Patent Description:
In the manufacture of fuselage structures, for example for aircraft or spacecraft, the surface quality is desired to meet a high standard. If the fuselage has riveted joints, for example, it is customary practice to examine the quality of the riveted joints by visual and/or tactile inspection and to subject them to selective measurement with measuring tools. For this purpose, individual riveted joints are illuminated from the side and a shadow image is used, for example, to examine whether a rivet is too deep or too high in a hole and to detect other anomalies. In addition, a finger could be run over a rivet and/or a dial gauge may be used to detect protruding or low-lying edges.

Furthermore, surface scanning devices are known that use light projection and image capture techniques to examine surface sections for specific characteristics. These devices are usually hand-held and include a foam frame that is placed on a surface section to be inspected, followed by an optical detection of the area enclosed by the foam frame. If shape deviation points are identified, information on this is stored. This is done in particular in the form of image information in which respective shape deviation points are marked accordingly.

For the inspection of longer rows of rivets on the fuselage of an aircraft or spacecraft, comprising several hundred riveted joints or more, such an inspection is time-consuming.

<CIT> relates to an inspection system for an external surface (P) of a body (A), the system comprising a flying drone connected to a base via a cable (C) supplying electricity to the drone, the drone having a chassis on which are fixed signal transmission/reception means as well as an imaging device comprising at least one optical sensor, the inspection system further comprising a control station having a central unit connected to a display device and a human-machine interface for controlling the drone and the imaging device, the central unit being further connected to a communication module configured to transmit signals to the transmission/reception means of the drone or receive signals from said means.

<CIT> relates to a tethered flight control system for a small, unmanned aircraft. The tethered flight control system can have a mobile base, a tether arm, a tether spout, and a remote-controlled winch that can hold a tether line, which can be connected to a small, unmanned aircraft. By controlling the tether line using the winch, the small, unmanned aircraft can be prevented from flying out of range or out of control. The winch can have a high-speed motor configured to remove substantially all slack from the tether line while the small, unmanned aircraft is in flight. The winch can be controlled from a hard-wired winch remote, which can take the form of a foot pedal device having one or more foot pedals. The tether line can be attached to the small, unmanned aircraft through a tether attachment apparatus, which can have a travel bar, two or more rotor protectors, and a mounting section.

<CIT> relates to a tethered drone assembly. The tethered drone assembly may be a vehicle-based tethered drone assembly system or may be a free-standing tethered drone assembly system. The tethered drone assembly has a plurality of drones each tethered by a cord. The tethered drones may hover in front of, behind or on either side of the vehicle so as to better survey the surrounding area of the vehicle. In some embodiments, a main product tank is used to supply liquids, foams, gases, powders, electrical power and/or electrical communication to the drones. A plurality of sensors located on the drones allows the drones to detect objects and environmental conditions in front of, behind or on either side of the moving vehicle in real-time and allow the vehicle to therein adjust its work accordingly. The drones may be controlled remotely by a user or may be automatically controlled by sensors.

<CIT> provides a computerized system for mapping an orchard, and a method for producing precise map and database with high resolution and accuracy of all trees in an orchard.

<CIT> describes a visual inspection arrangement comprising a robot assembly realised to move in an unconstrained manner relative to an object being subject to visual inspection, which robot assembly comprises a robot arm with an end effector realised to direct an imaging assembly at the object; a drive arrangement realised to effect a displacement of the robot assembly; a positioning system configured to track the position of the imaging assembly relative to the object; and a control unit configured to control the drive arrangement on the basis of the tracked position of the imaging assembly. The invention further describes a method of performing a visual inspection of an object.

It is thus an object of the invention to propose a system and a method with which an inspection of a surface of an aircraft or spacecraft can be conducted as quickly and reliably as possible.

This object is met by the system having the features of independent claim <NUM>. Advantageous embodiments and further improvements may be gathered from the sub claims and the following description.

A system for testing an aircraft or spacecraft surface structure is proposed, comprising at least one ground vehicle carrying at least one first inspection device, at least one hovering platform carrying at least one second inspection device, wherein the at least one first inspection device is arranged on a first arm arranged on the at least one ground vehicle, wherein the at least one ground vehicle comprises a vertical pole, wherein a transverse holding element extends from the vertical pole, wherein the at least one hovering platform is electrically connected to the at least one ground vehicle through a cable for transferring electrical power and/or data to the at least one hovering platform, wherein at least one of the vertical pole and the transverse holding element carries the cable, wherein the at least one hovering platform is flexibly held on at least one of the vertical pole and the transverse holding element through the cable or an additional component, wherein the inspection devices are configured for determining a characteristic of the aircraft or spacecraft surface structure and to identify points of shape deviation by comparison with an intended characteristic of an aircraft or spacecraft surface structure, and wherein the system is designed for successively inspecting the surface structure through the at least one first inspection device and the at least one second inspection device being arranged in different heights at the same time.

