Patent Description:
Flying drones having helices or rotors present risks of injury of surrounding persons and risks of damage in case of collisions with obstacles. In particular, flying drones which are used to inspect cluttered and confined spaces. In addition, such flying drones progress in industrial environments often hindered with machines and equipment. These obstacles cannot always be detected and escaped before a contact. Obstacles such as buildings and any other urban constructions also represent risks of collisions. Such collisions may damage the flying drones, or parts of the flying drones, in particular their rotors. It is thus usual to protect the flying drones against chocs.

For protecting both the flying drones and the surrounding users and equipment, protective cages are usually arranged around the flying drones. The document <CIT>, for example, describes a protective cage for such a flying drone. The cage and the flying drone form together an ensemble that can be folded and unfolded. Folding and unfolding the cage and the drone necessitate several steps to secure the ensemble. Also, when the cage is damaged after a choc for example, it needs to be dissociated from the corresponding drone to be repaired, which necessitates time and additional manipulations. Furthermore, the cage is specifically designed for a given flying drone and cannot easily be adapted to other flying drones. A protective cage represents an additional weight for the flying drone, which impacts its energy consumption and its agility. It is thus a continuous challenge to provide light protective cages, which however provides sufficient protection while being cost effective, easy to manufacture and to maintain. Other protective cages are also disclosed in <CIT> and <CIT>.

There is thus room to improve the protective cages for the flying drones.

An aim of the present invention is the provision of a protective cage, adapted for a flying drone, which overcomes the shortcomings and limitations of the state of the art. It is in particular an objective to provide an improved cage which is light and still efficient against chocs and injuries. It is also an aim to provide a protective cage which can easily be separated from the drone and/or adapted to various drones. To this extend, it is aimed at providing a protective cage which is foldable, independently from the drone it protects.

Another aim of the invention is the provision of a method of protection of a flying drone against collisions and to prevent user's and drone damages.

According to the invention, these aims are attained by the object of the attached independent claims and detailed in the dependant claims.

In particular, the protective cage <NUM> of the present disclosure is adapted for an Unmanned Aerial Vehicle (UAV) (i.e. a drone). This cage protects the rotors and other elements of the vehicle from physical damage resulting from collisions and/or falls. The cage structure allows a safer interaction between the vehicle and the surrounding environment. The cage should therefore be materially dense enough to offer protection while not impeding the vehicle's aerodynamics. Also, it must be able to deal with impacts, decelerating the body without inferring damage. Finally, in order to reduce the vehicle flight energy expenditure, the weight of the cage must be kept at a minimum. The cage needs also to be cost effective and easy to maintain.

The protective cage of the present disclosure is detachable from the vehicle, so that it can be replaced in case of heavy damage. Moreover, it is foldable or can be flattened so that its storage volume is significantly reduced compared to its deployed volume. This also facilitates the transport of spare cages, e.g. when operating in remote harsh environments.

The protective cage of the present disclosure can be substantially folded or flattened. The cage offers protection to the rotors and other vehicle elements located inside the cage volume. The structure itself is made of repeating thin ribs connected by a rope mesh, thus creating a strong yet lightweight structure. The ribs are connected at both poles by a ring and an indexing cap, hence forming a cage when unfolded. Whereas the ring prevents the ribs from moving radially, the indexing cap locates the ribs at specific angles. A closing part connects the two end ribs together, thus forming a closed cage. When the cage is in the deployed position, the ropes prevent the ribs from deforming, or limit their deformation, and act as energy absorbers to handle collisions.

The deployment of the cage from its storage position up to the fully opened position includes rotating the ribs around their retaining pole rings. Then the closing part and caps are installed. The rope mesh stays at all time fixed to the ribs.

To guarantee a mechanical stiffness of the structure, relative motion of the rope mesh with respect to the ribs is to be prevented. This is achieved by clamping the rope at least at some nodes, i.e. where the rope crosses a rib. Moreover, the rope mesh forms a criss-cross pattern to improve the mechanical response.

