Abstract:
Disclosed herein is a collapsible wing assembly of an unmanned aerial vehicle (UAV) and a method of locking and unlocking the collapsible wing assembly of an unmanned aerial vehicle (UAV). The collapsible wing assembly comprising a center wing adapted to be attached to the fuselage; and a pair of outboard wings, wherein each of the outboard edges of the center wing comprises a first attachment structure, and each of the inboard edges of the outboard wings comprises a second attachment structure, wherein the first attachment structure is operable to engage with the second attachment structure and displace the second attachment structure to a captive position towards the trailing edge of the center wing.

Description:
FIELD OF INVENTION 
     Embodiments of the present invention relate to a collapsible wing assembly of an unmanned aerial vehicle (UAV) 
     BACKGROUND 
     A main wing of an UAV may comprise a plurality of segments that can be assembled. As shown in  FIGS. 1   a  to  1   c , currently, the main wing of an UAV comprises a centre wing  101  attached to the fuselage of the aircraft, and a pair of outboard wings  103  that can be attached to the outboard edges  102  of the centre wing  101 . 
     Each outboard edge  102  of the centre wing  101  has a square shaped slot  105  and a circular slot  107  that are made of metal. An inboard edge  104  of each outboard wing  103  has a square shaped insert  109  and a circular guide  111  that are made of metal. In use, the slot  105  receives the insert  109  and the slot  107  receives the guide  111 . A spring lock  110  is provided on one face of the insert  109  to lock the insert  109  to a hole  113  provided on an underside of the of the centre wing  101 . 
     In order to assemble the main wing, the insert  109  and the guide  111  located on the inboard edge  104  of each outboard wing  103  are inserted into the respective slots  105 ,  107  located on the outboard edge  102  of the centre wing  101 . Once positive connection has been established, the spring lock  110  engages and locks onto the hole  113  found on the underside of the centre wing  101 . 
     In order to detach the outboard wings  103  on site, a special tool e.g. a pin is required so as to pierce through the hole  113  on the centre wing  101  and unlock the spring lock  110 . 
     Due to stringent tolerances between the insert  109  and the slot  105 , it is difficult to execute a smooth connecting action. 
     Furthermore, since a portion of the insert  109  is exposed, it is prone to damages which may further deteriorate the engaging or disengaging action of the wings  101 ,  103 . 
     Since the insert  109  and the slot  105  are the only point of engagement between the centre wing  101  and the outboard wing  101 , when the wings  101 ,  103  are subjected to high launching load, the trailing edge of joint between the centre wing  101  and the outboard wing  103  tends to twist outward in a span wise direction of the wings  101 ,  103 . 
     Furthermore, the dihedral angle of the outboard wing  103  depends on the molded dihedral angle of both the centre wing  101  and the outboard wing  103 . i.e. the angles at which the outboard edges  102  of the centre wing  101  and the inboard edges  104  of the outboard wing  103  are molded, determine the dihedral angle. Therefore, the centre wing  101  and outboard wing  103  are custom built for a particular dihedral angle. 
     There is thus a need to provide a collapsible wing that seeks to address one or more of the above disadvantages. 
     SUMMARY 
     According to a first aspect of the present invention, there is provided a collapsible wing assembly of an unmanned aerial vehicle (UAV) having a fuselage, the assembly comprising: a centre wing adapted to be attached to the fuselage; and a pair of outboard wings, wherein each of the outboard edges of the centre wing comprises a first attachment structure, and each of the inboard edges of the outboard wings comprises a second attachment structure, wherein the first attachment structure is operable to engage with the second attachment structure and displace the second attachment structure to a captive position towards the trailing edge of the centre wing. 
     The first attachment structure may comprise at least a pair of L-shaped profile locks, and the second attachment structure comprises at least a pair of locking pins, wherein each of the L-shaped profile lock is operable to engage with a respective locking pin and displace the locking pin to a captive position towards the trailing edge of the centre wing. 