The invention lies in providing a flexible way of inspecting large surface structures by using a cooperating arrangement of ground-based inspection devices and air-based inspection devices. The ground vehicle may be considered a base of the system, to which all said inspection devices are connected. It may comprise a computing unit that is capable of receiving structure data of the inspection devices.

The at least one ground vehicle may comprise one of various different designs and is preferably capable of traveling on the ground along the surface structure. For example, it may comprise a set of wheels, on which the ground vehicle stands. At least one of the wheels is drivable to move the ground vehicle on the ground on a desired path. As an alternative, it may be placed on rails, wherein the ground vehicle may either actively travel along the rail or wherein it may be pulled and/or pushed along the rail by an external device. Still further, the ground vehicle may instead comprise a set of movable legs, through which the ground vehicle may travel along the ground. Basically, the ground vehicle may be considered a ground-based robot that is able to move on the ground along the surface structure.

The at least one first inspection device is directly attached to the ground vehicle and may be moved relative to the ground vehicle through a movable arm. This allows the first inspection device to be placed in front of several different sections of the surface structure one after another in order to inspect them. It is conceivable that the ground vehicle is capable of moving along the surface structure to a first position, stop there and move the first inspection device to a first section of the surface structure. In this state, the first inspection device inspects the respective section and stores and/or sends data, e.g., to the above-mentioned computing unit. Afterwards, the first inspection device may be moved to a directly adjacent section in order to inspect it. It is conceivable that after inspecting a set of adjacent sections or a pattern of sections in reach of the arm at the fixed position of the ground vehicle, the ground vehicle may be moved further along the surface structure. There, the first inspection device is able to inspect a subsequent number of sections or a pattern of sections in reach of the arm in the actual position of the ground vehicle.

Since the ground vehicle is ground-based, it is conceivable that the at least one first inspection device is dedicated for inspecting the surface of a lower part of the surface structure up to a certain height, wherein the at least one second inspection device is dedicated for inspecting higher portions of the surface structure. The hovering platform may comprise lifting device, such as a set of propellers and electric motors, which are capable of lifting the hovering platform and thus carrying the at least one second inspection device. The hovering platform should be able to move to a desired position and maintain it during the inspection of a certain section of the surface. This allows to eliminate a complicated, heavy and expensive actuation device for moving the at least one second inspection device into larger heights with a required positional precision. By supplying the hovering platform with electrical power from the ground vehicle it may be dimensioned with a considerably low weight and a virtually unlimited hovering time. By connecting the at least one hovering platform to the ground vehicle via a data cable, processing power can be provided inside the ground vehicle. Thus, the respective hardware for navigation tasks, data processing, data analyzing and similar can be arranged inside the ground vehicle, thus reducing the weight of the at least one hovering platform even further.

By holding the cable in the vertical pole and/or the transverse holding element and by flexibly holding the at least one hovering platform on the vertical pole and/or the transverse holding element, the hovering platform is reliably prevented from a descent upon a malfunction. Due to its light weight it may simply be restrained by the cable and/or the additional component. It is thus safely prevented from descending below a certain altitude. By providing the vertical pole and coupling the transverse holding element to it, the cable can be guided roughly in or slightly below the desired flight height. Furthermore, the transverse holding element can be arranged in a sufficient height clearly above the ground, to allow a vertically flexible position of the hovering platform and still reliably arrests the hovering platform in a sufficient height when it experiences an impaired generation of lift.

The inspection devices may be implemented in various different ways. Preferably, as explained in the introduction, it may be designed as an optical scanning device and is designed to check certain characteristics without contact by means of capturing and evaluating an image of a projected pattern of visible light. Such a device is known and commonly used for inspecting aircraft surface structures. However, mechanical scanning devices or scanning devices based on non-visible light are also conceivable.

