more of the pitch axis and yaw axis with respect to the body (101).

Description

[0001] A drone for inspecting a building or structure

[0002] FIELD

[0003] Embodiments described herein relate to a drone for inspecting a building or structure.

[0004] BACKGROUND

[0005] In many industries, it is necessary to inspect buildings and other structures for any flaws that could undermine their structural integrity. Examples of this include both the nuclear industry and the oil and gas industry, where containers and other assets are used to store large quantities of hazardous and / or volatile substances. Other examples include the mining industry, where there is a clear need to monitor for instability in the walls or ceiling of mineshafts, as well as in the transport sector and maritime industry; observing the structural integrity of a ship’s hull, for example, is critical for maintaining the vessel and keeping it in a seaworthy condition.

[0006] In many cases, inspection of such structures is carried out manually by assembling scaffolding rigs that maintenance personnel can then climb in order to inspect the walls, ceilings and / or other surfaces of the structure. However, this approach is both costly and time consuming, and exposes the human operators to risk of injury. To address this problem, one possibility is to use an unmanned aerial vehicle or drone to inspect the structure. The drone is provided with a camera or other sensor device that can be used to capture data from the structure during flight, with the maintenance personnel remaining at a safe location as it does so. Depending on the shape of the building or structure, however, it may sometimes be difficult to manoeuvre the drone into a position where its sensor is able to successfully capture the data.

[0007] It is desirable, therefore, to provide a drone that is capable of successfully capturing sensor data from different shaped buildings and structures.

[0008] SUMMARY

[0009] According to a first aspect of the present invention, there is provided a drone for inspecting a building or structure, the drone comprising: a body having a propulsion system for manoeuvring the device relative to the building or structure; and a sensor for capturing sets of inspection data from regions of the building or structure, each set of inspection data being descriptive of a condition of a respective region, the sensor defining a pitch axis and a yaw axis; the sensor being at least partially rotatable about one or more of the pitch axis and yaw axis with respect to the body.

[0010] The sensor may be least partially rotatable about both of the pitch axis and yaw axis with respect to the body.

[0011] The sensor may be held in a sensor mount. The sensor may be rotatable about the one or more of the pitch axis and yaw axis of the sensor by rotating the sensor mount.

[0012] The sensor may be spring-loaded in the sensor mount.

[0013] The sensor mount may comprise a first part that is rotatably coupled to the body, such that the first part of the sensor mount is rotatable about one or other of the pitch or yaw axis of the sensor with respect to the body.

[0014] The sensor mount may comprise a second part that is rotatably coupled to the first part, such that the second part of the sensor mount is rotatable about the other one of the pitch and yaw axis of the sensor with respect to the body.

[0015] The sensor mount may comprise one or more magnets for coupling the sensor to a surface of the building or structure under inspection.

[0016] The sensor mount may have a first face arranged to contact the surface under inspection, the magnets being arranged so as to couple of the first face to the surface.

[0017] A head of the sensor may be arranged within a central region of the first face, the magnets being arranged circumferentially around the head of the sensor.

[0018] The drone may comprise one or more motors for rotating the sensor about the pitch and / or yaw axis with respect to the body. The one or more motors may be configured to apply a torque to the sensor mount. The applied torque may be large enough to overcome the magnetic coupling between the first face of the sensor mount and the surface under inspection and cause the first face to decouple from the surface. In the absence of the motor being activated, the sensor mount may be free to rotate about the pitch and / or yaw axis through a first range of degrees. The sensor mount may be caused to rotate through a larger range of degrees by activation of the motor.

[0019] The sensor may comprise an acoustic transducer.

[0020] The drone may comprise a reservoir for storing a supply of coupling medium during flight of the drone.

[0021] The reservoir may be reversibly detachable from the body of the drone.

[0022] The drone may comprise a delivery system for delivering a portion of the coupling medium from the reservoir to the interface between the head of the acoustic transducer and the surface of the building or region under inspection.

[0023] The delivery system may comprise a pump operable to pump the coupling medium from the reservoir through a tube to the interface between the head of the acoustic transducer and the surface under inspection.

[0024] The body of the drone may have a standard flight orientation in which the body is substantially horizontal with respect to the ground. The sensor may be at least partially rotatable about one or more of the pitch axis and yaw axis whilst the body remains in the standard flight orientation.

[0025] The sensor may be positioned on an arm that extends from the body. The arm may be reversibly connectable to the body at one or more locations on the body and / or in one or more orientations.

[0026] The drone may comprise a LIDAR scanner, wherein the arm is arranged such that light from the LIDAR scanner is able to pass uninterrupted between the body and the arm.

[0027] The drone may comprise one or more cleaning apparatuses for wiping a surface of the building or structure under inspection prior to capturing each set of inspection data.