Lateral rods might be added to reinforce the tension of the rope and enhance collision resilience property. Such rods are optional and might be removable if not necessary. They can be inserted between adjacent ribs and thus maintain the distance between two adjacent ribs, including during a collision.

With respect to what is known in the art, the invention provides the advantage of a light and modular protection cage, easy to handle and adaptable to several different situations.

Exemplar embodiments of the invention are disclosed in the description and illustrated by the following drawings :.

With reference to <FIG>, <FIG> and <FIG>, the protective cage <NUM> according to the present disclosure comprises several ribs <NUM> having a general curved or arcuate shape. Once deployed, the ribs <NUM> of the protective cage <NUM> define an internal space wherein a drone <NUM> can be arranged, as better shown in <FIG>. The ribs <NUM> are combined together at their extremities 141a, 141b, by means of a corresponding ring 106a, 106b. To this end a ring connexion point is arranged at both extremities of each of the ribs <NUM> wherein the ring is inserted. <FIG> shows an example of such an arrangement. The ring connexion points are through holes. In this specific arrangement, the rings 106a, 106b are not removable from the corresponding extremities 141a, 141b of the ribs <NUM>. The rings 106a, 106b are however free to slide in the through holes of the rib extremities 141a, 141b so as to allow their folding and deployment moves. One of the rib extremities 141a, 141b, or both of them may however comprise a removable attachment point such as a snap hook, a spring hook, or other equivalent fast and safe removable fixation means. In this case, a rib <NUM> may be removed from the corresponding ring 106a, 106b. This facilitates its replacement in case of damages, or if the shape or size of some ribs <NUM> should be changed and better adapted to the drone <NUM>.

The ribs <NUM> preferably adopt an arcuate shape so that their extremities 141a, 141b are facing each other. The concave side is here considered as the inward or inside part of the ribs, the convex side is here considered as the outward or outside part of the ribs. The ribs <NUM> define a virtual axis around which they can rotate to move from a folded position to a deployed position. In other words, the two opposites rings 106a, 106b also define such a virtual axis. Such an axis has a vertical orientation, meaning that, when the flying drone is in use and normally oriented, surrounded by the protective cage, the virtual axis passing by the extremities 141a, 141b of the ribs <NUM> is vertical, or substantially vertical. It is also parallel to the rotation axis of the rotors of the flying drone <NUM>.

The ribs <NUM> are substantially flat, with a low thickness, so as to limit the hindrance once all the ribs <NUM> are folded one against each other. They may have a width higher than their thickness. The width of the ribs <NUM> determines the resistance of the ribs <NUM> in case of collisions against an obstacle. Depending on the needs, the thickness of the ribs <NUM> may be comprised between around <NUM> and around <NUM>. The width may be comprised between around <NUM> and around <NUM>. The proper width of the ribs <NUM> may be determined according to the number of ribs <NUM> of the cage <NUM>, the speed of the drone, the weight of the ensemble comprising the drone, the cage, and the payload of the drone, the resistance of the material of the ribs <NUM> and any other suitable parameters. The thickness of the ribs <NUM> is preferably homogenous along their length from one of their extremities 141a to the opposite one 141b. Also, the ribs <NUM> have a linear thickness. Then, they can be stacked in a compact and flat arrangement once folded. The width of the ribs <NUM> may be non-homogenous along their length. For example, the width of the ribs <NUM> may be larger at their central portion compared to their peripheral portion. Alternatively or in addition, the ribs <NUM> may have a given geometry, which is for instance adapted to allow fixing additional elements or accessories. The damping of the chocs is thus efficient thanks to the larger width at the central portion of the ribs <NUM>, while the weight remains light due to a decreased width at the peripheral portions of the ribs <NUM>.

All the ribs <NUM> are preferably identical, meaning that their shape and size are identical. In that case, they form a symmetrical space. Alternatively, some ribs <NUM> may have a different shape. For example, ribs which are close to the rotors of the drone <NUM> may have an adapted shape protecting the rotors. In case a payload should be delivered, the shape of the ribs <NUM> may also be adapted according to the volume and position of the payload. In that case, the thickness may still remain the same for all the ribs <NUM> so that they can be compacted in a folded stage.

