Abstract:
The invention provides a hovering aerial vehicle with removable rotor arms and protective shrouds. Removing the shrouds reduces the weight of the vehicle and increases flight time. Removing the rotor arms makes the vehicle easier to transport. Removable rotor arms also simplify field repair or replacement of damaged parts.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of U.S. Provisional Patent Application No. 61/127,638 filed May 15, 2008 which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF INVENTION 
     The present invention relates generally to hovering aerial vehicles. More particularly, the present invention relates to an aerial vehicle with removable rotor arms. 
     BACKGROUND OF THE INVENTION 
     Remote controlled drones with camera capability have been known for many years. These drones are used to provide visual reconnaissance for areas which are typically inaccessible by humans. These types of drones include a hovering aerial vehicle which is lifted and controlled by independently driven rotors or propellers. By varying the thrust generated by each of the rotors, the orientation and speed of the vehicle can be controlled. Various designs have been proposed for such an aerial vehicle, the primary requirement of which is to rigidly mount the rotors at fixed distances from the center of the craft, while minimizing the weight of the structure. 
     Use of a hovering aerial vehicle is especially effective for providing digital imagery or real-time digital video from aerial vantage points. For instance, first responders to a natural disaster or train derailment can benefit from this aerial vantage point to help determine the imminent danger of the situation. Alternatively, a hovering aerial vehicle can also be used as a security measure to provide a mobile, airborne security system. 
     In use, these aerial vehicles are typically controlled by a remote control, however, as will be understood, there may be hidden obstacles which can damage the vehicle while in flight. As it is quite expensive to replace one of these vehicles, it is necessary to provide protection to the vehicle. 
     It is, therefore, desirable to provide a hovering aerial vehicle with removable rotor arms. 
     SUMMARY OF THE INVENTION 
     The invention provides a hovering aerial vehicle with removable rotor arms. In another embodiment, the aerial vehicle has protective shrouds. The aerial vehicle includes a central pod from which a set of rotor arm assemblies extend. Each of the rotor arm assemblies includes a rotor which provides the necessary thrust to propel the vehicle in desired directions. Surrounding the rotor assemblies is at least one shroud which provides protection for when the vehicle collides with an obstacle. The protection may be provided by a single shroud surrounding each of the rotor arm assemblies or each rotor assembly may be associated with an individual protective shroud. 
     In a first aspect, the present invention provides a hovering aerial vehicle comprising a central pod; a set of rotor arm assemblies, each of the set of rotor arm assemblies connected to and extending from the central pod; and a set of shrouds for protecting the set of rotor arm assemblies. 
     Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein: 
         FIG. 1   a  is a top view of an embodiment of the hovering aerial vehicle; 
         FIG. 1   b  is a side view of the vehicle of  FIG. 1   a;    
         FIG. 2  is an oblique view of an individual rotor arm assembly of  FIG. 1   a  with a shroud segment attached; 
         FIGS. 3   a ,  3   b  and  3   c  are oblique, top and section views of the frame of the central pod of the hovering aerial vehicle of  FIG. 1   a;    
         FIG. 4  is an exploded view of the connection mechanism between the central pod frame and the rotor arm of  FIGS. 3   a - c;    
         FIG. 5  is an exploded view of a second embodiment of the hovering aerial vehicle; 
         FIG. 6   a  is a side view of a rotor arm assembly connected to the vehicle frame of  FIG. 5 ; 
         FIG. 6   b  is an enlarged view of the circle of  FIG. 6   a ; and 
         FIG. 7  is a perspective view of a hemispherical socket portion. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention provides a novel hovering aerial vehicle. Turning to  FIGS. 1   a  and  1   b , a top view and a side view of the aerial vehicle are shown, respectively. The aerial vehicle  10  includes a central pod  12  to which a set of rotor arm assemblies  14  are connected. Along with this physical connection, there is an electrical connection between each rotor arm assembly  14  and the central pod  12  to provide power, control and communications capabilities therebetween. Surrounding each of the set of rotor arm assemblies  14  is a protective shroud  16 . In the current embodiment, there is an individual shroud  16  for each of the rotor arm assemblies  14 . A schematic diagram of a rotor arm assembly  14  and protective shroud  16  is shown in  FIG. 2  which will be described in more detail below. The central pod  12  provides control, communications and data acquisition capabilities of the main processor  19  and mechanical support structure such as frame  18  for itself and the rotor arm assemblies  14 . The aerial vehicle  10  can also include a camera ( FIG. 5 , camera  86 ) for collecting digital imagery or video. The aerial vehicle  10  also comprises a landing gear apparatus  20 , including four legs  15 , as shown in  FIG. 1   b , which can be attached either to the central pod  12 , to at least one of the rotor arm assemblies  14  or to the central pod  12  and at least one of the rotor arm assemblies  14 . The landing gear apparatus  20  can also be designed to easily snap into place so that it is easily replaceable. The main processor  19  is located within the frame  18  and pod  12  for receiving instructions from a remote control (not shown) which is controlled by a user to determine the direction and height at which the aerial vehicle should travel. The processor  19  can be attached to the top, bottom or sides of the frame  18  but is preferably suspended near a center of the frame to minimize the effect of mechanical vibration on the processor during operation. 
