BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The present disclosure relates to an unmanned aerial vehicle having a safety system comprising a parachute.

Description of the Related Technology

[0002] Unmanned aerial vehicles (UAVs), such as drones, are autonomous and/or remotely operated aerial vehicles. UAVs may be configured to fly using fixed wings or rotors and blades. There are a wide variety of faults that can occur during operation of a UAV. These include power loss, communication loss, mechanical breakage and circuit failure. In some cases, these faults can result in the unexpected descent of the UAV, such that it falls to the ground. Such an unexpected descent can pose a threat to the safety of humans who may be located below the descending UAV. UAVs may use parachutes to minimize the descent velocity during an unexpected descent; the parachute may be deployed manually or automatically, for example in response to a trigger.

[0003] Parachutes, and components required to deploy the parachute, can be bulky and heavy, and therefore significantly reduce the distance a UAV can fly on a single charge. Accordingly, there is a need for an improved parachute assembly which allows the UAV to fly more efficiently.

[0004] With UAV deliveries in urban areas set to become more commonplace, stringent safety systems are required to ensure the safety of humans in the event that these commercial UAVs malfunction and fall to the ground. Should the UAV experience a fault, a parachute may need to be deployed to reduce the likelihood of injury or damage. In some jurisdictions, safety regulations also require that UAVs which fly directly over people have a“black box” onboard. A black box, also known as a flight recorder, monitors, measures and records data associated with the UAV during flight. Data stored by the flight recorder can be used to better understand why the UAV experienced an unexpected descent, should such an event occur. For example, the flight recorder may record the particular fault which caused the UAV to fail. Existing UAVs may have a single circuit board which controls operation of the UAV as well as acting as a flight recorder. However, these circuit boards are easily damaged, meaning that any stored data becomes unusable. For example, the circuit boards may be damaged during a crash and/or by any components used to deploy the parachute. Accordingly, there is also a need for a UAV which provides protection to the flight recorder, to ensure it remains intact during an unexpected descent or crash. In particular, there is a need to protect the flight recorder from the forces generated when a parachute is deployed. By protecting the flight recorder, the data can be studied so that the safety of the UAV can be improved in future.

SUMMARY

[0005] According to a first aspect of the present disclosure, there is provided an unmanned aerial vehicle (UAV) comprising a plurality of rotors, wherein the UAV has a central axis about which the rotors are arranged. The UAV further comprises a parachute and a parachute deployment assembly. The parachute deployment assembly comprises one or more hollow members, each hollow member including a mass-storing section having an ejection axis, and one or more masses, where each mass is tethered to the parachute and is at least partially disposed within a mass-storing section of a corresponding hollow member. Each mass has a path of ejection defined by the ejection axis of the mass-storing section of the hollow member. The UAV further comprises a housing connected to the one or more hollow members to support the one or more hollow members. The parachute deployment assembly is configured to generate one or more forces to eject the one or more masses from the one or more hollow members to open the parachute. The housing is adapted to support the one or more hollow members, and may be configured with different respective ejection axes.

[0006] In one embodiment the respective ejection axes may be less than an angle of 45 degrees to a plane which is perpendicular to the central axis. The 45 degree angle between the ejection axes and a plane which is perpendicular to the central axis results in a UAV with a low profile, which makes the UAV more aerodynamic. A UAV with a low profile experiences relatively less drag during flight, and the battery which powers the flight of the UAV can be used more efficiently so that the UAV can fly further on a single charge. A low profile also reduces the likelihood of the UAV flight path being affected by strong winds. In addition, some UAVs may be stored on platforms/shelves, within a storage unit. A low profile allows more platforms and UAVs to be stored vertically within the same size unit.

[0007] As will be explained in more detail, the parachute deployment assembly has a plurality of hollow members and within each hollow member resides a mass (also known as a projectile or control mass). A force, generated by a pyrotechnic device for example, can cause the mass to be fired out of the hollow member in a direction dictated by the ejection axis defined by the hollow member. Each mass is tethered to the parachute; for example, the mass may be attached to the parachute at, or near to, the canopy of the parachute. Thus, as the masses are ejected in different directions, the parachute is opened quicker than it would in normal free-fall.

[0008] It will be understood that, as a consequence of the 45 degree angle between the ejection axes and a plane which is perpendicular to the central axis, the masses are initially ejected at an angle of less than 45 degrees with respect to the plane. It has been found that angles below 45 degrees results in a lower profile. Furthermore, angles below 45 degrees allow the canopy to be spread over a wide area in a short amount of time.

[0009] In the above example, the UAV comprises a plurality of rotors. A rotor may include a plurality of rotor blades, which are supported by a corresponding rotor arm. The rotor arms may extend away from a main body of the UAV. The parachute deployment assembly and housing may be connected to or integrated with the main body, for example. The main body may define the central axis of the UAV. A UAV located on the ground, or hovering in a stationary position, would have a vertical central axis which is perpendicular to a horizontal plane. During flight, the UAV may tilt with respect to the ground, such that the axis defined by the main body UAV is no longer vertical and the plane that is perpendicular to the central axis is no longer a horizontal plane.

[0010] In some examples, the rotor arms extend away from the main body of the UAV in a direction perpendicular to the central axis defined by the main body of the UAV. The rotor arms of the UAV may therefore he in the plane that is perpendicular to the axis defined by the main body of the UAV.

[0011] A UAV may comprise two or more rotors, each rotor having a plurality of rotor blades which rotate about an axis that is parallel to the axis defined by the main body of the UAV. Each rotor may be connected to a corresponding rotor arm. Preferably, the UAV comprises four rotors and four rotor arms. Each of the rotor arms extend away from the main body of the UAV and are therefore arranged around the central axis of the UAV. Accordingly, the rotors may also be said to be arranged around the central axis of the UAV.

[0012] The main body of the UAV may house electronic components, such as electronic circuitry and a power source. The main body may be located at the geometric centre of the UAV, and/or at the centre of mass of the UAV. In one example the main body comprises a payload container to temporarily house a payload during transportation by the UAV.

[0013] The one or more hollow members may be tubular. The masses inserted within the hollow members may be correspondingly shaped. For example, the hollow members may be cylindrical, and the masses may have a cylindrical portion which is received within the mass storing section of the hollow member. The hollow members may also be known as thrusters. The inner and/or outer diameter of the hollow members may decrease in size at increasing distances away from the housing.

[0014] A mass can be fully or partially inserted/received/disposed within a corresponding hollow member. The section of the hollow member which receives the mass may be known as a mass-storing section. Preferably, the mass is only partially disposed within a hollow member such that it protrudes out of one end of the hollow member. This can allow the mass to be tethered to the parachute, without requiring the parachute, or any tethers, to be received within the hollow member. This avoids tearing or otherwise damaging the parachute and ensures that the mass has a “snug” fit within the hollow member. A snug fit ensures the mass can be ejected most efficiently.