The ribs <NUM> are preferably flexible and tough, so as to resist the chocs in case of collisions. They are thus preferably made in a reinforced plastic polymer, such as a thermoplastic polymer, adapted to resist the energy of a choc and preserve the drone <NUM> from any damages. Other suitable damping materials may be used. For lightness and resistance, the ribs may also be made of, or comprise, carbon fibres or other inorganic fibres, or composite materials.

Along their length, the ribs <NUM> comprise string connexion points 111a, 111b, 111c, 111d, 111e, 111f, adapted to insert a string <NUM>. The string connexion points of the ribs <NUM> are preferably facing each other so that all the corresponding string connexion points are arranged in a same plane. Such a plane may be orthogonal to the virtual axis above-mentioned, passing to the opposite rings 106a, 106b. Depending on the needs, <NUM> to more than <NUM> series of string connexion points can be provided, for instance, <NUM> to <NUM> or <NUM> to <NUM> series of connexion strings, forming the same number of parallel planes. For example, <FIG>, <FIG> and <FIG> show <NUM> series of string connexion points 111a, 111b, 111c, 111d, 111e, 111f. In case the space between <NUM> parallel rings should be reduced, more series of string connexion points may be arranged. A string connexion point may denote a through hole. In that case, a given string <NUM> is preferably inserted into the through holes of a given series of contiguous ribs <NUM>, meaning that it follows a given plane, once the ribs <NUM> are deployed. It is however not excluded that a ring <NUM> passes through holes of contiguous ribs <NUM>, which do not belong to the same plane. It is also not excluded that two rings <NUM> cross each other between two contiguous ribs <NUM>. Preferably, one through hole of the ribs receive only one string <NUM>. It may however be envisaged that two strings <NUM> pass through a given hole of the ribs <NUM> and cross therein to reach holes of other planes at contiguous ribs <NUM>. Whether the strings <NUM> are arranged parallel to each other or not, it is understood that they join all the ribs <NUM> and provide a protective field between the ribs <NUM>. The strings <NUM> thus also denotes a rope mesh.

For an improved adaptability of the protective cage, as well as for lighten the protective cage <NUM>, a large number of through holes may be provided on each rib <NUM>. Such a large number may be for example comprised between <NUM> and <NUM> or more. The weight of the protective cage <NUM> is then lower, while the resistance against chocs is not impaired or not significantly impaired. In addition, the user can select the series of through holes where the strings <NUM> are inserted, depending on the specific needs. For example, only few rings <NUM> may pass through the holes <NUM>, letting most of them unused. On the contrary, when a very dense protection appears necessary, all the through holes of the ribs may be crossed by a ring <NUM>.

The strings <NUM> joining the ribs <NUM> are preferably non elastic, or with a reduced elasticity, so as to rigidify the cage. When the cage <NUM> is fully deployed, the strings <NUM> are straight and no longer loose. Alternatively, the string may exhibit enough elasticity to be extended and guarantee that take a strait position between the ribs <NUM> when they are fully deployed and locked in the deployed position by the means of the closing part <NUM>, which will be better described below.

According to an embodiment, the strings <NUM> are fixed only to the first and the last rib <NUM> and free to slide through the holes 111a, 111b, 111c, 111d, 111e, 111f of the ribs <NUM> which are between the first and the last ribs. In that case, the first and the last ribs <NUM>, once fully deployed, put the rings <NUM> in tension while allowing the ribs in between to have nonspecific relative angular positions. The angular position of the ribs in between may be determined by means of an indexing cap <NUM> at the extremities 141a, 141b of the ribs <NUM>. Such an indexing caps <NUM> will be better described below.