     In one embodiment, as in  FIGS. 3 and 4 , the vehicle  10  includes a mechanism to enable each of the rotor arms  14  to be independently and easily detached from the frame  18  in the field. This allows, among other advantages, for convenient storage and transport of the vehicle  10 , rapid assembly of the aerial vehicle  10  in the field, or a convenient system for replacing worn or broken components. 
     Turning to  FIG. 2 , each rotor arm assembly  14  includes a rotor arm  22  which is connected at one end to a motor basket  24 . Within the motor basket  24  is a motor atop which a set of rotor blades  26  (forming part of a rotor  27 ) are mounted. As will be described below, the individual rotor arm assemblies  14  receive instructions from the main processor  19  to determine the rate of rotation for the set of rotor blades  26 . Near the other end of the rotor arm  22  is a retainer ring  28 , preferably threaded, for attachment with a corresponding threaded receptacle  38  ( FIG. 4 ) on frame  18  to secure the rotor arm assembly  14  by rotor arm  22  to frame  18  and to the central pod  12 . The ring  28  is tightened on to the receptacle  38 . 
     Surrounding the rotor arm assembly  14  is the shroud  16  which provides protection to the rotor arm assembly  14  during operation of the vehicle  10 . A support rod, or bar,  30  is connected between the motor basket  24  and the shroud  16  to provide further support to the overall vehicle  10 . Each shroud  16  includes an interconnect feature, seen as a male protrusion portion,  32  for attachment to, or mating with, a corresponding interconnect feature, seen as a female receiving portion,  39  (as seen in  FIG. 3   a  or  3   b ) on the frame  18 . A pair of additional shroud interconnect features  34  and  36  are also located on opposite ends of the shroud  16 , which is preferably circular, for connecting the shroud, or shroud segment, to an adjacent shroud (as schematically shown in  FIG. 2 ). In an alternative embodiment, individual circular rings can be used as the shrouds. These rings can be constructed of a strong, lightweight material like carbon fiber and can be fastened to the frame  18 , the arms  22  or to each other for support. In an alternative embodiment, a one-piece shroud is used to enclose all of the rotor arm assemblies  14  and therefore interconnect features  34  and  36  can be omitted. 
     An advantage of the present invention is that the protective shroud or shrouds  16  are attached to the rotor arm assemblies  14  to protect the individual rotor  27  and rotating blades  26  from contacting objects which can damage the vehicle. Furthermore, the shroud  16  can also shield the user, or operator from being struck by the rotating blades  26  during use. 
     Turning to  FIG. 3   a , a perspective view of the central pod is shown. The central pod  12  includes a set of threaded receptacles  38  located on the pod frame  18 . A truncated portion of the rotor arm  22  is shown in  FIGS. 3   a ,  3   b  and  3   c  and each is uniquely keyed as at  8  to incorporate a physical shape and features to complement the shape and features of the threaded receptacle  38  so that the arm  22  can only be inserted in a specific orientation. After the arm  22  is inserted into its associated receptacle  38 , the retainer ring  28  is then threaded onto the receptacle  38  to secure the rotor arm assembly  14  to the central pod frame  18 . This connection is further enhanced or supported by the connection between the interconnect features  32  ( FIG. 2) and 39  ( FIG. 3   a ). 
       FIG. 3   b  is a top view of the central pod while  FIG. 3   c  is a cross-sectional view taken along line  3   c - 3   c  of  FIG. 3   b.    