[0015] The housing of the UAV acts to support the one or more hollow members. The housing may be rigid so as to stably hold the one or more members in place as the parachute deployment assembly generates the forces to eject the masses from the hollow members. The shape of the housing therefore dictates the angle at which the hollow members are held.

[0016] There may be two or more hollow members. However, preferably there are three or four hollow members. It has been found that three or four hollow members allow the parachute to be inflated rapidly. In a specific example, the UAV comprises four rotors and four rotor arms and there are four hollow members. This arrangement provides a more stable UAV. The hollow members may be equally spaced around the housing.

[0017] The parachute deployment assembly may comprise one or more force generating devices, such as one or more pyrotechnic devices to generate the one or more forces to eject the masses. Other force generating devices may comprise compressed gas, springs, or black powder, etc. In some arrangements, each hollow member is associated with, or houses, a force generating device.

[0018] In certain examples, the housing is adapted to support the one or more hollow members with their respective ejection axes at less than 30 degrees to the plane. This arrangement provides an even lower profile, further increasing the aerodynamic profile of the UAV. Preferably, the housing is adapted to support the one or more hollow members with their respective ejection axes at less than 20 degrees to the plane. Still more preferably, the housing is adapted to support the one or more hollow members with their respective ejection axes at between about 10 degrees and about 20 degrees to the plane. It has been found that hollow members angled within this range, provide a good balance between (i) providing a very low profile, (ii) ensuring that the canopy of the parachute is spread as wide as possible in a short time period, and (iii) ensuring the masses and parachute do not collide with the rotors of the UAV. For example, if the hollow members are arranged below 10 degrees, the masses may collide with the rotor blades and/or the parachute may become entangled in the rotors. In a specific example, the housing is adapted to support the one or more hollow members with their respective ejection axes at about 15 degrees to the plane. In some examples, the housing is adapted to support the one or more hollow members with their respective ejection axes at greater than about 10 degrees above the plane. In some examples, the housing is adapted to support the one or more hollow members with their respective ejection axes at greater than about 10 degrees above the plane and less than about 45 degrees to the plane, such as greater than about 10 degrees and less than about 40 degrees, or greater than about 10 degrees and less than about 30 degrees, or greater than about 10 degrees and less than about 20 degrees, such as at about 15 degrees to the plane. In some examples, the angle at which the ejection axes are orientated is known as a predetermined angle.

[0019] In some examples, each of the hollow members are orientated at the same angle with respect to the plane, thereby providing a more aerodynamically symmetric and balanced UAV. In other examples, the hollow members are orientated at one or more different angles with respect to the plane. Orientating the hollow members at different angles can provide tailored/bespoke ejection paths for each mass, which may be useful to ensure that the ejected masses avoid certain instruments and/or rotors located on the UAV, or that the masses spread the canopy of the parachute in a particular way.

[0020] In some arrangements, the UAV comprises a parachute cover, and the parachute is stored between the housing and the parachute cover. The parachute may be folded or otherwise packed at least partially between the housing and the parachute cover. For example, the parachute may rest on top of the housing and/or the hollow members and be contained by the cover which extends over the hollow members and housing. The cover protects the parachute, hollow members, housing and other components from wind, rain and other types of weather. By being stored between the housing and cover, the parachute is positioned so that it can more easily inflate and open as the masses are ejected. The cover may be dome shaped, to provide a more aerodynamic profile. When the hollow members are arranged at an angle below 45 degrees, the height of the cover can be reduced, for a fixed length hollow member. In some arrangements, the UAV comprises a parachute base which extends below the housing and hollow members. The parachute base may be connected to the parachute cover to fully enclose the parachute, housing and parachute deployment assembly. In some examples, the parachute cover may be known as a top cover and the parachute base may be known as a bottom cover. [0021] The parachute cover may be connected to the one or more masses. For example, the parachute cover may be indirectly or directly connected to the one or more masses. The cover may further be configured to be opened by the one or more masses as they are ejected from the one or more hollow members. This allows the cover to be opened automatically at the same time the parachute is deployed, without requiring separate components to open the cover. This reduces the time taken to deploy the parachute, and reduces the complexity of the parachute deployment assembly.

[0022] In some examples, the parachute cover is configured to detach from the UAV as the one or more masses are ejected from the one or more hollow members. The parachute cover may therefore be a removable cover that is separated from the UAV as the parachute is deployed. This configuration can avoid the parachute from becoming tangled with the parachute cover. It can also reduce the weight of the UAV, which can allow the UAV to decelerate faster.

[0023] The parachute cover may be made of a lightweight material, such as plastic. The detached parachute may therefore float/glide to the ground without injuring people below.

[0024] In other examples, the parachute cover remains attached to the UAV after it has been opened, so that it can be reused. This may also be useful to improve safety, if the cover is heavy.

[0025] In some arrangements, the parachute cover is connected to the one or more masses via one or more shear pins, and wherein the one or more shear pins are configured to break as the one or more masses are ejected. The parachute cover is therefore indirectly connected to the one or more masses. A shear pin is a screw, bolt, or fastener which is arranged to shear/break once a predetermined force is applied to the shear pin. The one or more shear pins are arranged to connect the parachute cover to the UAV. For example, they may each extend through a corresponding through hole formed in the parachute cover. Each shear pin may be arranged to abut a corresponding mass such that as the mass is ejected from the hollow member, it applies a force to the shear pin which causes it to break or snap. Doing so releases the cover, allowing it to open. A shear pin provides a simple but effective mechanism for opening the parachute cover, without the need for complex and precise electronics used to open the cover. The use of shear pins therefore simplifies operation.

[0026] The one or more masses may be shaped to conform to an outer surface of a corresponding shear pin. This provides a good abutment between the mass and shear pin, and increases the likelihood of the shear pin breaking. In a first example, the masses may have a concave outer portion which receive a cylindrical or curved portion of the shear pin. The masses may have a U-shaped section at one end to receive the shear pin. In a second example, the masses may have an aperture or hole, and the shear pin may extend through the aperture/hole. An aperture/hole may provide a more secure arrangement to reduce the likelihood of misalignment.

[0027] In a particular arrangement, the UAV comprises four rotors angularly spaced by substantially 90 degrees with respect to each other about the central axis, and the parachute deployment assembly comprises four hollow members each arranged at substantially 45 degrees with respect to the rotors about the central axis. Each hollow member therefore extends outwards from the main body of the UAV between each of the rotors and rotor arms. Thus, as the masses are ejected, they project away from the UAV in a direction that is less likely to cause the parachute to be tangled in the rotors. This allows the ejection axes of the hollow members to be arranged at 45 degrees or lower, with respect to the plane. Thus, this particular arrangement enables a lower profile. In other examples, there may be a different number of rotors spaced around the central axis. Each hollow member may be arranged between a rotor. For example, each hollow member may be arranged at a midpoint between each rotor. In a particular example, the number of hollow members corresponds to the number of rotors. This arrangement can provide a more balanced UAV.