According to another embodiment, the rings <NUM> are clamped at each through hole <NUM> of the ribs <NUM>. The clamping may be performed by means of an adequate clamping means (not shown) allowing to removably trap the rings <NUM> against the corresponding ribs <NUM>. Such clamping means may comprise a lever which can be actuated by the user to clamp and release the strings <NUM>. Using such a removable means, the relative angular position of the ribs <NUM> may be easily adapted. For example, some ribs may need to be closely arranged while more space is allowed between other ribs. Such special arrangement may depend for instance on the drone itself, the number, the position and size of its rotors, or any other parameters.

Alternatively, the strings <NUM> are definitely clamped or fixed on the ribs <NUM>. They may be glued or welded on the ribs <NUM>. In that case, the relative angular position of the ribs <NUM>, at the deployed position, is predetermined and cannot be easily modified. In that case, although it is preferable that the strings <NUM> cross the ribs <NUM> for a better resistance, it is understood that the through holes of the ribs <NUM> may be absent and the rings <NUM> are simply fixed on the surface of each rib <NUM>.

The through holes 111a, 111b, 111c, 111d, 111e, 111f of the ribs <NUM>, as defined above, necessitate to slide the strings <NUM> from one rib <NUM> to the adjacent one, from the first one until the last one. According to an alternative, the string connexion points 111a, 111b, 111c, 111d, 111e, 111f of the ribs <NUM> may be removable or releasable attachment points such as a snap hooks, spring hooks, or other equivalent fast and safe removable fixation means. According to such a configuration, the strings <NUM> can easily be clipped within the hook, and optionally clamped. As for the corresponding ring connexion points of the extremities 141a, 141b of the ribs <NUM>, such arrangement allows an easy replacement of a rib if needed. In that case, the ribs to be exchanged may be removed from the rest of the protective cage <NUM> by merely disconnecting the strings <NUM> and the two opposite rings 106a, 106b, without removing all the strings <NUM> from all the ribs <NUM>.

The number of ribs <NUM> may vary according to the needs. Four ribs <NUM> may be enough, for example in case of a helicopter having only one rotor at a central position. Otherwise, <NUM>, <NUM>, or more than <NUM> ribs <NUM> may be necessary. The ribs <NUM> may have a regular angular shift, providing a symmetrical arrangement. Alternatively, the relative angular position of the ribs <NUM> may be non-regular. This can be advantageous to concentrate the ribs at the most sensitive positions round the drones, while limiting the global weight and avoiding unnecessary ribs at other positions.

Some or all the ribs <NUM> may be provided with a lug <NUM> at a position close to their extremities. A position close to the extremity of the ribs means for example at a distance from the extremity lower than <NUM>/<NUM>, <NUM>/<NUM> or <NUM>/<NUM> of the rib length depending on the needs or the shape of the ribs. Such a lug <NUM> allows to stabilise the cage <NUM> once landed on floor. The lug <NUM> is thus preferably arranged close to one extremity 141b, of the ribs <NUM>, predetermined to be at a lower position when the drone lands. It is however not excluded that two lugs <NUM> are arranged symmetrically close to both extremities 141a, 141b of the ribs <NUM> so that no mistake is done when placing the ribs <NUM> on the rings 106a, 106b. It is understood that such lug <NUM> is oriented outward the corresponding rib <NUM> compared to the internal space the rib defines.

Some or all the ribs <NUM> comprise at least one attachment point 121a, adapted to removable connect the protective cage <NUM> to a flying drone <NUM>. Depending on the case, the ribs may be directly linked to the drone <NUM> by means of this at least one attachment point 121a or linked to the drone through an intermediate support <NUM>. It is noted that this attachment points allow to easily disconnect and connect the protective cage <NUM> to a drone <NUM>. They are thus accessible by the user from outside the protective cage <NUM>.