[0028] The drone may comprise a light source arranged to project a spot of light on a region of the building or structure with which the sensor is aligned. BRIEF DESCRIPTION OF DRAWINGS

[0029] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

[0030] Figure 1 shows an inspection device according to an embodiment;

[0031] Figure 2A shows a schematic of a conventional inspection device with an inspection sensor being used to obtain sensor measurements from a vertical surface;

[0032] Figure 2B shows how the conventional inspection device of Figure 2A may fail to obtain a tight seal between the inspection sensor and the surface if the surface has a sloped profile;

[0033] Figure 2C shows how the conventional inspection device of Figure 2B may obtain a tight seal between the inspection sensor and the sloped surface by titling the entire body of the inspection device relative to the surface;

[0034] Figure 3 shows a sensor portion of an inspection device according to an embodiment;

[0035] Figure 4A shows how the conventional inspection device of Figure 2A may fail to obtain a tight seal between the inspection sensor and the surface if the surface has a sloped profile;

[0036] Figure 4B shows schematically how an inspection device with an inspection sensor according to an embodiment may obtain a tight seal between the inspection sensor and a sloped surface by rotating the inspection sensor about one or both of the pitch axis and yaw axis of the sensor, relative to a body of the inspection device;

[0037] Figure 5A shows an end-on view of the sensor portion of Figure 4;

[0038] Figure 5B shows a cross section taken through the sensor portion shown in Figure 5A;

[0039] Figure 6 shows another view of the sensor portion shown in Figures 3 and 5;

[0040] Figure 7A shows a cross-section through the line A - A’ of Figure 6; Figure 7B shows a cross section through the line B - B’ of Figure 6;

[0041] Figure 7C shows a cross section through the line C - C’ of Figure 6;

[0042] Figure 8A shows a view of the sensor portion as shown in Figure 7C, with a first part of the sensor holder removed;

[0043] Figure 8B shows a view of the sensor portion as shown in Figure 8A, with the first part of the sensor holder in place;

[0044] Figure 9A shows a view of the sensor portion of Figure 8B, with the first part of the sensor holder rotated to a first position;

[0045] Figure 9B shows a view of the sensor portion of Figure 8B, with the first part of the sensor holder rotated to a second position;

[0046] Figure 9C shows a view of the sensor portion of Figure 8B, with the first part of the sensor holder rotated to a third position;

[0047] Figure 10A shows a view of the sensor portion as shown in Figure 8A, with the arm connected to the motor axle having been rotated to a first position;

[0048] Figure 10B shows a view of the sensor portion as shown in Figure 10A, with the first part of the sensor holder in place;

[0049] Figure 10C shows a view of the sensor portion as shown in Figure 8A, with the arm connected to the motor axle having been rotated to a second position;

[0050] Figure 10D shows a view of the sensor portion as shown in Figure 10C, with the first part of the sensor holder in place;

[0051] Figure 11 A shows an end-on view of the sensor portion of Figure 3;

[0052] Figure 11 B shows an end-on view of the sensor portion of Figure 3, with the sensor holder having been rotated 90 degrees about the pitch axis of the sensor;

[0053] Figure 12 shows an inspection device according to an embodiment; Figure 13 shows a plan view of an inspection sensor in an inspection device according to an embodiment;

[0054] Figure 14A shows the second part of the sensor holder of Figure 13;

[0055] Figure 14B shows the second part of the sensor holder of Figure 13 with the sensor mounted in the sensor holder;

[0056] Figure 15A shows the sensor holder of Figure 13 having been rotated anti-clockwise about the yaw axis relative to the body of the inspection device;

[0057] Figure 15B shows the sensor holder of Figure 13 having been rotated clockwise about the yaw axis relative to the body of the inspection device.

[0058] Figure 16A shows an example sensor mount in which the sensor is spring-loaded within the sensor mount, according to an embodiment;

[0059] Figure 16B shows the sensor mount of Figure 16A with the sensor pressed back in the barrel of the sensor mount;

[0060] Figure 16C shows the sensor mount of Figure 16A with the sensor pressed still further back in the barrel of the sensor mount;

[0061] Figure 16D shows the spring-loaded mechanism used in mounting the sensor in the sensor mount of Figures 16A - C;

[0062] Figure 17A shows a side-on view of the sensor portion in an embodiment in which the sensor portion includes a light source for illuminating a spot on a surface with which the sensor head is currently aligned;

[0063] Figure 17B shows another view of the sensor portion of Figure 17A;

[0064] Figures 18A - 18C show examples of how the light source of Figures 17A and 17B may be mounted on a first part of the sensor holder in an embodiment;

[0065] Figure 19 shows how the light source of Figures 17A and 17B may be mounted on a first part of the sensor holder in an embodiment;

[0066] Figure 20A shows an inspection device according to an embodiment;

[0067] Figure 20B shows an inspection device according to an embodiment;

[0068] Figure 20C shows an inspection device according to an embodiment;

[0069] Figure 21A shows an inspection device according to an embodiment;

[0070] Figure 21 B shows an inspection device according to an embodiment;

[0071] Figure 21 C shows an inspection device according to an embodiment;

[0072] Figure 22A shows an example of how the arm of the inspection device may be attached to the body of the inspection device according to an embodiment;

[0073] Figure 22B shows a further example of how the arm of the inspection device may be attached to the body of the inspection device according to an embodiment;

[0074] Figure 23 shows an arm on which the sensor portion of an inspection device is mounted, according to an embodiment;

[0075] Figure 24A shows an example in which a reservoir for holding a coupling medium is contained within the arm of Figure 23; and

[0076] Figure 24B shows an example of how the reservoir of Figure 24A may be removed and replenished.