     The centre wing may comprise a body and a centre wing adaptor mounted to an outboard edge of the body, and wherein the outboard wing comprises a body and an outboard wing adaptor mounted to an inboard edge of the body of the outboard wing, wherein the first attachment structure is provided on an end face of the centre wing adaptor, and the second attachment structure is provided on an end face of the outboard wing adaptor. 
     The airfoils of the centre wing adaptor and outboard wing adaptor matches respectively to the body of the centre wing and the outboard wing. 
     The centre wing adaptor and the outboard wing adaptor may be removably mounted respectively to the centre wing and the outboard wing. 
     One of the L-shaped profile lock maybe located proximate to the leading edge of the centre wing adaptor and the other may be located proximate to the trailing edge of the centre wing adaptor, wherein one of the locking pin may be located proximate to the leading edge of the outboard wing adaptor and the other may be located proximate to the trailing edge of the outboard wing adaptor, wherein each of the L-shaped profile lock may be operable to engage with a respective locking pin and displace the locking pin to a captive position towards the trailing edge of the centre wing. 
     Each of the L-shaped profile lock may comprises a hollow channel formed on an end face of the centre wing adaptor, wherein the hollow channel comprises a first arm pointing towards the bottom surface of the centre wing adaptor, and a second arm, inclined to the first arm, pointing towards the trailing edge of the centre wing. The first arm may be substantially perpendicular to the second arm. 
     The bottom surface of the centre wing adaptor may have a pair of openings corresponding to the respective openings of the first arm. 
     The top surface of the centre wing adapter may have a slot, positioned above the first arm of the L-shaped profile lock, for receiving a locking key to lock any relative movement of the centre wing and outboard wing in the captive position. 
     The dimension of a head of the locking pin matches with that of the opening of the first arm of the L-shaped profile lock, and the dimension of a stem of the locking pin matches with that of the hollow channel of the second arm of the L-shaped profile lock. 
     An opposing face of the centre wing adaptor and outboard wing adaptor may comprise one or more anchors for mounting the centre wing adaptor and outboard wing adaptor respectively to an outboard edge of the centre wing and an inboard edge of the outboard wing. 
     The locking key may comprise a head and a base, wherein the top surface of the head has an inclination to match the top surface of the centre wing adaptor, wherein the base has a slit and a resilient arm, the resilient arm comprises a stepped portion comprising a plurality of inclined steps terminating at the head. 
     In a locked position, the stepped portion may be operable to grip the stem of the an adjacent locking pin in order to lock any relative movement of the centre wing and the outer wing, and the base of the locking key locks with the opening found on the bottom surface of the centre wing adaptor. 
     The body of the locking key may comprise a slot for inserting a securing pin in order to secure the locking pin to the centre wing adaptor. 
     According to a second aspect of the present invention, there is provided a method of locking a collapsible wing assembly of an unmanned aerial vehicle (UAV) having a fuselage, the method comprising the steps of: providing a centre wing adapted to be attached to the fuselage; providing a pair of outboard wings; providing a first attachment structure to each outboard edges of the centre wing; providing a second attachment structure to each inboard edges of the outboard wings; engaging the first attachment structure with the second attachment structure; and displacing the second attachment structure to a captive position towards the trailing edge of the centre wing. 
     In the above method, the first attachment structure may comprise at least a pair of L-shaped profile locks, and the second attachment structure comprises at least a pair of locking pins, wherein each of the L-shaped profile lock is operable to engage with a respective locking pin and displace the locking pin to a captive position towards the trailing edge of the centre wing. 
     In the above method, the centre wing may comprise a body and a centre wing adaptor mounted to an outboard edge of the body, and wherein the outboard wing comprises a body and an outboard wing adaptor mounted to an inboard edge of the body of the outboard wing, wherein the first attachment structure is provided on an end face of the centre wing adaptor, and the second attachment structure is provided on an end face of the outboard wing adaptor. 
     The method may further comprise a step of inserting a locking key into a slot provided on the centre wing adaptor to lock the relative movement of the centre wing and the outboard wing. 