[0028] In some examples, the one or more hollow members are substantially straight along their length. Straight hollow members can provide a more energy efficient arrangement. For example, a force generating device may generate a force by causing a gas to rapidly expand through the hollow member. A straight hollow member can allow the gas (and therefore energy) to pass through with less resistance when compared to a bent or curved hollow member. A stronger force may allow the parachute to be inflated quicker.

[0029] In some embodiments, the UAV comprises an electronic module configured to measure or record flight data associated with the UAV, and the housing defines an enclosure to at least partially contain and support the electronic module within the enclosure. The housing is therefore arranged to protect the electronic module from the forces generated by the parachute deployment assembly. The electronic module can act as a flight recorder by measuring and/or recording data associated with the UAV during operation. The electronic module can also cause the parachute deployment assembly to eject the one or more masses to deploy the parachute.

[0030] The electronic module, acting as a flight recorder, may record data associated with any faults which cause the UAV to descend unexpectedly. The housing of the UAV defines an enclosure to contain and support the electronic module. The housing therefore provides protection to the electronic module, to ensure it remains intact when the parachute deployment assembly generates one or more forces to eject the one or more masses. The housing is connected to the hollow members, so absorbs forces generated within the hollow members. The housing can also provide protection from the forces generated as the UAV abruptly decelerates when the parachute fully inflates, as well as impact forces generated as the UAV lands on the ground. By protecting the integrity of the electronic module, the safety of future UAV flights can be improved by analysis of the data stored thereon.

[0031] In some arrangements, the housing is a single part which encloses the electronic module. In other arrangements, the housing may comprise two or more parts which are connected to each other.

[0032] The electronic module may be a printed circuit board (PCB). The UAV may comprise a second electronic module to control flight of the UAV. The electronic module may therefore be separate to, and independent from, the second electronic module. The electronic module may be powered by a power source that is separate to, and independent from a power source used to power the rotors of the UAV.

[0033] In some examples, the housing and electronic module each delimit an aperture through which a suspension line of the parachute is routed to connect the parachute to a main body of the UAV. The suspension line may sometimes be known as a riser. Thus, in some examples, the parachute is connected to the main body of the UAV rather than being connected to the parachute deployment assembly itself. This allows the parachute to be more securely attached to the UAV, and reduces the likelihood of damaging the electronic module when the parachute fully opens and the UAV rapidly decelerates. This also means that the housing, and therefore the electronic module and parachute deployment assembly can be attached to the main body of the UAV without requiring the attachment means to be secure enough to withstand the tension in the suspension line. This allows the attachment means to be smaller and lighter, and again helps protect the electronic module. In some examples, the attachment assemblies which connect the housing to the UAV may break as the parachute is opened. The aperture through the housing and electronic module allows these to break, while the housing and electronic module remain connected to the UAV via the suspension line. For example, the housing may detach from the main body of the UAV and move up the suspension line without falling to the ground.

[0034] The housing may comprise an upper part, extending above and at least partially covering an upper surface of the electronic module, and a lower part arranged between a lower surface of the electronic module and a main body of the UAV. The housing therefore protects upper and lower surfaces of the electronic module and provides a protective shell around the electronic module. This arrangement also enables easy assembly; the upper and lower parts can be made separately and then be connected together to surround the electronic module. The lower part may at least partially cover the lower surface of the electronic module. The lower and upper part may each delimit an aperture to receive the suspension line.

[0035] The upper part may delimit one or more apertures, where each aperture receives a hollow member. A wire can connect a force generating device (located in the hollow member) to the electronic module via the aperture formed in the upper part.

[0036] In some examples, the lower part comprises at least one protrusion configured to abut a surface of the upper part. The one or more protrusions help distribute the energy from the upper part to the lower part as one or more forces are applied to the upper part. In some examples, there may be at least two protrusions, and the protrusions may limit relative lateral movement between the upper and lower parts. The presence of two protrusions can help stop or reduce lateral movement in one dimension, such as forward and back or side to side. In one arrangement, the lower part comprises four protrusions. Four protrusions help stop lateral movement in two dimensions, such as forward and back and side to side. In another arrangement, the lower part comprises three protrusions spaced apart by about 120 degrees, which can also stop lateral movement in two dimensions. Each protrusion may abut an inner surface of the upper part.

[0037] The housing may comprise one or more attachment assemblies for attaching the housing to the UAV. This allows the housing, and therefore the electronic module and hollow members to be disconnected from the UAV. This is useful because the electronic module and hollow members can be serviced and prepared separately from the UAV and be connected when necessary. This is particularly advantageous where pyrotechnic devices, or other force generating devices are used. For safety reasons, it is desirable to keep these components isolated. By having a“modular” parachute deployment assembly (that is separate from the UAV), safety can be improved because the parachute deployment assembly can be stored separately from the UAV when the UAV is being serviced or prepared for flight. Storing separately can reduce the likelihood of accidentally triggering deployment of the parachute, which can injure people who may be handling the UAV.

[0038] In one arrangement, the one or more attachment assemblies each comprise a through hole to receive a fastener, such as a bolt/screw/rivet. This type of attachment assembly is simple, effective, lightweight and cheap.

[0039] In a particular arrangement, the upper part comprises a first through hole, the lower part comprises a second through hole, and a fastener extends through the first and second through holes, thereby to attach the housing the UAV. Thus, the same through holes allow the two parts to be connected together, while also allowing the housing to be connected to the UAV. The holes therefore have a dual purpose, which this reduces the number of components needed, therefore reducing the weight of the UAV. A fastener may be a bolt or screw, for example. The fastener may also extend into a receiving hole formed on the main body of the UAV.

[0040] The housing may be rigid, to protect the electronic module from the forces generated to eject the masses from the hollow members. The rigid structure absorbs impact forces and distributes these around the electronic module, thereby protecting the electronic module.

[0041] The housing may be made from a composite material. In one example, the housing comprises carbon fibre. Carbon fibre is a particularly suitable material for the housing because it has high stiffness, high tensile strength, and low weight. In one example, an Aramid fibre (such as Kevlar) may also be added to increase toughness/durability.

[0042] The housing may also comprise reinforcing ribs. The use of ribs helps provide strength to the housing, while allowing other parts of the housing to have a relatively thin wall thickness. This allows less material to be used, while providing the same or greater protection. The ribs may also be known as elongated protrusions/ridges. In one arrangement, the ribs are located on the upper part of the housing. The ribs may generally extend in the same direction as an ejection axis defined by a corresponding hollow member. This helps prevent the housing from deforming as the mass is ejected from the hollow member. There may be at least one reinforcing rib associated with each hollow member.