[0077] DETAILED DESCRIPTION

[0078] Figure 1 shows an example of an inspection device 100 according to an embodiment. The inspection device comprises a drone or unmanned aerial vehicle (UAV) that can be used to inspect the walls, ceiling and / or other surfaces of a building or structure.

[0079] The inspection device 100 comprises a body 101 and a sensor portion 103.

[0080] The body 101 includes a propulsion system that is used to maneuver the device relative to the structure. The propulsion system itself comprises one or more propulsion members 105a, 105b that are used to generate lift along the vertical axis, and which may further be used to translate the inspection device horizontally in space. In the present embodiment, the propulsion system is based on that of a conventional quadcopter, with each propulsion member 105a, 105b comprising a motorised propeller that is housed within or mounted on the body 101. The propulsion members are arranged in a substantially horizontal plane. During flight, the inspection device will adopt a standard flight configuration in which the plane of the propulsion members remains substantially horizontal to the ground. The propulsion system may facilitate motion of the device along each axis independently; thus, the propulsion system may provide for movement in any direction that an operator of the device selects.

[0081] Before commencing inspection, the inspection device may be programmed with a predetermined flight trajectory, which will then be implemented using the propulsion system. In other embodiments, the device may determine its own flight path autonomously as the inspection progresses, or else the flight path may be controlled manually by an operator via a control pad (not shown in Figure 1).

[0082] In the present embodiment, the body includes a depth sensor 107 that is mounted above the propulsion system. The depth sensor 107 may comprise one of a number of different types of sensor for capturing spatial information in three dimensions. In some embodiments, the depth sensor 107 comprises a LIDAR unit, which by scanning one or more light beams in different directions and monitoring properties of the beams reflected back towards the device from different surfaces can build up a 3D image or point cloud of the device’s surroundings. In other cases, the depth sensor 107 may comprise a structured light scanner that captures images of the surfaces when illuminated with a particular light pattern; depth information can then be recovered by observing the change in intensity seen at different points when a phase shift is introduced in the illumination pattern. The depth sensor 107 may comprise, for example, a time of flight camera, a holographic scanner, or a stereo camera. Other types of depth sensor capable of 3D imaging may also be used. For example, the depth sensor 107 may be configured to capture 3D data using laser triangulation.

[0083] The depth sensor 107 may be provided as a single component or as several individual components, with the data from each individual component then being combined to generate a 3D image or point cloud of the device’s surroundings. For example, the depth sensor 107 may comprise several cameras, arranged at different positions on the device 100, so as to capture images of the same region from different angles with the images then being combined to produce a single set of depth data for that region.

[0084] The inspection device 100 includes a controller unit 108 that houses one or more computer processors and electronics used to control the propulsion system and the different sensors on-board the device. The controller unit may also include a SLAM (Simultaneous Localization and Mapping) module that can be used to analyse the data captured by the depth sensor 107 to map the surrounding environment of the inspection device. The SLAM module may be used to determine the position of the inspection device as it maneuvers relative to the structure, as described in further detail in W02022 / 008271A1, the contents of which are incorporated herein by reference. By doing so, it is then possible to tag each set of inspection data with positional data indicating the position of the device 100 at the time the inspection data was captured. The positional data associated with each set of inspection data can enable the operator I maintenance personnel to determine which part of the structure each set of inspection data relates to, and in turn to identify the precise location of any faults seen within a particular set of inspection data.

[0085] The sensor portion 103 of the device includes an inspection sensor 109 that is used to inspect the surfaces of the structure. As the device maneuvers relative to the structure, the inspection sensor 109 is used to collect respective sets of inspection data from different regions of the structure. The sets of inspection data can then be used to identify any cracks or other faults that signal a degradation in the structure, and / or which might threaten its structural integrity.

[0086] In the present embodiment, the inspection sensor 109 is one that is suitable for NonDestructive Testing (NDT). Non-Destructive Testing encompasses a wide range of techniques in which the properties of a material or component of a structure can be assessed without causing damage to the part under evaluation. By way of example, the sensor may be configured to perform one or more of Ultrasonic Testing, Electromagnetic Testing and Magnetic Flux Leakage Detection. In the case of Ultrasonic Testing, the sensor 109 comprises an acoustic transducer for generating acoustic waves and detecting the acoustic signals reflected from different layers of the structure. The detected acoustic signals can then be used to build up a picture of the structure. In the case of Electromagnetic Testing, the inspection device 100 comprises a probe for inducing an electric current in an electrically conductive part of the structure. The inspection sensor 109 may then be used to sense the resultant electromagnetic fields close to the surface, with any faults or defects in the structure being visualized as a disturbance in those electromagnetic fields. In other embodiments, the sensor may use measurements of Magnetic Flux Leakage to inspect structures made of steel or other materials having magnetic properties. The inspection device may comprise a magnet for creating a magnetic field that will saturate the steel contained within the structure and the inspection sensor 109 may then be configured to sense changes in magnetic flux density that may be indicative of degradation of the steel structure.