In an embodiment a support <NUM>, comprising a support body <NUM> and a fixation means <NUM> adapted to receive a drone <NUM>, also comprises support arms <NUM>, the extremity of which can be connected to some ribs <NUM> at the corresponding attachment point 121a. To this end, the angular orientation of the support arms <NUM> can be adapted to coincide with one of the attachments point 121a of the ribs <NUM>. Alternatively, the angular position of the ribs <NUM> may be easily adapted to coincide with the support arms <NUM>. For example, the attachment point 121a, may comprise a recess in the width of the corresponding ribs <NUM> to receive the corresponding support arm <NUM>. In addition, a clamping means may be provided, allowing the user to firmly connect the support <NUM> to the protective cage <NUM>. Alternatively or in addition, the extremity of the support arms <NUM> may be provided with a ring surrounding the ribs to which the support arm <NUM> is attached. Such a ring can easily be open and close from outside the protective cage <NUM> by the user.

According to another embodiment, the at least one attachment point 121a comprises a lug having a flat surface and oriented inward the space defined by the protective cage <NUM>. The support <NUM> comprises a support connexion means <NUM>, the dimensions of which correspond to the dimensions of the internal space defined by the protective cage <NUM> at the attachment point 121a, once the ribs are deployed. The support connexion means <NUM> may be placed on the flat surface of the lug 121a of the ribs <NUM>. When moving the ribs <NUM> from their folded position to the deployed position around the support connexion means <NUM>, their attachment point 121a slide along the support connexion means <NUM> so as to immobilise it within the protective cage <NUM>. According to this arrangement, no additional clamping means are necessary. The support connexion means <NUM> has a circular geometry allowing such a sliding of the ribs during their deployment or folding moves. It can take the form of a circular rail linked or integral to the support arms <NUM> of the support <NUM>. An additional lug 121b is preferably provided, facing the previous lug 121a, having also a flat surface facing the flat surface of the first lug 121a. The space between the two lugs 121a, 121b corresponds to the thickness of the support connexion means <NUM> and are adapted to slide around it. Once the cage is deployed, the two opposite lugs 121a, 121b clamp the support connexion means <NUM> and immobilise the support within the internal space of the cage <NUM>. It is understood that the two opposite lugs 121a, 121b can be replaced by a recess in the width of the ribs, adapted to surround the support connexion means <NUM>.

The attachment points 121a, 121b, may define one predetermined emplacement for the support <NUM> of the drone <NUM> in the internal space of the cage <NUM>. Additional attachments points 121a, 121b may be distributed along the ribs <NUM> to allow positioning a support <NUM> at various height in the internal space of the cage <NUM>. For example, some attachment points may be provided at the middle of the ribs <NUM>, so that the support <NUM> is positioned at a central position in the internal space of the cage <NUM>. Attachments points may be provided at higher positions such as <NUM>/<NUM> or <NUM>/<NUM> of the height of the cage <NUM> so as to arrange enough space for the payload below the drone <NUM>. Attachment points may be provided below the middle of the ribs <NUM> such as <NUM>/<NUM> or <NUM>/<NUM> of the height of the cage <NUM>. The gravity centre of the ensemble can thus be adapted for a better flyability.

A support <NUM> is preferably used to connect a flying drone <NUM> to the protective cage <NUM>. Such a support <NUM> comprises support arms <NUM> or any suitable link adapted to join the attachment points of the ribs <NUM>, either directly or by means of a support connexion means <NUM>. The length of the support arm <NUM> may be tune so as to be easily adapted to the dimensions of the cage <NUM> at the selected attachment points. For example, they may be telescopic or comprise several segments which can be added to each other to determine their length. Depending of the needs, the support arms <NUM> may be flexible to be able to damp some choc in a vertical direction. For example, when landing or when elevating inside a closed space such as a warehouse, collisions from the floor or the top of a building may be damped thanks to the flexibility of the support arms <NUM>. Alternatively, the support arms <NUM> are reinforced so as to prevent any flexibility.