[0043] The UAV (or the parachute assembly) may further comprise one or more attachment assemblies for attaching the electronic module to the housing. This allows the electronic module to be supported within the enclosure to limit movement of the electronic module within the enclosure.

[0044] Unlike the housing, the attachment assembly may permit some movement. For example, the attachment assembly may act as a vibration dampener, allowing the electronic module to absorb any residual forces which reach the electronic module. In one particular example, the attachment assembly comprises (i) a fastener extending through a first through hole formed in the housing and a second through hole formed in the electronic module and (ii) at least one resilient member connected to the fastener to absorb vibrational forces. The fastener therefore connects the electronic module to the housing and the resilient member allows the electronic module to move relative to the housing, thereby to absorb any vibrational forces. In this way the attachment assembly performs two functions. A resilient member may be arranged between the electronic module and an inner surface of the housing (such as an inner surface of the upper or lower parts of the housing). Additionally, or alternatively, a resilient member may be arranged outside of the housing, between an outer surface of the housing and an end of the fastener. For example, the fastener may be a bolt or screw, and the resilient member may be arranged between an outer surface of the housing and the head of the bolt/screw. In one example, the fastener extends through the first through hole formed in the housing, through the second through hole formed in the electronic module, and through a third through hole formed in the housing. The fastener can therefore extend all the way through the housing. This may allow the electronic module to be held more securely. The first through hole may be formed in the upper part of the housing, and the third through hole may be formed in the lower part of the housing.

[0045] In some arrangements, the electronic module comprises one or more sensors to measure data during flight. By absorbing vibrational forces, the reliability of the data can be improved. For example, movement of the electronic module may introduce errors into the measured data.

[0046] In some arrangements, the UAV (or parachute assembly) comprises a resilient member disposed between the electronic module and the housing. The resilient member can absorb any vibrational forces during flight and the forces generated by parachute deployment assembly.

[0047] A resilient member may be a spring (for example, the electronic module may be suspended by a spring), or it could be foam or rubber.

[0048] The electronic module may be square or rectangular in shape and comprise four sides and four comers, wherein the housing covers a portion of each of the four sides. For example, the housing may cover only a portion of each of the four sides, without covering at least one of the four comers. This arrangement is a balance between protecting the electronic module and making the housing more lightweight, by using less material.

[0049] As mentioned, in some examples, the parachute deployment assembly further comprises one or more pyrotechnic devices configured to generate the one or more forces to eject the one or more masses from the one or more hollow members, wherein each pyrotechnic device is at least partially disposed within a corresponding hollow member. The parachute deployment assembly may further comprise one or more wires extending between each pyrotechnic device and the electronic module, wherein the one or more wires are arranged between a surface of the electronic module and the housing. This allows the wires to be protected by the housing. This can avoid accidentally triggering the pyrotechnics. For example, the wires are less likely to be exposed to electrostatic charges, which can inadvertently cause the pyrotechnic device to trigger. The pyrotechnic device may be at least partially disposed within a section of the hollow member.

[0050] In an alternate example of the first aspect, the housing is adapted to support the one or more hollow members with their respective ejection axes at less than 80 degrees to the plane. While such an example UAV may have a higher profile than other examples described above, the UAV may incorporate one or more of the other features described above to provide alternative advantages. In other examples, the predetermined angle may be less than about 70 degrees, or less than about 60 degrees, or less than about 50 degrees, or less than about 45 degrees, or less than about 40 degrees, or less than about 30 degrees, or less than about 20 degrees, such as about 15 degrees. In some examples, the predetermined angle is between about 10 degrees and about 80 degrees. For example, the predetermined angle may be between about 10 degrees and about 70 degrees, or between about 10 degrees and about 60 degrees, or between about 10 degrees and about 50 degrees, or between about 10 degrees and about 45 degrees, or between about 10 degrees and about 40 degrees, or between about 10 degrees and about 30 degrees, or between about 10 degrees and about 20 degrees, such as about 15 degrees.

[0051] According to a second aspect of the present disclosure, there is provided a parachute assembly for a UAV. The parachute assembly comprises a parachute and a parachute deployment assembly. The parachute deployment assembly comprises one or more hollow members, and one or more masses, each mass being tethered to the parachute and being at least partially disposed within a corresponding hollow member. The parachute deployment assembly is configured to generate one or more forces to eject the one or more masses from the one or more hollow members to open the parachute. The parachute assembly further comprises an electronic module, configured to: (i) measure or record flight data associated with the UAV, and (ii) cause the parachute deployment assembly to eject the one or more masses to deploy the parachute. The parachute assembly further comprises a housing connected to the one or more hollow members to support the one or more hollow members. The housing also defines an enclosure to at least partially contain and support the electronic module within the enclosure, and generally to protect the electronic module from the forces generated by the parachute deployment assembly.

[0052] The electronic module may cause the parachute to be deployed in response to detecting a fault with the UAV. The fault may be determined from the flight data associated with the UAV. The electronic module may therefore comprise one or more sensors to measure flight data. The electronic module may alternatively cause the parachute to be deployed in response to a manual command received by the UAV. [0053] As mentioned, the electronic module, acting as a flight recorder, may record data associated with any faults which cause the UAV to descend unexpectedly. The housing of the UAV defines an enclosure to contain and support the electronic module. The housing therefore provides protection to the electronic module, to ensure it remains intact when the parachute deployment assembly generates one or more forces to eject the one or more masses. The housing is connected to the hollow members, so absorbs forces generated within the hollow members. The housing can also provide protection from the forces generated as the UAV abruptly decelerates when the parachute fully inflates, as well as impact forces generated as the UAV lands on the ground. As previously mentioned, by protecting the integrity of the electronic module, flight data has a higher chance of being preserved, meaning that the safety of future UAV flights can be improved by analysis of the flight data.

[0054] In the above examples, the housing contains and supports the electronic module. The electronic module and housing are therefore adjoined/connected. This means that the electronic module is arranged in close proximity to the hollow members. This is advantageous because the physical distance between each of the hollow members and the electronic module is reduced, so that the parachute deployment assembly can quickly receive signals/data from the nearby electronic module to cause the parachute to deploy. This therefore reduces the time taken to deploy the parachute. As mentioned above, wires may extend between the electronic module and force generating devices located within each of the hollow members. Each force generating device receives a signal from electronic module and generates a force to eject the mass. The signal may be known as an All-Fire Current.