[0087] The sensor 109 is mounted on an arm 111 that is connected to the body 101 and extends horizontally, parallel to the plane of the propulsion members 105a, 105b. In other embodiments, the arm may be mounted so as to extend upwards or downwards. The arm 111 may extend slightly beyond the end of the body 101 , allowing the sensor 109 to make contact with the building or structure under inspection whilst keeping a short distance between the body 101 and structure. In the present embodiment, the arm 111 extends above the depth sensor 107, such that light emitted by the depth sensor 107 is able to travel between the body 101 and the sensor arm 111 without interruption.

[0088] Where the inspection sensor 109 comprises an ultrasonic transducer, it is important to ensure that the transducer is in close proximity to the surface, without any pockets of air separating the two. To help achieve this, a coupling medium such as an ultrasound gel may be used to form a bridge between the transducer and the surface during the time in which measurements are being carried out, minimising any back-reflections of the ultrasonic waves as they pass from the transducer to the surface. In the present embodiment, the coupling medium is contained within a syringe 113 that is mounted towards the rear of the sensor arm 111. The barrel of the syringe serves as a reservoir for the gel during the inspection. The hub of the syringe 113 is connected to a flexible tube whose other end is open and arranged above the face of the transducer. A pump housed within the body 101 is operable by the controller unit 108 to propel a portion of the ultrasonic gel contained in the barrel along the tube towards the transducer. Upon leaving the tube, the gel is caused to trickle down over the face of the transducer under the force of gravity. The pump may be activated by the controller unit 108 in synchronisation with the transducer, such that the front face of the transducer remains coated in the ultrasonic gel as the inspection device approaches the surface and begins collecting the inspection data. In some embodiments, rather than using an ultrasonic gel, an alternative coupling medium may be used such as a membrane or other filament that does not require continuous re-application. The membrane or filament may be somewhat soft so as to absorb any unevenness in the surface to which the sensor is being coupled. The inspection device may also have a cleaning apparatus such as a brush or air blower for clearing any surface debris from the surface prior to capturing each set of inspection data.

[0089] In cases where the surface under inspection extends perpendicularly to the body of the inspection device, it is possible to form a tight seal between the sensor and the surface by manoeuvring the body of the inspection device towards the surface and bringing the sensor into contact with that surface, with the coupling medium filling any slight air pocket between them. This can be seen in Figure 2A, where the sensor 109 is manoeuvred such that it is flush with the surface 200. However, where the surface 200 has a sloped profile, a problem arises in maintaining the necessary contact between the sensor 109 and the surface 200; this is the situation shown in Figure 2B, in which the slope of the surface leads to an unbridgeable gap 203 between the sensor 109 and the surface 200. The sensor may achieve the necessary contact with the surface 200 by rotating the entire body of the inspection device as shown in Figure 2C. However, not only does this place an additional control burden on the personnel operating the inspection device, but it requires that the inspection device depart from its more stable configuration in which the body is aligned horizontally with the ground, with the propulsion members facing directly downwards.

[0090] Embodiments described herein serve can alleviate the above problem by allowing the sensor 109 greater freedom of movement relative to the body of the inspection device. This can be further understood with reference to Figures 3 to 15.

[0091] Figure 3 shows the sensor portion 103 in more detail. The sensor comprises an ultrasonic transducer 301 that is held in a sensor holder, the sensor holder being formed of a first part 303 and a second part 305. The second part 305 has an end face 305a arranged to press against the surface of a structure being inspected. The head 307 of the transducer 301 is received in an aperture of the end face 305, such that the head 305 of the transducer is substantially flush with that face. Accordingly, with the end face 305a of the sensor holder pressed against the surface under inspection, the transducer head 307 will press against that same surface. As shown in Figure 4, with the sensor 301 mounted in the sensor holder, the sensor can be seen to define three axes: a roll axis, yaw axis and pitch axis. The roll axis lies along the direction in which the transducer head 307 is facing, with the pitch and yaw axes being orthogonal to the roll axis. As discussed in further detail below, the first part 303 of the sensor holder is rotatably coupled to a head portion 309 of the arm 111 , allowing the sensor holder to rotate about the pitch axis of the sensor relative to the arm 111 and body of the inspection device. The second part 305 of the sensor holder is in turn rotatably coupled to the first part 303 of the sensor holder, allowing the second part 305 of the sensor holder to rotate about the yaw axis of the sensor 301 relative to the arm 111 and body of the inspection device. The head portion 309 houses one or more servo-motors 311 that may be used to drive the rotation of the sensor holder about the pitch and / or yaw axis of the sensor 301 relative to the body of the inspection device. Control signals for controlling the rotation of the first 303 and / or second 305 parts of the sensor holder are sent to the servo motor(s) from the on-board controller unit 108.