     According to a third aspect, there is provided a method of unlocking the above collapsible wing assembly locked by the above method, the method comprising the steps of: releasing the locking key; holding the centre wing and moving the outboard wing towards the leading edge of the centre wing; and moving the outboard wing downward to release the outboard wing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the enclosed drawings, in which: 
         FIGS. 1   a  to  1   c  are partial perspective views of a centre wing and outboard wing of a conventional UAV; 
         FIG. 2   a  is a partial perspective view of a centre wing and outboard wing (in an open position) of an UAV in accordance with an embodiment of the present invention; 
         FIG. 2   b  is a partial perspective view of a centre wing and outboard wing (in a locked position) of  FIG. 2   a;    
         FIG. 3   a  is a perspective view of a centre wing adaptor in accordance with an embodiment of the present invention; 
         FIG. 3   b  is an end view of the centre wing adaptor of  FIG. 3   a;    
         FIG. 3   c  is a sectional view of the centre wing adaptor of  FIG. 3   a;    
         FIG. 3   d  is a bottom view of the centre wing adaptor of  FIG. 3   a;    
         FIG. 4   a  is a perspective view of an outboard wing adaptor in accordance with an embodiment of the present invention; 
         FIG. 4   b  is an end view of the outboard wing adaptor of  FIG. 4   a;    
         FIG. 4   c  is a top view of outboard wing adaptor  FIG. 4   a;    
         FIG. 4   d  is a side view of the outboard wing adaptor of  FIG. 4   a;    
         FIGS. 5   a  to  5   d  are exemplary views to illustrate a method of locking the centre wing adaptor with the outboard wing adaptor; 
         FIG. 6   a  is a perspective view of a locking key in accordance with an example embodiment; 
         FIG. 6   b  is a bottom view of the locking key of  FIG. 6   a;    
         FIG. 6   c  is a front view of the locking key  FIG. 6   a ; and 
         FIGS. 7   a  and  7   b  are exemplary views to illustrate a locking key in an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention eliminate the need for any special tool for detaching outboard wings and centre wing of an UAV, which is advantageous for operational deployment. 
     Embodiments of the present invention provide a smooth and positive engagement of the outboard wings and centre wing of an UAV by employing a “profile lock” concept. 
     Embodiments of the present invention provide centre wing and outboard wings that are operable to be attached and locked with each other. 
     By employing a dual locking system, embodiments of the present invention provide a seamless joint between the outboard wings and centre wing of an UAV even when the wings are subjected to a high launching load. 
     In embodiments of the invention, substantial portion of the profile lock are embedded inside the outboard wings and centre wing. The embedded feature of the profile lock increases the lifespan of the UAV. 
     Embodiments of the present invention provide flexibility to alter the wing dihedral angle of an UAV by swapping an adaptor attached to the centre wing and/or outboard wings. 
       FIG. 2   a  is a partial perspective view of a centre wing  201  and outboard wing  203  (in an open position) of an UAV in accordance with an embodiment of the present invention. 
     Each of the outboard edge of the centre wing  201  and the inboard edge of the outboard wing  203  has an attachment structure for attaching the outboard wing  203  to the centre wing  201 . 
     The centre wing  201  has a body  202  and a centre wing adaptor  220  attached to an outboard edge of the body  202 . The centre wing adaptor  220  forms the outboard edge of the centre wing  201 . The airfoil of the centre wing adaptor  220  matches with that of the body  202  of the centre wing  201 . 
     The attachment structure of the centre wing  201  consists of two L-shaped profile locks  205 ,  207 . The first L-shaped profile lock  205  is located on the centre wing adaptor  220 , proximate to the leading edge of the centre wing adaptor  220 . The second L-shaped profile lock  207 , substantially identical to the profile lock  205 , is located proximate to a trailing edge of the centre wing adaptor  220 . 
     The outboard wing  203  has a body  204  and an outboard wing adaptor  240  attached to an inboard edge of the body  204 . The outboard wing adaptor  240  form the inboard edge of the outboard wing  203 . The airfoil of the outboard wing adaptor  240  matches with that of the body  204  of the outboard wing  203 . 