[0055] In some examples, two or more hollow members extend away from the housing and electronic module, and are spaced equally around the housing and electronic module. The electronic module and housing may therefore be located centrally within the parachute deployment assembly. This arrangement minimizes the physical distance between the electronic module and each of the hollow members. Accordingly, any wires extending between the electronic module and respective force generating devices can be of equal length. All other factors being substantially equal this increases the chance of the force generating devices receiving signals in synchrony, so that the masses are ejected in synchrony. When the masses are ejected at substantially the same time, the parachute inflates more effectively, reliably and rapidly. Furthermore, by minimizing the physical distance between the electronic module and each of the hollow members, any wires extending between the electronic module and force generating device can be made shorter. A shorter wire is lighter. Furthermore, shorter wires ensure that the All-Fire Current signal sent to the force generating devices has the required power level. A long wire would mean that the signal has a power level that is too low to trigger deployment of the parachute. In a specific example, the force generating devices are pyrotechnic devices.

[0056] In some examples, the electronic module may be configured to do only one of “measure or record flight data associated with the UAV” and“cause the parachute deployment assembly to eject the one or more masses to deploy the parachute”.

[0057] The parachute assembly may be integrated with, or be connected to, a UAV. As mentioned, this allows the housing, and therefore the electronic module and hollow members to be disconnected from the UAV.

[0058] Each of the one or more hollow members may have a mass-storing section defining an ejection axis. Each of the one or more masses may be at least partially disposed within a mass storing section of a corresponding hollow member and have a path of ejection defined by the ejection axis of the mass-storing section of the hollow member.

[0059] Features described in relation to the first aspect may also be incorporated in the second aspect. Similarly, features described in the second aspect may be incorporated in the first aspect.

[0060] According to a third aspect of the present disclosure, there is provided a parachute assembly for a UAV. The parachute assembly comprises an electronic module configured to measure or record flight data associated with the UAV, and trigger deployment of a parachute. The parachute assembly further comprises a housing configured to support the electronic module, and the housing and electronic module each delimit an aperture through which a suspension line of the parachute is routed to connect the parachute to a main body of the UAV. Thus, as mentioned above, this allows the parachute to be more securely attached to the UAV, and reduces the likelihood of damaging the electronic module when the parachute fully opens and the UAV rapidly decelerates. This arrangement also means that the housing, and therefore the electronic module and parachute deployment assembly can be attached to the main body of the UAV without requiring the attachment means to be secure enough to withstand the tension in the suspension line. This allows the attachment means to be smaller and lighter, and again helps protect the electronic module.

[0061] Features described in relation to the first and second aspects may also be incorporated in the third aspect.

[0062] According to a fourth aspect of the present disclosure, there is provided an unmanned aerial vehicle (UAV) comprising a plurality of rotors, wherein the UAV has a central axis about which the rotors are arranged. The UAV further comprises a parachute and a parachute deployment assembly. The parachute deployment assembly comprises one or more hollow members, each hollow member including a mass-storing section having an ejection axis, and one or more masses, where each mass is tethered to the parachute and is at least partially disposed within a mass-storing section of a corresponding hollow member. Each mass has a path of ejection defined by the ejection axis of the mass-storing section of the hollow member. The UAV further comprises a housing connected to the one or more hollow members to support the one or more hollow members. The parachute deployment assembly is configured to generate one or more forces to eject the one or more masses from the one or more hollow members to open the parachute. The housing is adapted to support the one or more hollow members with their respective ejection axes at a predetermined angle with respect to a plane that is perpendicular to the central axis.

[0063] In some examples, the predetermined angle is less than about 80 degrees. For example, the housing is adapted to support the one or more hollow members with their respective ejection axes at less than 80 degrees to the plane. In other examples, the predetermined angle may be less than about 70 degrees, or less than about 60 degrees, or less than about 50 degrees, or less than about 45 degrees, or less than about 40 degrees, or less than about 30 degrees, or less than about 20 degrees, such as about 15 degrees. In some examples, the predetermined angle is between about 10 degrees and about 80 degrees. For example, the predetermined angle may be between about 10 degrees and about 70 degrees, or between about 10 degrees and about 60 degrees, or between about 10 degrees and about 50 degrees, or between about 10 degrees and about 45 degrees, or between about 10 degrees and about 40 degrees, or between about 10 degrees and about 30 degrees, or between about 10 degrees and about 20 degrees, such as about 15 degrees.

[0064] Features described in relation to the first, second and third aspects may also be incorporated in the third aspect. Similarly, features described in relation to the fourth aspect may also be incorporated into the first, second or third aspects.

[0065] Further features and advantages of the disclosure will become apparent from the following description of preferred embodiments of the disclosure, given by way of example only, which is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a side view of an unmanned aerial vehicle in accordance with an example; [0067] Figure 2 is a top view of a parachute deployment assembly in accordance with an example;

[0068] Figure 3 is a bottom view of a parachute deployment assembly in accordance with an example;

[0069] Figure 4 is a plan view of a parachute deployment assembly in accordance with an example;

[0070] Figure 5 is a perspective view of a parachute cover in accordance with an example;

[0071] Figures 6-9 are plan views of a parachute being deployed from the unmanned aerial vehicle of Figure 1;

[0072] Figure 10 is a side view of the parachute cover, base and a hollow member at a first time;

[0073] Figure 11 is a side view of the parachute cover, base and a hollow member at a second, later time;

[0074] Figure 12 is a side view of a hollow member;

[0075] Figure 13 is a perspective view of a top part of the housing;

[0076] Figure 14 is a perspective view of a bottom part of the housing;

[0077] Figure 15 is a side view of the housing and electronic module in accordance with a first example;

[0078] Figure 16 is a side view of the housing and electronic module in accordance with a second example;

[0079] Figure 17 is a side view of the unmanned aerial vehicle and a deployed parachute at a first time; and

[0080] Figure 18 is a side view of the unmanned aerial vehicle and a deployed parachute at a second, later time.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

[0081] Figure 1 is a side view of a UAV, or drone, according to an example. The UAV 100 comprises a main body 102 and a plurality of rotor arms 104 which extend outwards and away from the body 102. The UAV 100 comprises four rotor arms 104 in this example, each supporting a rotor 106 towards one end. The UAV 100 may therefore be referred to as a“quadcopter”. In other examples, the UAV 100 may comprise two, three, five or more rotor arms 104 and a corresponding number of rotors 106. The rotors 106 are mounted towards distal ends of the rotor arms 104, however they may be mounted at any location along the length of the rotor arms 104. Each rotor 106 may comprise a plurality of rotor blades 108 which rotate about a rotation axis. The rotors 106 may also comprise a motor which generates rotational motion to cause the plurality of rotor blades 108 to rotate and generate lift. By controlling the rotational velocity of the rotor blades 108 associated with each rotor 106, the UAV 100 can be configured to hover, or fly in a particular direction.

[0082] The main body 102 of the UAV defines a central axis 110. In the configuration shown, the UAV is shown hovering above the ground 112, such that the central axis 110 is vertically orientated. In this hovering configuration, the ground 112 defines a horizontal plane that is perpendicular to the central axis 110. While the rotor arms 104 are illustrated as being perpendicular to the central axis 110, the rotor arms 104 may be angled with respect to the central axis 110 in some examples. The rotation axes of the rotors are parallel to the central axis 110.