[0092] Figures 4A and 4B show schematically how by allowing the sensor holder to rotate about its pitch axis relative to the body 101, a tight seal can be obtained between the sensor 109 and the surface 200 under inspection. In more detail, Figure 4A shows the same scenario as in Figure 2A, in which the sloped profile of the surface 200 results in a gap 203 being formed between the sensor 109 and the surface; Figure 4B in turn shows how the rotation of the sensor holder about the pitch axis allows the sensor 109 to remain flush with the surface 200, while the body 101 of the inspection device remains in its stable horizontal flight configuration.

[0093] Figure 5A shows an end-on view of the head portion 309 and sensor holder. In the present embodiment, the end face 305a of the sensor holder has a wheel-like configuration, with a central portion 501 and a rim 503 that are connected to one another by a series of spokes 505a, 505b, 505c, 505d. The head 307 of the transducer is received within the central portion 501 of the end face.

[0094] In the present embodiment, the end face 305a of the sensor holder comprises one or more magnets for coupling the sensor holder to the wall or surface under inspection. Figure 5B shows a cross-section through the end-face of the sensor holder; here, the spokes 505a, 505b, 505c, 505d can each be seen to house a magnet 507a, 507b, 507c, 507d. Thus, in the present embodiment, the magnets are arranged circumferentially around the head 307 of the transducer. The magnets 507a, 507b, 507c, 507d may be permanent magnets or electromagnets. In the event that the structure being inspected is magnetic (e.g. made of steel), the magnet(s) 507a, 507b, 507c, 507d serve to couple the end face 305a to the surface, thereby holding the head 307 of the transducer firmly in position whilst ultrasound readings are taken.

[0095] Figure 6 shows a further view of the sensor portion 103 and the head portion 309, with reference lines A - A’, B - B’ and C - C’ marked in dashed lines. Figures 7A, 7B and 7C show vertical cross sections of the inspection portion taken along the respective lines A - A’, B - B’ and C - C’ of Figure 6, as viewed along the direction indicated by the arrow 601.

[0096] Figure 7A shows the second part 305 of the sensor holder coupled to an upper surface of the first part 303 of the sensor holder. The transducer cable 301 can be seen to extend parallel to the sensor arm 111 along the roll axis of the sensor and is received in the second part 305 of the sensor holder. The underside of the head portion 309 is visible beneath the sensor holder.

[0097] Figure 7B shows more clearly how the head 307 of the transducer is received within the central portion 501 of the end face 305a of the second part 305 of the sensor holder.

[0098] Figure 7C shows more clearly the first part 303 of the sensor holder mounted on the head portion 309. The first part 303 of the sensor holder is a substantially planar member that is coupled to the head portion 309 such that it is able to rotate in the vertical plane (i.e. to rotate about the pitch axis of the sensor).

[0099] The rotation of the first part 303 of the sensor holder can be further understood with reference to Figures 8 to 11. Figure 8A shows the same view of the sensor portion as Figure 7C, but with the first part 303 of the sensor holder removed to reveal the head portion 309 in full. As shown in Figure 8A, the head portion 309 includes an arm 801 that is connected at one end to the axle of the servo-motor 311 housed in the head portion 309. A nut 803 is used to secure the arm to the motor axle. At the other end of the arm 801 is a second nut 805 that is received within a groove 807 in the head portion 309.

[0100] Figure 8B shows the same view as in Figure 7C, with the first part 303 of the sensor holder back in place. As shown in Figure 8B, the first part 303 of the sensor holder has two apertures, the first of which is positioned over the axle of the motor. In assembling the sensor holder, the nut 803 is removed so as to enable the first part 303 of the sensor holder to be placed over the motor axle; the nut 803 is then replaced, thereby securing the first part 303 of the sensor holder in position. The second aperture of the first part 303 of the sensor holder is aligned with the second end of the arm 801. As with the first nut 803, the second nut 805 is removed and then re-attached once the first part 303 of the sensor holder is in position.

[0101] The second aperture is elongated to form a small channel 809 in the first part 303 of the sensor holder. By virtue of this channel 809, the first part 303 of the sensor holder is free to rotate through a certain small number of degrees without activation of the motor, the precise number of degrees being determined by the length of the channel 809. This is further understood with reference to Figures 9A, 9B and 9C, which show the first part 303 of the sensor holder rotated to three different positions, with the arm 801 remaining stationary in the same position as in Figure 8A. In Figure 9A, the first part 303 of the sensor holder is rotated upwards about the pitch axis of the sensor, with its rotation being constrained at the point at which the nut 805 contacts the upper end of the channel 809. Figure 9B shows the first part 303 of the sensor holder in the same position as in Figure 8B, with the second nut 805 now located midway along the channel 809. Figure 9C shows the first part 303 of the sensor holder rotated downwards about the pitch axis, with its rotation constrained at the point at which the nut 805 contacts the lower end of the channel 809.