     The attachment structure of the outboard wing  203  consists of two locking pins  209 ,  211 . The first locking pin  209  is located proximate to the leading edge of the outboard wing adaptor  240 . The second locking pin  211 , substantially identical to the locking pin  209 , is located proximate to the trailing edge of the outboard wing adaptor  240 . The locking pins  209 ,  211  comprise a circular head  210  and a stem  212 . The dimensions of the head  210  and stem  212  are designed to match the openings of the L-shaped profile locks  205 ,  207  in order to engage and lock a locking pin  209 ,  211  with a respective L-shaped profile lock  205 ,  207 . 
     The adaptors  220 ,  240  can be fabricated for example with a tough and scratch-resistant material such as ABS plastic, delrin, aluminium or steel by e.g. an injection moulding or diecast process. 
     Each of the L-shaped profile lock  205 ,  207  is operable to engage with a respective locking pin  209 ,  211  and displace the locking pin  209 ,  211  to a captive position towards the trailing edge of the centre wing  201  (Refer to  FIGS. 5   a  and  5   d ). 
     A substantially flat locking key  213  is shown inserted into a slot  307  (refer  FIG. 3   a ) on a top surface of the centre wing adaptor  220  in order to provide an additional rigid and positive lock that can avoid any relative movement between the centre wing  201  and the outboard wing  203 . When inserted, the base of the locking key  213  is hidden within the opening  301  (refer  FIG. 3   a ) located on the underside of the centre wing adaptor  240 . The base of the locking key  213  is designed to allow a user to push up the locking key  213  via the opening  301  while unlocking. 
       FIG. 2   b  is a partial perspective view of a centre wing  201  and outboard wing  203  (in a closed position) of an UAV in accordance with an embodiment of the present invention. It can be appreciated, in a locked position, there is substantially minimum gap between the centre wing adaptor  220  and the outboard wing adaptor, whereby a smooth joint between the centre wing  201  and outboard wing  203  is achieved. 
       FIG. 3   a  is a perspective view of a centre wing adaptor  220  in accordance with an embodiment of the present invention. The centre wing adaptor  220  has an airfoil-shaped body with a substantially flat end face  305 . 
     The end face  305  of the centre wing adaptor  220  has a locking structure consisting two L-shaped profile locks  205 ,  207 . The first L-shaped profile lock  205  located near the leading edge  309  of the centre wing adaptor  220 . The second L-shaped profile lock  207 , identical to the profile lock  205 , is located near the trailing edge  311  of the centre wing adaptor  220 . 
     Each of the L-shaped profile locks  205 ,  207  comprise a hollow channel. The hollow channel is formed by lacking a material during a moulding process and the dimensions are appropriate to receive a locking pin  209 ,  211 . 
     A first arm  302  of each L-shaped profile lock  205 ,  207  has an opening  301  that points towards the bottom surface of the centre wing adaptor  220 , while a second arm  303 , substantially perpendicular or inclined to the first arm  302 , points towards the trailing edge of the centre wing  201  and terminates into a captive position in the body of the centre wing adaptor  220 . 
     The opposing face of the centre wing adaptor  220  has a pair of anchors  320 ,  330  for mounting the centre wing adaptor  220  to an outboard edge of the centre wing  201 . Attached to the anchor  320 , is a launching pin  310 , which extends below the bottom surface of the centre wing adaptor  220 . The launching pin  310  is used for launching the UAV. 
     The bottom surface of the centre wing adaptor  220  has a pair of openings  301  corresponding to a respective opening  301  of the first arm  302 . 
     The top surface of the centre wing adaptor  220  has a slot  307  positioned above the first arm  302  of the L-shaped profile lock  205 . The slot  307  is designed to accommodate a substantially flat locking key  213  (refer  FIG. 2 ,  FIGS. 6   a - 6   c ) in order to provide an additional locking to any relative movement between the centre wing  201  and the outboard wings  203 . 
       FIG. 3   b  is an end view of the centre wing adaptor  220  of  FIG. 3   a  in a direction of  340  showing the relative positioning of the profile locks  205 ,  207  and the launching pin  310 . 