[0083] Connected to the top of the main body 102 is a parachute deployment assembly (not shown). In Figure 1, the parachute deployment assembly is covered by a parachute cover 114. The parachute cover 114 also conceals a parachute. The parachute deployment assembly comprises components which enable the parachute to be deployed from the stowed configuration of Figure 1. The parachute can be deployed to avoid injuring or damaging people or buildings below the UAV 100 should an unexpended descent occur.

[0084] Figure 2 shows the parachute deployment assembly in isolation of the UAV 100. The parachute deployment assembly of this example comprises four hollow members 122. Each hollow member 122 is configured to receive a corresponding mass (not shown in Figure 2) which is at least partially inserted into the hollow member 122. In other examples there may be two, three or more hollow members 122.

[0085] Figure 3 shows an under-side of an example parachute deployment assembly. In this example, a mass 124 is shown arranged within each hollow member 122. The section of the hollow member 122 which receives the mass 124 may be known as a mass-storing section. The masses 124 may be known as control masses or projectiles, and are ejected from the hollow members 122 by a force generated within the hollow member 122. Each mass 124 is tethered to the parachute, so that the parachute is opened and spread wide as the masses 124 travel away from the UAV 100 in different directions. The parachute deployment assembly therefore rapidly causes the parachute to open, when needed.

[0086] In one example, pyrotechnic devices are arranged within each hollow member 122. Each pyrotechnic device, when triggered, generates a force to push the mass 124 out of the hollow member 122 along a path of ejection defined by the hollow member 122. The path of ejection is the path followed by the mass 124 as it travels away from the UAV 100.

[0087] Figures 2 and 3 also depict a housing 126. The housing 126 may be a single entity, or may comprise multiple parts joined together. In the example shown, the housing 126 comprises an upper part 128 (shown in most clearly in Figure 2) and a lower part 130 (shown most clearly in Figure 3). Each hollow member 122 is connected to the housing 126 at one end, and the housing 126 therefore supports the hollow members 122 to hold them at a predetermined angle with respect to a plane which is perpendicular to the central axis 110 of the UAV.

[0088] Figures 2 and 3 also depict an electronic module 132. In Figure 2, the electronic module 132 comprises two circuit board layers which are connected together, and in Figure 3 the electronic module 132 comprises a single circuit board layer. The electronic module 132 may take any form. In either case, the electronic module 132 is configured to act as a flight recorder, and therefore measures or records flight data associated with the UAV 100. The electronic module 132 may also perform other functions, such as causing the parachute deployment assembly to eject the masses 124 so that the parachute is deployed. This is generally referred to as an Autonomous Triggering System (ATS). Further functions may include operating as a Flight Termination System (by causing the rotors to terminate if the UAV is traveling off course) or operating as an independent power supply.

[0089] The housing 126 defines an enclosure to at least partially contain and support the electronic module 132 within the enclosure. The forces generated by the parachute deployment assembly could damage the electronic module 132 if it were not protected. The housing 126 therefore protects the electronic module 132 by forming a rigid shell around the electronic module 132. It is desirable to keep the electronic module 132 in close proximity to the hollow members 122 to ensure that the All-Fire Current signal sent to the force generating devices has the required power level. A long wire would mean that the signal has a power level that is too low to trigger deployment of the parachute.

[0090] In a particular example, the electronic module 132 comprises one or more sensors, such as an accelerometer, a magnetometer, GPS sensor, an altimeter, a barometer, and/or a gyroscope. The electronic module 132 may also comprise a controller, such as a processor, to analyse the data from the one or more sensors. Based on this data, decisions may be taken. For example, the controller may cause the parachute deployment assembly to eject the one or more masses to deploy the parachute if a fault or error is detected. A fault or error may be detected if the one or more sensors indicate that (i) the UAV has tilted beyond a first threshold, (ii) there is loss of power to the rotors or (iii) the descent speed of the UAV exceeds a second threshold. Other criteria may also indicate when a fault has occurred. The cause of the fault (or the associated data which led to the fault being detected) may be stored in memory for later analysis. The electronic module 132 may therefore also comprise memory to store data associated with any or all of the sensors. The memory may also store log data associated with the flight and other operations of the UAV. The log data may include information associated with any faults or errors detected by the UAV. Data stored in memory can be reviewed by an engineer to assess the state of the UAV before it failed and began an unexpected descent. The electronic module 132 can therefore act as a flight recorder by recording data associated with the UAV. It is therefore important to protect the electronic module.

[0091] Figure 4 is a diagrammatic representation of the parachute deployment assembly shown in Figures 2 and 3.

[0092] Figure 5 depicts the parachute cover 114 which extends over the parachute deployment assembly. The cover 114 also covers the parachute 134, which is seen folded/draped over the housing 126 and the hollow members 122. In this example, the cover 114 is transparent, such that the parachute 134 and hollow members 122 can be seen beneath the cover 113. The parachute cover 114 may be made from plastic, and is preferably thin, flexible and lightweight. Figure 5 also depicts a parachute base 136 which extends at least partially under the housing 126. The parachute 114 therefore resides between the base 136 and cover 144. The base 136 helps contain the parachute 134, and provide a more aerodynamic profile. The housing 126 may be connected to the UAV 100 through the base 136. For example, a screw or bolt may extend through the housing 126 and base 136.

[0093] Figure 5 also shows a number of shear pins 138 which extend through the cover 114 and into the base 136. Since the base 136 is connected to the UAV 100, the cover is anchored in place via the shear pins 138. Each shear pin 138 takes the form of a bolt, where the head of the shear pin 138 is arranged on the outside of the cover 114 and the nut of the shear pin 138 is arranged on the outside of the base 136. A washer 140 may be arranged between the head of the shear pin 138 and the cover 114.

[0094] The shear pin 138 of this example is made from plastic, and is designed to break/snap when a mass 124 applies a threshold force to the shear pin 138 as it is being ejected from the hollow member 122. In the stowed configuration shown in Figure 5, the mass 124 protrudes from the hollow member 122 and abuts the shear pin 138 at a point along its length. When the four masses 124 are ejected, the four shear pins 138 break, the cover 114 becomes loose and separates from the UAV 100 as the parachute 134 opens. The opening parachute 134, external airflow, and any high velocity airflow from within the hollow members 122 can all help detach the cover 114 from the UAV 100.