In an advantageous embodiment, the ground vehicle comprises a reeling drum for the cable, wherein the reeling drum is adapted for providing a tensioning force onto the cable. The reeling drum may be provided for receiving and storing the cable. It may be comparable to a common cable drum which may, if desired, be encapsulated in a housing. To avoid an excessive free cable length outside the reeling drum, i.e., between the transverse holding element and the hovering platform, the reeling drum is capable of constantly retracting the cable. However, the tensioning force should not be excessive in order to still allow the hovering platform to pull the cable out of the reeling drum when moving relative to the ground vehicle. The tensioning force should be dimensioned in a way that the reeling drum is just able to maintain a desired tightness of the cable.

In an advantageous embodiment, the reeling drum is adapted for arresting the cable upon an excessive pulling force from the respective hovering platform or upon power supply interruption of the cable and/or the respective ground vehicle. Thus, the reeling drum has an active brake that in the event of a malfunction of the hovering platform can be activated to hold the hovering platform through the cable. The excessive pulling force from the respective hovering platform may directly result from the hovering platform experiencing an impaired generation of lift. As an alternative or in addition thereto, the power supply to the hovering platform may be electrically connected to an electric brake or arresting mechanism of the reeling drum. For example, the reeling drum is released if the power supply is active. If the electrical power is interrupted, a brake mechanism of the reeling drum may be brought into an arresting state through a resilient element, in which the reeling drum is arrested. Thus, once the hovering platform is not supplied with electrical power, leading to a descent, the reeling drum would automatically be arrested. The brake mechanism may comprise an electromagnetically supported pin in a first element of the reeling drum, which is retracted from a hole in a second element of the reeling drum, which is movable relative to the first element. The pin is retracted from the hole through the electrical power supply and is pushed into the hole by a spring if the electrical power supply is interrupted.

In an advantageous embodiment, the transverse holding element comprises an elongated beam having a first end connected to the vertical pole and a second end facing away from the vertical pole, wherein the cable is held at least on the second end and comprises a transfer section extending to the hovering platform. The transfer section of the cable is a free section of the cable that extends between the hovering platform and an outer end of the transverse holding element. The elongated beam allows to place a holding point for the cable and for the hovering platform laterally away from the ground vehicle. This not only increases the operation radius of the hovering platform, but also prevents an impact of the hovering platform on the ground vehicle in the case of a malfunction.

In an advantageous embodiment, the transverse holding element comprises a chain of swivably coupled, actively articulated elongated beams, wherein the cable is routed along the chain of articulated beams, and wherein the hovering platform is held at an outer end of the chain of articulated beams through the cable or a rope as the additional component. The chain of actively articulated elongated beams allows a higher flexibility in positioning the cable relative to the ground vehicle and the hovering platform. For example, an increased flexibility in different operational altitudes for the hovering platform is provided.

In an advantageous embodiment, the articulated beams are actively moved to follow the motion of the respective hovering platform. They can be moved by small electric actuators, such as step motors. Since the articulated beams do not need to provide high forces, their articulation can be achieved by simple, inexpensive and compact devices.

In an advantageous embodiment, the at least one hovering platform may simply be adapted for providing a lift force, wherein the chain of articulated beams is adapted to guide the at least one hovering platform to a required spatial position. Thus, the respective hovering platform may be realized with even further reduced costs.

In an advantageous embodiment, the at least one ground vehicle comprises two ground vehicles, wherein the transverse holding element comprises a horizontal rope or wire extending between the vertical poles of the two ground vehicles, and wherein the at least one hovering platform is coupled with the horizontal rope or wire through a safety rope or wire loop. The horizontal rope may be arranged above the surface structure to be scanned and the hovering platform can more freely move in a lateral direction. However, to avoid descending below a certain altitude, they are loosely coupled with the horizontal rope through safety rope or a safety wire loop.

In an advantageous embodiment, a plurality of hovering platforms is coupled with the horizontal rope or wire, and wherein the safety rope or wire loop size for at least one of the hovering platforms is smaller than the size for at least another one of the hovering platforms according to a predetermined height of the surface structure to be placed underneath the safety rope or wire loop. Thus, the size of the safety rope loop or the safety wire loop is chosen according to the intended position relative to the surface structure to be scanned.

In an advantageous embodiment, the height of the vertical pole is adjustable. This may be done actively, for example through a linear gear drive, a spindle drive, an inflatable telescopic tube as a vertical pole or by passive means, such as a telescopic pipe with a latching mechanism that allows to latch one of the telescopic tube members in different positions of another telescopic tube member. In doing so, the height of the vertical pole is simply adjustable to the surface structure to be scanned, e.g., for different types of spacecraft or aircraft.