       FIG. 3   c  is a sectional view of the centre wing adaptor  220  of  FIG. 3   a  in a direction of  350  showing the slot  307  for accommodating the locking key  213  and inner dimensions of the arms  302 ,  303  of the L-shaped profile lock  205 ,  207 . 
       FIG. 3   d  is a bottom view of the centre wing adaptor of  FIG. 3   a  clearly showing the openings  301  of the L-shaped profile locks  205 ,  207 . 
       FIG. 4   a  is a perspective view of an outboard wing adaptor  240  in accordance with an embodiment of the present invention. 
     The outboard wing adaptor  240  also has an airfoil-shaped body with a substantially flat end face  405 . A locking pin  209  is located proximate to the leading edge of the outboard wing adaptor  240 . Another locking pin  211 , identical to the locking pin  209 , is located proximate to the trailing edge of the outboard wing adaptor  240 . The locking pins  209 ,  211  comprise a circular head  210  and a stem  212 . 
     Each of the L-shaped profile lock  205 ,  207  is operable to engage with a respective locking pin  209 ,  211  and displace the locking pin  209 ,  211  to a captive position towards the trailing edge of the centre wing  201 . 
     The dimension of the heads  210  matches with that of the openings  301  of the L-shaped profile locks  205 ,  207 . Furthermore, the dimension of the stem  212  matches with that of the openings  303  of the L-shaped profile locks  205 ,  207 . The terminal portion of the arm  303  of the profile locks  205 ,  207  is towards the trailing edge of the wings  201 ,  203 , such that the L-shaped profile lock  205 ,  207  engages with a respective locking pin  209 ,  211  and displaces the locking pin  209 ,  211  to a captive position towards the trailing edge of the centre wing  201 . 
     An opposing face of the outboard wing adaptor  240  has an anchor  450  for mounting the outboard wing adaptor  240  to an inboard edge of the outboard wing  203 . The bottom surface  401  (refer  FIG. 4   b ) of the outboard wing adaptor  240  is substantially flat. 
       FIG. 4   b  is an end view of the outboard wing adaptor  240  of  FIG. 4   a  in a direction of  410  showing the relative positioning of the locking pins  209 ,  211  on the end face  405 . 
       FIG. 4   c  is a bottom view of the outboard wing adaptor  240  of  FIG. 4   a  in a direction of  420  showing the relative positioning of the locking pins  209 ,  211  and the anchor  450 . 
       FIG. 4   d  is a side view of the outboard wing adaptor  240  of  FIG. 4   a  showing the locking pins  209 ,  211  and the anchor  450 . 
       FIGS. 5   a  to  5   d  are exemplary views to illustrate a method of locking the centre wing adaptor  220  with the outboard wing adaptor  240 . 
     As shown in  FIGS. 5   a  and  5   b , the outboard wing  203  and centre wing  201  are brought closer such that the locking pins  209 ,  209  of the outboard wing adaptor  240  are aligned directly below the openings  301  on the underside of the centre wing adaptor  220 . 
     Subsequently, as shown in  FIG. 5   c , the locking pins  209 ,  211  are inserted into a respective opening  301  of the centre wing adaptor  220  and the outboard wing  203  is moved upward into the centre wing  201  such that the locking pins  209 ,  211  reach the upward limit of the arm  302  of the L-shaped profile locks  205 ,  207 . 
     After this, as shown in  FIG. 5   d , the centre wing  201  is firmly held by a user and the outboard wing  203  is moved rearward into the centre wing  201  until the lateral limit of the L-shaped profile locks  205 ,  207  is reached. i.e. at the captive position. 
     Thereafter, a locking key  213  is inserted into the slot  307  located on the top surface of the centre wing adaptor  220 . The locking key  213  is pushed downwards until the base of the locking key locks into the opening  301 . After locking, the locking key  213  cannot be unlocked by any vibrations or when the UAV is in operation. 
     In order to unlock, an operator of the UAV can push up the locking key  213  by applying a force using his/fingers into the opening  301  on the underside of the centre wing adaptor  220  whereby the head of the locking key  511  (refer  FIG. 6   a ) pops out of the slot  307 . The locking key  213  is then removed out of the slot  307 . 