[0095] Figures 6-9 are diagrammatic representations of various steps during parachute deployment. Figure 6 depicts a plan view of the UAV 100 before the parachute 134 has been deployed. Figure 6 shows the parachute deployment assembly arranged beneath the cover 114. The parachute 134 is shown arranged under the cover 114, and draped over the parachute deployment assembly. Four rotor arms 104 extend away from the main body 102 of the UAV 100, and are separated by about 90 degrees around the central axis 110 of the UAV. The rotors 106 are arranged at the distal ends of the rotor arms 104. The four rotors 106 are spaced by about 90 degrees with respect to each other about the central axis 110. The central axis 110 extends into the page, through the center of the main body 102.

[0096] In the example shown in Figure 6 the four hollow members 122 are each arranged at 45 degrees with respect to the rotors 106 about the central axis 110. For example, each hollow member 122 defines an axis 142, such as an ejection axis, and each rotor arm 104 defines an axis 144, where an angle 146 of 45 degrees is subtended between the axes 142, 144. The hollow members 122 are therefore separated by about 90 degrees around the central axis 110 of the UAV. This arrangement means that the path of ejection for each mass 126 avoids the rotor blades 108.

[0097] Figure 7 depicts the UAV 100 at a point later in time than that depicted in Figure 6. In Figure 7, the parachute 134 has been deployed, but is not yet fully open. In this particular example, the electronic module 132 detected a fault with the UAV 100 and caused the parachute deployment assembly to eject the masses 124 from the hollow members 122. For example, the electronic module 132 sent a command to each of the four pyrotechnic devices located within the hollow members 122 to cause them to trigger and generate a force to eject the masses 124.

[0098] As the masses 124 are ejected, the shear pins 138 break, and the cover 114 detaches from the UAV 100. Figure 7 shows the cover 114 separated from the UAV 100 as the parachute is opened.

[0099] Figure 7 depicts the masses 124 at a certain distance from the UAV 100 having followed a path of ejection 148 at least partially dictated by the hollow members 122. The weight of the masses 124 and any wind resistance will also affect the path of ejection 148. The path of ejection 148 may be parabolic when viewed in side elevation, for example. Due the to the arrangement of the hollow members 122, the masses 124 follow a path between adjacent rotors. Each mass 124 is tethered to the parachute 134, and therefore draws the parachute 134 with it as it moves away from the UAV 100.

[0100] Figure 8 depicts the UAV 100 at a point later in time than that depicted in Figure

7. In Figure 8, the parachute 134 has begun to inflate, but is not yet fully open. The masses 124 are about to reach their maximum distance from the UAV 100. At the point of maximum distance, the masses 124 may come to a complete stop as the parachute 134 is drawn taught. Figure 8 shows the UAV 100 having descended in height, into the page, and the parachute cover 114 has begun to drift away from the UAV 100 and free fall to the ground. Due to the parachute cover 114 being lightweight and/or dome-shaped, the parachute cover 114 descends at a rate that is slower than that of the UAV.

[0101] Figure 9 depicts the UAV 100 at a point later in time than that depicted in Figure

8. In Figure 9, the parachute 134 is fully open. The masses 124 are obscured from view, and hang below the canopy of the parachute 134. In Figure 9, the parachute cover 114 has drifted away from the UAV 100 and out of view. The UAV 100 will continue to descent towards the ground, and land safely.

[0102] Figure 10 depicts a side view of the parachute deployment assembly at a time corresponding to that shown in Figure 6. Figure 10 shows a shear pin 138 extending through ahole formed in the parachute cover 114 and into the base 136. The mass 124 is positioned in abutment with the shear pin 138, and is partially disposed within the hollow member 122. The parachute 134 is tethered to the mass 124 and is folded or otherwise arranged between the base 136 and cover 114.

[0103] Figure 11 depicts a side view of the parachute deployment assembly at a time corresponding to that shown in Figure 7. Figure 11 shows the mass 124 following a path of ejection 148 having been ejected from the hollow member 122. The mass 124 was forced against the shear pin 138, causing it to snap into two portions 138a, 138b. As the mass 124 travels away from the hollow member 122, the mass pulls the parachute 134 with it. Figure 11 shows the mass being tethered to the parachute via a loop 134b. The loop 134b, in this example, passes through a through hole formed in the mass 124. The snapping/breaking of the shear pin 138 causes the cover 114 to come loose and open.

[0104] Figure 12 depicts a cross-sectional side-view of the housing 126, the hollow member 122 and the electronic module 132. As mentioned, preferably the one or more hollow members 122 are angled at less than about 45 degrees to a plane 150 which is perpendicular to the central axis 110 of the UAV 100. In Figure 12, the plane 150 extends into the page. The hollow member 122 defines an ejection axis 152 and an angle 154 is subtended between the ejection axis 152 and the plane 150. The ejection axis 152 may be the longitudinal axis of the hollow member, for example. In this particular example, the angle 154 subtended between the ejection axis 152 and the plane 150 is 15 degrees. In other examples, the angle 154 may be between about 10 degrees and about 80 degrees. When the plane 150 is orientated horizontally, the angle 154 may be known as an elevation angle. The path of ejection 148 extends from the ejection axis at the end 122a of the hollow member 122.

[0105] In the example shown, the hollow member 122 is straight along its length. In other examples, the hollow member 122 may be bent or curved. In such cases, the ejection axis 152 may be defined as the tangent to the path of ejection 148 at the end 122a of the hollow member 122.

[0106] Figure 13 depicts the upper part 128 of the housing 126. The upper part 128 is configured to at least partially cover and protect the upper surface of the electronic module 132. The upper part 128 is also arranged to support each of the hollow members 122 to hold them in place. For example, the upper part 128 comprises a connecting portion 156 for each of the hollow members 122. Each connecting portion 156 engages one end of a corresponding hollow member 122 and absorbs the one or more forces generated within the hollow member 122 when the masses are ejected. These forces are then isolated and directed away from the electronic module 132.

[0107] To further protect the electronic module 132, while reducing the weight and size of the housing 126, the upper part 128 comprises one or more reinforcing ribs 158. The ribs 158 form elongated ridges along the upper surface of the upper part 128, and each rib 158 is aligned parallel with a corresponding hollow member 122 connected to a connecting portion 156. In the example shown, there is one rib 158 associated with each hollow member 122, however in other examples there may be two or more ribs associated with each hollow member 122. The ribs 158 help strengthen the upper part 128 and stop the upper surface of the upper part 128 from deforming as the pyrotechnic devices are detonated.

[0108] The connecting portions 156 each delimit an aperture 160 through which an end of a hollow member 122 can be received. This allows the hollow members 122 to be securely affixed to the upper part 128. As mentioned, a pyrotechnic device (or other force generating device) may be received within the hollow member 122. The aperture 160 allows wires to be routed from the electronic module 132 to the pyrotechnic device, thereby allowing the length of the wires to be reduced.

[0109] The housing 126 comprises one or more attachment assemblies for attaching the housing 126 to the UAV 100. This allows the parachute deployment assembly to be removed from the UAV 100. This is useful because pyrotechnic devices can be dangerous, so they can be stored separately from the UAV 100 when the UAV is not in use.