In an advantageous embodiment, the vertical pole is actively or passively rotatable. Thus, the vertical pole may swivel about its vertical axis to simplify the process of following the hovering platform's motion. As an alternative to this, the transverse holding element may be supported on the vertical pole in a rotatable manner, i.e., the holding element itself may rotate around the vertical pole about the vertical pole axis.

In an advantageous embodiment, the at least one hovering platform comprises a plurality of lift producing, electrically driven propellers with a substantially vertical thrust axis. Thus, common designs of multi-copters may be used, which are commercially available with precise flight characteristics.

In an advantageous embodiment, the at least one ground vehicle comprises a control unit for the at least one hovering platform to individually control the lift producing propellers to move the at least one hovering platform to a desired spatial position and maintain the position for a predetermined amount of time. Thus, the individual hovering platforms do not require dedicated flight control electronics, may be realized in the form of inexpensive replaceable devices and may be combined with more or less additional hovering platforms depending on the size of the surface structure to be scanned.

In an advantageous embodiment, the vertical pole is a hollow tube having a length of at least <NUM> and is made from a fibre reinforced plastic material and/or a metallic material. As explained above, the vertical poles may even be adjustable in length. Since the vertical poles do not need to provide a distinct structural stability, they may comprise a rather small diameter and may be flexible. It is conceivable to let the vertical poles extend to a height of <NUM> to <NUM>, while the diameter may be as small as <NUM>,<NUM> to clearly less than <NUM>, e.g., in a region of <NUM> to <NUM>. They may be made from Aluminium or carbon fiber reinforced plastic. The vertical poles may be made from a plurality of sections, e.g., four sections having a length of about <NUM> each. They may be sticked together to create the vertical pole. However, they may be telescopic and comprise latching holes in a desired distribution.

In analogy, the elongated beams or the articulated elongated beams mentioned above may be created with the same material and suitable dimensions.

In an advantageous embodiment, the ground vehicle comprises a weight of at least <NUM>. Preferably, the center of gravity of the ground vehicle is as close to the ground as possible. It is assumed that the ground vehicle, which may be based on an industry standard ground robot, may have a weight of above <NUM> including a set of rechargeable batteries, a sturdy chassis, enclosure and drive arrangement. By having such a weight, the ground vehicle constitutes a sturdy base that does not tip over in case of a hovering platform being held by the transverse holding element. It is conceivable that the hovering platform weigh clearly less than <NUM> including the inspecting device.

In an advantageous embodiment, the ground vehicle comprises at least one landing platform for receiving and storing a hovering platform before or after use of the system. The mobility of the system can be maintained. It is possible to let the ground vehicle move to and away from the surface structure before and after completing the process of scanning or inspecting it. It is possible to let the ground vehicle dock in a docking station for recharging, wherein the ground vehicle may autonomously move to the surface structure after recharging, while the at least one hovering platform is safely parked on the respective landing platform.

In the following, the attached drawings are used to illustrate exemplary embodiments in more detail. The illustrations are schematic and not to scale. Identical reference numerals refer to identical or similar elements. They show:.

<FIG> shows a system <NUM> for scanning or inspecting an aircraft or spacecraft surface structure. The system <NUM> comprises a ground vehicle <NUM> having a plurality of wheels <NUM> for standing on the ground. At least one of the wheels <NUM> is driven, exemplarily by an electric motor, which is not shown in detail herein. The ground vehicle <NUM> comprises a frame structure <NUM>, which is designed to receive a replaceably held rechargeable battery <NUM>. Furthermore, a control unit <NUM> is attached to the ground vehicle <NUM> and serves for several functions that are explained further below.

At a top side <NUM> of the ground vehicle <NUM>, a first arm <NUM> having two arm members 18a and 18b is provided, wherein the first arm <NUM> carries a first inspection device <NUM>. The first arm <NUM> comprises a plurality of joints <NUM>, which allow to move the first inspection device <NUM> in several directions. The ground vehicle <NUM> may move along the respective aircraft or spacecraft surface structure, arrest at a desired position and scan the surface structure section by section with the first inspection device <NUM>. Data that is generated by the first inspection device <NUM> is fed into a computing unit, which is not shown in detail herein, but may be arranged inside the ground vehicle <NUM> or in an external apparatus. Since the aircraft or spacecraft surface structure comprises a rather large height, the first inspection device <NUM> as well as the first arm <NUM> are designed to primarily scan a lower half of the surface structure.