The support arms <NUM> originate from a support body <NUM>, normally at a central position. The support arms <NUM> may be rigidly fixed to the support body <NUM>. Alternatively, they can be articulated, for example by means of a hinge, so as to be able to rotate and adapt their relative angular position. The support body comprises a fixation mean <NUM> adapted to immobilise the drone <NUM>. Such a fixation means <NUM> may be universal and usable for any type of drones <NUM>. Alternatively, the fixation means <NUM> can be specific to some drones <NUM>. The fixation means <NUM> may be replaced by a different model, when necessary.

The support body <NUM> may be adapted to store some payload or to receive a pocket or bag which can be suspended on it.

The cage <NUM> here described may further comprise one or two caps <NUM>, which can be inserted in the rings 106a, 106b positioned at the extremities 141a, 141b of the ribs <NUM>. The cap <NUM> can comprise a head <NUM> and a cap body <NUM>, fixed to the head <NUM>. The cap body <NUM> may have a global cylindrical shape the dimensions of which are adapted to be inserted into the rings 106a, 106b positioned at the extremities 141a, 141b of the ribs <NUM>. The head has dimensions, in particular a diameter, larger than the cap body <NUM> and cannot pass through the rings 106a, 106b. The cap body is advantageously provided with flexible and elastic tabs <NUM> at its end opposite the head <NUM>. Alternatively or in addition, the cap body <NUM> may comprise flexible and elastic sections allowing to clip the cap <NUM> in the rings 106a, 106b. Thus, once the ribs <NUM> of the protective cage <NUM> are deployed, the cap <NUM> can be clipped at the extremities of the ribs <NUM>. In case, the extremities of the ribs <NUM> is provided with a releasable fixation such as a snap hook, a spring hook or any equivalent means, the cap body allows to secure the ribs <NUM> on the rings 106a, 106b by avoiding an accidental opening of such fast fixation means. In addition, the cap <NUM> may comprise indexing means allowing to maintain the ribs <NUM> at predetermined angular positions, once deployed. Such indexing means may be for example slots <NUM> provided in the cap body <NUM> and adapted to receive the thickness of the extremities 141a, 141b of the ribs <NUM>. The slots <NUM> are arranged as parallel indexing means, at predetermined angular positions on the cap body <NUM>. Alternatively or in addition, the head <NUM> may be provided with slots radially oriented and adapted to receive the thickness of the extremities 141a, 141b of the ribs <NUM> at predetermined angular positions. Such an arrangement may be used when the ribs <NUM> between the first rib and the last rib are free to move and slide along the strings <NUM>. In that case, their angular position can be determined with the caps <NUM> placed at each extremity. Even in case all the ribs have already a fixed angular position, the caps <NUM> reinforces the strength of the cage <NUM>.

The indexing means of the caps <NUM> further allow to lock the ribs <NUM> at predetermined angular positions, in addition to or in replacement of the closing part <NUM>. It is noted that the angular position of the indices of the cap <NUM> can be homogenous and regular. Alternatively, non-homogenous angular positions may be arranged, as above-mentioned. Depending on the needs, different caps <NUM>, having various angular distribution of the indices, can easily be used. It is here highlighted that the cap <NUM> is merely clipped on the cage <NUM> and that it does not need screwing step or additional locking or clamping steps. This provides an easy and fast means to maintain the ribs <NUM> at their relative angular position and/or lock the cage <NUM> at its deployed position.

The protective cage <NUM> of the present disclosure further comprises a closing part <NUM>. Such closing means allows to fil the space between the first and the last rib <NUM> once the cage <NUM> is deployed. It is here mentioned that the strings <NUM> joining and crossing the ribs <NUM> have a length corresponding to the circular distance along all the ribs <NUM> when the cage <NUM> is deployed, said distance depending on the position of the corresponding string along the ribs. The space remaining between the first and the last ribs <NUM> is thus not filed with the strings <NUM>. The closing part <NUM> comprises to this end one or several rods allowing to join the first and the last ribs <NUM>, so as to maintain them at the deployed position. Such rods have the adequate length, corresponding to their position along the ribs <NUM>. According to an embodiment, the closing part is fixed to one of the first and the last ribs <NUM> and can be removably connected to the other one of the first and the last ribs <NUM>. For example, the rod or the rods constituting the closing part <NUM> can be hinged on one of the first and last ribs <NUM>. The other extremity of the rod or rods of the closing part <NUM> may comprise a hook adapted to be latched on the other one of the first and last ribs <NUM>. Enough flexibility and elasticity may be required to provide tension of the strings <NUM>, once the cage is deployed and the closing part is closed. A mere pressure on the closing part <NUM> allows to lock the cage at its deployed stage.