       FIG. 4  is an exploded view of the receptacle  38 , the truncated rotor arm  22  and the retaining ring  28 . The central pod  12  includes a central pod rotor arm interface circuit board  40  which includes a set of spring-loaded pins  42  which assist in providing a secure, reliable electrical connection to a rotor arm circuit board  44  (located at an end of the rotor arm  22 ) for passing power, control signals and information between the rotor arm assembly  14  and the central pod  12 . The spring-loaded pins  42  can also be used to communicate with sensors or other devices located on the rotor arms, such as, but not limited to range or proximity sensors or cameras, etc. (not shown) Alternatively, the information and control signals can be transmitted wirelessly. 
     In another embodiment, the rotor arm assemblies can be connected via a spring-loaded snap-in mechanism as shown in  FIGS. 5 to 7  (as will be described below). This allows the arms to be attached easily and allows the arms to snap off without breaking in the case of impact. 
     Turning to  FIGS. 5 to 7 , schematic diagrams of a second embodiment of an the hovering aerial vehicle is shown. The hovering aerial vehicle  50  includes many of the same parts as described with respect to the embodiment of  FIG. 1  but with different rotor arm assemblies. In this embodiment, the rotor arm assemblies are shown as snap-in assemblies. As shown in the exploded view of  FIG. 5 , the aerial vehicle  50  includes a central pod  52  which includes a set of sockets  54  for receiving individual rotor arms  56  belonging to rotor arm assemblies  58 . Each of the rotor arm assemblies includes a motor basket  57  and rotor blades  55 . A set of shrouds  60  to protect the rotor arm assemblies  58  are also shown. The vehicle  50  also includes a set of snap-in landing gear parts  62 . 
       FIG. 6   a  provides a cross-section of the rotor arm assembly  58  and corresponding socket  54  while  FIG. 6   b  provides an expanded view of the section  6   b  of  FIG. 6   a . The rotor arm assembly  58  includes motor arm plastics  64 , a motor  66 , a printed circuit board  68  and wires which connect the motor  66  to the circuit board  68 . The rotor arm  56  mates with the preferably hemispherical socket  54  in the vehicle  50  and preferably forms a joint which is hemispherical in shape as shown in  FIGS. 6   a  and  6   b . This shape allows the joint to separate in any direction away from the frame of the vehicle in the case of impact. 
     A printed circuit board  70  in the central pod  52  connects to circuitry inside the vehicle  50  and to the arm circuit board  68  using metal spring pin electrical contacts  72 . These electrical contacts can carry both power and data signals to the rotor arm assemblies  58 . In a preferred embodiment, an O-ring  74  is used between the rotor arm  56  and the socket  54  to provide an environmentally sealed connection and to reduce vibration of the arm  56  during use. 
     Retention of the arm  56  in the socket  54  is preferably achieved via spring loaded ball bearing plungers  76 . These are mounted on the centre plane of the hemisphere so that the arms  56  are easily removable. The ball bearing mates with corresponding holes in the arm  56  to assist in alignment and retention. When the arm is manufactured from plastic, these holes are preferably reinforced by metal to avoid wear. 
       FIG. 7  provides an isometric view of the arm socket  54  on the frame of the vehicle. The socket  54  includes a socket body  78 , a hemispherical socket  80 , the circuit board and spring pins  82  and spring loaded ball bearings  84 . 
     Control of the aerial vehicle  10  is preferably via a remote control, such as one of model airplanes. As will be understood, the remote control typically includes at least one joystick for controlling the direction of movement of the vehicle and a second control for controlling the height at which the vehicle hovers. These instructions are transmitted wirelessly between the remote control and the main processor  19  mounted to the central pod  12 . Once these instructions are received by the main processor, further instructions are then transmitted to the individual rotor arm assemblies  14  in  FIG. 1   a , and  58  in  FIG. 5 , via the central pod rotor arm interface circuit board  40  to rotate the rotor blades  26  in the desired direction in response to the remote control instructions. 
     The vehicle  10  is powered by a rechargeable battery  85  ( FIG. 5 ) which can be recharged in any number of ways. In one embodiment, the battery is mounted on the top of the frame  18 . It is located outside of the frame  18  so that it is accessible to the user to replace and recharge, when necessary. In the preferred embodiment, the center of mass of the battery  85  should be located directly above the geometric center of the frame  18  to balance the load on each of the rotor arm assemblies  14 . 
     In an alternative embodiment, the vehicle  10  includes a camera or other intelligence gathering payload  86 ,  FIG. 5 . 
     It will be understood that the systems and methods described herein may be embodied in a hardware implementation, mechanical enclosures or some combination thereof. It should also be understood that various modifications can be made to the example embodiments described and illustrated herein, without departing from the general scope of the inventions and associated claims.