     In order to unlock the outboard wing  203  and the centre wing  201 , the operations shown in  FIGS. 5   a - 5   d  are reversed. i.e. the centre wing  201  is firmly held by a user and the outboard wing  203  is moved forward followed by a clockwise twisting action to dislodge the outboard wing  203  from the centre wing  201 . 
       FIG. 6   a  is a perspective view of a locking key  213  in accordance with an example embodiment. 
     The locking key  214  comprises a substantially flat body  502  having a substantially flat head  511  and a base  503 . The top surface of the head  511  has an inclination to match the outer surface of the centre wing adaptor  220 . Furthermore, the head also has arcuate ends  509 ,  519  that match with the corresponding arcuate portion of the slot  307 . The base  503  has a slit  505  and a resilient arm  501 . The resilient arm  501  has a stepped portion  507  which terminates at the head  511 . The locking key  213  is designed to be received into the slot  307  on the centre wing adaptor  220 . 
     While insertion, the stepped portion  507  faces the trailing edge  311  of the centre wing adaptor  220 . After insertion, the locking key  213  is pushed downward until the base  503  and the arm  501  locks with the opening  301  on the underside of the centre wing adaptor  220  such that the head  511  is flush with the surface of the centre wing adaptor  220 . The stepped portion  507  grips with the stem  212  of the locking pin  209  in order to lock the relative movement of the centre wing adaptor  220  and the outer wing adaptor  240 . 
       FIG. 6   b  is a bottom view of the locking key  213  of  FIG. 6   a  showing the two arcuate ends  509 ,  519  of the head  511 , the base  503 , the slit  505 , the resilient arm  501  and the stepped portion  507 . 
       FIG. 6   c  is a front view the locking key  213  of  FIG. 6   a  showing the inclination of the top surface  511  and its arcuate ends  509 ,  511 , the stepped portion  507 , the resilient arm  501 , the slit  505  and the base  503 . 
       FIGS. 7   a  and  7   b  are exemplary views to illustrate a locking key  700  in an alternative embodiment whereby the locking key  700  is prevented from being detached away from the centre wing adaptor  220 . In order to exemplify, a stem  212  of the locking pin  209  is positioned into the end of the profile lock  205 . 
       FIG. 7   a  shows the locking key  700  in an open position. The body of the locking key  700  has an oval shaped slot  702  cut along a height of a base  703  of the locking key  700 . A securing pin  705  is inserted into the slot  703  in order to secure the locking pin to the centre wing adaptor  220 . As in the previous embodiment the resilient arm  701  has a stepped portion  707 . 
       FIG. 7   b  shows the locking key  700  in a closed position. Once the centre wing adaptor  220  is locked with the outboard wing adaptor  240 , the secured locking key  700  can be easily inserted into the slot  307  of the centre wing adaptor  220 . The locking pin  700  is then pushed downward  703  until the base  703  and the arm  701  locks with the opening  301  on the underside of the centre wing adaptor  220  such that the head of the locking pin  700  is flush with the surface of the centre wing adaptor  220 . The stepped portion  707  grips with the stem  212  of the locking pin  209  in order to lock the relative movement of the centre wing adaptor  220  and the outer wing adaptor  240 . In order to unlock, a user pushes up the base  703  using a finger via the opening  301  until the head of the locking key  700  pops out for removing the locking key  700 . 
     It will be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive. 
     For instance, the number of locking pins  209 ,  211  and the L-shaped profile locks  205 ,  207  can be more than two. The outboard wing adaptor  240  can be integral with the outboard wing  203 . The centre wing adaptor  220  can be integral with the centre wing  201 . The locking pins  209 ,  211  can be provided on the centre wing  201  and the L-shaped profile locks  205 ,  207  can be provided on the outboard wing with changes to the direction of locking. 
     Embodiments of the present invention can provide flexibility to alter the wing dihedral angle by merely swapping the centre wing adaptor  220  and/or the outboard wing adaptor  240 .