[0102] The freedom to rotate through a small range of degrees may allow the inspection sensor to remain coupled to a wall or surface under inspection even as the body of the device undergoes small vibrations and shifts in position caused by wind I small variations in air density etc. Such shifts or vibrations might otherwise wrench the head of the sensor away from the surface in the event the sensor holder were held rigidly fixed to the body of the device.

[0103] The first part 303 of the sensor holder can be rotated through a larger number of degrees by engaging the servo motor. As the motor is engaged, the arm 801 is caused to rotate about the axis of the motor, with the second nut 805 travelling along the groove 807. Figures 10A and 10B show views of the sensor portion with and without the first part 303 of the sensor holder, with the arm 801 having rotated to the point where the second nut 805 is now located at the bottom end of the channel 809. At this point, the contact between the nut 805 and the edge of the channel 809 will cause the arm to engage with the first part 303 of the sensor holder, forcing the first part 303 of the sensor holder to rotate about the axle of the motor as the nut 805 moves downwards along the groove 807. Figure 10C shows the position of the arm 801 at a later point in time when the arm has completed a 90 degree rotation from its starting position. Figure 10D shows the same view as in Figure 10C with the first part 303 of the sensor holder in place. Here, the first part 303 of the sensor holder is oriented vertically as a result of its being caused to rotate by the movement of the nut 805 along the groove 807.

[0104] By rotating the sensor holder as shown in Figure 10D, it is possible to obtain sensor measurements from a surface oriented parallel to the ground, such as a roof or ceiling, whilst the body 101 of the inspection device remains in its standard horizontal flight configuration. As an example, Figures 11 A and 11 B show end-on views of the sensor portion, with the sensor holder being held at different rotational orientations. Figure 11 A shows the case in which the end face 305a of the sensor holder faces along the horizontal axis of the inspection device. Figure 11 B shows the case in which the first part 303 of the sensor holder is rotated 90 degree about the pitch axis by the action of the motor; here, the end face 405a faces upwards from the body of the inspection device. Figure 12 shows an example of the inspection sensor 103 being used to obtain sensor measurements from a steel tile 1201 oriented horizontally. The magnets that surround the transducer head in the end face of the sensor holder provide a tight coupling with the steel surface, ensuring that the transducer head remains in position as measurements are taken.

[0105] It will be appreciated that in addition to orienting the sensor to couple to different surfaces, the motor may serve a further purpose by helping to uncouple the sensor from the surface under inspection once measurements are complete. In conventional inspection devices, once the inspection sensor is coupled to the surface - and particularly where magnetic coupling is used - it can be difficult to disengage the inspection sensor from a surface without the inspection device experiencing a jolt in position; this can be problematic if operating in confined spaces, for example, where such a jolt may cause the device to collide with neighbouring walls. In contrast, in embodiments described herein, once the magnets contained within the sensor holder have coupled to a surface under inspection, the motor may be used to apply a torque to the sensor holder. The torque will eventually become large enough to overcome the magnetic coupling between the sensor holder and the surface under inspection, effectively peeling the sensor holder away from the surface without the body of the inspection device undergoing any significant shift in position. In this way, embodiments not only provide a means to tightly couple the inspection sensor to surfaces having differing slants and orientations, but can further enable the inspection sensor to easily disengage from those surfaces once measurement is complete and without causing any unnecessary motion in the body of the device as a whole.

[0106] In addition to rotating about the pitch axis, the inspection sensor 109 may rotate about the yaw axis. This can be understood with reference to Figures 13 to 15. Figure 13 shows a view of the inspection sensor as seen from directly above. Here, the second part 305 of the sensor holder is seen to be rotatably coupled to the first part of the sensor holder by a pivot member 1301 , allowing the second part 305 of the sensor holder to rotate about the yaw axis of the sensor. The rotation of the second part 305 of the sensor holder is constrained by a nut 1303 that projects upwards from the first part 303 of the sensor holder and is received in a guide aperture 1305 formed towards the rear of the second part 305 of the sensor holder. Figure 14A shows the second part 305 of the sensor holder in isolation as seen from above, whilst Figure 14B shows the second part 305 of the sensor holder with the transducer received inside the holder.

[0107] Figure 15A shows the second part 305 of the sensor holder having been rotated clockwise about the pivot member 1301. At this point, the second part 305 of the sensor holder is close to the limit of its rotational motion in the clockwise direction, with the pin 1303 approaching the end of the guide aperture 1305. Figure 15B shows the second part 305 of the sensor holder rotated anti-clockwise about the pivot member 1301. Here, the second part 305 of the sensor holder is shown to be close to the limit of its rotational motion in the anti-clockwise direction, with the pin 1303 now approaching the opposite end of the guide aperture 1305.

[0108] As in the case of the channel 809 shown in Figures 8 to 10, it will be appreciated that the guide aperture 1305 may be designed to facilitate a greater or lesser degree of rotational freedom by varying the length of the guide aperture. In doing so, the second part 305 of the sensor portion may be allowed to rotate through a greater or smaller angle before the pin 1303 reaches the end of the guide aperture 1305.