At the top side <NUM> of the ground vehicle <NUM>, a vertical pole <NUM> is provided, which clearly extends above the first arm <NUM>. A transverse holding element in the form of an elongated beam <NUM> is provided, which has a first end <NUM> and a second end <NUM>. The first end <NUM> directly adjoins the upper end of the vertical pole <NUM> and extends substantially in a horizontal alignment from the vertical pole <NUM>. For increasing the stability, a diagonal stiffening beam <NUM> is arranged between the elongated beam <NUM> and the vertical pole <NUM>.

A hovering platform <NUM> having a plurality of electrically driven propellers <NUM> and carrying a second inspection device <NUM> is provided and electrically connected to the ground vehicle <NUM> through a cable <NUM>. The cable <NUM> is routed along the elongated beam <NUM> and the vertical pole <NUM>. The hovering platform <NUM> is supplied with electrical power through a transfer section <NUM>, i.e., a section that extends from the second end <NUM> to the hovering platform <NUM>, of the cable <NUM> and, preferably, data generated by the second inspection device <NUM> is transferred to the ground vehicle <NUM> through the cable <NUM>.

The hovering platform <NUM> is adapted to lift the second inspection device <NUM> to a desired altitude/height and a desired position relative to the ground vehicle <NUM>. As it does not need to carry its own battery, it may be designed as lightweight as possible. The second inspection device <NUM> is dedicated for scanning an upper half of the surface structure and, depending on the size of the structure, also lateral sides of it. Hence, the system <NUM> is adapted for scanning a surface structure by at least two inspection devices <NUM> and <NUM> in cooperation.

A landing platform <NUM> is provided above the top surface <NUM> of the ground vehicle <NUM>, which allows to land and park the hovering platform <NUM>. In addition, a reeling drum <NUM> is provided underneath, on or above the top side <NUM>, receives the cable <NUM> and releases length increments of the cable <NUM> upon a pulling force or retracts length increments upon the lack of a pulling force. If the hovering platform <NUM> moves relative to the second end <NUM> of the elongated beam <NUM>, the free length of the cable <NUM> is thus automatically adjusted.

If the hovering platform <NUM> experiences a malfunction, it may not be able to provide a sufficient lifting force to maintain a desired altitude and may descent. Due to mechanical connection to the cable <NUM>, the hovering platform <NUM> will be held by the arrangement of the vertical pole <NUM> and the elongated beam <NUM> through the cable <NUM>. To further improve this, the reeling drum <NUM> could be designed comparable to a seat belt retractor in a car that arrests upon a sudden pulling force on a belt. Hence, if the hovering platform <NUM> descents from its operational altitude, it will suddenly pull on the cable <NUM>, leading the reeling drum <NUM> to arrest and hold the hovering platform <NUM> clearly above the ground.

It's conceivable, that the control unit <NUM> is capable of controlling hovering platform <NUM> to maintain a stable attitude and altitude. Consequently, the hovering platform <NUM> only needs to be equipped with usual attitude and altitude sensors, but does not necessarily need to comprise expensive control electronics. A failed hovering platform <NUM> may thus be replaced with clearly limited costs.

The arrangement of the vertical pole <NUM> and the elongated beam <NUM> does not require a high mechanical stability or rigidity, since only the cable <NUM> needs to be mechanically held. In the unlikely case of a failure of the hovering platform <NUM>, however, it is tolerable to elastically deform this arrangement. The rigidity or stability of this arrangement is not crucial for achieving a positioning precision of the hovering platform <NUM> at all.

It is conceivable that the vertical pole <NUM> is rotatably supported on the ground vehicle <NUM> to adjust its alignment when the hovering platform <NUM> changes a relative position to the ground vehicle <NUM>. It is possible to provide a passive rotatability of the vertical pole <NUM>, but also an active movability through an actuator.

In <FIG> the system <NUM> is slightly modified in that the elongated beam <NUM> as the transverse holding element is replaced by a second arm <NUM> with a chain of swivably coupled, actively articulated elongated beams <NUM>. They comprise three joints <NUM> and an outer end <NUM>. A rope <NUM> as an additional component is attached to the outer end <NUM> and is mechanically coupled with the hovering platform <NUM>. The cable <NUM> is routed along the vertical pole <NUM> and second arm <NUM>. The second arm <NUM> may actively follow the position of the hovering platform <NUM>, or, as explained below, may even actively guide the hovering platform <NUM>.