According to another arrangement the rod or rods of the closing part <NUM> can be removed from both the first and the last ribs <NUM>. To this extend, they comprise a hook at both extremities which can be affixed to the first and the last ribs <NUM> to maintain the proper tension to the strings <NUM>.

The present disclosure also relates to a method of protecting a flying drone by means of the foldable protection cage <NUM> here described. The method comprises a step of deploying the ribs <NUM> around a virtual rotation axis passing by their extremities 141a, 141b so as to surround a drone <NUM>. Preferably, the step of deploying the ribs around the drone also allows, concomitantly, to position the drone and/or its support <NUM>, in the internal space defined by the ribs once deployed. A separate step of fixing the drone and/or its support <NUM> to the protective cage <NUM> can thus be avoided.

The method comprises a step of locking the cage <NUM> at its deployed position, by means of a closing part <NUM>. Such a closing part maintains at least the relative angular position of the first and last ribs <NUM>. Where applicable, the other ribs, between the first and the last one, may still be free to move.

The method may comprise a further step of clipping one or two caps <NUM> at the extremities 141a, 141b of the ribs, once deployed. It is highlighted that when the caps <NUM> comprise indexing means, allowing to maintain the ribs <NUM> at their relative angular position, this step may replace the above step of locking the cage at its deployed position by means of closing part <NUM>. Only one of the indexing cap and the closing part may thus be used. Preferably, both are used, further considering that no screwing or additional manipulations are required but just clipping the adequate cap and/or closing part.

The method may further comprise replacing one or several ribs <NUM>, independently of the other ones of the cage. This may be required after a collision to replace a damaged rib. This may also be advantageous for modulating the shape and size of the cage.

For all the disclosure, unless otherwise stated, the terms "vertical", "horizontal", and related terms, where employed, have the usual meaning, and correspond to the standard use of the described cage.

The terms "flying drone" denote any unmanned aerial vehicle, either running under autonomy or remotely piloted by a user. This is without limitation regarding the type and dimensions of the aerial vehicle, neither its use. It can be a surveillance vehicle, a vehicle dedicated to deliver payload, either indoor or outside, or any other vehicle.

Claim 1:
A protective cage (<NUM>) comprising
- a plurality of ribs (<NUM>) having an arcuate shape and two extremities (141a, 141b), each of the ribs being provided with a ring connection point at each extremity (141a, 141b), and comprising several string connexion points (111a, 111b, 111c, 111d, 111e) along their length,
- a first ring (106a) and a second ring (106b), each ring passing through the corresponding ring connexion points at each of said extremities, so that said ribs are combined together at their extremities by means of a corresponding ring, and allowing an angular shift between the ribs of said plurality of ribs from a folded position to a deployed position,
- at least one string (<NUM>) passing through said string connexion points (111a, 111b, 111c, 111d, 111e) of adjacent ribs from the first until the last rib of said plurality of ribs, wherein the length of said at least one string (<NUM>) corresponds to the maximal angular shift between the first and the last ribs (<NUM>),
- at least one locking means adapted to maintain the ribs at predetermined relative angular positions, once fully deployed, selected among:
- a cap (<NUM>) comprising a head (<NUM>) and a cap body (<NUM>) adapted to be removably inserted in said rings (106a, 106b) and
- a closing part (<NUM>) comprising one or more rods having at least one hook, adapted to removably and directly connect the first and the last ribs (<NUM>) at their maximal angular shift, while maintaining said at least one string (<NUM>) under tension.