[0109] It will be seen from the above, therefore, that in embodiments described herein, the inspection sensor may have ten degrees of freedom; that is, in addition to translating the inspection device in three dimensions, it will be possible to rotate the inspection sensor clockwise and anti-clockwise about both the pitch axis and the yaw axis of the sensor, relative to the body of the inspection device. The ability to rotate the inspection sensor in this way can enable the inspection sensor to couple successfully to buildings or structures whose surfaces have a range of different gradients, whilst avoiding the need to tilt the entire body of the device.

[0110] The embodiments described above capture sensor measurements using a standard piezoelectric ultrasound transducer that is used to generate sound waves that pass into the surface under inspection. However, it will be appreciated that other types of transducer may be used, including an Electro Magnetic Acoustic Transducer (EMAT). Unlike in the case of the piezoelectric transducer, the EMAT induces ultrasonic waves in the surface by using one or more magnets and electrical coils to generate a Lorentz force within the surface, in turn producing an elastic wave that propagates through the surface. Any ensuing reflections can then be detected by currents induced inside the receiving coil of the EMAT. Thus, in embodiments where an EMAT is used, it will not be necessary to include the coupling gel, as the sound waves will be generated within the surface itself, rather than having to pass through the gap between the inspection sensor and the surface.

[0111] Further adaptions of the embodiments described herein are also possible. Figure 16A shows an example embodiment in which the sensor is spring-loaded, such that the transducer head 307 will project outwards from the end face 305a of the second part 305 of the sensor holder. Figure 16B shows how the transducer head 307 may be pressed back inside the barrel of the second part 305 of the sensor holder as the end face 305a is pressed against a surface; in doing so, the transducer head 307 will be flush with the end face 305a. Figure 16C shows how the transducer head 307 may be pushed still further back inside the barrel of the second part 305 of the sensor holder, whilst Figure 16D shows the spring(s) 1601 used to bias the transducer head forwards such that the transducer head will project from the end face 305a of the second part 305 of the sensor holder. By spring-loading the transducer head 307 in this manner, it is possible to ensure that the transducer head 307 will always remain flush with any surface that the end-face is pressed against, in turn ensuring a tight seal between the transducer head 307 and that surface.

[0112] Figure 17A shows a further embodiment in which the sensor holder is provided with a laser device 1701 configured to emit a beam of light 1703 for use in positioning the inspection device at a particular site on a wall or surface. The laser device may comprise a laser diode, for example, and is mounted on an arm 1705 that is coupled to the first part 303 of the sensor holder. When mounted in this way, the laser beam will be projected over the rim of the end face 305a of the sensor holder as shown in Figure 17B.

[0113] The laser beam will project a spot of light onto the wall or surface at or close to the point where the transducer head 307 will make contact as the inspection device is manoeuvred towards the surface. Thus, an operator of the drone or inspection device may use the spot of light from the laser device in guiding the device to a particular point of interest on the surface.

[0114] Figures 18A, 18B and 18C show how the arm 1705 on which the laser device 1701 is mounted may be coupled to the axle of the servo-motor. The arm 1705 has an aperture that is aligned with the channel 809 in the first part 303 of the sensor holder. With the aperture of the arm positioned over the channel 809, the second nut 805 is tightened over the arm 1705. The first part 303 of the sensor holder is then free to rotate through a small range of degrees whilst the arm 1705 remains stationary. Only when the nut 805 reaches an end of the channel 809 and the first part 303 of the sensor holder is caused to rotate through a larger number of degrees will the arm 1705 also be caused to rotate, as shown in Figure 19. By virtue of this arrangement, the laser spot will remain stationary on the wall or surface even as the sensor mount undergoes small rotations about the pitch and / or yaw axis. Meanwhile, when the sensor mount is rotated through a larger range of degrees by activating the motor, for example, the laser spot will shift to reflect the new orientation of the sensor and indicate the point at which it will contact the surface of the structure.

[0115] It will further be understood that the sensor arm 111 may be positioned underneath the body of the inspection device, or movable between the upper side and underside of the body, allowing the inspection sensor to take measurements from surfaces located beneath, as well as above or level to, the inspection device. Figures 20A-C and 21A-C show different configurations of the device with the arm 111 mounted at different points on the body. In the embodiments shown in Figures 21A and 21 B, the arm is mounted such that the transducer head 307 points directly upwards from the body of the inspection device; it will be appreciated that in these cases, the roll axis of the sensor will extend along the vertical direction, whilst the pitch axes and yaw axes both lie in a horizontal plane, parallel with the body of the inspection device.

[0116] Figures 22A and 22B show how the arm 111 may be mounted at different points on the body of the inspection device by including a mount 2201 for the arm 111 on the body of the device. The arm 111 may then be provided with a connector 2203, whereby the mount 2201 and the connector have respective mating portions that allow the arm to affix to the mount. In the example shown in Figures 22A and 22B, the mating portions take the form of corresponding screw threads on the mount 2201 and connector 2203, but it will be appreciated that this is by way of example only and other types of connector that allow the arm to be reversibly attached and detached from the body of the inspection device may also be used.