[0110] Figure 14 depicts the lower part 130 of the housing 126. The lower part 130 is configured to at least partially cover and protect the lower surface of the electronic module 132. The lower part 130 extends below the electronic module 132, and is arranged between the electronic module 132 and the UAV.

[0111] The upper and lower parts 128, 130 can be brought together. In the example of Figure 14, the lower part 130 comprises four protrusions 176 each configured to abut an inner surface of the upper part 128. The protrusions may be wedge shaped to provide an abutting surface, while reducing the mass of the lower part 130.

[0112] The upper and lower parts 128, 130 can be connected via one or more attachment assemblies. Figures 13 and 14 depict each attachment assembly comprising a first through hole 162 formed in the upper part 128 and a second through hole 164 formed in the lower part 130. A fastener, such as a bolt or screw can extend through the first and second through holes 162, 164, thereby to connect the upper and lower parts 128, 130. The UAV may comprise an aperture/recess to receive the fastener, such that the housing 126 is also attached to the UAV. Thus, the same attachment assembly can be used to connect the upper and lower parts 128, 130 together, and to connect the housing 126 to the UAV. In other examples, separate attachment assemblies may connect the housing 126 to the UAV.

[0113] In a similar way, the electronic module 132 can be connected to the housing 126. Referring again to Figure 13, the upper part 128 comprises a third through hole 166. A fastener can be received in the third through hole 166 and extend into, or through, a fourth through hole formed in the electronic module 132. In this way, the electronic module 132 can be connected to, and be supported by, the housing 126. In some examples (not shown), the lower part 130 may comprise a fifth through hole into which the fastener can be received. This may provide a more secure arrangement for the electronic module 132. Figure 2 shows the electronic module 132 connected to the housing 126.

[0114] The attachment assemblies used to attach the electronic module 132 to the housing 126 may act as dampening mechanisms to isolate the electronic module 132 from vibrational forces generated during flight. This can avoid introducing noise into the sensor data measured by the sensors on the electronic module 132.

[0115] Figure 15 depicts a first example attachment assembly for dampening vibrations. In this example, the attachment assembly comprises a fastener 168 extending through the third through hole 166 formed in the upper part 128 and the fourth through hole 170 formed in the electronic module 132. To provide dampening, the attachment assembly further comprises a resilient member 172 connected to the fastener 168 and arranged between the upper part 128 and the electronic module 132. The fastener 168 connects the electronic module 132 to the housing 126 and the resilient member 172 allows the electronic module 132 to move relative to the housing 126 while absorbing any vibrational forces. Optionally, a second resilient member 174 may be arranged between the electronic module 132 and the lower part 130. In some examples, the fastener 168 extends into the lower part 130 and/or into the UAV 100.

[0116] A resilient member may be made from foam, sponge, rubber and such like. Alternatively, the resilient member may be a spring. The spring may extend around the fastener 168, for example.

[0117] In other examples, the fastener 168 may be omitted, and one or more resilient members may be arranged between the electronic module 132 and the housing 126, above and/or below the electronic module 132. The resilient members may be adhered to the housing and/or electronic module 132.

[0118] Figure 16 depicts a second example attachment assembly. In this example, the attachment assembly comprises at least one resilient member in the form of a spring 178 that is connected to the upper part 128. The electronic module 132 is suspended from the spring(s) 168. Alternatively, or additionally, the attachment assembly comprises at least one spring 180 connected to the lower part 130, and the electronic module 132 is mounted on the spring(s) 180. The resilient member(s) may therefore also act as an attachment assembly. To dampen vibrations, the spring(s) 168 may be used in conjunction with dampening materials (not shown in Figure 16), such as foam or rubber. For example, the dampening material may be arranged axially with the spring(s) 168, or the dampening material may be arranged elsewhere between the housing 126 and the electronic module 132.

[0119] Figures 15 and 16 also depict a force generating device 182 arranged at least partially within a hollow member 122. One or more wires 184 extend between the force generating device 182 and the electronic module 132. In this particular example, the force generating device 182 is a pyrotechnic device. The one or more wires 184 extend through the apertures 160 formed in the housing 126 and receive a signal or charge from the electronic module 132 when the controller determines that the parachute is to be deployed. The force generating device 182 generates a force to eject the mass 124 from the hollow member 122. The one or more wires 184 are arranged between a surface of the electronic module 132 and the housing 126. [0120] Figure 17 depicts a side view of the UAV 100 at the instance the parachute 134 has fully opened. The parachute 134 comprises a canopy 186, and a plurality of shroud lines 188 extending from the canopy 186 to a single suspension line 190. The suspension line 190 may be known as a riser. The suspension line 190 is connected to the main body of the UAV 100, and extends through a first aperture 192 formed in the upper part 128 of the housing 126, a second aperture 194 formed in the lower part 130 of the housing 126 and a third aperture 196 formed in the electronic module 132. The first aperture 192 is depicted most clearly in Figures 2 and 13. The second aperture 194 is depicted most clearly in Figures 3 and 14. The third aperture 196 is depicted most clearly in Figure 3. Figure 4 depicts the first, second and third 192, 194, 196 apertures arranged concentrically to allow the suspension line 190 to pass through the parachute deployment assembly and be connected to the UAV 100.

[0121] Figure 18 depicts the UAV 100 just after the time period shown in Figure 17. Due to the opening of the parachute, the suspension line 190 is under high tension as the UAV 100 is rapidly decelerated. These high forces can cause the housing 126 to break away from the main body 102 of the UAV 100. For example, the fasteners extending through the through holes 162, 164 can be pulled away from the UAV. This can cause the housing 126 and electronic module 132 to break loose. The fasteners which connect the housing 126 to the UAV 100 may be relatively fragile due to their small size, so are prone to breakage under high forces. Therefore, the housing 126 may be configured to break at the place where the fastener is connected to the housing 126. For example, the first and/or second through holes 162, 164 may break. For this reason, it is preferred that the suspension line 190 is connected directly to the UAV body 102 via more robust means. The first, second and third 192, 194, 196 apertures therefore allow the suspension line 190 to be routed through the housing 126 and electronic module 132 without requiring an off-center placement of the housing 126 and electronic module 132. An off-center arrangement can alter the center of mass of the UAV 100, which may impact the flight and aerodynamics of the UAV 100. The first, second and third 192, 194, 196 apertures also ensure that the housing and electronic module 132 remain connected/tethered to the UAV 100 should the fasteners break. Figure 18 shows the parachute deployment assembly moving along the suspension line 190 having just broken loose. This protects the electronic module 132 from damage, and stops any loose components from falling to the ground, which may cause injury or damage.

[0122] The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the disclosure, which is defined in the accompanying claims.