In case of a malfunction of the hovering platform <NUM>, the second arm <NUM> may simply maintain its position and the hovering platform <NUM> will held by the rope <NUM> at the outer end <NUM> of the second arm <NUM>. Again, the articulated and elongated beams <NUM> do not require a high structural stability or a set of strong actuators, since the second arm <NUM> only needs to carry the cable <NUM>. If the hovering platform <NUM> experiences an impaired generation of lift and descents, the second arm <NUM> elastically deforms, but substantially maintains its position to prevent the hovering platform <NUM> from descending below a certain altitude.

The hovering platform <NUM> may be realized in an even further cost-effective way in that it simply provides a lifting function. The second arm <NUM> is then controlled by the control unit <NUM> to move the operating hovering platform <NUM> to a desired position for scanning or inspecting the surface structure. Then, the hovering platform <NUM> requires less sensors to operate.

In a modified system <NUM> shown in <FIG>, two ground vehicles <NUM> are provided, which each comprise a vertical pole <NUM>, between which a transverse holding element in form of a horizontal rope <NUM> extends. Thus, the arrangement of vertical poles <NUM> and the horizontal rope <NUM> embrace a surface structure <NUM> to be scanned. The rope <NUM> may exemplarily be attached to both vertical poles <NUM>. The ground vehicles <NUM> would then need to be controlled to move in a cooperative way to maintain the horizontal rope <NUM> comprising a sufficient tension. Thereby, they may move along the surface structure <NUM> at the same time and in the same direction. However, in this exemplary embodiment, rope reeling devices <NUM> are provided, which hold and release the horizontal rope <NUM> and maintain a certain tension of it. Thus, the horizontal rope <NUM> will always remain in a sufficient height above the surface structure <NUM> to be scanned.

In this exemplary embodiment, two hovering platforms <NUM> are provided, wherein each hovering platform <NUM> is connected to a one of both ground vehicles <NUM>. The cable <NUM> for each hovering platform <NUM> is held by the respective vertical pole <NUM> and extends to the respective hovering platform <NUM>.

Both hovering platforms <NUM> are loosely coupled to the horizontal rope <NUM> by individual wire loops <NUM>, which are wound around the horizontal rope <NUM> and connected to the hovering platforms <NUM>. The sizes of the loops <NUM> are chosen to ensure a sufficient freedom of motion for the hovering platforms <NUM>, but to hold the hovering platforms <NUM> in a failure case above the ground vehicles <NUM> and above the surface structure <NUM>. To prevent the horizontal rope <NUM> from moving down to the surface structure <NUM>, the rope reeling devices <NUM> comprise a self-arresting function, similar to a belt retractor in a car. Thus, in case a sudden tension acts onto the horizontal rope <NUM>, the rope reeling devices <NUM> arrest and the hovering platforms <NUM> can be safely held.

Claim 1:
A system (<NUM>, <NUM>, <NUM>) for scanning or inspecting an aircraft or spacecraft surface structure (<NUM>), comprising:
at least one ground vehicle (<NUM>) carrying at least one first inspection device (<NUM>),
at least one hovering platform (<NUM>) carrying at least one second inspection device (<NUM>),
wherein the at least one first inspection device (<NUM>) is arranged on a first arm (<NUM>) arranged on the at least one ground vehicle (<NUM>),
wherein the at least one ground vehicle (<NUM>) comprises a vertical pole (<NUM>),
wherein a transverse holding element (<NUM>, <NUM>, <NUM>) extends from the vertical pole (<NUM>),
wherein the at least one hovering platform (<NUM>) is electrically connected to the at least one ground vehicle (<NUM>) through a cable (<NUM>) for transferring electrical power and data to the at least one hovering platform (<NUM>),
wherein at least one of the vertical pole (<NUM>) and the transverse holding element (<NUM>, <NUM>, <NUM>) carries the cable (<NUM>),
wherein the at least one hovering platform (<NUM>) is flexibly held on at least one of the vertical pole (<NUM>) and the transverse holding element (<NUM>, <NUM>, <NUM>) through the cable (<NUM>) or an additional component (<NUM>, <NUM>),
wherein the inspection devices (<NUM>, <NUM>) are configured for determining a characteristic of the aircraft or spacecraft surface structure (<NUM>) and to identify points of shape deviation by comparison with an intended characteristic of an aircraft or spacecraft surface structure, and
wherein the system (<NUM>, <NUM>, <NUM>) is designed for successively inspecting the surface structure (<NUM>) through the at least one first inspection device (<NUM>) and the at least one second inspection device (<NUM>) being arranged in different heights at the same time.