[0117] Figure 23 shows an example configuration of the arm 111 according to an embodiment. The arm includes a rear portion 2301 in which a syringe is received, the syringe acting as a reservoir for a coupling medium used in coupling the transducer head 307 to the surface under inspection. The rear portion 2301 of the arm 111 is shown in further detail in Figures 24A and 24B. Figure 24A shows the arm with the syringe 2401 located in situ. The arm 111 includes a connector 2403 that is arranged to mate with the syringe. When attached to the connector, the syringe 2401 is coupled to a pump (not shown in the figures) that is operable to pump the coupling medium from the syringe through a delivery tube to the head of the transducer 307. As shown in Figure 24B, once the supply of coupling medium has been exhausted, the syringe may be removed from the arm 111 and replenished with a fresh supply of coupling medium, before being placed back in the arm and connected to the pump.

[0118] The present invention has been described above purely by way of example. Modifications in detail may be made to the present invention within the scope of the claims as appended hereto. Furthermore, it will be understood that the invention is in no way to be limited to the combination of features shown in the examples described herein. Features disclosed in relation to one example can be combined with features disclosed in relation to a further example.

Claims

CLAIMS1. A drone for inspecting a building or structure, the drone comprising: a body having a propulsion system for manoeuvring the device relative to the building or structure; and a sensor for capturing sets of inspection data from regions of the building or structure, each set of inspection data being descriptive of a condition of a respective region, the sensor defining a pitch axis and a yaw axis; the sensor being at least partially rotatable about one or more of the pitch axis and yaw axis with respect to the body.

2. A drone according to claim 1 , wherein the sensor is at least partially rotatable about both of the pitch axis and yaw axis with respect to the body.

3. A drone according to claim 1 or 2, wherein the sensor is held in a sensor mount and is rotatable about the one or more of the pitch axis and yaw axis of the sensor by rotating the sensor mount.

4. A drone according to claim 3, wherein the sensor is spring-loaded in the sensor mount.

5. A drone according to claim 3 or 4, wherein the sensor mount comprises a first part that is rotatably coupled to the body, such that the first part of the sensor mount is rotatable about one or other of the pitch or yaw axis of the sensor with respect to the body.

6. A drone according to claim 5, wherein the sensor mount comprises a second part that is rotatably coupled to the first part, such that the second part of the sensor mount is rotatable about the other one of the pitch and yaw axis of the sensor with respect to the body.

7. A drone according to any one of claims 3 to 6, wherein the sensor mount comprises one or more magnets for coupling the sensor to a surface of the building or structure under inspection.

8. A drone according to claim 7, wherein the sensor mount has a first face arranged to contact the surface under inspection, the magnets being arranged so as to couple ofthe first face to the surface.

9. A drone according to claim 8, wherein a head of the sensor is arranged within a central region of the first face, the magnets being arranged circumferentially around the head of the sensor.

10. A drone according to any one of the preceding claims, comprising one or more motors for rotating the sensor about the pitch and / or yaw axis with respect to the body.

11. A drone according to claim 10 as dependent on any one of claims 7 to 9, wherein the one or more motors are configured to apply a torque to the sensor mount, the applied torque being large enough to overcome the magnetic coupling between the first face of the sensor mount and the surface under inspection and cause the first face to decouple from the surface.

12. A drone according to claim 11, wherein: in the absence of the motor being activated, the sensor mount is free to rotate about the pitch and / or yaw axis through a first range of degrees, the sensor mount being caused to rotate through a larger range of degrees by activation of the motor.

13. A drone according to any one of the preceding claims, wherein the sensor comprises an acoustic transducer.

14. A drone according to claim 13, further comprising a reservoir for storing a supply of coupling medium during flight of the drone.

15. A drone according to claim 14, wherein the reservoir is reversibly detachable from the body of the drone.

16. A drone according to claim 14 or 15, comprising a delivery system for delivering a portion of the coupling medium from the reservoir to the interface between the head of the acoustic transducer and the surface of the building or region under inspection.

17. A drone according to claim 16, wherein the delivery system comprises a pump operable to pump the coupling medium from the reservoir through a tube to the interface between the head of the acoustic transducer and the surface under inspection.

18. A drone according to any one of the preceding claims, wherein the body of the drone has a standard flight orientation in which the body is substantially horizontal with respect to the ground; and wherein the sensor is at least partially rotatable about one or more of the pitch axis and yaw axis whilst the body remains in the standard flight orientation.

19. A drone according to any one of the preceding claims, wherein the sensor is positioned on an arm that extends from the body.

20. A drone according to claim 19, wherein the arm is reversibly connectable to the body at one or more locations on the body and / or in one or more orientations.

21. A drone according to claim 19 or 20, further comprising a LIDAR scanner, wherein the arm is arranged such that light from the LIDAR scanner is able to pass uninterrupted between the body and the arm.

22. A drone according to any one of the preceding claims comprising one or more cleaning apparatus for wiping a surface of the building or structure under inspection prior to capturing each set of inspection data.

23. A drone according to any one of the preceding claims, further comprising a light source arranged to project a spot of light on a region of the building or structure with which the sensor is aligned.

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